[Poisonings with Amanita phalloides].
Ferenc Tomasz,Lukasiewicz Beata,Ciećwierz Julita,Kowalczyk Edward
Medycyna pracy
Amanita phalloides is the most dangerous, poisonous mushroom species in our climatic conditions. It is the cause of 90-95% of all deaths due to mushroom poisoning, a-Amanitin, a polymerase RNA II inhibitor, is mainly responsible for the Amanita phalloides toxic property. Inhibition of polymerase RNA II functioning in a transcription process is connected with inhibition biosynthesis of structural and enzymatic proteins in cells. A lethal dose of a-amanitin is 0.1 mg/kg b.w. for humans. One of the medical problems in Amanita phalloides poisonings is a relatively prolonged latency period (8-24 h) from mushroom ingestion, at the same time the cytotropic action of absorbed toxins is revealed. In severe cases, multi organ failure, renal and hepatitis failure can occur. Deaths in a-amanitin poising cases follows between 6-16 days after intoxication. Mortality in this group of patients is still high and amounts to approximately 20-30% in adults and exceeds 50% in children. If mushroom poisoning occurs, it is best treated with pharmacological agents, extracorporeal methods for toxin removal and liver transplantation. Recent high expectations concerning liver albumin dialysis (based on MARS) should support liver regeneration and will also help with possible liver transplantation. In a medical community it is generally believed that every suspected Amanita phalloides poisoning should be referred to a specialized health center.
mTORC2: The other mTOR in autophagy regulation.
Ballesteros-Álvarez Josué,Andersen Julie K
Aging cell
The mechanistic target of rapamycin (mTOR) has gathered significant attention as a ubiquitously expressed multimeric kinase with key implications for cell growth, proliferation, and survival. This kinase forms the central core of two distinct complexes, mTORC1 and mTORC2, which share the ability of integrating environmental, nutritional, and hormonal cues but which regulate separate molecular pathways that result in different cellular responses. Particularly, mTORC1 has been described as a major negative regulator of endosomal biogenesis and autophagy, a catabolic process that degrades intracellular components and organelles within the lysosomes and is thought to play a key role in human health and disease. In contrast, the role of mTORC2 in the regulation of autophagy has been considerably less studied despite mounting evidence this complex may regulate autophagy in a different and perhaps complementary manner to that of mTORC1. Genetic ablation of unique subunits is currently being utilized to study the differential effects of the two mTOR complexes. RICTOR is the best-described subunit specific to mTORC2 and as such has become a useful tool for investigating the specific actions of this complex. The development of complex-specific inhibitors for mTORC2 is also an area of intense interest. Studies to date have demonstrated that mTORC1/2 complexes each signal to a variety of exclusive downstream molecules with distinct biological roles. Pinpointing the particular effects of these downstream effectors is crucial toward the development of novel therapies aimed at accurately modulating autophagy in the context of human aging and disease.
10.1111/acel.13431
Regulation of Autophagy by mTOR Signaling Pathway.
Wang Ying,Zhang Hongbing
Advances in experimental medicine and biology
Autophagy plays a crucial role in maintaining cellular homeostasis, and is closely related to the occurrence of variety of human diseases. It is known that autophagy occurs in response to various environmental stresses such as nutrient deficiency, growth factor deficiency, and hypoxia. Induced autophagy eliminates the damage caused by these stresses and returns to normal levels when the stresses are relieved. To comprehend the induction of autophagy under various stress conditions and the effects of autophagy on the life processes of cells, it is necessary to understand how autophagy is regulated. Many studies have shown that a number of signal transduction pathways are involved in the regulation of autophagy. Among these pathways, some pathways converge at the target of rapamycin (TOR), a highly conserved kinase important for autophagy regulation. This review will focus on the role of TOR signaling pathway in the regulation of autophagy.
10.1007/978-981-15-0602-4_3
The Upstream Pathway of mTOR-Mediated Autophagy in Liver Diseases.
