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    Alterations in tissue ferritins in iron storage disorders. Powell L W,McKeering L V,Halliday J W Gut Purified tissue ferritins isolated from Bantu subjects with gross haemosiderosis, from a patient with idiopathic haemochromatosis (HC) treated by phlebotomy, and from rats with experimental iron overload were studied in order to determine the significance of the abnormality previously demonstrated in tissue isoferritins in patients with IHC. The isoferrin profile of the tissues from the Bantu subjects and the iron-loaded rats showed a similar abnormality to that previously found in patients with untreated IHC--that is, an abnormally uniform distribution of iron-containing isoferritins with an increase in the more basic isoferritins and an apparent absence of the more acidic ones. In contrast, tissues from the patient with treated IHC, who was iron depleted at the time of death, showed the normal organ-specific isoferritin distribution. These findings strongly suggest that the abnormal distribution of tissue isoferritins in IHC is an acquired phenomenon and unlikely to be related to an underlying genetic defect in ferritin or iron metabolism. 10.1136/gut.16.11.909
    Plasticity of ether lipids promotes ferroptosis susceptibility and evasion. Zou Yilong,Henry Whitney S,Ricq Emily L,Graham Emily T,Phadnis Vaishnavi V,Maretich Pema,Paradkar Sateja,Boehnke Natalie,Deik Amy A,Reinhardt Ferenc,Eaton John K,Ferguson Bryan,Wang Wenyu,Fairman Joshua,Keys Heather R,Dančík Vlado,Clish Clary B,Clemons Paul A,Hammond Paula T,Boyer Laurie A,Weinberg Robert A,Schreiber Stuart L Nature Ferroptosis-an iron-dependent, non-apoptotic cell death process-is involved in various degenerative diseases and represents a targetable susceptibility in certain cancers. The ferroptosis-susceptible cell state can either pre-exist in cells that arise from certain lineages or be acquired during cell-state transitions. However, precisely how susceptibility to ferroptosis is dynamically regulated remains poorly understood. Here we use genome-wide CRISPR-Cas9 suppressor screens to identify the oxidative organelles peroxisomes as critical contributors to ferroptosis sensitivity in human renal and ovarian carcinoma cells. Using lipidomic profiling we show that peroxisomes contribute to ferroptosis by synthesizing polyunsaturated ether phospholipids (PUFA-ePLs), which act as substrates for lipid peroxidation that, in turn, results in the induction of ferroptosis. Carcinoma cells that are initially sensitive to ferroptosis can switch to a ferroptosis-resistant state in vivo in mice, which is associated with extensive downregulation of PUFA-ePLs. We further find that the pro-ferroptotic role of PUFA-ePLs can be extended beyond neoplastic cells to other cell types, including neurons and cardiomyocytes. Together, our work reveals roles for the peroxisome-ether-phospholipid axis in driving susceptibility to and evasion from ferroptosis, highlights PUFA-ePL as a distinct functional lipid class that is dynamically regulated during cell-state transitions, and suggests multiple regulatory nodes for therapeutic interventions in diseases that involve ferroptosis. 10.1038/s41586-020-2732-8
    Intercellular interaction dictates cancer cell ferroptosis via NF2-YAP signalling. Nature Ferroptosis, a cell death process driven by cellular metabolism and iron-dependent lipid peroxidation, has been implicated in diseases such as ischaemic organ damage and cancer. The enzyme glutathione peroxidase 4 (GPX4) is a central regulator of ferroptosis, and protects cells by neutralizing lipid peroxides, which are by-products of cellular metabolism. The direct inhibition of GPX4, or indirect inhibition by depletion of its substrate glutathione or the building blocks of glutathione (such as cysteine), can trigger ferroptosis. Ferroptosis contributes to the antitumour function of several tumour suppressors such as p53, BAP1 and fumarase. Counterintuitively, mesenchymal cancer cells-which are prone to metastasis, and often resistant to various treatments-are highly susceptible to ferroptosis. Here we show that ferroptosis can be regulated non-cell-autonomously by cadherin-mediated intercellular interactions. In epithelial cells, such interactions mediated by E-cadherin suppress ferroptosis by activating the intracellular NF2 (also known as merlin) and Hippo signalling pathway. Antagonizing this signalling axis allows the proto-oncogenic transcriptional co-activator YAP to promote ferroptosis by upregulating several ferroptosis modulators, including ACSL4 and TFRC. This finding provides mechanistic insights into the observations that cancer cells with mesenchymal or metastatic property are highly sensitive to ferroptosis. Notably, a similar mechanism also modulates ferroptosis in some non-epithelial cells. Finally, genetic inactivation of the tumour suppressor NF2, a frequent tumorigenic event in mesothelioma, rendered cancer cells more sensitive to ferroptosis in an orthotopic mouse model of malignant mesothelioma. Our results demonstrate the role of intercellular interactions and intracellular NF2-YAP signalling in dictating ferroptotic death, and also suggest that malignant mutations in NF2-YAP signalling could predict the responsiveness of cancer cells to future ferroptosis-inducing therapies. 10.1038/s41586-019-1426-6
    Nedd4 ubiquitylates VDAC2/3 to suppress erastin-induced ferroptosis in melanoma. Yang Yongfei,Luo Meiying,Zhang Kexin,Zhang Jun,Gao Tongtong,Connell Douglas O',Yao Fengping,Mu Changwen,Cai Bingyu,Shang Yuxue,Chen Wei Nature communications Ferroptosis is a newly defined form of regulated cell death characterized by the iron-dependent accumulation of lipid hydroperoxides. Erastin, the ferroptosis activator, binds to voltage-dependent anion channels VDAC2 and VDCA3, but treatment with erastin can result in the degradation of the channels. Here, the authors show that Nedd4 is induced following erastin treatment, which leads to the ubiquitination and subsequent degradation of the channels. Depletion of Nedd4 limits the protein degradation of VDAC2/3, which increases the sensitivity of cancer cells to erastin. By understanding the molecular mechanism of erastin-induced cellular resistance, we can discover how cells adapt to new molecules to maintain homeostasis. Furthermore, erastin-induced resistance mediated by FOXM1-Nedd4-VDAC2/3 negative feedback loop provides an initial framework for creating avenues to overcome the drug resistance of ferroptosis activators. 10.1038/s41467-020-14324-x
    DJ-1 suppresses ferroptosis through preserving the activity of S-adenosyl homocysteine hydrolase. Cao Ji,Chen Xiaobing,Jiang Li,Lu Bin,Yuan Meng,Zhu Difeng,Zhu Hong,He Qiaojun,Yang Bo,Ying Meidan Nature communications Ferroptosis is a newly characterized form of regulated cell death mediated by iron-dependent accumulation of lipid reactive oxygen species and holds great potential for cancer therapy. However, the molecular mechanisms underlying ferroptosis remain largely elusive. In this study, we define an integrative role of DJ-1 in ferroptosis. Inhibition of DJ-1 potently enhances the sensitivity of tumor cells to ferroptosis inducers both in vitro and in vivo. Metabolic analysis and metabolite rescue assay reveal that DJ-1 depletion inhibits the transsulfuration pathway by disrupting the formation of the S-adenosyl homocysteine hydrolase tetramer and impairing its activity. Consequently, more ferroptosis is induced when homocysteine generation is decreased, which might be the only source of glutathione biosynthesis when cystine uptake is blocked. Thus, our findings show that DJ-1 determines the response of cancer cells to ferroptosis, and highlight a candidate therapeutic target to potentially improve the effect of ferroptosis-based antitumor therapy. 10.1038/s41467-020-15109-y
    RBMS1 regulates lung cancer ferroptosis through translational control of SLC7A11. Zhang Wenjing,Sun Yu,Bai Lu,Zhi Lili,Yang Yun,Zhao Qingzhi,Chen Chaoqun,Qi Yangfan,Gao Wenting,He Wenxia,Wang Luning,Chen Dan,Fan Shujun,Chen Huan,Piao Hai-Long,Qiao Qinglong,Xu Zhaochao,Zhang Jinrui,Zhao Jinyao,Zhang Sirui,Yin Yue,Peng Chao,Li Xiaoling,Liu Quentin,Liu Han,Wang Yang The Journal of clinical investigation Ferroptosis, an iron-dependent nonapoptotic cell death, is a highly regulated tumor suppressing process. However, functions and mechanisms of RNA-binding proteins in regulation of evasion of ferroptosis during lung cancer progression are still largely unknown. Here, we report that the RNA-binding protein RBMS1 participates in lung cancer development via mediating ferroptosis evasion. Through an shRNA-mediated systematic screen, we discovered that RBMS1 is a key ferroptosis regulator. Clinically, RBMS1 was elevated in lung cancer and its high expression was associated with reduced patient survival. Conversely, depletion of RBMS1 inhibited lung cancer progression both in vivo and in vitro. Mechanistically, RBMS1 interacted with the translation initiation factor eIF3d directly to bridge the 3'- and 5'-UTR of SLC7A11. RBMS1 ablation inhibited the translation of SLC7A11, reduced SLC7A11-mediated cystine uptake, and promoted ferroptosis. In a drug screen that targeted RBMS1, we further uncovered that nortriptyline hydrochloride decreased the level of RBMS1, thereby promoting ferroptosis. Importantly, RBMS1 depletion or inhibition by nortriptyline hydrochloride sensitized radioresistant lung cancer cells to radiotherapy. Our findings established RBMS1 as a translational regulator of ferroptosis and a prognostic factor with therapeutic potential and clinical value. 10.1172/JCI152067
    Prokineticin-2 prevents neuronal cell deaths in a model of traumatic brain injury. Bao Zhongyuan,Liu Yinlong,Chen Binglin,Miao Zong,Tu Yiming,Li Chong,Chao Honglu,Ye Yangfan,Xu Xiupeng,Sun Guangchi,Zhao Pengzhan,Liu Ning,Liu Yan,Wang Xiaoming,Lam Sin Man,Kagan Valerian E,Bayır Hülya,Ji Jing Nature communications Prokineticin-2 (Prok2) is an important secreted protein likely involved in the pathogenesis of several acute and chronic neurological diseases through currently unidentified regulatory mechanisms. The initial mechanical injury of neurons by traumatic brain injury triggers multiple secondary responses including various cell death programs. One of these is ferroptosis, which is associated with dysregulation of iron and thiols and culminates in fatal lipid peroxidation. Here, we explore the regulatory role of Prok2 in neuronal ferroptosis in vitro and in vivo. We show that Prok2 prevents neuronal cell death by suppressing the biosynthesis of lipid peroxidation substrates, arachidonic acid-phospholipids, via accelerated F-box only protein 10 (Fbxo10)-driven ubiquitination, degradation of long-chain-fatty-acid-CoA ligase 4 (Acsl4), and inhibition of lipid peroxidation. Mice injected with adeno-associated virus-Prok2 before controlled cortical impact injury show reduced neuronal degeneration and improved motor and cognitive functions, which could be inhibited by Fbxo10 knockdown. Our study shows that Prok2 mediates neuronal cell deaths in traumatic brain injury via ferroptosis. 10.1038/s41467-021-24469-y
    Membrane Damage during Ferroptosis Is Caused by Oxidation of Phospholipids Catalyzed by the Oxidoreductases POR and CYB5R1. Yan Bo,Ai Youwei,Sun Qi,Ma Yan,Cao Yang,Wang Jiawen,Zhang Zhiyuan,Wang Xiaodong Molecular cell Ferroptosis is a form of necrotic cell death caused by iron-dependent peroxidation of polyunsaturated phospholipids on cell membranes and is actively suppressed by the cellular antioxidant systems. We report here that oxidoreductases, including NADPH-cytochrome P450 reductase (POR) and NADH-cytochrome b5 reductase (CYB5R1), transfer electrons from NAD(P)H to oxygen to generate hydrogen peroxide, which subsequently reacts with iron to generate reactive hydroxyl radicals for the peroxidation of the polyunsaturated fatty acid (PUFA) chains of membrane phospholipids, thereby disrupting membrane integrity during ferroptosis. Genetic knockout of POR and CYB5R1 decreases cellular hydrogen peroxide generation, preventing lipid peroxidation and ferroptosis. Moreover, POR knockdown in mouse liver prevents ConA-induced liver damage. Ferroptosis, therefore, is a result of incidental electron transfer carried out by POR/CYB5R1 oxidoreductase and thus needs to be constitutively countered by the antioxidant systems. 10.1016/j.molcel.2020.11.024
    Selenium-GPX4 axis protects follicular helper T cells from ferroptosis. Yao Yin,Chen Zhian,Zhang Hao,Chen Cailing,Zeng Ming,Yunis Joseph,Wei Yunbo,Wan Yanmin,Wang Naiqi,Zhou Mingzhe,Qiu Chao,Zeng Qunxiong,Ong Hong Sheng,Wang Hao,Makota Fadzai Victor,Yang Yang,Yang Zhaohui,Wang Nan,Deng Jun,Shen Chao,Xia Yan,Yuan Lin,Lian Zhaoqin,Deng Yike,Guo Cuilian,Huang Ao,Zhou Pengcheng,Shi Haibo,Zhang Weitian,Yi Hongliang,Li Dongmei,Xia Ming,Fu Jing,Wu Ning,de Haan Judy B,Shen Nan,Zhang Wenhong,Liu Zheng,Yu Di Nature immunology Follicular helper T (T) cells are a specialized subset of CD4 T cells that essentially support germinal center responses where high-affinity and long-lived humoral immunity is generated. The regulation of T cell survival remains unclear. Here we report that T cells show intensified lipid peroxidation and altered mitochondrial morphology, resembling the features of ferroptosis, a form of programmed cell death that is driven by iron-dependent accumulation of lipid peroxidation. Glutathione peroxidase 4 (GPX4) is the major lipid peroxidation scavenger and is necessary for T cell survival. The deletion of GPX4 in T cells selectively abrogated T cells and germinal center responses in immunized mice. Selenium supplementation enhanced GPX4 expression in T cells, increased T cell numbers and promoted antibody responses in immunized mice and young adults after influenza vaccination. Our findings reveal the central role of the selenium-GPX4-ferroptosis axis in regulating T homeostasis, which can be targeted to enhance T cell function in infection and following vaccination. 10.1038/s41590-021-00996-0
    Non-canonical Glutamate-Cysteine Ligase Activity Protects against Ferroptosis. Cell metabolism Cysteine is required for maintaining cellular redox homeostasis in both normal and transformed cells. Deprivation of cysteine induces the iron-dependent form of cell death known as ferroptosis; however, the metabolic consequences of cysteine starvation beyond impairment of glutathione synthesis are poorly characterized. Here, we find that cystine starvation of non-small-cell lung cancer cell lines induces an unexpected accumulation of γ-glutamyl-peptides, which are produced due to a non-canonical activity of glutamate-cysteine ligase catalytic subunit (GCLC). This activity is enriched in cell lines with high levels of NRF2, a key transcriptional regulator of GCLC, but is also inducible in healthy murine tissues following cysteine limitation. γ-glutamyl-peptide synthesis limits the accumulation of glutamate, thereby protecting against ferroptosis. These results indicate that GCLC has a glutathione-independent, non-canonical role in the protection against ferroptosis by maintaining glutamate homeostasis under cystine starvation. 10.1016/j.cmet.2020.12.007
    Emerging Roles of Energy Metabolism in Ferroptosis Regulation of Tumor Cells. Yao Xuemei,Li Wei,Fang De,Xiao Chuyu,Wu Xiao,Li Menghuan,Luo Zhong Advanced science (Weinheim, Baden-Wurttemberg, Germany) Ferroptosis is a new form of regulated cell death, which is characterized by the iron-dependent accumulation of lethal lipid peroxides and involved in many critical diseases. Recent reports revealed that cellular energy metabolism activities such as glycolysis, pentose phosphate pathway (PPP), and tricarboxylic acid cycle are involved in the regulation of key ferroptosis markers such as reduced nicotinamide adenine dinucleotide phosphate (NADPH), glutathione (GSH), and reactive oxygen species (ROS), therefore imposing potential regulatory roles in ferroptosis. Remarkably, tumor cells can activate adaptive metabolic responses to inhibit ferroptosis for self-preservation such as the upregulation of glycolysis and PPP. Due to the rapid proliferation of tumor cells and the intensified metabolic rate, tumor energy metabolism has become a target for disrupting the redox homeostasis and induce ferroptosis. Based on these emerging insights, regulatory impact of those-tumor specific metabolic aberrations is systematically characterized, such as rewired glucose metabolism and metabolic compensation through glutamine utilization on ferroptosis and analyzed the underlying molecular mechanisms. Additionally, those ferroptosis-based therapeutic strategies are also discussed by exploiting those metabolic vulnerabilities, which may open up new avenues for tumor treatment in a clinical context. 10.1002/advs.202100997
