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The evolving role of ubiquitin modification in endoplasmic reticulum-associated degradation. Biochem J 2017; 474:445-469. [PMID: 28159894 DOI: 10.1042/bcj20160582] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/12/2016] [Accepted: 12/14/2016] [Indexed: 12/13/2022]
Abstract
The endoplasmic reticulum (ER) serves as a warehouse for factors that augment and control the biogenesis of nascent proteins entering the secretory pathway. In turn, this compartment also harbors the machinery that responds to the presence of misfolded proteins by targeting them for proteolysis via a process known as ER-associated degradation (ERAD). During ERAD, substrates are selected, modified with ubiquitin, removed from the ER, and then degraded by the cytoplasmic 26S proteasome. While integral membrane proteins can directly access the ubiquitination machinery that resides in the cytoplasm or on the cytoplasmic face of the ER membrane, soluble ERAD substrates within the lumen must be retrotranslocated from this compartment. In either case, nearly all ERAD substrates are tagged with a polyubiquitin chain, a modification that represents a commitment step to degrade aberrant proteins. However, increasing evidence indicates that the polyubiquitin chain on ERAD substrates can be further modified, serves to recruit ERAD-requiring factors, and may regulate the ERAD machinery. Amino acid side chains other than lysine on ERAD substrates can also be modified with ubiquitin, and post-translational modifications that affect substrate ubiquitination have been observed. Here, we summarize these data and provide an overview of questions driving this field of research.
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Yang L, Mu Y, Cui H, Liang Y, Su X. MiR-9-3p augments apoptosis induced by H2O2 through down regulation of Herpud1 in glioma. PLoS One 2017; 12:e0174839. [PMID: 28430789 PMCID: PMC5400238 DOI: 10.1371/journal.pone.0174839] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 03/03/2017] [Indexed: 12/25/2022] Open
Abstract
MicroRNAs are short, single-stranded non-coding RNA molecules that function as regulators of tumor progression in various cancers, including glioma. The present study sought to investigate the biological functions of miR-9-3p in glioma progression. The results of a microRNA microarray indicated that microRNA-9-3p (miR-9-3p, miR-9*) is down-regulated in high-grade (grades III and IV) gliomas compared with non-tumor tissues. These results were confirmed with real-time PCR. The miR-9-3p expression level was associated with age and tumor grade. Herpud1 was regulated by miR-9-3p in glioma cells and tissues and was identified as a miR-9-3p target with luciferase reporter assays. Glioma cells transfected with miR-9-3p mimics or HERPUD1-RNAi had more apoptotic cells than them in control after induced by H2O2. Our results indicated that low expression of miR-9-3p results in a high level of Herpud1, which may protect against apoptosis in glioma.
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Affiliation(s)
- Ling Yang
- Clinical Medicine Research Center, the Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia Autonomous Region, China
| | - Yongping Mu
- Department of Clinical Laboratory, the Affiliated People’s Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia Autonomous Region, China
| | - Hongwei Cui
- Clinical Medicine Research Center, the Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia Autonomous Region, China
| | - Yabing Liang
- Clinical Medicine Research Center, the Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia Autonomous Region, China
| | - Xiulan Su
- Clinical Medicine Research Center, the Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia Autonomous Region, China
- * E-mail:
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Steffen J, Vashisht AA, Wan J, Jen JC, Claypool SM, Wohlschlegel JA, Koehler CM. Rapid degradation of mutant SLC25A46 by the ubiquitin-proteasome system results in MFN1/2-mediated hyperfusion of mitochondria. Mol Biol Cell 2017; 28:600-612. [PMID: 28057766 PMCID: PMC5328619 DOI: 10.1091/mbc.e16-07-0545] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 12/12/2016] [Accepted: 12/30/2016] [Indexed: 11/29/2022] Open
Abstract
SCL25A46 is a mitochondrial carrier protein that localizes to the outer membrane. Mutation L341P causes rapid degradation of SLC25A46 by the ubiquitin-proteasome system, independent of activated stress pathways, including mitophagy and apoptosis. SLC25A46 regulates oligomerization of MFN1/2 and mitochondrial dynamics. SCL25A46 is a mitochondrial carrier protein that surprisingly localizes to the outer membrane and is distantly related to Ugo1. Here we show that a subset of SLC25A46 interacts with mitochondrial dynamics components and the MICOS complex. Decreased expression of SLC25A46 results in increased stability and oligomerization of MFN1 and MFN2 on mitochondria, promoting mitochondrial hyperfusion. A mutation at L341P causes rapid degradation of SLC25A46, which manifests as a rare disease, pontocerebellar hypoplasia. The E3 ubiquitin ligases MULAN and MARCH5 coordinate ubiquitylation of SLC25A46 L341P, leading to degradation by organized activities of P97 and the proteasome. Whereas outer mitochondrial membrane–associated degradation is typically associated with apoptosis or a specialized type of autophagy termed mitophagy, SLC25A46 degradation operates independently of activation of outer membrane stress pathways. Thus SLC25A46 is a new component in mitochondrial dynamics that serves as a regulator for MFN1/2 oligomerization. Moreover, SLC25A46 is selectively degraded from the outer membrane independently of mitophagy and apoptosis, providing a framework for mechanistic studies in the proteolysis of outer membrane proteins.
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Affiliation(s)
- Janos Steffen
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095
| | - Ajay A Vashisht
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
| | - Jijun Wan
- Department of Neurology, University of California, Los Angeles, Los Angeles, CA 90095
| | - Joanna C Jen
- Department of Neurology, University of California, Los Angeles, Los Angeles, CA 90095
| | - Steven M Claypool
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - James A Wohlschlegel
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095.,Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095
| | - Carla M Koehler
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095 .,Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095.,Jonsson Comprehensive Cancer Center, University of California, Los Angeles, Los Angeles, CA 90095
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Ding W, Chen R, Wu C, Chen W, Zhang H, Fan X, Wang H, Ji Y, Xie L, Ning X, Shen L. Increased expression of HERPUD1 involves in neuronal apoptosis after intracerebral hemorrhage. Brain Res Bull 2016; 128:40-47. [PMID: 27871950 DOI: 10.1016/j.brainresbull.2016.11.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 11/13/2016] [Accepted: 11/16/2016] [Indexed: 10/20/2022]
Abstract
Homocysteine-inducible endoplasmic reticulum stress-inducible ubiquitin-like domain member 1 protein (HERPUD1) is involved in endoplasmic reticulum stress response. Immense amounts of research showed HERPUD1 plays multiple roles in various models. In this work, we explored the role of HERPUD1 during the pathophysiological processes of intracerebral hemorrhage (ICH). Rat ICH model was established and verified by behavioral test. Western blot and immunohistochemistry revealed a significant up-regulation of HERPUD1 expression around the hematoma after ICH. Besides, the expression of cytochrome c (cyt c) and active caspase-3 increased accompanied to HERPUD1 expression. Double-labeled immunofluorescence indicated HERPUD1 mainly colocalized with neurons. Further study showed HERPUD1 silence brought about up-regulation of apoptosis markers including cyt c and active caspase-3 coupled with increased cell apoptosis in vitro model. All these findings suggested that HERPUD1 might play a protective role in ICH-induced neuronal apoptosis in rat models.
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Affiliation(s)
- Wensen Ding
- Department of Neurology, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu Province, China; Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Medical College of Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Rongrong Chen
- Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Medical College of Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Chunshuai Wu
- Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Medical College of Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Weihai Chen
- Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Medical College of Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Hongtian Zhang
- Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Medical College of Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Xingjuan Fan
- Department of Neurology, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Hongmei Wang
- Department of Neurology, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu Province, China; Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Medical College of Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Yuteng Ji
- Department of Neurology, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu Province, China; Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Medical College of Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Lili Xie
- Department of Neurology, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu Province, China; Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Medical College of Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Xiaojin Ning
- Department of Neurology, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu Province, China; Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Medical College of Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Lihua Shen
- Department of Neurology, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu Province, China.
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Endoplasmic reticulum-resident E3 ubiquitin ligase Hrd1 controls B-cell immunity through degradation of the death receptor CD95/Fas. Proc Natl Acad Sci U S A 2016; 113:10394-9. [PMID: 27573825 DOI: 10.1073/pnas.1606742113] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Humoral immunity involves multiple checkpoints during B-cell development, maturation, and activation. The cell death receptor CD95/Fas-mediated apoptosis plays a critical role in eliminating the unwanted activation of B cells by self-reactive antigens and in maintaining B-cell homeostasis through activation-induced B-cell death (AICD). The molecular mechanisms controlling AICD remain largely undefined. Herein, we show that the E3 ubiquitin ligase Hrd1 protected B cells from activation-induced cell death by degrading the death receptor Fas. Hrd1-null B cells exhibited high Fas expression during activation and rapidly underwent Fas-mediated apoptosis, which could be largely inhibited by FasL neutralization. Fas mutation in Hrd1 KO mice abrogated the increase in B-cell AICD. We identified Hrd1 as the first E3 ubiquitin ligase of the death receptor Fas and Hrd1-mediated Fas destruction as a molecular mechanism in regulating B-cell immunity.
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Abstract
The endoplasmic reticulum is the port of entry for proteins into the secretory pathway and the site of synthesis for several important lipids, including cholesterol, triacylglycerol, and phospholipids. Protein production within the endoplasmic reticulum is tightly regulated by a cohort of resident machinery that coordinates the folding, modification, and deployment of secreted and integral membrane proteins. Proteins failing to attain their native conformation are degraded through the endoplasmic reticulum-associated degradation (ERAD) pathway via a series of tightly coupled steps: substrate recognition, dislocation, and ubiquitin-dependent proteasomal destruction. The same ERAD machinery also controls the flux through various metabolic pathways by coupling the turnover of metabolic enzymes to the levels of key metabolites. We review the current understanding and biological significance of ERAD-mediated regulation of lipid metabolism in mammalian cells.
