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Shao S, Zhou D, Feng J, Liu Y, Baturuhu, Yin H, Zhan D. Regulation of inflammation and immunity in sepsis by E3 ligases. Front Endocrinol (Lausanne) 2023; 14:1124334. [PMID: 37465127 PMCID: PMC10351979 DOI: 10.3389/fendo.2023.1124334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 06/16/2023] [Indexed: 07/20/2023] Open
Abstract
Sepsis is a life-threatening organ dysfunction caused by an abnormal infection-induced immune response. Despite significant advances in supportive care, sepsis remains a considerable therapeutic challenge and is the leading cause of death in the intensive care unit (ICU). Sepsis is characterized by initial hyper-inflammation and late immunosuppression. Therefore, immune-modulatory therapies have great potential for novel sepsis therapies. Ubiquitination is an essential post-translational protein modification, which has been known to be intimately involved in innate and adaptive immune responses. Several E3 ubiquitin ligases have been implicated in innate immune signaling and T-cell activation and differentiation. In this article, we review the current literature and discuss the role of E3 ligases in the regulation of immune response and their effects on the course of sepsis to provide insights into the prevention and therapy for sepsis.
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Affiliation(s)
- Shasha Shao
- Department of Emergency Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Department of Critical Care Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Daixing Zhou
- Department of Emergency Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Department of Critical Care Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jun Feng
- Department of Emergency Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Department of Critical Care Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yanyan Liu
- Obstetrics and Gynecology Department, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Baturuhu
- Department of Neurosurgery Intensive Care Unit (ICU), People’s Hospital of Bortala Mongol Autonomous Prefecture, Bole, China
| | - Huimei Yin
- Department of Emergency Medicine, People’s Hospital of Bortala Mongol Autonomous Prefecture, Bole, China
| | - Daqian Zhan
- Department of Emergency Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Department of Critical Care Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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2
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Kowluru A, Gleason NF. Underappreciated roles for Rho GDP dissociation inhibitors (RhoGDIs) in cell function: Lessons learned from the pancreatic islet β-cell. Biochem Pharmacol 2022; 197:114886. [PMID: 34968495 PMCID: PMC8858860 DOI: 10.1016/j.bcp.2021.114886] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/10/2021] [Accepted: 12/13/2021] [Indexed: 11/02/2022]
Abstract
Rho subfamily of G proteins (e.g., Rac1) have been implicated in glucose-stimulated insulin secretion from the pancreatic β-cell. Interestingly, metabolic stress (e.g., chronic exposure to high glucose) results in sustained activation of Rac1 leading to increased oxidative stress, impaired insulin secretion and β-cell dysfunction. Activation-deactivation of Rho G proteins is mediated by three classes of regulatory proteins, namely the guanine nucleotide exchange factors (GEFs), which facilitate the conversion of inactive G proteins to their active conformations; the GTPase-activating proteins (GAPs), which convert the active G proteins to their inactive forms); and the GDP-dissociation inhibitors (GDIs), which prevent the dissociation of GDP from G proteins. Contrary to a large number of GEFs (82 members) and GAPs (69 members), only three members of RhoGDIs (RhoGDIα, RhoGDIβ and RhoGDIγ) are expressed in mammalian cells.Even though relatively smaller in number, the GDIs appear to play essential roles in G protein function (e.g., subcellular targeting) for effector activation and cell regulation. Emerging evidence also suggests that the GDIs are functionally regulated via post-translational modification (e.g., phosphorylation) and by lipid second messengers, lipid kinases and lipid phosphatases. We highlight the underappreciated regulatory roles of RhoGDI-Rho G protein signalome in islet β-cell function in health and metabolic stress. Potential knowledge gaps in the field, and directions for future research for the identification of novel therapeutic targets to loss of functional β-cell mass under the duress of metabolic stress are highlighted.
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Affiliation(s)
- Anjaneyulu Kowluru
- Biomedical Research Service, John D. Dingell VA Medical Center and Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48201, USA.
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3
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Electrostatic Forces Mediate the Specificity of RHO GTPase-GDI Interactions. Int J Mol Sci 2021; 22:ijms222212493. [PMID: 34830380 PMCID: PMC8622166 DOI: 10.3390/ijms222212493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 01/13/2023] Open
Abstract
Three decades of research have documented the spatiotemporal dynamics of RHO family GTPase membrane extraction regulated by guanine nucleotide dissociation inhibitors (GDIs), but the interplay of the kinetic mechanism and structural specificity of these interactions is as yet unresolved. To address this, we reconstituted the GDI-controlled spatial segregation of geranylgeranylated RHO protein RAC1 in vitro. Various biochemical and biophysical measurements provided unprecedented mechanistic details for GDI function with respect to RHO protein dynamics. We determined that membrane extraction of RHO GTPases by GDI occurs via a 3-step mechanism: (1) GDI non-specifically associates with the switch regions of the RHO GTPases; (2) an electrostatic switch determines the interaction specificity between the C-terminal polybasic region of RHO GTPases and two distinct negatively-charged clusters of GDI1; (3) a non-specific displacement of geranylgeranyl moiety from the membrane sequesters it into a hydrophobic cleft, effectively shielding it from the aqueous milieu. This study substantially extends the model for the mechanism of GDI-regulated RHO GTPase extraction from the membrane, and could have implications for clinical studies and drug development.
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Gavali S, Liu J, Li X, Paolino M. Ubiquitination in T-Cell Activation and Checkpoint Inhibition: New Avenues for Targeted Cancer Immunotherapy. Int J Mol Sci 2021; 22:10800. [PMID: 34639141 PMCID: PMC8509743 DOI: 10.3390/ijms221910800] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/27/2021] [Accepted: 09/28/2021] [Indexed: 12/15/2022] Open
Abstract
The advent of T-cell-based immunotherapy has remarkably transformed cancer patient treatment. Despite their success, the currently approved immunotherapeutic protocols still encounter limitations, cause toxicity, and give disparate patient outcomes. Thus, a deeper understanding of the molecular mechanisms of T-cell activation and inhibition is much needed to rationally expand targets and possibilities to improve immunotherapies. Protein ubiquitination downstream of immune signaling pathways is essential to fine-tune virtually all immune responses, in particular, the positive and negative regulation of T-cell activation. Numerous studies have demonstrated that deregulation of ubiquitin-dependent pathways can significantly alter T-cell activation and enhance antitumor responses. Consequently, researchers in academia and industry are actively developing technologies to selectively exploit ubiquitin-related enzymes for cancer therapeutics. In this review, we discuss the molecular and functional roles of ubiquitination in key T-cell activation and checkpoint inhibitory pathways to highlight the vast possibilities that targeting ubiquitination offers for advancing T-cell-based immunotherapies.
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Affiliation(s)
| | | | | | - Magdalena Paolino
- Center for Molecular Medicine, Department of Medicine Solna, Karolinska Institutet, Karolinska University Hospital Solna, 17176 Solna, Sweden; (S.G.); (J.L.); (X.L.)
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5
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Beyond the Cell Surface: Targeting Intracellular Negative Regulators to Enhance T cell Anti-Tumor Activity. Int J Mol Sci 2019; 20:ijms20235821. [PMID: 31756921 PMCID: PMC6929154 DOI: 10.3390/ijms20235821] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 11/04/2019] [Accepted: 11/07/2019] [Indexed: 02/07/2023] Open
Abstract
It is well established that extracellular proteins that negatively regulate T cell function, such as Cytotoxic T-Lymphocyte-Associated protein 4 (CTLA-4) and Programmed Cell Death protein 1 (PD-1), can be effectively targeted to enhance cancer immunotherapies and Chimeric Antigen Receptor T cells (CAR-T cells). Intracellular proteins that inhibit T cell receptor (TCR) signal transduction, though less well studied, are also potentially useful therapeutic targets to enhance T cell activity against tumor. Four major classes of enzymes that attenuate TCR signaling include E3 ubiquitin kinases such as the Casitas B-lineage lymphoma proteins (Cbl-b and c-Cbl), and Itchy (Itch), inhibitory tyrosine phosphatases, such as Src homology region 2 domain-containing phosphatases (SHP-1 and SHP-2), inhibitory protein kinases, such as C-terminal Src kinase (Csk), and inhibitory lipid kinases such as Src homology 2 (SH2) domain-containing inositol polyphosphate 5-phosphatase (SHIP) and Diacylglycerol kinases (DGKs). This review describes the mechanism of action of eighteen intracellular inhibitory regulatory proteins in T cells within these four classes, and assesses their potential value as clinical targets to enhance the anti-tumor activity of endogenous T cells and CAR-T cells.
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Cho HJ, Kim JT, Baek KE, Kim BY, Lee HG. Regulation of Rho GTPases by RhoGDIs in Human Cancers. Cells 2019; 8:cells8091037. [PMID: 31492019 PMCID: PMC6769525 DOI: 10.3390/cells8091037] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 09/02/2019] [Accepted: 09/03/2019] [Indexed: 12/15/2022] Open
Abstract
Rho GDP dissociation inhibitors (RhoGDIs) play important roles in various cellular processes, including cell migration, adhesion, and proliferation, by regulating the functions of the Rho GTPase family. Dissociation of Rho GTPases from RhoGDIs is necessary for their spatiotemporal activation and is dynamically regulated by several mechanisms, such as phosphorylation, sumoylation, and protein interaction. The expression of RhoGDIs has changed in many human cancers and become associated with the malignant phenotype, including migration, invasion, metastasis, and resistance to anticancer agents. Here, we review how RhoGDIs control the function of Rho GTPases by regulating their spatiotemporal activity and describe the regulatory mechanisms of the dissociation of Rho GTPases from RhoGDIs. We also discuss the role of RhoGDIs in cancer progression and their potential uses for therapeutic intervention.