    Ferroptosis as a p53-mediated activity during tumour suppression. Jiang Le,Kon Ning,Li Tongyuan,Wang Shang-Jui,Su Tao,Hibshoosh Hanina,Baer Richard,Gu Wei Nature Although p53-mediated cell-cycle arrest, senescence and apoptosis serve as critical barriers to cancer development, emerging evidence suggests that the metabolic activities of p53 are also important. Here we show that p53 inhibits cystine uptake and sensitizes cells to ferroptosis, a non-apoptotic form of cell death, by repressing expression of SLC7A11, a key component of the cystine/glutamate antiporter. Notably, p53(3KR), an acetylation-defective mutant that fails to induce cell-cycle arrest, senescence and apoptosis, fully retains the ability to regulate SLC7A11 expression and induce ferroptosis upon reactive oxygen species (ROS)-induced stress. Analysis of mutant mice shows that these non-canonical p53 activities contribute to embryonic development and the lethality associated with loss of Mdm2. Moreover, SLC7A11 is highly expressed in human tumours, and its overexpression inhibits ROS-induced ferroptosis and abrogates p53(3KR)-mediated tumour growth suppression in xenograft models. Our findings uncover a new mode of tumour suppression based on p53 regulation of cystine metabolism, ROS responses and ferroptosis. 10.1038/nature14344
    Ferroptosis: molecular mechanisms and health implications. Tang Daolin,Chen Xin,Kang Rui,Kroemer Guido Cell research Cell death can be executed through different subroutines. Since the description of ferroptosis as an iron-dependent form of non-apoptotic cell death in 2012, there has been mounting interest in the process and function of ferroptosis. Ferroptosis can occur through two major pathways, the extrinsic or transporter-dependent pathway and the intrinsic or enzyme-regulated pathway. Ferroptosis is caused by a redox imbalance between the production of oxidants and antioxidants, which is driven by the abnormal expression and activity of multiple redox-active enzymes that produce or detoxify free radicals and lipid oxidation products. Accordingly, ferroptosis is precisely regulated at multiple levels, including epigenetic, transcriptional, posttranscriptional and posttranslational layers. The transcription factor NFE2L2 plays a central role in upregulating anti-ferroptotic defense, whereas selective autophagy may promote ferroptotic death. Here, we review current knowledge on the integrated molecular machinery of ferroptosis and describe how dysregulated ferroptosis is involved in cancer, neurodegeneration, tissue injury, inflammation, and infection. 10.1038/s41422-020-00441-1
    Ferroptosis: mechanisms, biology and role in disease. Nature reviews. Molecular cell biology The research field of ferroptosis has seen exponential growth over the past few years, since the term was coined in 2012. This unique modality of cell death, driven by iron-dependent phospholipid peroxidation, is regulated by multiple cellular metabolic pathways, including redox homeostasis, iron handling, mitochondrial activity and metabolism of amino acids, lipids and sugars, in addition to various signalling pathways relevant to disease. Numerous organ injuries and degenerative pathologies are driven by ferroptosis. Intriguingly, therapy-resistant cancer cells, particularly those in the mesenchymal state and prone to metastasis, are exquisitely vulnerable to ferroptosis. As such, pharmacological modulation of ferroptosis, via both its induction and its inhibition, holds great potential for the treatment of drug-resistant cancers, ischaemic organ injuries and other degenerative diseases linked to extensive lipid peroxidation. In this Review, we provide a critical analysis of the current molecular mechanisms and regulatory networks of ferroptosis, the potential physiological functions of ferroptosis in tumour suppression and immune surveillance, and its pathological roles, together with a potential for therapeutic targeting. Importantly, as in all rapidly evolving research areas, challenges exist due to misconceptions and inappropriate experimental methods. This Review also aims to address these issues and to provide practical guidelines for enhancing reproducibility and reliability in studies of ferroptosis. Finally, we discuss important concepts and pressing questions that should be the focus of future ferroptosis research. 10.1038/s41580-020-00324-8
    GTP Cyclohydrolase 1/Tetrahydrobiopterin Counteract Ferroptosis through Lipid Remodeling. Kraft Vanessa A N,Bezjian Carla T,Pfeiffer Susanne,Ringelstetter Larissa,Müller Constanze,Zandkarimi Fereshteh,Merl-Pham Juliane,Bao Xuanwen,Anastasov Natasa,Kössl Johanna,Brandner Stefanie,Daniels Jacob D,Schmitt-Kopplin Philippe,Hauck Stefanie M,Stockwell Brent R,Hadian Kamyar,Schick Joel A ACS central science Ferroptosis is an iron-dependent form of regulated cell death linking iron, lipid, and glutathione levels to degenerative processes and tumor suppression. By performing a genome-wide activation screen, we identified a cohort of genes antagonizing ferroptotic cell death, including GTP cyclohydrolase-1 (GCH1) and its metabolic derivatives tetrahydrobiopterin/dihydrobiopterin (BH/BH). Synthesis of BH/BH by GCH1-expressing cells caused lipid remodeling, suppressing ferroptosis by selectively preventing depletion of phospholipids with two polyunsaturated fatty acyl tails. GCH1 expression level in cancer cell lines stratified susceptibility to ferroptosis, in accordance with its expression in human tumor samples. The GCH1-BH-phospholipid axis acts as a master regulator of ferroptosis resistance, controlling endogenous production of the antioxidant BH, abundance of CoQ, and peroxidation of unusual phospholipids with two polyunsaturated fatty acyl tails. This demonstrates a unique mechanism of ferroptosis protection that is independent of the GPX4/glutathione system. 10.1021/acscentsci.9b01063
    Haem oxygenase-1 prevents cell death by regulating cellular iron. Ferris C D,Jaffrey S R,Sawa A,Takahashi M,Brady S D,Barrow R K,Tysoe S A,Wolosker H,Barañano D E,Doré S,Poss K D,Snyder S H Nature cell biology Haem oxygenase-1 (HO1) is a heat-shock protein that is induced by stressful stimuli. Here we demonstrate a cytoprotective role for HO1: cell death produced by serum deprivation, staurosporine or etoposide is markedly accentuated in cells from mice with a targeted deletion of the HO1 gene, and greatly reduced in cells that overexpress HO1. Iron efflux from cells is augmented by HO1 transfection and reduced in HO1-deficient fibroblasts. Iron accumulation in HO1-deficient cells explains their death: iron chelators protect HO1-deficient fibroblasts from cell death. Thus, cytoprotection by HO1 is attributable to its augmentation of iron efflux, reflecting a role for HO1 in modulating intracellular iron levels and regulating cell viability. 10.1038/11072
    Inhibiting Ferroptosis through Disrupting the NCOA4-FTH1 Interaction: A New Mechanism of Action. Fang Yuying,Chen Xiucai,Tan Qingyun,Zhou Huihao,Xu Jun,Gu Qiong ACS central science Ferroptosis is an iron-dependent form of oxidative cell death, and the inhibition of ferroptosis is a promising strategy with which to prevent and treat neurological diseases. Herein we report a new ferroptosis inhibitor with a novel mechanism of action. It is demonstrated that nuclear receptor coactivator 4 (NCOA4), a cargo receptor for ferritinophagy, is the target of . Compound blocks ferroptosis by reducing the amount of bioavailable intracellular ferrous iron through disrupting the NCOA4-FTH1 protein-protein interaction. Further studies indicate that directly binds to recombinant protein NCOA4 and effectively blocks the NCOA4-FTH1 interaction. In a rat model of ischemic stroke, significantly ameliorates the ischemic-refusion injury. With the first ligand , this work reveals that NCOA4 is a promising drug target. Additionally, is the first NCOA4-FTH1 interaction inhibitor. This work paves a new road to the development of ferroptosis inhibitors against neurological diseases. 10.1021/acscentsci.0c01592
    Molecular events contributing to cell death in malignant human hematopoietic cells elicited by an IgG3-avidin fusion protein targeting the transferrin receptor. Ng Patrick P,Helguera Gustavo,Daniels Tracy R,Lomas Simon Z,Rodriguez Jose A,Schiller Gary,Bonavida Benjamin,Morrison Sherie L,Penichet Manuel L Blood We have previously reported that an anti-human transferrin receptor IgG3-avidin fusion protein (anti-hTfR IgG3-Av) inhibits the proliferation of an erythroleukemia-cell line. We have now found that anti-hTfR IgG3-Av also inhibits the proliferation of additional human malignant B and plasma cells. Anti-hTfR IgG3-Av induces internalization and rapid degradation of the TfR. These events can be reproduced in cells treated with anti-hTfR IgG3 cross-linked with a secondary Ab, suggesting that they result from increased TfR cross-linking. Confocal microscopy of cells treated with anti-hTfR IgG3-Av shows that the TfR is directed to an intracellular compartment expressing the lysosomal marker LAMP-1. The degradation of TfR is partially blocked by cysteine protease inhibitors. Furthermore, cells treated with anti-hTfR IgG3-Av exhibit mitochondrial depolarization and activation of caspases 9, 8, and 3. The mitochondrial damage and cell death can be prevented by iron supplementation, but cannot be fully blocked by a pan-caspase inhibitor. These results suggest that anti-hTfR IgG3-Av induces lethal iron deprivation, but the resulting cell death does not solely depend on caspase activation. This report provides insights into the mechanism of cell death induced by anti-TfR Abs such as anti-hTfR IgG3-Av, a molecule that may be useful in the treatment of B-cell malignancies such as multiple myeloma. 10.1182/blood-2006-04-020263
    The Metabolic Underpinnings of Ferroptosis. Zheng Jiashuo,Conrad Marcus Cell metabolism Acute or chronic cellular stress resulting from aberrant metabolic and biochemical processes may trigger a pervasive non-apoptotic form of cell death, generally known as ferroptosis. Ferroptosis is unique among the different cell death modalities, as it has been mostly linked to pathophysiological conditions and because several metabolic pathways, such as (seleno)thiol metabolism, fatty acid metabolism, iron handling, mevalonate pathway, and mitochondrial respiration, directly impinge on the cells' sensitivity toward lipid peroxidation and ferroptosis. Additionally, key cellular redox systems, such as selenium-dependent glutathione peroxidase 4 and the NAD(P)H/ferroptosis suppressor protein-1/ubiquinone axis, are at play that constantly surveil and neutralize oxidative damage to cellular membranes. Since this form of cell death emerges to be the root cause of a number of diseases and since it offers various pharmacologically tractable nodes for therapeutic intervention, there has been overwhelming interest in the last few years aiming for a better molecular understanding of the ferroptotic death process. 10.1016/j.cmet.2020.10.011
    Iron misregulation in the brain: a primary cause of neurodegenerative disorders. Ke Ya,Ming Qian Zhong The Lancet. Neurology High iron concentrations in the brains of patients and the discovery of mutations in the genes associated with iron metabolism in the brain suggest that iron misregulation in the brain plays a part in neuronal death in some neurodegenerative disorders, such as Alzheimer's, Parkinson's, and Huntington's diseases and Hallervorden-Spatz syndrome. Iron misregulation in the brain may have genetic and non-genetic causes. The disrupted expression or function of proteins involved in iron metabolism increases the concentration of iron in the brain. Disturbances can happen at any of several stages in iron metabolism (including uptake and release, storage, intracellular metabolism, and regulation). Increased brain iron triggers a cascade of deleterious events that lead to neurodegeneration. An understanding of the process of iron regulation in the brain, the proteins important in this process, and the effects of iron misregulation could help to treat or prevent neurodegenerative disorders. 10.1016/s1474-4422(03)00353-3
    Endocytic delivery of lipocalin-siderophore-iron complex rescues the kidney from ischemia-reperfusion injury. Mori Kiyoshi,Lee H Thomas,Rapoport Dana,Drexler Ian R,Foster Kirk,Yang Jun,Schmidt-Ott Kai M,Chen Xia,Li Jau Yi,Weiss Stacey,Mishra Jaya,Cheema Faisal H,Markowitz Glenn,Suganami Takayoshi,Sawai Kazutomo,Mukoyama Masashi,Kunis Cheryl,D'Agati Vivette,Devarajan Prasad,Barasch Jonathan The Journal of clinical investigation Neutrophil gelatinase-associated lipocalin (Ngal), also known as siderocalin, forms a complex with iron-binding siderophores (Ngal:siderophore:Fe). This complex converts renal progenitors into epithelial tubules. In this study, we tested the hypothesis that Ngal:siderophore:Fe protects adult kidney epithelial cells or accelerates their recovery from damage. Using a mouse model of severe renal failure, ischemia-reperfusion injury, we show that a single dose of Ngal (10 microg), introduced during the initial phase of the disease, dramatically protects the kidney and mitigates azotemia. Ngal activity depends on delivery of the protein and its siderophore to the proximal tubule. Iron must also be delivered, since blockade of the siderophore with gallium inhibits the rescue from ischemia. The Ngal:siderophore:Fe complex upregulates heme oxygenase-1, a protective enzyme, preserves proximal tubule N-cadherin, and inhibits cell death. Because mouse urine contains an Ngal-dependent siderophore-like activity, endogenous Ngal might also play a protective role. Indeed, Ngal is highly accumulated in the human kidney cortical tubules and in the blood and urine after nephrotoxic and ischemic injury. We reveal what we believe to be a novel pathway of iron traffic that is activated in human and mouse renal diseases, and it provides a unique method for their treatment. 10.1172/JCI23056
    Genetic or pharmacological iron chelation prevents MPTP-induced neurotoxicity in vivo: a novel therapy for Parkinson's disease. Kaur Deepinder,Yantiri Ferda,Rajagopalan Subramanian,Kumar Jyothi,Mo Jun Qin,Boonplueang Rapee,Viswanath Veena,Jacobs Russell,Yang Lichuan,Beal M Flint,DiMonte Dino,Volitaskis Irene,Ellerby Lisa,Cherny Robert A,Bush Ashley I,Andersen Julie K Neuron Studies on postmortem brains from Parkinson's patients reveal elevated iron in the substantia nigra (SN). Selective cell death in this brain region is associated with oxidative stress, which may be exacerbated by the presence of excess iron. Whether iron plays a causative role in cell death, however, is controversial. Here, we explore the effects of iron chelation via either transgenic expression of the iron binding protein ferritin or oral administration of the bioavailable metal chelator clioquinol (CQ) on susceptibility to the Parkinson's-inducing agent 1-methyl-4-phenyl-1,2,3,6-tetrapyridine (MPTP). Reduction in reactive iron by either genetic or pharmacological means was found to be well tolerated in animals in our studies and to result in protection against the toxin, suggesting that iron chelation may be an effective therapy for prevention and treatment of the disease.
