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McFarlane A, Pohler E, Moraga I. Molecular and cellular factors determining the functional pleiotropy of cytokines. FEBS J 2023; 290:2525-2552. [PMID: 35246947 PMCID: PMC10952290 DOI: 10.1111/febs.16420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 01/26/2022] [Accepted: 03/03/2022] [Indexed: 11/30/2022]
Abstract
Cytokines are soluble factors vital for mammalian physiology. Cytokines elicit highly pleiotropic activities, characterized by their ability to induce a wide spectrum of functional responses in a diverse range of cell subsets, which makes their study very challenging. Cytokines activate signalling via receptor dimerization/oligomerization, triggering activation of the JAK (Janus kinase)/STAT (signal transducer and activator of transcription) signalling pathway. Given the strong crosstalk and shared usage of key components of cytokine signalling pathways, a long-standing question in the field pertains to how functional diversity is achieved by cytokines. Here, we discuss how biophysical - for example, ligand-receptor binding affinity and topology - and cellular - for example, receptor, JAK and STAT protein levels, endosomal compartment - parameters contribute to the modulation and diversification of cytokine responses. We review how these parameters ultimately converge into a common mechanism to fine-tune cytokine signalling that involves the control of the number of Tyr residues phosphorylated in the receptor intracellular domain upon cytokine stimulation. This results in different kinetics of STAT activation, and induction of specific gene expression programs, ensuring the generation of functional diversity by cytokines using a limited set of signalling intermediaries. We describe how these first principles of cytokine signalling have been exploited using protein engineering to design cytokine variants with more specific and less toxic responses for immunotherapy.
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Affiliation(s)
- Alison McFarlane
- Division of Cell Signalling and ImmunologySchool of Life SciencesUniversity of DundeeUK
| | - Elizabeth Pohler
- Division of Cell Signalling and ImmunologySchool of Life SciencesUniversity of DundeeUK
| | - Ignacio Moraga
- Division of Cell Signalling and ImmunologySchool of Life SciencesUniversity of DundeeUK
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2
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Somin S, Kulasiri D, Samarasinghe S. Alleviating the unwanted effects of oxidative stress on Aβ clearance: a review of related concepts and strategies for the development of computational modelling. Transl Neurodegener 2023; 12:11. [PMID: 36907887 PMCID: PMC10009979 DOI: 10.1186/s40035-023-00344-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 02/21/2023] [Indexed: 03/14/2023] Open
Abstract
Treatment for Alzheimer's disease (AD) can be more effective in the early stages. Although we do not completely understand the aetiology of the early stages of AD, potential pathological factors (amyloid beta [Aβ] and tau) and other co-factors have been identified as causes of AD, which may indicate some of the mechanism at work in the early stages of AD. Today, one of the primary techniques used to help delay or prevent AD in the early stages involves alleviating the unwanted effects of oxidative stress on Aβ clearance. 4-Hydroxynonenal (HNE), a product of lipid peroxidation caused by oxidative stress, plays a key role in the adduction of the degrading proteases. This HNE employs a mechanism which decreases catalytic activity. This process ultimately impairs Aβ clearance. The degradation of HNE-modified proteins helps to alleviate the unwanted effects of oxidative stress. Having a clear understanding of the mechanisms associated with the degradation of the HNE-modified proteins is essential for the development of strategies and for alleviating the unwanted effects of oxidative stress. The strategies which could be employed to decrease the effects of oxidative stress include enhancing antioxidant activity, as well as the use of nanozymes and/or specific inhibitors. One area which shows promise in reducing oxidative stress is protein design. However, more research is needed to improve the effectiveness and accuracy of this technique. This paper discusses the interplay of potential pathological factors and AD. In particular, it focuses on the effect of oxidative stress on the expression of the Aβ-degrading proteases through adduction of the degrading proteases caused by HNE. The paper also elucidates other strategies that can be used to alleviate the unwanted effects of oxidative stress on Aβ clearance. To improve the effectiveness and accuracy of protein design, we explain the application of quantum mechanical/molecular mechanical approach.
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Affiliation(s)
- Sarawoot Somin
- Centre for Advanced Computational Solutions (C-fACS), Lincoln University, Christchurch, 7647, New Zealand.,Department of Wine, Food and Molecular Biosciences, Lincoln University, Christchurch, 7647, New Zealand
| | - Don Kulasiri
- Centre for Advanced Computational Solutions (C-fACS), Lincoln University, Christchurch, 7647, New Zealand. .,Department of Wine, Food and Molecular Biosciences, Lincoln University, Christchurch, 7647, New Zealand.
| | - Sandhya Samarasinghe
- Centre for Advanced Computational Solutions (C-fACS), Lincoln University, Christchurch, 7647, New Zealand
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3
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Charpentier JC, King PD. Mechanisms and functions of endocytosis in T cells. Cell Commun Signal 2021; 19:92. [PMID: 34503523 PMCID: PMC8427877 DOI: 10.1186/s12964-021-00766-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 07/17/2021] [Indexed: 11/11/2022] Open
Abstract
Once thought of primarily as a means to neutralize pathogens or to facilitate feeding, endocytosis is now known to regulate a wide range of eukaryotic cell processes. Among these are regulation of signal transduction, mitosis, lipid homeostasis, and directed migration, among others. Less well-appreciated are the roles various forms of endocytosis plays in regulating αβ and, especially, γδ T cell functions, such as T cell receptor signaling, antigen discovery by trogocytosis, and activated cell growth. Herein we examine the contribution of both clathrin-mediated and clathrin-independent mechanisms of endocytosis to T cell biology. Video Abstract
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Affiliation(s)
- John C Charpentier
- Department of Microbiology and Immunology, University of Michigan Medical School, 6606 Med Sci II, 1150 West Medical Center Drive, Ann Arbor, MI, 48109-5620, USA
| | - Philip D King
- Department of Microbiology and Immunology, University of Michigan Medical School, 6606 Med Sci II, 1150 West Medical Center Drive, Ann Arbor, MI, 48109-5620, USA.
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4
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Wang M, Wu H, Li S, Xu Z, Li X, Yang Y, Li B, Li Y, Guo J, Chen H. SYNJ2BP promotes the degradation of PTEN through the lysosome-pathway and enhances breast tumor metastasis via PI3K/AKT/SNAI1 signaling. Oncotarget 2017; 8:89692-89706. [PMID: 29163781 PMCID: PMC5685702 DOI: 10.18632/oncotarget.21058] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 09/03/2017] [Indexed: 12/22/2022] Open
Abstract
SYNJ2BP plays an important role in breast cancer metastasis. However, the molecular mechanism associated with the function of SYNJ2BP in metastasis remains unclear. In this study, we investigated the role of SYNJ2BP in tumor metastasis and established the associated underlying mechanism. Over-expression of SYNJ2BP promoted both cell migration and invasion. In contrast, silencing SYNJ2BP caused the suppression of cell migration and invasion. SYNJ2BP increased the levels of phosphorylation for AKT and GSK3β, which could be inhibited by the PI3K inhibitor, LY294002, and the GSK3β inhibitor, LiCl, and regulated the accumulation of SNAI1 in the nucleus and the expression of the SNAI1 target gene, E-cadherin (EMT marker). It is known that the stability of PTEN is regulated by ubiquitination. However, in this study, we additionally demonstrated that SYNJ2BP mediated the degradation of PTEN protein by the lysosome-pathway and induced the activation of PI3K/AKT signaling by promoting the co-localization of PTEN with autophagy-lysosomes and the expression of LC3-II and p62. In vivo study, the overexpression of SYNJ2BP significantly increased the metastasis of 4T1 cells in BALB/c mice. In addition, SYNJ2BP was highly expressed in breast carcinoma (p = 0.0031), but not in normal breast tissue, while analysis of tissue samples taken from SNAI1-positive human breast cancers showed a significant correlation between the expression of SYNJ2BP and that of p-AKT (p < 0.005). Collectively, our data identified a tumor inducer, SYNJ2BP, which could activate the PI3K/AKT/GSK3β/SNAI1 signaling pathway through the lysosome-mediated degradation of PTEN, and promote both EMT and tumor metastasis during the progression of breast cancer.
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Affiliation(s)
- Miao Wang
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China
| | - Huijian Wu
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China.,School of Life Science and Medicine, Dalian University of Technology, Panjin, China
| | - Shujing Li
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China
| | - Zhaowei Xu
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China
| | - Xiahui Li
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China
| | - Yangyang Yang
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China
| | - Bowen Li
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China
| | - Yanan Li
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China
| | - Jing Guo
- School of Life Science and Medicine, Dalian University of Technology, Panjin, China
| | - Huan Chen
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China
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Wang S, Liu H, Zu X, Liu Y, Chen L, Zhu X, Zhang L, Zhou Z, Xiao G, Wang W. The ubiquitin-proteasome system is essential for the productive entry of Japanese encephalitis virus. Virology 2016; 498:116-127. [DOI: 10.1016/j.virol.2016.08.013] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 07/27/2016] [Accepted: 08/17/2016] [Indexed: 11/26/2022]
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6
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Influence of cellular trafficking pathway on bluetongue virus infection in ovine cells. Viruses 2015; 7:2378-403. [PMID: 25984713 PMCID: PMC4452911 DOI: 10.3390/v7052378] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 05/06/2015] [Indexed: 11/27/2022] Open
Abstract
Bluetongue virus (BTV), a non-enveloped arbovirus, causes hemorrhagic disease in ruminants. However, the influence of natural host cell proteins on BTV replication process is not defined. In addition to cell lysis, BTV also exits non-ovine cultured cells by non-lytic pathways mediated by nonstructural protein NS3 that interacts with virus capsid and cellular proteins belonging to calpactin and ESCRT family. The PPXY late domain motif known to recruit NEDD4 family of HECT ubiquitin E3 ligases is also highly conserved in NS3. In this study using a mixture of molecular, biochemical and microscopic techniques we have analyzed the importance of ovine cellular proteins and vesicles in BTV infection. Electron microscopic analysis of BTV infected ovine cells demonstrated close association of mature particles with intracellular vesicles. Inhibition of Multi Vesicular Body (MVB) resident lipid phosphatidylinositol-3-phosphate resulted in decreased total virus titre suggesting that the vesicles might be MVBs. Proteasome mediated inhibition of ubiquitin or modification of virus lacking the PPXY in NS3 reduced virus growth. Thus, our study demonstrated that cellular components comprising of MVB and exocytic pathways proteins are involved in BTV replication in ovine cells.
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Abstract
There are many pathways of endocytosis at the cell surface that apparently operate at the same time. With the advent of new molecular genetic and imaging tools, an understanding of the different ways by which a cell may endocytose cargo is increasing by leaps and bounds. In this review we explore pathways of endocytosis that occur in the absence of clathrin. These are referred to as clathrin-independent endocytosis (CIE). Here we primarily focus on those pathways that function at the small scale in which some have distinct coats (caveolae) and others function in the absence of specific coated intermediates. We follow the trafficking itineraries of the material endocytosed by these pathways and finally discuss the functional roles that these pathways play in cell and tissue physiology. It is likely that these pathways will play key roles in the regulation of plasma membrane area and tension and also control the availability of membrane during cell migration.
