ER Redox Homeostasis Regulates Proinsulin Trafficking and Insulin Granule Formation in the Pancreatic Islet β-Cell.

Autor:	Rohli KE; Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA.; Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA 52242, USA.; Department of Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA 52242, USA., Boyer CK; Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA.; Department of Pharmacology, University of Iowa, Iowa City, IA 52242, USA., Bearrows SC; Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA.; Department of Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA 52242, USA., Moyer MR; Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA.; Department of Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA 52242, USA., Elison WS; Department of Nutrition, Dietetics, and Food Science, Brigham Young University, Provo, UT 84602, USA., Bauchle CJ; Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA.; Department of Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA 52242, USA., Blom SE; Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA.; Department of Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA 52242, USA., Zhang J; Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48103, USA., Wang Y; Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48103, USA.; Department of Neurology, School of Medicine, University of Michigan, Ann Arbor, MI 48103, USA., Stephens SB; Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA.; Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA 52242, USA.; Department of Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA 52242, USA.
Jazyk:	angličtina
Zdroj:	Function (Oxford, England) [Function (Oxf)] 2022 Sep 28; Vol. 3 (6), pp. zqac051. Date of Electronic Publication: 2022 Sep 28 (Print Publication: 2022).
DOI:	10.1093/function/zqac051
Abstrakt:	Defects in the pancreatic β-cell's secretion system are well-described in type 2 diabetes (T2D) and include impaired proinsulin processing and a deficit in mature insulin-containing secretory granules; however, the cellular mechanisms underlying these defects remain poorly understood. To address this, we used an in situ fluorescent pulse-chase strategy to study proinsulin trafficking. We show that insulin granule formation and the appearance of nascent granules at the plasma membrane are decreased in rodent and cell culture models of prediabetes and hyperglycemia. Moreover, we link the defect in insulin granule formation to an early trafficking delay in endoplasmic reticulum (ER) export of proinsulin, which is independent of overt ER stress. Using a ratiometric redox sensor, we show that the ER becomes hyperoxidized in β-cells from a dietary model of rodent prediabetes and that addition of reducing equivalents restores ER export of proinsulin and insulin granule formation and partially restores β-cell function. Together, these data identify a critical role for the regulation of ER redox homeostasis in proinsulin trafficking and suggest that alterations in ER redox poise directly contribute to the decline in insulin granule production in T2D. This model highlights a critical link between alterations in ER redox and ER function with defects in proinsulin trafficking in T2D. Hyperoxidation of the ER lumen, shown as hydrogen peroxide, impairs proinsulin folding and disulfide bond formation that prevents efficient exit of proinsulin from the ER to the Golgi. This trafficking defect limits available proinsulin for the formation of insulin secretory granules during the development of T2D. (© The Author(s) 2022. Published by Oxford University Press on behalf of American Physiological Society.)
Databáze:	MEDLINE
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