    The role of ubiquitination in hepcidin-independent and hepcidin-dependent degradation of ferroportin. De Domenico Ivana,Lo Eric,Yang Baoli,Korolnek Tamara,Hamza Iqbal,Ward Diane McVey,Kaplan Jerry Cell metabolism The iron exporter ferroportin (Fpn) is essential to transfer iron from cells to plasma. Systemic iron homeostasis in vertebrates is regulated by the hepcidin-mediated internalization of Fpn. Here, we demonstrate a second route for Fpn internalization; when cytosolic iron levels are low, Fpn is internalized in a hepcidin-independent manner dependent upon the E3 ubiquitin ligase Nedd4-2 and the Nedd4-2 binding protein Nfdip-1. Retention of cell-surface Fpn through reductions in Nedd4-2 results in cell death through depletion of cytosolic iron. Nedd4-2 is also required for internalization of Fpn in the absence of ferroxidase activity as well as for the entry of hepcidin-induced Fpn into the multivesicular body. C. elegans lacks hepcidin genes, and C. elegans Fpn expressed in mammalian cells is not internalized by hepcidin but is internalized in response to iron deprivation in a Nedd4-2-dependent manner, supporting the hypothesis that Nedd4-2-induced internalization of Fpn is evolutionarily conserved. 10.1016/j.cmet.2011.09.008
    Emerging Strategies of Cancer Therapy Based on Ferroptosis. Shen Zheyu,Song Jibin,Yung Bryant C,Zhou Zijian,Wu Aiguo,Chen Xiaoyuan Advanced materials (Deerfield Beach, Fla.) Ferroptosis, a new form of regulated cell death that is iron- and reactive oxygen species dependent, has attracted much attention in the research communities of biochemistry, oncology, and especially material sciences. Since the first demonstration in 2012, a series of strategies have been developed to induce ferroptosis of cancer cells, including the use of nanomaterials, clinical drugs, experimental compounds, and genes. A plethora of research work has outlined the blueprint of ferroptosis as a new option for cancer therapy. However, the published ferroptosis-related reviews have mainly focused on the mechanisms and pathways of ferroptosis, which motivated this contribution to bridge the gap between biological significance and material design. Therefore, it is timely to summarize the previous efforts on the emerging strategies for inducing ferroptosis and shed light on future directions for using such a tool to fight against cancer. Here, the current strategies of cancer therapy based on ferroptosis will be elaborated, the design considerations and the advantages and limitations are highlighted, and finally a future perspective on this emerging field is given. 10.1002/adma.201704007
    Cytochrome P450 oxidoreductase contributes to phospholipid peroxidation in ferroptosis. Zou Yilong,Li Haoxin,Graham Emily T,Deik Amy A,Eaton John K,Wang Wenyu,Sandoval-Gomez Gerardo,Clish Clary B,Doench John G,Schreiber Stuart L Nature chemical biology Ferroptosis is widely involved in degenerative diseases in various tissues including kidney, liver and brain, and is a targetable vulnerability in multiple primary and therapy-resistant cancers. Accumulation of phospholipid hydroperoxides in cellular membranes is the hallmark and rate-limiting step of ferroptosis; however, the enzymes contributing to lipid peroxidation remain poorly characterized. Using genome-wide, CRISPR-Cas9-mediated suppressor screens, we identify cytochrome P450 oxidoreductase (POR) as necessary for ferroptotic cell death in cancer cells exhibiting inherent and induced susceptibility to ferroptosis. By genetic depletion of POR in cancer cells, we reveal that POR contributes to ferroptosis across a wide range of lineages and cell states, and in response to distinct mechanisms of ferroptosis induction. Using systematic lipidomic profiling, we further map POR's activity to the lipid peroxidation step in ferroptosis. Hence, our work suggests that POR is a key mediator of ferroptosis and potential druggable target for developing antiferroptosis therapeutics. 10.1038/s41589-020-0472-6
    The role of iron regulatory proteins in mammalian iron homeostasis and disease. Rouault Tracey A Nature chemical biology Iron regulatory proteins 1 and 2 (IRP1 and IRP2) are mammalian proteins that register cytosolic iron concentrations and post-transcriptionally regulate expression of iron metabolism genes to optimize cellular iron availability. In iron-deficient cells, IRPs bind to iron-responsive elements (IREs) found in the mRNAs of ferritin, the transferrin receptor and other iron metabolism transcripts, thereby enhancing iron uptake and decreasing iron sequestration. IRP1 registers cytosolic iron status mainly through an iron-sulfur switch mechanism, alternating between an active cytosolic aconitase form with an iron-sulfur cluster ligated to its active site and an apoprotein form that binds IREs. Although IRP2 is homologous to IRP1, IRP2 activity is regulated primarily by iron-dependent degradation through the ubiquitin-proteasomal system in iron-replete cells. Targeted deletions of IRP1 and IRP2 in animals have demonstrated that IRP2 is the chief physiologic iron sensor. The physiological role of the IRP-IRE system is illustrated by (i) hereditary hyperferritinemia cataract syndrome, a human disease in which ferritin L-chain IRE mutations interfere with IRP binding and appropriate translational repression, and (ii) a syndrome of progressive neurodegenerative disease and anemia that develops in adult mice lacking IRP2. The early death of mouse embryos that lack both IRP1 and IRP2 suggests a central role for IRP-mediated regulation in cellular viability. 10.1038/nchembio807
    The FBXL5-IRP2 axis is integral to control of iron metabolism in vivo. Moroishi Toshiro,Nishiyama Masaaki,Takeda Yukiko,Iwai Kazuhiro,Nakayama Keiichi I Cell metabolism Iron-dependent degradation of iron-regulatory protein 2 (IRP2) is a key event for maintenance of an appropriate intracellular concentration of iron. Although FBXL5 (F box and leucine-rich repeat protein 5) is thought to mediate this degradation, the role of FBXL5 in the control of iron homeostasis in vivo has been poorly understood. We have now found that mice deficient in FBXL5 died in utero, associated with excessive iron accumulation. This embryonic mortality was prevented by additional ablation of IRP2, suggesting that impaired IRP2 degradation is primarily responsible for the death of Fbxl5(-)(/-) mice. We also found that liver-specific deletion of Fbxl5 resulted in deregulation of both hepatic and systemic iron homeostasis, leading to the development of steatohepatitis. The liver-specific mutant mice died with acute liver failure when fed a high-iron diet. Thus, our results uncover a major role for FBXL5 in ensuring an appropriate supply of iron to cells. 10.1016/j.cmet.2011.07.011
    SnapShot: Ferroptosis. Hadian Kamyar,Stockwell Brent R Cell Ferroptosis is a regulated form of cell death that occurs when phospholipids with polyunsaturated fatty acyl tails are oxidized in an iron-dependent manner. Research in recent years has uncovered complex cellular networks that induce and suppress lethal lipid peroxidation. This SnapShot provides an overview of ferroptosis-related pathways, including relevant biomolecules and small-molecule modulators regulating them. 10.1016/j.cell.2020.04.039
    Fe-S cluster biosynthesis controls uptake of aminoglycosides in a ROS-less death pathway. Ezraty Benjamin,Vergnes Alexandra,Banzhaf Manuel,Duverger Yohann,Huguenot Allison,Brochado Ana Rita,Su Shu-Yi,Espinosa Leon,Loiseau Laurent,Py Béatrice,Typas Athanasios,Barras Frédéric Science (New York, N.Y.) All bactericidal antibiotics were recently proposed to kill by inducing reactive oxygen species (ROS) production, causing destabilization of iron-sulfur (Fe-S) clusters and generating Fenton chemistry. We find that the ROS response is dispensable upon treatment with bactericidal antibiotics. Furthermore, we demonstrate that Fe-S clusters are required for killing only by aminoglycosides. In contrast to cells, using the major Fe-S cluster biosynthesis machinery, ISC, cells using the alternative machinery, SUF, cannot efficiently mature respiratory complexes I and II, resulting in impendence of the proton motive force (PMF), which is required for bactericidal aminoglycoside uptake. Similarly, during iron limitation, cells become intrinsically resistant to aminoglycosides by switching from ISC to SUF and down-regulating both respiratory complexes. We conclude that Fe-S proteins promote aminoglycoside killing by enabling their uptake. 10.1126/science.1238328
    Energy-stress-mediated AMPK activation inhibits ferroptosis. Lee Hyemin,Zandkarimi Fereshteh,Zhang Yilei,Meena Jitendra Kumar,Kim Jongchan,Zhuang Li,Tyagi Siddhartha,Ma Li,Westbrook Thomas F,Steinberg Gregory R,Nakada Daisuke,Stockwell Brent R,Gan Boyi Nature cell biology Energy stress depletes ATP and induces cell death. Here we identify an unexpected inhibitory role of energy stress on ferroptosis, a form of regulated cell death induced by iron-dependent lipid peroxidation. We found that ferroptotic cell death and lipid peroxidation can be inhibited by treatments that induce or mimic energy stress. Inactivation of AMP-activated protein kinase (AMPK), a sensor of cellular energy status, largely abolishes the protective effects of energy stress on ferroptosis in vitro and on ferroptosis-associated renal ischaemia-reperfusion injury in vivo. Cancer cells with high basal AMPK activation are resistant to ferroptosis and AMPK inactivation sensitizes these cells to ferroptosis. Functional and lipidomic analyses further link AMPK regulation of ferroptosis to AMPK-mediated phosphorylation of acetyl-CoA carboxylase and polyunsaturated fatty acid biosynthesis. Our study demonstrates that energy stress inhibits ferroptosis partly through AMPK and reveals an unexpected coupling between ferroptosis and AMPK-mediated energy-stress signalling. 10.1038/s41556-020-0461-8
    Translocation of iron from lysosomes into mitochondria is a key event during oxidative stress-induced hepatocellular injury. Uchiyama Akira,Kim Jae-Sung,Kon Kazuyoshi,Jaeschke Hartmut,Ikejima Kenichi,Watanabe Sumio,Lemasters John J Hepatology (Baltimore, Md.) UNLABELLED:Iron overload exacerbates various liver diseases. In hepatocytes, a portion of non-heme iron is sequestered in lysosomes and endosomes. The precise mechanisms by which lysosomal iron participates in hepatocellular injury remain uncertain. Here, our aim was to determine the role of intracellular movement of chelatable iron in oxidative stress-induced killing to cultured hepatocytes from C3Heb mice and Sprague-Dawley rats. Mitochondrial polarization and chelatable iron were visualized by confocal microscopy of tetramethylrhodamine methylester (TMRM) and quenching of calcein, respectively. Cell viability and hydroperoxide formation (a measure of lipid peroxidation) were measured fluorometrically using propidium iodide and chloromethyl dihydrodichlorofluorescein, respectively. After collapse of lysosomal/endosomal acidic pH gradients with bafilomycin (50 nM), an inhibitor of the vacuolar proton-pumping adenosine triphosphatase, cytosolic calcein fluorescence became quenched. Deferoxamine mesylate and starch-deferoxamine (1 mM) prevented bafilomycin-induced calcein quenching, indicating that bafilomycin induced release of chelatable iron from lysosomes/endosomes. Bafilomycin also quenched calcein fluorescence in mitochondria, which was blocked by 20 microM Ru360, an inhibitor of the mitochondrial calcium uniporter, consistent with mitochondrial iron uptake by the uniporter. Bafilomycin alone was not sufficient to induce mitochondrial depolarization and cell killing, but in the presence of low-dose tert-butylhydroperoxide (25 microM), bafilomycin enhanced hydroperoxide generation, leading to mitochondrial depolarization and subsequent cell death. CONCLUSION:Taken together, the results are consistent with the conclusion that bafilomycin induces release of chelatable iron from lysosomes/endosomes, which is taken up by mitochondria. Oxidative stress and chelatable iron thus act as two "hits" synergistically promoting toxic radical formation, mitochondrial dysfunction, and cell death. This pathway of intracellular iron translocation is a potential therapeutic target against oxidative stress-mediated hepatotoxicity. 10.1002/hep.22498
    Dysfunction of the heme recycling system in heme oxygenase 1-deficient mice: effects on macrophage viability and tissue iron distribution. Kovtunovych Gennadiy,Eckhaus Michael A,Ghosh Manik C,Ollivierre-Wilson Hayden,Rouault Tracey A Blood To better understand the tissue iron overload and anemia previously reported in a human patient and mice that lack heme oxygenase-1 (HO-1), we studied iron distribution and pathology in HO-1(Hmox1)(-/-) mice. We found that resident splenic and liver macrophages were mostly absent in HO-1(-/-) mice. Erythrophagocytosis caused the death of HO-1(-/-) macrophages in in vitro experiments, supporting the hypothesis that HO-1(-/-) macrophages died of exposure to heme released on erythrophagocytosis. Rupture of HO-1(-/-) macrophages in vivo and release of nonmetabolized heme probably caused tissue inflammation. In the spleen, initial splenic enlargement progressed to red pulp fibrosis, atrophy, and functional hyposplenism in older mice, recapitulating the asplenia of an HO-1-deficient patient. We postulate that the failure of tissue macrophages to remove senescent erythrocytes led to intravascular hemolysis and increased expression of the heme and hemoglobin scavenger proteins, hemopexin and haptoglobin. Lack of macrophages expressing the haptoglobin receptor, CD163, diminished the ability of haptoglobin to neutralize circulating hemoglobin, and iron overload occurred in kidney proximal tubules, which were able to catabolize heme with HO-2. Thus, in HO-1(-/-) mammals, the reduced function and viability of erythrophagocytosing macrophages are the main causes of tissue damage and iron redistribution. 10.1182/blood-2010-03-272138
    Cancer-cell death ironed out. Nature 10.1038/d41586-019-02218-y
    Conditional deletion of ferritin H in mice induces loss of iron storage and liver damage. Darshan Deepak,Vanoaica Liviu,Richman Larry,Beermann Friedrich,Kühn Lukas C Hepatology (Baltimore, Md.) UNLABELLED:Ferritin plays a central role in iron metabolism by acting both as iron storage and a detoxifying protein. We generated a ferritin H allele with loxP sites and studied the conditional ferritin H deletion in adult mice. Ten days after Mx-Cre induced deletion, ferritin H messenger RNA (mRNA) was below 5% in the liver, spleen, and bone marrow of deleted mice compared to control littermates. Mice lost their cellular iron stores indicating the requirement of ferritin H in iron deposition. Serum iron and transferrin saturation were slightly increased and correlated with a two-fold increased liver hepcidin 1 mRNA and a reduced duodenal DcytB mRNA level. Under a normal iron regimen, deleted mice survived for 2 years without visible disadvantage. Mice fed on a high iron diet prior to ferritin H deletion suffered from severe liver damage. Similarly, ferritin H deleted mouse embryonic fibroblasts showed rapid cell death after exposure to iron salt in the medium. This was reversed by wild-type ferritin H but not by a ferritin H mutant lacking ferroxidase activity. Cell death was preceded by an increase in cytoplasmic free iron, reactive oxygen species, and mitochondrial depolarization. CONCLUSION:Our results provide evidence that the iron storage function of ferritin plays a major role in preventing iron-mediated cell and tissue damage. 10.1002/hep.23058
    NUPR1 is a critical repressor of ferroptosis. Liu Jiao,Song Xinxin,Kuang Feimei,Zhang Qiuhong,Xie Yangchun,Kang Rui,Kroemer Guido,Tang Daolin Nature communications Ferroptosis is a type of iron-dependent regulated cell death, representing an emerging disease-modulatory mechanism. Transcription factors play multiple roles in ferroptosis, although the key regulator for ferroptosis in iron metabolism remains elusive. Using NanoString technology, we identify NUPR1, a stress-inducible transcription factor, as a driver of ferroptosis resistance. Mechanistically, NUPR1-mediated LCN2 expression blocks ferroptotic cell death through diminishing iron accumulation and subsequent oxidative damage. Consequently, LCN2 depletion mimics NUPR1 deficiency with respect to ferroptosis induction, whereas transfection-enforced re-expression of LCN2 restores resistance to ferroptosis in NUPR1-deficient cells. Pharmacological or genetic blockade of the NUPR1-LCN2 pathway (using NUPR1 shRNA, LCN2 shRNA, pancreas-specific Lcn2 conditional knockout mice, or the small molecule ZZW-115) increases the activity of the ferroptosis inducer erastin and worsens pancreatitis, in suitable mouse models. These findings suggest a link between NUPR1-regulated iron metabolism and ferroptosis susceptibility. 10.1038/s41467-021-20904-2
    Ferroptosis occurs through an osmotic mechanism and propagates independently of cell rupture. Riegman Michelle,Sagie Liran,Galed Chen,Levin Tom,Steinberg Noah,Dixon Scott J,Wiesner Ulrich,Bradbury Michelle S,Niethammer Philipp,Zaritsky Assaf,Overholtzer Michael Nature cell biology Ferroptosis is a regulated form of necrotic cell death that is caused by the accumulation of oxidized phospholipids, leading to membrane damage and cell lysis. Although other types of necrotic death such as pyroptosis and necroptosis are mediated by active mechanisms of execution, ferroptosis is thought to result from the accumulation of unrepaired cell damage. Previous studies have suggested that ferroptosis has the ability to spread through cell populations in a wave-like manner, resulting in a distinct spatiotemporal pattern of cell death. Here we investigate the mechanism of ferroptosis execution and discover that ferroptotic cell rupture is mediated by plasma membrane pores, similarly to cell lysis in pyroptosis and necroptosis. We further find that intercellular propagation of death occurs following treatment with some ferroptosis-inducing agents, including erastin and C' dot nanoparticles, but not upon direct inhibition of the ferroptosis-inhibiting enzyme glutathione peroxidase 4 (GPX4). Propagation of a ferroptosis-inducing signal occurs upstream of cell rupture and involves the spreading of a cell swelling effect through cell populations in a lipid peroxide- and iron-dependent manner. 10.1038/s41556-020-0565-1