Cells
Autophagy, originally found in liver experiments, is a cellular process that degrades damaged organelle or protein aggregation. This process frees cells from various stress states is a cell survival mechanism under stress stimulation. It is now known that dysregulation of autophagy can cause many liver diseases. Therefore, how to properly regulate autophagy is the key to the treatment of liver injury. mechanistic target of rapamycin (mTOR)is the core hub regulating autophagy, which is subject to different upstream signaling pathways to regulate autophagy. This review summarizes three upstream pathways of mTOR: the phosphoinositide 3-kinase (PI3K)/protein kinase (AKT) signaling pathway, the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway, and the rat sarcoma (Ras)/rapidly accelerated fibrosarcoma (Raf)/mitogen-extracellular activated protein kinase kinase (MEK)/ extracellular-signal-regulated kinase (ERK) signaling pathway, specifically explored their role in liver fibrosis, hepatitis B, non-alcoholic fatty liver, liver cancer, hepatic ischemia reperfusion and other liver diseases through the regulation of mTOR-mediated autophagy. Moreover, we also analyzed the crosstalk between these three pathways, aiming to find new targets for the treatment of human liver disease based on autophagy.
10.3390/cells8121597
mTOR: a pharmacologic target for autophagy regulation.
The Journal of clinical investigation
mTOR, a serine/threonine kinase, is a master regulator of cellular metabolism. mTOR regulates cell growth and proliferation in response to a wide range of cues, and its signaling pathway is deregulated in many human diseases. mTOR also plays a crucial role in regulating autophagy. This Review provides an overview of the mTOR signaling pathway, the mechanisms of mTOR in autophagy regulation, and the clinical implications of mTOR inhibitors in disease treatment.
10.1172/JCI73939
Paeoniflorin protects hepatocytes from APAP-induced damage through launching autophagy via the MAPK/mTOR signaling pathway.
Cellular & molecular biology letters
BACKGROUND:Drug-induced liver injury (DILI) is gradually becoming a common global problem that causes acute liver failure, especially in acute hepatic damage caused by acetaminophen (APAP). Paeoniflorin (PF) has a wide range of therapeutic effects to alleviate a variety of hepatic diseases. However, the relationship between them is still poorly investigated in current studies. PURPOSE:This work aimed to explore the protective effects of PF on APAP-induced hepatic damage and researched the potential molecular mechanisms. METHODS:C57BL/6J male mice were injected with APAP to establish DILI model and were given PF for five consecutive days for treatment. Aiming to clarify the pharmacological effects, the molecular mechanisms of PF in APAP-induced DILI was elucidated by high-throughput and other techniques. RESULTS:The results demonstrated that serum levels of ALP, γ-GT, AST, TBIL, and ALT were decreased in APAP mice by the preventive effects of PF. Moreover, PF notably alleviated hepatic tissue inflammation and edema. Meanwhile, the results of TUNEL staining and related apoptotic factors coincided with the results of transcriptomics, suggesting that PF inhibited hepatocyte apoptosis by regulated MAPK signaling. Besides, PF also acted on reactive oxygen species (ROS) to regulate the oxidative stress for recovery the damaged mitochondria. More importantly, transmission electron microscopy showed the generation of autophagosomes after PF treatment, and PF was also downregulated mTOR and upregulated the expression of autophagy markers such as ATG5, ATG7, and BECN1 at the mRNA level and LC3, p62, ATG5, and ATG7 at the protein level, implying that the process by which PF exerted its effects was accompanied by the occurrence of autophagy. In addition, combinined with molecular dynamics simulations and western blotting of MAPK, the results suggested p38 as a direct target for PF on APAP. Specifically, PF-activated autophagy through the downregulation of MAPK/mTOR signaling, which in turn reduced APAP injury. CONCLUSIONS:Paeoniflorin mitigated liver injury by activating autophagy to suppress oxidative stress and apoptosis via the MAPK/mTOR signaling pathway. Taken together, our findings elucidate the role and mechanism of paeoniflorin in DILI, which is expected to provide a new therapeutic strategy for the development of paeoniflorin.
10.1186/s11658-024-00631-4
mTOR activation protects liver from ischemia/reperfusion-induced injury through NF-κB pathway.