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Affiliation(s)
- Julian Stevenson
- Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720;
| | - Edmond Y Huang
- Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720;
| | - James A Olzmann
- Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720;
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NAD(P)H quinone oxidoreductase 1 inhibits the proteasomal degradation of homocysteine-induced endoplasmic reticulum protein. Biochem Biophys Res Commun 2016; 473:1276-1280. [DOI: 10.1016/j.bbrc.2016.04.057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 04/12/2016] [Indexed: 01/14/2023]
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58
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Deletion of Herpud1 Enhances Heme Oxygenase-1 Expression in a Mouse Model of Parkinson's Disease. PARKINSONS DISEASE 2016; 2016:6163934. [PMID: 27057372 PMCID: PMC4781986 DOI: 10.1155/2016/6163934] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2015] [Revised: 01/25/2016] [Accepted: 01/28/2016] [Indexed: 01/05/2023]
Abstract
Herp is an endoplasmic reticulum- (ER-) resident membrane protein that plays a role in ER-associated degradation. We studied the expression of Herp and its effect on neurodegeneration in a mouse model of Parkinson's disease (PD), in which both the oxidative stress and the ER stress are evoked. Eight hours after administering a PD-related neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), to mice, the expression of Herp increased at both the mRNA and the protein levels. Experiments using Herpud1 (+/+) and Herpud1 (-/-) mice revealed that the status of acute degeneration of nigrostriatal neurons and reactive astrogliosis was comparable between two genotypes after MPTP injection. However, the expression of a potent antioxidant, heme oxygenase-1 (HO-1), was detected to a higher degree in the astrocytes of Herpud1 (-/-) mice than in the astrocytes of Herpud1 (+/+) mice 24 h after MPTP administration. Further experiments using cultured astrocytes revealed that the stress response against MPP(+), an active form of MPTP, and hydrogen peroxide, both of which cause oxidative stress, was comparable between the two genotypes. These results suggest that deletion of Herpud1 may cause a slightly higher level of initial damage in the nigrastrial neurons after MPTP administration but is compensated for by higher induction of antioxidants such as HO-1 in astrocytes.
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Suzuki Y, Schmitt MJ. Redox diversity in ERAD-mediated protein retrotranslocation from the endoplasmic reticulum: a complex puzzle. Biol Chem 2016; 396:539-54. [PMID: 25741737 DOI: 10.1515/hsz-2014-0299] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 02/23/2015] [Indexed: 11/15/2022]
Abstract
Misfolded and incorrectly assembled proteins in the secretory pathway are eliminated by ubiquitylation and proteasomal degradation in a process known as ER-associated degradation (ERAD). Retrotranslocation of diverse substrates including misfolded proteins and viruses occurs through channels in the ER membrane, which are also utilized for host cell penetration by A/B class protein toxins such as cholera toxin, ricin or K28. According to the current view, disulfide-bonded proteins must either be reduced or rearranged to ensure translocation competence and entry into the cytosol from the ER. As the underlying mechanisms are still largely mysterious, we here focus on the redox status and disulfide isomerization of ERAD substrates and the role of oxidoreductases in the essential process of ER-to-cytosol retrotranslocation.
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Chen F, Wang N, Yang D, Wen X, Mahmoud TN, Zhou D, Tang K, Lin P, Wang A, Jin Y. Herp depletion arrests the S phase of the cell cycle and increases estradiol synthesis in mouse granulosa cells. J Reprod Dev 2016; 62:159-66. [PMID: 26781490 PMCID: PMC4848573 DOI: 10.1262/jrd.2015-120] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The endoplasmic reticulum (ER) stress response has been implicated in the development, atresia and luteinization of ovarian follicles. However, there have been few reports concerning the role of Herp, an ER stress-induced protein, in follicular development. The present study aims to detect the distribution and cyclic variations of Herp during the estrous cycle and to reveal the roles of Herp in regulating the cell cycle, apoptosis and steroid hormone biosynthesis in mouse granulosa cells. In this study, immunohistochemistry staining showed that Herp expression was primarily in the granulosa cells and oocytes. Furthermore, we constructed recombinant lentiviral vectors for Herp short hairpin interfering RNA (shRNA) expression; immunofluorescence staining, real-time quantitative PCR (RT-qPCR) and western blot analysis revealed that Herp was successfully knocked down. Flow cytometry showed that knockdown of Herp arrested granulosa cells at the S phase of the cell cycle. More importantly, ELISA analysis revealed that Herp knockdown significantly upregulated the concentration of estradiol (E2) in the culture supernatants. RT-qPCR was performed to determine the regulatory mechanism of Herp knockdown in the cell cycle, and in steroid synthesis, RT-qPCR analysis revealed that Herp knockdown upregulated the mRNA expression of steroidogenic enzymes (Cyp19a1) and downregulated metabolic enzymes (Cyp1b1) and cell cycle factors (cyclin A1, cyclin B1 and cyclin D2). These results suggest that Herp may regulate the cell cycle and hormone secretions in mouse granulosa cells. The present study helps to elucidate the physiological functions of Herp as they relate to reproduction.
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Affiliation(s)
- Fenglei Chen
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Shaanxi 712100, China
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Paredes F, Parra V, Torrealba N, Navarro-Marquez M, Gatica D, Bravo-Sagua R, Troncoso R, Pennanen C, Quiroga C, Chiong M, Caesar C, Taylor WR, Molgó J, San Martin A, Jaimovich E, Lavandero S. HERPUD1 protects against oxidative stress-induced apoptosis through downregulation of the inositol 1,4,5-trisphosphate receptor. Free Radic Biol Med 2016; 90:206-18. [PMID: 26616647 PMCID: PMC4710961 DOI: 10.1016/j.freeradbiomed.2015.11.024] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Revised: 11/17/2015] [Accepted: 11/20/2015] [Indexed: 11/27/2022]
Abstract
Homocysteine-inducible, endoplasmic reticulum (ER) stress-inducible, ubiquitin-like domain member 1 (HERPUD1), an ER resident protein, is upregulated in response to ER stress and Ca(2+) homeostasis deregulation. HERPUD1 exerts cytoprotective effects in various models, but its role during oxidative insult remains unknown. The aim of this study was to investigate whether HERPUD1 contributes to cytoprotection in response to redox stress and participates in mediating stress-dependent signaling pathways. Our data showed that HERPUD1 protein levels increased in HeLa cells treated for 30 min with H2O2 or angiotensin II and in aortic tissue isolated from mice treated with angiotensin II for 3 weeks. Cell death was higher in HERPUD1 knockdown (sh-HERPUD1) HeLa cells treated with H2O2 in comparison with control (sh-Luc) HeLa cells. This effect was abolished by the intracellular Ca(2+) chelating agent BAPTA-AM or the inositol 1,4,5-trisphosphate receptor (ITPR) antagonist xestospongin B, suggesting that the response to H2O2 was dependent on intracellular Ca(2+) stores and the ITPR. Ca(2+) kinetics showed that sh-HERPUD1 HeLa cells exhibited greater and more sustained cytosolic and mitochondrial Ca(2+) increases than sh-Luc HeLa cells. This higher sensitivity of sh-HERPUD1 HeLa cells to H2O2 was prevented with the mitochondrial permeability transition pore inhibitor cyclosporine A. We concluded that the HERPUD1-mediated cytoprotective effect against oxidative stress depends on the ITPR and Ca(2+) transfer from the ER to mitochondria.
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Affiliation(s)
- Felipe Paredes
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, 838049 Santiago, Chile
| | - Valentina Parra
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, 838049 Santiago, Chile
| | - Natalia Torrealba
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, 838049 Santiago, Chile
| | - Mario Navarro-Marquez
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, 838049 Santiago, Chile
| | - Damian Gatica
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, 838049 Santiago, Chile
| | - Roberto Bravo-Sagua
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, 838049 Santiago, Chile
| | - Rodrigo Troncoso
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, 838049 Santiago, Chile; Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile
| | - Christian Pennanen
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, 838049 Santiago, Chile
| | - Clara Quiroga
- ACCDiS, Cardiovascular Diseases Division, Faculty of Medicine, Pontifical Catholic University of Chile, Santiago, Chile
| | - Mario Chiong
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, 838049 Santiago, Chile
| | - Christa Caesar
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, GA, USA
| | - W Robert Taylor
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, GA, USA; Department of Medicine, Division of Cardiology, Emory University School of Medicine, Atlanta, GA, USA
| | - Jordi Molgó
- Institut des Neurosciences Paris-Saclay, UMR 9197, 91190 Gif sur Yvette, France
| | - Alejandra San Martin
- Department of Medicine, Division of Cardiology, Emory University School of Medicine, Atlanta, GA, USA
| | - Enrique Jaimovich
- Centro de Estudios Moleculares de la Célula, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Sergio Lavandero
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, 838049 Santiago, Chile; Centro de Estudios Moleculares de la Célula, Facultad de Medicina, Universidad de Chile, Santiago, Chile; Department of Internal Medicine (Cardiology Division), University of Texas Southwestern Medical Center, Dallas, TX, USA.
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Chen F, Lin P, Wang N, Yang D, Wen X, Zhou D, Wang A, Jin Y. Herp depletion inhibits zearalenone-induced cell death in RAW 264.7 macrophages. Toxicol In Vitro 2015; 32:115-22. [PMID: 26723276 DOI: 10.1016/j.tiv.2015.12.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Revised: 11/26/2015] [Accepted: 12/18/2015] [Indexed: 12/14/2022]
Abstract
Herp is an endoplasmic reticulum (ER) membrane protein and strongly induced by the ER stress that not only participates in the unfolded protein response (UPR) under the ER stress, but also in cell autophagy under glucose starvation (GS). However, we do not know whether Herp plays any roles in other responses, such as zearalenone (ZEA). In this study, we constructed recombinant lentiviral vectors for Herp shRNA expression and generated stable Herp knockdown RAW 264.7 macrophages. Flow cytometry analysis showed Herp depletion could inhibit cell death induced by ZEA. Western blot analysis revealed that Herp depletion could up-regulate autophagy-related protein LC3-I conversion into LC3-II and the expression of ER stress-related protein CHOP. These results suggest that Herp depletion inhibits cell death by up-regulating autophagy.
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Affiliation(s)
- Fenglei Chen
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi 712100, China; College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Pengfei Lin
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi 712100, China; College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Nan Wang
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi 712100, China; College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Diqi Yang
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi 712100, China; College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Xin Wen
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi 712100, China; College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Dong Zhou
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi 712100, China; College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Aihua Wang
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Yaping Jin
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi 712100, China; College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi 712100, China.
