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Lee J, Kim MJ, Moon S, Lim JY, Park KS, Jung HS. Partial Deletion of Perk Improved High-Fat Diet-Induced Glucose Intolerance in Mice. Endocrinol Metab (Seoul) 2023; 38:782-787. [PMID: 37956968 PMCID: PMC10764992 DOI: 10.3803/enm.2023.1738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/14/2023] [Accepted: 10/17/2023] [Indexed: 11/21/2023] Open
Abstract
Although pancreatic endoplasmic reticulum kinase (PERK) is indispensable to beta cells, low-dose PERK inhibitor improved glucose- stimulated insulin secretion (GSIS) and hyperglycemia in diabetic mice. Current study examined if partial deletion of Perk (Perk+/-) recapitulated the effects of PERK inhibitor, on the contrary to the complete deletion. Perk+/- mice and wild-type controls were fed with a high-fat diet (HFD) for 23 weeks. Glucose tolerance was evaluated along with serum insulin levels and islet morphology. Perk+/- mice on normal chow were comparable to wild-type mice in various metabolic features. HFD-induced obesity was not influenced by Perk reduction; however, HFD-induced glucose intolerance was significantly improved since 15-week HFD. HFD-induced compromises in GSIS were relieved by Perk reduction, accompanied by reductions in phosphorylated PERK and activating transcription factor 4 (ATF4) in the islets. Meanwhile, HFD-induced islet expansion was not significantly affected. In summary, partial deletion of Perk improved glucose tolerance and GSIS impaired by diet-induced obesity, without changes in body weights or islet mass.
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Affiliation(s)
- Jooyeop Lee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
| | - Min Joo Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
| | - Seoil Moon
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
| | - Ji Yoon Lim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
| | - Kyong Soo Park
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
| | - Hye Seung Jung
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
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2
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García-Aguilar A, Guillén C. Targeting pancreatic beta cell death in type 2 diabetes by polyphenols. Front Endocrinol (Lausanne) 2022; 13:1052317. [PMID: 36465657 PMCID: PMC9712222 DOI: 10.3389/fendo.2022.1052317] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 11/01/2022] [Indexed: 11/18/2022] Open
Abstract
Diabetes is a very complex disease which is characterized by the appearance of insulin resistance that is primarily compensated by an increase in pancreatic beta cell mass, generating hyperinsulinemia. After time, pancreatic beta cells die by apoptosis appearing in the second phase of the disease, and characterized by hypoinsulinemia. There are multiple conditions that can alter pancreatic beta cell homeostasis and viability, being the most relevant ones; ER stress, cytotoxicity by amylin, mTORC1 hyperactivity, oxidative stress, mitochondrial dysfunction, inflammation and alterations in autophagy/mitophagy flux. In addition, the possible effects that different polyphenols could exert in the modulation of these mechanisms and regulating pancreatic beta cell viability are analyzed. It is necessary a profound analysis and understanding of all the possible mechanisms involved in the control and maintenance of pancreatic beta cell viability to develop more accurate and target treatments for controlling beta cell homeostasis and preventing or even reversing type 2 diabetes mellitus.
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Affiliation(s)
- Ana García-Aguilar
- Department of Pharmacology, Pharmacognosy and Botany, Faculty of Pharmacy, Complutense University of Madrid, Madrid, Spain
- Diabetes and Associated Metabolic Diseases Networking Biomedical Research Centre Centro de Investigación Biomédica en Red. Diabetes y Enfermedades Metabólicas asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | - Carlos Guillén
- Diabetes and Associated Metabolic Diseases Networking Biomedical Research Centre Centro de Investigación Biomédica en Red. Diabetes y Enfermedades Metabólicas asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, Complutense University of Madrid, Madrid, Spain
- *Correspondence: Carlos Guillén,
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3
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Kalwat MA, Scheuner D, Rodrigues-dos-Santos K, Eizirik DL, Cobb MH. The Pancreatic ß-cell Response to Secretory Demands and Adaption to Stress. Endocrinology 2021; 162:bqab173. [PMID: 34407177 PMCID: PMC8459449 DOI: 10.1210/endocr/bqab173] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Indexed: 02/06/2023]
Abstract
Pancreatic β cells dedicate much of their protein translation capacity to producing insulin to maintain glucose homeostasis. In response to increased secretory demand, β cells can compensate by increasing insulin production capability even in the face of protracted peripheral insulin resistance. The ability to amplify insulin secretion in response to hyperglycemia is a critical facet of β-cell function, and the exact mechanisms by which this occurs have been studied for decades. To adapt to the constant and fast-changing demands for insulin production, β cells use the unfolded protein response of the endoplasmic reticulum. Failure of these compensatory mechanisms contributes to both type 1 and 2 diabetes. Additionally, studies in which β cells are "rested" by reducing endogenous insulin demand have shown promise as a therapeutic strategy that could be applied more broadly. Here, we review recent findings in β cells pertaining to the metabolic amplifying pathway, the unfolded protein response, and potential advances in therapeutics based on β-cell rest.