    Mice lacking liver-specific β-catenin develop steatohepatitis and fibrosis after iron overload. Preziosi Morgan E,Singh Sucha,Valore Erika V,Jung Grace,Popovic Branimir,Poddar Minakshi,Nagarajan Shanmugam,Ganz Tomas,Monga Satdarshan P Journal of hepatology BACKGROUND & AIMS:Iron overload disorders such as hereditary hemochromatosis and iron loading anemias are a common cause of morbidity from liver diseases and increase risk of hepatic fibrosis and hepatocellular carcinoma (HCC). Treatment options for iron-induced damage are limited, partly because there is lack of animal models of human disease. Therefore, we investigated the effect of iron overload in liver-specific β-catenin knockout mice (KO), which are susceptible to injury, fibrosis and tumorigenesis following chemical carcinogen exposure. METHODS:Iron overload diet was administered to KO and littermate control (CON) mice for various times. To ameliorate an oxidant-mediated component of tissue injury, N-Acetyl-L-(+)-cysteine (NAC) was added to drinking water of mice on iron overload diet. RESULTS:KO on iron diet (KO +Fe) exhibited remarkable inflammation, followed by steatosis, oxidative stress, fibrosis, regenerating nodules and occurrence of occasional HCC. Increased injury in KO +Fe was associated with activated protein kinase B (AKT), ERK, and NF-κB, along with reappearance of β-catenin and target gene Cyp2e1, which promoted lipid peroxidation and hepatic damage. Addition of NAC to drinking water protected KO +Fe from hepatic steatosis, injury and fibrosis, and prevented activation of AKT, ERK, NF-κB and reappearance of β-catenin. CONCLUSIONS:The absence of hepatic β-catenin predisposes mice to hepatic injury and fibrosis following iron overload, which was reminiscent of hemochromatosis and associated with enhanced steatohepatitis and fibrosis. Disease progression was notably alleviated by antioxidant therapy, which supports its chemopreventive role in the management of chronic iron overload disorders. LAY SUMMARY:Lack of animal models for iron overload disorders makes it hard to study the disease process for improving therapies. Feeding high iron diet to mice that lack the β-catenin gene in liver cells led to increased inflammation followed by fat accumulation, cell death and wound healing that mimicked human disease. Administration of an antioxidant prevented hepatic injury in this model. 10.1016/j.jhep.2017.03.012
    Emerging Mechanisms and Disease Relevance of Ferroptosis. Stockwell Brent R,Jiang Xuejun,Gu Wei Trends in cell biology Cell death is an essential feature of development in multicellular organisms, a critical driver of degenerative diseases, and can be harnessed for treating some cancers. Understanding the mechanisms governing cell death is critical for addressing its role in disease. Similarly, metabolism is essential for normal energy and biomolecule production, and goes awry in many diseases. Metabolism and cell death are tightly linked in the phenomenon of ferroptosis, a form of regulated cell death driven by peroxidation of phospholipids. Glutathione peroxidase 4 (GPX4) uses glutathione to protect cells from ferroptosis by eliminating phospholipid peroxides. Recent data have revealed glutathione/GPX4-independent axes for suppressing ferroptosis, and insight into the regulation of iron and mitochondria in ferroptosis. Ferroptosis has recently been implicated in multiple diseases, and functions as a tumor suppression mechanism. Ferroptosis induction is a promising approach in treating several conditions, including neoplastic diseases. Here, we summarize these recent advances. 10.1016/j.tcb.2020.02.009
    Iron regulatory proteins secure mitochondrial iron sufficiency and function. Galy Bruno,Ferring-Appel Dunja,Sauer Sven W,Kaden Sylvia,Lyoumi Saïd,Puy Herve,Kölker Stefan,Gröne Hermann-Josef,Hentze Matthias W Cell metabolism Mitochondria supply cells with ATP, heme, and iron sulfur clusters (ISC), and mitochondrial energy metabolism involves both heme- and ISC-dependent enzymes. Here, we show that mitochondrial iron supply and function require iron regulatory proteins (IRP), cytosolic RNA-binding proteins that control mRNA translation and stability. Mice lacking both IRP1 and IRP2 in their hepatocytes suffer from mitochondrial iron deficiency and dysfunction associated with alterations of the ISC and heme biosynthetic pathways, leading to liver failure and death. These results uncover a major role of the IRPs in cell biology: to ensure adequate iron supply to the mitochondrion for proper function of this critical organelle. 10.1016/j.cmet.2010.06.007
    Iron sensing and signalling. Evstatiev Rayko,Gasche Christoph Gut Iron deficiency is a common condition increasingly diagnosed and treated by gastroenterologists. The most common presentation of iron deficiency is anaemia; however, it is a systemic disorder affecting multiple aspects of health in various organs. Iron is an essential element, with iron-containing proteins exerting a variety of vital functions, including oxygen transport, cellular respiration, intermediary metabolism, regulation of transcription and DNA repair. Major pathways of iron utilisation and production of iron-containing proteins include iron sulphur cluster biosynthesis, haem synthesis and storage within ferritin. The main site of iron absorption is the small intestine, but most iron is recycled by the monocyte-macrophage system via phagocytosis of senescent erythrocytes. Hepcidin, the key iron-regulating peptide binds to the iron exporter ferroportin and leads to its degradation, thereby inhibiting intestinal iron absorption and cellular export. Hepcidin levels are regulated on a transcriptional level by various stimuli, including transferrin saturation, erythropoietic activity, hypoxia and inflammation. Iron deficiency evokes adaptive responses resulting in alteration of cellular metabolism, changes in gene expression, activation of signalling pathways, cell cycle regulation, differentiation and cell death. Such responses are mediated by a number of iron-sensitive signalling pathways, including the IRE/IRP system, HIF and haem signalling. This review provides a molecular perspective for the clinician and highlights important biological aspects of iron deficiency. 10.1136/gut.2010.214312
    Hepatic reticuloendothelial system cell iron deposition is associated with increased apoptosis in nonalcoholic fatty liver disease. Maliken Bryan D,Nelson James E,Klintworth Heather M,Beauchamp Mary,Yeh Matthew M,Kowdley Kris V Hepatology (Baltimore, Md.) UNLABELLED:The aim of this study was to examine the relationship between the presence of hepatic iron deposition, apoptosis, histologic features, and serum markers of oxidative stress (OS) and cell death in nonalcoholic fatty liver disease (NAFLD). Clinical, biochemical, metabolic, and independent histopathologic assessment was conducted in 83 unselected patients with biopsy-proven NAFLD from a single center. Apoptosis and necrosis in serum was quantified using serum cytokeratin 18 (CK18) M30 and M65 enzyme-linked immunosorbent assays and in liver by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining in situ. Serum malondialdehyde (MDA) and thioredoxin-1 (Trx1) levels were measured to evaluate OS. Presence of reticuloendothelial system (RES) cell iron in the liver was associated with nonalcoholic steatohepatitis (P < 0.05) and increased hepatic TUNEL staining (P = 0.02), as well as increased serum levels of apoptosis-specific (M30; P = 0.013) and total (M65; P = 0.006) CK18 fragments, higher MDA (P = 0.002) and lower antioxidant Trx1 levels (P = 0.012), compared to patients without stainable hepatic iron. NAFLD patients with a hepatocellular (HC) iron staining pattern also had increased serum MDA (P = 0.006), but not M30 CK18 levels or TUNEL staining, compared to subjects without stainable hepatic iron. Patients with iron deposition limited to hepatocytes had a lower proportion of apoptosis-specific M30 fragments relative to total M65 CK18 levels (37% versus ≤25%; P < 0.05). CONCLUSIONS:Presence of iron in liver RES cells is associated with NASH, increased apoptosis, and increased OS. HC iron deposition in NAFLD is also associated with OS and may promote hepatocyte necrosis in this disease. 10.1002/hep.26238
    Global survey of cell death mechanisms reveals metabolic regulation of ferroptosis. Shimada Kenichi,Skouta Rachid,Kaplan Anna,Yang Wan Seok,Hayano Miki,Dixon Scott J,Brown Lewis M,Valenzuela Carlos A,Wolpaw Adam J,Stockwell Brent R Nature chemical biology Apoptosis is one type of programmed cell death. Increasingly, non-apoptotic cell death is recognized as being genetically controlled, or 'regulated'. However, the full extent and diversity of alternative cell death mechanisms remain uncharted. Here we surveyed the landscape of pharmacologically accessible cell death mechanisms. In an examination of 56 caspase-independent lethal compounds, modulatory profiling showed that 10 compounds induced three different types of regulated non-apoptotic cell death. Optimization of one of those ten resulted in the discovery of FIN56, a specific inducer of ferroptosis. Ferroptosis has been found to occur when the lipid-repair enzyme GPX4 is inhibited. FIN56 promoted degradation of GPX4. FIN56 also bound to and activated squalene synthase, an enzyme involved in isoprenoid biosynthesis, independent of GPX4 degradation. These discoveries show that dysregulation of lipid metabolism is associated with ferroptosis. This systematic approach is a means to discover and characterize novel cell death phenotypes. 10.1038/nchembio.2079
    Iron-sulfur cluster deficiency can be sensed by IRP2 and regulates iron homeostasis and sensitivity to ferroptosis independent of IRP1 and FBXL5. Science advances Intracellular iron levels are strictly regulated to support homeostasis and avoid iron-mediated ROS production. Loss of iron-sulfur cluster (ISC) synthesis can increase iron loading and promote cell death by ferroptosis. Iron-responsive element-binding proteins IRP1 and IRP2 posttranscriptionally regulate iron homeostasis. IRP1 binding to target mRNAs is competitively regulated by ISC occupancy. However, IRP2 is principally thought to be regulated at the protein level via E3 ubiquitin ligase FBXL5-mediated degradation. Here, we show that ISC synthesis suppression can activate IRP2 and promote ferroptosis sensitivity via a previously unidentified mechanism. At tissue-level O concentrations, ISC deficiency enhances IRP2 binding to target mRNAs independent of IRP1, FBXL5, and changes in IRP2 protein level. Deletion of both IRP1 and IRP2 abolishes the iron-starvation response, preventing its activation by ISC synthesis inhibition. These findings will inform strategies to manipulate ferroptosis sensitivity and help illuminate the mechanism underlying ISC biosynthesis disorders, such as Friedreich's ataxia. 10.1126/sciadv.abg4302
    Iron Chaperone Poly rC Binding Protein 1 Protects Mouse Liver From Lipid Peroxidation and Steatosis. Hepatology (Baltimore, Md.) BACKGROUND AND AIMS:Iron is essential yet also highly chemically reactive and potentially toxic. The mechanisms that allow cells to use iron safely are not clear; defects in iron management are a causative factor in the cell-death pathway known as ferroptosis. Poly rC binding protein 1 (PCBP1) is a multifunctional protein that serves as a cytosolic iron chaperone, binding and transferring iron to recipient proteins in mammalian cells. Although PCBP1 distributes iron in cells, its role in managing iron in mammalian tissues remains open for study. The liver is highly specialized for iron uptake, utilization, storage, and secretion. APPROACH AND RESULTS:Mice lacking PCBP1 in hepatocytes exhibited defects in liver iron homeostasis with low levels of liver iron, reduced activity of iron enzymes, and misregulation of the cell-autonomous iron regulatory system. These mice spontaneously developed liver disease with hepatic steatosis, inflammation, and degeneration. Transcriptome analysis indicated activation of lipid biosynthetic and oxidative-stress response pathways, including the antiferroptotic mediator, glutathione peroxidase type 4. Although PCBP1-deleted livers were iron deficient, dietary iron supplementation did not prevent steatosis; instead, dietary iron restriction and antioxidant therapy with vitamin E prevented liver disease. PCBP1-deleted hepatocytes exhibited increased labile iron and production of reactive oxygen species (ROS), were hypersensitive to iron and pro-oxidants, and accumulated oxidatively damaged lipids because of the reactivity of unchaperoned iron. CONCLUSIONS:Unchaperoned iron in PCBP1-deleted mouse hepatocytes leads to production of ROS, resulting in lipid peroxidation (LPO) and steatosis in the absence of iron overload. The iron chaperone activity of PCBP1 is therefore critical for limiting the toxicity of cytosolic iron and may be a key factor in preventing the LPO that triggers the ferroptotic cell-death pathway. 10.1002/hep.31328
    Resistance of ferroportin to hepcidin binding causes exocrine pancreatic failure and fatal iron overload. Altamura Sandro,Kessler Regina,Gröne Hermann-Josef,Gretz Norbert,Hentze Matthias W,Galy Bruno,Muckenthaler Martina U Cell metabolism The regulatory axis between the iron hormone hepcidin and its receptor, the iron exporter ferroportin (FPN), is central to iron homeostasis. Mutations preventing hepcidin-mediated degradation of FPN cause systemic iron overload. We have introduced a point mutation (C326S) into the murine Fpn locus, resembling human hereditary hemochromatosis type 4, including elevated plasma iron and ferritin levels, high transferrin saturation, hepatic iron overload, and iron depletion of duodenal enterocytes and reticuloendothelial macrophages. Unlike other mouse models of iron overload, homozygous C326S mice die between 7 and 14 months of age. Pancreatic acinar cells display marked iron accumulation, oxidative damage and degeneration, associated with failure of the exocrine pancreas and severe body weight loss. Rescue experiments reveal iron overload and exocrine pancreatic failure as leading causes of death. This work uncovers the critical importance of the hepcidin-ferroportin regulatory axis for life and unveils the sensitivity of the exocrine pancreas to iron overload. 10.1016/j.cmet.2014.07.007
    Phospholipase iPLAβ averts ferroptosis by eliminating a redox lipid death signal. Nature chemical biology Ferroptosis, triggered by discoordination of iron, thiols and lipids, leads to the accumulation of 15-hydroperoxy (Hp)-arachidonoyl-phosphatidylethanolamine (15-HpETE-PE), generated by complexes of 15-lipoxygenase (15-LOX) and a scaffold protein, phosphatidylethanolamine (PE)-binding protein (PEBP)1. As the Ca-independent phospholipase Aβ (iPLAβ, PLA2G6 or PNPLA9 gene) can preferentially hydrolyze peroxidized phospholipids, it may eliminate the ferroptotic 15-HpETE-PE death signal. Here, we demonstrate that by hydrolyzing 15-HpETE-PE, iPLAβ averts ferroptosis, whereas its genetic or pharmacological inactivation sensitizes cells to ferroptosis. Given that PLA2G6 mutations relate to neurodegeneration, we examined fibroblasts from a patient with a Parkinson's disease (PD)-associated mutation (fPD) and found selectively decreased 15-HpETE-PE-hydrolyzing activity, 15-HpETE-PE accumulation and elevated sensitivity to ferroptosis. CRISPR-Cas9-engineered Pnpla9 mice exhibited progressive parkinsonian motor deficits and 15-HpETE-PE accumulation. Elevated 15-HpETE-PE levels were also detected in midbrains of rotenone-infused parkinsonian rats and α-synuclein-mutant Snca mice, with decreased iPLAβ expression and a PD-relevant phenotype. Thus, iPLAβ is a new ferroptosis regulator, and its mutations may be implicated in PD pathogenesis. 10.1038/s41589-020-00734-x
    Redox lipid reprogramming commands susceptibility of macrophages and microglia to ferroptotic death. Kapralov Alexandr A,Yang Qin,Dar Haider H,Tyurina Yulia Y,Anthonymuthu Tamil S,Kim Rina,St Croix Claudette M,Mikulska-Ruminska Karolina,Liu Bing,Shrivastava Indira H,Tyurin Vladimir A,Ting Hsiu-Chi,Wu Yijen L,Gao Yuan,Shurin Galina V,Artyukhova Margarita A,Ponomareva Liubov A,Timashev Peter S,Domingues Rosario M,Stoyanovsky Detcho A,Greenberger Joel S,Mallampalli Rama K,Bahar Ivet,Gabrilovich Dmitry I,Bayır Hülya,Kagan Valerian E Nature chemical biology Ferroptotic death is the penalty for losing control over three processes-iron metabolism, lipid peroxidation and thiol regulation-that are common in the pro-inflammatory environment where professional phagocytes fulfill their functions and yet survive. We hypothesized that redox reprogramming of 15-lipoxygenase (15-LOX) during the generation of pro-ferroptotic signal 15-hydroperoxy-eicosa-tetra-enoyl-phosphatidylethanolamine (15-HpETE-PE) modulates ferroptotic endurance. Here, we have discovered that inducible nitric oxide synthase (iNOS)/NO-enrichment of activated M1 (but not alternatively activated M2) macrophages/microglia modulates susceptibility to ferroptosis. Genetic or pharmacologic depletion/inactivation of iNOS confers sensitivity on M1 cells, whereas NO donors empower resistance of M2 cells to ferroptosis. In vivo, M1 phagocytes, in comparison to M2 phagocytes, exert higher resistance to pharmacologically induced ferroptosis. This resistance is diminished in iNOS-deficient cells in the pro-inflammatory conditions of brain trauma or the tumour microenvironment. The nitroxygenation of eicosatetraenoyl (ETE)-PE intermediates and oxidatively truncated species by NO donors and/or suppression of NO production by iNOS inhibitors represent a novel redox mechanism of regulation of ferroptosis in pro-inflammatory conditions. 10.1038/s41589-019-0462-8
    The lysosome as a master regulator of iron metabolism. Rizzollo Francesca,More Sanket,Vangheluwe Peter,Agostinis Patrizia Trends in biochemical sciences Intracellular iron fulfills crucial cellular processes, including DNA synthesis and mitochondrial metabolism, but also mediates ferroptosis, a regulated form of cell death driven by lipid-based reactive oxygen species (ROS). Beyond their established role in degradation and recycling, lysosomes occupy a central position in iron homeostasis and integrate metabolic and cell death signals emanating from different subcellular sites. We discuss the central role of the lysosome in preserving iron homeostasis and provide an integrated outlook of the regulatory circuits coupling the lysosomal system to the control of iron trafficking, interorganellar crosstalk, and ferroptosis induction. We also discuss novel studies unraveling how deregulated lysosomal iron-handling functions contribute to cancer, neurodegeneration, and viral infection, and can be harnessed for therapeutic interventions. 10.1016/j.tibs.2021.07.003
