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Forouhan M, Mori K, Boot-Handford RP. Paradoxical roles of ATF6α and ATF6β in modulating disease severity caused by mutations in collagen X. Matrix Biol 2018; 70:50-71. [PMID: 29522813 PMCID: PMC6090092 DOI: 10.1016/j.matbio.2018.03.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 03/02/2018] [Accepted: 03/03/2018] [Indexed: 01/05/2023]
Abstract
Whilst the role of ATF6α in modulating the unfolded protein response (UPR) has been well documented, the function of its paralogue ATF6β is less well understood. Using knockdown in cell culture and gene ablation in mice we have directly compared the roles of ATF6α & β in responding to the increased ER stress induced by mutant forms of type X collagen that cause the ER stress-associated metaphyseal chondrodysplasia type Schmid (MCDS). ATF6α more efficiently deals with the disease-associated ER stress in the absence of ATF6β and conversely, ATF6β is less effective in the absence of ATF6α. Furthermore, disease severity in vivo is increased by ATF6α ablation and decreased by ATF6β ablation. In addition, novel functions for each paralogue are described including an ATF6β-specific role in controlling growth plate chondrocyte proliferation. The clear demonstration of the intimate relationship of the two ATF6 isoforms and how ATF6β can moderate the activity of ATF6α and vice versa is of great significance for understanding the UPR mechanism. The activities of both ATF6 isoforms and their separate roles need consideration when deciding how to target increased ER stress as a means of treating MCDS and other ER stress-associated diseases.
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Affiliation(s)
- M Forouhan
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, Manchester, UK
| | - K Mori
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - R P Boot-Handford
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, Manchester, UK.
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2
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Liu CY, Hsu CC, Huang TT, Lee CH, Chen JL, Yang SH, Jiang JK, Chen WS, Lee KD, Teng HW. ER stress-related ATF6 upregulates CIP2A and contributes to poor prognosis of colon cancer. Mol Oncol 2018; 12:1706-1717. [PMID: 30063110 PMCID: PMC6166000 DOI: 10.1002/1878-0261.12365] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 06/27/2018] [Accepted: 07/22/2018] [Indexed: 01/20/2023] Open
Abstract
Endoplasmic reticulum (ER) stress is an adaptive response to various stress conditions and plays emerging roles in cancer. Activating transcription factor 6 (ATF6), one of the three major ER stress transducers, has been shown to contribute to chemoresistance by altering cancer cell survival. Cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncogene, and its expression has been correlated with the prognosis of patients with cancer. In this study, we aimed to explore the relationship between ER stress‐related ATF signaling and CIP2A. We found that CIP2A expression was positively correlated with ATF6 expression by analyzing publicly available RNA sequence data of patients with colorectal cancer (The Cancer Genome Atlas, TCGA). In addition, we demonstrated that tunicamycin‐induced ER stress in vitro upregulated ATF6 and CIP2A. Mechanistically, we found that ATF6 directly bound to the CIP2A promoter and induced CIP2A gene expression, which contributed to colon cancer cell survival. Furthermore, knockdown of CIP2A reduced the viability of cells under ER stress. Most importantly, immunohistochemical analysis of a tissue microarray from a colon cancer patient cohort showed that higher expression levels of ATF6 and CIP2A were associated with a trend toward poor prognosis. Taken together, our results show that ER stress‐related ATF6 upregulates CIP2A and contributes to the prognosis of colon cancer. Targeting CIP2A may disrupt ER stress‐mediated colon cancer cell survival and thus improve the prognosis of patients with colon cancer.
