The Role of Pancreatic β-cell Store-Operated Calcium Entry in Fatty Acid Metabolism

胰腺β细胞库操作的钙进入在脂肪酸代谢中的作用

基本信息

批准号：
9910840
负责人：
Paul Sohn
金额：
$ 2.9万
依托单位：
TRUSTEES OF INDIANA UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-09-09 至 2023-09-08
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9910840
关键词：
Ablation Address Adverse effects Affect Award Beta Cell Calcium Calpain Caring Caspase Cations Cell Death Cell Survival Cell physiology Cells Chronic Clinical Complex Coupled Cyclic AMP Data Development Diabetes Mellitus Diet Endoplasmic Reticulum Ensure Extracellular Space Fasting Fat-Restricted Diet Fatty Acids Fatty acid glycerol esters Fellowship Functional disorder Genetic Glucose Glucose Intolerance Glucose tolerance test Goals High Fat Diet Homeostasis Hyperglycemia Immunohistochemistry Impairment Indiana Individual Injections Insulin Insulin Resistance Intracellular Accumulation of Lipids Knock-out Knockout Mice Lead Link Lipids Lipolysis Maintenance Measures Mediating Medical Mentorship Metabolic Diseases Mitochondria Modeling Molecular Morphology Mus Non-Insulin-Dependent Diabetes Mellitus Nonesterified Fatty Acids Obesity Oleates Oleic Acids Palmitates Pathogenesis Pathway interactions Pattern Peripheral Physiological Play Predisposition Prevalence Production Protein Isoforms Research Project Grants Research Training Resistance development Role STIM1 gene Scientist Secretory Cell Serum Signal Transduction Stress Structure of beta Cell of islet Syndrome Testing Training Training Programs Universities Work base blood glucose regulation collaborative environment cost diabetes management diabetic endoplasmic reticulum stress euglycemia experimental study fatty acid metabolism fatty acid oxidation feeding glucose metabolism histological stains immunocytochemistry in vivo insight insulin secretion insulin sensitivity insulin tolerance islet lipid metabolism medical schools mouse model mu-calpain novel response sensor therapeutic target

项目摘要

Abstract The prevalence of Type 2 Diabetes Mellitus (T2DM) is increasing at an alarming rate, highlighting the need to better understand the pathophysiology this syndrome. T2DM develops as a result of increased peripheral insulin resistance that develops in the setting of obesity, coupled with inadequate insulin secretion from the pancreatic β cells. A number of factors are thought to contribute to β cell death and dysfunction in T2DM including endoplasmic reticulum (ER) stress, β cell calcium dyshomeostasis and lipotoxicity resulting from increased levels of non-esterified free fatty acids (FFA). The goal of this research project is to define how FFAs alter β cell calcium (Ca2+) homeostasis and triggers the transition to a state of hyperglycemia in T2DM. The maintenance of robust levels of insulin secretion and insulin production depends on intact Ca2+ signaling in the β cell, in part patterned by the sequestration of high levels of Ca2+ within the ER lumen. Store-operated Ca2+ entry (SOCE) is a mechanism that functions to refill ER Ca2+ stores in response to ER Ca2+ depletion. SOCE is activated by the ER Ca2+ sensor STIM1, which forms complexes with plasmalemmal Orai or TRP cation channels. The formation of these complexes allows SOCE-induced Ca2+ influx from the extracellular space to refill depleted ER Ca2+ stores. Previous work in our lab has shown that β cell SOCE is impaired in T2DM due to a reduction in the expression of STIM1, leading to ER stress and reduced insulin secretion. Preliminary data have shown that lipotoxic stress induced by chronic palmitate treatment leads to dysfunctional SOCE, reduced STIM1 expression, calpain activation, and β cell death. Lastly, STIM1 ablation in INS-1 β cells led to an intracellular accumulation of lipid droplets following FFA treatment. Based on this scientific premise, this project will test the hypothesis that STIM1-induced SOCE plays a critical role in normal lipid handling in the pancreatic β cell, while dysfunctional SOCE leads to increased susceptibility to lipotoxic stress. To address this hypothesis, β-cell specific knockout mouse model of STIM1 (STIM1Δβ) and STIM1 knockout (STIM1KO) INS-1 β cells will be utilized. The goal of Aim 1 is to explore the cellular mechanisms by which loss of STIM1 leads to susceptibility to lipotoxic stress through lipid droplet accumulation, defective lipolysis, cAMP signaling and ER stress leading to calpain-induced cell death. In Aim 2, STIM1Δβ mice will be utilized to define the physiological impact of the loss of β cell STIM1 on whole body glucose homeostasis in response to a high-fat diet. Taken together, this study will provide a novel mechanistic insight into SOCE as a potential therapeutic target in the progressive development of T2DM. This fellowship award will support two years of graduate research training and two years of clinical training in the Medical Scientist Training Program (MSTP) of Indiana University (IU) School of Medicine, under the mentorship of Dr. Carmella Evans-Molina. The active, collaborative environment of IU Center for Diabetes and Metabolic Diseases (CDMD) will ensure a successful training program.