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Affiliation(s)
- Hee Jun Cho
- Immunotherapy Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea.
| | - Jong-Tae Kim
- Immunotherapy Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea.
| | - Kyoung Eun Baek
- Immunotherapy Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea.
| | - Bo-Yeon Kim
- Anticancer Cancer Research Center, Korea Research Institute of Bioscience and Biotechnology, Cheongju 28116, Korea.
| | - Hee Gu Lee
- Immunotherapy Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea.
- Department of Biomolecular Science, University of Science and Technology (UST), Daejeon 34141, Korea.
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Fujita Y, Tinoco R, Li Y, Senft D, Ronai ZA. Ubiquitin Ligases in Cancer Immunotherapy - Balancing Antitumor and Autoimmunity. Trends Mol Med 2019; 25:428-443. [PMID: 30898473 DOI: 10.1016/j.molmed.2019.02.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 02/05/2019] [Accepted: 02/07/2019] [Indexed: 12/25/2022]
Abstract
Considerable progress has been made in understanding the contribution of E3 ubiquitin ligases to health and disease, including the pathogenesis of immunological disorders. Ubiquitin ligases exert exquisite spatial and temporal control over protein stability and function, and are thus crucial for the regulation of both innate and adaptive immunity. Given that immune responses can be both detrimental (autoimmunity) and beneficial (antitumor immunity), it is vital to understand how ubiquitin ligases maintain immunological homeostasis. Such knowledge could reveal novel mechanisms underlying immune regulation and identify new therapeutic approaches to enhance antitumor immunity and safeguard against autoimmunity.
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Affiliation(s)
- Yu Fujita
- National Cancer Institute (NCI) Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA; Present address: Division of Respiratory Medicine, Department of Internal Medicine, Jikei University School of Medicine, Tokyo 105-8461, Japan
| | - Roberto Tinoco
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, CA 92697, USA
| | - Yan Li
- National Cancer Institute (NCI) Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Daniela Senft
- Research Unit Apoptosis in Hematopoietic Stem Cells, Helmholtz Zentrum München, German Research Center for Environmental Health (HMGU), Munich, Germany
| | - Ze'ev A Ronai
- National Cancer Institute (NCI) Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA.
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Liu P, Hsieh P, Lin H, Liu T, Wu H, Chen C, Chen Y. Grail is involved in adipocyte differentiation and diet-induced obesity. Cell Death Dis 2018; 9:525. [PMID: 29743578 PMCID: PMC5943410 DOI: 10.1038/s41419-018-0596-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/04/2018] [Accepted: 04/16/2018] [Indexed: 01/24/2023]
Abstract
Grail is a crucial regulator of various biological processes, including the development of T-cell anergy, antiviral innate immune response, and cancer. However, the role of Grail in adipogenesis and obesity remains unclear. Here, we demonstrated that Grail knockdown in vitro leads to a decrease in PPARγ expression, resulting in adipogenesis inhibition. However, Grail overexpression induced the same effects. Grail was shown to interact with PPARγ, targeting it for degradation and modulating its adipogenic activity. PPARγ expression was shown to be considerably reduced in Grail knockout (KO) mice fed normal diet or high-fat diet (HFD). The administration of both normal diet or HFD to Grail KO mice led to lower adipose mass and body weight than those in the wild-type mice. HFD-fed Grail KO mice had improved glucose and insulin tolerance. Taken together, our results indicate that Grail plays a pivotal role in adipogenesis and diet-induced obesity by regulating PPARγ activity.
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Affiliation(s)
- Peiyao Liu
- Department of Physiology & Biophysics, National Defense Medical Center, Taipei, Taiwan, 114, Republic of China
| | - Poshiuan Hsieh
- Department of Physiology & Biophysics, National Defense Medical Center, Taipei, Taiwan, 114, Republic of China.,Institute of Preventive Medicine, National Defense Medical Center, New Taipei City, Taiwan, 114, Republic of China
| | - Huitsu Lin
- Institute of Preventive Medicine, National Defense Medical Center, New Taipei City, Taiwan, 114, Republic of China
| | - Tejung Liu
- Department of Physical Medicine and Rehabilitation, Tri-Service General Hospital, Taipei, Taiwan, 114, Republic of China.,Department of Physical Medicine and Rehabilitation, School of Medicine, National Defense Medical Center, Taipei, Taiwan, 114, Republic of China.,Department of Physical Medicine and Rehabilitation, Taoyuan Armed Force General Hospital, Taoyuan, Taiwan, 114, Republic of China
| | - Hsuehling Wu
- Institute of Preventive Medicine, National Defense Medical Center, New Taipei City, Taiwan, 114, Republic of China
| | - Chengcheung Chen
- Institute of Preventive Medicine, National Defense Medical Center, New Taipei City, Taiwan, 114, Republic of China
| | - Yingchuan Chen
- Institute of Preventive Medicine, National Defense Medical Center, New Taipei City, Taiwan, 114, Republic of China.
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9
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Zhang J, Lei Z, Huang Z, Zhang X, Zhou Y, Luo Z, Zeng W, Su J, Peng C, Chen X. Epigallocatechin-3-gallate(EGCG) suppresses melanoma cell growth and metastasis by targeting TRAF6 activity. Oncotarget 2018; 7:79557-79571. [PMID: 27791197 PMCID: PMC5346735 DOI: 10.18632/oncotarget.12836] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 10/07/2016] [Indexed: 11/30/2022] Open
Abstract
TRAF6 (TNF Receptor-Associated Factor 6) is an E3 ubiquitin ligase that contains a Ring domain, induces K63-linked polyubiquitination, and plays a critical role in signaling transduction. Our previous results demonstrated that TRAF6 is overexpressed in melanoma and that TRAF6 knockdown dramatically attenuates tumor cell growth and metastasis. In this study, we found that EGCG can directly bind to TRAF6, and a computational model of the interaction between EGCG and TRAF6 revealed that EGCG probably interacts with TRAF6 at the residues of Gln54, Gly55, Asp57 ILe72, Cys73 and Lys96. Among these amino acids, mutation of Gln54, Asp57, ILe72 in TRAF6 could destroy EGCG bound to TRAF6, furthermore, our results demonstrated that EGCG significantly attenuates interaction between TRAF6 and UBC13(E2) and suppresses TRAF6 E3 ubiquitin ligase activity in vivo and in vitro. Additionally, the phosphorylation of IκBα, p-TAK1 expression are decreased and the nuclear translocation of p65 and p50 is blocked by treatment with EGCG, leading to inactivation of the NF-κB pathway. Moreover, EGCG significantly inhibits cell growth as well as the migration and invasion of melanoma cells. Taken together, these findings show that EGCG is a novel E3 ubiquitin ligase inhibitor that could be used to target TRAF6 for chemotherapy or the prevention of melanoma.
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Affiliation(s)
- Jianglin Zhang
- The Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Zhou Lei
- The Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Zunnan Huang
- Key Laboratory for Medical Molecular Diagnostics of Guangdong Province, Dongguan Scientific Research Center, Guangdong Medical University, Dongguan, Guangdong, China
| | - Xu Zhang
- The Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Youyou Zhou
- The Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Zhongling Luo
- The Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Weiqi Zeng
- The Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Juan Su
- The Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Cong Peng
- The Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Xiang Chen
- The Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Xiangya Hospital, Central South University, Changsha, Hunan, China
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Ebner P, Versteeg GA, Ikeda F. Ubiquitin enzymes in the regulation of immune responses. Crit Rev Biochem Mol Biol 2017; 52:425-460. [PMID: 28524749 PMCID: PMC5490640 DOI: 10.1080/10409238.2017.1325829] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 04/06/2017] [Accepted: 04/28/2017] [Indexed: 12/25/2022]
Abstract
Ubiquitination plays a central role in the regulation of various biological functions including immune responses. Ubiquitination is induced by a cascade of enzymatic reactions by E1 ubiquitin activating enzyme, E2 ubiquitin conjugating enzyme, and E3 ubiquitin ligase, and reversed by deubiquitinases. Depending on the enzymes, specific linkage types of ubiquitin chains are generated or hydrolyzed. Because different linkage types of ubiquitin chains control the fate of the substrate, understanding the regulatory mechanisms of ubiquitin enzymes is central. In this review, we highlight the most recent knowledge of ubiquitination in the immune signaling cascades including the T cell and B cell signaling cascades as well as the TNF signaling cascade regulated by various ubiquitin enzymes. Furthermore, we highlight the TRIM ubiquitin ligase family as one of the examples of critical E3 ubiquitin ligases in the regulation of immune responses.
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Abstract
Rho GTPases regulate cytoskeletal and cell adhesion dynamics and thereby coordinate a wide range of cellular processes, including cell migration, cell polarity and cell cycle progression. Most Rho GTPases cycle between a GTP-bound active conformation and a GDP-bound inactive conformation to regulate their ability to activate effector proteins and to elicit cellular responses. However, it has become apparent that Rho GTPases are regulated by post-translational modifications and the formation of specific protein complexes, in addition to GTP-GDP cycling. The canonical regulators of Rho GTPases - guanine nucleotide exchange factors, GTPase-activating proteins and guanine nucleotide dissociation inhibitors - are regulated similarly, creating a complex network of interactions to determine the precise spatiotemporal activation of Rho GTPases.