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Affiliation(s)
- Satyajit Mayor
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, and Institute for Stem Cell Biology and Regenerative Medicine, Bangalore 560065, India
| | - Robert G Parton
- The University of Queensland, Institute for Molecular Bioscience and Centre for Microscopy and Microanalysis, Queensland 4072, Brisbane, Australia
| | - Julie G Donaldson
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892
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Kim SH, Kim MO, Cho YY, Yao K, Kim DJ, Jeong CH, Yu DH, Bae KB, Cho EJ, Jung SK, Lee MH, Chen H, Kim JY, Bode AM, Dong Z. ERK1 phosphorylates Nanog to regulate protein stability and stem cell self-renewal. Stem Cell Res 2014; 13:1-11. [PMID: 24793005 DOI: 10.1016/j.scr.2014.04.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 03/27/2014] [Accepted: 04/01/2014] [Indexed: 10/25/2022] Open
Abstract
Nanog regulates human and mouse embryonic stem (ES) cell self-renewal activity. Activation of ERKs signaling negatively regulates ES cell self-renewal and induces differentiation, but the mechanisms are not understood. We found that ERK1 binds and phosphorylates Nanog. Activation of MEK/ERKs signaling and phosphorylation of Nanog inhibit Nanog transactivation, inducing ES cell differentiation. Conversely, suppression of MEK/ERKs signaling enhances Nanog transactivation to inhibit ES cell differentiation. We observed that phosphorylation of Nanog by ERK1 decreases Nanog stability through ubiquitination-mediated protein degradation. Further, we found that this phosphorylation induces binding of FBXW8 with Nanog to reduce Nanog protein stability. Overall, our results demonstrated that ERKs-mediated Nanog phosphorylation plays an important role in self-renewal of ES cells through FBXW8-mediated Nanog protein stability.
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Affiliation(s)
- Sung-Hyun Kim
- The Hormel Institute, University of Minnesota, 801, 16th AVE, NE, Austin, MN 55912, USA; Kyungpook National University, Center for Laboratory Animal Resources, School of Animal BT Science, Department of Biochemistry, School of Dentistry, Dae-gu, Republic of Korea
| | - Myoung Ok Kim
- The Hormel Institute, University of Minnesota, 801, 16th AVE, NE, Austin, MN 55912, USA; Kyungpook National University, Center for Laboratory Animal Resources, School of Animal BT Science, Department of Biochemistry, School of Dentistry, Dae-gu, Republic of Korea
| | - Yong-Yeon Cho
- The Hormel Institute, University of Minnesota, 801, 16th AVE, NE, Austin, MN 55912, USA
| | - Ke Yao
- The Hormel Institute, University of Minnesota, 801, 16th AVE, NE, Austin, MN 55912, USA
| | - Dong Joon Kim
- The Hormel Institute, University of Minnesota, 801, 16th AVE, NE, Austin, MN 55912, USA
| | - Chul-Ho Jeong
- The Hormel Institute, University of Minnesota, 801, 16th AVE, NE, Austin, MN 55912, USA
| | - Dong Hoon Yu
- The Hormel Institute, University of Minnesota, 801, 16th AVE, NE, Austin, MN 55912, USA
| | - Ki Beom Bae
- The Hormel Institute, University of Minnesota, 801, 16th AVE, NE, Austin, MN 55912, USA
| | - Eun Jin Cho
- The Hormel Institute, University of Minnesota, 801, 16th AVE, NE, Austin, MN 55912, USA
| | - Sung Keun Jung
- The Hormel Institute, University of Minnesota, 801, 16th AVE, NE, Austin, MN 55912, USA
| | - Mee Hyun Lee
- The Hormel Institute, University of Minnesota, 801, 16th AVE, NE, Austin, MN 55912, USA
| | - Hanyong Chen
- The Hormel Institute, University of Minnesota, 801, 16th AVE, NE, Austin, MN 55912, USA
| | - Jae Young Kim
- Kyungpook National University, Center for Laboratory Animal Resources, School of Animal BT Science, Department of Biochemistry, School of Dentistry, Dae-gu, Republic of Korea
| | - Ann M Bode
- The Hormel Institute, University of Minnesota, 801, 16th AVE, NE, Austin, MN 55912, USA
| | - Zigang Dong
- The Hormel Institute, University of Minnesota, 801, 16th AVE, NE, Austin, MN 55912, USA.
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9
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Wei Q, Sha Y, Bhattacharya A, Abdel Fattah E, Bonilla D, Jyothula SSSK, Pandit L, Khurana Hershey GK, Eissa NT. Regulation of IL-4 receptor signaling by STUB1 in lung inflammation. Am J Respir Crit Care Med 2014; 189:16-29. [PMID: 24251647 DOI: 10.1164/rccm.201305-0874oc] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
RATIONALE IL-4Rα, the common receptor component for IL-4 and IL-13, plays a critical role in IL-4- and IL-13-mediated signaling pathways that regulate airway inflammation and remodeling. However, the regulatory mechanisms underlying IL-4Rα turnover and its signal termination remain elusive. OBJECTIVES To evaluate the role of STUB1 (STIP1 homology and U-Box containing protein 1) in regulating IL-4R signaling in airway inflammation. METHODS The roles of STUB1 in IL-4Rα degradation and its signaling were investigated by immunoblot, immunoprecipitation, and flow cytometry. The involvement of STUB1 in airway inflammation was determined in vivo by measuring lung inflammatory cells infiltration, mucus production, serum lgE levels, and alveolar macrophage M2 activation in STUB1(-/-) mice. STUB1 expression was evaluated in airway epithelium of patients with asthma and lung tissues of subjects with chronic obstructive pulmonary disease. MEASUREMENTS AND MAIN RESULTS STUB1 interacted with IL-4Rα and targeted it for ubiquitination-mediated proteasomal degradation, terminating IL-4 or IL-13 signaling. STUB1 knockout cells showed increased levels of IL-4Rα and sustained STAT6 activation, whereas STUB1 overexpression reduced IL-4Rα levels. Mice deficient in STUB1 had spontaneous airway inflammation, alternative M2 activation of alveolar macrophage, and increased serum IgE. STUB1 levels were increased in airways of subjects with asthma or chronic obstructive pulmonary disease, suggesting that up-regulation of STUB1 might be an important feedback mechanism to dampen IL-4R signaling in airway inflammation. CONCLUSIONS Our study identified a previously uncharacterized role for STUB1 in regulating IL-4R signaling, which might provide a new strategy for attenuating airway inflammation.
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Affiliation(s)
- Qin Wei
- 1 Department of Medicine, Baylor College of Medicine, Houston, Texas; and
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10
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Moraga I, Spangler J, Mendoza JL, Garcia KC. Multifarious determinants of cytokine receptor signaling specificity. Adv Immunol 2014; 121:1-39. [PMID: 24388212 DOI: 10.1016/b978-0-12-800100-4.00001-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cytokines play crucial roles in regulating immune homeostasis. Two important characteristics of most cytokines are pleiotropy, defined as the ability of one cytokine to exhibit diverse functionalities, and redundancy, defined as the ability of multiple cytokines to exert overlapping activities. Identifying the determinants for unique cellular responses to cytokines in the face of shared receptor usage, pleiotropy, and redundancy will be essential in order to harness the potential of cytokines as therapeutics. Here, we discuss the biophysical (ligand-receptor geometry and affinity) and cellular (receptor trafficking and intracellular abundance of signaling molecules) parameters that contribute to the specificity of cytokine bioactivities. Whereas the role of extracellular ternary complex geometry in cytokine-induced signaling is still not completely elucidated, cytokine-receptor affinity is known to impact signaling through modulation of the stability and kinetics of ternary complex formation. Receptor trafficking also plays an important and likely underappreciated role in the diversification of cytokine bioactivities but it has been challenging to experimentally probe trafficking effects. We also review recent efforts to quantify levels of intracellular signaling components, as second messenger abundance can affect cytokine-induced bioactivities both quantitatively and qualitatively. We conclude by discussing the application of protein engineering to develop therapeutically relevant cytokines with reduced pleiotropy and redirected biological functionalities.
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Affiliation(s)
- Ignacio Moraga
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, USA; Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, California, USA; Program in Immunology, Stanford University School of Medicine, Stanford, California, USA
| | - Jamie Spangler
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, USA; Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, California, USA; Program in Immunology, Stanford University School of Medicine, Stanford, California, USA
| | - Juan L Mendoza
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, USA; Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, California, USA; Program in Immunology, Stanford University School of Medicine, Stanford, California, USA
| | - K Christopher Garcia
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, USA; Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, California, USA; Program in Immunology, Stanford University School of Medicine, Stanford, California, USA.
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11
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Pan W, Stone KP, Hsuchou H, Manda VK, Zhang Y, Kastin AJ. Cytokine signaling modulates blood-brain barrier function. Curr Pharm Des 2013; 17:3729-40. [PMID: 21834767 DOI: 10.2174/138161211798220918] [Citation(s) in RCA: 158] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 08/30/2011] [Accepted: 09/26/2011] [Indexed: 02/06/2023]
Abstract
The blood-brain barrier (BBB) provides a vast interface for cytokines to affect CNS function. The BBB is a target for therapeutic intervention. It is essential, therefore, to understand how cytokines interact with each other at the level of the BBB and how secondary signals modulate CNS functions beyond the BBB. The interactions between cytokines and lipids, however, have not been fully addressed at the level of the BBB. Here, we summarize current understanding of the localization of cytokine receptors and transporters in specific membrane microdomains, particularly lipid rafts, on the luminal (apical) surface of the microvascular endothelial cells composing the BBB. We then illustrate the clinical context of cytokine effects on the BBB by neuroendocrine regulation and amplification of inflammatory signals. Two unusual aspects discussed are signaling crosstalk by different classes of cytokines and genetic regulation of drug efflux transporters. We also introduce a novel area of focus on how cytokines may act through nuclear hormone receptors to modulate efflux transporters and other targets. A specific example discussed is the ATP-binding cassette transporter-1 (ABCA-1) that regulates lipid metabolism. Overall, cytokine signaling at the level of the BBB is a crucial feature of the dynamic regulation that can rapidly change BBB function and affect brain health and disease.
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Affiliation(s)
- Weihong Pan
- Blood-Brain Barrier Group, Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA 70808, USA
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12
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Hoover RG, Gullickson G, Kornbluth J. Natural killer lytic-associated molecule plays a role in controlling tumor dissemination and metastasis. Front Immunol 2012; 3:393. [PMID: 23269922 PMCID: PMC3529306 DOI: 10.3389/fimmu.2012.00393] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 12/06/2012] [Indexed: 01/23/2023] Open
Abstract
Natural killer lytic-associated molecule (NKLAM) is an E3 ubiquitin ligase that plays a major role in the cytolytic activity of NK cells. NKLAM is rapidly synthesized and then targeted to the granule membranes of NK cells upon NK activation. Previous studies have shown an essential role for NKLAM in NK killing activity in vitro. These findings were extended to an in vivo model of NK-mediated tumor killing in which NKLAM-deficient knockout (KO) mice injected with B16 melanoma cells were found to have significantly higher numbers of pulmonary tumor nodules than wild-type (WT) mice. To further investigate the role of NKLAM and NK function in tumor immunity in vivo, we utilized additional tumor models to compare tumor development and progression in NKLAM KO and WT mice. Primary tumor growth, dissemination, and metastasis of RMA-S lymphoma cells and E0771 breast cancer cells were evaluated. Both tumor cell lines were stably transfected with constructs that allow expression of green fluorescent protein (GFP), which serves as a tumor-specific marker. Intravenous injection of NK-sensitive RMA-S lymphoma cells resulted in greater dissemination of lymphoma cells in NKLAM KO mice than in WT mice. Lymphoma cells were found in the lymph nodes and bone marrow (BM) of NKLAM KO mice 2 weeks after injection; few detectable tumor cells remained in WT mice. E0771 syngeneic breast cancer cells were injected into the mammary pads of NKLAM KO and WT mice. Primary tumor growth was greater in NKLAM KO than in WT mice. More significantly, there were 4–5-fold more tumor cells in the blood and lungs of NKLAM KO than in WT mice 2 weeks after injection of tumor cells into the mammary pad. These results indicate that NKLAM plays a role in tumor development in vivo, especially in controlling tumor dissemination and metastasis to distant sites.
