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Yamamoto WR, Bone RN, Sohn P, Syed F, Reissaus CA, Mosley AL, Wijeratne AB, True JD, Tong X, Kono T, Evans-Molina C. Endoplasmic reticulum stress alters ryanodine receptor function in the murine pancreatic β cell. J Biol Chem 2018; 294:168-181. [PMID: 30420428 DOI: 10.1074/jbc.ra118.005683] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Revised: 11/08/2018] [Indexed: 01/23/2023] Open
Abstract
Alterations in endoplasmic reticulum (ER) calcium (Ca2+) levels diminish insulin secretion and reduce β-cell survival in both major forms of diabetes. The mechanisms responsible for ER Ca2+ loss in β cells remain incompletely understood. Moreover, a specific role for either ryanodine receptor (RyR) or inositol 1,4,5-triphosphate receptor (IP3R) dysfunction in the pathophysiology of diabetes remains largely untested. To this end, here we applied intracellular and ER Ca2+ imaging techniques in INS-1 β cells and isolated islets to determine whether diabetogenic stressors alter RyR or IP3R function. Our results revealed that the RyR is sensitive mainly to ER stress-induced dysfunction, whereas cytokine stress specifically alters IP3R activity. Consistent with this observation, pharmacological inhibition of the RyR with ryanodine and inhibition of the IP3R with xestospongin C prevented ER Ca2+ loss under ER and cytokine stress conditions, respectively. However, RyR blockade distinctly prevented β-cell death, propagation of the unfolded protein response (UPR), and dysfunctional glucose-induced Ca2+ oscillations in tunicamycin-treated INS-1 β cells and mouse islets and Akita islets. Monitoring at the single-cell level revealed that ER stress acutely increases the frequency of intracellular Ca2+ transients that depend on both ER Ca2+ leakage from the RyR and plasma membrane depolarization. Collectively, these findings indicate that RyR dysfunction shapes ER Ca2+ dynamics in β cells and regulates both UPR activation and cell death, suggesting that RyR-mediated loss of ER Ca2+ may be an early pathogenic event in diabetes.
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Affiliation(s)
- Wataru R Yamamoto
- Departments of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Robert N Bone
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Paul Sohn
- Departments of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Farooq Syed
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Christopher A Reissaus
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Amber L Mosley
- Departments of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Aruna B Wijeratne
- Departments of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Jason D True
- Departments of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Xin Tong
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37235
| | - Tatsuyoshi Kono
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Carmella Evans-Molina
- Departments of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202; Departments of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202; Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana 46202; Roudebush Veterans Affairs Medical Center, Indianapolis, Indiana 46202.
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