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63
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Sun S, Shi G, Sha H, Ji Y, Han X, Shu X, Ma H, Inoue T, Gao B, Kim H, Bu P, Guber RD, Shen X, Lee AH, Iwawaki T, Paton AW, Paton JC, Fang D, Tsai B, Yates JR, Wu H, Kersten S, Long Q, Duhamel GE, Simpson KW, Qi L. IRE1α is an endogenous substrate of endoplasmic-reticulum-associated degradation. Nat Cell Biol 2015; 17:1546-55. [PMID: 26551274 PMCID: PMC4670240 DOI: 10.1038/ncb3266] [Citation(s) in RCA: 173] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 10/05/2015] [Indexed: 12/13/2022]
Abstract
Endoplasmic reticulum (ER)-associated degradation (ERAD) represents a principle quality control mechanism to clear misfolded proteins in the ER; however its physiological significance and the nature of endogenous ERAD substrates remain largely unexplored. Here we discover that IRE1α, the sensor of unfolded protein response (UPR), is a bona fide substrate of the Sel1L-Hrd1 ERAD complex. ERAD-mediated IRE1α degradation occurs under basal conditions in a BiP-dependent manner, requires both intramembrane hydrophilic residues of IRE1α and lectin protein OS9, and is attenuated by ER stress. ERAD deficiency causes IRE1α protein stabilization, accumulation and mild activation both in vitro and in vivo. Although enterocyte-specific Sel1L-knockout mice (Sel1LΔIEC) are viable and appear normal, they are highly susceptible to experimental colitis and inflammation-associated dysbiosis, in an IRE1α-dependent but CHOP-independent manner. Hence, Sel1L-Hrd1 ERAD serves a distinct, essential function in restraint of IRE1α signaling in vivo by managing its protein turnover.
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Affiliation(s)
- Shengyi Sun
- Graduate Program in Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853, USA
| | - Guojun Shi
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853, USA
| | - Haibo Sha
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853, USA
| | - Yewei Ji
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853, USA
| | - Xuemei Han
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Xin Shu
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853, USA
| | - Hongming Ma
- Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas 79905, USA
| | - Takamasa Inoue
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - Beixue Gao
- Department of Pathology, Northwestern University, Chicago, Illinois 60611, USA
| | - Hana Kim
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853, USA
| | - Pengcheng Bu
- Department of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853, USA.,Department of Biomedical Engineering, Cornell University, Ithaca, New York 14853, USA
| | - Robert D Guber
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853, USA
| | - Xiling Shen
- Department of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853, USA.,Department of Biomedical Engineering, Cornell University, Ithaca, New York 14853, USA.,Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA
| | - Ann-Hwee Lee
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, New York 10021, USA
| | - Takao Iwawaki
- Education and Research Support Center, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan
| | - Adrienne W Paton
- Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - James C Paton
- Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Deyu Fang
- Department of Pathology, Northwestern University, Chicago, Illinois 60611, USA
| | - Billy Tsai
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - John R Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Haoquan Wu
- Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas 79905, USA
| | - Sander Kersten
- Nutrition Metabolism and Genomics group, Wageningen University, Bomenweg 2, 6703HD Wageningen, The Netherlands
| | - Qiaoming Long
- Laboratory Animal Research Center, Medical College of Soochow University, Suzhou 215006, Jiangsu, China
| | - Gerald E Duhamel
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA
| | - Kenneth W Simpson
- Department of Clinical Science, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA
| | - Ling Qi
- Graduate Program in Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853, USA.,Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853, USA
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Hosokawa N, Wada I. Association of the SEL1L protein transmembrane domain with HRD1 ubiquitin ligase regulates ERAD-L. FEBS J 2015; 283:157-72. [PMID: 26471130 DOI: 10.1111/febs.13564] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Revised: 09/25/2015] [Accepted: 10/13/2015] [Indexed: 11/28/2022]
Abstract
Misfolded proteins in the endoplasmic reticulum (ER) are transported to the cytoplasm for degradation by the ubiquitin-proteasome system, a process otherwise known as ER-associated degradation (ERAD). Mammalian HRD1, an integral membrane ubiquitin ligase that ubiquitinates ERAD substrates, forms a large assembly in the ER membrane including SEL1L, a single-pass membrane protein, and additional components. The mechanism by which these molecules export misfolded proteins through the ER membrane remains unclear. Unlike Hrd3p, the homologue in Saccharomyces cerevisiae, human SEL1L is an unstable protein, which is restored by the association with HRD1. Here we report that the inherently unstable nature of the human SEL1L protein lies in its transmembrane domain, and that association of HRD1 with the SEL1L transmembrane domain restored its stability. On the other hand, we found that the SEL1L luminal domain escaped degradation, and inhibited the degradation of misfolded α1 -antitrypsin variant null Hong Kong by retaining the misfolded cargo in the ER. Overexpression of HRD1 inhibited the degradation of unfolded secretory cargo, which was restored by the interaction of HRD1 with the SEL1L transmembrane domain. Hence, we propose that SEL1L critically regulates HRD1-mediated disposal of misfolded cargo through its short membrane spanning stretch.
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Affiliation(s)
- Nobuko Hosokawa
- Department of Molecular and Cellular Biology, Institute for Frontier Medical Sciences, Kyoto University, Japan
| | - Ikuo Wada
- Department of Cell Sciences, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine, Japan
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65
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Sasset L, Petris G, Cesaratto F, Burrone OR. The VCP/p97 and YOD1 Proteins Have Different Substrate-dependent Activities in Endoplasmic Reticulum-associated Degradation (ERAD). J Biol Chem 2015; 290:28175-28188. [PMID: 26463207 DOI: 10.1074/jbc.m115.656660] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Indexed: 11/06/2022] Open
Abstract
Endoplasmic reticulum-associated degradation (ERAD) is an essential quality control mechanism of the folding state of proteins in the secretory pathway that targets unfolded/misfolded polypeptides for proteasomal degradation. The cytosolic p97/valosin-containing protein is an essential ATPase for degradation of ERAD substrates. It has been considered necessary during retro-translocation to extract proteins from the endoplasmic reticulum that are otherwise supposed to accumulate in the endoplasmic reticulum lumen. The activity of the p97-associated deubiquitinylase YOD1 is also required for substrate disposal. We used the in vivo biotinylation retro-translocation assay in mammalian cells under conditions of impaired p97 or YOD1 activity to directly discriminate their requirements and diverse functions in ERAD. Using different ERAD substrates, we found that both proteins participate in two distinct retro-translocation steps. For CD4 and MHC-Iα, which are induced to degradation by the HIV-1 protein Vpu and by the CMV immunoevasins US2 and US11, respectively, p97 and YOD1 have a retro-translocation-triggering role. In contrast, for three other spontaneous ERAD model substrates (NS1, NHK-α1AT, and BST-2/Tetherin), p97 and YOD1 are required in the downstream events of substrate deglycosylation and proteasomal degradation.
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Affiliation(s)
- Linda Sasset
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy
| | - Gianluca Petris
- CIBIO, University of Trento, Via delle Regole 101, 38123 Mattarello, Italy.
| | - Francesca Cesaratto
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy
| | - Oscar R Burrone
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy
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66
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Benyair R, Ogen-Shtern N, Lederkremer GZ. Glycan regulation of ER-associated degradation through compartmentalization. Semin Cell Dev Biol 2015; 41:99-109. [DOI: 10.1016/j.semcdb.2014.11.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 11/13/2014] [Accepted: 11/14/2014] [Indexed: 12/20/2022]
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67
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Ho DV, Chan JY. Induction of Herpud1 expression by ER stress is regulated by Nrf1. FEBS Lett 2015; 589:615-20. [PMID: 25637874 PMCID: PMC10084809 DOI: 10.1016/j.febslet.2015.01.026] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 01/16/2015] [Accepted: 01/20/2015] [Indexed: 12/30/2022]
Abstract
Herpud1 is an ER-localized protein that contributes to endoplasmic reticulum (ER) homeostasis by participating in the ER-associated protein degradation pathway. The Nrf1 transcription factor is important in cellular stress pathways. We show that loss of Nrf1 function results in decreased Herpud1 expression in cells and liver tissues. Expression of Herpud1 increases in response to ER stress, but not in Nrf1 knockout cells. Transactivation studies show that Nrf1 acts through antioxidant response elements located in the Herpud1 promoter, and chromatin immunoprecipitation demonstrates that Herpud1 is a direct Nrf1 target gene. These results indicate that Nrf1 is a transcriptional activator of Herpud1 expression during ER stress, and they suggest Nrf1 is a key player in the regulation of the ER stress response in cells.
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Affiliation(s)
- Daniel V Ho
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Sciences, Irvine, CA 92697, USA
| | - Jefferson Y Chan
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Sciences, Irvine, CA 92697, USA.
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68
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Abstract
AbstractRecent research has identified ER stress as a major mechanism implicated in cytotoxicity in many neurodegenerative diseases, among them Huntington’s disease. This genetic disorder is of late-onset, progressive and fatal, affecting cognition and movement. There is presently no cure nor any effective therapy for the disease. This review focuses on recent findings that shed light on the mechanisms of the advent and development of ER stress in Huntington’s disease and on its implications, highlighting possible therapeutic avenues that are being or could be explored.
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69
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Ichhaporia VP, Sanford T, Howes J, Marion TN, Hendershot LM. Sil1, a nucleotide exchange factor for BiP, is not required for antibody assembly or secretion. Mol Biol Cell 2014; 26:420-9. [PMID: 25473114 PMCID: PMC4310734 DOI: 10.1091/mbc.e14-09-1392] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Sil1 is a nucleotide exchange factor for the ER chaperone BiP, and mutations in this gene lead to Marinesco–Sjögren syndrome, a multisystem disorder. Effects of loss of Sil1 on biosynthesis and secretion of antibodies, a well-characterized BiP client, are determined in a mouse model for this disease and patient-derived lymphoblastoid cell lines. Sil1 is a nucleotide exchange factor for the endoplasmic reticulum chaperone BiP, and mutations in this gene lead to Marinesco–Sjögren syndrome (MSS), a debilitating autosomal recessive disease characterized by multisystem defects. A mouse model for MSS was previously produced by disrupting Sil1 using gene-trap methodology. The resulting Sil1Gt mouse phenocopies several pathologies associated with MSS, although its ability to assemble and secrete antibodies, the best-characterized substrate of BiP, has not been investigated. In vivo antigen-specific immunizations and ex vivo LPS stimulation of splenic B cells revealed that the Sil1Gt mouse was indistinguishable from wild-type age-matched controls in terms of both the kinetics and magnitude of antigen-specific antibody responses. There was no significant accumulation of BiP-associated Ig assembly intermediates or evidence that another molecular chaperone system was used for antibody production in the LPS-stimulated splenic B cells from Sil1Gt mice. ER chaperones were expressed at the same level in Sil1WT and Sil1Gt mice, indicating that there was no evident compensation for the disruption of Sil1. Finally, these results were confirmed and extended in three human EBV-transformed lymphoblastoid cell lines from individuals with MSS, leading us to conclude that the BiP cofactor Sil1 is dispensable for antibody production.