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Affiliation(s)
- Chun-Yu Liu
- Division of Medical Oncology, Department of Oncology, Center for Immuno-Oncology, Taipei Veterans General Hospital, Taiwan.,School of Medicine, National Yang-Ming University, Taipei, Taiwan.,Comprehensive Breast Health Center, Taipei Veterans General Hospital, Taiwan.,Division of Transfusion Medicine, Department of Medicine, Taipei Veterans General Hospital, Taiwan
| | - Chia-Chi Hsu
- Division of Medical Oncology, Department of Oncology, Center for Immuno-Oncology, Taipei Veterans General Hospital, Taiwan.,Comprehensive Breast Health Center, Taipei Veterans General Hospital, Taiwan
| | - Tzu-Ting Huang
- Division of Medical Oncology, Department of Oncology, Center for Immuno-Oncology, Taipei Veterans General Hospital, Taiwan.,Comprehensive Breast Health Center, Taipei Veterans General Hospital, Taiwan
| | - Chia-Han Lee
- Division of Medical Oncology, Department of Oncology, Center for Immuno-Oncology, Taipei Veterans General Hospital, Taiwan
| | - Ji-Lin Chen
- Division of Medical Oncology, Department of Oncology, Center for Immuno-Oncology, Taipei Veterans General Hospital, Taiwan.,Comprehensive Breast Health Center, Taipei Veterans General Hospital, Taiwan
| | - Shung-Haur Yang
- School of Medicine, National Yang-Ming University, Taipei, Taiwan.,Division of Colon and Rectum Surgery, Department of Surgery, Taipei Veterans General Hospital, Taiwan.,Department of Surgery, National Yang-Ming University Hospital, Yilan, Taiwan
| | - Jeng-Kai Jiang
- School of Medicine, National Yang-Ming University, Taipei, Taiwan.,Division of Colon and Rectum Surgery, Department of Surgery, Taipei Veterans General Hospital, Taiwan
| | - Wei-Shone Chen
- School of Medicine, National Yang-Ming University, Taipei, Taiwan.,Division of Colon and Rectum Surgery, Department of Surgery, Taipei Veterans General Hospital, Taiwan
| | - Kuan-Der Lee
- Division of Hematology and Oncology, Department of Internal Medicine, Taipei Medical University Hospital, Taiwan.,School of Medicine, Taipei Medical University, Taiwan
| | - Hao-Wei Teng
- Division of Medical Oncology, Department of Oncology, Center for Immuno-Oncology, Taipei Veterans General Hospital, Taiwan.,School of Medicine, National Yang-Ming University, Taipei, Taiwan
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Yuan K, He HH, Zhang CZ, Li XY, Weng SP, He JG, Chen YH. Litopenaeus vannamei activating transcription factor 6 alpha gene involvement in ER-stress response and white spot symptom virus infection. FISH & SHELLFISH IMMUNOLOGY 2017; 70:129-139. [PMID: 28882789 DOI: 10.1016/j.fsi.2017.09.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 08/06/2017] [Accepted: 09/03/2017] [Indexed: 06/07/2023]
Abstract
A previous study found that inositol-requiring enzyme-1-X-box binding protein 1 (IRE1-XBP1) pathway and the protein kinase RNA (PKR)-like ER kinase-eIF2α (PERK-eIF2α) pathway of shrimp play roles in the unfolded protein response (UPR). And they also be proved that was involved in white spot symptom virus (WSSV) infection. Yet the functions of the third branch in shrimp UPR are still unclear. In this study, we showed that upon UPR activation, activating transcription factor 6 alpha (LvATF6α) of Litopenaeus vannamei was cleaved and transferred from the cytoplasm to the nucleus in 293T cells, indicating that the ATF6 pathway in shrimp is also a branch of UPR. Furthermore, LvATF6α could reduce the apoptosis rate of Drosophila Schneider 2 (S2) cells treated with actinomycin, and knock-down expression of LvATF6α increased the apoptosis rate of shrimp hemocytes. In vivo testing revealed that the short from LvATF6α (LvATF6α-s) was obviously increased after UPR activation or WSSV infection, indicating that the ATF6 pathway was activated in L. vannamei gills under such circumstances. Moreover, knock-down expression of LvATF6α could reduce the cumulative mortality and WSSV copy number in WSSV-infected shrimp. Further study revealed that WSSV may profit from shrimp ATF6 pathway activation in two aspects. First, LvATF6α-s significantly upregulated the expression of the WSSV genes (wsv023, wsv045, wsv083, wsv129, wsv222, wsv249, and wsv343). Second, LvATF6α-s inhibited apoptosis by negatively regulating the apoptosis signal-regulating kinase 1 - (c-Jun N-terminal kinase) pathway. All of these evidences suggested that the ATF6 pathway is a member of the L. vannamei UPR, and it is also engaged in WSSV infection.
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Affiliation(s)
- Kai Yuan
- School of Life Sciences, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China; State Key Laboratory for Biocontrol, MOE Key Laboratory of Aquatic Product Safety, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China
| | - Hong-Hui He
- School of Life Sciences, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China; State Key Laboratory for Biocontrol, MOE Key Laboratory of Aquatic Product Safety, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China
| | - Chao-Zheng Zhang
- Guangdong Provincial Center for Disease Control and Prevention, 160 QunXian Road, Guangzhou 511430, PR China
| | - Xiao-Yun Li
- School of Life Sciences, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China
| | - Shao-Ping Weng
- School of Life Sciences, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China; State Key Laboratory for Biocontrol, MOE Key Laboratory of Aquatic Product Safety, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China
| | - Jian-Guo He
- School of Life Sciences, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China; Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, South China Sea Bio-Resource Exploitation and Protection Collaborative Innovation Center (SCS-REPIC), School of Marine Sciences, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China; State Key Laboratory for Biocontrol, MOE Key Laboratory of Aquatic Product Safety, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China
| | - Yi-Hong Chen
- Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, South China Sea Bio-Resource Exploitation and Protection Collaborative Innovation Center (SCS-REPIC), School of Marine Sciences, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China; State Key Laboratory for Biocontrol, MOE Key Laboratory of Aquatic Product Safety, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China.