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Affiliation(s)
- Richard G Hodge
- Randall Division of Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, UK
| | - Anne J Ridley
- Randall Division of Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, UK
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12
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Ramiscal RR, Parish IA, Lee-Young RS, Babon JJ, Blagih J, Pratama A, Martin J, Hawley N, Cappello JY, Nieto PF, Ellyard JI, Kershaw NJ, Sweet RA, Goodnow CC, Jones RG, Febbraio MA, Vinuesa CG, Athanasopoulos V. Attenuation of AMPK signaling by ROQUIN promotes T follicular helper cell formation. eLife 2015; 4. [PMID: 26496200 PMCID: PMC4716841 DOI: 10.7554/elife.08698] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 10/22/2015] [Indexed: 12/11/2022] Open
Abstract
T follicular helper cells (Tfh) are critical for the longevity and quality of antibody-mediated protection against infection. Yet few signaling pathways have been identified to be unique solely to Tfh development. ROQUIN is a post-transcriptional repressor of T cells, acting through its ROQ domain to destabilize mRNA targets important for Th1, Th17, and Tfh biology. Here, we report that ROQUIN has a paradoxical function on Tfh differentiation mediated by its RING domain: mice with a T cell-specific deletion of the ROQUIN RING domain have unchanged Th1, Th2, Th17, and Tregs during a T-dependent response but show a profoundly defective antigen-specific Tfh compartment. ROQUIN RING signaling directly antagonized the catalytic α1 subunit of adenosine monophosphate-activated protein kinase (AMPK), a central stress-responsive regulator of cellular metabolism and mTOR signaling, which is known to facilitate T-dependent humoral immunity. We therefore unexpectedly uncover a ROQUIN–AMPK metabolic signaling nexus essential for selectively promoting Tfh responses. DOI:http://dx.doi.org/10.7554/eLife.08698.001 The immune system protects the body from invading microbes like bacteria and viruses. Upon recognizing the presence of these microbes, cells in the immune system are activated to destroy the foreign threat and clear it from the body. A type of immune cell called T follicular helper cells (or Tfh for short) are formed during an infection and are essential for coordinating other immune cells to produce high-quality antibody proteins that attack the microbes. Without Tfh cells, life-long production of these protective antibodies is severely crippled, which can cause common variable immune deficiency and other serious immunodeficiency diseases. On the other hand, the body must also avoid generating excessive numbers of Tfh cells, which can lead to the production of antibodies that attack healthy cells of the body. ROQUIN is a protein that inhibits the formation of Tfh cells and other types of active T cells. A region on the protein called the ROQ domain destabilizes particular molecules of ribonucleic acid (RNA) that are required for these specialist T cells to form and work properly. ROQUIN belongs to a large family of enzymes that have a so-called RING domain, which is a feature that enables these enzymes to attach tags onto specific target proteins to modify their activity or stability. However, it was not known whether the RING domain of ROQUIN was active. Ramiscal et al. now address this question in mice. Unexpectedly, the experiments show that the RING domain is required to promote the formation of Tfh cells, but not other types of active T cells. This domain allows ROQUIN to repress an enzyme called AMPK, which normally blocks cell growth by regulating cell metabolism. The findings suggest that the different roles of the ROQ and RING domains allow ROQUIN to fine-tune the numbers of Tfh cells so that they remain within a safe range. In the future, these findings may aid the development of vaccines that are more efficient at generating protective Tfh cells to prevent infectious diseases. DOI:http://dx.doi.org/10.7554/eLife.08698.002
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Affiliation(s)
- Roybel R Ramiscal
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Ian A Parish
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Robert S Lee-Young
- Cellular and Molecular Metabolism Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Australia
| | - Jeffrey J Babon
- Division of Structural Biology, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Julianna Blagih
- Department of Physiology, Goodman Cancer Research Centre, McGill University, Montreal, Canada
| | - Alvin Pratama
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Jaime Martin
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Naomi Hawley
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Jean Y Cappello
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Pablo F Nieto
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Julia I Ellyard
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Nadia J Kershaw
- Division of Structural Biology, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Rebecca A Sweet
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Christopher C Goodnow
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, Australian National University, Canberra, Australia.,Immunology Division, Garvan Institute of Medical Research, Sydney, Australia
| | - Russell G Jones
- Department of Physiology, Goodman Cancer Research Centre, McGill University, Montreal, Canada
| | - Mark A Febbraio
- Cellular and Molecular Metabolism Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Australia.,Diabetes and Metabolism Division, Garvan Institute of Medical Research, Sydney, Australia
| | - Carola G Vinuesa
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Vicki Athanasopoulos
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, Australian National University, Canberra, Australia
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Weil R. Does antigen masking by ubiquitin chains protect from the development of autoimmune diseases? Front Immunol 2014; 5:262. [PMID: 24917867 PMCID: PMC4042494 DOI: 10.3389/fimmu.2014.00262] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 05/19/2014] [Indexed: 11/20/2022] Open
Abstract
Autoimmune diseases are characterized by the production of antibodies against self-antigens and generally arise from a failure of central or peripheral tolerance. However, these diseases may develop when newly appearing antigens are not recognized as self by the immune system. The mechanism by which some antigens are “invisible” to the immune system is not completely understood. Apoptotic and complement system defects or autophagy imbalance can generate this antigenic autoreactivity. Under particular circumstances, cellular debris containing autoreactive antigens can be recognized by innate immune receptors or other sensors and can eventually lead to autoimmunity. Ubiquitination may be one of the mechanisms protecting autoreactive antigens from the immune system that, if disrupted, can lead to autoimmunity. Ubiquitination is an essential post-translational modification used by cells to target proteins for degradation or to regulate other intracellular processes. The level of ubiquitination is regulated during T cell tolerance and apoptosis and E3 ligases have emerged as a crucial signaling pathway for the regulation of T cell tolerance toward self-antigens. I propose here that an unrecognized role of ubiquitin and ubiquitin-like proteins could be to render intracellular or foreign antigens (present in cellular debris resulting from apoptosis, complement system, or autophagy defects) invisible to the immune system in order to prevent the development of autoimmunity.
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Affiliation(s)
- Robert Weil
- Unité de Signalisation Moléculaire et Activation Cellulaire, CNRS URA 2582, Institut Pasteur , Paris , France
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14
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Enesa K, Evans P. The Biology of A20-Like Molecules. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 809:33-48. [DOI: 10.1007/978-1-4939-0398-6_3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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15
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Abstract
T cells are the master regulators of adaptive immune responses and maintenance of their tolerance is critical to prevent autoimmunity. However, in the case of carcinogenesis, the tumor microenvironment aids T-cell tolerance, which contributes to uncontrolled tumor growth. Recently, there has been significant progress in understanding the intrinsic extracellular (positive and negative costimulatory molecules on APCs) and intracellular mechanisms (E3 ubiquitin ligases, transcriptional and epigenetic repressors), as well as extrinsic mechanisms (Tregs and tolerogenic dendritic cells) that are required for the implementation and maintenance of T-cell tolerance. Ultimately, understanding and manipulating T-cell tolerance will help to break the tolerance state in cancer.
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Affiliation(s)
- Roza Nurieva
- Department of Immunology & Center for Inflammation & Cancer, MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Junmei Wang
- Department of Immunology & Center for Inflammation & Cancer, MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Anupama Sahoo
- Department of Immunology & Center for Inflammation & Cancer, MD Anderson Cancer Center, Houston, TX 77030, USA
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16
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Abstract
One of the mechanisms that are in place to control the activation of mature T cells that bear self-reactive antigen receptors is anergy, a long-term state of hyporesponsiveness that is established in T cells in response to suboptimal stimulation. T cells receive signals that result not only from antigen recognition and costimulation but also from other sources, including cytokine receptors, inhibitory receptors or metabolic sensors. Integration of those signals will determine T cell fate. Under conditions that induce anergy, T cells activate a program of gene expression that leads to the production of proteins that block T cell receptor signaling and inhibit cytokine gene expression. In this review we will examine those signals that determine functional outcome following antigen encounter, review current knowledge of the factors that ensure signaling inhibition and epigenetic gene silencing in anergic cells and explore the mechanisms that lead to the reversal of anergy and the reacquisition of effector functions.
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Affiliation(s)
- Rut Valdor
- Department of Pathology. Albert Einstein College of Medicine. Bronx, NY. USA
| | - Fernando Macian
- Department of Pathology. Albert Einstein College of Medicine. Bronx, NY. USA
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17
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Troeger A, Chae HD, Senturk M, Wood J, Williams DA. A unique carboxyl-terminal insert domain in the hematopoietic-specific, GTPase-deficient Rho GTPase RhoH regulates post-translational processing. J Biol Chem 2013; 288:36451-62. [PMID: 24189071 DOI: 10.1074/jbc.m113.505727] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
RhoH is a hematopoietic-specific, GTPase-deficient member of the Rho GTPase family that was first identified as a hypermutable gene in human B lineage lymphomas. RhoH remains in a constitutively active state and thus its effects are regulated by expression levels or post-translational modifications. Similar to other small GTPases, intracellular localization of RhoH is dependent upon the conserved "CAAX" box and surrounding sequences within the carboxyl (C) terminus. However, RhoH also contains a unique C-terminal "insert" domain of yet undetermined function. RhoH serves as adaptor molecule in T cell receptor signaling and RhoH expression correlates with the unfavorable prognostic marker ZAP70 in human chronic lymphocytic leukemia. Disease progression is attenuated in a Rhoh(-/-) mouse model of chronic lymphocytic leukemia and treatment of primary human chronic lymphocytic leukemia cells with Lenalidomide results in reduced RhoH protein levels. Thus, RhoH is a potential therapeutic target in B cell malignancies. In the current studies, we demonstrate that deletion of the insert domain (LFSINE) results in significant cytoplasmic protein accumulation. Using inhibitors of degradation pathways, we show that LFSINE regulates lysosomal RhoH uptake and degradation via chaperone-mediated autophagy. Whereas the C-terminal prenylation site is critical for ZAP70 interaction, subcellular localization and rescue of the Rhoh(-/-) T cell defect in vivo, the insert domain appears dispensable for these functions. Taken together, our findings suggest that the insert domain regulates protein stability and activity without otherwise affecting RhoH function.
