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    Protein Ubiquitination Research in Oncology. Faktor J,Pjechová M,Hernychová L,Vojtěšek B Klinicka onkologie : casopis Ceske a Slovenske onkologicke spolecnosti BACKGROUND:Ubiquitination is a vital posttranslational protein modification involved in the regulation of many eukaryotic signalling pathways. Aberrant ubiquitin signalling is known to be a molecular causality of certain cancer, neurodegenerative, immune system or cardiovascular diseases. The recent development of mass spectrometry methods enables qualitative and quantitative ubiquitination analysis in biological material from cancer patients. Research of ubiquitination may clarify the molecular cause of aberrant changes in the protein level of tumour suppressors or oncogenes. PURPOSE:We aim to explain the meaning and importance of ubiquitination in certain molecular processes taking place in the human body. We hereby emphasise the connection between ubiquitination and malignant processes. A literature search is followed by introducing our mass spectrometry platform intended for ubiquitin identification via diglycyl remnants in the CHIP protein sequence. The aim is to introduce tandem mass spectrometry identification of ubiquitin modification, ubiquitination tandem mass spectra validation and the time-dependent manner of CHIP ubiquitination to the reader. CONCLUSION:A literature search familiarises the reader with known mechanisms of aberrant ubiquitination in malignant diseases. A successfully optimised mass spectrometry platform could serve as a potent tool for determining ubiquitin position in proteins that are a part of real tumour samples. 10.14735/amko20193S
    In Vitro Ubiquitination and Deubiquitination Assays of Nucleosomal Histones. Masclef Louis,Maxime Uriarte,Ahmed Oumaima,Sen Nkwe Nadine,Barbour Haithem,Iannantuono Nicholas V G,Boubekeur Amina,Daou Salima,Affar El Bachir Journal of visualized experiments : JoVE Ubiquitination is a post-translational modification that plays important roles in various signaling pathways and is notably involved in the coordination of chromatin function and DNA-associated processes. This modification involves a sequential action of several enzymes including E1 ubiquitin-activating, E2 ubiquitin-conjugating and E3 ubiquitin-ligase and is reversed by deubiquitinases (DUBs). Ubiquitination induces degradation of proteins or alteration of protein function including modulation of enzymatic activity, protein-protein interaction and subcellular localization. A critical step in demonstrating protein ubiquitination or deubiquitination is to perform in vitro reactions with purified components. Effective ubiquitination and deubiquitination reactions could be greatly impacted by the different components used, enzyme co-factors, buffer conditions, and the nature of the substrate.  Here, we provide step-by-step protocols for conducting ubiquitination and deubiquitination reactions. We illustrate these reactions using minimal components of the mouse Polycomb Repressive Complex 1 (PRC1), BMI1, and RING1B, an E3 ubiquitin ligase that monoubiquitinates histone H2A on lysine 119. Deubiquitination of nucleosomal H2A is performed using a minimal Polycomb Repressive Deubiquitinase (PR-DUB) complex formed by the human deubiquitinase BAP1 and the DEUBiquitinase ADaptor (DEUBAD) domain of its co-factor ASXL2. These ubiquitination/deubiquitination assays can be conducted in the context of either recombinant nucleosomes reconstituted with bacteria-purified proteins or native nucleosomes purified from mammalian cells. We highlight the intricacies that can have a significant impact on these reactions and we propose that the general principles of these protocols can be swiftly adapted to other E3 ubiquitin ligases and deubiquitinases. 10.3791/59385
    Ubiquitination by HUWE1 in tumorigenesis and beyond. Kao Shih-Han,Wu Han-Tsang,Wu Kou-Juey Journal of biomedical science Ubiquitination modulates a large repertoire of cellular functions and thus, dysregulation of the ubiquitin system results in multiple human diseases, including cancer. Ubiquitination requires an E3 ligase, which is responsible for substrate recognition and conferring specificity to ubiquitination. HUWE1 is a multifaceted HECT domain-containing ubiquitin E3 ligase, which catalyzes both mono-ubiquitination and K6-, K48- and K63-linked poly-ubiquitination of its substrates. Many of the substrates of HUWE1 play a crucial role in maintaining the homeostasis of cellular development. Not surprisingly, dysregulation of HUWE1 is associated with tumorigenesis and metastasis. HUWE1 is frequently overexpressed in solid tumors, but can be downregulated in brain tumors, suggesting that HUWE1 may possess differing cell-specific functions depending on the downstream targets of HUWE1. This review introduces some important discoveries of the HUWE1 substrates, including those controlling proliferation and differentiation, apoptosis, DNA repair, and responses to stress. In addition, we review the signaling pathways HUWE1 participates in and obstacles to the identification of HUWE1 substrates. We also discuss up-to-date potential therapeutic designs using small molecules or ubiquitin variants (UbV) against the HUWE1 activity. These molecular advances provide a translational platform for future bench-to-bed studies. HUWE1 is a critical ubiquitination modulator during the tumor progression and may serve as a possible therapeutic target for cancer treatment. 10.1186/s12929-018-0470-0