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Affiliation(s)
- Michael A Kalwat
- Indiana Biosciences Research Institute, Indianapolis, IN 46202, USA
| | - Donalyn Scheuner
- Indiana Biosciences Research Institute, Indianapolis, IN 46202, USA
| | | | - Decio L Eizirik
- Indiana Biosciences Research Institute, Indianapolis, IN 46202, USA
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels, Belgium
| | - Melanie H Cobb
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
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4
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Sharma RB, Landa-Galván HV, Alonso LC. Living Dangerously: Protective and Harmful ER Stress Responses in Pancreatic β-Cells. Diabetes 2021; 70:2431-2443. [PMID: 34711668 PMCID: PMC8564401 DOI: 10.2337/dbi20-0033] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Accepted: 08/03/2021] [Indexed: 01/06/2023]
Abstract
Type 2 diabetes (T2D) is a growing cause of poor health, psychosocial burden, and economic costs worldwide. The pancreatic β-cell is a cornerstone of metabolic physiology. Insulin deficiency leads to hyperglycemia, which was fatal before the availability of therapeutic insulins; even partial deficiency of insulin leads to diabetes in the context of insulin resistance. Comprising only an estimated 1 g or <1/500th of a percent of the human body mass, pancreatic β-cells of the islets of Langerhans are a vulnerable link in metabolism. Proinsulin production constitutes a major load on β-cell endoplasmic reticulum (ER), and decompensated ER stress is a cause of β-cell failure and loss in both type 1 diabetes (T1D) and T2D. The unfolded protein response (UPR), the principal ER stress response system, is critical for maintenance of β-cell health. Successful UPR guides expansion of ER protein folding capacity and increased β-cell number through survival pathways and cell replication. However, in some cases the ER stress response can cause collateral β-cell damage and may even contribute to diabetes pathogenesis. Here we review the known beneficial and harmful effects of UPR pathways in pancreatic β-cells. Improved understanding of this stress response tipping point may lead to approaches to maintain β-cell health and function.
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Affiliation(s)
- Rohit B Sharma
- Division of Endocrinology, Diabetes and Metabolism and Weill Center for Metabolic Health, Weill Cornell Medicine, New York, NY
| | - Huguet V Landa-Galván
- Division of Endocrinology, Diabetes and Metabolism and Weill Center for Metabolic Health, Weill Cornell Medicine, New York, NY
| | - Laura C Alonso
- Division of Endocrinology, Diabetes and Metabolism and Weill Center for Metabolic Health, Weill Cornell Medicine, New York, NY
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5
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Wei Q, Li H, Chen Y, Xu X, Guo G, Li X, Shen Y, Liu C, He K. Perk heterozygosity ameliorates chronic hypoxia-induced pulmonary hypertension and right ventricular hypertrophy in male rats. Clin Exp Hypertens 2021; 44:46-56. [PMID: 34648405 DOI: 10.1080/10641963.2021.1984501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
BACKGROUND Pulmonary hypertension (PH) is a rare and deadly disease characterized by remodeling of the pulmonary vasculature and increased pulmonary artery pressure. hypobaric pulmonary hypertension (HPH) is clinically classified as group 4 of pulmonary hypertension and has a poor prognosis . Previous reports showed that HPH was associated with increased endoplasmic reticulum (ER) stress. The protein kinase R-like endoplasmic reticulum kinase (PERK) is an ER-associated stress protein. However, to date, its physiological effects on HPH and RVF development remains unknown. This study aimed to assess PERK's role in HPH and RV function using in vivo experimental model. METHODS Perk-knockout male Sprague-Dawley rats were generated and were housed in either a hypobaric chamber or in a normoxic environment. After stimulation for 4 weeks, the hemodynamic parameters of the rats were measured. The heart and lungs were harvested for pathological observation. Blood was collected for the detection of inflammatory indexes. The right ventricle tissue was collected to assess phosphorylated-AKT, ROCK1, ET1, and MMP2 protein expression. RESULTS: WE FIRSTLY GENERATED PERK+/− RATS, Under normal conditions, Perk+/- rats showed no changes in mPAP(mean pulmonary artery pressure), RVHI(Right ventricular hypertrophy index), cardiomyocyte size and interstitial fibrosis, and pulmonary vascular remodeling. However, in response to chronic hypoxia, Perk+/- rats exhibited decreased in mPAP, RVHI, ventricular fibrosis, and lung remodeling compared to wild-type rats. Perk+/- rats also showed lower expression of phosphor-AKT, ROCK1, ET1, and MMP2 protein in response to chronic hypoxia. CONCLUSIONS These findings suggest that Perk heterozygosity protects against HPH and Perk may be a suitable target for treating HPH.