    Regional brain iron associated with deterioration in Alzheimer's disease: A large cohort study and theoretical significance. Ayton Scott,Portbury Stuart,Kalinowski Pawel,Agarwal Puja,Diouf Ibrahima,Schneider Julie A,Morris Martha Clare,Bush Ashley I Alzheimer's & dementia : the journal of the Alzheimer's Association OBJECTIVE:This paper is a proposal for an update of the iron hypothesis of Alzheimer's disease (AD), based on large-scale emerging evidence. BACKGROUND:Iron featured historically early in AD research efforts for its involvement in the amyloid and tau proteinopathies, APP processing, genetics, and one clinical trial, yet iron neurochemistry remains peripheral in mainstream AD research. Much of the effort investigating iron in AD has focused on the potential for iron to provoke the onset of disease, by promoting proteinopathy though increased protein expression, phosphorylation, and aggregation. NEW/UPDATED HYPOTHESIS:We provide new evidence from a large post mortem cohort that brain iron levels within the normal range were associated with accelerated ante mortem disease progression in cases with underlying proteinopathic neuropathology. These results corroborate recent findings that argue for an additional downstream role for iron as an effector of neurodegeneration, acting independently of tau or amyloid pathologies. We hypothesize that the level of tissue iron is a trait that dictates the probability of neurodegeneration in AD by ferroptosis, a regulated cell death pathway that is initiated by signals such as glutathione depletion and lipid peroxidation. MAJOR CHALLENGES FOR THE HYPOTHESIS:While clinical biomarkers of ferroptosis are still in discovery, the demonstration of additional ferroptotic correlates (genetic or biomarker derived) of disease progression is required to test this hypothesis. The genes implicated in familial AD are not known to influence ferroptosis, although recent reports on APP mutations and apolipoprotein E allele (APOE) have shown impact on cellular iron retention. Familial AD mutations will need to be tested for their impact on ferroptotic vulnerability. Ultimately, this hypothesis will be substantiated, or otherwise, by a clinical trial of an anti-ferroptotic/iron compound in AD patients. LINKAGE TO OTHER MAJOR THEORIES:Iron has historically been linked to the amyloid and tau proteinopathies of AD. Tau, APP, and apoE have been implicated in physiological iron homeostasis in the brain. Iron is biochemically the origin of most chemical radicals generated in biochemistry and thus closely associated with the oxidative stress theory of AD. Iron accumulation is also a well-established consequence of aging and inflammation, which are major theories of disease pathogenesis. 10.1002/alz.12282
    Iron expulsion by exosomes drives ferroptosis resistance. Strzyz Paulina Nature reviews. Molecular cell biology 10.1038/s41580-019-0195-2
    Therapeutic targeting of oxygen-sensing prolyl hydroxylases abrogates ATF4-dependent neuronal death and improves outcomes after brain hemorrhage in several rodent models. Karuppagounder Saravanan S,Alim Ishraq,Khim Soah J,Bourassa Megan W,Sleiman Sama F,John Roseleen,Thinnes Cyrille C,Yeh Tzu-Lan,Demetriades Marina,Neitemeier Sandra,Cruz Dana,Gazaryan Irina,Killilea David W,Morgenstern Lewis,Xi Guohua,Keep Richard F,Schallert Timothy,Tappero Ryan V,Zhong Jian,Cho Sunghee,Maxfield Frederick R,Holman Theodore R,Culmsee Carsten,Fong Guo-Hua,Su Yijing,Ming Guo-li,Song Hongjun,Cave John W,Schofield Christopher J,Colbourne Frederick,Coppola Giovanni,Ratan Rajiv R Science translational medicine Disability or death due to intracerebral hemorrhage (ICH) is attributed to blood lysis, liberation of iron, and consequent oxidative stress. Iron chelators bind to free iron and prevent neuronal death induced by oxidative stress and disability due to ICH, but the mechanisms for this effect remain unclear. We show that the hypoxia-inducible factor prolyl hydroxylase domain (HIF-PHD) family of iron-dependent, oxygen-sensing enzymes are effectors of iron chelation. Molecular reduction of the three HIF-PHD enzyme isoforms in the mouse striatum improved functional recovery after ICH. A low-molecular-weight hydroxyquinoline inhibitor of the HIF-PHD enzymes, adaptaquin, reduced neuronal death and behavioral deficits after ICH in several rodent models without affecting total iron or zinc distribution in the brain. Unexpectedly, protection from oxidative death in vitro or from ICH in vivo by adaptaquin was associated with suppression of activity of the prodeath factor ATF4 rather than activation of an HIF-dependent prosurvival pathway. Together, these findings demonstrate that brain-specific inactivation of the HIF-PHD metalloenzymes with the blood-brain barrier-permeable inhibitor adaptaquin can improve functional outcomes after ICH in several rodent models. 10.1126/scitranslmed.aac6008
    Reactivity-Based Probe of the Iron(II)-Dependent Interactome Identifies New Cellular Modulators of Ferroptosis. Chen Ying-Chu,Oses-Prieto Juan A,Pope Lauren E,Burlingame Alma L,Dixon Scott J,Renslo Adam R Journal of the American Chemical Society Ferroptosis is an iron-dependent form of cell death resulting from loss or inhibition of cellular machinery that protects from the accumulation of lipid hydroperoxides. Ferroptosis likely serves a tumor suppressing function in normal cellular homeostasis, but certain cancers exploit and become highly dependent on specific nodes of the pathway, presumably to survive under conditions of increased oxidative stress and elevated labile ferrous iron levels. Here we introduce Ferroptosis Inducing Peroxide for Chemoproteomics-1 (FIPC-1), a reactivity-based probe that couples Fenton-type reaction with ferrous iron to subsequent protein labeling via concomitant carbon-centered radical generation. We show that FIPC-1 induces ferroptosis in susceptible cell types and labels cellular proteins in an iron-dependent fashion. Use of FIPC-1 in a quantitative chemoproteomics workflow reproducibly enriched protein targets in the thioredoxin, oxidoreductase, and protein disulfide isomerase (PDI) families, among others. In further interrogating the saturable targets of FIPC-1, we identified the PDI family member P4HB and the functionally uncharacterized protein NT5DC2, a member of the haloacid dehalogenase (HAD) superfamily, as previously unrecognized modulators of ferroptosis. Knockdown of these target genes sensitized cells to known ferroptosis inducers, while PACMA31, a previously reported inhibitor of P4HB, directly induced ferroptosis and was highly synergistic with erastin. Overall, this study introduces a new reactivity-based probe of the ferrous iron-dependent interactome and uncovers new targets for the therapeutic modulation of ferroptosis. 10.1021/jacs.0c06709
    HIF-2α activation potentiates oxidative cell death in colorectal cancers by increasing cellular iron. The Journal of clinical investigation Hypoxia is a hallmark of solid tumors that promotes cell growth, survival, and metastasis and confers resistance to chemo and radiotherapies. Hypoxic responses are largely mediated by the transcription factors hypoxia-inducible factor 1α (HIF-1α) and HIF-2α. Our work demonstrates that HIF-2α is essential for colorectal cancer (CRC) progression. However, targeting hypoxic cells is difficult, and tumors rapidly acquire resistance to inhibitors of HIF-2α. To overcome this limitation, we performed a small molecule screen to identify HIF-2α-dependent vulnerabilities. Several known ferroptosis activators and dimethyl fumarate (DMF), a cell-permeable mitochondrial metabolite derivative, led to selective synthetic lethality in HIF-2α-expressing tumor enteroids. Our work demonstrated that HIF-2α integrated 2 independent forms of cell death via regulation of cellular iron and oxidation. First, activation of HIF-2α upregulated lipid and iron regulatory genes in CRC cells and colon tumors in mice and led to a ferroptosis-susceptible cell state. Second, via an iron-dependent, lipid peroxidation-independent pathway, HIF-2α activation potentiated ROS via irreversible cysteine oxidation and enhanced cell death. Inhibition or knockdown of HIF-2α decreased ROS and resistance to oxidative cell death in vitro and in vivo. Our results demonstrated a mechanistic vulnerability in cancer cells that were dependent on HIF-2α that can be leveraged for CRC treatment. 10.1172/JCI143691
    The roles of iron and HFE genotype in neurological diseases. Kim Yunsung,Connor James R Molecular aspects of medicine Iron accumulation is a recurring pathological phenomenon in many neurological diseases including Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis, and others. Iron is essential for normal development and functions of the brain; however, excess redox-active iron can also lead to oxidative damage and cell death. Especially for terminally differentiated cells like neurons, regulation of reactive oxygen species is critical for cell viability. As a result, cellular iron level is tightly regulated. Although iron accumulation related to neurological diseases has been well documented, the pathoetiological contributions of the homeostatic iron regulator (HFE), which controls cellular iron uptake, is less understood. Furthermore, a common HFE variant, H63D HFE, has been identified as a modifier of multiple neurological diseases. This review will discuss the roles of iron and HFE in the brain as well as their impact on various disease processes. 10.1016/j.mam.2020.100867
    System xC- is a mediator of microglial function and its deletion slows symptoms in amyotrophic lateral sclerosis mice. Mesci Pinar,Zaïdi Sakina,Lobsiger Christian S,Millecamps Stéphanie,Escartin Carole,Seilhean Danielle,Sato Hideyo,Mallat Michel,Boillée Séverine Brain : a journal of neurology Amyotrophic lateral sclerosis is the most common adult-onset motor neuron disease and evidence from mice expressing amyotrophic lateral sclerosis-causing SOD1 mutations suggest that neurodegeneration is a non-cell autonomous process where microglial cells influence disease progression. However, microglial-derived neurotoxic factors still remain largely unidentified in amyotrophic lateral sclerosis. With excitotoxicity being a major mechanism proposed to cause motor neuron death in amyotrophic lateral sclerosis, our hypothesis was that excessive glutamate release by activated microglia through their system [Formula: see text] (a cystine/glutamate antiporter with the specific subunit xCT/Slc7a11) could contribute to neurodegeneration. Here we show that xCT expression is enriched in microglia compared to total mouse spinal cord and absent from motor neurons. Activated microglia induced xCT expression and during disease, xCT levels were increased in both spinal cord and isolated microglia from mutant SOD1 amyotrophic lateral sclerosis mice. Expression of xCT was also detectable in spinal cord post-mortem tissues of patients with amyotrophic lateral sclerosis and correlated with increased inflammation. Genetic deletion of xCT in mice demonstrated that activated microglia released glutamate mainly through system [Formula: see text]. Interestingly, xCT deletion also led to decreased production of specific microglial pro-inflammatory/neurotoxic factors including nitric oxide, TNFa and IL6, whereas expression of anti-inflammatory/neuroprotective markers such as Ym1/Chil3 were increased, indicating that xCT regulates microglial functions. In amyotrophic lateral sclerosis mice, xCT deletion surprisingly led to earlier symptom onset but, importantly, this was followed by a significantly slowed progressive disease phase, which resulted in more surviving motor neurons. These results are consistent with a deleterious contribution of microglial-derived glutamate during symptomatic disease. Therefore, we show that system [Formula: see text] participates in microglial reactivity and modulates amyotrophic lateral sclerosis motor neuron degeneration, revealing system [Formula: see text] inactivation, as a potential approach to slow amyotrophic lateral sclerosis disease progression after onset of clinical symptoms. 10.1093/brain/awu312
    Functional reconstitution of mitochondrial Fe/S cluster synthesis on Isu1 reveals the involvement of ferredoxin. Webert Holger,Freibert Sven-Andreas,Gallo Angelo,Heidenreich Torsten,Linne Uwe,Amlacher Stefan,Hurt Ed,Mühlenhoff Ulrich,Banci Lucia,Lill Roland Nature communications Maturation of iron-sulphur (Fe/S) proteins involves complex biosynthetic machinery. In vivo synthesis of [2Fe-2S] clusters on the mitochondrial scaffold protein Isu1 requires the cysteine desulphurase complex Nfs1-Isd11, frataxin, ferredoxin Yah1 and its reductase Arh1. The roles of Yah1-Arh1 have remained enigmatic, because they are not required for in vitro Fe/S cluster assembly. Here, we reconstitute [2Fe-2S] cluster synthesis on Isu1 in a reaction depending on Nfs1-Isd11, frataxin, Yah1, Arh1 and NADPH. Unlike in the bacterial system, frataxin is an essential part of Fe/S cluster biosynthesis and is required simultaneously and stoichiometrically to Yah1. Reduced but not oxidized Yah1 tightly interacts with apo-Isu1 indicating a dynamic interaction between Yah1-apo-Isu1. Nuclear magnetic resonance structural studies identify the Yah1-apo-Isu1 interaction surface and suggest a pathway for electron flow from reduced ferredoxin to Isu1. Together, our study defines the molecular function of the ferredoxin Yah1 and its human orthologue FDX2 in mitochondrial Fe/S cluster synthesis. 10.1038/ncomms6013
    Melatonin enhances antioxidant action of alpha-tocopherol and ascorbate against NADPH- and iron-dependent lipid peroxidation in human placental mitochondria. Milczarek Ryszard,Hallmann Anna,Sokołowska Ewa,Kaletha Krystian,Klimek Jerzy Journal of pineal research Human placental mitochondria might be a significant source of NADPH- and iron-dependent production of reactive oxygen species (ROS). Preeclampsia is believed to be a consequence of overproduction of ROS in human placenta. The experimental results presented here show that melatonin inhibits NADPH- and iron-dependent lipid peroxidation of human placental mitochondria in a concentration-dependent manner. At 1.5 mm concentration, melatonin suppressed this process nearly completely. Melatonin does not influence significantly the iron oxidation at this conditions, indicating that free radical scavenging rather than metal-chelating phenomenon is the basis of its antioxidant action. The fact of inhibition of lipid peroxidation by melatonin at conditions excluding iron participation also supports this hypothesis. Elucidation of the nature of common interaction among melatonin, ascorbate, and alpha-tocopherol in human placental mitochondria was the main aim of this study. In presence of 90 mum ascorbate, the inhibition of lipid peroxidation by melatonin was strong and had a feature of synergistic interaction. At presence of 30 mum ascorbate, which stimulated lipid peroxidation, melatonin caused a loss of pro-oxidant effect of ascorbate. While the interaction of melatonin with ascorbate indicated synergism, the joint action of melatonin and alpha-tocopherol was additive. When all three antioxidants were applied together, the strongest inhibition of lipid peroxidation was observed. The experimental results presented here indicated that melatonin could be considered as an effective component of antioxidant treatment of preeclampsia, allowing the use of reduced doses of vitamin C and E owing to elevated efficiency of their antioxidant activity in placenta when used in combination. 10.1111/j.1600-079X.2010.00779.x
    Glial lipid droplets and ROS induced by mitochondrial defects promote neurodegeneration. Liu Lucy,Zhang Ke,Sandoval Hector,Yamamoto Shinya,Jaiswal Manish,Sanz Elisenda,Li Zhihong,Hui Jessica,Graham Brett H,Quintana Albert,Bellen Hugo J Cell Reactive oxygen species (ROS) and mitochondrial defects in neurons are implicated in neurodegenerative disease. Here, we find that a key consequence of ROS and neuronal mitochondrial dysfunction is the accumulation of lipid droplets (LD) in glia. In Drosophila, ROS triggers c-Jun-N-terminal Kinase (JNK) and Sterol Regulatory Element Binding Protein (SREBP) activity in neurons leading to LD accumulation in glia prior to or at the onset of neurodegeneration. The accumulated lipids are peroxidated in the presence of ROS. Reducing LD accumulation in glia and lipid peroxidation via targeted lipase overexpression and/or lowering ROS significantly delays the onset of neurodegeneration. Furthermore, a similar pathway leads to glial LD accumulation in Ndufs4 mutant mice with neuronal mitochondrial defects, suggesting that LD accumulation following mitochondrial dysfunction is an evolutionarily conserved phenomenon, and represents an early, transient indicator and promoter of neurodegenerative disease. 10.1016/j.cell.2014.12.019
    Iron overload is accompanied by mitochondrial and lysosomal dysfunction in WDR45 mutant cells. Seibler Philip,Burbulla Lena F,Dulovic Marija,Zittel Simone,Heine Johanne,Schmidt Thomas,Rudolph Franziska,Westenberger Ana,Rakovic Aleksandar,Münchau Alexander,Krainc Dimitri,Klein Christine Brain : a journal of neurology Beta-propeller protein-associated neurodegeneration is a subtype of monogenic neurodegeneration with brain iron accumulation caused by de novo mutations in WDR45. The WDR45 protein functions as a beta-propeller scaffold and plays a putative role in autophagy through its interaction with phospholipids and autophagy-related proteins. Loss of WDR45 function due to disease-causing mutations has been linked to defects in autophagic flux in patient and animal cells. However, the role of WDR45 in iron homeostasis remains elusive. Here we studied patient-specific WDR45 mutant fibroblasts and induced pluripotent stem cell-derived midbrain neurons. Our data demonstrated that loss of WDR45 increased cellular iron levels and oxidative stress, accompanied by mitochondrial abnormalities, autophagic defects, and diminished lysosomal function. Restoring WDR45 levels partially rescued oxidative stress and the susceptibility to iron treatment, and activation of autophagy reduced the observed iron overload in WDR45 mutant cells. Our data suggest that iron-containing macromolecules and organelles cannot effectively be degraded through the lysosomal pathway due to loss of WDR45 function. 10.1093/brain/awy230
    Autophagy promotes ferroptosis by degradation of ferritin. Hou Wen,Xie Yangchun,Song Xinxin,Sun Xiaofang,Lotze Michael T,Zeh Herbert J,Kang Rui,Tang Daolin Autophagy Macroautophagy/autophagy is an evolutionarily conserved degradation pathway that maintains homeostasis. Ferroptosis, a novel form of regulated cell death, is characterized by a production of reactive oxygen species from accumulated iron and lipid peroxidation. However, the relationship between autophagy and ferroptosis at the genetic level remains unclear. Here, we demonstrated that autophagy contributes to ferroptosis by degradation of ferritin in fibroblasts and cancer cells. Knockout or knockdown of Atg5 (autophagy-related 5) and Atg7 limited erastin-induced ferroptosis with decreased intracellular ferrous iron levels, and lipid peroxidation. Remarkably, NCOA4 (nuclear receptor coactivator 4) was a selective cargo receptor for the selective autophagic turnover of ferritin (namely ferritinophagy) in ferroptosis. Consistently, genetic inhibition of NCOA4 inhibited ferritin degradation and suppressed ferroptosis. In contrast, overexpression of NCOA4 increased ferritin degradation and promoted ferroptosis. These findings provide novel insight into the interplay between autophagy and regulated cell death. 10.1080/15548627.2016.1187366