    [Research Progress of the Roles of Ubiquitination/Deubiquitination in Androgen Receptor Abnormalities and Prostate Cancer]. Zhang Wei-Yu,Zhou Jian-Hua,Wang Huan-Rui,Mu Qing,Wang Qi,Xu Ke-Xin,Xu Tao,Hu Hao Zhongguo yi xue ke xue yuan xue bao. Acta Academiae Medicinae Sinicae Ubiquitin is a small molecule protein consisting of 76 amino acids,widely found in eukaryotic cells. The process by which ubiquitin binding to a specific protein is called ubiquitination. Deubiquitination is the reversed process of ubiquitination. Ubiquitination stimulates downstream signal,including complex assembly,protein conformation and activity changes,proteolysis,autophagy,guilt,chromatin remodeling,and DNA repair. More than 80% of eukaryotic protein degradation is mediated by the ubiquitination system,and ubiquitin-dependent proteolysis is an extremely complex process involving many biomolecular processes. By regulating protein homeostasis,ubiquitination can also regulate a variety of biological processes including cell cycle,cell proliferation,and apoptosis,which are closely related to tumorigenesis and progression. Many abnormalities of androgen receptor (AR) including AR gene amplification,mutation,shear mutation,and AR activity enhancement are closely related to prostate cancer progression. In particular,prostate cancer progression is regulated by the ubiquitination/deubiquitination processes. This article summarizes the recent research advances in the roles of ubiquitination/deubiquitination in AR abnormalities and prostate cancer. 10.3881/j.issn.1000-503X.11069
    Linear ubiquitination of cFLIP induced by LUBAC contributes to TNFα-induced apoptosis. Tang Yong,Joo Donghyun,Liu Guangna,Tu Hailin,You Jeffrey,Jin Jianping,Zhao Xueqiang,Hung Mien-Chie,Lin Xin The Journal of biological chemistry The linear ubiquitin chain assembly complex (LUBAC) regulates NF-κB activation by modifying proteins with linear (M1-linked) ubiquitination chains. Although LUBAC also regulates the apoptosis pathway, the precise mechanism by which LUBAC regulates apoptosis remains not fully defined. Here, we report that LUBAC-mediated M1-linked ubiquitination of cellular FLICE-like inhibitory protein (cFLIP), an anti-apoptotic molecule, contributes to tumor necrosis factor (TNF) α-induced apoptosis. We found that deficiency of RNF31, the catalytic subunit of the LUBAC complex, promoted cFLIP degradation in a proteasome-dependent manner. Moreover, we observed RNF31 directly interact with cFLIP, and LUBAC further conjugated M1-linked ubiquitination chains at Lys-351 and Lys-353 of cFLIP to stabilize cFLIP, thereby protecting cells from TNFα-induced apoptosis. Together, our study identifies a new substrate of LUBAC and reveals a new molecular mechanism through which LUBAC regulates TNFα-induced apoptosis via M1-linked ubiquitination. 10.1074/jbc.RA118.005449
    Mdm2-mediated ubiquitination of PKCβII in the nucleus mediates clathrin-mediated endocytic activity. Min Xiao,Zhang Xiaohan,Sun Ningning,Acharya Srijan,Kim Kyeong-Man Biochemical pharmacology Cellular stimuli that increase diacylglycerol levels activate several protein kinase C (PKC) isoforms; however, prolonged stimulation depletes cells of PKCs. Ubiquitination is a critical cellular event that mediates the degradation of numerous proteins, including PKCs, but little is known of the molecular mechanisms involved in PKC ubiquitination. PKCβII is the most widely expressed PKC isoform and regulates a variety of cellular functions. Here, we show that in response to stimulation of the Gq-coupled angiotensin II type 1 receptor or treatment with phorbol ester, Mdm2, E3 ubiquitin ligase, interacted with PKCβII isotype in the nucleus, resulting in ubiquitination of PKCβII at the C-terminal K668 and K672 residues and its subsequent downregulation. Ubiquitinated PKCβII mediated the clathrin-mediated endocytosis of G protein-coupled receptors like the D and D dopamine receptors; in contrast, non-ubiquitinated PKCβII mediated an as yet uncharacterized clathrin- and caveolar-independent endocytic pathway. In conclusion, we characterized the molecular mechanisms involved in the activity-dependent ubiquitination of PKCβII that determine its life span and endocytic roles. Considering that PKCβII plays an important role in the development of various diseases, including diabetic vasculitis, the results obtained in this study will contribute to better understanding the pathogenesis of PKCβII-related diseases. 10.1016/j.bcp.2019.113675