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Affiliation(s)
- Qingxia Wei
- Laboratory of Translational Medicine, Medical Innovation Research Division of Chinese Pla General Hospital, Beijing, China
| | - Hanlu Li
- Laboratory of Translational Medicine, Medical Innovation Research Division of Chinese Pla General Hospital, Beijing, China
| | - Yibing Chen
- Laboratory of Translational Medicine, Medical Innovation Research Division of Chinese Pla General Hospital, Beijing, China
| | - Xiang Xu
- Laboratory of Translational Medicine, Medical Innovation Research Division of Chinese Pla General Hospital, Beijing, China
| | - Ge Guo
- Laboratory of Translational Medicine, Medical Innovation Research Division of Chinese Pla General Hospital, Beijing, China
| | - Xin Li
- Laboratory of Translational Medicine, Medical Innovation Research Division of Chinese Pla General Hospital, Beijing, China.,Beijing Key Laboratory of Chronic Heart Failure Precision Medicine, Chinese Pla General Hospital, Beijing, China
| | - Yanying Shen
- Laboratory of Translational Medicine, Medical Innovation Research Division of Chinese Pla General Hospital, Beijing, China
| | - Chunlei Liu
- Laboratory of Translational Medicine, Medical Innovation Research Division of Chinese Pla General Hospital, Beijing, China.,Beijing Key Laboratory of Chronic Heart Failure Precision Medicine, Chinese Pla General Hospital, Beijing, China
| | - Kunlun He
- Laboratory of Translational Medicine, Medical Innovation Research Division of Chinese Pla General Hospital, Beijing, China.,Beijing Key Laboratory of Chronic Heart Failure Precision Medicine, Chinese Pla General Hospital, Beijing, China
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6
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Tang BM, Li ZW, Wang ZY. PERK activator CCT020312 prevents inflammation-mediated osteoporosis in the ovariectomized rats. Gynecol Endocrinol 2021; 37:342-348. [PMID: 33480297 DOI: 10.1080/09513590.2021.1874904] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
OBJECTIVE To investigate the therapeutic effects of PERK activator CCT020312 (CCT) on inflammation-mediated osteoporosis (IMO) in ovariectomized rats. METHODS Rats were divided into Sham, IMO, IMO + 1 mg/kg CCT and IMO + 2 mg/kg CCT groups. IMO models were constructed by bilateral ovariectomy (OVX) on 1st day followed by injection with magnesium silicate (Talc) on the 59th day. Sham rats did not undergo OVX surgery and were injected with saline instead of Talc. From 60th to 79th day, rats were treated with DMSO (vehicle control) in the Sham and IMO groups, and 1 or 2 mg/kg CCT020312 in treatment groups. Osteopontin (OPN), osteocalcin (OCN), tartrate-resistant acid phosphatase (TRAP), C-terminal telopeptide of type I collagen (CTX-I), and pro-inflammatory factors were measured on the 80th day. ProdigyDEXA was used to evaluate bone mineral density and content (BMD/BMC). Bone volume/total volume (BV/TV), connectivity density (Conn.D), trabecular number (Tb.N), and trabecular separation (Tb.Sp) was assessed using 3D micro-CT scanner. RESULTS CCT up-regulated Conn.D, BV/TV, and Tb.N, but down-regulated Tb.Sp in IMO rats. Besides, the declined femoral BMD and BMC in IMO rats were elevated after CCT treatment. Besides, IMO rats represented declined OPN and OCN, as well as increased TRAP, CTX-I, and pro-inflammatory factors, whereas those in the treatment groups were ameliorated regarding these indexes, with 2 mg/kg CCT showing better effect. CONCLUSION PERK activator CCT020312 can be served as a new therapeutic option for the protection against bone loss in the OVX rat model associated with inflammation probably by manipulating inflammatory factors.
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Affiliation(s)
- Bao-Ming Tang
- Department of Orthopedics, Affiliated Hospital of Qinghai University, Xining, China
| | - Zhao-Wei Li
- Department of Orthopedics, Affiliated Hospital of Qinghai University, Xining, China
| | - Zhuo-Ya Wang
- Department of Geriatrics, Affiliated Hospital of Qinghai University, Xining, China
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7
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Yashin AI, Wu D, Arbeev K, Yashkin AP, Akushevich I, Bagley O, Duan M, Ukraintseva S. Roles of interacting stress-related genes in lifespan regulation: insights for translating experimental findings to humans. JOURNAL OF TRANSLATIONAL GENETICS AND GENOMICS 2021; 5:357-379. [PMID: 34825130 PMCID: PMC8612394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
AIM Experimental studies provided numerous evidence that caloric/dietary restriction may improve health and increase the lifespan of laboratory animals, and that the interplay among molecules that sense cellular stress signals and those regulating cell survival can play a crucial role in cell response to nutritional stressors. However, it is unclear whether the interplay among corresponding genes also plays a role in human health and lifespan. METHODS Literature about roles of cellular stressors have been reviewed, such as amino acid deprivation, and the integrated stress response (ISR) pathway in health and aging. Single nucleotide polymorphisms (SNPs) in two candidate genes (GCN2/EIF2AK4 and CHOP/DDIT3) that are closely involved in the cellular stress response to amino acid starvation, have been selected using information from experimental studies. Associations of these SNPs and their interactions with human survival in the Health and Retirement Study data have been estimated. The impact of collective associations of multiple interacting SNP pairs on survival has been evaluated, using a recently developed composite index: the SNP-specific Interaction Polygenic Risk Score (SIPRS). RESULTS Significant interactions have been found between SNPs from GCN2/EIF2AK4 and CHOP/DDI3T genes that were associated with survival 85+ compared to survival between ages 75 and 85 in the total sample (males and females combined) and in females only. This may reflect sex differences in genetic regulation of the human lifespan. Highly statistically significant associations of SIPRS [constructed for the rs16970024 (GCN2/EIF2AK4) and rs697221 (CHOP/DDIT3)] with survival in both sexes also been found in this study. CONCLUSION Identifying associations of the genetic interactions with human survival is an important step in translating the knowledge from experimental to human aging research. Significant associations of multiple SNPxSNP interactions in ISR genes with survival to the oldest old age that have been found in this study, can help uncover mechanisms of multifactorial regulation of human lifespan and its heterogeneity.