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Affiliation(s)
- Anja Troeger
- From the Division of Hematology/Oncology, Boston Children's Hospital and the Dana-Farber Cancer Institute, Boston, Massachusetts 02115
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18
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Zhang Q, Li Y, Zhang L, Yang N, Meng J, Zuo P, Zhang Y, Chen J, Wang L, Gao X, Zhu D. E3 ubiquitin ligase RNF13 involves spatial learning and assembly of the SNARE complex. Cell Mol Life Sci 2013; 70:153-65. [PMID: 22890573 PMCID: PMC11113611 DOI: 10.1007/s00018-012-1103-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Revised: 07/01/2012] [Accepted: 07/19/2012] [Indexed: 11/26/2022]
Abstract
Changes in the structure and number of synapses modulate learning, memory and cognitive disorders. Ubiquitin-mediated protein modification is a key mechanism for regulating synaptic activity, though the precise control of this process remains poorly understood. RING finger protein 13 (RNF13) is a recently identified E3 ubiquitin ligase, and its in vivo function remains completely unknown. We show here that genetic deletion of RNF13 in mice leads to a significant deficit in spatial learning as determined by the Morris water maze test and Y-maze learning test. At the ultrastructral level, the synaptic vesicle density was decreased and the area of the active zone was increased at hippocampal synapses of RNF13-null mice compared with those of wild-type littermates. We found no change in the levels of SNARE (soluble N-ethylmaleimide-sensitive factor-attachment protein receptor) complex proteins in the hippocampus of RNF13-null mice, but impaired SNARE complex assembly. RNF13 directly interacted with snapin, a SNAP-25-interacting protein. Interestingly, snapin was ubiquitinated by RNF13 via the lysine-29 conjugated polyubiquitin chain, which in turn promoted the association of snapin with SNAP-25. Consistently, we found an attenuated interaction between snapin and SNAP-25 in the RNF13-null mice. Therefore, these results suggest that RNF13 is involved in the regulation of the SNARE complex, which thereby controls synaptic function.
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Affiliation(s)
- Qiang Zhang
- Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Tsinghua University, Beijing, 100005 China
| | - Yanfeng Li
- Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Tsinghua University, Beijing, 100005 China
| | - Lei Zhang
- Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Tsinghua University, Beijing, 100005 China
| | - Nan Yang
- Department of Pharmacology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Tsinghua University, Beijing, 100005 China
| | - Jiao Meng
- Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Tsinghua University, Beijing, 100005 China
| | - Pingping Zuo
- Department of Pharmacology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Tsinghua University, Beijing, 100005 China
| | - Yong Zhang
- Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Tsinghua University, Beijing, 100005 China
| | - Jie Chen
- Department of Pathology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Tsinghua University, Beijing, 100730 China
| | - Li Wang
- Department of Epidemiology and Biostatistics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Tsinghua University, Beijing, 100005 China
| | - Xiang Gao
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Research, Nanjing University, Nanjing, 210061 China
| | - Dahai Zhu
- Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Tsinghua University, Beijing, 100005 China
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19
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Gholizadeh A. Comparative fusion expression of maize SINAT5 in two different strains of Escherichia coli. GENETICS AND MOLECULAR RESEARCH 2012; 11:2760-8. [PMID: 23007971 DOI: 10.4238/2012.august.24.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
SINAT5 is a plant E3 ligase that regulates auxin signaling and root morphogenesis by ubiquitination of the NAC1 protein. Consequently, it may be a putative regulator of aspects of plant development cycles that are controlled by auxin. Efficient production, purification and correctly folded form of this protein are important requirements for functional studies. We produced and quantitatively compared fusion expression of the "maltose binding protein (mbp)-maize sinat5" construct in two different strains of Escherichia coli. One-step purification of fused products gave about 33 mg protein/L bacterial cell culture for E. coli TB1 cells and approximately 18 mg protein/L bacterial cell culture for E. coli DH5α cells. Continuous expression of the fused product and similarity of growth patterns were observed in both cultures.
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Affiliation(s)
- A Gholizadeh
- Department of Molecular Biotechnology, Research Institute for Fundamental Sciences, University of Tabriz, Tabriz, Iran.
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20
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Ortiz YM, García LF, Álvarez CM. Differences in phosphorylation patterns of intracellular signaling proteins in T cells from kidney transplant patients with different outcomes. Clin Transplant 2012; 26:935-48. [PMID: 22774864 DOI: 10.1111/j.1399-0012.2012.01683.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/24/2012] [Indexed: 11/26/2022]
Abstract
Transplant patients with long-term graft survival (LTS) may have developed mechanisms that prevent rejection and allow graft function under low or no immunosuppressive therapy. In murine models, T cell tolerance is associated with alterations in the expression/activation of proteins involved in T cell signaling. These alterations have not been reported in transplanted patients with different outcomes. This study aimed to evaluate calcium mobilization, the phosphorylation of different proteins involved in T cell signaling and the expression of molecules associated with anergy, in T cells from kidney transplant patients. No differences were observed in calcium mobilization, although transplanted patients had a tendency toward augmented calcium flux. Chronic rejection patients (ChrRx) displayed lower Lck basal phosphorylation levels compared with LTS patients, and the phosphorylation profile of proteins evaluated was different. Among the groups, phosphorylation of Zap-70 was higher in LTS patients compared with ChrRx, and LAT phosphorylation was lower in LTS and ChrRx patients compared with healthy controls. The expression of molecules related to the anergic phenotype was similar among the study groups. Results suggest that phosphorylation patterns, rather than phosphorylation levels, may correlate with transplant outcome and that anergy may not be the main mechanism mediating LTS.
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Affiliation(s)
- Yaneth M Ortiz
- Laboratorio de Inmunología de Trasplantes, Grupo de Inmunología Celular e Inmunogenética, Instituto de Investigaciones Médicas, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
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21
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Nakamura N. The Role of the Transmembrane RING Finger Proteins in Cellular and Organelle Function. MEMBRANES 2011; 1:354-93. [PMID: 24957874 PMCID: PMC4021871 DOI: 10.3390/membranes1040354] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 11/24/2011] [Accepted: 12/05/2011] [Indexed: 01/08/2023]
Abstract
A large number of RING finger (RNF) proteins are present in eukaryotic cells and the majority of them are believed to act as E3 ubiquitin ligases. In humans, 49 RNF proteins are predicted to contain transmembrane domains, several of which are specifically localized to membrane compartments in the secretory and endocytic pathways, as well as to mitochondria and peroxisomes. They are thought to be molecular regulators of the organization and integrity of the functions and dynamic architecture of cellular membrane and membranous organelles. Emerging evidence has suggested that transmembrane RNF proteins control the stability, trafficking and activity of proteins that are involved in many aspects of cellular and physiological processes. This review summarizes the current knowledge of mammalian transmembrane RNF proteins, focusing on their roles and significance.
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Affiliation(s)
- Nobuhiro Nakamura
- Department of Biological Sciences, Tokyo Institute of Technology, 4259-B13 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.
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22
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Synthetic biology approach to reconstituting the ubiquitylation cascade in bacteria. EMBO J 2011; 31:378-90. [PMID: 22081111 DOI: 10.1038/emboj.2011.397] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Accepted: 10/07/2011] [Indexed: 12/16/2022] Open
Abstract
Covalent modification of proteins with ubiquitin (Ub) is widely implicated in the control of protein function and fate. Over 100 deubiquitylating enzymes rapidly reverse this modification, posing challenges to the biochemical and biophysical characterization of ubiquitylated proteins. We circumvented this limitation with a synthetic biology approach of reconstructing the entire eukaryotic Ub cascade in bacteria. Co-expression of affinity-tagged substrates and Ub with E1, E2 and E3 enzymes allows efficient purification of ubiquitylated proteins in milligram quantity. Contrary to in-vitro assays that lead to spurious modification of several lysine residues of Rpn10 (regulatory proteasomal non-ATPase subunit), the reconstituted system faithfully recapitulates its monoubiquitylation on lysine 84 that is observed in vivo. Mass spectrometry revealed the ubiquitylation sites on the Mind bomb E3 ligase and the Ub receptors Rpn10 and Vps9. Förster resonance energy transfer (FRET) analyses of ubiquitylated Vps9 purified from bacteria revealed that although ubiquitylation occurs on the Vps9-GEF domain, it does not affect the guanine nucleotide exchanging factor (GEF) activity in vitro. Finally, we demonstrated that ubiquitylated Vps9 assumes a closed structure, which blocks additional Ub binding. Characterization of several ubiquitylated proteins demonstrated the integrity, specificity and fidelity of the system, and revealed new biological findings.
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23
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Ichikawa D, Mizuno M, Yamamura T, Miyake S. GRAIL (gene related to anergy in lymphocytes) regulates cytoskeletal reorganization through ubiquitination and degradation of Arp2/3 subunit 5 and coronin 1A. J Biol Chem 2011; 286:43465-74. [PMID: 22016387 DOI: 10.1074/jbc.m111.222711] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Anergy is an important mechanism for the maintenance of peripheral tolerance and avoidance of autoimmunity. The up-regulation of E3 ubiqitin ligases, including GRAIL (gene related to anergy in lymphocytes), is a key event in the induction and preservation of anergy in T cells. However, the mechanisms of GRAIL-mediated anergy induction are still not completely understood. We examined which proteins serve as substrates for GRAIL in anergic T cells. Arp2/3-5 (actin-related protein 2/3 subunit 5) and coronin 1A were polyubiquitinated by GRAIL via Lys-48 and Lys-63 linkages. In anergic T cells and GRAIL-overexpressed T cells, the expression of Arp2/3-5 and coronin 1A was reduced. Furthermore, we demonstrated that GRAIL impaired lamellipodium formation and reduced the accumulation of F-actin at the immunological synapse. GRAIL functions via the ubiquitination and degradation of actin cytoskeleton-associated proteins, in particular Arp2/3-5 and coronin 1A. These data reveal that GRAIL regulates proteins involved in the actin cytoskeletal organization, thereby maintaining the unresponsive state of anergic T cells.