    BECN1 is a new driver of ferroptosis. Kang Rui,Zhu Shan,Zeh Herbert J,Klionsky Daniel J,Tang Daolin Autophagy Ferroptosis is a form of regulated cell death caused by iron accumulation and oxidative injury. BECN1 is a key regulator of macroautophagy/autophagy, a catabolic process of degradation induced by starvation or other stressors. Our recent findings reveal a novel alternative mechanism by which BECN1 can promote ferroptosis through the regulation of activity of the cysteine and glutamate antiporter system x in cancer cells. BECN1-dependent autophagy requires the formation of the BECN1-containing class III phosphatidylinositol 3-kinase (PtdIns3K) complex, whereas BECN1-dependent ferroptosis requires the formation of a BECN1-SLC7A11 complex. Furthermore, AMP-activated protein kinase (AMPK) is required for BECN1 phosphorylation to trigger formation of the BECN1-SLC7A11 complex in the process of inhibiting system x activity and inducing lipid peroxidation. These findings suggest that the autophagy-dependent and -independent functions of BECN1 play distinct roles in regulated cell death. 10.1080/15548627.2018.1513758
    Ferroptosis: bug or feature? Dixon Scott J Immunological reviews Ferroptosis is an iron-dependent, oxidative form of non-apoptotic cell death. This form of cell death does not share morphological, biochemical, or genetic similarities with classic necrosis, necroptosis, parthanatos, or other forms of non-apoptotic cell death. Ferroptosis can be triggered by depleting the cell of the amino acid cysteine, or by inhibiting the phospholipid hydroperoxidase glutathione peroxidase 4 (GPX4). Why certain stimuli trigger ferroptosis instead of another form of cell death, and whether this process could be adaptive in vivo, are two major unanswered questions concerning this process. Emerging evidence and consideration of related non-apoptotic pathways suggest that ferroptosis could be an adaptive process, albeit one regulated and executed in a manner very different from apoptosis and other forms of cell death. 10.1111/imr.12533
    Ferroptosis Inhibition: Mechanisms and Opportunities. Angeli Jose Pedro Friedmann,Shah Ron,Pratt Derek A,Conrad Marcus Trends in pharmacological sciences The past decade has yielded tremendous insights into how cells die. This has come with our understanding that several distinct forms of cell death are encompassed under the umbrella term necrosis. Among these distinct forms of regulated necrotic cell death, ferroptosis has attracted considerable attention owing to its putative involvement in diverse pathophysiological processes. A key feature of the ferroptosis process is the requirement of phospholipid peroxidation, a process that has been linked with several human pathologies. Now with the establishment of a connection between lipid peroxidation and a distinctive cell death pathway, the search for new small molecules able to suppress lipid peroxidation has gained momentum and may yield novel cytoprotective strategies. We review here advances in our understanding of the ferroptotic process and summarize the development of lipid peroxidation inhibitors with the ultimate goal of suppressing ferroptosis-relevant cell death and related pathologies. 10.1016/j.tips.2017.02.005
    A major role for ferroptosis in -induced cell death and tissue necrosis. Amaral Eduardo P,Costa Diego L,Namasivayam Sivaranjani,Riteau Nicolas,Kamenyeva Olena,Mittereder Lara,Mayer-Barber Katrin D,Andrade Bruno B,Sher Alan The Journal of experimental medicine Necrotic cell death during (Mtb) infection is considered host detrimental since it facilitates mycobacterial spread. Ferroptosis is a type of regulated necrosis induced by accumulation of free iron and toxic lipid peroxides. We observed that Mtb-induced macrophage necrosis is associated with reduced levels of glutathione and glutathione peroxidase-4 (Gpx4), along with increased free iron, mitochondrial superoxide, and lipid peroxidation, all of which are important hallmarks of ferroptosis. Moreover, necrotic cell death in Mtb-infected macrophage cultures was suppressed by ferrostatin-1 (Fer-1), a well-characterized ferroptosis inhibitor, as well as by iron chelation. Additional experiments in vivo revealed that pulmonary necrosis in acutely infected mice is associated with reduced Gpx4 expression as well as increased lipid peroxidation and is likewise suppressed by Fer-1 treatment. Importantly, Fer-1-treated infected animals also exhibited marked reductions in bacterial load. Together, these findings implicate ferroptosis as a major mechanism of necrosis in Mtb infection and as a target for host-directed therapy of tuberculosis. 10.1084/jem.20181776
    Revisiting the intersection of amyloid, pathologically modified tau and iron in Alzheimer's disease from a ferroptosis perspective. Derry Paul J,Hegde Muralidhar L,Jackson George R,Kayed Rakez,Tour James M,Tsai Ah-Lim,Kent Thomas A Progress in neurobiology The complexity of Alzheimer's disease (AD) complicates the search for effective treatments. While the key roles of pathologically modified proteins has occupied a central role in hypotheses of the pathophysiology, less attention has been paid to the potential role for transition metals overload, subsequent oxidative stress, and tissue injury. The association of transition metals, the major focus heretofore iron and amyloid, the same can now be said for the likely pathogenic microtubular associated tau (MAPT). This review discusses the interplay between iron, pathologically modified tau and oxidative stress, and connects many related discoveries. Basic principles of the transition to pathological MAPT are discussed. Iron, its homeostatic mechanisms, the recently described phenomenon of ferroptosis and purported, although still controversial roles in AD are reviewed as well as considerations to overcome existing hurdles of iron-targeted therapeutic avenues that have been attempted in AD. We summarize the involvement of multiple pathological pathways at different disease stages of disease progression that supports the potential for a combinatorial treatment strategy targeting multiple factors. 10.1016/j.pneurobio.2019.101716
    Ferrostatins inhibit oxidative lipid damage and cell death in diverse disease models. Skouta Rachid,Dixon Scott J,Wang Jianlin,Dunn Denise E,Orman Marina,Shimada Kenichi,Rosenberg Paul A,Lo Donald C,Weinberg Joel M,Linkermann Andreas,Stockwell Brent R Journal of the American Chemical Society Ferrostatin-1 (Fer-1) inhibits ferroptosis, a form of regulated, oxidative, nonapoptotic cell death. We found that Fer-1 inhibited cell death in cellular models of Huntington's disease (HD), periventricular leukomalacia (PVL), and kidney dysfunction; Fer-1 inhibited lipid peroxidation, but not mitochondrial reactive oxygen species formation or lysosomal membrane permeability. We developed a mechanistic model to explain the activity of Fer-1, which guided the development of ferrostatins with improved properties. These studies suggest numerous therapeutic uses for ferrostatins, and that lipid peroxidation mediates diverse disease phenotypes. 10.1021/ja411006a
    Cellular protection using Flt3 and PI3Kα inhibitors demonstrates multiple mechanisms of oxidative glutamate toxicity. Kang Yunyi,Tiziani Stefano,Park Goonho,Kaul Marcus,Paternostro Giovanni Nature communications Glutamate-induced oxidative stress is a major contributor to neurodegenerative diseases. Here, we identify small-molecule inhibitors of this process. We screen a kinase inhibitor library on neuronal cells and identify Flt3 and PI3Kα inhibitors as potent protectors against glutamate toxicity. Both inhibitors prevented reactive oxygen species (ROS) generation, mitochondrial hyperpolarization and lipid peroxidation in neuronal cells, but they do so by distinct molecular mechanisms. The PI3Kα inhibitor protects cells by inducing partial restoration of depleted glutathione levels and accumulation of intracellular amino acids, whereas the Flt3 inhibitor prevents lipid peroxidation, a key mechanism of glutamate-mediated toxicity. We also demonstrate that glutamate toxicity involves a combination of ferroptosis, necrosis and AIF-dependent apoptosis. We confirm the protective effect by using multiple inhibitors of these kinases and multiple cell types. Our results not only identify compounds that protect against glutamate-stimulated oxidative stress, but also provide new insights into the mechanisms of glutamate toxicity in neurons. 10.1038/ncomms4672
    Tau-mediated iron export prevents ferroptotic damage after ischemic stroke. Tuo Q-Z,Lei P,Jackman K A,Li X-L,Xiong H,Li X-L,Liuyang Z-Y,Roisman L,Zhang S-T,Ayton S,Wang Q,Crouch P J,Ganio K,Wang X-C,Pei L,Adlard P A,Lu Y-M,Cappai R,Wang J-Z,Liu R,Bush A I Molecular psychiatry Functional failure of tau contributes to age-dependent, iron-mediated neurotoxicity, and as iron accumulates in ischemic stroke tissue, we hypothesized that tau failure may exaggerate ischemia-reperfusion-related toxicity. Indeed, unilateral, transient middle cerebral artery occlusion (MCAO) suppressed hemispheric tau and increased iron levels in young (3-month-old) mice and rats. Wild-type mice were protected by iron-targeted interventions: ceruloplasmin and amyloid precursor protein ectodomain, as well as ferroptosis inhibitors. At this age, tau-knockout mice did not express elevated brain iron and were protected against hemispheric reperfusion injury following MCAO, indicating that tau suppression may prevent ferroptosis. However, the accelerated age-dependent brain iron accumulation that occurs in tau-knockout mice at 12 months of age negated the protective benefit of tau suppression against MCAO-induced focal cerebral ischemia-reperfusion injury. The protective benefit of tau knockout was revived in older mice by iron-targeting interventions. These findings introduce tau-iron interaction as a pleiotropic modulator of ferroptosis and ischemic stroke outcome. 10.1038/mp.2017.171
    Glutathione peroxidase 4: a new player in neurodegeneration? Cardoso B R,Hare D J,Bush A I,Roberts B R Molecular psychiatry Glutathione peroxidase 4 (GPx4) is an antioxidant enzyme reported as an inhibitor of ferroptosis, a recently discovered non-apoptotic form of cell death. This pathway was initially described in cancer cells and has since been identified in hippocampal and renal cells. In this Perspective, we propose that inhibition of ferroptosis by GPx4 provides protective mechanisms against neurodegeneration. In addition, we suggest that selenium deficiency enhances susceptibility to ferroptotic processes, as well as other programmed cell death pathways due to a reduction in GPx4 activity. We review recent studies of GPx4 with an emphasis on neuronal protection, and discuss the relevance of selenium levels on its enzymatic activity. 10.1038/mp.2016.196
    A Mitochondrial-Targeted Nitroxide Is a Potent Inhibitor of Ferroptosis. Krainz Tanja,Gaschler Michael M,Lim Chaemin,Sacher Joshua R,Stockwell Brent R,Wipf Peter ACS central science Discovering compounds and mechanisms for inhibiting ferroptosis, a form of regulated, nonapoptotic cell death, has been of great interest in recent years. In this study, we demonstrate the ability of XJB-5-131, JP4-039, and other nitroxide-based lipid peroxidation mitigators to prevent ferroptotic cell death in HT-1080, BJeLR, and panc-1 cells. Several analogues of the reactive oxygen species (ROS) scavengers XJB-5-131 and JP4-039 were synthesized to probe structure-activity relationships and the influence of subcellular localization on the potency of these novel ferroptosis suppressors. Their biological activity correlated well over several orders of magnitude with their structure, relative lipophilicity, and respective enrichment in mitochondria, revealing a critical role of intramitochondrial lipid peroxidation in ferroptosis. These results also suggest that preventing mitochondrial lipid oxidation might offer a viable therapeutic opportunity in ischemia/reperfusion-induced tissue injury, acute kidney injury, and other pathologies that involve ferroptotic cell death pathways. 10.1021/acscentsci.6b00199
    Selenium Utilization by GPX4 Is Required to Prevent Hydroperoxide-Induced Ferroptosis. Ingold Irina,Berndt Carsten,Schmitt Sabine,Doll Sebastian,Poschmann Gereon,Buday Katalin,Roveri Antonella,Peng Xiaoxiao,Porto Freitas Florencio,Seibt Tobias,Mehr Lisa,Aichler Michaela,Walch Axel,Lamp Daniel,Jastroch Martin,Miyamoto Sayuri,Wurst Wolfgang,Ursini Fulvio,Arnér Elias S J,Fradejas-Villar Noelia,Schweizer Ulrich,Zischka Hans,Friedmann Angeli José Pedro,Conrad Marcus Cell Selenoproteins are rare proteins among all kingdoms of life containing the 21 amino acid, selenocysteine. Selenocysteine resembles cysteine, differing only by the substitution of selenium for sulfur. Yet the actual advantage of selenolate- versus thiolate-based catalysis has remained enigmatic, as most of the known selenoproteins also exist as cysteine-containing homologs. Here, we demonstrate that selenolate-based catalysis of the essential mammalian selenoprotein GPX4 is unexpectedly dispensable for normal embryogenesis. Yet the survival of a specific type of interneurons emerges to exclusively depend on selenocysteine-containing GPX4, thereby preventing fatal epileptic seizures. Mechanistically, selenocysteine utilization by GPX4 confers exquisite resistance to irreversible overoxidation as cells expressing a cysteine variant are highly sensitive toward peroxide-induced ferroptosis. Remarkably, concomitant deletion of all selenoproteins in Gpx4 cells revealed that selenoproteins are dispensable for cell viability provided partial GPX4 activity is retained. Conclusively, 200 years after its discovery, a specific and indispensable role for selenium is provided. 10.1016/j.cell.2017.11.048
    Resolving the Role of Lipoxygenases in the Initiation and Execution of Ferroptosis. Shah Ron,Shchepinov Mikhail S,Pratt Derek A ACS central science Lipoxygenases (LOXs) have been implicated as central players in ferroptosis, a recently characterized cell death modality associated with the accumulation of lipid hydroperoxides: the products of LOX catalysis. To provide insight on their role, human embryonic kidney cells were transfected to overexpress each of the human isoforms associated with disease, 5-LOX, p12-LOX, and 15-LOX-1, which yielded stable cell lines that were demonstrably sensitized to ferroptosis. Interestingly, the cells could be rescued by less than half of a diverse collection of known LOX inhibitors. Furthermore, the cytoprotective compounds were similarly potent in each of the cell lines even though some were clearly isoform-selective LOX inhibitors. The cytoprotective compounds were subsequently demonstrated to be effective radical-trapping antioxidants, which protect lipids from autoxidation, the autocatalytic radical chain reaction that produces lipid hydroperoxides. From these data (and others reported herein), a picture emerges wherein LOX activity contribute to the cellular pool of lipid hydroperoxides that initiate ferroptosis, but lipid autoxidation drives the cell death process. 10.1021/acscentsci.7b00589
    Role of Mitochondria in Ferroptosis. Gao Minghui,Yi Junmei,Zhu Jiajun,Minikes Alexander M,Monian Prashant,Thompson Craig B,Jiang Xuejun Molecular cell Ferroptosis is a regulated necrosis process driven by iron-dependent lipid peroxidation. Although ferroptosis and cellular metabolism interplay with one another, whether mitochondria are involved in ferroptosis is under debate. Here, we demonstrate that mitochondria play a crucial role in cysteine-deprivation-induced ferroptosis but not in that induced by inhibiting glutathione peroxidase-4 (GPX4), the most downstream component of the ferroptosis pathway. Mechanistically, cysteine deprivation leads to mitochondrial membrane potential hyperpolarization and lipid peroxide accumulation. Inhibition of mitochondrial TCA cycle or electron transfer chain (ETC) mitigated mitochondrial membrane potential hyperpolarization, lipid peroxide accumulation, and ferroptosis. Blockage of glutaminolysis had the same inhibitory effect, which was counteracted by supplying downstream TCA cycle intermediates. Importantly, loss of function of fumarate hydratase, a tumor suppressor and TCA cycle component, confers resistance to cysteine-deprivation-induced ferroptosis. Collectively, this work demonstrates the crucial role of mitochondria in cysteine-deprivation-induced ferroptosis and implicates ferroptosis in tumor suppression. 10.1016/j.molcel.2018.10.042
    A powerful cell-protection system prevents cell death by ferroptosis. Stockwell Brent R Nature 10.1038/d41586-019-03145-8
    Broken hearts: Iron overload, ferroptosis and cardiomyopathy. Conrad Marcus,Proneth Bettina Cell research 10.1038/s41422-019-0150-y
    Selenium Drives a Transcriptional Adaptive Program to Block Ferroptosis and Treat Stroke. Alim Ishraq,Caulfield Joseph T,Chen Yingxin,Swarup Vivek,Geschwind Daniel H,Ivanova Elena,Seravalli Javier,Ai Youxi,Sansing Lauren H,Ste Marie Emma J,Hondal Robert J,Mukherjee Sushmita,Cave John W,Sagdullaev Botir T,Karuppagounder Saravanan S,Ratan Rajiv R Cell Ferroptosis, a non-apoptotic form of programmed cell death, is triggered by oxidative stress in cancer, heat stress in plants, and hemorrhagic stroke. A homeostatic transcriptional response to ferroptotic stimuli is unknown. We show that neurons respond to ferroptotic stimuli by induction of selenoproteins, including antioxidant glutathione peroxidase 4 (GPX4). Pharmacological selenium (Se) augments GPX4 and other genes in this transcriptional program, the selenome, via coordinated activation of the transcription factors TFAP2c and Sp1 to protect neurons. Remarkably, a single dose of Se delivered into the brain drives antioxidant GPX4 expression, protects neurons, and improves behavior in a hemorrhagic stroke model. Altogether, we show that pharmacological Se supplementation effectively inhibits GPX4-dependent ferroptotic death as well as cell death induced by excitotoxicity or ER stress, which are GPX4 independent. Systemic administration of a brain-penetrant selenopeptide activates homeostatic transcription to inhibit cell death and improves function when delivered after hemorrhagic or ischemic stroke. 10.1016/j.cell.2019.03.032
    ACSL4 dictates ferroptosis sensitivity by shaping cellular lipid composition. Doll Sebastian,Proneth Bettina,Tyurina Yulia Y,Panzilius Elena,Kobayashi Sho,Ingold Irina,Irmler Martin,Beckers Johannes,Aichler Michaela,Walch Axel,Prokisch Holger,Trümbach Dietrich,Mao Gaowei,Qu Feng,Bayir Hulya,Füllekrug Joachim,Scheel Christina H,Wurst Wolfgang,Schick Joel A,Kagan Valerian E,Angeli José Pedro Friedmann,Conrad Marcus Nature chemical biology Ferroptosis is a form of regulated necrotic cell death controlled by glutathione peroxidase 4 (GPX4). At present, mechanisms that could predict sensitivity and/or resistance and that may be exploited to modulate ferroptosis are needed. We applied two independent approaches-a genome-wide CRISPR-based genetic screen and microarray analysis of ferroptosis-resistant cell lines-to uncover acyl-CoA synthetase long-chain family member 4 (ACSL4) as an essential component for ferroptosis execution. Specifically, Gpx4-Acsl4 double-knockout cells showed marked resistance to ferroptosis. Mechanistically, ACSL4 enriched cellular membranes with long polyunsaturated ω6 fatty acids. Moreover, ACSL4 was preferentially expressed in a panel of basal-like breast cancer cell lines and predicted their sensitivity to ferroptosis. Pharmacological targeting of ACSL4 with thiazolidinediones, a class of antidiabetic compound, ameliorated tissue demise in a mouse model of ferroptosis, suggesting that ACSL4 inhibition is a viable therapeutic approach to preventing ferroptosis-related diseases. 10.1038/nchembio.2239