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8
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Jiang M, Kuang Z, He Y, Cao Y, Yu T, Cheng J, Liu W, Wang W. SNAPIN Regulates Cell Cycle Progression to Promote Pancreatic β Cell Growth. Front Endocrinol (Lausanne) 2021; 12:624309. [PMID: 34194388 PMCID: PMC8237857 DOI: 10.3389/fendo.2021.624309] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 05/13/2021] [Indexed: 02/05/2023] Open
Abstract
In diabetes mellitus, death of β cell in the pancreas occurs throughout the development of the disease, with loss of insulin production. The maintenance of β cell number is essential to maintaining normoglycemia. SNAPIN has been found to regulate insulin secretion, but whether it induces β cell proliferation remains to be elucidated. This study aimed to explore the physiological roles of SNAPIN in β cell proliferation. SNAPIN expression increases with the age of mice and SNAPIN is down-regulated in diabetes. KEGG pathway and GO analysis showed that SNAPIN- interacting proteins were enriched in cell cycle regulation. B cell cycle was arrested in the S phase, and cell proliferation was inhibited after SNAPIN knockdown. The expression of CDK2, CDK4 and CCND1 proteins in the S phase of the cell cycle were reduced after SNAPIN knockdown, whereas they were increased after overexpression of SNAPIN. In addition, insulin protein and mRNA levels also increased or decreased after SNAPIN knockdown or overexpression, respectively. Conclusions: Our data indicate that SNAPIN mediates β cells proliferation and insulin secretion, and provide evidences that SNAPIN might be a pharmacotherapeutic target for diabetes mellitus.
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Affiliation(s)
- Mengxue Jiang
- Department of Endocrinology, Xiang’an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Zhijian Kuang
- Fujian Provincial KeyLaboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Yaohui He
- Fujian Provincial KeyLaboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Yin Cao
- Fujian Provincial KeyLaboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Tingyan Yu
- Department of Endocrinology, Xiang’an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Jidong Cheng
- Department of Endocrinology, Xiang’an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
- *Correspondence: Jidong Cheng, ; Wen Liu, ; Wei Wang,
| | - Wen Liu
- Fujian Provincial KeyLaboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
- *Correspondence: Jidong Cheng, ; Wen Liu, ; Wei Wang,
| | - Wei Wang
- Department of Endocrinology, Xiang’an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
- *Correspondence: Jidong Cheng, ; Wen Liu, ; Wei Wang,
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9
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Sharma RB, Darko C, Alonso LC. Intersection of the ATF6 and XBP1 ER stress pathways in mouse islet cells. J Biol Chem 2020; 295:14164-14177. [PMID: 32788214 DOI: 10.1074/jbc.ra120.014173] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 08/06/2020] [Indexed: 12/20/2022] Open
Abstract
Success or failure of pancreatic beta cell adaptation to ER stress is a determinant of diabetes susceptibility. The ATF6 and IRE1/XBP1 pathways are separate ER stress-response effectors important to beta cell health and function. ATF6α. and XBP1 direct overlapping transcriptional responses in some cell types. However, the signaling dynamics and interdependence of ATF6α and XBP1 in pancreatic beta cells have not been explored. To assess pathway-specific signal onset, we performed timed exposures of primary mouse islet cells to ER stressors and measured the early transcriptional response. Comparing the time course of induction of ATF6 and XBP1 targets suggested that the two pathways have similar response dynamics. The role of ATF6α in target induction was assessed by acute knockdown using islet cells from Atf6α flox/flox mice transduced with adenovirus expressing Cre recombinase. Surprisingly, given the mild impact of chronic deletion in mice, acute ATF6α knockdown markedly reduced ATF6-pathway target gene expression under both basal and stressed conditions. Intriguingly, although ATF6α knockdown did not alter Xbp1 splicing dynamics or intensity, it did reduce induction of XBP1 targets. Inhibition of Xbp1 splicing did not decrease induction of ATF6α targets. Taken together, these data suggest that the XBP1 and ATF6 pathways are simultaneously activated in islet cells in response to acute stress and that ATF6α is required for full activation of XBP1 targets, but XBP1 is not required for activation of ATF6α targets. These observations improve understanding of the ER stress transcriptional response in pancreatic islets.
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Affiliation(s)
- Rohit B Sharma
- Division of Endocrinology, Diabetes and Metabolism, Weill Cornell Medicine, New York, New York, USA .,Weill Center for Metabolic Health, Weill Cornell Medicine, New York, New York, USA
| | - Christine Darko
- Division of Endocrinology, Diabetes and Metabolism, Weill Cornell Medicine, New York, New York, USA.,Weill Center for Metabolic Health, Weill Cornell Medicine, New York, New York, USA
| | - Laura C Alonso
- Division of Endocrinology, Diabetes and Metabolism, Weill Cornell Medicine, New York, New York, USA .,Weill Center for Metabolic Health, Weill Cornell Medicine, New York, New York, USA
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10
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Lenghel A, Gheorghita AM, Vacaru AM, Vacaru AM. What Is the Sweetest UPR Flavor for the β-cell? That Is the Question. Front Endocrinol (Lausanne) 2020; 11:614123. [PMID: 33613449 PMCID: PMC7891099 DOI: 10.3389/fendo.2020.614123] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 11/24/2020] [Indexed: 01/01/2023] Open
Abstract
Unfolded protein response (UPR) is a process conserved from yeasts to mammals and, based on the generally accepted dogma, helps the secretory performance of a cell, by improving its capacity to cope with a burden in the endoplasmic reticulum (ER). The ER of β-cells, "professional secretory cells", has to manage tremendous amounts of insulin, which elicits a strong pressure on the ER intrinsic folding capacity. Thus, the constant demand for insulin production results in misfolded proinsulin, triggering a physiological upregulation of UPR to restore homeostasis. Most diabetic disorders are characterized by the loss of functional β-cells, and the pathological side of UPR plays an instrumental role. The transition from a homeostatic to a pathological UPR that ultimately leads to insulin-producing β-cell decay entails complex cellular processes and molecular mechanisms which remain poorly described so far. Here, we summarize important processes that are coupled with or driven by UPR in β-cells, such as proliferation, inflammation and dedifferentiation. We conclude that the UPR comes in different "flavors" and each of them is correlated with a specific outcome for the cell, for survival, differentiation, proliferation as well as cell death. All these greatly depend on the way UPR is triggered, however what exactly is the switch that favors the activation of one UPR as opposed to others is largely unknown. Substantial work needs to be done to progress the knowledge in this important emerging field as this will help in the development of novel and more efficient therapies for diabetes.
