FFA4 regulation of pancreatic islet function

FFA4对胰岛功能的调节

• 批准号: 10590625
• 负责人: Mark O. Huising
• 金额: $ 48.47万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-04-01 至 2026-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10590625
• 关键词: Ablation; Address; Adult; Agonist; American; B Cell Proliferation; B-Lymphocytes; Beta Cell; Cell Proliferation; Cell physiology; Cells; Complement; Coupled; Couples; Cyclic AMP; D Cells; Data; Diabetes Mellitus; Disease; Disease Management; Drug Targeting; Feedback; Functional Imaging; G-Protein-Coupled Receptors; GTP-Binding Proteins; Gases; Generations; Genetic; Glucagon; Goals; Half-Life; Health; Hormone secretion; Hormones; Insulin; Insulin Resistance; Insulin deficiency; Interruption; Islet Cell; Islets of Langerhans; Kinetics; Laboratories; Mediating; Mission; National Institute of Diabetes and Digestive and Kidney Diseases; Non-Insulin-Dependent Diabetes Mellitus; Pancreas; Pathway interactions; Patients; Peripheral; Pharmaceutical Preparations; Physiological; Prediabetes syndrome; Proliferating; Protein Isoforms; Protein Subunits; Public Health; Publishing; Quality of life; Regulation; Research; Research Proposals; Resolution; Role; Signal Transduction; Small Interfering RNA; Somatostatin; Testing; Therapeutic Intervention; Toxin; Validation; cell type; diabetes management; diabetes mellitus therapy; experimental study; improved; innovation; insulin secretion; islet; long chain fatty acid; mimetics; new therapeutic target; novel; novel therapeutics; pancreatic islet function; paracrine; pharmacologic; preservation; programs; receptor; response; targeted treatment; therapeutic target

Half of US adults have diabetes or pre-diabetes, illustrating a critical need for novel diabetes treatments. There is a fundamental gap in the understanding of the paracrine feedback in control of insulin and glucagon secretion. The long-term goal of the research program is to elucidate the key players in (patho)physiological crosstalk within pancreatic islets in order to identify novel therapeutic targets. The overall objective in this application is to understand the mechanisms of action for the long chain fatty acid receptor 4 (FFA4). This G protein-coupled receptor is a promising T2D drug target that increases insulin secretion. However, there is conflicting information with regards to the islet cell type(s) involved in the salutary actions of FFA4. The central hypothesis is that within pancreatic islets FFA4 is predominantly expressed in d cells where its activation inhibits somatostatin (SST) release and alleviates tonic inhibition of insulin and glucagon secretion. This hypothesis was formulated on the basis of preliminary and recently published data produced collaboratively in the laboratories of both PIs that place FFA4 expression predominantly on d cells. Furthermore, FFA4 stimulation inhibits d cells and stimulates cAMP, Ca2+ and hormone secretion in b and a cells - effects that depend on d cell expression of FFA4. Nevertheless, FFA4 agonists stimulate b cell proliferation independently of d cells and others claim direct FFA4 stimulation of b cells. The rationale for the proposed research is to definitively resolve the mechanism(s) by which FFA4 agonists promote insulin and glucagon secretion and beta cell proliferation. This hypothesis will be tested in 3 specific aims. Aim 1 tests the hypothesis that FFA4 activation in d cells lowers cAMP generation and inhibits SST secretion, which indirectly enhances cAMP generation in b and a cells to stimulate insulin and glucagon secretion, respectively. SST will be deleted genetically, or d cells will be ablated by diphteria toxin, to determine if stimulation of FFA4 stimulates b and a cells if 1) SST is deleted, 2) d cells are ablated. Aim 2 test the hypothesis that direct FFA4 activation of a or b cells has minimal impact on hormone secretion, but promotes b-cell proliferation. FFA4 will be selectively deleted in a or b cells to determine whether FFA4-induced hormone release, cAMP generation, or proliferation is a or b cell-autonomous. Aim 3 tests the hypothesis that FFA4 couples to Gaz in d cells to inhibit SST secretion and to Gas in a and/or b cells to stimulate b-cell proliferation. The G proteins involved in FFA4-mediated islet responses will be identified by genetic deletion of Gaz in specific islet cells combined with pharmacological inhibition and siRNA-mediated silencing of select G-protein isoforms. The research is conceptually and technically innovative as it evaluates the important physiological role of d cells within intact islets in attenuating a- and b-cell activity and applies sophisticated functional imaging to quantify the kinetics of cAMP and Ca2+ in a, b, and d cells at single cell resolution within intact islets. These experiments provide previously unattainable single-cell resolution combined with approaches to experimentally interrupt SST-mediated intra-islet feedback to elucidate the mechanisms that underlie the beneficial effects of FFA4 stimulation on insulin secretion and b-cell proliferation. This is significant because a full mechanistic understanding of the pathways that mediate the salutary actions of FFA4 will inform new therapies to improve and preserve functional b-cell mass and insulin secretory capacity.