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Affiliation(s)
- Viraj P Ichhaporia
- Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, TN 38105; Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Sciences Center, Memphis, TN 38163
| | - Tyler Sanford
- Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, TN 38105; Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Sciences Center, Memphis, TN 38163
| | - Jenny Howes
- Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, TN 38105
| | - Tony N Marion
- Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Sciences Center, Memphis, TN 38163
| | - Linda M Hendershot
- Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, TN 38105;
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70
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Improving the Secretory Production of the Heterologous Protein in Pichia pastoris by Focusing on Protein Folding. Appl Biochem Biotechnol 2014; 175:535-48. [DOI: 10.1007/s12010-014-1292-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2014] [Accepted: 10/09/2014] [Indexed: 01/07/2023]
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71
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Piterman R, Braunstein I, Isakov E, Ziv T, Navon A, Cohen S, Stanhill A. VWA domain of S5a restricts the ability to bind ubiquitin and Ubl to the 26S proteasome. Mol Biol Cell 2014; 25:3988-98. [PMID: 25318673 PMCID: PMC4263443 DOI: 10.1091/mbc.e13-11-0697] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The only stoichiometric proteasomal subunit found to reside outside the proteasome is the ubiquitin receptor S5a. S5a-dependent binding of substrates and shuttle factors is restricted to occur only on the proteasome, thus increasing efficiency of substrate degradation by the 26S proteasome. The 26S proteasome recognizes a vast number of ubiquitin-dependent degradation signals linked to various substrates. This recognition is mediated mainly by the stoichiometric proteasomal resident ubiquitin receptors S5a and Rpn13, which harbor ubiquitin-binding domains. Regulatory steps in substrate binding, processing, and subsequent downstream proteolytic events by these receptors are poorly understood. Here we demonstrate that mammalian S5a is present in proteasome-bound and free states. S5a is required for efficient proteasomal degradation of polyubiquitinated substrates and the recruitment of ubiquitin-like (Ubl) harboring proteins; however, S5a-mediated ubiquitin and Ubl binding occurs only on the proteasome itself. We identify the VWA domain of S5a as a domain that limits ubiquitin and Ubl binding to occur only upon proteasomal association. Multiubiquitination events within the VWA domain can further regulate S5a association. Our results provide a molecular explanation to how ubiquitin and Ubl binding to S5a is restricted to the 26S proteasome.
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Affiliation(s)
- Ravit Piterman
- Department of Biochemistry, Rappaport Family Institute for Research in the Medical Sciences, Technion-Israel Institute of Technology, Haifa 31096, Israel
| | - Ilana Braunstein
- Department of Biochemistry, Rappaport Family Institute for Research in the Medical Sciences, Technion-Israel Institute of Technology, Haifa 31096, Israel
| | - Elada Isakov
- Department of Biochemistry, Rappaport Family Institute for Research in the Medical Sciences, Technion-Israel Institute of Technology, Haifa 31096, Israel
| | - Tamar Ziv
- Smoler Proteomics Center, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Ami Navon
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Shenhav Cohen
- Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Ariel Stanhill
- Department of Biochemistry, Rappaport Family Institute for Research in the Medical Sciences, Technion-Israel Institute of Technology, Haifa 31096, Israel
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72
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Chambers JE, Marciniak SJ. Cellular mechanisms of endoplasmic reticulum stress signaling in health and disease. 2. Protein misfolding and ER stress. Am J Physiol Cell Physiol 2014; 307:C657-70. [PMID: 24944205 DOI: 10.1152/ajpcell.00183.2014] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The endoplasmic reticulum (ER) is a major site of protein synthesis, most strikingly in the specialized secretory cells of metazoans, which can produce their own weight in proteins daily. Cells possess a diverse machinery to ensure correct folding, assembly, and secretion of proteins from the ER. When this machinery is overwhelmed, the cell is said to experience ER stress, a result of the accumulation of unfolded or misfolded proteins in the lumen of the organelle. Here we discuss the causes of ER stress and the mechanisms by which cells elicit a response, with an emphasis on recent discoveries.
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Affiliation(s)
- Joseph E Chambers
- Department of Medicine, University of Cambridge, Cambridge Institute for Medical Research, Cambridge, United Kingdom
| | - Stefan J Marciniak
- Department of Medicine, University of Cambridge, Cambridge Institute for Medical Research, Cambridge, United Kingdom
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73
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Zattas D, Hochstrasser M. Ubiquitin-dependent protein degradation at the yeast endoplasmic reticulum and nuclear envelope. Crit Rev Biochem Mol Biol 2014; 50:1-17. [PMID: 25231236 DOI: 10.3109/10409238.2014.959889] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The endoplasmic reticulum (ER) is the primary organelle in eukaryotic cells where membrane and secreted proteins are inserted into or across cell membranes. Its membrane bilayer and luminal compartments provide a favorable environment for the folding and assembly of thousands of newly synthesized proteins. However, protein folding is intrinsically error-prone, and various stress conditions can further increase levels of protein misfolding and damage, particularly in the ER, which can lead to cellular dysfunction and disease. The ubiquitin-proteasome system (UPS) is responsible for the selective destruction of a vast array of protein substrates, either for protein quality control or to allow rapid changes in the levels of specific regulatory proteins. In this review, we will focus on the components and mechanisms of ER-associated protein degradation (ERAD), an important branch of the UPS. ER membranes extend from subcortical regions of the cell to the nuclear envelope, with its continuous outer and inner membranes; the nuclear envelope is a specialized subdomain of the ER. ERAD presents additional challenges to the UPS beyond those faced with soluble substrates of the cytoplasm and nucleus. These include recognition of sugar modifications that occur in the ER, retrotranslocation of proteins across the membrane bilayer, and transfer of substrates from the ER extraction machinery to the proteasome. Here, we review characteristics of ERAD substrate degradation signals (degrons), mechanisms underlying substrate recognition and processing by the ERAD machinery, and ideas on the still unresolved problem of how substrate proteins are moved across and extracted from the ER membrane.
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Affiliation(s)
- Dimitrios Zattas
- Department of Molecular Biophysics & Biochemistry, Yale University , New Haven, CT , USA
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74
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Zhang Z, Shrestha J, Tateda C, Greenberg JT. Salicylic acid signaling controls the maturation and localization of the arabidopsis defense protein ACCELERATED CELL DEATH6. MOLECULAR PLANT 2014; 7:1365-1383. [PMID: 24923602 PMCID: PMC4168298 DOI: 10.1093/mp/ssu072] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
ACCELERATED CELL DEATH6 (ACD6) is a multipass membrane protein with an ankyrin domain that acts in a positive feedback loop with the defense signal salicylic acid (SA). This study implemented biochemical approaches to infer changes in ACD6 complexes and localization. In addition to forming endoplasmic reticulum (ER)- and plasma membrane (PM)-localized complexes, ACD6 forms soluble complexes, where it is bound to cytosolic HSP70, ubiquitinated, and degraded via the proteasome. Thus, ACD6 constitutively undergoes ER-associated degradation. During SA signaling, the soluble ACD6 pool decreases, whereas the PM pool increases. Similarly, ACD6-1, an activated version of ACD6 that induces SA, is present at low levels in the soluble fraction and high levels in the PM. However, ACD6 variants with amino acid substitutions in the ankyrin domain form aberrant, inactive complexes, are induced by a SA agonist, but show no PM localization. SA signaling also increases the PM pools of FLAGELLIN SENSING2 (FLS2) and BRI1-ASSOCIATED RECEPTOR KINASE 1 (BAK1). FLS2 forms complexes ACD6; both FLS2 and BAK1 require ACD6 for maximal accumulation at the PM in response to SA signaling. A plausible scenario is that SA increases the efficiency of productive folding and/or complex formation in the ER, such that ACD6, together with FLS2 and BAK1, reaches the cell surface to more effectively promote immune responses.
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Affiliation(s)
- Zhongqin Zhang
- Department of Molecular Genetics and Cell Biology, University of Chicago, 929 East 57 Street, GCIS W524, Chicago, IL 60637, USA
| | - Jay Shrestha
- Department of Molecular Genetics and Cell Biology, University of Chicago, 929 East 57 Street, GCIS W524, Chicago, IL 60637, USA
| | - Chika Tateda
- Department of Molecular Genetics and Cell Biology, University of Chicago, 929 East 57 Street, GCIS W524, Chicago, IL 60637, USA
| | - Jean T Greenberg
- Department of Molecular Genetics and Cell Biology, University of Chicago, 929 East 57 Street, GCIS W524, Chicago, IL 60637, USA.
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75
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Byun H, Gou Y, Zook A, Lozano MM, Dudley JP. ERAD and how viruses exploit it. Front Microbiol 2014; 5:330. [PMID: 25071743 PMCID: PMC4080680 DOI: 10.3389/fmicb.2014.00330] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 06/16/2014] [Indexed: 01/09/2023] Open
Abstract
Endoplasmic reticulum (ER)-associated degradation (ERAD) is a universally important process among eukaryotic cells. ERAD is necessary to preserve cell integrity since the accumulation of defective proteins results in diseases associated with neurological dysfunction, cancer, and infections. This process involves recognition of misfolded or misassembled proteins that have been translated in association with ER membranes. Recognition of ERAD substrates leads to their extraction through the ER membrane (retrotranslocation or dislocation), ubiquitination, and destruction by cytosolic proteasomes. This review focuses on ERAD and its components as well as how viruses use this process to promote their replication and to avoid the immune response.