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Affiliation(s)
- Richard G Hoover
- Department of Pathology, Saint Louis University School of Medicine St. Louis, MO, USA
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13
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Ritchie M, Tchistiakova L, Scott N. Implications of receptor-mediated endocytosis and intracellular trafficking dynamics in the development of antibody drug conjugates. MAbs 2012; 5:13-21. [PMID: 23221464 PMCID: PMC3564878 DOI: 10.4161/mabs.22854] [Citation(s) in RCA: 185] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The use of antibody-drug conjugates (ADCs) as a therapeutic platform to treat cancer has recently gained substantial momentum. This therapeutic modality has the potential to increase the efficacy and reduce the systemic toxicity associated with current therapeutic regimens. The efficacy of ADCs, however, relies on the proper exploitation of intracellular sorting dynamics of the antigen as well as the specificity, selectivity and pharmacokinetic properties of the antibody itself. Our understanding of endocytosis and endosomal trafficking of receptors has appreciably increased in recent years, as improvements in the assays used to study these events have resolved many of the molecular mechanisms regulating these processes. As a result, we now have the knowledge necessary to exploit these pathways efficiently to improve the efficacy of antibody-based therapy. This review discusses some recent studies that have explored how endo/lysosomal dynamics can affect the efficacy of engineered therapeutic antibodies, including ADCs.
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Affiliation(s)
- Michael Ritchie
- Global Biotherapeutic Technologies, Pfizer Global Research and Development, Cambridge, MA, USA
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14
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Mandel I, Paperna T, Volkowich A, Merhav M, Glass-Marmor L, Miller A. The ubiquitin-proteasome pathway regulates claudin 5 degradation. J Cell Biochem 2012; 113:2415-23. [PMID: 22389112 DOI: 10.1002/jcb.24118] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The tight junctions (TJs) form continuous intracellular contacts, which help create selective barriers in epithelial and endothelial cell layers. The structures created by the TJs are very dynamic and can be rapidly remodeled in response to physiological and pathological signals. Claudin 5 is a membranal TJ protein which plays a critical role in determining the permeability of endothelial barriers. We describe the regulation of claudin 5 degradation by the ubiquitin-proteasome system (UPS). Our results indicate that claudin 5 has a relatively short half-life and can be polyubiquitinated on lysine 199. This ubiquitination appears to trigger the proteasome-dependent degradation of claudin 5. Other mechanisms also seem to be involved in the post-translational regulation of claudin 5, including a ubiquitin-independent and probably indirect lysosomal-dependent pathway. These findings provide evidence for the involvement of the UPS in the regulation of claudin 5 levels, and set the stage for further research to determine the involvement of this pathway in the modulation of the properties of TJs and cell-layer barriers.
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Affiliation(s)
- Ilana Mandel
- Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
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15
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Zhao J, Wei J, Mialki RK, Mallampalli DF, Chen BB, Coon T, Zou C, Mallampalli RK, Zhao Y. F-box protein FBXL19-mediated ubiquitination and degradation of the receptor for IL-33 limits pulmonary inflammation. Nat Immunol 2012; 13:651-8. [PMID: 22660580 DOI: 10.1038/ni.2341] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 05/09/2012] [Indexed: 12/15/2022]
Abstract
The ST2L receptor for interleukin 33 (IL-33) mediates pulmonary inflammation and immune system-related disorders, such as asthma and rheumatoid arthritis. At present, very little is known about the molecular regulation of ST2L expression. Here we found that FBXL19, an 'orphan' member of the Skp1-Cullin-F-box family of E3 ubiquitin ligases, selectively bound to ST2L to mediate its polyubiquitination and elimination in the proteasome. Degradation of ST2L involved phosphorylation of ST2L at Ser442 catalyzed by the kinase GSK3β. Overexpression of FBXL19 abrogated the proapoptotic and inflammatory effects of IL-33 and lessened the severity of lung injury in mouse models of pneumonia. Our results suggest that modulation of the IL-33-ST2L axis by ubiquitin ligases might serve as a unique strategy for lessening pulmonary inflammation.
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Affiliation(s)
- Jing Zhao
- Department of Medicine and the Acute Lung Injury Center of Excellence, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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16
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Greene W, Zhang W, He M, Witt C, Ye F, Gao SJ. The ubiquitin/proteasome system mediates entry and endosomal trafficking of Kaposi's sarcoma-associated herpesvirus in endothelial cells. PLoS Pathog 2012; 8:e1002703. [PMID: 22615563 PMCID: PMC3355089 DOI: 10.1371/journal.ppat.1002703] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 03/30/2012] [Indexed: 01/12/2023] Open
Abstract
Ubiquitination, a post-translational modification, mediates diverse cellular functions including endocytic transport of molecules. Kaposi's sarcoma-associated herpesvirus (KSHV), an enveloped herpesvirus, enters endothelial cells primarily through clathrin-mediated endocytosis. Whether ubiquitination and proteasome activity regulates KSHV entry and endocytosis remains unknown. We showed that inhibition of proteasome activity reduced KSHV entry into endothelial cells and intracellular trafficking to nuclei, thus preventing KSHV infection of the cells. Three-dimensional (3-D) analyses revealed accumulation of KSHV particles in a cytoplasmic compartment identified as EEA1+ endosomal vesicles upon proteasome inhibition. KSHV particles are colocalized with ubiquitin-binding proteins epsin and eps15. Furthermore, ubiquitination mediates internalization of both KSHV and one of its receptors integrin β1. KSHV particles are colocalized with activated forms of the E3 ligase c-Cbl. Knock-down of c-Cbl or inhibition of its phosphorylation reduced viral entry and intracellular trafficking, resulting in decreased KSHV infectivity. These results demonstrate that ubiquitination mediates internalization of both KSHV and one of its cognate receptors integrin β1, and identify c-Cbl as a potential E3 ligase that facilitates this process. Ubiquitination, a post-translational modification, mediates important cellular functions including endocytic transport of molecules. Kaposi's sarcoma-associated herpesvirus (KSHV) is a gammaherpesvirus linked to the development of Kaposi's sarcoma, an endothelial malignancy commonly found in AIDS patients, and several other malignancies. KSHV enters endothelial cells primarily through clathrin-mediated endocytosis. In this study, we show that the proteasome activity is required for KSHV entry into endothelial cells and intracellular trafficking to nuclei. Inhibition of proteasome activity reduced KSHV infectivity and led to the accumulation of KSHV particles in EEA1+ early endosomal vesicles. Furthermore, we show that ubiquitination mediates the internalization of both KSHV and one of its receptors integrin β1. KSHV particles are colocalized with ubiquitin-binding proteins epsin and eps15, as well as activated forms of the E3 ligase c-Cbl. Knock-down of c-Cbl or inhibition of its phosphorylation blocked KSHV entry and trafficking, thus preventing KSHV infection of endothelial cells. Together, these results illustrate the essential role of ubiquitination during the internalization of KSHV and its cognate receptor integrin β1. The identification of an E3 ligase that mediates the ubiquitination of KSHV and its cognate receptor integrin β1 leading to viral entry provide a potential therapeutic target for this oncogenic virus.
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Affiliation(s)
- Whitney Greene
- Tumor Virology Program, Greehey Children's Cancer Research Institute, and Department of Pediatrics, University of Texas Health Science Center San Antonio, San Antonio, Texas, United States of America
| | - Wei Zhang
- Tumor Virology Program, Greehey Children's Cancer Research Institute, and Department of Pediatrics, University of Texas Health Science Center San Antonio, San Antonio, Texas, United States of America
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Meilan He
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Colleen Witt
- Department of Biology, College of Sciences, University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - Fengchun Ye
- Tumor Virology Program, Greehey Children's Cancer Research Institute, and Department of Pediatrics, University of Texas Health Science Center San Antonio, San Antonio, Texas, United States of America
| | - Shou-Jiang Gao
- Tumor Virology Program, Greehey Children's Cancer Research Institute, and Department of Pediatrics, University of Texas Health Science Center San Antonio, San Antonio, Texas, United States of America
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
- * E-mail:
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17
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Lee K, Shim J, Bae J, Kim YJ, Lee J. Stabilization of RNT-1 protein, runt-related transcription factor (RUNX) protein homolog of Caenorhabditis elegans, by oxidative stress through mitogen-activated protein kinase pathway. J Biol Chem 2012; 287:10444-10452. [PMID: 22308034 PMCID: PMC3323012 DOI: 10.1074/jbc.m111.314146] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 01/25/2012] [Indexed: 01/14/2023] Open
Abstract
RUNX proteins are evolutionarily conserved transcription factors known to be involved in various developmental processes. Here we report a new role for a RUNX protein: a role in stress response. We show that RNT-1, the Caenorhabditis elegans RUNX homolog, is constantly produced and degraded by the ubiquitination-proteasome pathway in the intestine of the nematode. RNT-1 was rapidly stabilized by oxidative stress, and the rnt-1-mutant animals were more sensitive to oxidative stress, indicating that rapid RNT-1 stabilization is a defense response against the oxidative stress. The MAP kinase pathway is required for RNT-1 stabilization, and RNT-1 was phosphorylated by SEK-1/PMK-1 in vitro. ChIP-sequencing analysis revealed a feedback loop mechanism of the MAP kinase pathway by the VHP-1 phosphatase in the RNT-1-mediated oxidative stress response. We propose that rnt-1 is regulated at the protein level for its role in the immediate response to environmental challenges in the intestine.
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Affiliation(s)
- Kiho Lee
- Research Center for Cellulomics, Department of Biological Sciences, World Class University (WCU) Department of Biophysics and Chemical Biology, Seoul National University, Seoul, 151-742, South Korea and
| | - Jiwon Shim
- Research Center for Cellulomics, Department of Biological Sciences, World Class University (WCU) Department of Biophysics and Chemical Biology, Seoul National University, Seoul, 151-742, South Korea and
| | - Jaebum Bae
- Department of Biochemistry, College of Life Science and Technology, Yonsei University, Seoul 120-749, South Korea
| | - Young-Joon Kim
- Department of Biochemistry, College of Life Science and Technology, Yonsei University, Seoul 120-749, South Korea
| | - Junho Lee
- Research Center for Cellulomics, Department of Biological Sciences, World Class University (WCU) Department of Biophysics and Chemical Biology, Seoul National University, Seoul, 151-742, South Korea and.