抽象的 2型糖尿病（T2DM）的患病率正在以惊人的速度增加，这突出了需要更好地了解该综合征的病理生理学。 T2DM由于周围增加而发展在肥胖的环境中发展的胰岛素抵抗，再加上胰岛素的分泌不足胰腺β细胞。人们认为许多因素会导致T2DM中的β细胞死亡和功能障碍包括内质网（ER）应激，β细胞钙的dyshomeostasis和脂肪毒性，由脂肪毒性产生非酯化游离脂肪酸（FFA）的水平增加。该研究项目的目的是定义FFA 改变β细胞钙（Ca2+）稳态，并触发T2DM中高血糖状态的过渡。这维持鲁棒水平的胰岛素分泌和胰岛素的产生取决于完整的Ca2+信号传导 β细胞，部分是由ER管腔内高水平Ca2+固相的图案。商店经营的CA2+ 进入（SOCE）是一种响应ER Ca2+耗竭来重新填充ER Ca2+存储的机制。 SOCE 由ER Ca2+传感器stim1激活，后者用纤溶酶或trp阳离子形成复合物频道。这些配合物的形成允许从细胞外空间到SOCE引起的Ca2+影响补充耗尽的ER Ca2+存储。我们实验室的先前工作表明，β细胞SOCE在T2DM中受到了损害降低了Stim1的表达，导致ER应力并减少胰岛素分泌。初步数据已经表明，由慢性棕榈酸酯治疗诱导的脂肪毒性应激导致功能障碍，减少 STIM1表达，钙蛋白酶激活和β细胞死亡。最后，INS-1β细胞中的刺激消融导致 FFA处理后，脂质液滴的细胞内积累。基于这个科学前提，这个项目将检验以下假设，即刺激刺激的SOCE在胰腺中的正常脂质处理中起着至关重要的作用 β细胞，而功能失调的SOCE导致对脂肪毒性应激的敏感性增加。解决这个问题假设，Stim1的β细胞比敲除小鼠模型（stim1Δβ）和Stim1基因敲除（STIM1KO）INS-1 β细胞将被利用。目标1的目的是探索刺激损失导致的细胞机制通过脂质液滴积累，缺陷脂解，cAMP信号和ER易感性应激的敏感性压力导致钙蛋白酶引起的细胞死亡。在AIM 2中，STIM1Δβ小鼠将用于定义生理 β细胞Stim1丧失对高脂饮食的全身葡萄糖稳态的影响。拍摄总之，这项研究将为SOCE提供一种新颖的机械洞察力，以此作为潜在的治疗靶点 T2DM的渐进发展。该奖学金奖将支持两年的研究生研究培训以及印第安纳大学（IU）的医学科学培训计划（MSTP）的两年临床培训医学院，在Carmella Evans-Molina博士的心态下。积极的协作环境 IU糖尿病和代谢疾病中心（CDMD）将确保成功的培训计划。