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Affiliation(s)
- Hyewon Byun
- Department of Molecular Biosciences, Center for Infectious Diseases and Institute for Cellular and Molecular Biology, The University of Texas at Austin Austin, TX, USA
| | - Yongqiang Gou
- Department of Molecular Biosciences, Center for Infectious Diseases and Institute for Cellular and Molecular Biology, The University of Texas at Austin Austin, TX, USA
| | - Adam Zook
- Department of Molecular Biosciences, Center for Infectious Diseases and Institute for Cellular and Molecular Biology, The University of Texas at Austin Austin, TX, USA
| | - Mary M Lozano
- Department of Molecular Biosciences, Center for Infectious Diseases and Institute for Cellular and Molecular Biology, The University of Texas at Austin Austin, TX, USA
| | - Jaquelin P Dudley
- Department of Molecular Biosciences, Center for Infectious Diseases and Institute for Cellular and Molecular Biology, The University of Texas at Austin Austin, TX, USA
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76
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Christianson JC, Ye Y. Cleaning up in the endoplasmic reticulum: ubiquitin in charge. Nat Struct Mol Biol 2014; 21:325-35. [PMID: 24699081 DOI: 10.1038/nsmb.2793] [Citation(s) in RCA: 290] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2013] [Accepted: 02/10/2014] [Indexed: 12/18/2022]
Abstract
The eukaryotic endoplasmic reticulum (ER) maintains protein homeostasis by eliminating unwanted proteins through the evolutionarily conserved ER-associated degradation (ERAD) pathway. During ERAD, maturation-defective and surplus polypeptides are evicted from the ER lumen and/or lipid bilayer through the process of retrotranslocation and ultimately degraded by the proteasome. An integral facet of the ERAD mechanism is the ubiquitin system, composed of the ubiquitin modifier and the factors for assembling, processing and binding ubiquitin chains on conjugated substrates. Beyond simply marking polypeptides for degradation, the ubiquitin system is functionally intertwined with retrotranslocation machinery to transport polypeptides across the ER membrane.
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Affiliation(s)
- John C Christianson
- 1] Ludwig Institute for Cancer Research, University of Oxford, Oxford, UK. [2]
| | - Yihong Ye
- 1] Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA. [2]
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77
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Dersh D, Jones SM, Eletto D, Christianson JC, Argon Y. OS-9 facilitates turnover of nonnative GRP94 marked by hyperglycosylation. Mol Biol Cell 2014; 25:2220-34. [PMID: 24899641 PMCID: PMC4116297 DOI: 10.1091/mbc.e14-03-0805] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
ER quality control factors GRP94 and OS-9 associate not for the disposal of ERAD substrates but
instead because OS-9 sequesters and degrades aberrant forms of GRP94, which are hyperglycosylated at
cryptic acceptor sites and have altered structure and activity. This highlights a novel mechanism of
quality control of an ER-resident chaperone. The tight coupling of protein folding pathways with disposal mechanisms promotes the efficacy of
protein production in the endoplasmic reticulum (ER). It has been hypothesized that the ER-resident
molecular chaperone glucose-regulated protein 94 (GRP94) is part of this quality control coupling
because it supports folding of select client proteins yet also robustly associates with the lectin
osteosarcoma amplified 9 (OS-9), a component involved in ER-associated degradation (ERAD). To
explore this possibility, we investigated potential functions for the GRP94/OS-9 complex in ER
quality control. Unexpectedly, GRP94 does not collaborate with OS-9 in ERAD of misfolded substrates,
nor is the chaperone required directly for OS-9 folding. Instead, OS-9 binds preferentially to a
subpopulation of GRP94 that is hyperglycosylated on cryptic N-linked glycan acceptor sites.
Hyperglycosylated GRP94 forms have nonnative conformations and are less active. As a result, these
species are degraded much faster than the major, monoglycosylated form of GRP94 in an
OS-9–mediated, ERAD-independent, lysosomal-like mechanism. This study therefore clarifies
the role of the GRP94/OS-9 complex and describes a novel pathway by which glycosylation of cryptic
acceptor sites influences the function and fate of an ER-resident chaperone.
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Affiliation(s)
- Devin Dersh
- Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Stephanie M Jones
- Ludwig Institute for Cancer Research, University of Oxford, Oxford OX3 7DQ, United Kingdom
| | - Davide Eletto
- Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104
| | - John C Christianson
- Ludwig Institute for Cancer Research, University of Oxford, Oxford OX3 7DQ, United Kingdom
| | - Yair Argon
- Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
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78
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Nakatsukasa K, Kamura T, Brodsky JL. Recent technical developments in the study of ER-associated degradation. Curr Opin Cell Biol 2014; 29:82-91. [PMID: 24867671 DOI: 10.1016/j.ceb.2014.04.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 04/04/2014] [Accepted: 04/23/2014] [Indexed: 11/25/2022]
Abstract
Endoplasmic reticulum-associated degradation (ERAD) is a mechanism during which native and misfolded proteins are recognized and retrotranslocated across the ER membrane to the cytosol for degradation by the ubiquitin-proteasome system. Like other cellular pathways, the factors required for ERAD have been analyzed using both conventional genetic and biochemical approaches. More recently, however, an integrated top-down approach has identified a functional network that underlies the ERAD system. In turn, bottom-up reconstitution has become increasingly sophisticated and elucidated the molecular mechanisms underlying substrate recognition, ubiquitylation, retrotranslocation, and degradation. In addition, a live cell imaging technique and a site-specific in vivo photo-crosslinking approach have further dissected specific steps during ERAD. These technical developments have revealed an unexpected dynamicity of the membrane-associated ERAD complex. In this article, we will discuss how these technical developments have improved our understanding of the ERAD pathway and have led to new questions.
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Affiliation(s)
- Kunio Nakatsukasa
- Division of Biological Sciences, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan.
| | - Takumi Kamura
- Division of Biological Sciences, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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79
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Zhang T, Ye Y. The final moments of misfolded proteins en route to the proteasome. DNA Cell Biol 2014; 33:477-83. [PMID: 24833120 DOI: 10.1089/dna.2014.2452] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Protein homeostasis in the endoplasmic reticulum (ER) in eukaryotic cells is maintained by a conserved quality control system named ER-associated degradation (ERAD). The ERAD system retains misfolded or unassembled polypeptides in the ER, retrotranslocates them into the cytosol for degradation by the ubiquitin proteasome system. Central to the ERAD process is the AAA+ (ATPase associated with various cellular activities), ATPase p97/VCP (also known as Cdc48p in yeast), and the proteasome. p97/VCP couples ATP hydrolysis to the extraction of misfolded proteins from retrotranslocation sites and subsequently targets them for degradation, but how p97/VCP hands substrate off to the proteasome is unclear. Recent studies suggest that p97/VCP may either directly translocate polypeptides into the proteolytic compartment of the 20S subcomplex, or use a set of shuttling factors to deliver retrotranslocated polypeptides to the proteasome.
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Affiliation(s)
- Ting Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland
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80
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Inhibition of post-translational N-glycosylation by HRD1 that controls the fate of ABCG5/8 transporter. Sci Rep 2014; 4:4258. [PMID: 24584735 PMCID: PMC3939451 DOI: 10.1038/srep04258] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 02/13/2014] [Indexed: 12/12/2022] Open
Abstract
N-glycosylation of proteins in endoplasmic reticulum is critical for protein quality control. We showed here a post-translational N-glycosylation affected by the HRD1 E3 ubiquitin ligase. Both WT- and E3-defective C329S-HRD1 decreased the level of high mannose form of ABCG8, a protein that heterodimerizes with ABCG5 to control sterol balance. Meanwhile, HRD1 increased the non-glycosylated ABCG8 regardless of its E3 activity, thereby suppressing full maturation of ABCG5/8 transporter. Pulse chase and mutational analysis indicated that HRD1 inhibits STT3B-dependent post-translational N-glycosylation of ABCG8. Whereas, HRD1 had only slight effect on the N-glycosylation status of ABCG5; rather it accelerated ABCG5 degradation in an E3 activity-dependent manner. Finally, RMA1, another E3 ubiquitin ligase, accelerated the degradation of both ABCG5 and ABCG8 via E3 activity-dependent manner. HRD1 and RMA1 may therefore be negative regulators of disease-associated transporter ABCG5/ABCG8. The findings also highlight the unexpected E3 activity-independent role of HRD1 in the regulation of N-glycosylation.
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81
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Abstract
Protein homoeostasis is a fundamental requirement for all living cells in order to survive in a dynamic surrounding. Proper levels of AIRAPL (arsenite-inducible RNA-associated protein-like protein) (ZFAND2B) are required in order to maintain cellular folding capacity in metazoans, and functional impairment of AIRAPL results in acceleration of aging and protein aggregation. However, the cellular roles of AIRAPL in this process are not known. In the present paper, we report that AIRAPL binds and forms a complex with p97 [VCP (valosin-containing protein)/Cdc48], Ubxd8 (ubiquitin regulatory X domain 8), Npl4-Ufd1, Derlin-1 and Bag6 on the ER (endoplasmic reticulum) membrane. In spite of the fact that AIRAPL complex partners are involved in the ERAD (ER-associated degradation) process, AIRAPL knockdown does not show any impairment in ERAD substrate degradation. However, translocation into the ER of a subset of ERAD- and non-ERAD-secreted proteins are regulated by AIRAPL. The ability to regulate translocation by the p97-AIRAPL complex is entirely dependent on the proteins' signal peptide. Our results demonstrate a p97 complex regulating translocation into the ER in a signal-peptide-dependent manner.
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82
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Yan L, Liu W, Zhang H, Liu C, Shang Y, Ye Y, Zhang X, Li W. Ube2g2-gp78-mediated HERP polyubiquitylation is involved in ER stress recovery. J Cell Sci 2014; 127:1417-27. [PMID: 24496447 DOI: 10.1242/jcs.135293] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
A large number of studies have focused on how individual organisms respond to a stress condition, but little attention has been paid to the stress recovery process, such as the endoplasmic reticulum (ER) stress recovery. Homocysteine-induced ER protein (HERP) was originally identified as a chaperone-like protein that is strongly induced upon ER stress. Here we show that, after ER stress induction, HERP is rapidly degraded by Ube2g2-gp78-mediated ubiquitylation and proteasomal degradation. The polyubiquitylation of HERP in vitro depends on a physical interaction between the CUE domain of gp78 and the ubiquitin-like (UBL) domain of HERP, which is essential for HERP degradation in vivo during ER stress recovery. We further show that although HERP promotes cell survival under ER stress, high levels of HERP expression reduce cell viability under oxidative stress conditions, suggesting that HERP plays a dual role in cellular stress adaptation. Together, these results establish the ubiquitin-proteasome-mediated degradation of HERP as a novel mechanism that fine-tunes the stress tolerance capacity of the cell.