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18
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van den Boorn JG, Melief CJ, Luiten RM. Monobenzone-induced depigmentation: from enzymatic blockade to autoimmunity. Pigment Cell Melanoma Res 2011; 24:673-9. [PMID: 21689385 DOI: 10.1111/j.1755-148x.2011.00878.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Autoimmune side-effects such as vitiligo regularly occur during melanoma immunotherapy. As vitiligo development is associated with a superior prognosis, the active induction of vitiligo in melanoma patients can be a useful tactic. The potent skin-depigmenting agent monobenzone can be used successfully for this purpose. However, until recently, the mechanism of action behind monobenzone-induced skin depigmentation was unclear. Lately, the mechanistic basis for the augmented immunogenicity of monobenzone-exposed pigmented cells has been unveiled, and their active role in the induction of autoimmune T-cell-mediated vitiligo has become apparent. Here, we provide an immunological framework in which we condense this knowledge to an integrated theory of the generation of monobenzone-induced vitiligo.
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Affiliation(s)
- Jasper G van den Boorn
- Institute for Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany.
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19
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Bianco SDC, Vandepas L, Correa-Medina M, Gereben B, Mukherjee A, Kuohung W, Carroll R, Teles MG, Latronico AC, Kaiser UB. KISS1R intracellular trafficking and degradation: effect of the Arg386Pro disease-associated mutation. Endocrinology 2011; 152:1616-26. [PMID: 21285314 PMCID: PMC3060635 DOI: 10.1210/en.2010-0903] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The goal of this study was to investigate how the Arg386Pro mutation prolongs KiSS-1 receptor (KISS1R) responsiveness to kisspeptin, contributing to human central precocious puberty. Confocal imaging showed colocalization of wild-type (WT) KISS1R with a membrane marker, which persisted for up to 5 h of stimulation. Conversely, no colocalization with a lysosome marker was detected. Also, overnight treatment with a lysosome inhibitor did not affect WT KISS1R protein, whereas overnight treatment with a proteasome inhibitor increased protein levels by 24-fold. WT and Arg386Pro KISS1R showed time-dependent internalization upon stimulation. However, both receptors were recycled back to the membrane. The Arg386Pro mutation did not affect the relative distribution of KISS1R in membrane and internalized fractions when compared to WT KISS1R for up to 120 min of stimulation, demonstrating that this mutation does not affect KISS1R trafficking rate. Nonetheless, total Arg386Pro KISS1R was substantially increased compared with WT after 120 min of kisspeptin stimulation. This net increase was eliminated by blockade of detection of recycled receptors, demonstrating that recycled receptors account for the increased responsiveness of this mutant to kisspeptin. We therefore conclude the following: 1) WT KISS1R is degraded by proteasomes rather than lysosomes; 2) WT and Arg386Pro KISS1R are internalized upon stimulation, but most of the internalized receptors are recycled back to the membrane rather than degraded; 3) the Arg386Pro mutation does not affect the rate of KISS1R trafficking--instead, it prolongs responsiveness to kisspeptin by decreasing KISS1R degradation, resulting in the net increase on mutant receptor recycled back to the plasma membrane.
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Affiliation(s)
- Suzy D C Bianco
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, USA.
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20
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Ravikumar B, Sarkar S, Davies JE, Futter M, Garcia-Arencibia M, Green-Thompson ZW, Jimenez-Sanchez M, Korolchuk VI, Lichtenberg M, Luo S, Massey DCO, Menzies FM, Moreau K, Narayanan U, Renna M, Siddiqi FH, Underwood BR, Winslow AR, Rubinsztein DC. Regulation of mammalian autophagy in physiology and pathophysiology. Physiol Rev 2010; 90:1383-435. [PMID: 20959619 DOI: 10.1152/physrev.00030.2009] [Citation(s) in RCA: 1317] [Impact Index Per Article: 94.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
(Macro)autophagy is a bulk degradation process that mediates the clearance of long-lived proteins and organelles. Autophagy is initiated by double-membraned structures, which engulf portions of cytoplasm. The resulting autophagosomes ultimately fuse with lysosomes, where their contents are degraded. Although the term autophagy was first used in 1963, the field has witnessed dramatic growth in the last 5 years, partly as a consequence of the discovery of key components of its cellular machinery. In this review we focus on mammalian autophagy, and we give an overview of the understanding of its machinery and the signaling cascades that regulate it. As recent studies have also shown that autophagy is critical in a range of normal human physiological processes, and defective autophagy is associated with diverse diseases, including neurodegeneration, lysosomal storage diseases, cancers, and Crohn's disease, we discuss the roles of autophagy in health and disease, while trying to critically evaluate if the coincidence between autophagy and these conditions is causal or an epiphenomenon. Finally, we consider the possibility of autophagy upregulation as a therapeutic approach for various conditions.
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Affiliation(s)
- Brinda Ravikumar
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, Addenbrooke’s Hospital, Cambridge, United Kingdom
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21
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IL-7 induces rapid clathrin-mediated internalization and JAK3-dependent degradation of IL-7Ralpha in T cells. Blood 2010; 115:3269-77. [PMID: 20190194 DOI: 10.1182/blood-2009-10-246876] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Interleukin-7 (IL-7) is an essential cytokine for T-cell development and homeostasis. It is well established that IL-7 promotes the transcriptional down-regulation of IL7RA, leading to decreased IL-7Ralpha surface expression. However, it is currently unknown whether IL-7 regulates the intracellular trafficking and early turnover of its receptor on ligand binding. Here, we show that, in steady-state T cells, IL-7Ralpha is slowly internalized and degraded while a significant fraction recycles back to the surface. On IL-7 stimulation, there is rapid IL-7Ralpha endocytosis via clathrin-coated pits, decreased receptor recycling, and accelerated lysosome and proteasome-dependent degradation. In accordance, the half-life of IL-7Ralpha decreases from 24 hours to approximately 3 hours after IL-7 treatment. Interestingly, we further demonstrate that clathrin-dependent endocytosis is necessary for efficient IL-7 signal transduction. In turn, pretreatment of T cells with JAK3 or pan-JAK inhibitors suggests that IL-7Ralpha degradation depends on the activation of the IL-7 signaling effector JAK3. Overall, our findings indicate that IL-7 triggers rapid IL-7Ralpha endocytosis, which is required for IL-7-mediated signaling and subsequent receptor degradation.
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22
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Harris S, Lang SM, Means RE. Characterization of the rhesus fibromatosis herpesvirus MARCH family member rfK3. Virology 2010; 398:214-23. [PMID: 20060556 DOI: 10.1016/j.virol.2009.12.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 09/09/2009] [Accepted: 12/05/2009] [Indexed: 01/26/2023]
Abstract
Retroperitoneal fibromatosis-associated herpesvirus (RFHV) is a gamma-herpesvirus of macaques that is closely related to Kaposi's sarcoma-associated herpesvirus (KSHV). Herein, we present characterization of the K3 gene from RFHV, a homologue of the KSHV K3 and K5 genes. Like the KSHV proteins, kK3 and kK5, the rfK3 protein decreases cell surface MHC I levels. Similar to kK5, rfK3 also modulates ICAM-1, but not another kK5 target, B7.2. Inhibitors of dynamin or mutations in the rfK3 RING-CH E3 ubiquitin ligase domain block cellular target regulation, implicating a ubiquitin-dependent, endocytosis-mediated mechanism for target down regulation and degradation. Overall, this manuscript presents the first characterization of a non-human primate virus MARCH family E3 ubiquitin ligase contributing important information about the evolution of immune avoidance strategies in primate viruses and paving the way for an animal model examining the importance of kK3 and kK5 in vivo.
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Affiliation(s)
- Samyka Harris
- Howard University College of Medicine, Washington, DC 20059, USA
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23
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Leithe E, Kjenseth A, Sirnes S, Stenmark H, Brech A, Rivedal E. Ubiquitylation of the gap junction protein connexin-43 signals its trafficking from early endosomes to lysosomes in a process mediated by Hrs and Tsg101. J Cell Sci 2009; 122:3883-93. [PMID: 19808888 DOI: 10.1242/jcs.053801] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Gap junctions are dynamic plasma membrane domains, and their protein constituents, the connexins, have a high turnover rate in most tissue types. However, the molecular mechanisms involved in degradation of gap junctions have remained largely unknown. Here, we show that ubiquitin is strongly relocalized to connexin-43 (Cx43; also known as Gja1) gap junction plaques in response to activation of protein kinase C. Cx43 remained ubiquitylated during its transition to a Triton X-100-soluble state and along its trafficking to early endosomes. Following internalization, Cx43 partly colocalized with the ubiquitin-binding proteins Hrs (hepatocyte growth factor-regulated tyrosine kinase substrate; also known as Hgs) and Tsg101 (tumor susceptibility gene 101). Depletion of Hrs or Tsg101 by small interfering RNA abrogated trafficking of Cx43 from early endosomes to lysosomes. Under these conditions, Cx43 was able to undergo dephosphorylation and deubiquitylation, locate to the plasma membrane and form functional gap junctions. Simultaneous depletion of Hrs and Tsg101 caused accumulation of a phosphorylated and ubiquitylated subpopulation of Cx43 in early endosomes and in hybrid organelles between partly degraded annular gap junctions and endosomes. Collectively, these data reveal a central role of early endosomes in sorting of ubiquitylated Cx43, and identify Hrs and Tsg101 as crucial regulators of trafficking of Cx43 to lysosomes.
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Affiliation(s)
- Edward Leithe
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo and Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Montebello, Oslo, Norway.
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24
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Malardé V, Proust R, Dautry-Varsat A, Gesbert F. NEDD4-2 associates with gamma(c) and regulates its degradation rate. Biochem Biophys Res Commun 2009; 387:409-13. [PMID: 19615332 DOI: 10.1016/j.bbrc.2009.07.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Accepted: 07/12/2009] [Indexed: 11/26/2022]
Abstract
Interleukin-2 (IL-2) is a cytokine that regulates proliferation, differentiation and survival of various lymphoid cell subsets. Its actions are mediated through its binding to the IL-2 receptor which is composed of three subunits (IL-2Ralpha, IL-2Rbeta and gamma(c)). Only beta and gamma(c) have been shown to transduce intra cellular signals. The gamma(c) chain is shared by the interleukin-2, 4, 7, 9, 15 and 21 receptors, and is essential for lymphocyte functions. The regulation of gamma(c) expression level is therefore critical for the ability of cells to respond to these cytokines. In the present work, we show that the IL-2R constitutively associates with the ubiquitin ligase NEDD4-2, and to a lesser extent NEDD4-1. We identified the specific binding site on gamma(c). And we show that the loss of NEDD4 association on gamma(c) is accompanied by a dramatic increase of the half-life of the receptor subunit.
