Mechanisms of Somatostatin-Mediated Inhibition of Insulin and Glucagon

生长抑素介导的胰岛素和胰高血糖素抑制机制

• 批准号: 10642738
• 负责人: Ryan Hart
• 金额: $ 4.01万
• 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: 2022-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10642738
• 关键词: Actins; Address; Affect; Agonist; Alpha Cell; American; Attenuated; Automobile Driving; Beta Cell; Calcium; Cell surface; Cells; Cilia; Complement; Complex; Coupled; Cyclic AMP; Data; Diabetes Mellitus; Endocrine System Diseases; Exocytosis; F-Actin; Family; Functional Imaging; GTP-Binding Proteins; Genetic Transcription; Glucagon; Glucose; Guanosine Triphosphate Phosphohydrolases; Hormone secretion; Hormones; Hyperinsulinism; Hypoglycemia; Image; Individual; Insulin; Islet Cell; Islets of Langerhans; Kinetics; Knowledge; Mechanics; Mediating; Metabolic; Mission; Molecular; Monomeric GTP-Binding Proteins; Mus; National Institute of Diabetes and Digestive and Kidney Diseases; Outcome; Paracrine Communication; Polymers; Population; Public Health; Quality of life; Receptor Activation; Reporter; Research; Resolution; Role; SSTR2 gene; SSTR3 gene; Secretory Vesicles; Signal Transduction; Somatostatin; Somatostatin Receptor; Specificity; Structure of beta Cell of islet; Testing; Time; Tissues; Transgenic Mice; United States; Weight; antagonist; attenuation; cell type; experimental study; imaging approach; improved; innovation; insulin secretion; islet; live cell imaging; next generation sequencing; novel; peptide hormone; pharmacologic; polymerization; receptor; response; rho; selective expression; sensor; somatostatin receptor 1; spatiotemporal; targeted treatment; transcriptome; transcriptomics; type I and type II diabetes

Somatostatin (SST) is a major inhibitory hormone that is capable of attenuating both glucagon and insulin secretion from alpha (α) and beta (β) cells respectively within the pancreatic islet of Langerhans. However, there is a critical gap in our understanding of the basic signaling mechanisms downstream of Somatostatin Receptor (SSTR) activation, and how these favor the inhibition of insulin secretion under some circumstances and the inhibition of glucagon secretion under others. Through transcriptomic analysis of purified α and β cell populations I have identified key differences and potential similarities between both which may begin to explain their cell specific SST response. Central to these observations, the SSTR profile which provides the input signal between either cell type is fundamentally different between α and β cells, with both cell types expressing SSTR3 on primary cilia, while α cells additionally express SSTR2 on their cell surface. Somatostatin signaling is typically suggested to lead to the inhibition of calcium and/or cAMP in the islet, but the relative importance of SST’s effect on these parallel signaling cascades is not understood. Furthermore, I have identified a novel SSTR mediated effector mechanism that actively drives the remodeling of filamentous actin (F-actin) with implications for secretory granule exocytosis. As such, my central hypothesis is that selective activation of SSTR3 on β cells and SSTR2 or SSTR3 on α cells will attenuate insulin and glucagon secretion via distinct effects on the quality and kinetics of Ca2+ and cAMP responses and downstream F-actin polymerization. I will pursue this hypothesis through two separate aims anchored by high throughput functional imaging of intact islets. First, I will leverage transgenic mouse lines in which fluorescent reporters of secondary messengers will be delivered to strictly α or β cells. These islets will then be subjected to individual SSTR agonists and antagonists to understand the individual contributions of identified cell specific SSTRs. Second, fluorescent reporters of F-actin dynamics will be employed in live imaging experiments to functionally determine the contribution of SSTR activation on F-actin polymerization and remodeling. These results will be coupled next generation sequencing data of purified populations of α and β cells treated with SST and SSTR type specific antagonists. The results of this aim will characterize an underlying F-actin response to SST contributing to overall hormone attenuation. These approaches are innovative as they leverage the power of high throughput functional imaging of large populations of cells to characterize both a novel mechanism and cell type specific response in high resolution. Collectively, the results of these aims are significant as they will result in a more complete understanding of the mechanisms by which SST succeeds in attenuating insulin and glucagon release under different metabolic conditions. This understanding carries significant weight in developing cell specific SSTR agonists aimed at attenuating specific cell populations, with implications in targeted treatment of type I and II diabetes affecting over 30 million individuals in the United States of America.

生长抑素（SST）是一种主要的抑制激素，能够减轻胰高血糖素和胰岛素 兰格汉胰岛内分别从α（α）和β（β）细胞分泌。但是，那里 是我们对生长抑素受体下游的基本信号传导机制的理解的关键差距 （SSTR）激活，以及它们如何在某些情况下抑制胰岛素分泌的抑制 抑制其他人的牙齿分泌。通过纯化的α和β细胞种群的转录组分析 我已经确定了可能开始解释其细胞的关键差异和潜在的相似性 具体的SST响应。这些观察结果的核心，​​提供的SSTR曲线提供了输入信号 α和β细胞之间的任何一种细胞类型都在根本上不同，两种细胞类型都表达SSTR3 原发性纤毛，而α细胞还在其细胞表面表达SSTR2。生长抑素信号通常是 建议导致胰岛抑制钙和/或营地，但SST效应的相对重要性 在这些平行信号传导上，尚不清楚级联反应。此外，我已经确定了一种新颖的SSTR介导 效应子机制积极驱动丝状肌动蛋白（F-肌动蛋白）的重塑，对 分泌颗粒胞吐作用。因此，我的中心假设是SSTR3在β细胞上的选择性激活 α细胞上的SSTR2或SSTR3会通过对质量的明显影响减弱胰岛素和谷歌分泌 以及Ca2+和CAMP反应的动力学以及下游F-肌动蛋白聚合。我将追求这个假设 通过两个独立的目标，由完整胰岛的高吞吐量功能成像锚定。首先，我会利用 转基因小鼠线，其中次级信使的荧光记者将被传递到严格的α或 β细胞。然后，这些胰岛将受到单个SSTR激动剂和对手的影响 已识别的细胞特异性SSTR的个人贡献。第二，F-肌动力学的荧光记者将 被用于实时成像实验，以确定SSTR激活对F-肌动蛋白的贡献 聚合和重塑。这些结果将耦合下一代测序数据的纯化数据 用SST和SSTR型特异性拮抗剂处理的α和β细胞的群体。这个目标的结果将 表征了对SST的基本F-肌动蛋白反应，从而导致整体骑马衰减。这些 方法是创新的，因为它们利用大量人群的高吞吐量功能成像的力量 细胞以高分辨率表征新型机制和细胞类型特异性反应。共同 这些目标的结果很重要，因为它们将对机制有更完整的了解 在不同的代谢条件下，SST成功地减弱了胰岛素和胰高血糖素的释放。这 理解在开发特定细胞的SSTR激动剂方面具有显着的重量 细胞种群，对I型和II型糖尿病的有针对性治疗产生影响超过3000万 美国个人。