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Affiliation(s)
- Long Yan
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
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83
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Leitman J, Shenkman M, Gofman Y, Shtern NO, Ben-Tal N, Hendershot LM, Lederkremer GZ. Herp coordinates compartmentalization and recruitment of HRD1 and misfolded proteins for ERAD. Mol Biol Cell 2014; 25:1050-60. [PMID: 24478453 PMCID: PMC3967970 DOI: 10.1091/mbc.e13-06-0350] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The unfolded protein response PERK branch induces recruitment of misfolded proteins and the ubiquitin ligase HRD1 to the ER-derived quality control compartment (ERQC), a staging ground for ER-associated degradation (ERAD). This is accomplished by up-regulation of homocysteine-induced ER protein (Herp), which recruits the ERAD complex at the ERQC. A functional unfolded protein response (UPR) is essential for endoplasmic reticulum (ER)-associated degradation (ERAD) of misfolded secretory proteins, reflecting the fact that some level of UPR activation must exist under normal physiological conditions. A coordinator of the UPR and ERAD processes has long been sought. We previously showed that the PKR-like, ER-localized eukaryotic translation initiation factor 2α kinase branch of the UPR is required for the recruitment of misfolded proteins and the ubiquitin ligase HRD1 to the ER-derived quality control compartment (ERQC), a staging ground for ERAD. Here we show that homocysteine-induced ER protein (Herp), a protein highly upregulated by this UPR branch, is responsible for this compartmentalization. Herp localizes to the ERQC, and our results suggest that it recruits HRD1, which targets to ERAD the substrate presented by the OS-9 lectin at the ERQC. Predicted overall structural similarity of Herp to the ubiquitin-proteasome shuttle hHR23, but including a transmembrane hairpin, suggests that Herp may function as a hub for membrane association of ERAD machinery components, a key organizer of the ERAD complex.
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Affiliation(s)
- Julia Leitman
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel Department of Biochemistry and Molecular Biology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, TN 38105
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84
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Huang CH, Chu YR, Ye Y, Chen X. Role of HERP and a HERP-related protein in HRD1-dependent protein degradation at the endoplasmic reticulum. J Biol Chem 2013; 289:4444-54. [PMID: 24366871 DOI: 10.1074/jbc.m113.519561] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Misfolded proteins of the endoplasmic reticulum (ER) are retrotranslocated to the cytosol and degraded by the proteasome via a process termed ER-associated degradation (ERAD). The precise mechanism of retrotranslocation is unclear. Here, we use several lumenal ERAD substrates targeted for degradation by the ubiquitin ligase HRD1 including SHH (sonic hedgehog) and NHK (null Hong Kong α1-antitrypsin) to study the geometry, organization, and regulation of the HRD1-containing ERAD machinery. We report a new HRD1-associated membrane protein named HERP2, which is homologous to the previously identified HRD1 partner HERP1. Despite sequence homology, HERP2 is constitutively expressed in cells, whereas HERP1 is highly induced by ER stress. We find that these proteins are required for efficient degradation of both glycosylated and nonglycosylated SHH proteins as well as NHK. In cells depleted of HERPs, SHH proteins are largely trapped inside the ER with a fraction of the stabilized SHH protein bound to the HRD1-SEL1L ligase complex. Ubiquitination of SHH is significantly attenuated in the absence of HERPs, suggesting a defect in retrotranslocation. Both HERP proteins interact with HRD1 through a region located in the cytosol. However, unlike its homolog in Saccharomyces cerevisiae, HERPs do not regulate HRD1 stability or oligomerization status. Instead, they help recruit DERL2 to the HRD1-SEL1L complex. Additionally, the UBL domain of HERP1 also seems to have a function independent of DERL2 recruitment in ERAD. Our studies have revealed a critical scaffolding function for mammalian HERP proteins that is required for forming an active retrotranslocation complex containing HRD1, SEL1L, and DERL2.
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Affiliation(s)
- Chih-Hsiang Huang
- From the Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli, Taiwan 35053, China
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85
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Behnke J, Hendershot LM. The large Hsp70 Grp170 binds to unfolded protein substrates in vivo with a regulation distinct from conventional Hsp70s. J Biol Chem 2013; 289:2899-907. [PMID: 24327659 DOI: 10.1074/jbc.m113.507491] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The Hsp70 superfamily is a ubiquitous chaperone class that includes conventional and large Hsp70s. BiP is the only conventional Hsp70 in the endoplasmic reticulum (ER) whose functions include: assisting protein folding, targeting misfolded proteins for degradation, and regulating the transducers of the unfolded protein response. The ER also possesses a single large Hsp70, the glucose-regulated protein of 170 kDa (Grp170). Like BiP it is an essential protein, but its cellular functions are not well understood. Here we show that Grp170 can bind directly to a variety of incompletely folded protein substrates in the ER, and as expected for a bona fide chaperone, it does not interact with folded secretory proteins. Our data demonstrate that Grp170 and BiP associate with similar molecular forms of two substrate proteins, but while BiP is released from unfolded substrates in the presence of ATP, Grp170 remains bound. In comparison to conventional Hsp70s, the large Hsp70s possess two unique structural features: an extended C-terminal α-helical domain and an unstructured loop in the putative substrate binding domain with an unknown function. We find that in the absence of the α-helical domain the interaction of Grp170 with substrates is reduced. In striking contrast, deletion of the unstructured loop results in increased binding to substrates, suggesting the presence of unique intramolecular mechanisms of control for the chaperone functions of large Hsp70s.
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Affiliation(s)
- Julia Behnke
- From the Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
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86
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Krzeszinski JY, Choe V, Shao J, Bao X, Cheng H, Luo S, Huo K, Rao H. XPC promotes MDM2-mediated degradation of the p53 tumor suppressor. Mol Biol Cell 2013; 25:213-21. [PMID: 24258024 PMCID: PMC3890342 DOI: 10.1091/mbc.e13-05-0293] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
XPC binds MDM2 ubiquitin ligase and participates in the MDM2-mediated p53 degradation. Furthermore, XPC overexpression stimulates p53 degradation following UV irradiation. Combined, the results suggest a key role of XPC in p53 degradation. Although ubiquitin receptor Rad23 has been implicated in bringing ubiquitylated p53 to the proteasome, how Rad23 recognizes p53 remains unclear. We demonstrate that XPC, a Rad23-binding protein, regulates p53 turnover. p53 protein in XPC-deficient cells remains ubiquitylated, but its association with the proteasome is drastically reduced, indicating that XPC regulates a postubiquitylation event. Furthermore, we found that XPC participates in the MDM2-mediated p53 degradation pathway via direct interaction with MDM2. XPC W690S pathogenic mutant is specifically defective for MDM2 binding and p53 degradation. p53 is known to become stabilized following UV irradiation but can be rendered unstable by XPC overexpression, underscoring a critical role of XPC in p53 regulation. Elucidation of the proteolytic role of XPC in cancer cells will help to unravel the detailed mechanisms underlying the coordination of DNA repair and proteolysis.
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Affiliation(s)
- Jing Yan Krzeszinski
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200433, People's Republic of China Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229 First Affiliated Hospital, Nanchang University, Jiangxi 330006, People's Republic of China
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87
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Petris G, Casini A, Sasset L, Cesaratto F, Bestagno M, Cereseto A, Burrone OR. CD4 and BST-2/tetherin proteins retro-translocate from endoplasmic reticulum to cytosol as partially folded and multimeric molecules. J Biol Chem 2013; 289:1-12. [PMID: 24257748 DOI: 10.1074/jbc.m113.512368] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CD4 and BST-2/Tetherin are cellular membrane proteins targeted to degradation by the HIV-1 protein Vpu. In both cases proteasomal degradation following recruitment into the ERAD pathway has been described. CD4 is a type I transmembrane glycoprotein, with four extracellular immunoglobulin-like domains containing three intrachain disulfide bridges. BST-2/Tetherin is an atypical type II transmembrane glycoprotein with an N-terminal transmembrane domain and a C-terminal glycophosphatidylinositol anchor, which dimerizes through three interchain bridges. We investigated spontaneous and Vpu-induced retro-translocation of CD4 and BST-2/Tetherin using our novel biotinylation technique in living cells to determine ER-to-cytosol retro-translocation of proteins. We found that CD4 retro-translocates with oxidized intrachain disulfide bridges, and only upon proteasomal inhibition does it accumulate in the cytosol as already reduced and deglycosylated molecules. Similarly, BST-2/Tetherin is first exposed to the cytosol as a dimeric oxidized complex and then becomes deglycosylated and reduced to monomers. These results raise questions on the required features of the putative retro-translocon, suggesting alternative retro-translocation mechanisms for membrane proteins in which complete cysteine reduction and unfolding are not always strictly required before ER to cytosol dislocation.
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Affiliation(s)
- Gianluca Petris
- From the International Centre for Genetic Engineering and Biotechnology (ICGEB), Padriciano 99, 34149 Trieste, Italy and
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88
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Bernasconi R, Galli C, Kokame K, Molinari M. Autoadaptive ER-associated degradation defines a preemptive unfolded protein response pathway. Mol Cell 2013; 52:783-93. [PMID: 24239290 DOI: 10.1016/j.molcel.2013.10.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 09/23/2013] [Accepted: 10/09/2013] [Indexed: 11/19/2022]
Abstract
Folding-defective proteins must be cleared efficiently from the endoplasmic reticulum (ER) to prevent perturbation of the folding environment and to maintain cellular proteostasis. Misfolded proteins engage dislocation machineries (dislocons) built around E3 ubiquitin ligases that promote their transport across the ER membrane, their polyubiquitylation, and their proteasomal degradation. Here, we report on the intrinsic instability of the HRD1 dislocon and the constitutive, rapid turnover of the scaffold protein HERP. We show that HRD1 dislocon integrity relies on the presence of HRD1 clients that interrupt, in a dose-dependent manner, the UBC6e/RNF5/p97/proteasome-controlled relay that controls HERP turnover. We propose that ER-associated degradation (ERAD) deploys autoadaptive regulatory pathways, collectively defined as ERAD tuning, to rapidly adapt degradation activity to misfolded protein load and to preempt the unfolded protein response (UPR) activation.
