Secretagogue and Gi/o-GPCR signaling through the islet Na+/K+-ATPase in health and diabetes

健康和糖尿病中通过胰岛 Na /K -ATP 酶的促分泌素和 Gi/o-GPCR 信号传导

基本信息

批准号：
10717045
负责人：
David Aaron Jacobson
金额：
$ 50.57万
依托单位：
VANDERBILT UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2023
资助国家：
美国
起止时间：
2023-08-24 至 2027-04-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10717045
关键词：
Ablation Animal Disease Models Beta Cell Cell membrane Cell physiology Cells Complex Coupled Cyclic AMP-Dependent Protein Kinases D Cells Data Data Set Diabetes Mellitus Exposure to Functional disorder G Protein-Coupled Receptor Signaling G-Protein-Coupled Receptors Gene Expression Genes Glucose Goals Health High Fat Diet Homeostasis Hormone secretion Human Inflammation Insulin Insulin Receptor Insulin Resistance Ion Channel Islet Cell Islets of Langerhans K ATPase Knowledge Laboratory Finding Mediating Membrane Potentials Metabolic stress Mus Non-Insulin-Dependent Diabetes Mellitus Paracrine Communication Pathway interactions Patients Phosphorylation Physiological Protein Tyrosine Kinase Proteins Pump Reactive Oxygen Species Receptor Inhibition Receptor Signaling Regulation Research Project Grants Role Signal Transduction Somatostatin Stress Testing Time Tissues Transgenic Mice Work blood glucose regulation cytokine diabetes pathogenesis diabetic diabetogenic glycemic control inhibitor insight insulin receptor tyrosine kinase insulin secretion insulin signaling islet knock-down new therapeutic target pharmacologic protein complex receptor response src-Family Kinases therapeutic target transcriptome sequencing type I and type II diabetes voltage

项目摘要

Project Summary Islet glucose-stimulated insulin and somatostatin (SST) secretion are perturbed in patients with type-2 diabetes (T2D) and in animal models of the disease, which contributes to disrupted glucose homeostasis. It is generally accepted that secretagogues stimulate hormone secretion from -cells and -cells in response to elevated intra- cellular Ca2. However, the mechanisms that control inhibition of islet Ca2+ handling via Gi/o-coupled receptors (Gi/o-GPCRs) and how they are altered in T2D are largely unknown. Data from our lab finds that Gi/o-GPCRs reduce islet Ca2+ entry via Src tyrosine kinase-mediated activation of Na+/K+-ATPase (NKA), which hyperpolarizes membrane potential (Δψp) and limits insulin secretion. Further data show that Protein kinase A (PKA) activation by Gs-coupled receptors inhibits islet NKA activity and stimulates Ca2+ entry. Moreover, we find that islet SST provides paracrine signaling that slows glucose-stimulated -cell Ca2+ oscillations via oscillations in NKA activity, which depends on the action of Src tyrosine kinase and PKA. Finally, our preliminary data provide the first evidence that diabetic conditions diminish islet NKA activity, which contributes to perturbations in glucose and GPCR control of Ca2+ handling. Based on these exciting preliminary data, the overall objective of this pro- posal is to elucidate how islet NKA is controlled and becomes disrupted during the pathogenesis of diabetes. This project will test the central hypothesis that that islet NKA activation by tyrosine kinases limits Ca2+ entry and hormone secretion through Δψp hyperpolarization; whereas, PKA inhibition of islet NKAs enhances Ca2+ entry and hormone secretion by depolarizing Δψp. The rationale that underlies this project is that understanding sig- naling that integrates NKA modulation of islet cell Ca2+ handling and hormone secretion will expose novel thera- peutic targets for restoring glucose-stimulated hormone secretion in T2D. This project will be accomplished with the following two specific aims: 1) Determine the mechanisms regulating NKA control of β-cell function in health and diabetes; and 2) Determine how NKA modulates -cell function and dysfunction. Under the first aim, trans- genic mice with -cell ablation of the - - and -subunits of the NKA complex subunits as well as human -cells with knockdown of NKA - - and -subunits will be utilized to assess the roles of NKA during secretagogue and Gi/o-GPCR modulation of -cell Ca2+ handling and insulin secretion. Aim1 will also determine how diabetic con- ditions impact NKA signaling and insulin secretion. Under the second aim, NKA control of -cell Ca2+ handling and function will be determined in mice with -cell specific ablation of NKA - - and -subunits or in human pseudoislets with -cell specific knockdown of NKA - - and -subunits. Furthermore, Aim2 will determine how reduced NKA function in -cells under the stressful conditions associated with diabetes contributes to -cell dysfunction. This project is significant because it is expected to illuminate mechanisms that alter -cell and -cell Ca2+ handling and disrupt islet hormone secretion in T2D. Moreover, this project plans to identify potential phar- macological strategies for normalizing islet hormone secretion and reducing islet dysfunction in T2D.