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Pappalardo Z, Gambhir Chopra D, Hennings TG, Richards H, Choe J, Yang K, Baeyens L, Ang K, Chen S, Arkin M, German MS, McManus MT, Ku GM. A Whole-Genome RNA Interference Screen Reveals a Role for Spry2 in Insulin Transcription and the Unfolded Protein Response. Diabetes 2017; 66:1703-1712. [PMID: 28246293 PMCID: PMC5440024 DOI: 10.2337/db16-0962] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Accepted: 02/16/2017] [Indexed: 12/18/2022]
Abstract
Insulin production by the pancreatic β-cell is required for normal glucose homeostasis. While key transcription factors that bind to the insulin promoter are known, relatively little is known about the upstream regulators of insulin transcription. Using a whole-genome RNA interference screen, we uncovered 26 novel regulators of insulin transcription that regulate diverse processes including oxidative phosphorylation, vesicle traffic, and the unfolded protein response (UPR). We focused on Spry2-a gene implicated in human type 2 diabetes by genome-wide association studies but without a clear connection to glucose homeostasis. We showed that Spry2 is a novel UPR target and its upregulation is dependent on PERK. Knockdown of Spry2 resulted in reduced expression of Serca2, reduced endoplasmic reticulum calcium levels, and induction of the UPR. Spry2 deletion in the adult mouse β-cell caused hyperglycemia and hypoinsulinemia. Our study greatly expands the compendium of insulin promoter regulators and demonstrates a novel β-cell link between Spry2 and human diabetes.
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Affiliation(s)
- Zachary Pappalardo
- Diabetes Center, University of California, San Francisco, San Francisco, CA
| | | | - Thomas G Hennings
- Diabetes Center, University of California, San Francisco, San Francisco, CA
- Biomedical Sciences Graduate Program, University of California, San Francisco, San Francisco, CA
| | - Hunter Richards
- Diabetes Center, University of California, San Francisco, San Francisco, CA
| | - Justin Choe
- Diabetes Center, University of California, San Francisco, San Francisco, CA
| | - Katherine Yang
- Diabetes Center, University of California, San Francisco, San Francisco, CA
| | - Luc Baeyens
- Diabetes Center, University of California, San Francisco, San Francisco, CA
| | - Kenny Ang
- Small Molecule Discovery Center, University of California, San Francisco, San Francisco, CA
| | - Steven Chen
- Small Molecule Discovery Center, University of California, San Francisco, San Francisco, CA
| | - Michelle Arkin
- Small Molecule Discovery Center, University of California, San Francisco, San Francisco, CA
| | - Michael S German
- Diabetes Center, University of California, San Francisco, San Francisco, CA
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Francisco, San Francisco, CA
| | - Michael T McManus
- Diabetes Center, University of California, San Francisco, San Francisco, CA
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA
| | - Gregory M Ku
- Diabetes Center, University of California, San Francisco, San Francisco, CA
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Francisco, San Francisco, CA
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Odisho T, Zhang L, Volchuk A. ATF6β regulates the Wfs1 gene and has a cell survival role in the ER stress response in pancreatic β-cells. Exp Cell Res 2014; 330:111-22. [PMID: 25447309 DOI: 10.1016/j.yexcr.2014.10.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 10/02/2014] [Accepted: 10/05/2014] [Indexed: 01/20/2023]
Abstract
Endoplasmic reticulum (ER) stress is implicated in pancreatic β-cell dysfunction and death resulting in type 2 diabetes. Activating transcription factor 6 (ATF6) is an essential component of the Unfolded Protein Response (UPR) and consists of two isoforms, ATF6α and ATF6β. Here we investigated the role of ATF6β. ATF6β mRNA was detected in pancreatic β-cell lines and rodent and human islets. We also detected ATF6β protein and production of the active form (ATF6βp60) in response to ER stress. Knock-down of ATF6β in INS-1 832/13 insulinoma cells did not affect mRNA induction of several major UPR genes in response to ER stress, suggesting ATF6β is not essential for the basic UPR. Expressing active ATF6βp60 or ATF6αp50 followed by microarray analysis showed that they regulate similar UPR genes, although some genes such as Wfs1 are ATF6β-specific. ATF6β, but not ATF6α, is able to bind the Wfs1 promoter and induce Wfs1 gene and protein expression. Knock-down of ATF6β increased the susceptibility of β-cells to ER stress-induced apoptosis, while overexpression of active ATF6βp60 reduced apoptosis. Thus, ATF6β is not essential for induction of most UPR genes, but is required to maintain cell survival in β-cells undergoing chronic ER stress, which in part relates to its ability to induce Wfs1, a pro-survival gene.