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Affiliation(s)
- Valérie Malardé
- Institut Pasteur, Unité de Biologie des Interactions Cellulaires, URA CNRS-2582, 75015 Paris, France
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25
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Schulman BA, Harper JW. Ubiquitin-like protein activation by E1 enzymes: the apex for downstream signalling pathways. Nat Rev Mol Cell Biol 2009; 10:319-31. [PMID: 19352404 PMCID: PMC2712597 DOI: 10.1038/nrm2673] [Citation(s) in RCA: 634] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Attachment of ubiquitin or ubiquitin-like proteins (known as UBLs) to their targets through multienzyme cascades is a central mechanism to modulate protein functions. This process is initiated by a family of mechanistically and structurally related E1 (or activating) enzymes. These activate UBLs through carboxy-terminal adenylation and thiol transfer, and coordinate the use of UBLs in specific downstream pathways by charging cognate E2 (or conjugating) enzymes, which then interact with the downstream ubiquitylation machinery to coordinate the modification of the target. A broad understanding of how E1 enzymes activate UBLs and how they selectively coordinate UBLs with downstream function has come from enzymatic, structural and genetic studies.
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Affiliation(s)
- Brenda A. Schulman
- Howard Hughes Medical Institute, Departments of Structural Biology, and Genetics and Tumor Cell Biology, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105
| | - J. Wade Harper
- Department of Pathology, Harvard Medical School, 77 Ave Louis Pasteur, Boston, MA 02115
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26
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Rangaraju S, Hankins D, Madorsky I, Madorsky E, Lee WH, Carter CS, Leeuwenburgh C, Notterpek L. Molecular architecture of myelinated peripheral nerves is supported by calorie restriction with aging. Aging Cell 2009; 8:178-91. [PMID: 19239416 DOI: 10.1111/j.1474-9726.2009.00460.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Peripheral nerves from aged animals exhibit features of degeneration, including marked fiber loss, morphological irregularities in myelinated axons and notable reduction in the expression of myelin proteins. To investigate how protein homeostatic mechanisms change with age within the peripheral nervous system, we isolated Schwann cells from the sciatic nerves of young and old rats. The responsiveness of cells from aged nerves to stress stimuli is weakened, which in part may account for the observed age-associated alterations in glial and axonal proteins in vivo. Although calorie restriction is known to slow the aging process in the central nervous system, its influence on peripheral nerves has not been investigated in detail. To determine if dietary restriction is beneficial for peripheral nerve health and glial function, we studied sciatic nerves from rats of four distinct ages (8, 18, 29 and 38 months) kept on an ad libitum (AL) or a 40% calorie restricted diet. Age-associated reduction in the expression of the major myelin proteins and widening of the nodes of Ranvier are attenuated by the dietary intervention, which is paralleled with the maintenance of a differentiated Schwann cell phenotype. The improvements in nerve architecture with diet restriction, in part, are underlined by sustained expression of protein chaperones and markers of the autophagy-lysosomal pathway. Together, the in vitro and in vivo results suggest that there might be an age-limit by which dietary intervention needs to be initiated to elicit a beneficial response on peripheral nerve health.
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Affiliation(s)
- Sunitha Rangaraju
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32610-0244, USA
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27
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Nam S, Min K, Hwang H, Lee HO, Lee JH, Yoon J, Lee H, Park S, Lee J. Control of rapsyn stability by the CUL-3-containing E3 ligase complex. J Biol Chem 2009; 284:8195-206. [PMID: 19158078 PMCID: PMC3282941 DOI: 10.1074/jbc.m808230200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Revised: 01/13/2009] [Indexed: 11/06/2022] Open
Abstract
Rapsyn is a postsynaptic protein required for clustering of nicotinic acetylcholine receptors (nAChRs) at the neuromuscular junction. Here we report the mechanism for posttranslational control of rapsyn protein stability. We confirmed that C18H9.7-encoded RPY-1 is a rapsyn homolog in Caenorhabditis elegans by showing that human rapsyn rescued rpy-1 mutant phenotypes in nematodes, as determined by levamisole assays and micropost array behavioral assays. We found that RPY-1 was degraded in the absence of functional UNC-29, a non-alpha subunit of the receptor, in an allele-specific manner, but not in the absence of other receptor subunits. The cytoplasmic loop of UNC-29 was found to be critical for RPY-1 stability. Through RNA interference screening, we found that UBC-1, UBC-12, NEDD-8, and RBX-1 were required for degradation of RPY-1. We identified cullin (CUL)-3 as a component of E3 ligase and KEL-8 as the substrate adaptor of RPY-1. Mammalian rapsyn was ubiquitinated by the CUL3/KLHL8-containing E3 ligase in vitro, and the knockdown of KLHL-8, a mammalian KEL-8 homolog, inhibited rapsyn ubiquitination in vivo, implying evolutionary conservation of the rapsyn stability control machinery. kel-8 suppression and rpy-1 overexpression in C. elegans produced a phenotype similar to that of a loss-of-function mutation of rpy-1, suggesting that control of rapsyn abundance is important for proper function of the receptor. Our results suggest a link between the control of rapsyn abundance and congenital myasthenic syndromes.
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Affiliation(s)
- Seunghee Nam
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
| | - Kyoengwoo Min
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
| | - Hyejin Hwang
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
| | - Hae-ock Lee
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
| | - Jung Hwa Lee
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
| | - Jongbok Yoon
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
| | - Hyunsook Lee
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
| | - Sungsu Park
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
| | - Junho Lee
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
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28
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Calistri A, Salata C, Parolin C, Palù G. Role of multivesicular bodies and their components in the egress of enveloped RNA viruses. Rev Med Virol 2009; 19:31-45. [PMID: 18618839 DOI: 10.1002/rmv.588] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
As an enveloped virus buds, the nascent viral capsid becomes wrapped in a plasma membrane-derived lipid envelope, and a membrane fission event is thus necessary to separate the virion from the host cell. This membrane fission event is well characterised in the case of enveloped RNA viruses, where it is promoted by late assembly domains (L-domains) present at the level of specific viral structural proteins. Research conducted over the past 10 years has demonstrated that L-domains represent docking sites for cellular proteins essential for the biogenesis of a cellular organelle, the multivesicular body (MVB). In this way, enveloped RNA viruses hijack the MVB components to the cellular site where the budding is executed. This review will focus on the cellular machinery exploited by enveloped RNA viruses in order to be released from infected cells. The role of ubiquitin and lipids in viral budding will also be discussed.
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Affiliation(s)
- A Calistri
- Department of Histology, Microbiology and Medical Biotechnologies, University of Padova, Padova, Italy
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29
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Ai J, Druhan LJ, Loveland MJ, Avalos BR. G-CSFR ubiquitination critically regulates myeloid cell survival and proliferation. PLoS One 2008; 3:e3422. [PMID: 18923646 PMCID: PMC2561048 DOI: 10.1371/journal.pone.0003422] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Accepted: 09/22/2008] [Indexed: 12/22/2022] Open
Abstract
The granulocyte colony-stimulating factor receptor (G-CSFR) is a critical regulator of granulopoiesis. Mutations in the G-CSFR in patients with severe congenital neutropenia (SCN) transforming to acute myelogenous leukemia (AML) have been shown to induce hypersensitivity and enhanced growth responses to G-CSF. Recent studies have demonstrated the importance of the ubiquitin/proteasome system in the initiation of negative signaling by the G-CSFR. To further investigate the role of ubiquitination in regulating G-CSFR signaling, we generated a mutant form of the G-CSFR (K762R/G-CSFR) which abrogates the attachment of ubiquitin to the lysine residue at position 762 of the G-CSFR that is deleted in the Δ716 G-CSFR form isolated from patients with SCN/AML. In response to G-CSF, mono-/polyubiquitination of the G-CSFR was impaired in cells expressing the mutant K762R/G-CSFR compared to cells transfected with the WT G-CSFR. Cells stably transfected with the K762R/G-CSFR displayed a higher proliferation rate, increased sensitivity to G-CSF, and enhanced survival following cytokine depletion, similar to previously published data with the Δ716 G-CSFR mutant. Activation of the signaling molecules Stat5 and Akt were also increased in K762R/G-CSFR transfected cells in response to G-CSF, and their activation remained prolonged after G-CSF withdrawal. These results indicate that ubiquitination is required for regulation of G-CSFR-mediated proliferation and cell survival. Mutations that disrupt G-CSFR ubiquitination at lysine 762 induce aberrant receptor signaling and hyperproliferative responses to G-CSF, which may contribute to leukemic transformation.
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Affiliation(s)
- Jing Ai
- Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio, United States of America
| | - Lawrence J. Druhan
- Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio, United States of America
| | - Megan J. Loveland
- Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio, United States of America
| | - Belinda R. Avalos
- Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio, United States of America
- Division of Hematology/Oncology, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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30
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Winslow AR, Rubinsztein DC. Autophagy in neurodegeneration and development. Biochim Biophys Acta Mol Basis Dis 2008; 1782:723-9. [PMID: 18644437 PMCID: PMC2597715 DOI: 10.1016/j.bbadis.2008.06.010] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Revised: 06/09/2008] [Accepted: 06/23/2008] [Indexed: 12/12/2022]
Abstract
Efficient protein turnover is essential for the maintenance of cellular health. Here we review how autophagy has fundamental functions in cellular homeostasis and possible uses as a therapeutic strategy for neurodegenerative diseases associated with intracytosolic aggregate formation, like Huntington's disease (HD). Drugs like rapamycin, that induce autophagy, increase the clearance of mutant huntingtin fragments and ameliorate the pathology in cell and animal models of HD and related conditions. In Drosophila, the beneficial effects of rapamycin in diseases related to HD are autophagy-dependent. We will also discuss the importance of autophagy in early stages of development and its possible contribution as a secondary disease mechanism in forms of fronto-temporal dementias, motor neuron disease, and lysosomal storage disorders.
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Affiliation(s)
- Ashley R Winslow
- Department of Medical Genetics, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0XY, UK
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31
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Kindwall-Keller TL, Druhan LJ, Ai J, Hunter MG, Massullo P, Loveland M, Avalos BR. Role of the proteasome in modulating native G-CSFR expression. Cytokine 2008; 43:114-23. [PMID: 18554923 DOI: 10.1016/j.cyto.2008.04.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Revised: 04/18/2008] [Accepted: 04/28/2008] [Indexed: 11/26/2022]
Abstract
The granulocyte colony-stimulating factor receptor (G-CSFR) is a critical regulator of granulopoiesis, but the mechanisms controlling its surface expression are poorly understood. Recent studies using transfected cell lines have suggested the activated G-CSFR is routed to the lysosome and not the proteasome. Here, we examined the role of the ubiquitin/proteasome system in regulating G-CSFR surface expression in both ts20 cells that have a temperature-sensitive E1 ubiquitin-activating enzyme and in primary human neutrophils. We show that the G-CSFR is constitutively ubiquitinated, which increases following ligand binding. In the absence of a functional E1 enzyme, ligand-induced internalization of the receptor is inhibited. Pre-treatment of ts20 transfectants with either chloroquine or MG132 inhibited ligand-induced G-CSFR degradation, suggesting a role for both lysosomes and proteasomes in regulating G-CSFR surface expression in this cell line. In neutrophils, inhibition of the proteasome but not the lysosome was found to inhibit internalization/degradation of the activated G-CSFR. Collectively, these data demonstrate the requirement for a functional ubiquitin/proteasome system in G-CSFR internalization and degradation. Our results suggest a prominent role for the proteasome in physiologic modulation of the G-CSFR, and provide further evidence for the importance of the ubiquitin/proteasome system in the initiation of negative signaling by cytokine receptors.