Li Ziru,Zhang Jing,Mulholland Michael,Zhang Weizhen
FASEB journal : official publication of the Federation of American Societies for Experimental Biology
Hepatic steatosis renders liver more vulnerable to ischemia/reperfusion injury (IRI), which commonly occurs in transplantation, trauma, and liver resection. The underlying mechanism is not fully characterized. We aimed to clarify the role of mechanistic target of rapamycin (mTOR) signaling in hepatic ischemia/reperfusion injury (HIRI) in normal and steatotic liver using - (AT) and (Am) transgenic mice. Steatotic liver induced by high-fat diet was more vulnerable to IRI. Activation of hepatic mTOR in AT mice decreased lipid accumulation attenuated HIRI as measured by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining, circulating levels of alanine aminotransferase and lactate dehydrogenase, and inflammatory mediators such as monocyte chemoattractant protein 1 (MCP-1), TNF-α, and IL-6 and hepatic cleaved caspase 3 in mice fed either a normal chow diet or a high-fat diet. The effects of mTOR activation on hepatic cleaved caspase 3 were reversed by rapamycin, an inhibitor of mTOR signaling. Inhibition of hepatic mTOR in Am mice increased hepatic lipid deposition and HIRI. The increment in hepatic susceptibility to IRI was significantly attenuated by pretreatment with IKKβ inhibitor. Further, suppression of mTOR facilitated nuclear translocation of NF-κB p65. In conclusion, our study suggests that mTOR activity in hepatocytes decreases hepatic vulnerability to injury through a mechanism dependent on NF-κB proinflammatory cytokine signaling pathway in both normal and steatotic liver.-Li, Z., Zhang, J., Mulholland, M., Zhang, W. mTOR activation protects liver from ischemia/reperfusion-induced injury through NF-κB pathway.
10.1096/fj.201601278R
The double-edged sword of MTOR in autophagy deficiency induced-liver injury and tumorigenesis.
Yang Hua,Ni Hong-Min,Ding Wen-Xing
Autophagy
Liver-specific deletion of autophagy-related genes in mice leads to hepatomegaly, liver injury and spontaneous liver tumorigenesis. Accumulating evidence indicates that p62/SQSTM1-mediated NFE2L2/Nrf2/(nuclear factor, erythroid 2 like 2) activation plays a critical role in promoting liver injury and tumorigenesis in autophagy-defective livers. However, the mechanisms of how persistent NFE2L2 activation induces liver injury and tumorigenesis are unknown. In a recent study, it was found that deletion of (mechanistic target of rapamycin kinase) or attenuates hepatomegaly and liver injury in young liver-specific knockout mice but accelerates liver tumorigenesis in old mice likely due to feedback AKT activation. Overall, these findings suggest that both hyper- and hypo-activation of MTOR are detrimental to the liver resulting in the development of liver tumors. A balanced MTOR activity is critical to maintain the normal physiological functions of the liver, and caution should be exercised when treating hepatocellular carcinomas using MTOR inhibitors. Atg5: autophgy related 5; DKO: double-knockout; HCC: hepatocellular carcinoma; INS: insulin; INSR: insulin receptor; KEAP1: kelch-like ECH-associated protein 1; KO: knockout; MTOR: mechanistic target of rapamycin kinase; NFE2L2: nuclear factor, erythroid 2 like 2; raptor: regulatory associated protein of MTOR, complex 1; SQSTM1: sequestosome 1: tsc1: TSC complex subunit 1.
10.1080/15548627.2019.1634445
Targeting ferroptosis by poly(acrylic) acid coated MnO nanoparticles alleviates acute liver injury.
Nature communications
Ferroptosis, a newly characterized form of regulated cell death, is induced by excessive accumulation of lipid peroxidation catalyzed by intracellular bioactive iron. Increasing evidence has suggested that ferroptosis is involved in the pathogenesis of several human diseases, including acute liver injury. Targeted inhibition of ferroptosis holds great promise for the clinical treatment of these diseases. Herein, we report a simple and one-pot synthesis of ultrasmall poly(acrylic) acid coated MnO nanoparticles (PAA@MnO-NPs, PMO), which perform multiple antioxidant enzyme-mimicking activities and can scavenge broad-spectrum reactive oxygen species. PMO could potently suppress ferroptosis. Mechanistically, after being absorbed mainly through macropinocytosis, PMO are largely enriched in lysosomes, where PMO detoxify ROS, inhibit ferritinophagy-mediated iron mobilization and preserve mTOR activation, which collectively confer the prominent inhibition of ferroptosis. Additionally, PMO injection potently counteracts lipid peroxidation and alleviates acetaminophen- and ischaemia/reperfusion-induced acute liver injury in mice. Collectively, our results reveal that biocompatible PMO act as potent ferroptosis inhibitors through multifaceted mechanisms, which ensures that PMO have great translational potential for the clinical treatment of ferroptosis-related acute liver injury.