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Affiliation(s)
- Daiju Ichikawa
- Department of Immunology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashi, Kodaira, Tokyo 187-8502, Japan
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24
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Abstract
CD4(+) T cells are the master regulators of adaptive immune responses, and many autoimmune diseases arise due to a breakdown of self-tolerance in CD4(+) T cells. Activation of CD4(+) T cells is regulated by not only the binding of peptide-major histocompatibility complexes to T-cell receptor but also costimulatory signals from antigen-presenting cells. Recently, there has been progress in understanding the extracellular and intracellular mechanisms that are required for implementation and maintenance of T-cell tolerance. Understanding of the molecular mechanisms underlying T-cell tolerance will lead to development of pharmacological approaches either to promote the tolerance state in terms of autoimmunity or to break tolerance in cancer.
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Affiliation(s)
- Roza I Nurieva
- Department of Immunology and Center for Inflammation and Cancer, MD Anderson Cancer Center, Houston, TX 77030, USA
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25
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Egeler EL, Urner LM, Rakhit R, Liu CW, Wandless TJ. Ligand-switchable substrates for a ubiquitin-proteasome system. J Biol Chem 2011; 286:31328-36. [PMID: 21768107 DOI: 10.1074/jbc.m111.264101] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cellular maintenance of protein homeostasis is essential for normal cellular function. The ubiquitin-proteasome system (UPS) plays a central role in processing cellular proteins destined for degradation, but little is currently known about how misfolded cytosolic proteins are recognized by protein quality control machinery and targeted to the UPS for degradation in mammalian cells. Destabilizing domains (DDs) are small protein domains that are unstable and degraded in the absence of ligand, but whose stability is rescued by binding to a high affinity cell-permeable ligand. In the work presented here, we investigate the biophysical properties and cellular fates of a panel of FKBP12 mutants displaying a range of stabilities when expressed in mammalian cells. Our findings correlate observed cellular instability to both the propensity of the protein domain to unfold in vitro and the extent of ubiquitination of the protein in the non-permissive (ligand-free) state. We propose a model in which removal of stabilizing ligand causes the DD to unfold and be rapidly ubiquitinated by the UPS for degradation at the proteasome. The conditional nature of DD stability allows a rapid and non-perturbing switch from stable protein to unstable UPS substrate unlike other methods currently used to interrogate protein quality control, providing tunable control of degradation rates.
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Affiliation(s)
- Emily L Egeler
- Department of Chemical and Systems Biology, Stanford University, Stanford, California 94305, USA
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26
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de la Vega M, Burrows JF, Johnston JA. Ubiquitination: Added complexity in Ras and Rho family GTPase function. Small GTPases 2011; 2:192-201. [PMID: 22145091 DOI: 10.4161/sgtp.2.4.16707] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 07/08/2011] [Accepted: 07/08/2011] [Indexed: 12/17/2022] Open
Abstract
The regulation of the small GTPases leading to their membrane localization has long been attributed to processing of their C-terminal CAAX box. As deregulation of many of these GTPases have been implicated in cancer and other disorders, prenylation and methylation of this CAAX box has been studied in depth as a possibility for drug targeting, but unfortunately, to date no drug has proved clinically beneficial. However, these GTPases also undergo other modifications that may be important for their regulation. Ubiquitination has long been demonstrated to regulate the fate of numerous cellular proteins and recently it has become apparent that many GTPases, along with their GAPs, GeFs and GDis, undergo ubiquitination leading to a variety of fates such as re-localization or degradation. in this review we focus on the recent literature demonstrating that the regulation of small GTPases by ubiquitination, either directly or indirectly, plays a considerable role in controlling their function and that targeting these modifications could be important for disease treatment.
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Affiliation(s)
- Michelle de la Vega
- Centre for Infection and Immunity; School of Medicine, Dentistry and Biomedical Sciences; Queen's University; Belfast, UK
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27
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Mechanisms that regulate peripheral immune responses to control organ-specific autoimmunity. Clin Dev Immunol 2011; 2011:294968. [PMID: 21603204 PMCID: PMC3095406 DOI: 10.1155/2011/294968] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2011] [Accepted: 02/16/2011] [Indexed: 01/10/2023]
Abstract
The immune system must balance the need to maintain a diverse repertoire of lymphocytes to be able to fight infection with the need to maintain tolerance to self-proteins. The immune system places strict regulation over the ability of T cells to produce the major T cell growth factor interleukin 2 as this cytokine can influence a variety of immune outcomes. T cells require the delivery of two signals, one through the antigen receptor and a second through the costimulatory receptor CD28. The immune system uses a variety of E3 ubiquitin ligases to target signaling proteins that function downstream of the TCR and CD28 receptors. Mutations in these E3 ligases can lead to a breakdown in immune tolerance and development of autoimmunity. This paper will examine the role of a range of E3 ubiquitin ligases and signaling pathways that influence the development of T-cell effector responses and the development of organ-specific autoimmune diseases such as type 1 diabetes.
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28
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Paolino M, Thien CBF, Gruber T, Hinterleitner R, Baier G, Langdon WY, Penninger JM. Essential role of E3 ubiquitin ligase activity in Cbl-b-regulated T cell functions. THE JOURNAL OF IMMUNOLOGY 2011; 186:2138-47. [PMID: 21248250 DOI: 10.4049/jimmunol.1003390] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
E3 ubiquitin ligases have been placed among the essential molecules involved in the regulation of T cell functions and T cell tolerance. However, it has never been experimentally proven in vivo whether these functions indeed depend on the catalytic E3 ligase activity. The Casitas B-cell lymphoma (Cbl) family protein Cbl-b was the first E3 ubiquitin ligase directly implicated in the activation and tolerance of the peripheral T cell. In this study, we report that selective genetic inactivation of Cbl-b E3 ligase activity phenocopies the T cell responses observed when total Cbl-b is ablated, resulting in T cell hyperactivation, spontaneous autoimmunity, and impaired induction of T cell anergy in vivo. Moreover, mice carrying a Cbl-b E3 ligase-defective mutation spontaneously reject tumor cells that express human papilloma virus Ags. These data demonstrate for the first time, to our knowledge, that the catalytic function of an E3 ligase, Cbl-b, is essential for negative regulation of T cells in vivo. Thus, modulation of the E3 ligase activity of Cbl-b might be a novel modality to control T cell immunity in vaccination, cancer biology, or autoimmunity.
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Affiliation(s)
- Magdalena Paolino
- Institute of Molecular Biotechnology of the Austrian Academy of Science, A-1030 Vienna, Austria
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29
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Fiol DF, Sanmarti E, Lim AH, Kültz D. A novel GRAIL E3 ubiquitin ligase promotes environmental salinity tolerance in euryhaline tilapia. Biochim Biophys Acta Gen Subj 2010; 1810:439-45. [PMID: 21126558 DOI: 10.1016/j.bbagen.2010.11.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2010] [Revised: 11/14/2010] [Accepted: 11/17/2010] [Indexed: 11/24/2022]
Abstract
BACKGROUND Tilapia (Oreochromis mossambicus) are euryhaline fishes capable of tolerating large salinity changes. In a previous study aimed to identify genes involved in osmotolerance, we isolated an mRNA sequence with similarity to GRAIL (Gene Related to Anergy In Lymphocytes), which is a critical regulator of adaptive immunity and development. Tilapia GRAIL contains a PA (protease associated) domain and a C3H2C3 RING finger domain indicative of E3 ubiquitin ligase activity. SCOPE OF REVIEW Western blots analysis was used to assess GRAIL expression pattern and responses to hyperosmotic stress. Immunohistochemistry was used to reveal the cellular localization of GRAIL in gill epithelium. Overexpression in HEK293 T-Rex cells was used to functionally characterize tilapia GRAIL. Salinity stress causes strong up-regulation of both mRNA and protein levels of tilapia GRAIL in gill epithelium. Tissue distribution of GRAIL protein is mainly confined to gill epithelium, which is the primary tissue responsible for osmoregulation of teleost fishes. Overexpression of tilapia GRAIL in HEK293 cells increases cell survival (cell viability) while decreases apoptosis during salinity challenge. MAJOR CONCLUSIONS Our data indicate that tilapia GRAIL is a novel E3 ubiquitin ligase involved in osmotic stress signaling, which promotes environmental salinity tolerance by supporting gill cell function during hyperosmotic stress. GENERAL SIGNIFICANCE Involvement of tilapia GRAIL in the osmotic stress response suggests that GRAIL E3 ubiquitin ligases play a broader role in environmental stress responses, beyond their documented functions in adaptive immunity and development.
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Affiliation(s)
- Diego F Fiol
- Physiological Genomics Group, Department of Animal Sciences, University of California at Davis, CA 95616, USA
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30
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Whiting CC, Su LL, Lin JT, Fathman CG. GRAIL: a unique mediator of CD4 T-lymphocyte unresponsiveness. FEBS J 2010; 278:47-58. [PMID: 21078124 DOI: 10.1111/j.1742-4658.2010.07922.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
GRAIL (gene related to anergy in lymphocytes, also known as RNF128), an ubiquitin-protein ligase (E3), utilizes a unique single transmembrane protein with a split-function motif, and is an important gatekeeper of T-cell unresponsiveness. Although it may play a role in other CD4 T-cell functions including activation, survival and differentiation, GRAIL is most well characterized as a negative regulator of T-cell receptor responsiveness and cytokine production. Here, we review the recent literature on this remarkable E3 in the regulation of human and mouse CD4 T-cell unresponsiveness.