    The roles of ubiquitination in extrinsic cell death pathways and its implications for therapeutics. Seo Jinho,Kim Min Wook,Bae Kwang-Hee,Lee Sang Chul,Song Jaewhan,Lee Eun-Woo Biochemical pharmacology Regulation of cell survival and death, including apoptosis and necroptosis, is important for normal development and tissue homeostasis, and disruption of these processes can cause cancer, inflammatory diseases, and degenerative diseases. Ubiquitination is a cellular process that induces proteasomal degradation by covalently attaching ubiquitin to the substrate protein. In addition to proteolytic ubiquitination, nonproteolytic ubiquitination, such as M1-linked and K63-linked ubiquitination, has been shown to be important in recent studies, which have demonstrated its function in cell signaling pathways that regulate inflammation and cell death pathways. In this review, we summarize the TRAIL- and TNF-induced death receptor signaling pathways along with recent advances in this field and illustrate how different types of ubiquitination control cell death and survival. In particular, we provide an overview of the different types of ubiquitination, target residues, and modifying enzymes, including E3 ligases and deubiquitinating enzymes. Given the relevance of these regulatory pathways in human disease, we hope that a better understanding of the regulatory mechanisms of cell death pathways will provide insights into and therapeutic strategies for related diseases. 10.1016/j.bcp.2018.11.012
    Ubiquitination of IgG1 cytoplasmic tail modulates B-cell signalling and activation. Kodama Tadahiro,Hasegawa Mika,Sakamoto Yui,Haniuda Kei,Kitamura Daisuke International immunology Upon antigen stimulation, IgG+ B cells rapidly proliferate and differentiate into plasma cells, which has been attributed to the characteristics of membrane-bound IgG (mIgG), but the underlying molecular mechanisms remain elusive. We have found that a part of mouse mIgG1 is ubiquitinated through the two responsible lysine residues (K378 and K386) in its cytoplasmic tail and this ubiquitination is augmented upon antigen stimulation. The ubiquitination of mIgG1 involves its immunoglobulin tail tyrosine (ITT) motif, Syk/Src-family kinases and Cbl proteins. Analysis of a ubiquitination-defective mutant of mIgG1 revealed that ubiquitination of mIgG1 facilitates its ligand-induced endocytosis and intracellular trafficking from early endosome to late endosome, and also prohibits the recycling pathway, thus attenuating the surface expression level of mIgG1. Accordingly, ligation-induced activation of B-cell receptor (BCR) signalling molecules is attenuated by the mIgG1 ubiquitination, except MAP kinase p38 whose activation is up-regulated due to the ubiquitination-mediated prohibition of mIgG1 recycling. Adaptive transfer experiments demonstrated that ubiquitination of mIgG1 facilitates expansion of germinal centre B cells. These results indicate that mIgG1-mediated signalling and cell activation is regulated by ubiquitination of mIgG1, and such regulation may play a role in expansion of germinal centre B cells. 10.1093/intimm/dxaa009
    Novel strategies to target the ubiquitin proteasome system in multiple myeloma. Lub Susanne,Maes Ken,Menu Eline,De Bruyne Elke,Vanderkerken Karin,Van Valckenborgh Els Oncotarget Multiple myeloma (MM) is a hematological malignancy characterized by the accumulation of plasma cells in the bone marrow (BM). The success of the proteasome inhibitor bortezomib in the treatment of MM highlights the importance of the ubiquitin proteasome system (UPS) in this particular cancer. Despite the prolonged survival of MM patients, a significant amount of patients relapse or become resistant to therapy. This underlines the importance of the development and investigation of novel targets to improve MM therapy. The UPS plays an important role in different cellular processes by targeted destruction of proteins. The ubiquitination process consists of enzymes that transfer ubiquitin to proteins targeting them for proteasomal degradation. An emerging and promising approach is to target more disease specific components of the UPS to reduce side effects and overcome resistance. In this review, we will focus on different components of the UPS such as the ubiquitin activating enzyme E1, the ubiquitin conjugating enzyme E2, the E3 ubiquitin ligases, the deubiquitinating enzymes (DUBs) and the proteasome. We will discuss their role in MM and the implications in drug discovery for the treatment of MM. 10.18632/oncotarget.6658
    Resistance to the Proteasome Inhibitors: Lessons from Multiple Myeloma and Mantle Cell Lymphoma. Gonzalez-Santamarta Maria,Quinet Grégoire,Reyes-Garau Diana,Sola Brigitte,Roué Gaël,Rodriguez Manuel S Advances in experimental medicine and biology Since its introduction in the clinics in early 2000s, the proteasome inhibitor bortezomib (BTZ) significantly improved the prognosis of patients with multiple myeloma (MM) and mantle cell lymphoma (MCL), two of the most challenging B cell malignancies in western countries. However, relapses following BTZ therapy are frequent, while primary resistance to this agent remains a major limitation for further development of its therapeutic potential. In the present chapter, we recapitulate the molecular mechanisms associated with intrinsic and acquired resistance to BTZ learning from MM and MCL experience, including mutations of crucial genes and activation of prosurvival signalling pathways inherent to malignant B cells. We also outline the preclinical and clinical evaluations of some potential druggable targets associated to BTZ resistance, considering the most meaningful findings of the past 10 years. Although our understanding of BTZ resistance is far from being completed, recent discoveries are contributing to develop new approaches to treat relapsed MM and MCL patients. 10.1007/978-3-030-38266-7_6