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Affiliation(s)
- Tamila L Kindwall-Keller
- Department of Medicine, Comprehensive Cancer Center of Case Western Reserve University and University Hospitals of Cleveland, Cleveland, OH, USA
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32
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Yamashita Y, Kojima K, Tsukahara T, Agawa H, Yamada K, Amano Y, Kurotori N, Tanaka N, Sugamura K, Takeshita T. Ubiquitin-independent binding of Hrs mediates endosomal sorting of the interleukin-2 receptor beta-chain. J Cell Sci 2008; 121:1727-38. [PMID: 18445679 DOI: 10.1242/jcs.024455] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Several lines of evidence have revealed that ubiquitylation of membrane proteins serves as a signal for endosomal sorting into lysosomes or lytic vacuoles. The hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) interacts with ubiquitylated cargoes through its ubiquitin-interacting-motif domain (UIM domain), and plays an essential early role in endosomal sorting. Here, we show that the C-terminal region of Hrs, which does not contain the UIM domain, can bind to interleukin-2 receptor beta (IL-2Rbeta). We found a direct interaction between bacterially expressed IL-2Rbeta and Hrs in GST pull-down assays, indicating that their binding is independent of ubiquitin. Trafficking and degradation assays revealed that, similarly to wild-type IL-2Rbeta, an IL-2Rbeta mutant lacking all the cytoplasmic lysine residues is sorted from Hrs-positive early endosomes to LAMP1-positive late endosomes, resulting in degradation of the receptor. By contrast, an IL-2Rbeta mutant lacking the Hrs-binding region passes through early endosomes and is mis-sorted to compartments positive for the transferrin receptor. The latter mutant exhibits attenuated degradation. Taken together, these results indicate that precise sorting of IL-2Rbeta from early to late endosomes is mediated by Hrs, a known sorting component of the ubiquitin-dependent machinery, in a manner that is independent of UIM-ubiquitin binding.
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Affiliation(s)
- Yuki Yamashita
- Department of Microbiology and Immunology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan
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Geetha T, Wooten MW. TrkA receptor endolysosomal degradation is both ubiquitin and proteasome dependent. Traffic 2008; 9:1146-56. [PMID: 18419753 DOI: 10.1111/j.1600-0854.2008.00751.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Gaps in our knowledge exist regarding the degradation of the tropomyosin-regulated kinase A (TrkA) receptor after addition of neurotrophin, nerve growth factor (NGF). TrkA is rapidly and transiently ubiquitinated upon addition of NGF. Here, we demonstrate that the polyubiquitin tag plays a definitive role in receptor sorting. Treatment of PC12 cells with lactacystin prevented NGF-dependent deubiquitination and degradation of TrkA. However, treatment with methylamine, bafilomycin or leupeptin, did not prevent NGF-dependent deubiquitination but blocked the degradation of TrkA. Employing co-immunoprecipitation, biochemical fractionation and confocal microscopy, the kinetics of receptor trafficking post-internalization was observed to occur as a sequel from endosome/multivesicular body, proteasomes, culminating with degradation in the lysosomes. The trafficking of the polyubiquitin-deficient TrkA receptor mutant K485R was impaired and likewise failed to degrade revealing that the receptor escapes degradation. The interaction of TrkA with proteasomes was confirmed by purification and co-immunoprecipitation. We provide evidence that proteasomal deubiquitinating enzymes trim K63-ubiquitin chains from the TrkA receptor prior to its delivery to lysosomes for degradation. Taken together, our results reveal the existence of a novel proteasome-dependent step in receptor degradation.
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Affiliation(s)
- Thangiah Geetha
- Department of Biological Sciences, Program in Cellular and Molecular Biosciences, Auburn University, Auburn, AL 36849, USA
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Kwon SH, Pollard H, Guggino WB. Knockdown of NHERF1 enhances degradation of temperature rescued DeltaF508 CFTR from the cell surface of human airway cells. Cell Physiol Biochem 2007; 20:763-72. [PMID: 17982258 DOI: 10.1159/000110436] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2007] [Indexed: 11/19/2022] Open
Abstract
DeltaF508 CFTR can be functionally restored in the plasma membrane by exposure of the cell to lower temperature. However, restored DeltaF508 CFTR has a much shorter half-life than normal. We studied whether NHERF1, which binds to the PDZ motif of CFTR, might be a critical mediator in the turnover of DeltaF508 CFTR from the cell surface. We used RNAi to reduce the expression of NHERF1 in human airway epithelial cells. Knockdown of NHERF1 reversibly reduces surface expression of WT-CFTR without altering its total expression. As expected, temperature correction increased mature C band DeltaF508 CFTR (rDeltaF508) but unexpectedly allowed immature B band of rDeltaF508 to traffic to the cell surface. Both surface and total expression of rDeltaF508 in NHERF1 knockdown cells were reduced and degradation of surface localized rDeltaF508 was even faster in NHERF1 knockdown cells. Proteasomal and lysosomal inhibitor treatments led to a significant decrease in the accelerated degradation of surface rDeltaF508 in NHERF1 knockdown cells. These results indicate that NHERF1 plays a role in the turnover of CFTR at the cell surface, and that rDeltaF508 CFTR at the cell surface remains highly susceptible to degradation.
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Affiliation(s)
- Sang-Ho Kwon
- Department of Physiology, School of Medicine, The Johns Hopkins University, Baltimore, MD 21205, USA
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Abstract
The two major cellular sites for membrane protein degradation are the proteasome and the lysosome. Ubiquitin attachment is a sorting signal for both degradation routes. For lysosomal degradation, ubiquitination triggers the sorting of cargo proteins into the lumen of late endosomal multivesicular bodies (MVBs)/endosomes. MVB formation occurs when a portion of the limiting membrane of an endosome invaginates and buds into its own lumen. Intralumenal vesicles are degraded when MVBs fuse to lysosomes. The proper delivery of proteins to the MVB interior relies on specific ubiquitination of cargo, recognition and sorting of ubiquitinated cargo to endosomal subdomains, and the formation and scission of cargo-filled intralumenal vesicles. Over the past five years, a number of proteins that may directly participate in these aspects of MVB function and biogenesis have been identified. However, major questions remain as to exactly what these proteins do at the molecular level and how they may accomplish these tasks.
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Affiliation(s)
- Robert C. Piper
- Department of Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242
| | - David J. Katzmann
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55095
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Lu Z, Je HS, Young P, Gross J, Lu B, Feng G. Regulation of synaptic growth and maturation by a synapse-associated E3 ubiquitin ligase at the neuromuscular junction. ACTA ACUST UNITED AC 2007; 177:1077-89. [PMID: 17576800 PMCID: PMC2064367 DOI: 10.1083/jcb.200610060] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ubiquitin–proteasome pathway has been implicated in synaptic development and plasticity. However, mechanisms by which ubiquitination contributes to precise and dynamic control of synaptic development and plasticity are poorly understood. We have identified a PDZ domain containing RING finger 3 (PDZRN3) as a synapse-associated E3 ubiquitin ligase and have demonstrated that it regulates the surface expression of muscle-specific receptor tyrosine kinase (MuSK), the key organizer of postsynaptic development at the mammalian neuromuscular junction. PDZRN3 binds to MuSK and promotes its ubiquitination. Regulation of cell surface levels of MuSK by PDZRN3 requires the ubiquitin ligase domain and is mediated by accelerated endocytosis. Gain- and loss-of-function studies in cultured myotubes show that regulation of MuSK by PDZRN3 plays an important role in MuSK-mediated nicotinic acetylcholine receptor clustering. Furthermore, overexpression of PDZRN3 in skeletal muscle of transgenic mice perturbs the growth and maturation of the neuromuscular junction. These results identify a synapse-associated E3 ubiquitin ligase as an important regulator of MuSK signaling.
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Affiliation(s)
- Zhonghua Lu
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
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37
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Sehat B, Andersson S, Vasilcanu R, Girnita L, Larsson O. Role of ubiquitination in IGF-1 receptor signaling and degradation. PLoS One 2007; 2:e340. [PMID: 17406664 PMCID: PMC1838569 DOI: 10.1371/journal.pone.0000340] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2006] [Accepted: 03/12/2007] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The insulin-like growth factor 1 receptor (IGF-1R) plays numerous crucial roles in cancer biology. The majority of knowledge on IGF-1R signaling is concerned with its role in the activation of the canonical phosphatidyl inositol-3 kinase (PI3K)/Akt and MAPK/ERK pathways. However, the role of IGF-1R ubiquitination in modulating IGF-1R function is an area of current research. In light of this we sought to determine the relationship between IGF-1R phosphorylation, ubiquitination, and modulation of growth signals. METHODOLOGY Wild type and mutant constructs of IGF-1R were transfected into IGF-1R null fibroblasts. IGF-1R autophosphorylation and ubiquitination were determined by immunoprecipitation and western blotting. IGF-1R degradation and stability was determined by cyclohexamide-chase assay in combination with lysosome and proteasome inhibitors. PRINCIPAL FINDINGS IGF-1R autophosphorylation was found to be an absolute requirement for receptor ubiquitination. Deletion of C-terminal domain had minimal effect on IGF-1 induced receptor autophosphorylation, however, ubiquitination and ERK activation were completely abolished. Cells expressing kinase impaired IGF-1R, exhibited both receptor ubiquitination and ERK phosphorylation, however failed to activate Akt. While IGF-1R mutants with impaired PI3K/Akt signaling were degraded mainly by the proteasomes, the C-terminal truncated one was exclusively degraded through the lysosomal pathway. CONCLUSIONS Our data suggest important roles of ubiquitination in mediating IGF-1R signaling and degradation. Ubiquitination of IGF-1R requires receptor tyrosine kinase activity, but is not involved in Akt activation. In addition we show that the C-terminal domain of IGF-1R is a necessary requisite for ubiquitination and ERK phosphorylation as well as for proteasomal degradation of the receptor.