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Affiliation(s)
- Chan C Whiting
- Department of Medicine, Stanford University, Stanford, CA 94305, USA
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31
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Jin X, Cheng H, Chen J, Zhu D. RNF13: an emerging RING finger ubiquitin ligase important in cell proliferation. FEBS J 2010; 278:78-84. [PMID: 21078127 DOI: 10.1111/j.1742-4658.2010.07925.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Protein ubiquitination mediated by ubiquitin ligases plays a very important role in a wide spectrum of biological processes including development and disease pathogenesis. RING finger protein 13 (RNF13) is a recently identified ubiquitin ligase which contains an N-terminal protease-associated domain and a C-terminal RING finger domain separated by a transmembrane region. RNF13 is an evolutionarily conserved protein. Most interestingly, RNF13 expression is developmentally regulated during myogenesis and is upregulated in various human tumors. These data suggest that RNF13, acting as an ubiquitin ligase, might have profound biological functions during development and disease. This minireview summarizes recent work on RNF13 functions related to cell proliferation, differentiation and cancer development.
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Affiliation(s)
- Xianglan Jin
- National Laboratory of Medical Molecular Biology, Tsinghua University, Beijing, China
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Nurieva RI, Zheng S, Jin W, Chung Y, Zhang Y, Martinez GJ, Reynolds JM, Wang SL, Lin X, Sun SC, Lozano G, Dong C. The E3 ubiquitin ligase GRAIL regulates T cell tolerance and regulatory T cell function by mediating T cell receptor-CD3 degradation. Immunity 2010; 32:670-80. [PMID: 20493730 DOI: 10.1016/j.immuni.2010.05.002] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Revised: 02/11/2010] [Accepted: 03/31/2010] [Indexed: 01/26/2023]
Abstract
T cell activation is tightly regulated to avoid autoimmunity. Gene related to anergy in lymphocytes (GRAIL, encoded by Rnf128) is an E3 ubiquitin ligase associated with T cell tolerance. Here, we generated and analyzed GRAIL-deficient mice and found they were resistant to immune tolerance induction and exhibited greater susceptibility to autoimmune diseases than wild-type mice. GRAIL-deficient naive T cells, after activation, exhibited increased proliferation and cytokine expression than controls and did not depend on costimulation for effector generation. Moreover, GRAIL-deficient regulatory T (Treg) cells displayed reduced suppressive function, associated with increased Th17 cell-related gene expression. GRAIL-deficient naive and Treg cells were less efficient in downregulating T cell receptor (TCR)-CD3 expression after activation and exhibited increased NFATc1 transcription factor expression; GRAIL expression promoted CD3 ubiquitinylation. Our results indicate that GRAIL, by mediating TCR-CD3 degradation, regulates naive T cell tolerance induction and Treg cell function.
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Affiliation(s)
- Roza I Nurieva
- Department of Immunology, M.D. Anderson Cancer Center, Houston, TX 77030, USA.
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33
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Tseng TL, Lai WC, Jian T, Li C, Sun HFS, Way TD, Shieh JC. Affinity purification of Candida albicans CaCdc4-associated proteins reveals the presence of novel proteins involved in morphogenesis. Biochem Biophys Res Commun 2010; 395:152-7. [PMID: 20361932 DOI: 10.1016/j.bbrc.2010.03.162] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2010] [Accepted: 03/29/2010] [Indexed: 01/07/2023]
Abstract
Candida albicans CDC4 is nonessential and plays a role in suppressing filamentous growth, in contrast to its evolutionary counterparts involved in the G1-S transition of the cell cycle. Genetic epistasis analysis has indicated that proteins besides Sol1 are targets of C. albicans Cdc4. Moreover, no formal evidence suggests that C. albicans Cdc4 functions through the ubiquitin E3 ligase of the Skp1-Cul1/Cdc53-F-box complex. To elucidate the role of C. albicans CDC4, C. albicans Cdc4-associated proteins were sought by affinity purification. A 6xHis epitope-tagged C. albicans Cdc4 expressed from Escherichia coli was used in affinity purifications with the cell lysate of C. albicans cdc4 homozygous null mutant. Candida albicans Cdc4 and its associated proteins were resolved by SDS-PAGE and visualized by silver staining. The candidate proteins were recovered and trypsin-digested to generate MALDI-TOF spectra profiles, which were used to search against those of known proteins in the database to reveal their identities. Two out of four proteins encoded by GPH1 and THR1 genes were further verified to interact with C. albicans Cdc4 using a yeast two-hybrid assay. We conclude that in vitro affinity purification using C. albicans Cdc4 generated from E. coli as the bait and proteins from cell lysate of C. albicans cdc4 homozygous null mutant as a source of prey permit the identification of novel proteins that physically interact and functionally associate with C. albicans Cdc4.
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Affiliation(s)
- Tzu-Ling Tseng
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City, Taiwan, ROC
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34
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Bocock JP, Carmicle S, Madamba E, Erickson AH. Nuclear targeting of an endosomal E3 ubiquitin ligase. Traffic 2010; 11:756-66. [PMID: 20230530 DOI: 10.1111/j.1600-0854.2010.01060.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Ring finger protein 13 (RNF13) is an E3 ubiquitin ligase embedded in endosome membranes. The protein undergoes constitutive post-translational proteolysis, making its detection difficult unless cells are incubated with a proteasome inhibitor to allow biosynthetic forms to accumulate. When cells were treated with phorbol 12-myristate 13-acetate (PMA), RNF13 avoided proteolysis. A similar stabilization was seen on ionomycin treatment of cells. Drug treatment stabilized both the full-length protein and a membrane-embedded C-terminal fragment generated following ectodomain shedding. Immunofluorescence staining revealed that PMA treatment caused the protein to accumulate in recycling endosomes, where it colocalized with transferrin receptor, and on the inner nuclear membrane, where it colocalized with lamin B. Expression of dominant-negative Rab11 inhibited nuclear localization, suggesting RNF13 was targeted to the inner nuclear membrane through recycling endosomes. New protein synthesis was necessary for this targeting. Nuclear localization was confirmed by immunoelectron microscopy and by purification of the inner nuclear membrane. Stress-induced transport of an endosomal protein to the inner nuclear membrane is a novel mechanism for introduction of regulatory proteins to the DNA environment. RNF13, with its ubiquitin ligase-active RING domain, has the potential to turn over key nuclear proteins in response to signals received at the plasma membrane.
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Affiliation(s)
- Jeffrey P Bocock
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA
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35
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Schartner JM, Simonson WT, Wernimont SA, Nettenstrom LM, Huttenlocher A, Seroogy CM. Gene related to anergy in lymphocytes (GRAIL) expression in CD4+ T cells impairs actin cytoskeletal organization during T cell/antigen-presenting cell interactions. J Biol Chem 2009; 284:34674-81. [PMID: 19833735 PMCID: PMC2787330 DOI: 10.1074/jbc.m109.024497] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2009] [Revised: 09/30/2009] [Indexed: 11/06/2022] Open
Abstract
GRAIL (gene related to anergy in lymphocytes), is an E3 ubiquitin ligase with increased expression in anergic CD4+ T cells. The expression of GRAIL has been shown to be both necessary and sufficient for the induction of T cell (T) anergy. To date, several subsets of anergic T cells have demonstrated altered interactions with antigen-presenting cells (APC) and perturbed TCR-mediated signaling. The role of GRAIL in mediating these aspects of T cell anergy remains unclear. We used flow cytometry and confocal microscopy to examine T/APC interactions in GRAIL-expressing T cells. Increased GRAIL expression resulted in reduced T/APC conjugation efficiency as assessed by flow cytometry. Examination of single T/APC conjugates by confocal microscopy revealed altered polarization of polymerized actin and LFA-1 to the T/APC interface. When GRAIL expression was knocked down, actin polarization to the T/APC interface was restored, demonstrating that GRAIL is necessary for alteration of actin cytoskeletal rearrangement under anergizing conditions. Interestingly, proximal TCR signaling including calcium flux and phosphorylation of Vav were not disrupted by expression of GRAIL in CD4+ T cells. In contrast, interrogation of distal signaling events demonstrated significantly decreased JNK phosphorylation in GRAIL-expressing T cells. In sum, GRAIL expression in CD4+ T cells mediates alterations in the actin cytoskeleton during T/APC interactions. Moreover, in this model, our data dissociates proximal T cell signaling events from functional unresponsiveness. These data demonstrate a novel role for GRAIL in modulating T/APC interactions and provide further insight into the cell biology of anergic T cells.
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Affiliation(s)
- Jill M. Schartner
- From the Departments of Cellular and Molecular Pathology
- Pediatrics, Division of Allergy/Immunology/Rheumatology, University of Wisconsin, Madison, Wisconsin 53792
| | | | | | - Lauren M. Nettenstrom
- Pediatrics, Division of Allergy/Immunology/Rheumatology, University of Wisconsin, Madison, Wisconsin 53792
| | - Anna Huttenlocher
- Pediatrics, Division of Allergy/Immunology/Rheumatology, University of Wisconsin, Madison, Wisconsin 53792
| | - Christine M. Seroogy
- Pediatrics, Division of Allergy/Immunology/Rheumatology, University of Wisconsin, Madison, Wisconsin 53792
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36
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Baine I, Abe BT, Macian F. Regulation of T-cell tolerance by calcium/NFAT signaling. Immunol Rev 2009; 231:225-40. [PMID: 19754900 DOI: 10.1111/j.1600-065x.2009.00817.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Cells that escape negative selection in the thymus must be inactivated or eliminated in the periphery through a series of mechanisms that include the induction of anergy, dominant suppression by regulatory T cells, and peripheral deletion of self-reactive T cells. Calcium signaling plays a central role in the induction of anergy in T cells, which become functionally inactivated and incapable of proliferating and expressing cytokines following antigen re-encounter. Suboptimal stimulation of T cells results in the activation of a calcium/calcineurin/nuclear factor of activated T cells-dependent cell-intrinsic program of self-inactivation. The proteins encoded by those genes are required to impose a state of functional unresponsiveness through different mechanisms that include downregulation of T-cell receptor signaling and inhibition of cytokine transcription.