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11
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Zheng Z, Shang Y, Tao J, Zhang J, Sha B. Endoplasmic Reticulum Stress Signaling Pathways: Activation and Diseases. Curr Protein Pept Sci 2019; 20:935-943. [PMID: 31223084 DOI: 10.2174/1389203720666190621103145] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 05/31/2019] [Accepted: 06/03/2019] [Indexed: 02/06/2023]
Abstract
Secretory and membrane proteins are folded in the endoplasmic reticulum (ER) prior to their exit. When ER function is disturbed by exogenous and endogenous factors, such as heat shock, ultraviolet radiation, hypoxia, or hypoglycemia, the misfolded proteins may accumulate, promoting ER stress. To rescue this unfavorable situation, the unfolded protein response is activated to reduce misfolded proteins within the ER. Upon ER stress, the ER transmembrane sensor molecules inositol-requiring enzyme 1 (IRE1), RNA-dependent protein kinase (PKR)-like ER kinase (PERK), and activating transcription factor 6, are activated. Here, we discuss the mechanisms of PERK and IRE1 activation and describe two working models for ER stress initiation: the BiP-dependent model and the ligand-driven model. ER stress activation has been linked to multiple diseases, including cancers, Alzheimer's disease, and diabetes. Thus, the regulation of ER stress may provide potential therapeutic targets for these diseases.
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Affiliation(s)
- Zhi Zheng
- Department of Cell, Developmental and Integrative Biology (CDIB), University of Alabama at Birmingham, Birmingham, AL 35294, United States.,Department of General Surgery, Beijing Friendship Hospital, Capital Medical University, 95 Yong-an Road, Xi-Cheng District, Beijing 100050, China
| | - Yuxi Shang
- Department of Hematology, Fuxing Hospital, Eighth Clinical Medical College, Capital Medical University, Beijing 100038, China
| | - Jiahui Tao
- Department of Cell, Developmental and Integrative Biology (CDIB), University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Jun Zhang
- Department of General Surgery, Beijing Friendship Hospital, Capital Medical University, 95 Yong-an Road, Xi-Cheng District, Beijing 100050, China
| | - Bingdong Sha
- Department of Cell, Developmental and Integrative Biology (CDIB), University of Alabama at Birmingham, Birmingham, AL 35294, United States
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12
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Feng M, Crowley NA, Patel A, Guo Y, Bugni SE, Luscher B. Reversal of a Treatment-Resistant, Depression-Related Brain State with the Kv7 Channel Opener Retigabine. Neuroscience 2019; 406:109-125. [PMID: 30858110 DOI: 10.1016/j.neuroscience.2019.03.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 02/28/2019] [Accepted: 03/01/2019] [Indexed: 12/27/2022]
Abstract
Neuroinflammation is associated with increased vulnerability to diverse psychiatric conditions, including treatment-resistant major depressive disorder (MDD). Here we assessed whether high fat diet (HFD) induced neuroinflammation may be suitable to model a treatment-resistant depressive-like brain state in mice. Male and female mice were fed a HFD for 18 weeks, followed by quantitation of glucose tolerance, inflammatory markers of brain tissue (TNFα, IL-6, IL-1β, Iba-1), neural excitability in the prelimbic cortex (PLC), as well as assessment of emotional reactivity and hedonic behavior in a battery of behavioral tests. In addition, we assessed the behavioral responsiveness of mice to fluoxetine, desipramine, ketamine, and the Kv7 channel opener and anticonvulsant retigabine. HFD exposure led to glucose intolerance and neuroinflammation in male mice, with similar but non-significant trends in females. Neuroinflammation of males was associated with anxious-depressive-like behavior and defects in working memory, along with neural hyperexcitability and increased Ih currents of pyramidal cells in the PLC. The behavioral changes were largely resistant to chronic treatment with fluoxetine and desipramine, as well as ketamine. By contrast, retigabine (also known as ezogabine) normalized neural excitability and Ih currents recorded from slices of HFD-treated animals and significantly ameliorated most of the behavioral impairments, without effects in control diet exposed animals. Thus, treatment resistant depressive-like brain states that are associated with chronic neuroinflammation may involve hyperexcitability of pyramidal neurons and may be effectively treated by retigabine.