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Affiliation(s)
- Riccardo Bernasconi
- Institute for Research in Biomedicine, Protein Folding and Quality Control, 6500 Bellinzona, Switzerland
| | - Carmela Galli
- Institute for Research in Biomedicine, Protein Folding and Quality Control, 6500 Bellinzona, Switzerland
| | - Koichi Kokame
- Department of Molecular Pathogenesis, National Cerebral and Cardiovascular Center, Osaka 565-8565, Japan
| | - Maurizio Molinari
- Institute for Research in Biomedicine, Protein Folding and Quality Control, 6500 Bellinzona, Switzerland; Ecole Polytechnique Fédérale de Lausanne, School of Life Sciences, 1015 Lausanne, Switzerland.
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89
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Quiroga C, Gatica D, Paredes F, Bravo R, Troncoso R, Pedrozo Z, Rodriguez AE, Toro B, Chiong M, Vicencio JM, Hetz C, Lavandero S. Herp depletion protects from protein aggregation by up-regulating autophagy. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:3295-3305. [PMID: 24120520 DOI: 10.1016/j.bbamcr.2013.09.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 08/21/2013] [Accepted: 09/10/2013] [Indexed: 01/04/2023]
Abstract
Herp is an endoplasmic reticulum (ER) stress inducible protein that participates in the ER-associated protein degradation (ERAD) pathway. However, the contribution of Herp to other protein degradation pathways like autophagy and its connection to other types of stress responses remain unknown. Here we report that Herp regulates autophagy to clear poly-ubiquitin (poly-Ub) protein aggregates. Proteasome inhibition and glucose starvation (GS) led to a high level of poly-Ub protein aggregation that was drastically reduced by stably knocking down Herp (shHerp cells). The enhanced removal of poly-Ub inclusions protected cells from death caused by glucose starvation. Under basal conditions and increasingly after stress, higher LC3-II levels and GFP-LC3 puncta were observed in shHerp cells compared to control cells. Herp knockout cells displayed basal up-regulation of two essential autophagy regulators-Atg5 and Beclin-1, leading to increased autophagic flux. Beclin-1 up-regulation was due to a reduction in Hrd1 dependent proteasomal degradation, and not at transcriptional level. The consequent higher autophagic flux was necessary for the clearance of aggregates and for cell survival. We conclude that Herp operates as a relevant factor in the defense against glucose starvation by modulating autophagy levels. These data may have important implications due to the known up-regulation of Herp in pathological states such as brain and heart ischemia, both conditions associated to acute nutritional stress.
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Affiliation(s)
- Clara Quiroga
- Advanced Center for Chronic Diseases (ACCDiS) & Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago 8380492, Chile; Harvard School of Public Health, Boston, MA, USA
| | - Damian Gatica
- Advanced Center for Chronic Diseases (ACCDiS) & Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago 8380492, Chile
| | - Felipe Paredes
- Advanced Center for Chronic Diseases (ACCDiS) & Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago 8380492, Chile
| | - Roberto Bravo
- Advanced Center for Chronic Diseases (ACCDiS) & Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago 8380492, Chile
| | - Rodrigo Troncoso
- Advanced Center for Chronic Diseases (ACCDiS) & Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago 8380492, Chile
| | - Zully Pedrozo
- Advanced Center for Chronic Diseases (ACCDiS) & Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago 8380492, Chile
| | - Andrea E Rodriguez
- Advanced Center for Chronic Diseases (ACCDiS) & Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago 8380492, Chile
| | - Barbra Toro
- Advanced Center for Chronic Diseases (ACCDiS) & Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago 8380492, Chile
| | - Mario Chiong
- Advanced Center for Chronic Diseases (ACCDiS) & Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago 8380492, Chile
| | - Jose Miguel Vicencio
- Advanced Center for Chronic Diseases (ACCDiS) & Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago 8380492, Chile; The Hatter Cardiovascular Institute, University College London, 67 Chenies Mews, London WC1E 6HX, UK
| | - Claudio Hetz
- Advanced Center for Chronic Diseases (ACCDiS) & Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago 8380492, Chile; Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago 8380492, Chile; The Hatter Cardiovascular Institute, University College London, 67 Chenies Mews, London WC1E 6HX, UK.
| | - Sergio Lavandero
- Advanced Center for Chronic Diseases (ACCDiS) & Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago 8380492, Chile; Department of Internal Medicine (Cardiology Division), University of Texas Southwestern Medical Center, Dallas, TX, USA.
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90
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Chen SF, Wu CH, Lee YM, Tam K, Tsai YC, Liou JY, Shyue SK. Caveolin-1 interacts with Derlin-1 and promotes ubiquitination and degradation of cyclooxygenase-2 via collaboration with p97 complex. J Biol Chem 2013; 288:33462-9. [PMID: 24089527 DOI: 10.1074/jbc.m113.521799] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Caveolin-1 (Cav-1) interacts with and mediates protein trafficking and various cellular functions. Derlin-1 is a candidate for the retrotranslocation channel of endoplasmic reticulum proteins. However, little is known about how Derlin-1 mediates glycosylated protein degradation. Here, we identified Cav-1 as a key player in Derlin-1- and p97-mediated cyclooxygenase 2 (COX-2) ubiquitination and degradation. Derlin-1 augmented the interaction of Cav-1 and COX-2 and mediated the degradation of COX-2 in a COX-2 C terminus-dependent manner. Suppression of Cav-1 decreased the ubiquitination of COX-2, and mutation of Asn-594 to Ala to disrupt N-glycosylation at the C terminus of COX-2 reduced the interaction of COX-2 with Cav-1 but not Derlin-1. Moreover, suppression of p97 increased the ubiquitination of COX-2 and up-regulated COX-2 but not COX-1. Cav-1 enhanced the interaction of p97 with Ufd1 and Derlin-1 and collaborated with p97 to interact with COX-2. Cav-1 may be a cofactor in the interaction of Derlin-1 and N-glycosylated COX-2 and may facilitate Derlin-1- and p97 complex-mediated COX-2 ubiquitination, retrotranslocation, and degradation.
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Affiliation(s)
- Shu-Fen Chen
- From the Cardiovascular Division, Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
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91
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Olzmann JA, Kopito RR, Christianson JC. The mammalian endoplasmic reticulum-associated degradation system. Cold Spring Harb Perspect Biol 2013; 5:cshperspect.a013185. [PMID: 23232094 DOI: 10.1101/cshperspect.a013185] [Citation(s) in RCA: 253] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The endoplasmic reticulum (ER) is the site of synthesis for nearly one-third of the eukaryotic proteome and is accordingly endowed with specialized machinery to ensure that proteins deployed to the distal secretory pathway are correctly folded and assembled into native oligomeric complexes. Proteins failing to meet this conformational standard are degraded by ER-associated degradation (ERAD), a complex process through which folding-defective proteins are selected and ultimately degraded by the ubiquitin-proteasome system. ERAD proceeds through four tightly coupled steps involving substrate selection, dislocation across the ER membrane, covalent conjugation with polyubiquitin, and proteasomal degradation. The ERAD machinery shows a modular organization with central ER membrane-embedded ubiquitin ligases linking components responsible for recognition in the ER lumen to the ubiquitin-proteasome system in the cytoplasm. The core ERAD machinery is highly conserved among eukaryotes and much of our basic understanding of ERAD organization has been derived from genetic and biochemical studies of yeast. In this article we discuss how the core ERAD machinery is organized in mammalian cells.
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Affiliation(s)
- James A Olzmann
- Department of Biology, Stanford University, Stanford, California 94305, USA
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92
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Ushioda R, Hoseki J, Nagata K. Glycosylation-independent ERAD pathway serves as a backup system under ER stress. Mol Biol Cell 2013; 24:3155-63. [PMID: 23966469 PMCID: PMC3806662 DOI: 10.1091/mbc.e13-03-0138] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Glycosylated and nonglycosylated proteins misfolded in the ER are degraded by discrete but interchangeable pathways in the ERAD system. Disulfide reductase ERdj5 plays a central role in both pathways through the complex formation with EDEM and/or BiP. The nonglycoprotein ERAD pathway serves as a backup system under ER stress conditions. During endoplasmic reticulum (ER)–associated degradation (ERAD), terminally misfolded proteins are retrotranslocated from the ER to the cytosol and degraded by the ubiquitin-proteasome system. Misfolded glycoproteins are recognized by calnexin and transferred to EDEM1, followed by the ER disulfide reductase ERdj5 and the BiP complex. The mechanisms involved in ERAD of nonglycoproteins, however, are poorly understood. Here we show that nonglycoprotein substrates are captured by BiP and then transferred to ERdj5 without going through the calnexin/EDEM1 pathway; after cleavage of disulfide bonds by ERdj5, the nonglycoproteins are transferred to the ERAD scaffold protein SEL1L by the aid of BiP for dislocation into the cytosol. When glucose trimming of the N-glycan groups of the substrates is inhibited, glycoproteins are also targeted to the nonglycoprotein ERAD pathway. These results indicate that two distinct pathways for ERAD of glycoproteins and nonglycoproteins exist in mammalian cells, and these pathways are interchangeable under ER stress conditions.