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Affiliation(s)
- Bita Sehat
- Department of Oncology and Pathology, Cancer Centre Karolinska (CCK), Karolinska Institutet and Karolinska University Hospital-Solna, Stockholm, Sweden
| | - Sandra Andersson
- Department of Oncology and Pathology, Cancer Centre Karolinska (CCK), Karolinska Institutet and Karolinska University Hospital-Solna, Stockholm, Sweden
| | - Radu Vasilcanu
- Department of Oncology and Pathology, Cancer Centre Karolinska (CCK), Karolinska Institutet and Karolinska University Hospital-Solna, Stockholm, Sweden
| | - Leonard Girnita
- Department of Oncology and Pathology, Cancer Centre Karolinska (CCK), Karolinska Institutet and Karolinska University Hospital-Solna, Stockholm, Sweden
| | - Olle Larsson
- Department of Oncology and Pathology, Cancer Centre Karolinska (CCK), Karolinska Institutet and Karolinska University Hospital-Solna, Stockholm, Sweden
- * To whom correspondence should be addressed. E-mail:
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38
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Pak Y, Glowacka WK, Bruce MC, Pham N, Rotin D. Transport of LAPTM5 to lysosomes requires association with the ubiquitin ligase Nedd4, but not LAPTM5 ubiquitination. ACTA ACUST UNITED AC 2007; 175:631-45. [PMID: 17116753 PMCID: PMC2064599 DOI: 10.1083/jcb.200603001] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
LAPTM5 is a lysosomal transmembrane protein expressed in immune cells. We show that LAPTM5 binds the ubiquitin-ligase Nedd4 and GGA3 to promote LAPTM5 sorting from the Golgi to the lysosome, an event that is independent of LAPTM5 ubiquitination. LAPTM5 contains three PY motifs (L/PPxY), which bind Nedd4-WW domains, and a ubiquitin-interacting motif (UIM) motif. The Nedd4-LAPTM5 complex recruits ubiquitinated GGA3, which binds the LAPTM5-UIM; this interaction does not require the GGA3-GAT domain. LAPTM5 mutated in its Nedd4-binding sites (PY motifs) or its UIM is retained in the Golgi, as is LAPTM5 expressed in cells in which Nedd4 or GGA3 is knocked-down with RNAi. However, ubiquitination-impaired LAPTM5 can still traffic to the lysosome, suggesting that Nedd4 binding to LAPTM5, not LAPTM5 ubiquitination, is required for targeting. Interestingly, Nedd4 is also able to ubiquitinate GGA3. These results demonstrate a novel mechanism by which the ubiquitin-ligase Nedd4, via interactions with GGA3 and cargo (LAPTM5), regulates cargo trafficking to the lysosome without requiring cargo ubiquitination.
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Affiliation(s)
- Youngshil Pak
- Program in Cell Biology, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada, M5G 1X8
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Marijanovic Z, Ragimbeau J, Kumar K, Fuchs S, Pellegrini S. TYK2 activity promotes ligand-induced IFNAR1 proteolysis. Biochem J 2006; 397:31-8. [PMID: 16551269 PMCID: PMC1479745 DOI: 10.1042/bj20060272] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The type I IFNR (interferon receptor) is a heterodimer composed of two transmembrane chains, IFNAR1 (interferon-alpha receptor 1 subunit) and IFNAR2, which are associated with the tyrosine kinases Tyk2 and Jak1 (Janus kinase 1) respectively. Ligand-induced down-regulation of the type I IFNR is a major mechanism of negative regulation of cellular signalling and involves the internalization and lysosomal degradation of IFNAR1. IFNalpha promotes the phosphorylation of IFNAR1 on Ser535, followed by recruitment of the E3 ubiquitin ligase, beta-TrCP2 (beta-transducin repeats-containing protein 2), ubiquitination of IFNAR1 and proteolysis. The non-catalytic role of Tyk2 in sustaining the steady-state IFNAR1 level at the plasma membrane is well documented; however, little is known about the function of Tyk2 in the steps that precede and succeed serine phosphorylation and ubiquitination of IFNAR1 in response to ligand binding. In the present study, we show that catalytic activation of Tyk2 is not essential for IFNAR1 internalization, but is required for ligand-induced IFNAR1 serine phosphorylation, ubiquitination and efficient lysosomal proteolysis.
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Affiliation(s)
- Zrinka Marijanovic
- *Cytokine Signalling Unit, CNRS URA 1961, Pasteur Institute, Paris 75724, France
| | - Josiane Ragimbeau
- *Cytokine Signalling Unit, CNRS URA 1961, Pasteur Institute, Paris 75724, France
| | - K. G. Suresh Kumar
- †Department of Animal Biology, University of Pennsylvania, Philadelphia, PA 19104-6046, U.S.A
| | - Serge Y. Fuchs
- †Department of Animal Biology, University of Pennsylvania, Philadelphia, PA 19104-6046, U.S.A
| | - Sandra Pellegrini
- *Cytokine Signalling Unit, CNRS URA 1961, Pasteur Institute, Paris 75724, France
- To whom correspondence should be addressed (email )
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BIROS DJ, NAMBA K, TAYLOR AW. Alpha-MSH regulates protein ubiquitination in T cells. Cell Mol Biol (Noisy-le-grand) 2006; 52:33-8. [PMID: 16914084 PMCID: PMC4698146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2005] [Accepted: 05/31/2005] [Indexed: 05/11/2023]
Abstract
The neuropeptide alpha-melanocyte stimulating hormone (alpha-MSH) suppresses IFN-gamma + T cells from mice. We discovered, however, that despite this significant production by DTH-mediating effector CD4 supression of IFN-gamma production, alpha-MSH-treated effector T cells had the same level of IFN-gamma mRNA expression and intracellular IFN-gamma protein as untreated activated T cells. In order to explain why IFN-gamma production was suppressed in the face of unchanged mRNA and intracellular IFN-gamma levels, we looked for mechanisms that could increase the degradation of IFN-gamma within the alpha-MSH-treated T cells. Among the known pathways of post-translational intracellular protein modification, the ubiquitin-proteosome system was examined in alpha-MSH-treated T cells to see if a post-translational protein modification occurred to prevent IFN-gamma secretion from the cell. Immunoblots from alpha-MSH-treated T cells showed higher levels of protein ubiquitination when compared to untreated T cells. Resting T cells treated with alpha-MSH also demonstrated enhanced protein ubiquitination. We found that IFN-gamma is one of the ubiquitinated proteins in the alpha-MSH-treated activated T cells. Our results demonstrate that one of the mechanisms by which alpha-MSH regulates T cell activity is through mediating a change in the pattern of protein ubiquitination in T cells.
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Affiliation(s)
- D. J. BIROS
- The Schepens Eye Research Institute and the Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts U.S.A
| | - K. NAMBA
- Department of Ophthalmology and Visual Sciences, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - A. W. TAYLOR
- Schepens Eye Research Institutealpha, 20 Staniford Street, Boston, MA 02114, U.S.A; Phone: 617-912-7452; Fax: 617-912-0137
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Ivanov VN, Hei TK. Dual treatment with COX-2 inhibitor and sodium arsenite leads to induction of surface Fas Ligand expression and Fas-Ligand-mediated apoptosis in human melanoma cells. Exp Cell Res 2006; 312:1401-17. [PMID: 16487513 PMCID: PMC4376328 DOI: 10.1016/j.yexcr.2006.01.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Revised: 12/12/2005] [Accepted: 01/09/2006] [Indexed: 11/18/2022]
Abstract
Most human melanomas express Fas receptor on the cell surface, and treatment with exogenous Fas Ligand (FasL) efficiently induces apoptosis of these cells. In contrast, endogenous surface expression of FasL is suppressed in Fas-positive melanomas. We report here the use of a combination of sodium arsenite, an inhibitor of NF-kappaB activation, and NS398, a cyclooxygenase-2 (COX-2) inhibitor, for restoration of the surface FasL expression. We observed a large increase of Fas-mediated apoptosis in Fas-positive melanomas. This was due to induction of FasL surface expression and increased susceptibility to Fas death signaling after arsenite and NS398 treatment. Furthermore, silencing COX-2 expression by specific RNAi also effectively increased surface FasL expression following arsenite treatment. Upregulation of the surface FasL levels was based on an increase in the efficiency of translocation to the cell surface and stabilization of FasL protein on the cell surface, rather than on acceleration of the FasL gene transcription. Data obtained demonstrate that the combination of arsenite with inhibitors of COX-2 may affect the target cancer cells via induction of FasL-mediated death signaling.
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Affiliation(s)
- Vladimir N Ivanov
- Center for Radiological Research, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
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Belouzard S, Rouillé Y. Ubiquitylation of leptin receptor OB-Ra regulates its clathrin-mediated endocytosis. EMBO J 2006; 25:932-42. [PMID: 16482222 PMCID: PMC1409713 DOI: 10.1038/sj.emboj.7600989] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Accepted: 01/17/2006] [Indexed: 01/17/2023] Open
Abstract
Leptin receptors are constitutively endocytosed in a ligand-independent manner. To study their endocytosis, leptin receptors OB-Ra and OB-Rb were expressed in HeLa cells. Both receptor isoforms were ubiquitylated, internalized by clathrin-mediated endocytosis and transported to Hrs-positive endosomes after their internalization. Proteasome inhibitors inhibited OB-Ra but not OB-Rb internalization from the cell surface. OB-Ra ubiquitylation occurred on lysine residues K877 and K889 in the cytoplasmic tail, the mutation of which abolished OB-Ra internalization. Fusion of an ubiquitin molecule at the C-terminus of an OB-Ra construct defective both in ubiquitylation and endocytosis restored clathrin-dependent endocytosis of the receptor. The internalization of this constitutively mono-ubiquitylated construct was no longer sensitive to proteasome inhibitors, which inhibited OB-Ra endocytosis by blocking its ubiquitylation. Fusion of an ubiquitin molecule to a transferrin receptor deleted from its own endocytosis motif restored clathrin-mediated endocytosis. We propose that mono-ubiquitin conjugates act as internalization motifs for clathrin-dependent endocytosis of leptin receptor OB-Ra.
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Affiliation(s)
- Sandrine Belouzard
- Centre National de la Recherche Scientifique, Unité Propre de Recherche 2511, Institut Pasteur de Lille, Lille Cedex, France
| | - Yves Rouillé
- Centre National de la Recherche Scientifique, Unité Propre de Recherche 2511, Institut Pasteur de Lille, Lille Cedex, France
- Centre National de la Recherche Scientifique, Unité Propre de Recherche 2511, Institut Pasteur de Lille, 1 rue du Professeur Calmette, BP 447, 59021 Lille Cedex, France. E-mail:
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Gesbert F, Malardé V, Dautry-Varsat A. Ubiquitination of the common cytokine receptor gammac and regulation of expression by an ubiquitination/deubiquitination machinery. Biochem Biophys Res Commun 2005; 334:474-80. [PMID: 16004964 DOI: 10.1016/j.bbrc.2005.06.121] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Accepted: 06/15/2005] [Indexed: 10/25/2022]
Abstract
The common cytokine receptor gamma(c) is shared by the interleukin-2, -4, -7, -9, -15, and -21 receptors, and is essential for lymphocyte proliferation and survival. The regulation of gamma(c) receptor expression level is therefore critical for the ability of cells to respond to these cytokines. We previously reported that gamma(c) is efficiently constitutively internalized and addressed towards a degradation endocytic compartment. We show that gamma(c) is ubiquitinated and also associated to ubiquitinated proteins. We report that the ubiquitin-ligase c-Cbl induces gamma(c) down-regulation. In addition, the ubiquitin-hydrolase, DUB-2, counteracts the effect of c-Cbl on gamma(c) expression. We show that an increase in DUB-2 expression correlates with an increased gamma(c) half-life, resulting in the up-regulation of the receptor. Altogether, we show that gamma(c) is the target of an ubiquitination mechanism and its expression level can be regulated through the activities of a couple of ubiquitin-ligase/ubiquitin-hydrolase enzymes, namely c-Cbl/DUB-2.
