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Control of beta cell function and survival by RYR2-mediated calcium signals

通过 RYR2 介导的钙信号控制 β 细胞功能和存活

基本信息

批准号：
10491304
负责人：
Carmella Evans-Molina
金额：
$ 45.3万
依托单位：
INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-09-20 至 2026-08-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10491304
关键词：
Address Age Alleles Apoptosis Beta Cell Biophysics Bolus Infusion Ca(2+)-Transporting ATPase Calcium Calcium Signaling Cell Death Cell Survival Cell membrane Cell physiology Cells Cellular biology Closure by clamp Complex Data Data Science Detection Diabetes Mellitus Disease model Electrophysiology (science)Endoplasmic Reticulum Equilibrium Event Failure Functional disorder Genes Genetic Glucose Glucose Intolerance Health Human ITPR1 gene Image In Vitro Individual Inflammatory Inositol Insulin Insulin-Dependent Diabetes Mellitus Ion Channel Knock-out Knockout Mice Knowledge Link Maintenance Mass Spectrum Analysis Measures Mediating Membrane Membrane Potentials Messenger RNA Metabolic Metabolic stress Modeling Molecular Monitor Morphology Mus Non-Insulin-Dependent Diabetes Mellitus Organelles Pancreas Pattern Pharmacology Physics Physiological Physiology Play Process Production Protein Isoforms Proteins Proteomics Publishing Pump Quantitative Reverse Transcriptase PCR Rattus Reagent Regulation Research Role RyR2 Ryanodine Receptor Calcium Release Channel Ryanodine Receptors Shapes Signal Transduction Slice Stress Structure of beta Cell of islet Testing Tissues Work base blood glucose regulation diet-induced obesity endoplasmic reticulum stress experimental study glucose tolerance humoral immunity deficiency imaging approach imaging modality impaired glucose tolerance in vivo insulin regulation insulin secretion intravital imaging intravital microscopy islet light microscopy mitochondrial metabolism mouse model multidisciplinary novel quantitative imaging receptor response temporal measurement tool tripolyphosphate two-photon uptake voltage voltage clamp

项目摘要

PROJECT SUMMARY/ABSTRACT Despite the importance of β cell failure in the progression of diabetes (type 1, type 2, and multiple monogenic forms), the underlying molecular mechanisms responsible for β cell dysfunction remain incompletely understood. Release of insulin from the pancreatic β cell occurs in response to dynamic changes in cytosolic calcium (Ca2+) levels. To date, the majority of studies of β cell physiology have focused on the regulation of Ca2+ influx via plasma membrane ion channels, which have traditionally been more amenable to study via electrophysiological approaches. These studies have supported a dominant role for KATP channel-dependent plasma membrane depolarization and Ca2+ influx via voltage-gated Ca2+ channels in the regulation of insulin release, especially in response to very high concentrations of glucose. However, recent improvements in high temporal resolution imaging pioneered by our group have enabled the detection of robust Ca2+ signals in β cells stimulated with more physiologically relevant glucose concentrations, even in the absence of changes in plasma membrane potential, pointing to a critical role for the regulated release of Ca2+ from intracellular stores. In support of this, our published and preliminary data show that pharmacological manipulation of the activity of intracellular ryanodine receptors (RYR) uniquely modulates these ultrafast Ca2+ release events, even in voltage-clamp conditions, while also impacting glucose-stimulated insulin secretion. Together with other groups, we have found that the RYR2 isoform predominates in pancreatic β cells, and importantly showed using qRT-PCR and mass spectometry-based proteomics that RYR2 mRNA and protein can be identified in human and mouse islets and purified β cells. Furthermore, our preliminary data indicate that mice with β cell selective Ryr2 knockout have reduced insulin secretion and glucose intolerance, while ex vivo studies suggest that ER Ca2+ leak via dysregulated RYR activity leads to alterations in β cell Ca2+ signalling and accelerated β cell death. Against this background, we hypothesize that RYR2 channels serve as critical rheostats of β cell health and function and that they play key roles in diabetes progression. To test this hypothesis, we have assembled a multidisciplinary MPI team with expertise in β cell biology, diabetes physiology, quantitative imaging, and disease modelling, and three specific aims are proposed. In Specific Aim 1, we will quantify β cell RYR2 activity and roles in pancreatic slices and in vivo using intravital imaging. Specific Aim 2 will determine the in vivo role of β cell RYR2 in insulin secretion, β cell survival, and glucose homeostasis using a highly β cell-specific knockout mouse model. Specific Aim 3 will utilize mass spectrometry to determine mechanisms underlying ER stress-induced RYR2 dysfunction and in vitro and in vivo mouse models to define how ER stress-induced RYR2 dysfunction impacts β cell Ca2+ signaling and survival.

项目总结/文摘