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Affiliation(s)
- Ryo Ushioda
- Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan
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93
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MHC class I molecules are preferentially ubiquitinated on endoplasmic reticulum luminal residues during HRD1 ubiquitin E3 ligase-mediated dislocation. Proc Natl Acad Sci U S A 2013; 110:14290-5. [PMID: 23929775 DOI: 10.1073/pnas.1303380110] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Misfolded MHC class I heavy chains (MHC I HCs) are targeted for endoplasmic reticulum (ER)-associated degradation (ERAD) by the ubiquitin E3 ligase HRD1, and E2 ubiquitin conjugating enzyme UBE2J1, and represent one of the few known endogenous ERAD substrates. The mechanism by which misfolded proteins are dislocated across the ER membrane into the cytosol is unclear. Here, we investigate the requirements for MHC I ubiquitination and degradation and show that endogenous misfolded MHC I HCs are recognized in the ER lumen by EDEM1 in a glycan-dependent manner and targeted to the core SEL1L/HRD1/UBE2J1 complex. A soluble MHC I HC lacking its transmembrane domain and cytosolic tail uses the same ERAD components and is degraded as efficiently as wild-type MHC I. Unexpectedly, HRD1-dependent polyubiquitination is preferentially targeted to the ER luminal domain of full-length MHC I HCs, despite the presence of an exposed cytosolic C-terminal tail. MHC I luminal domain ubiquitination occurs before p97 ATPase-mediated extraction from the ER membrane and can be targeted to nonlysine, as well as lysine, residues. A subset of integral membrane proteins, therefore, requires an early dislocation event to expose part of their luminal domain to the cytosol, before HRD1-mediated polyubiquitination and dislocation.
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94
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Wong N, Morahan G, Stathopoulos M, Proietto J, Andrikopoulos S. A novel mechanism regulating insulin secretion involving Herpud1 in mice. Diabetologia 2013; 56:1569-76. [PMID: 23620059 DOI: 10.1007/s00125-013-2908-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Accepted: 03/18/2013] [Indexed: 11/24/2022]
Abstract
AIMS/HYPOTHESIS Type 2 diabetes results from beta cell dysfunction after prolonged physiological stress, which causes oversecretion of insulin. We recently found that insulin hypersecretion is mediated by at least two genes. Among mouse models of type 2 diabetes, the DBA/2 mouse strain is more susceptible to diabetes than is the C57BL/6J (B6J) strain. One distinctive feature of the DBA/2 mouse is that it hypersecretes insulin, independent of changes in insulin sensitivity; we identified Nnt as a gene responsible for this trait. METHODS To identify the other gene(s) affecting insulin hypersecretion, we tested a panel of recombinant inbred BXD strains, which have different combinations of B6 and DBA/2 alleles. RESULTS We found that 25% of the BXD strains hypersecreted insulin in response to glucose. Microarray profiling of islets from high- and low-secretor strains showed that at least four genes were differentially expressed. One gene was consistently underexpressed in islets from both DBA/2 and the high-secretor BXD strains. This gene (Herpud1 or Herp) encodes the 54 kDa endoplasmic reticulum stress-inducible protein (HERP) that resides in the integral endoplasmic reticulum membrane. To test directly whether Herpud1 can interact with Nnt, Herpud1 was either knocked down or overexpressed in MIN6 cells. These results showed that when Herpud1 was suppressed, Nnt expression was reduced, while overexpression of Herpud1 led to increased Nnt expression. Furthermore, Herpud1 suppression resulted in significantly decreased glucose-stimulated insulin secretion in the DBA/2 islets but not B6J islets. CONCLUSIONS/INTERPRETATION We conclude that Herpud1 regulates insulin secretion via control of Nnt expression.
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Affiliation(s)
- N Wong
- Department of Medicine (Austin Health), Austin Hospital, University of Melbourne, Heidelberg Heights, Melbourne, Victoria, 3084, Australia.
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95
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Athanasiou D, Aguilà M, Bevilacqua D, Novoselov SS, Parfitt DA, Cheetham ME. The cell stress machinery and retinal degeneration. FEBS Lett 2013; 587:2008-17. [PMID: 23684651 PMCID: PMC4471140 DOI: 10.1016/j.febslet.2013.05.020] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 05/01/2013] [Accepted: 05/02/2013] [Indexed: 12/12/2022]
Abstract
Retinal degenerations are a group of clinically and genetically heterogeneous disorders characterised by progressive loss of vision due to neurodegeneration. The retina is a highly specialised tissue with a unique architecture and maintaining homeostasis in all the different retinal cell types is crucial for healthy vision. The retina can be exposed to a variety of environmental insults and stress, including light-induced damage, oxidative stress and inherited mutations that can lead to protein misfolding. Within retinal cells there are different mechanisms to cope with disturbances in proteostasis, such as the heat shock response, the unfolded protein response and autophagy. In this review, we discuss the multiple responses of the retina to different types of stress involved in retinal degenerations, such as retinitis pigmentosa, age-related macular degeneration and glaucoma. Understanding the mechanisms that maintain and re-establish proteostasis in the retina is important for developing new therapeutic approaches to fight blindness.
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Affiliation(s)
| | - Monica Aguilà
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
| | - Dalila Bevilacqua
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
| | | | - David A. Parfitt
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
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96
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Ono Y, Tanaka H, Tsuruma K, Shimazawa M, Hara H. A sigma-1 receptor antagonist (NE-100) prevents tunicamycin-induced cell death via GRP78 induction in hippocampal cells. Biochem Biophys Res Commun 2013; 434:904-9. [PMID: 23618865 DOI: 10.1016/j.bbrc.2013.04.055] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 04/12/2013] [Indexed: 02/01/2023]
Abstract
Endoplasmic reticulum (ER) stress is involved in various diseases such as ischemia, Alzheimer's disease, and Parkinson's disease. The widely used selective sigma-1 receptor antagonist, N, N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)-phenyl]-ethylamine monohydrochloride (NE-100), has been shown to suppress ischemia-induced neuronal cell death in the murine hippocampus. In the present study, we investigated whether NE-100 might suppress neuronal cell death that is induced by ER stress in ischemic injury. These studies show that NE-100 protected the ER stress-induced cell death of murine hippocampal HT22 cells, but not the oxidative stress-induced cell death. This suggests that NE-100 may have a protective effect on the ER. However, another sigma-1 receptor antagonist (BD1047) did not suppress ER stress-induced cell death. In addition, NE-100 attenuated the upregulation of C/EBP homologous protein (CHOP) induced by ER stress and upregulated the expression of both the 50-kDa activating transcription factor 6 (p50ATF6) and the 78-kDa glucose-regulated protein (GRP78). However, NE-100 did not impact the expression of phosphorylated eukaryotic initiation factor 2α (p-eIF2α) nor splicing of X-box-binding protein 1 (XBP-1). These findings suggest that NE-100 suppresses ER stress-induced cell death via CHOP expression by the upregulation of GRP78 through ATF6 pathway, independent sigma-1 receptor antagonist effect.
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Affiliation(s)
- Yoko Ono
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan
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97
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Needham PG, Brodsky JL. How early studies on secreted and membrane protein quality control gave rise to the ER associated degradation (ERAD) pathway: the early history of ERAD. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2447-57. [PMID: 23557783 DOI: 10.1016/j.bbamcr.2013.03.018] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 03/18/2013] [Accepted: 03/21/2013] [Indexed: 12/31/2022]
Abstract
All newly synthesized proteins are subject to quality control check-points, which prevent aberrant polypeptides from harming the cell. For proteins that ultimately reside in the cytoplasm, components that also reside in the cytoplasm were known for many years to mediate quality control. Early biochemical and genetic data indicated that misfolded proteins were selected by molecular chaperones and then targeted to the proteasome (in eukaryotes) or to proteasome-like particles (in bacteria) for degradation. What was less clear was how secreted and integral membrane proteins, which in eukaryotes enter the endoplasmic reticulum (ER), were subject to quality control decisions. In this review, we highlight early studies that ultimately led to the discovery that secreted and integral membrane proteins also utilize several components that constitute the cytoplasmic quality control machinery. This component of the cellular quality control pathway is known as ER associated degradation, or ERAD. This article is part of a Special Issue entitled: Functional and structural diversity of endoplasmic reticulum.
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Affiliation(s)
- Patrick G Needham
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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98
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Tiwari A, Schuiki I, Zhang L, Allister EM, Wheeler MB, Volchuk A. SDF2L1 interacts with the ER-associated degradation machinery and retards the degradation of mutant proinsulin in pancreatic β-cells. J Cell Sci 2013; 126:1962-8. [PMID: 23444373 DOI: 10.1242/jcs.117374] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Stromal cell-derived factor 2-like 1 (SDF2L1) is an endoplasmic reticulum (ER)-localized protein whose function is undefined. Here we show that SDF2L1 protein levels are increased in response to ER stress-inducing compounds, but not other cell stressors that we tested in insulinoma cell lines. SDF2L1 protein levels were also induced by expression of misfolded proinsulin in insulinoma cells and in islets from diabetic mice. Immunoprecipitation and binding assays demonstrated that SDF2L1 interacts with the ER chaperone GRP78/BiP, the ER-associated degradation (ERAD) machinery and with misfolded proinsulin. Unexpectedly, knockdown of SDF2L1 in INS-1 (insulin 2 C96Y-GFP) cells increased the degradation kinetics of mutant proinsulin, suggesting that SDF2L1 regulates substrate availability for the ERAD system. We suggest that SDF2L1 increases the time that misfolded proteins have to achieve a correctly folded conformation and thus that SDF2L1 can act as a buffer for substrate availability for ERAD in pancreatic β-cells.
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Affiliation(s)
- Akansha Tiwari
- Division of Cellular and Molecular Biology, Toronto General Research Institute, University Health Network, ON M5G 1L7, Canada
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99
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Cleaning up: ER-associated degradation to the rescue. Cell 2013; 151:1163-7. [PMID: 23217703 DOI: 10.1016/j.cell.2012.11.012] [Citation(s) in RCA: 266] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 10/05/2012] [Accepted: 11/01/2012] [Indexed: 11/22/2022]
Abstract
All cellular proteins are subject to quality control "decisions," which help to prevent or delay a myriad of diseases. Quality control within the secretory pathway creates a special challenge, as aberrant polypeptides are recognized and returned to the cytoplasm for proteasomal degradation. This process is termed endoplasmic-reticulum (ER)-associated degradation (ERAD).
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100
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Leitman J, Ron E, Ogen-Shtern N, Lederkremer GZ. Compartmentalization of Endoplasmic Reticulum Quality Control and ER-Associated Degradation Factors. DNA Cell Biol 2013. [DOI: 10.1089/dna.2012.1889] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Julia Leitman
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Efrat Ron
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Navit Ogen-Shtern
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Gerardo Z. Lederkremer
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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