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Affiliation(s)
- Franck Gesbert
- Unité de Biologie des Interactions Cellulaires, Institut Pasteur, CNRS URA 2582, 25-28 rue du Dr. Roux, 75724 Paris Cedex 15, France
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Lu JC, Piazza TM, Schuler LA. Proteasomes mediate prolactin-induced receptor down-regulation and fragment generation in breast cancer cells. J Biol Chem 2005; 280:33909-16. [PMID: 16103113 PMCID: PMC1976473 DOI: 10.1074/jbc.m508118200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Prolactin regulates a variety of physiological processes, including mammary gland growth and differentiation, and recent findings support an important role in breast cancer development and progression. However, little is known about the trafficking of its receptor, a member of the cytokine receptor superfamily. In the present study, we examined the effect of ligand on the endogenous "long" isoform of the prolactin receptor in breast cancer cells. We found that prolactin caused rapid and prolonged down-regulation of this receptor. The prolactin-induced increase in degradation was blocked by inhibitors of both proteasomes and lysosomes. However, the ubiquitin-conjugating system was not required for internalization. Prolactin also resulted in the concomitant appearance of a cell-associated prolactin receptor fragment containing the extracellular domain. This latter process required proteasomal, but not metalloprotease, activity, distinguishing it from ectodomain "shedding" of other membrane receptors, which are secreted as binding proteins. The prolactin receptor fragment was labeled by surface biotinylation and independent of protein synthesis. Together, these data indicated that prolactin binding initiates limited proteasomal cleavage of its receptor, generating a cell-associated fragment containing the extracellular domain. Our findings described a new potential mediator of prolactin action and a novel mechanism whereby proteasomes modulate cellular processes.
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Affiliation(s)
- Juu-Chin Lu
- From the Department of Comparative Biosciences
- Endocrinology-Reproductive Physiology Program, and
| | - Timothy M. Piazza
- From the Department of Comparative Biosciences
- Comparative Biomedical Sciences Program, University of Wisconsin-Madison, Wisconsin 53706
| | - Linda A. Schuler
- From the Department of Comparative Biosciences
- Endocrinology-Reproductive Physiology Program, and
- Comparative Biomedical Sciences Program, University of Wisconsin-Madison, Wisconsin 53706
- To whom correspondence should be addressed: Dept. of Comparative Biosciences, University of Wisconsin, 2015 Linden Dr., Madison, WI 53706. Tel.: 608-263-9825; Fax: 608-263-3926; E-mail:
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Abstract
The receptor for hepatocyte growth factor (HGF), Met, controls a programme of invasive growth that combines proliferation with various moto- and morphogenetic processes. This process is important for development and organ regeneration, but dysregulation in transformed tissues can contribute to cancer progression and metastasis. Acute stimulation of tissue culture cells with HGF leads to Met downregulation via degradation through an endocytic mechanism that also requires proteasome activity. Perturbation of Met trafficking on the endocytic pathway, either at the level of the internalisation step or during sorting at the early endosome, leads to altered signalling outputs. Ubiquitination of Met through the E3-ligase Cbl is required for receptor downregulation, and a mutant receptor defective in Cbl binding is able to transform cells. We discuss the hypothesis that some naturally occurring Met mutants implicated in cancer may transform cells owing to defects in their trafficking along the endosomal degradation pathway.
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Affiliation(s)
- D E Hammond
- Physiological Laboratory, University of Liverpool, Liverpool, UK
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Dupré S, Urban-Grimal D, Haguenauer-Tsapis R. Ubiquitin and endocytic internalization in yeast and animal cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2005; 1695:89-111. [PMID: 15571811 DOI: 10.1016/j.bbamcr.2004.09.024] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Endocytosis is involved in a wide variety of cellular processes, and the internalization step of endocytosis has been extensively studied in both lower and higher eukaryotic cells. Studies in mammalian cells have described several endocytic pathways, with the main emphasis on clathrin-dependent endocytosis. Genetic studies in yeast have underlined the critical role of actin and actin-binding proteins, lipid modification, and the ubiquitin conjugation system. The combined results of studies of endocytosis in higher and lower eukaryotic cells reveal an interesting interplay in the two systems, including a crucial role for ubiquitin-associated events. The ubiquitylation of yeast cell-surface proteins clearly acts as a signal triggering their internalization. Mammalian cells display variations on the common theme of ubiquitin-linked endocytosis, according to the cell-surface protein considered. Many plasma membrane channels, transporters and receptors undergo cell-surface ubiquitylation, required for the internalization or later endocytic steps of some cell-surface proteins, whereas for others, internalization involves interaction with the ubiquitin conjugation system or with ancillary proteins, which are themselves ubiquitylated. Epsins and Eps15 (or Eps15 homologs), are commonly involved in the process of endocytosis in all eukaryotes, their critical role in this process stemming from their capacity to bind ubiquitin, and to undergo ubiquitylation.
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Affiliation(s)
- S Dupré
- Institut Jacques Monod-CNRS Universités Paris VI and Paris VII, 2 place Jussieu 75005 Paris, France
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Walrafen P, Verdier F, Kadri Z, Chrétien S, Lacombe C, Mayeux P. Both proteasomes and lysosomes degrade the activated erythropoietin receptor. Blood 2005; 105:600-8. [PMID: 15358619 DOI: 10.1182/blood-2004-03-1216] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
AbstractActivation of the erythropoietin receptor (EpoR) after Epo binding is very transient because of the rapid activation of strong down-regulation mechanisms that quickly decrease Epo sensitivity of the cells. Among these down-regulation mechanisms, receptor internalization and degradation are probably the most efficient. Here, we show that the Epo receptor was rapidly ubiquitinated after ligand stimulation and that the C-terminal part of the Epo receptor was degraded by the proteasomes. Both ubiquitination and receptor degradation by the proteasomes occurred at the cell surface and required Janus kinase 2 (Jak2) activation. Moreover, Epo-EpoR complexes were rapidly internalized and targeted to the lysosomes for degradation. Neither Jak2 nor proteasome activities were required for internalization. In contrast, Jak2 activation was necessary for lysosome targeting of the Epo-EpoR complexes. Blocking Jak2 with the tyrphostin AG490 led to some recycling of internalized Epo-Epo receptor complexes to the cell surface. Thus, activated Epo receptors appear to be quickly degraded after ubiquitination by 2 proteolytic systems that proceed successively: the proteasomes remove part of the intracellular domain at the cell surface, and the lysosomes degrade the remaining part of the receptor-hormone complex. The efficiency of these processes probably explains the short duration of intracellular signaling activated by Epo.
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Affiliation(s)
- Pierre Walrafen
- Département d'Hématologie, Institut Cochin, Institut National de la Santé et de la Recherche Médicale U567, Paris, France
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Hryciw DH, Ekberg J, Lee A, Lensink IL, Kumar S, Guggino WB, Cook DI, Pollock CA, Poronnik P. Nedd4-2 Functionally Interacts with ClC-5. J Biol Chem 2004; 279:54996-5007. [PMID: 15489223 DOI: 10.1074/jbc.m411491200] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Constitutive albumin uptake by the proximal tubule is achieved by a receptor-mediated process in which the Cl(-) channel, ClC-5, plays an obligate role. Here we investigated the functional interaction between ClC-5 and ubiquitin ligases Nedd4 and Nedd4-2 and their role in albumin uptake in opossum kidney proximal tubule (OK) cells. In vivo immunoprecipitation using an anti-HECT antibody demonstrated that ClC-5 bound to ubiquitin ligases, whereas glutathione S-transferase pull-downs confirmed that the C terminus of ClC-5 bound both Nedd4 and Nedd4-2. Nedd4-2 alone was able to alter ClC-5 currents in Xenopus oocytes by decreasing cell surface expression of ClC-5. In OK cells, a physiological concentration of albumin (10 mug/ml) rapidly increased cell surface expression of ClC-5, which was also accompanied by the ubiquitination of ClC-5. Albumin uptake was reduced by inhibiting either the lysosome or proteasome. Total levels of Nedd4-2 and proteasome activity also increased rapidly in response to albumin. Overexpression of ligase defective Nedd4-2 or knockdown of endogenous Nedd4-2 with small interfering RNA resulted in significant decreases in albumin uptake. In contrast, pathophysiological concentrations of albumin (100 and 1000 mug/ml) reduced the levels of ClC-5 and Nedd4-2 and the activity of the proteasome to the levels seen in the absence of albumin. These data demonstrate that normal constitutive uptake of albumin by the proximal tubule requires Nedd4-2, which may act via ubiquitination to shunt ClC-5 into the endocytic pathway.
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Affiliation(s)
- Deanne H Hryciw
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
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Wiedemann A, Müller S, Favier B, Penna D, Guiraud M, Delmas C, Champagne E, Valitutti S. T-cell activation is accompanied by an ubiquitination process occurring at the immunological synapse. Immunol Lett 2004; 98:57-61. [PMID: 15790509 DOI: 10.1016/j.imlet.2004.10.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Revised: 10/05/2004] [Accepted: 10/18/2004] [Indexed: 11/19/2022]
Abstract
The immunological synapse (IS) is a specialized signaling area formed at the contact site between T-cells and antigen-presenting cells (APC), where sustained engagement and signaling of TCR and accessory molecules occur. A key feature of T-cell antigen recognition is that the process of TCR/peptide-MHC interaction is self-limited by the internalization and degradation of triggered TCR and recruited signaling components. The mechanism of signaling component degradation involves their ubiquitination and targeting for degradation. Yet, the relationship between the ubiquitination process and TCR signaling as well as the cellular localization of TCR-induced ubiquitination are still elusive. In the present work, we visualize for the first time ubiquitination at the TCR signaling area. We show an enrichment of ubiquitin staining in TCR/CD3 caps in T-lymphocytes stimulated by anti-CD3 antibodies. Remarkably, we also show the recruitment of the ubiquitin ligase Cbl-b and a significant ubiquitination at the immunological synapse in antigen-stimulated T-cells. Our results identify the immunological synapse as the cellular area where TCR-induced protein ubiquitination occurs. They imply that the synapse is a specialized site where the activation process is not only triggered, but also controlled via ubiquitination of signaling actors.
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Affiliation(s)
- Aurelie Wiedemann
- INSERM U563, Institut Claude de Preval, CHU Purpan, 31059 Toulouse Cedex 3, France
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Carter S, Urbé S, Clague MJ. The met receptor degradation pathway: requirement for Lys48-linked polyubiquitin independent of proteasome activity. J Biol Chem 2004; 279:52835-9. [PMID: 15466866 DOI: 10.1074/jbc.m407769200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Acute stimulation of the receptor for the hepatocyte growth factor/scatter factor Met leads to receptor monoubiquitination and down-regulation through the lysosomal degradation pathway. We have determined that the Met receptor undergoes multiple monoubiquitination as opposed to the appendage of polyubiquitin chains. Nevertheless, overexpression of ubiquitin in HEK293T cells enhances the rate of Met receptor degradation, in contrast to a point mutant of ubiquitin (K48R) that cannot form Lys(48)-linked polyubiquitin chains. Furthermore, an enhancement of Met degradation is also seen under conditions where the proteasome is inhibited by lactacystin. We propose that this reflects polyubiquitin-dependent sorting of Met, as the overexpression of ubiquitin but not K48R ubiquitin also restores hepatocyte growth factor-dependent phosphorylation of the endosomal coat protein Hrs from inhibition by lactacystin. Our data indicate a requirement for K48R-linked polyubiquitin for Met endosomal trafficking independent of its canonical function of targeting for proteasomal degradation.
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Affiliation(s)
- Stephanie Carter
- Physiological Laboratory, University of Liverpool, Crown St. Liverpool L69 3BX, UK
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