我们一半的成年人患有糖尿病或糖尿病前，这说明了对新型糖尿病治疗的迫切需求。有一个 在控制胰岛素和胰高血糖素分泌的旁分泌反馈方面的基本差距。长期 研究计划的目标是阐明胰岛内（Patho）生理串扰的主要参与者 确定新颖的治疗靶标。该应用程序的总体目的是了解行动机制 长链脂肪酸受体4（FFA4）。该G蛋白偶联受体是一个有希望的T2D药物靶标，可增加 胰岛素分泌。但是，关于有益的胰岛细胞类型存在冲突的信息 FFA4的动作。中心假设是，胰岛内FFA4内主要表达在D细胞中 它的激活抑制生长抑素（SST）释放，并减轻胰岛素和胰高血糖素分泌的补品抑制作用。这 假设是基于初步和最近发布的数据提出的。 将FFA4表达的两个PI的实验室主要在D细胞上。此外，FFA4刺激抑制D 细胞并刺激B和A细胞中cAMP，Ca2+和激素分泌 - 依赖于FFA4的D细胞表达的作用。 然而，FFA4激动剂独立于D细胞刺激B细胞增殖，而其他人则声称直接FFA4刺激 B细胞。拟议研究的理由是确定解决FFA4激动剂的机制 促进胰岛素和胰高血糖素的分泌以及β细胞增殖。该假设将以3个特定目的进行检验。目标1 检验以下假设：D细胞中的FFA4激活降低营地的产生并抑制SST分泌，这间接 分别增强B和A细胞中的营地产生，分别刺激胰岛素和胰高血糖素的分泌。 SST将被删除 遗传上或D细胞将被双二毒素消融，以确定FFA4的刺激是否刺激B和A细胞，如果1） SST被删除，2）D细胞被消融。 AIM 2检验了A或B细胞的直接FFA4激活的假设最小 对激素分泌的影响，但促进了B细胞增殖。 FFA4将在A或B细胞中选择性删除以确定 FFA4诱导的激素释放，cAMP产生还是增殖都是或B细胞自主。 AIM 3测试 假设FFA4偶联到D细胞中的Gaz，以抑制SST分泌和A和/或B细胞中的气体，以刺激B细胞 增殖。与FFA4介导的胰岛反应相关的G蛋白将通过在遗传缺失中鉴定 特定的胰岛细胞结合了某些G蛋白同工型的药理抑制和siRNA介导的沉默。 该研究在概念和技术上都是创新的，因为它评估了D细胞在 完整的胰岛衰减A和B细胞活性，并应用复杂的功能成像来量化 在完整胰岛内的单细胞分辨率下A，B和D细胞中的CAMP和Ca2+。这些实验先前提供 无法获得的单细胞分辨率与实验中断SST介导的ISLET反馈的方法相结合 阐明FFA4刺激对胰岛素分泌和B细胞的有益作用的机制 增殖。这很重要，因为对介导有益行动的途径有充分的机械理解 FFA4将告知新疗法，以改善和保留功能性B细胞质量和胰岛素分泌能力。