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Affiliation(s)
- Ian Baine
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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37
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E3 ubiquitin ligase GRAIL controls primary T cell activation and oral tolerance. Proc Natl Acad Sci U S A 2009; 106:16770-5. [PMID: 19805371 DOI: 10.1073/pnas.0908957106] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
T cell unresponsiveness or anergy is one of the mechanisms that maintain inactivity of self-reactive lymphocytes. E3 ubiquitin ligases are important mediators of the anergic state. The RING finger E3 ligase GRAIL is thought to selectively function in anergic T cells but its mechanism of action and its role in vivo are largely unknown. We show here that genetic deletion of Grail in mice leads not only to loss of an anergic phenotype in various models but also to hyperactivation of primary CD4(+) T cells. Grail(-/-) CD4(+) T cells hyperproliferate in vitro to TCR stimulation alone or with concomitant anti-CD28 costimulation, with transient increased survival. In vitro differentiated T helper 1 cells show slight but significant hypersecretion of IFN-gamma in Grail(-/-) mice whereas Th2 and Th17 cytokine secretions are unchanged. Consistent with defective in vitro anergy, oral tolerance is abolished in vivo in OT-II TCR transgenic Grail(-/-) mice fed with ovalbumin. In experimental allergic encephalitis, a model of organ-specific autoimmunity, oral tolerization with myelin basic protein was abrogated as well in Grail(-/-) mice. On the protein level, Grail(-/-) naïve T cells show no significant differences of total and phosphorylated levels of ZAP70, phospholipase Cgamma1, and MAP kinases p38 and JNK but elevated baseline levels of MAP kinase ERK1/2. In summary, we define a role for GRAIL in primary T cell activation, survival, and differentiation. In addition, we formally prove an indispensable role for GRAIL in T cell anergy and oral tolerance-a promising, antigen-specific strategy to treat autoimmune diseases.
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38
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39
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Su LL, Iwai H, Lin JT, Fathman CG. The transmembrane E3 ligase GRAIL ubiquitinates and degrades CD83 on CD4 T cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2009; 183:438-44. [PMID: 19542455 PMCID: PMC4300110 DOI: 10.4049/jimmunol.0900204] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Ubiquitination of eukaryotic proteins regulates a broad range of cellular processes, including T cell activation and tolerance. We have previously demonstrated that GRAIL (gene related to anergy in lymphocytes), a transmembrane RING finger ubiquitin E3 ligase, initially described as induced during the induction of CD4 T cell anergy, is also expressed in resting CD4 T cells. In this study, we show that GRAIL can down-modulate the expression of CD83 (previously described as a cell surface marker for mature dendritic cells) on CD4 T cells. GRAIL-mediated down-modulation of CD83 is dependent on an intact GRAIL extracellular protease-associated domain and an enzymatically active cytosolic RING domain, and proceeds via the ubiquitin-dependent 26S proteosome pathway. Ubiquitin modification of lysine residues K168 and K183, but not K192, in the cytoplasmic domain of CD83 was shown to be necessary for GRAIL-mediated degradation of CD83. Reduced CD83 surface expression levels were seen both on anergized CD4 T cells and following GRAIL expression by retroviral transduction, whereas GRAIL knock-down by RNA interference in CD4 T cells resulted in elevated CD83 levels. Furthermore, CD83 expression on CD4 T cells contributes to T cell activation as a costimulatory molecule. This study supports the novel mechanism of ubiquitination by GRAIL, identifies CD83 as a substrate of GRAIL, and ascribes a role for CD83 in CD4 T cell activation.
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Affiliation(s)
- Leon L. Su
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University, Stanford, CA 94040
| | - Hideyuki Iwai
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University, Stanford, CA 94040
| | - Jack T. Lin
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University, Stanford, CA 94040
| | - C. Garrison Fathman
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University, Stanford, CA 94040
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40
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Lin JT, Lineberry NB, Kattah MG, Su LL, Utz PJ, Fathman CG, Wu L. Naive CD4 t cell proliferation is controlled by mammalian target of rapamycin regulation of GRAIL expression. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2009; 182:5919-28. [PMID: 19414743 PMCID: PMC2853371 DOI: 10.4049/jimmunol.0803986] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In this study, we demonstrate that the E3 ubiquitin ligase gene related to anergy in lymphocytes (GRAIL) is expressed in quiescent naive mouse and human CD4 T cells and has a functional role in inhibiting naive T cell proliferation. Following TCR engagement, CD28 costimulation results in the expression of IL-2 whose signaling through its receptor activates the Akt-mammalian target of rapamycin (mTOR) pathway. Activation of mTOR allows selective mRNA translation, including the epistatic regulator of GRAIL, Otubain-1 (Otub1), whose expression results in the degradation of GRAIL and allows T cell proliferation. The activation of mTOR appears to be the critical component of IL-2R signaling regulating GRAIL expression. CTLA4-Ig treatment blocks CD28 costimulation and resultant IL-2 expression, whereas rapamycin and anti-IL-2 treatment block mTOR activation downstream of IL-2R signaling. Thus, all three of these biotherapeutics inhibit mTOR-dependent translation of mRNA transcripts, resulting in blockade of Otub1 expression, maintenance of GRAIL, and inhibition of CD4 T cell proliferation. These observations provide a mechanistic pathway sequentially linking CD28 costimulation, IL-2R signaling, and mTOR activation as important requirements for naive CD4 T cell proliferation through the regulation of Otub1 and GRAIL expression. Our findings also extend the role of GRAIL beyond anergy induction and maintenance, suggesting that endogenous GRAIL regulates general cell cycle and proliferation of primary naive CD4 T cells.
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Affiliation(s)
- Jack T. Lin
- Stanford University School of Medicine, Department of Medicine, Division of Immunology and Rheumatology, Stanford, CA 94305
| | - Neil B. Lineberry
- Stanford University School of Medicine, Department of Medicine, Division of Immunology and Rheumatology, Stanford, CA 94305
| | - Michael G. Kattah
- Stanford University School of Medicine, Department of Medicine, Division of Immunology and Rheumatology, Stanford, CA 94305
| | - Leon L. Su
- Stanford University School of Medicine, Department of Medicine, Division of Immunology and Rheumatology, Stanford, CA 94305
| | - Paul J. Utz
- Stanford University School of Medicine, Department of Medicine, Division of Immunology and Rheumatology, Stanford, CA 94305
| | - C. Garrison Fathman
- Stanford University School of Medicine, Department of Medicine, Division of Immunology and Rheumatology, Stanford, CA 94305
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41
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Abstract
Protein ubiquitylation has emerged as a key mechanism that regulates immune responses. Much like phosphorylation, ubiquitylation is a reversible covalent modification that regulates the stability, activity and localization of target proteins. As such, ubiquitylation regulates the development of the immune system and many phases of the immune response, including its initiation, propagation and termination. Recent work has shown that several ubiquitin ligases help to prevent the immune system from attacking self tissues. The dysfunction of several ubiquitin ligases has been linked to autoimmune diseases.
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Affiliation(s)
- Vijay G Bhoj
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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42
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Bocock JP, Carmicle S, Chhotani S, Ruffolo MR, Chu H, Erickson AH. The PA-TM-RING protein RING finger protein 13 is an endosomal integral membrane E3 ubiquitin ligase whose RING finger domain is released to the cytoplasm by proteolysis. FEBS J 2009; 276:1860-77. [PMID: 19292867 DOI: 10.1111/j.1742-4658.2009.06913.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PA-TM-RING proteins have an N-terminal protease-associated domain, a structure found in numerous proteases and implicated in protein binding, and C-terminal RING finger and PEST domains. Homologous proteins include GRAIL (gene related to anergy in leukocytes), which controls T-cell anergy, and AtRMR1 (receptor homology region-transmembrane domain-RING-H2 motif protein), a plant protein storage vacuole sorting receptor. Another family member, chicken RING zinc finger (C-RZF), was identified as being upregulated in embryonic chicken brain cells grown in the presence of tenascin-C. Despite algorithm predictions that the cDNA encodes a signal peptide and transmembrane domain, the protein was found in the nucleus. We showed that RING finger protein 13 (RNF13), the murine homolog of C-RZF, is a type I integral membrane protein localized in the endosomal/lysosomal system. By quantitative real-time RT-PCR analysis, we demonstrated that expression of RNF13 is increased in adult relative to embryonic mouse tissues and is upregulated in B35 neuroblastoma cells stimulated to undergo neurite outgrowth. We found that RNF13 is very labile, being subject to extensive proteolysis that releases both the protein-associated domain and the RING domain from the membrane. By analyzing microsomes, we showed that the ectodomain is shed into the lumen of vesicles, whereas the C-terminal half, which possesses the RING finger, is released to the cytoplasm. This C-terminal fragment of RNF13 has the ability to mediate ubiquitination. Proteolytic release of RNF13 from a membrane anchor thus provides unique spatial and temporal regulation that has not been previously described for an endosomal E3 ubiquitin ligase.