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Affiliation(s)
- Mengyang Feng
- Department of Biology, Pennsylvania State University, University Park, PA 16802; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802
| | - Nicole A Crowley
- Department of Biology, Pennsylvania State University, University Park, PA 16802; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802
| | - Akshilkumar Patel
- Department of Biology, Pennsylvania State University, University Park, PA 16802; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802
| | - Yao Guo
- Department of Biology, Pennsylvania State University, University Park, PA 16802; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802
| | - Sierra E Bugni
- Department of Biology, Pennsylvania State University, University Park, PA 16802; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802
| | - Bernhard Luscher
- Department of Biology, Pennsylvania State University, University Park, PA 16802; Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, PA 16802; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802.
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13
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Hurst KE, Lawrence KA, Essman MT, Walton ZJ, Leddy LR, Thaxton JE. Endoplasmic Reticulum Stress Contributes to Mitochondrial Exhaustion of CD8 + T Cells. Cancer Immunol Res 2019; 7:476-486. [PMID: 30659052 DOI: 10.1158/2326-6066.cir-18-0182] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 09/23/2018] [Accepted: 12/12/2018] [Indexed: 12/24/2022]
Abstract
Tumor antigen-specific T cells rapidly lose energy and effector function in tumors. The cellular mechanisms by which energy loss and inhibition of effector function occur in tumor-infiltrating lymphocytes (TILs) are ill-defined, and methods to identify tumor antigen-specific TILs that experience such stress are unknown. Processes upstream of the mitochondria guide cell-intrinsic energy depletion. We hypothesized that a mechanism of T-cell-intrinsic energy consumption was the process of oxidative protein folding and disulfide bond formation that takes place in the endoplasmic reticulum (ER) guided by protein kinase R-like endoplasmic reticulum kinase (PERK) and downstream PERK axis target ER oxidoreductase 1 (ERO1α). To test this hypothesis, we created TCR transgenic mice with a T-cell-specific PERK gene deletion (OT1 + Lckcre+ PERK f/f , PERK KO). We found that PERK KO and T cells that were pharmacologically inhibited by PERK or ERO1α maintained reserve energy and exhibited a protein profile consistent with reduced oxidative stress. These T-cell groups displayed superior tumor control compared with T effectors. We identified a biomarker of ER-induced mitochondrial exhaustion in T cells as mitochondrial reactive oxygen species (mtROS), and found that PD-1+ tumor antigen-specific CD8+ TILs express mtROS. In vivo treatment with a PERK inhibitor abrogated mtROS in PD-1+ CD8+ TILs and bolstered CD8+ TIL viability. Combination therapy enabled 100% survival and 71% tumor clearance in a sarcoma mouse model. Our data identify the ER as a regulator of T-cell energetics and indicate that ER elements are effective targets to improve cancer immunotherapy.
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Affiliation(s)
- Katie E Hurst
- Department of Orthopedics, College of Medicine, Medical University of South Carolina Medical School, Charleston, South Carolina
| | - Kiley A Lawrence
- Department of Orthopedics, College of Medicine, Medical University of South Carolina Medical School, Charleston, South Carolina
| | - Matthew T Essman
- Department of Orthopedics, College of Medicine, Medical University of South Carolina Medical School, Charleston, South Carolina.,Medical University of South Carolina Medical School, Charleston, South Carolina
| | - Zeke J Walton
- Department of Orthopedics, College of Medicine, Medical University of South Carolina Medical School, Charleston, South Carolina.,Hollings Cancer Center, Medical University of South Carolina Medical School, Charleston, South Carolina
| | - Lee R Leddy
- Department of Orthopedics, College of Medicine, Medical University of South Carolina Medical School, Charleston, South Carolina.,Hollings Cancer Center, Medical University of South Carolina Medical School, Charleston, South Carolina
| | - Jessica E Thaxton
- Department of Orthopedics, College of Medicine, Medical University of South Carolina Medical School, Charleston, South Carolina. .,Hollings Cancer Center, Medical University of South Carolina Medical School, Charleston, South Carolina.,Department of Microbiology and Immunology, Medical University of South Carolina Medical School, Charleston, South Carolina
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14
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Kefalas G, Jouvet N, Baldwin C, Estall JL, Larose L. Peptide-based sequestration of the adaptor protein Nck1 in pancreatic β cells enhances insulin biogenesis and protects against diabetogenic stresses. J Biol Chem 2018; 293:12516-12524. [PMID: 29941454 DOI: 10.1074/jbc.ra118.002728] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Revised: 06/16/2018] [Indexed: 01/14/2023] Open
Abstract
One feature of diabetes is the failure of pancreatic β cells to produce insulin, but the molecular mechanisms leading to this failure remain unclear. Increasing evidence supports a role for protein kinase R-like endoplasmic reticulum kinase (PERK) in the development and function of healthy pancreatic β cells. Previously, our group identified the adaptor protein Nck1 as a negative regulator of PERK. Indeed, we demonstrated that Nck1, by directly binding PERK autophosphorylated on Tyr561, limits PERK activation and signaling. Accordingly, we found that stable depletion of Nck1 in β cells promotes PERK activation and signaling, increases insulin biosynthesis, and improves cell viability in response to diabetes-related stresses. Herein, we explored the therapeutic potential of abrogating the interaction between Nck and PERK to improve β-cell function and survival. To do so, we designed and used a peptide containing the minimal PERK sequence involved in binding Nck1 conjugated to the cell-permeable protein transduction domain from the HIV protein TAT. In the current study, we confirm that the synthetic TAT-Tyr(P)561 phosphopeptide specifically binds the SH2 domain of Nck and prevents Nck interaction with PERK, thereby promoting basal PERK activation. Moreover, we report that treatment of β cells with TAT-Tyr(P)561 inhibits glucolipotoxicity-induced apoptosis, whereas it enhances insulin production and secretion. Taken together, our results support the potential of sequestering Nck using a synthetic peptide to enhance basal PERK activation and create more robust β cells.