    The CoQ oxidoreductase FSP1 acts parallel to GPX4 to inhibit ferroptosis. Bersuker Kirill,Hendricks Joseph M,Li Zhipeng,Magtanong Leslie,Ford Breanna,Tang Peter H,Roberts Melissa A,Tong Bingqi,Maimone Thomas J,Zoncu Roberto,Bassik Michael C,Nomura Daniel K,Dixon Scott J,Olzmann James A Nature Ferroptosis is a form of regulated cell death that is caused by the iron-dependent peroxidation of lipids. The glutathione-dependent lipid hydroperoxidase glutathione peroxidase 4 (GPX4) prevents ferroptosis by converting lipid hydroperoxides into non-toxic lipid alcohols. Ferroptosis has previously been implicated in the cell death that underlies several degenerative conditions, and induction of ferroptosis by the inhibition of GPX4 has emerged as a therapeutic strategy to trigger cancer cell death. However, sensitivity to GPX4 inhibitors varies greatly across cancer cell lines, which suggests that additional factors govern resistance to ferroptosis. Here, using a synthetic lethal CRISPR-Cas9 screen, we identify ferroptosis suppressor protein 1 (FSP1) (previously known as apoptosis-inducing factor mitochondrial 2 (AIFM2)) as a potent ferroptosis-resistance factor. Our data indicate that myristoylation recruits FSP1 to the plasma membrane where it functions as an oxidoreductase that reduces coenzyme Q (CoQ) (also known as ubiquinone-10), which acts as a lipophilic radical-trapping antioxidant that halts the propagation of lipid peroxides. We further find that FSP1 expression positively correlates with ferroptosis resistance across hundreds of cancer cell lines, and that FSP1 mediates resistance to ferroptosis in lung cancer cells in culture and in mouse tumour xenografts. Thus, our data identify FSP1 as a key component of a non-mitochondrial CoQ antioxidant system that acts in parallel to the canonical glutathione-based GPX4 pathway. These findings define a ferroptosis suppression pathway and indicate that pharmacological inhibition of FSP1 may provide an effective strategy to sensitize cancer cells to ferroptosis-inducing chemotherapeutic agents. 10.1038/s41586-019-1705-2
    FSP1 is a glutathione-independent ferroptosis suppressor. Doll Sebastian,Freitas Florencio Porto,Shah Ron,Aldrovandi Maceler,da Silva Milene Costa,Ingold Irina,Goya Grocin Andrea,Xavier da Silva Thamara Nishida,Panzilius Elena,Scheel Christina H,Mourão André,Buday Katalin,Sato Mami,Wanninger Jonas,Vignane Thibaut,Mohana Vaishnavi,Rehberg Markus,Flatley Andrew,Schepers Aloys,Kurz Andreas,White Daniel,Sauer Markus,Sattler Michael,Tate Edward William,Schmitz Werner,Schulze Almut,O'Donnell Valerie,Proneth Bettina,Popowicz Grzegorz M,Pratt Derek A,Angeli José Pedro Friedmann,Conrad Marcus Nature Ferroptosis is an iron-dependent form of necrotic cell death marked by oxidative damage to phospholipids. To date, ferroptosis has been thought to be controlled only by the phospholipid hydroperoxide-reducing enzyme glutathione peroxidase 4 (GPX4) and radical-trapping antioxidants. However, elucidation of the factors that underlie the sensitivity of a given cell type to ferroptosis is crucial to understand the pathophysiological role of ferroptosis and how it may be exploited for the treatment of cancer. Although metabolic constraints and phospholipid composition contribute to ferroptosis sensitivity, no cell-autonomous mechanisms have been identified that account for the resistance of cells to ferroptosis. Here we used an expression cloning approach to identify genes in human cancer cells that are able to complement the loss of GPX4. We found that the flavoprotein apoptosis-inducing factor mitochondria-associated 2 (AIFM2) is a previously unrecognized anti-ferroptotic gene. AIFM2, which we renamed ferroptosis suppressor protein 1 (FSP1) and which was initially described as a pro-apoptotic gene, confers protection against ferroptosis elicited by GPX4 deletion. We further demonstrate that the suppression of ferroptosis by FSP1 is mediated by ubiquinone (also known as coenzyme Q, CoQ): the reduced form, ubiquinol, traps lipid peroxyl radicals that mediate lipid peroxidation, whereas FSP1 catalyses the regeneration of CoQ using NAD(P)H. Pharmacological targeting of FSP1 strongly synergizes with GPX4 inhibitors to trigger ferroptosis in a number of cancer entities. In conclusion, the FSP1-CoQ-NAD(P)H pathway exists as a stand-alone parallel system, which co-operates with GPX4 and glutathione to suppress phospholipid peroxidation and ferroptosis. 10.1038/s41586-019-1707-0
    Ferroptosis: Yet Another Way to Die. Kazan Kemal,Kalaipandian Sundaravelpandian Trends in plant science Cell death is one of the most fundamental biological processes operating in multicellular organisms. Recent research highlighted here [Distéfano et al. (J. Cell Biol. 2017:216;463-476) and Dangol et al. (Plant Cell 2019:31;189-209)] revealed an iron- and ROS-dependent cell death phenomenon called ferroptosis in plants. Features distinguishing ferroptosis from other cell death events and how ferroptosis can be exploited to improve plant performance are discussed. 10.1016/j.tplants.2019.03.005
    Glutaminolysis and Transferrin Regulate Ferroptosis. Gao Minghui,Monian Prashant,Quadri Nosirudeen,Ramasamy Ravichandran,Jiang Xuejun Molecular cell Ferroptosis has emerged as a new form of regulated necrosis that is implicated in various human diseases. However, the mechanisms of ferroptosis are not well defined. This study reports the discovery of multiple molecular components of ferroptosis and its intimate interplay with cellular metabolism and redox machinery. Nutrient starvation often leads to sporadic apoptosis. Strikingly, we found that upon deprivation of amino acids, a more rapid and potent necrosis process can be induced in a serum-dependent manner, which was subsequently determined to be ferroptosis. Two serum factors, the iron-carrier protein transferrin and amino acid glutamine, were identified as the inducers of ferroptosis. We further found that the cell surface transferrin receptor and the glutamine-fueled intracellular metabolic pathway, glutaminolysis, played crucial roles in the death process. Inhibition of glutaminolysis, the essential component of ferroptosis, can reduce heart injury triggered by ischemia/reperfusion, suggesting a potential therapeutic approach for treating related diseases. 10.1016/j.molcel.2015.06.011
    Involvement of cigarette smoke-induced epithelial cell ferroptosis in COPD pathogenesis. Yoshida Masahiro,Minagawa Shunsuke,Araya Jun,Sakamoto Taro,Hara Hiromichi,Tsubouchi Kazuya,Hosaka Yusuke,Ichikawa Akihiro,Saito Nayuta,Kadota Tsukasa,Sato Nahoko,Kurita Yusuke,Kobayashi Kenji,Ito Saburo,Utsumi Hirohumi,Wakui Hiroshi,Numata Takanori,Kaneko Yumi,Mori Shohei,Asano Hisatoshi,Yamashita Makoto,Odaka Makoto,Morikawa Toshiaki,Nakayama Katsutoshi,Iwamoto Takeo,Imai Hirotaka,Kuwano Kazuyoshi Nature communications Ferroptosis is a necrotic form of regulated cell death (RCD) mediated by phospholipid peroxidation in association with free iron-mediated Fenton reactions. Disrupted iron homeostasis resulting in excessive oxidative stress has been implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). Here, we demonstrate the involvement of ferroptosis in COPD pathogenesis. Our in vivo and in vitro models show labile iron accumulation and enhanced lipid peroxidation with concomitant non-apoptotic cell death during cigarette smoke (CS) exposure, which are negatively regulated by GPx4 activity. Treatment with deferoxamine and ferrostatin-1, in addition to GPx4 knockdown, illuminate the role of ferroptosis in CS-treated lung epithelial cells. NCOA4-mediated ferritin selective autophagy (ferritinophagy) is initiated during ferritin degradation in response to CS treatment. CS exposure models, using both GPx4-deficient and overexpressing mice, clarify the pivotal role of GPx4-regulated cell death during COPD. These findings support a role for cigarette smoke-induced ferroptosis in the pathogenesis of COPD. 10.1038/s41467-019-10991-7
    On the Mechanism of Cytoprotection by Ferrostatin-1 and Liproxstatin-1 and the Role of Lipid Peroxidation in Ferroptotic Cell Death. Zilka Omkar,Shah Ron,Li Bo,Friedmann Angeli José Pedro,Griesser Markus,Conrad Marcus,Pratt Derek A ACS central science Ferroptosis is a form of regulated necrosis associated with the iron-dependent accumulation of lipid hydroperoxides that may play a key role in the pathogenesis of degenerative diseases in which lipid peroxidation has been implicated. High-throughput screening efforts have identified ferrostatin-1 (Fer-1) and liproxstatin-1 (Lip-1) as potent inhibitors of ferroptosis - an activity that has been ascribed to their ability to slow the accumulation of lipid hydroperoxides. Herein we demonstrate that this activity likely derives from their reactivity as radical-trapping antioxidants (RTAs) rather than their potency as inhibitors of lipoxygenases. Although inhibited autoxidations of styrene revealed that Fer-1 and Lip-1 react roughly 10-fold more slowly with peroxyl radicals than reactions of α-tocopherol (α-TOH), they were significantly more reactive than α-TOH in phosphatidylcholine lipid bilayers - consistent with the greater potency of Fer-1 and Lip-1 relative to α-TOH as inhibitors of ferroptosis. None of Fer-1, Lip-1, and α-TOH inhibited human 15-lipoxygenase-1 (15-LOX-1) overexpressed in HEK-293 cells when assayed at concentrations where they inhibited ferroptosis. These results stand in stark contrast to those obtained with a known 15-LOX-1 inhibitor (PD146176), which was able to inhibit the enzyme at concentrations where it was effective in inhibiting ferroptosis. Given the likelihood that Fer-1 and Lip-1 subvert ferroptosis by inhibiting lipid peroxidation as RTAs, we evaluated the antiferroptotic potential of 1,8-tetrahydronaphthyridinols (hereafter THNs): rationally designed radical-trapping antioxidants of unparalleled reactivity. We show for the first time that the inherent reactivity of the THNs translates to cell culture, where lipophilic THNs were similarly effective to Fer-1 and Lip-1 at subverting ferroptosis induced by either pharmacological or genetic inhibition of the hydroperoxide-detoxifying enzyme Gpx4 in mouse fibroblasts, and glutamate-induced death of mouse hippocampal cells. These results demonstrate that potent RTAs subvert ferroptosis and suggest that lipid peroxidation (autoxidation) may play a central role in the process. 10.1021/acscentsci.7b00028
    Metal Ions in Alzheimer's Disease: A Key Role or Not? Liu Yan,Nguyen Michel,Robert Anne,Meunier Bernard Accounts of chemical research Despite tremendous research efforts in universities and pharmaceutical companies, effective drugs are still lacking for the treatment of Alzheimer's disease (AD). The biochemical mechanisms of this devastating neurodegenerative disease have not yet been clearly understood. Besides a small percentage of cases with early onset disease having a genetic origin (<5%, familial AD), most cases develop in the elderly as a sporadic form due to multiple and complex parameters of aging. Consequently, AD is spreading in all countries with a long life expectancy. AD is characterized by deposition of senile plaques made of β-amyloid proteins (Aβ) and by hyperphosphorylation of tau proteins, which have been considered as the main drug targets up to now. However, antibodies targeting amyloid aggregates, as well as enzyme inhibitors aiming to modify the amyloid precursor protein processing, have failed to improve cognition in clinical trials. Thus, to set up effective drugs, it is urgent to enlarge the panel of drug targets. Evidence of the link between AD and redox metal dysregulation has also been supported by post-mortem analyses of amyloid plaques, which revealed accumulation of copper, iron, and zinc by 5.7, 2.8, and 3.1 times, respectively, the levels observed in normal brains. Copper-amyloid complexes, in the presence of endogenous reductants, are able to catalyze the reduction of dioxygen and to produce reduced, reactive oxygen species (ROS), leading to neuron death. The possibility of using metal chelators to regenerate normal trafficking of metal ions has been considered as a promising strategy in order to reduce the redox stress lethal for neurons. However, most attempts to use metal chelators as therapeutic agents have been limited to existing molecules available from the shelves. Very few chelators have resulted from a rational design aiming to create drugs with a safety profile and able to cross the blood-brain barrier after an oral administration. In the human body, metals are handled by a sophisticated protein network to strictly control their transport and reactivity. Abnormal concentrations of certain metals may lead to pathological events due to misaccumulation and irregular reactivity. Consequently, therapeutic attempts to restore metal homeostasis should carefully take into account the coordination chemistry specificities of the concerned redox-active metal ions. This Account is focused on the role of the main biologically redox-active transition metals, iron and copper. For iron, the recent debate on the possible role of magnetite in AD pathogenesis is presented. The section devoted to copper is focused on the design of specific copper chelators as drug candidates able to regulate copper homeostasis and to reduce the oxidative damage responsible for the neuron death observed in AD brains. A short survey on non-redox-active metal ions is also included at the beginning, such as aluminum and its controversial role in AD and zinc which is a key metal ion in the brain. 10.1021/acs.accounts.9b00248
    Activation of the p62-Keap1-NRF2 pathway protects against ferroptosis in hepatocellular carcinoma cells. Sun Xiaofang,Ou Zhanhui,Chen Ruochan,Niu Xiaohua,Chen De,Kang Rui,Tang Daolin Hepatology (Baltimore, Md.) UNLABELLED:Ferroptosis is a recently recognized form of regulated cell death caused by an iron-dependent accumulation of lipid reactive oxygen species. However, the molecular mechanisms regulating ferroptosis remain obscure. Here, we report that nuclear factor erythroid 2-related factor 2 (NRF2) plays a central role in protecting hepatocellular carcinoma (HCC) cells against ferroptosis. Upon exposure to ferroptosis-inducing compounds (e.g., erastin, sorafenib, and buthionine sulfoximine), p62 expression prevented NRF2 degradation and enhanced subsequent NRF2 nuclear accumulation through inactivation of Kelch-like ECH-associated protein 1. Additionally, nuclear NRF2 interacted with transcriptional coactivator small v-maf avian musculoaponeurotic fibrosarcoma oncogene homolog proteins such as MafG and then activated transcription of quinone oxidoreductase-1, heme oxygenase-1, and ferritin heavy chain-1. Knockdown of p62, quinone oxidoreductase-1, heme oxygenase-1, and ferritin heavy chain-1 by RNA interference in HCC cells promoted ferroptosis in response to erastin and sorafenib. Furthermore, genetic or pharmacologic inhibition of NRF2 expression/activity in HCC cells increased the anticancer activity of erastin and sorafenib in vitro and in tumor xenograft models. CONCLUSION:These findings demonstrate novel molecular mechanisms and signaling pathways of ferroptosis; the status of NRF2 is a key factor that determines the therapeutic response to ferroptosis-targeted therapies in HCC cells. 10.1002/hep.28251
    Death by iron. Dempsey Laurie A Nature immunology 10.1038/s41590-019-0411-4
    Brain iron is associated with accelerated cognitive decline in people with Alzheimer pathology. Ayton Scott,Wang Yamin,Diouf Ibrahima,Schneider Julie A,Brockman John,Morris Martha Clare,Bush Ashley I Molecular psychiatry Cortical iron has been shown to be elevated in Alzheimer's disease (AD), but the impact of the directly measured iron on the clinical syndrome has not been assessed. We investigated the association between post-mortem iron levels with the clinical and pathological diagnosis of AD, its severity, and the rate of cognitive decline in the 12 years prior to death in subjects from the Memory and Aging Project (n = 209). Iron was elevated (β [SE] = 9.7 [2.6]; P = 3.0 × 10) in the inferior temporal cortex only in subjects who were diagnosed with clinical AD during life and had a diagnosis of AD confirmed post-mortem by standardized criteria. Although iron was weakly associated with the extent of proteinopathy in tissue with AD neuropathology, it was strongly associated with the rate of cognitive decline (e.g., global cognition: β [SE] = -0.040 [0.005], P = 1.6 × 10). Thus, cortical iron might act to propel cognitive deterioration upon the underlying proteinopathy of AD, possibly by inducing oxidative stress or ferroptotic cell death, or may be related to an inflammatory response. 10.1038/s41380-019-0375-7
    Transcription factor NRF2 protects mice against dietary iron-induced liver injury by preventing hepatocytic cell death. Silva-Gomes Sandro,Santos Ana G,Caldas Carolina,Silva Cátia M,Neves João V,Lopes Joanne,Carneiro Fátima,Rodrigues Pedro N,Duarte Tiago L Journal of hepatology BACKGROUND & AIMS:The liver, being the major site of iron storage, is particularly exposed to the toxic effects of iron. Transcription factor NRF2 is critical for protecting the liver against disease by activating the transcription of genes encoding detoxification/antioxidant enzymes. We aimed to determine if the NRF2 pathway plays a significant role in the protection against hepatic iron overload. METHODS:Wild-type and Nrf2(-/-) mouse primary hepatocytes were incubated with ferric ammonium citrate. Wild-type and Nrf2(-/-) mice were fed standard rodent chow or iron-rich diet for 2weeks, with or without daily injection of the antioxidant mito-TEMPOL. RESULTS:In mouse hepatocytes, iron induced the nuclear translocation of NRF2 and the expression of cytoprotective genes in an NRF2-dependent manner. Moreover, Nrf2(-/-) hepatocytes were highly susceptible to iron-induced cell death. Wild-type and Nrf2(-/-) mice fed iron-rich diet accumulated similar amounts of iron in the liver and were equally able to increase the expression of hepatic hepcidin and ferritin. Nevertheless, in Nrf2-null mice the iron loading resulted in progressive liver injury, ranging from mild confluent necrosis to severe necroinflammatory lesions. Hepatocytic cell death was associated with gross ultrastructural damage to the mitochondria. Notably, liver injury was prevented in iron-fed animals that received mito-TEMPOL. CONCLUSIONS:NRF2 protects the mouse liver against the toxicity of dietary iron overload by preventing hepatocytic cell death. We identify NRF2 as a potential modifier of liver disease in iron overload pathology and show the beneficial effect of the antioxidant mito-TEMPOL in a mouse model of dietary iron-induced liver injury. 10.1016/j.jhep.2013.09.004