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Affiliation(s)
- Tanya Odisho
- Division of Advanced Diagnostics - Metabolism, Toronto General Research Institute, University Health Network, Canada; Department of Physiology, University of Toronto, Canada
| | - Liling Zhang
- Division of Advanced Diagnostics - Metabolism, Toronto General Research Institute, University Health Network, Canada
| | - Allen Volchuk
- Division of Advanced Diagnostics - Metabolism, Toronto General Research Institute, University Health Network, Canada; Department of Physiology, University of Toronto, Canada; Department of Biochemistry, University of Toronto, Canada.
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Biden TJ, Boslem E, Chu KY, Sue N. Lipotoxic endoplasmic reticulum stress, β cell failure, and type 2 diabetes mellitus. Trends Endocrinol Metab 2014; 25:389-98. [PMID: 24656915 DOI: 10.1016/j.tem.2014.02.003] [Citation(s) in RCA: 155] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2013] [Revised: 02/12/2014] [Accepted: 02/19/2014] [Indexed: 02/06/2023]
Abstract
Failure of the unfolded protein response (UPR) to maintain optimal folding of pro-insulin in the endoplasmic reticulum (ER) leads to unresolved ER stress and β cell death. This contributes not only to some rare forms of diabetes, but also to type 2 diabetes mellitus (T2DM). Many key findings, elaborated over the past decade, are based on the lipotoxicity model, entailing chronic exposure of β cells to elevated levels of fatty acids (FAs). Here, we update recent progress on how FAs initiate ER stress, particularly via disruption of protein trafficking, and how this leads to apoptosis. We also highlight differences in how β cells are impacted by the classic UPR, versus the more selective UPR that arises as part of a broader response to lipotoxicity.
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Affiliation(s)
- Trevor J Biden
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia.
| | - Ebru Boslem
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Kwan Yi Chu
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Nancy Sue
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
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Teodoro T, Odisho T, Sidorova E, Volchuk A. Pancreatic β-cells depend on basal expression of active ATF6α-p50 for cell survival even under nonstress conditions. Am J Physiol Cell Physiol 2011; 302:C992-1003. [PMID: 22189555 DOI: 10.1152/ajpcell.00160.2011] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Activating transcription factor 6 (ATF6) is one of three principle endoplasmic reticulum (ER) stress response proteins and becomes activated when ER homeostasis is perturbed. ATF6 functions to increase ER capacity by stimulating transcription of ER-resident chaperone genes such as GRP78. Using an antibody that recognizes active ATF6α-p50, we found that active ATF6α was detected in insulinoma cells and rodent islets even under basal conditions and the levels were further increased by ER stress. To examine the function of ATF6α-p50, we depleted endogenous ATF6α-p50 levels using small interfering RNA in insulinoma cells. Knockdown of endogenous ATF6α-p50 levels by ∼60% resulted in a reduction in the steady-state levels of GRP78 mRNA and protein levels in nonstressed cells. Furthermore, ATF6α knockdown resulted in an apoptotic phenotype. We hypothesized that removal of the ATF6α branch of the unfolded protein response (UPR) would result in ER stress. However, neither the PKR-like endoplasmic reticulum kinase (PERK), nor the inositol requiring enzyme 1 (IRE1) pathways of the UPR were significantly activated in ATF6α knockdown cells, although these cells were more sensitive to ER stress-inducing compounds. Interestingly, phosphorylation of JNK, p38, and c-Jun were elevated in ATF6α knockdown cells and inhibition of JNK or p38 kinases prevented apoptosis. These results suggest that ATF6α may have a role in maintaining β-cell survival even in the absence of ER stress.
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Affiliation(s)
- Tracy Teodoro
- Division of Cellular and Molecular Biology, Toronto General Research Institute, University Health Network, Toronto, ON, Canada
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