10.1038/s41467-023-43308-w
Impaired TFEB-Mediated Lysosome Biogenesis and Autophagy Promote Chronic Ethanol-Induced Liver Injury and Steatosis in Mice.
Chao Xiaojuan,Wang Shaogui,Zhao Katrina,Li Yuan,Williams Jessica A,Li Tiangang,Chavan Hemantkumar,Krishnamurthy Partha,He Xi C,Li Linheng,Ballabio Andrea,Ni Hong-Min,Ding Wen-Xing
Gastroenterology
BACKGROUND & AIMS:Defects in lysosome function and autophagy contribute to the pathogenesis of alcoholic liver disease. We investigated the mechanisms by which alcohol consumption affects these processes by evaluating the functions of transcription factor EB (TFEB), which regulates lysosomal biogenesis. METHODS:We performed studies with GFP-LC3 mice, mice with liver-specific deletion of TFEB, mice with disruption of the transcription factor E3 gene (TFE3-knockout mice), mice with disruption of the Tefb and Tfe3 genes (TFEB and TFE3 double-knockout mice), and Tfeb albumin cre-negative mice (controls). TFEB was overexpressed from adenoviral vectors or knocked down with small interfering RNAs in mouse livers. Mice were placed on diets of regular ethanol feeding plus an acute binge to induce liver damage (ethanol diet); some mice also were given injections of torin-1, an inhibitor of the kinase activity of the mechanistic target of rapamycin (mTOR). Liver tissues were collected and analyzed by immunohistochemistry, immunoblots, and quantitative real-time polymerase chain reaction to monitor lysosome biogenesis. We analyzed levels of TFEB in liver tissues from patients with alcoholic hepatitis and from healthy donors (controls) by immunohistochemistry. RESULTS:Liver tissues from mice on the ethanol diet had lower levels of total and nuclear TFEB compared with control mice, and hepatocytes had decreased lysosome biogenesis and autophagy. Hepatocytes from mice on the ethanol diet had increased translocation of mTOR into lysosomes, resulting in increased mTOR activation. Administration of torin-1 increased liver levels of TFEB and decreased steatosis and liver injury induced by ethanol. Mice that overexpressed TFEB in the liver developed less severe ethanol-induced liver injury and had increased lysosomal biogenesis and mitochondrial bioenergetics compared with mice carrying a control vector. Mice with knockdown of TFEB and TFEB-TFE3 double-knockout mice developed more severe liver injury in response to the ethanol diet than control mice. Liver tissues from patients with alcohol-induced hepatitis had lower nuclear levels of TFEB than control tissues. CONCLUSIONS:We found that ethanol feeding plus an acute binge decreased hepatic expression of TFEB, which is required for lysosomal biogenesis and autophagy. Strategies to block mTOR activity or increase levels of TFEB might be developed to protect the liver from ethanol-induced damage.
10.1053/j.gastro.2018.05.027
The Translational Regulation in mTOR Pathway.
Biomolecules
The mechanistic/mammalian target of rapamycin (mTOR) plays a master role in cell proliferation and growth in response to insulin, amino acids, energy levels, and oxygen. mTOR can coordinate upstream signals with downstream effectors, including transcriptional and translational apparatuses to regulate fundamental cellular processes such as energy utilization, protein synthesis, autophagy, cell growth, and proliferation. Of the above, protein synthesis is highly energy-consuming; thus, mRNA translation is under the tight and immediate control of mTOR signaling. The translational regulation driven by mTOR signaling mainly relies on eukaryotic translation initiation factor 4E (eIF4E)-binding protein (4E-BP), ribosomal protein S6 kinase (S6K), and its downstream players, which are significant in rapid cellular response to environmental change. mTOR signaling not only controls the general mRNA translation, but preferential mRNA translation as well. This means that mTOR signaling shows the stronger selectivity to particular target mRNAs. Some evidence has supported the contribution of 4E-BP and La-related proteins 1 (LARP1) to such translational regulation. In this review, we summarize the mTOR pathway and mainly focus on mTOR-mediated mRNA translational regulation. We introduce the major components of mTOR signaling and their functions in translational control in a general or particular manner, and describe how the specificity of regulation is coordinated. Furthermore, we summarize recent research progress and propose additional ideas for reference. Because the mTOR pathway is on the center of cell growth and metabolism, comprehensively understanding this pathway will contribute to the therapy of related diseases, including cancers, type 2 diabetes, obesity, and neurodegeneration.
10.3390/biom12060802