    Ferroptosis is an autophagic cell death process. Gao Minghui,Monian Prashant,Pan Qiuhui,Zhang Wei,Xiang Jenny,Jiang Xuejun Cell research Ferroptosis is an iron-dependent form of regulated necrosis. It is implicated in various human diseases, including ischemic organ damage and cancer. Here, we report the crucial role of autophagy, particularly autophagic degradation of cellular iron storage proteins (a process known as ferritinophagy), in ferroptosis. Using RNAi screening coupled with subsequent genetic analysis, we identified multiple autophagy-related genes as positive regulators of ferroptosis. Ferroptosis induction led to autophagy activation and consequent degradation of ferritin and ferritinophagy cargo receptor NCOA4. Consistently, inhibition of ferritinophagy by blockage of autophagy or knockdown of NCOA4 abrogated the accumulation of ferroptosis-associated cellular labile iron and reactive oxygen species, as well as eventual ferroptotic cell death. Therefore, ferroptosis is an autophagic cell death process, and NCOA4-mediated ferritinophagy supports ferroptosis by controlling cellular iron homeostasis. 10.1038/cr.2016.95
    Ferroptosis: A Regulated Cell Death Nexus Linking Metabolism, Redox Biology, and Disease. Stockwell Brent R,Friedmann Angeli José Pedro,Bayir Hülya,Bush Ashley I,Conrad Marcus,Dixon Scott J,Fulda Simone,Gascón Sergio,Hatzios Stavroula K,Kagan Valerian E,Noel Kay,Jiang Xuejun,Linkermann Andreas,Murphy Maureen E,Overholtzer Michael,Oyagi Atsushi,Pagnussat Gabriela C,Park Jason,Ran Qitao,Rosenfeld Craig S,Salnikow Konstantin,Tang Daolin,Torti Frank M,Torti Suzy V,Toyokuni Shinya,Woerpel K A,Zhang Donna D Cell Ferroptosis is a form of regulated cell death characterized by the iron-dependent accumulation of lipid hydroperoxides to lethal levels. Emerging evidence suggests that ferroptosis represents an ancient vulnerability caused by the incorporation of polyunsaturated fatty acids into cellular membranes, and cells have developed complex systems that exploit and defend against this vulnerability in different contexts. The sensitivity to ferroptosis is tightly linked to numerous biological processes, including amino acid, iron, and polyunsaturated fatty acid metabolism, and the biosynthesis of glutathione, phospholipids, NADPH, and coenzyme Q. Ferroptosis has been implicated in the pathological cell death associated with degenerative diseases (i.e., Alzheimer's, Huntington's, and Parkinson's diseases), carcinogenesis, stroke, intracerebral hemorrhage, traumatic brain injury, ischemia-reperfusion injury, and kidney degeneration in mammals and is also implicated in heat stress in plants. Ferroptosis may also have a tumor-suppressor function that could be harnessed for cancer therapy. This Primer reviews the mechanisms underlying ferroptosis, highlights connections to other areas of biology and medicine, and recommends tools and guidelines for studying this emerging form of regulated cell death. 10.1016/j.cell.2017.09.021
    Iron and dopamine: a toxic couple. Hare Dominic J,Double Kay L Brain : a journal of neurology Iron accumulation is a cardinal feature of degenerating regions in the Parkinson's disease brain. As a potent pro-oxidant, redox-active iron may be a key player in upstream mechanisms that precipitate cell death in this disorder. Although an elevation in brain iron levels is a normal feature of ageing, the increase is greater in Parkinson's disease; on the other hand, the effects of the disease are most marked in the nigrostriatal dopaminergic system. In this Update, we explain that neurodegeneration in the affected regions may result from the potent redox couple formed by iron and dopamine itself, and discuss the clinical implications of this molecular trait in this dynamic and rapidly moving area of Parkinson's disease research. 10.1093/brain/aww022
    FINO initiates ferroptosis through GPX4 inactivation and iron oxidation. Gaschler Michael M,Andia Alexander A,Liu Hengrui,Csuka Joleen M,Hurlocker Brisa,Vaiana Christopher A,Heindel Daniel W,Zuckerman Dylan S,Bos Pieter H,Reznik Eduard,Ye Ling F,Tyurina Yulia Y,Lin Annie J,Shchepinov Mikhail S,Chan Amy Y,Peguero-Pereira Eveliz,Fomich Maksim A,Daniels Jacob D,Bekish Andrei V,Shmanai Vadim V,Kagan Valerian E,Mahal Lara K,Woerpel K A,Stockwell Brent R Nature chemical biology Ferroptosis is a non-apoptotic form of regulated cell death caused by the failure of the glutathione-dependent lipid-peroxide-scavenging network. FINO is an endoperoxide-containing 1,2-dioxolane that can initiate ferroptosis selectively in engineered cancer cells. We investigated the mechanism and structural features necessary for ferroptosis initiation by FINO. We found that FINO requires both an endoperoxide moiety and a nearby hydroxyl head group to initiate ferroptosis. In contrast to previously described ferroptosis inducers, FINO does not inhibit system x or directly target the reducing enzyme GPX4, as do erastin and RSL3, respectively, nor does it deplete GPX4 protein, as does FIN56. Instead, FINO both indirectly inhibits GPX4 enzymatic function and directly oxidizes iron, ultimately causing widespread lipid peroxidation. These findings suggest that endoperoxides such as FINO can initiate a multipronged mechanism of ferroptosis. 10.1038/s41589-018-0031-6
    Ferroptosis: Death by Lipid Peroxidation. Yang Wan Seok,Stockwell Brent R Trends in cell biology Ferroptosis is a regulated form of cell death driven by loss of activity of the lipid repair enzyme glutathione peroxidase 4 (GPX4) and subsequent accumulation of lipid-based reactive oxygen species (ROS), particularly lipid hydroperoxides. This form of iron-dependent cell death is genetically, biochemically, and morphologically distinct from other cell death modalities, including apoptosis, unregulated necrosis, and necroptosis. Ferroptosis is regulated by specific pathways and is involved in diverse biological contexts. Here we summarize the discovery of ferroptosis, the mechanism of ferroptosis regulation, and its increasingly appreciated relevance to both normal and pathological physiology. 10.1016/j.tcb.2015.10.014
    Blood-derived iron mediates free radical production and neuronal death in the hippocampal CA1 area following transient forebrain ischemia in rat. Park Ui Jin,Lee Young Ae,Won Sun Mi,Lee Jin Hwan,Kang Seung-Hee,Springer Joe E,Lee Yong Beom,Gwag Byoung Joo Acta neuropathologica Abnormal brain iron homeostasis has been proposed as a pathological event leading to oxidative stress and neuronal injury under pathological conditions. We examined the possibility that neuronal iron overload would mediate free radical production and delayed neuronal death (DND) in hippocampal CA1 area after transient forebrain ischemia (TFI). Mitochondrial free radicals (MFR) were biphasically generated in CA1 neurons 0.5-8 and 48-60 h after TFI. Treatment with Neu2000, a potent spin trapping molecule, as well as trolox, a vitamin E analogue, blocked the biphasic MFR production and attenuated DND in the CA1, regardless of whether it was administered immediately or even 24 h after reperfusion. The late increase in MFR was accompanied by iron accumulation and blocked by the administration of deferoxamine-an iron chelator. Iron accumulation was attributable to prolonged upregulation of the transferrin receptor and to increased uptake of peripheral iron through a leaky blood-brain barrier. Infiltration of iron-containing cells and iron accumulation were attenuated by depletion of circulating blood cells through X-ray irradiation of the whole body except the head. The present findings suggest that excessive iron transported from blood mediates slowly evolving oxidative stress and neuronal death in CA1 after TFI, and that targeting iron-mediated oxidative stress holds extended therapeutic time window against an ischemic event. 10.1007/s00401-010-0785-8
    Ferroptosis: an iron-dependent form of nonapoptotic cell death. Dixon Scott J,Lemberg Kathryn M,Lamprecht Michael R,Skouta Rachid,Zaitsev Eleina M,Gleason Caroline E,Patel Darpan N,Bauer Andras J,Cantley Alexandra M,Yang Wan Seok,Morrison Barclay,Stockwell Brent R Cell Nonapoptotic forms of cell death may facilitate the selective elimination of some tumor cells or be activated in specific pathological states. The oncogenic RAS-selective lethal small molecule erastin triggers a unique iron-dependent form of nonapoptotic cell death that we term ferroptosis. Ferroptosis is dependent upon intracellular iron, but not other metals, and is morphologically, biochemically, and genetically distinct from apoptosis, necrosis, and autophagy. We identify the small molecule ferrostatin-1 as a potent inhibitor of ferroptosis in cancer cells and glutamate-induced cell death in organotypic rat brain slices, suggesting similarities between these two processes. Indeed, erastin, like glutamate, inhibits cystine uptake by the cystine/glutamate antiporter (system x(c)(-)), creating a void in the antioxidant defenses of the cell and ultimately leading to iron-dependent, oxidative death. Thus, activation of ferroptosis results in the nonapoptotic destruction of certain cancer cells, whereas inhibition of this process may protect organisms from neurodegeneration. 10.1016/j.cell.2012.03.042
    Mitochondrial Iron in Human Health and Disease. Ward Diane M,Cloonan Suzanne M Annual review of physiology Mitochondria are an iconic distinguishing feature of eukaryotic cells. Mitochondria encompass an active organellar network that fuses, divides, and directs a myriad of vital biological functions, including energy metabolism, cell death regulation, and innate immune signaling in different tissues. Another crucial and often underappreciated function of these dynamic organelles is their central role in the metabolism of the most abundant and biologically versatile transition metals in mammalian cells, iron. In recent years, cellular and animal models of mitochondrial iron dysfunction have provided vital information in identifying new proteins that have elucidated the pathways involved in mitochondrial homeostasis and iron metabolism. Specific signatures of mitochondrial iron dysregulation that are associated with disease pathogenesis and/or progression are becoming increasingly important. Understanding the molecular mechanisms regulating mitochondrial iron pathways will help better define the role of this important metal in mitochondrial function and in human health and disease. 10.1146/annurev-physiol-020518-114742
    Tom20 senses iron-activated ROS signaling to promote melanoma cell pyroptosis. Zhou Bo,Zhang Jia-Yuan,Liu Xian-Shuo,Chen Hang-Zi,Ai Yuan-Li,Cheng Kang,Sun Ru-Yue,Zhou Dawang,Han Jiahuai,Wu Qiao Cell research Iron has been shown to trigger oxidative stress by elevating reactive oxygen species (ROS) and to participate in different modes of cell death, such as ferroptosis, apoptosis and necroptosis. However, whether iron-elevated ROS is also linked to pyroptosis has not been reported. Here, we demonstrate that iron-activated ROS can induce pyroptosis via a Tom20-Bax-caspase-GSDME pathway. In melanoma cells, iron enhanced ROS signaling initiated by CCCP, causing the oxidation and oligomerization of the mitochondrial outer membrane protein Tom20. Bax is recruited to mitochondria by oxidized Tom20, which facilitates cytochrome c release to cytosol to activate caspase-3, eventually triggering pyroptotic death by inducing GSDME cleavage. Therefore, ROS acts as a causative factor and Tom20 senses ROS signaling for iron-driven pyroptotic death of melanoma cells. Since iron activates ROS for GSDME-dependent pyroptosis induction and melanoma cells specifically express a high level of GSDME, iron may be a potential candidate for melanoma therapy. Based on the functional mechanism of iron shown above, we further demonstrate that iron supplementation at a dosage used in iron-deficient patients is sufficient to maximize the anti-tumor effect of clinical ROS-inducing drugs to inhibit xenograft tumor growth and metastasis of melanoma cells through GSDME-dependent pyroptosis. Moreover, no obvious side effects are observed in the normal tissues and organs of mice during the combined treatment of clinical drugs and iron. This study not only identifies iron as a sensitizer amplifying ROS signaling to drive pyroptosis, but also implicates a novel iron-based intervention strategy for melanoma therapy. 10.1038/s41422-018-0090-y
    The role of iron and reactive oxygen species in cell death. Dixon Scott J,Stockwell Brent R Nature chemical biology The transition metal iron is essential for life, yet potentially toxic iron-catalyzed reactive oxygen species (ROS) are unavoidable in an oxygen-rich environment. Iron and ROS are increasingly recognized as important initiators and mediators of cell death in a variety of organisms and pathological situations. Here, we review recent discoveries regarding the mechanism by which iron and ROS participate in cell death. We describe the different roles of iron in triggering cell death, targets of iron-dependent ROS that mediate cell death and a new form of iron-dependent cell death termed ferroptosis. Recent advances in understanding the role of iron and ROS in cell death offer unexpected surprises and suggest new therapeutic avenues to treat cancer, organ damage and degenerative disease. 10.1038/nchembio.1416
    Regulators of Iron Homeostasis: New Players in Metabolism, Cell Death, and Disease. Bogdan Alexander R,Miyazawa Masaki,Hashimoto Kazunori,Tsuji Yoshiaki Trends in biochemical sciences Iron is necessary for life, but can also cause cell death. Accordingly, cells evolved a robust, tightly regulated suite of genes for maintaining iron homeostasis. Previous mechanistic studies on iron homeostasis have granted insight into the role of iron in human health and disease. We highlight new regulators of iron metabolism, including iron-trafficking proteins [solute carrier family 39, SLC39, also known as ZRT/IRT-like protein, ZIP; and poly-(rC)-binding protein, PCBP] and a cargo receptor (NCOA4) that is crucial for release of ferritin-bound iron. We also discuss emerging roles of iron in apoptosis and a novel iron-dependent cell death pathway termed 'ferroptosis', the dysregulation of iron metabolism in human pathologies, and the use of iron chelators in cancer therapy. 10.1016/j.tibs.2015.11.012
    Cell-Line Selectivity Improves the Predictive Power of Pharmacogenomic Analyses and Helps Identify NADPH as Biomarker for Ferroptosis Sensitivity. Shimada Kenichi,Hayano Miki,Pagano Nen C,Stockwell Brent R Cell chemical biology Precision medicine in oncology requires not only identification of cancer-associated mutations but also effective drugs for each cancer genotype, which is still a largely unsolved problem. One approach for the latter challenge has been large-scale testing of small molecules in genetically characterized cell lines. We hypothesized that compounds with high cell-line-selective lethality exhibited consistent results across such pharmacogenomic studies. We analyzed the compound sensitivity data of 6,259 lethal compounds from the NCI-60 project. A total of 2,565 cell-line-selective lethal compounds were identified and grouped into 18 clusters based on their median growth inhibitory GI50 profiles across the 60 cell lines, which were shown to represent distinct mechanisms of action. Further transcriptome analysis revealed a biomarker, NADPH abundance, for predicting sensitivity to ferroptosis-inducing compounds, which we experimentally validated. In summary, incorporating cell-line-selectivity filters improves the predictive power of pharmacogenomic analyses and enables discovery of biomarkers that predict the sensitivity of cells to specific cell death inducers. 10.1016/j.chembiol.2015.11.016
    The Molecular Mechanisms of Regulating Oxidative Stress-Induced Ferroptosis and Therapeutic Strategy in Tumors. Zhu Jinghan,Xiong Yixiao,Zhang Yuxin,Wen Jingyuan,Cai Ning,Cheng Kun,Liang Huifang,Zhang Wanguang Oxidative medicine and cellular longevity Ferroptosis is an atypical form of regulated cell death, which is different from apoptosis, necrosis, pyroptosis, and autophagy. Ferroptosis is characterized by iron-dependent oxidative destruction of cellular membranes following the antioxidant system's failure. The sensitivity of ferroptosis is tightly regulated by a series of biological processes, the metabolism of iron, amino acids, and polyunsaturated fatty acids, and the interaction of glutathione (GSH), NADPH, coenzyme Q10 (CoQ10), and phospholipids. Elevated oxidative stress (ROS) level is a hallmark of cancer, and ferroptosis serves as a link between nutrition metabolism and redox biology. Targeting ferroptosis may be an effective and selective way for cancer therapy. The underlying molecular mechanism of ferroptosis occurrence is still not enough. This review will briefly summarize the process of ferroptosis and introduce critical molecules in the ferroptotic cascade. Furthermore, we reviewed the occurrence and regulation of reduction-oxidation (redox) for ferroptosis in cancer metabolism. The role of the tumor suppressor and the epigenetic regulator in tumor cell ferroptosis will also be described. Finally, old drugs that can be repurposed to induce ferroptosis will be characterized, aiming for drug repurposing and novel drug combinations for cancer therapy more efficiently and economically. 10.1155/2020/8810785
    Ferroptosis: past, present and future. Li Jie,Cao Feng,Yin He-Liang,Huang Zi-Jian,Lin Zhi-Tao,Mao Ning,Sun Bei,Wang Gang Cell death & disease Ferroptosis is a new type of cell death that was discovered in recent years and is usually accompanied by a large amount of iron accumulation and lipid peroxidation during the cell death process; the occurrence of ferroptosis is iron-dependent. Ferroptosis-inducing factors can directly or indirectly affect glutathione peroxidase through different pathways, resulting in a decrease in antioxidant capacity and accumulation of lipid reactive oxygen species (ROS) in cells, ultimately leading to oxidative cell death. Recent studies have shown that ferroptosis is closely related to the pathophysiological processes of many diseases, such as tumors, nervous system diseases, ischemia-reperfusion injury, kidney injury, and blood diseases. How to intervene in the occurrence and development of related diseases by regulating cell ferroptosis has become a hotspot and focus of etiological research and treatment, but the functional changes and specific molecular mechanisms of ferroptosis still need to be further explored. This paper systematically summarizes the latest progress in ferroptosis research, with a focus on providing references for further understanding of its pathogenesis and for proposing new targets for the treatment of related diseases. 10.1038/s41419-020-2298-2