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Affiliation(s)
- Jeffrey P Bocock
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA
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43
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Taylor JJ, Krawczyk CM, Mohrs M, Pearce EJ. Th2 cell hyporesponsiveness during chronic murine schistosomiasis is cell intrinsic and linked to GRAIL expression. J Clin Invest 2009; 119:1019-28. [PMID: 19258704 DOI: 10.1172/jci36534] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Accepted: 01/07/2009] [Indexed: 12/13/2022] Open
Abstract
Chronic infections are associated with progressively declining T cell function. Infections with helminth parasites, such as Schistosoma mansoni, are often chronic and characterized by the development of strong Th2 responses that peak during the acute stage of infection and then decline despite ongoing infection; this minimizes Th2-dependent immunopathology during the chronic stage of infection. We sought to understand the basis for the decline in Th2 responses in chronic schistosomiasis. Using IL-4 reporter mice (mice that express EGFP as a reporter for Il4 gene expression) to identify Th2 cells, we found that Th2 cell numbers plateaued during acute infection and remained constant thereafter. However, the percentages of Th2 cells proliferating during late infection were strikingly lower than those during acute infection. Th2 cell hyporesponsiveness was evident within 10 d of initiation of the Th2 response and became progressively ingrained thereafter, in response to repeated Ag stimulation. Gene expression analyses implicated the E3-ubiquitin ligase gene related to anergy in lymphocytes (GRAIL) in the hyporesponsive state. Consistent with this, suppression of GRAIL expression using retrovirally delivered siRNA prevented the development of hyporesponsiveness induced by repeated Ag stimulation in vitro or in vivo. Together, these data indicate that the decline in Th2 cell responsiveness during chronic schistosomiasis is the net result of the upregulation of GRAIL expression in response to repeated Ag stimulation.
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Affiliation(s)
- Justin J Taylor
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-4539, USA
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44
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Abstract
Effective immune responses require the appropriate activation and differentiation of peripheral CD4(+) T cells. These processes need to be followed by the timely elimination of the responding T cells in order to restore T cell homeostasis. Defects in the appropriate regulation of T cell activation, expansion, and survival underlie the pathogenesis of many autoimmune disorders including SLE. The molecular machinery employed by T cells to properly control these processes and prevent the onset of autoimmunity has not been fully elucidated. Rho GTPases (which include the Rac, Cdc42, and Rho subfamilies) are molecular switches that control a wide range of cellular processes. Their fundamental role in biology is due to their ability to regulate both cytoskeletal dynamics and a large number of signal transduction pathways. Activation of Rho GTPases is now recognized as a key event in the coordination of immune responses and, particularly, in the activation of T cells. In this review, we will first provide an overview of the role of Rho GTPase-mediated pathways in mature CD4(+) T cells and then we will discuss recent studies, which suggest that deregulation of these pathways may play a role in the pathogenesis of SLE.
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Affiliation(s)
- Alessandra B Pernis
- Department of Medicine, Columbia University, 630 West 168th Street, New York, NY 10032, USA.
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45
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Targeted cleavage of signaling proteins by caspase 3 inhibits T cell receptor signaling in anergic T cells. Immunity 2008; 29:193-204. [PMID: 18701083 DOI: 10.1016/j.immuni.2008.06.010] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2007] [Revised: 03/26/2008] [Accepted: 06/10/2008] [Indexed: 11/22/2022]
Abstract
T cell receptor (TCR) engagement in the absence of costimulation induces the calcium-dependent upregulation of a program of gene expression that leads to the establishment of T cell anergy. Casp3 is one of the genes activated during anergy induction. Here we show that caspase 3 is required for the induction of T cell unresponsiveness. Suboptimal T cell stimulation induced caspase 3 activation, which did not result in cell death. Furthermore, caspase 3-deficient T cells showed impaired responses to anergizing stimuli. In anergic T cells, activated caspase 3 associated to the plasma membrane, where it cleaved and inactivated proteins such as the Grb2-related adaptor downstream of shc (GADS) and the guanine-nucleotide exchange factor Vav1, causing a blockade in TCR signaling. Our results identify a role for caspase 3 in nonapoptotic T cells and support that caspase 3-dependent proteolytic inactivation of signaling proteins is essential to maintain T cell tolerance.
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46
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Duré M, Macian F. IL-2 signaling prevents T cell anergy by inhibiting the expression of anergy-inducing genes. Mol Immunol 2008; 46:999-1006. [PMID: 18990450 DOI: 10.1016/j.molimm.2008.09.029] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Revised: 08/19/2008] [Accepted: 09/23/2008] [Indexed: 12/14/2022]
Abstract
T cell responses are determined by the environment in which antigen is encountered. In the absence of proper costimulation, anergizing stimuli induce the activation of a specific program of gene expression. Proteins encoded by these genes impose a state of functional unresponsiveness in anergic T cells through the activation of different mechanisms that include dampening of the T cell receptor signaling and direct inhibition of cytokine expression. Anergy can be reversed by stimulating T cells in the presence of interleukin (IL-)2. Signaling through the IL-2 receptor has been shown to activate mTOR, which plays an important role in the integration of signals that determine the fate of T cells. The mechanisms underlying the IL-2-dependent regulation of T cell tolerance are still not fully elucidated. In this study we show that IL-2 receptor signaling mediated through JAK3 and mTOR inhibits the expression of anergy-inducing genes independently of any effect on cell cycle progression. Interestingly, we also show that this effect is likely due to changes on the levels of AP-1 activation induced by IL-2 receptor signaling in T cells. Our data identifies a mechanism that can explain how IL-2 may prevent or reverse the establishment of anergy in T cells and, therefore, helps to understand how the cytokine environment can be determinant to shape the outcome of T cell responses - tolerance or activation - when antigen is encountered.
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Affiliation(s)
- Myrianne Duré
- Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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47
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Lineberry N, Su L, Soares L, Fathman CG. The single subunit transmembrane E3 ligase gene related to anergy in lymphocytes (GRAIL) captures and then ubiquitinates transmembrane proteins across the cell membrane. J Biol Chem 2008; 283:28497-505. [PMID: 18713730 DOI: 10.1074/jbc.m805092200] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ubiquitin E3 ligase gene related to anergy in lymphocytes (GRAIL) (Rnf128) is a type 1 transmembrane protein that induces T cell anergy through the ubiquitination activity of its cytosolic RING finger. GRAIL also contains an equally large luminal region consisting primarily of an uncharacterized protease-associated (PA) domain. Using two-hybrid technology to screen for proteins that bound the PA domain we identified CD151, a member of the tetraspanin family of membrane proteins. GRAIL bound to the luminal/extracellular portion of both CD151 and the related tetraspanin CD81 using its PA domain, which promoted ubiquitination of cytosolic lysine residues. GRAIL exhibited specificity for lysines only within the tetraspanin amino terminus even in the presence of other cytosolic lysine residues in the substrate. GRAIL-mediated ubiquitination promoted proteasomal degradation and cell surface down-regulation of tetraspanins via Lys-48 linkages. As a result, the juxtaposition of PA and RING finger domains across a lipid bilayer facilitates the capture of transmembrane substrates for subsequent ubiquitination. These findings identify for the first time a single subunit E3 ligase containing a substrate-binding domain spatially restricted by a membrane from its E2 recruitment domain as well as an E3 ligase for members of the tetraspanin family.
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Affiliation(s)
- Neil Lineberry
- Department of Medicine, Division of Immunology and Rheumatology, Stanford University School of Medicine, Stanford, California 94305, USA
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48
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Molecular regulation of T-cell anergy. EMBO Rep 2008; 9:50-5. [PMID: 18174897 DOI: 10.1038/sj.embor.7401138] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Accepted: 11/13/2007] [Indexed: 11/09/2022] Open
Abstract
The activation of T cells is tightly controlled by many positive and negative regulatory processes. This fine-tuning allows productive immunity to pathogens while minimizing the risk of autoimmunity. One negative regulatory mechanism is clonal anergy, which is a hyporesponsive state that occurs when T cells are activated through the T-cell antigen receptor in the absence of appropriate co-stimulatory signals. Recent studies have confirmed a crucial role for defective Ras activation in mediating this hyporesponsive state. Diminished Ras activation can, in part, be explained by the upregulated expression of diacylglycerol kinases (DGKs), which phosphorylate diacylglycerol and restrict Ras guanyl releasing protein 1 (RasGRP1)-dependent activation of Ras. Increased expression of DGKs is probably transcriptional and is accompanied by augmented expression of additional negative regulators, including the transcription factors early growth response (Egr) 2 and Egr3, and the E3 ubiquitin ligases known as gene related to anergy in lymphocytes (GRAIL) and Casitas B-cell lymphoma-b (Cbl-b). A model is emerging for how these factors are regulated to control T-cell responsiveness.
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49
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Gómez-Martín D, Díaz-Zamudio M, Alcocer-Varela J. Ubiquitination system and autoimmunity: The bridge towards the modulation of the immune response. Autoimmun Rev 2008; 7:284-90. [DOI: 10.1016/j.autrev.2007.11.026] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Accepted: 11/01/2007] [Indexed: 11/25/2022]
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Lin AE, Mak TW. The role of E3 ligases in autoimmunity and the regulation of autoreactive T cells. Curr Opin Immunol 2007; 19:665-73. [PMID: 18036806 DOI: 10.1016/j.coi.2007.10.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Revised: 10/01/2007] [Accepted: 10/02/2007] [Indexed: 11/30/2022]
Abstract
The ubiquitination of proteins by E3 ligases has become an important regulatory mechanism for a variety of immune functions, including the maintenance of self tolerance and suppression of autoreactive T cell development. This review highlights recent advances in our knowledge of the functions in this context of known and potential E3 ligases, including autoimmune regulator (AIRE), TNF receptor-associated factor 6 (TRAF6), Casitas B cell lymphoma b (Cbl-b), gene related to anergy in lymphocytes (GRAIL), Itch, and Roquin. We discuss how disruptions to these molecules may contribute to the loss of T cell homeostasis and the pathogenesis of autoimmunity. We also report on the implications of the potential coordinated actions of these molecules for T cell anergy and regulatory T cell (Treg) functions. The great diversity of E3 ligases and the growing list of cellular processes in which ubiquitination plays a role make for an exciting field of research. Findings emerging from these investigations may suggest ways to exploit the therapeutic potential of manipulating ubiquitination, particularly for autoimmune disorders.
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Affiliation(s)
- Amy Erica Lin
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
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