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Affiliation(s)
- George Kefalas
- From the Research Institute of the McGill University Health Centre, Montreal, Quebec H4A 3J1, Canada.,the Division of Experimental Medicine, Department of Medicine, McGill University, Montreal, Quebec H4A 3J1, Canada, and
| | - Nathalie Jouvet
- the Institut de Recherches Cliniques de Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Cindy Baldwin
- From the Research Institute of the McGill University Health Centre, Montreal, Quebec H4A 3J1, Canada.,the Institut de Recherches Cliniques de Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Jennifer L Estall
- the Division of Experimental Medicine, Department of Medicine, McGill University, Montreal, Quebec H4A 3J1, Canada, and .,the Institut de Recherches Cliniques de Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Louise Larose
- From the Research Institute of the McGill University Health Centre, Montreal, Quebec H4A 3J1, Canada, .,the Division of Experimental Medicine, Department of Medicine, McGill University, Montreal, Quebec H4A 3J1, Canada, and
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15
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Kim MJ, Min SH, Shin SY, Kim MN, Lee H, Jang JY, Kim SW, Park KS, Jung HS. Attenuation of PERK enhances glucose-stimulated insulin secretion in islets. J Endocrinol 2018; 236:125-136. [PMID: 29273589 DOI: 10.1530/joe-17-0497] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 12/22/2017] [Indexed: 01/18/2023]
Abstract
PERK is a pancreatic endoplasmic reticulum (ER) kinase. Its complete deletion in pancreatic β cells induces insulin deficiency; however, the effects of partial Perk suppression are unclear. We investigated the effect of partial PERK suppression using the specific PERK inhibitors GSK2606414 and GSK2656157. Low-dose GSK2606414 treatment for 24 h enhanced glucose-stimulated insulin secretion (GSIS), islet insulin content and calcium transit in mouse (at 40 nM) and human (at 50-100 nM) pancreatic islets. GSK2606414 also induced the expression of the ER chaperone BiP and the release of calcium from the ER. When Bip expression was inhibited using a Bip siRNA, the GSK2606414-induced augmentation of the ER calcium level, islet insulin contents, glucose-stimulated cytosolic calcium transit and GSIS were abrogated. In both wild-type and insulin-deficient Atg7-knockout mice, 8 weeks of GSK2656157 treatment enhanced GSIS and improved hyperglycemia without affecting body weight. In conclusion, partial PERK inhibition induced BiP expression in islets, increased glucose-stimulated calcium transit and islet insulin contents and enhanced GSIS, suggesting that low-dose PERK inhibitors could potentially be used to treat insulin deficiency.
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Affiliation(s)
- Min Joo Kim
- Department of Internal MedicineSeoul National University College of Medicine, Seoul, Republic of Korea
| | - Se Hee Min
- Department of Internal MedicineSeoul National University College of Medicine, Seoul, Republic of Korea
| | - Seon Young Shin
- Innovative Research Institute for Cell TherapySeoul, Republic of Korea
| | - Mi Na Kim
- Innovative Research Institute for Cell TherapySeoul, Republic of Korea
| | - Hakmo Lee
- Innovative Research Institute for Cell TherapySeoul, Republic of Korea
| | - Jin Young Jang
- Department of SurgerySeoul National University College of Medicine, Seoul, Republic of Korea
| | - Sun-Whe Kim
- Department of SurgerySeoul National University College of Medicine, Seoul, Republic of Korea
| | - Kyong Soo Park
- Department of Internal MedicineSeoul National University College of Medicine, Seoul, Republic of Korea
- Innovative Research Institute for Cell TherapySeoul, Republic of Korea
| | - Hye Seung Jung
- Department of Internal MedicineSeoul National University College of Medicine, Seoul, Republic of Korea
- Innovative Research Institute for Cell TherapySeoul, Republic of Korea
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16
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Local Inhibition of PERK Enhances Memory and Reverses Age-Related Deterioration of Cognitive and Neuronal Properties. J Neurosci 2017; 38:648-658. [PMID: 29196323 DOI: 10.1523/jneurosci.0628-17.2017] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 10/25/2017] [Accepted: 11/10/2017] [Indexed: 01/08/2023] Open
Abstract
Protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK) is one of four known kinases that respond to cellular stress by deactivating the eukaryotic initiation factor 2 α (eIF2α) or other signal transduction cascades. Recently, both eIF2α and its kinases were found to play a role in normal and pathological brain function. Here, we show that reduction of either the amount or the activity of PERK, specifically in the CA1 region of the hippocampus in young adult male mice, enhances neuronal excitability and improves cognitive function. In addition, this manipulation rescues the age-dependent cellular phenotype of reduced excitability and memory decline. Specifically, the reduction of PERK expression in the CA1 region of the hippocampus of middle-aged male mice using a viral vector rejuvenates hippocampal function and improves hippocampal-dependent learning. These results delineate a mechanism for behavior and neuronal aging and position PERK as a promising therapeutic target for age-dependent brain malfunction.SIGNIFICANCE STATEMENT We found that local reduced protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK) expression or activity in the hippocampus enhances neuronal excitability and cognitive function in young normal mice, that old CA1 pyramidal cells have reduced excitability and increased PERK expression that can be rescued by reducing PERK expression in the hippocampus, and that reducing PERK expression in the hippocampus of middle-aged mice enhances hippocampal-dependent learning and memory and restores it to normal performance levels of young mice. These findings uncover an entirely new biological link among PERK, neuronal intrinsic properties, aging, and cognitive function. Moreover, our findings propose a new way to fight mild cognitive impairment and aging-related cognitive deterioration.
