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

胰腺细胞库操作的钙进入在脂肪酸代谢中的作用

• 批准号: 10470167
• 负责人: Paul Sohn
• 金额: $ 3.26万
• 依托单位: TRUSTEES OF INDIANA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-09 至 2023-04-21
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10470167
• 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; Pancreas; 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; diet-induced obesity; 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; lipidomics; medical schools; mouse model; mu-calpain; novel; response; sensor; therapeutic target

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.

摘要 2型糖尿病（T2 DM）的患病率正在以惊人的速度增加，这突出了需要 更好地了解这种综合征的病理生理学。T2 DM的发生是由于外周血 胰岛素抵抗是在肥胖的情况下发展起来的，再加上从胰岛素分泌不足， 胰腺β细胞许多因素被认为有助于T2 DM中的β细胞死亡和功能障碍 包括内质网（ER）应激、β细胞钙稳态失调和脂毒性， 非酯化游离脂肪酸（FFA）水平增加。本研究项目的目标是定义FFA如何 改变β细胞钙（Ca 2+）稳态并触发T2 DM向高血糖状态的转变。的 胰岛素分泌和胰岛素产生的稳定水平的维持依赖于细胞内完整的Ca 2+信号传导。 β细胞，部分通过ER腔内高水平Ca 2+的隔离而形成。钙池操作 进入（SOCE）是响应于ER Ca 2+耗尽而重新填充ER Ca 2+储存的机制。SOCE 由ER Ca 2+传感器STIM 1激活，STIM 1与质膜奥赖或TRP阳离子形成复合物 渠道这些复合物的形成允许SOCE诱导的Ca 2+从细胞外空间流入， 补充耗尽的ER Ca 2+储存。我们实验室先前的工作表明，T2 DM患者β细胞SOCE受损， STIM 1表达减少，导致ER应激和胰岛素分泌减少。初步数据 已经表明，由慢性棕榈酸酯治疗诱导的脂毒性应激导致功能失调的SOCE，降低 STIM 1表达、钙蛋白酶激活和β细胞死亡。最后，INS-1 β细胞中的STIM 1消融导致了 FFA处理后脂滴的细胞内积累。基于这一科学前提，该项目 将检验STIM 1诱导的SOCE在胰腺正常脂质处理中起关键作用的假设， β细胞，而功能失调的SOCE导致对脂毒性应激的易感性增加。为了解决这个 假设，STIM 1（STIM 1 Δβ）和STIM 1敲除（STIM 1 KO）INS-1 β细胞特异性敲除小鼠模型 将使用β细胞。目的1的目标是探索STIM 1缺失导致的细胞机制， 通过脂滴积聚、脂肪分解缺陷、cAMP信号传导和ER对脂毒性应激的易感性 压力导致钙蛋白酶诱导的细胞死亡。在目标2中，将使用STIM 1 Δβ小鼠来定义生理学上的 β细胞STIM 1的缺失对高脂饮食引起的全身葡萄糖稳态的影响。采取 总之，这项研究将提供一个新的机制洞察SOCE作为一个潜在的治疗目标，在 T2 DM的进展。该奖学金将支持两年的研究生研究培训 并在印第安纳州大学（IU）的医学科学家培训计划（MSTP）中接受了两年的临床培训 医学院，在Carmella Evans-Molina博士指导下。积极、协作的环境 IU糖尿病和代谢疾病中心（CDMD）的负责人将确保培训计划的成功。