项目概要 2 型糖尿病患者的胰岛葡萄糖刺激胰岛素和生长抑素 (SST) 分泌受到干扰 (T2D) 和该疾病的动物模型中，这会破坏葡萄糖稳态。公认促分泌剂刺激  细胞和  细胞的激素分泌，以响应体内升高的反应然而，通过 Gi/o 偶联受体控制抑制胰岛 Ca2+ 处理的机制。 (Gi/o-GPCR) 以及它们在 T2D 中如何改变在很大程度上是未知的。我们实验室的数据发现 Gi/o-GPCR。通过 Src 酪氨酸激酶介导的 Na+/K+-ATPase (NKA) 激活减少胰岛 Ca2+ 进入，进一步的数据表明，蛋白激酶 A 使膜电位 (Δψp) 超极化并限制胰岛素分泌。 Gs 偶联受体 (PKA) 激活可抑制胰岛 NKA 活性并刺激 Ca2+ 进入。胰岛 SST 提供旁分泌信号，通过振荡减缓葡萄糖刺激的  细胞 Ca2+ 振荡 NKA 活性取决于 Src 酪氨酸激酶和 PKA 的作用。最后，我们提供了初步数据。第一个证据表明糖尿病会降低胰岛 NKA 活性，从而导致血糖波动和 GPCR 对 Ca2+ 处理的控制基于这些令人兴奋的初步数据，该项目的总体目标是 posal 的目的是阐明胰岛 NKA 在糖尿病发病过程中如何受到控制和破坏。该项目将测试中心假设，即酪氨酸激酶激活胰岛 NKA 限制 Ca2+ 进入并通过 Δψp 超极化分泌激素；而 PKA 抑制胰岛 NKA 可增强 Ca2+ 的进入；通过去极化 Δψp 和激素分泌该项目的基本原理是理解信号。整合 NKA 对胰岛细胞 Ca2+ 处理和激素分泌的调节的 naling 将揭示新的治疗方法该项目将通过恢复 T2D 中葡萄糖刺激的激素分泌来实现。以下两个具体目标： 1) 确定健康中 NKA 控制 β 细胞功能的调节机制和糖尿病；以及 2) 确定 NKA 如何调节  细胞功能和功能障碍。 NKA 复合体亚基的 - - 和 - 亚基以及人类 -细胞的  细胞消融的基因小鼠随着NKA - - 和- 亚基的敲低，将用于评估NKA 在促分泌素和 Gi/o-GPCR 对  细胞 Ca2+ 处理和胰岛素分泌的调节也将决定糖尿病如何发生。第二个目标是 NKA 控制  细胞 Ca2+ 处理。和功能将在具有NKA α- β-和-亚基的细胞特异性消融的小鼠或人类中确定具有  细胞特异性敲除 NKA - - 和 - 亚基的伪胰岛此外，Aim2 将确定如何进行。在与糖尿病相关的压力条件下， 细胞中 NKA 功能的降低有助于  细胞该项目意义重大，因为它有望阐明改变  细胞和  细胞的机制。此外，该项目计划确定潜在的药物。使胰岛激素分泌正常化和减少 T2D 胰岛功能障碍的宏观策略。