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17
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Soeda J, Mouralidarane A, Cordero P, Li J, Nguyen V, Carter R, Kapur SR, Pombo J, Poston L, Taylor PD, Vinciguerra M, Oben JA. Maternal obesity alters endoplasmic reticulum homeostasis in offspring pancreas. J Physiol Biochem 2016; 72:281-91. [PMID: 26979740 PMCID: PMC4873529 DOI: 10.1007/s13105-016-0476-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 02/29/2016] [Indexed: 12/11/2022]
Abstract
The prevalence of non-alcoholic fatty pancreas disease (NAFPD) is increasing in parallel with obesity rates. Stress-related alterations in endoplasmic reticulum (ER), such as the unfolded protein response (UPR), are associated with obesity. The aim of this study was to investigate ER imbalance in the pancreas of a mice model of adult and perinatal diet-induced obesity. Twenty female C57BL/6J mice were assigned to control (Con) or obesogenic (Ob) diets prior to and during pregnancy and lactation. Their offspring were weaned onto Con or Ob diets up to 6 months post-partum. Then, after sacrifice, plasma biochemical analyses, gene expression, and protein concentrations were measured in pancreata. Offspring of Ob-fed mice had significantly increased body weight (p < 0.001) and plasma leptin (p < 0.001) and decreased insulin (p < 0.01) levels. Maternal obesogenic diet decreased the total and phosphorylated Eif2α and increased spliced X-box binding protein 1 (XBP1). Pancreatic gene expression of downstream regulators of UPR (EDEM, homocysteine-responsive endoplasmic reticulum-resident (HERP), activating transcription factor 4 (ATF4), and C/EBP homologous protein (CHOP)) and autophagy-related proteins (LC3BI/LC3BII) were differently disrupted by obesogenic feeding in both mothers and offspring (from p < 0.1 to p < 0.001). Maternal obesity and Ob feeding in their offspring alter UPR in NAFPD, with involvement of proapoptotic and autophagy-related markers. Upstream and downstream regulators of PERK, IRE1α, and ATF6 pathways were affected differently following the obesogenic insults.
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Affiliation(s)
- Jumpei Soeda
- Institute for Liver and Digestive Health, University College London, London, UK
| | | | - Paul Cordero
- Institute for Liver and Digestive Health, University College London, London, UK
| | - Jiawei Li
- Institute for Liver and Digestive Health, University College London, London, UK
| | - Vi Nguyen
- Institute for Liver and Digestive Health, University College London, London, UK
| | - Rebeca Carter
- Institute for Liver and Digestive Health, University College London, London, UK
| | - Sabrina R Kapur
- Institute for Liver and Digestive Health, University College London, London, UK
| | - Joaquim Pombo
- Division of Women's Health, King's College London, London, UK
| | - Lucilla Poston
- Division of Women's Health, King's College London, London, UK
| | - Paul D Taylor
- Division of Women's Health, King's College London, London, UK
| | - Manlio Vinciguerra
- Institute for Liver and Digestive Health, University College London, London, UK.
- International Clinical Research Center (ICRC), Center for Translational Medicine (CTM), St. Anne's University Hospital, Brno, Czech Republic.
- Centro Studi Fegato (CSF)-Liver Research Center, Fondazione Italiana Fegato, Trieste, Italy.
| | - Jude A Oben
- Institute for Liver and Digestive Health, University College London, London, UK.
- Department of Gastroenterology and Hepatology, Guy's and St Thomas' Hospital, NHS Foundation Trust, London, UK.
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18
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Sharma RB, O'Donnell AC, Stamateris RE, Ha B, McCloskey KM, Reynolds PR, Arvan P, Alonso LC. Insulin demand regulates β cell number via the unfolded protein response. J Clin Invest 2015; 125:3831-46. [PMID: 26389675 DOI: 10.1172/jci79264] [Citation(s) in RCA: 155] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 08/13/2015] [Indexed: 12/11/2022] Open
Abstract
Although stem cell populations mediate regeneration of rapid turnover tissues, such as skin, blood, and gut, a stem cell reservoir has not been identified for some slower turnover tissues, such as the pancreatic islet. Despite lacking identifiable stem cells, murine pancreatic β cell number expands in response to an increase in insulin demand. Lineage tracing shows that new β cells are generated from proliferation of mature, differentiated β cells; however, the mechanism by which these mature cells sense systemic insulin demand and initiate a proliferative response remains unknown. Here, we identified the β cell unfolded protein response (UPR), which senses insulin production, as a regulator of β cell proliferation. Using genetic and physiologic models, we determined that among the population of β cells, those with an active UPR are more likely to proliferate. Moreover, subthreshold endoplasmic reticulum stress (ER stress) drove insulin demand-induced β cell proliferation, through activation of ATF6. We also confirmed that the UPR regulates proliferation of human β cells, suggesting that therapeutic UPR modulation has potential to expand β cell mass in people at risk for diabetes. Together, this work defines a stem cell-independent model of tissue homeostasis, in which differentiated secretory cells use the UPR sensor to adapt organ size to meet demand.
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