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

• 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
• 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

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.

项目摘要 葡萄糖刺激的胰岛素和生长抑素（SST）分泌在2型糖尿病患者中受到干扰 （T2D）和该疾病的动物模型，这导致葡萄糖稳态破坏。通常是 接受促进剂刺激了细胞和细胞的horsene分泌，以响应于升高的内部。 细胞Ca2。但是，通过GI/O耦合受体控制抑制胰岛Ca2+处理的机制 （GI/O-GPCR）以及如何在T2D中改变它们是未知的。来自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）的激活减少胰岛Ca2+进入，该激活 超极化膜电位（Δψp）并限制胰岛素分泌。进一步的数据表明蛋白激酶A （PKA）通过GS耦合受体激活胰岛NKA活性并刺激Ca2+进入。而且，我们发现 胰岛SST提供了旁分泌信号传导，可通过振荡减慢葡萄糖刺激的细胞Ca2+振荡 在NKA活性中，取决于SRC酪氨酸激酶和PKA的作用。最后，我们的初步数据提供商 糖尿病状况减少胰岛NKA活性的第一个证据，这有助于葡萄糖的扰动 和CA2+处理的GPCR控制。基于这些令人兴奋的初步数据，这是该计划的总体目标 POSAL是为了阐明胰岛NKA的控制方式，并在糖尿病发病机理期间被破坏。 该项目将检验一个中心假设，即酪氨酸激酶的胰岛NKA激活限制了CA2+进入和 通过Δψp超极化分泌的骑马分泌；而胰岛NKA的PKA抑制可增强Ca2+进入 通过去极化Δψp来分泌骑马。该项目的基础的理由是了解sig- 整合NKA胰岛细胞Ca2+处理和Horsene分泌的NKA调制的NALING将暴露新的thera- 用于恢复T2D中葡萄糖刺激的激素分泌的灵活靶标。这个项目将通过 以下两个具体目的：1）确定调查NKA对健康中NKA控制功能的机制 和糖尿病； 2）确定NKA如何调节细胞函数和功能障碍。在第一个目标下， NKA复合体亚基的--和亚基的基因小鼠以及人类细胞 随着NKA--的敲除，将利用nka-subunits评估NKA在秘密期间的作用 细胞Ca2+处理和胰岛素分泌的GI/O-GPCR调制。 AIM1还将决定糖尿病性如何 差异会影响NKA信号传导和胰岛素分泌。在第二个目标下，NKA控制细胞Ca2+处理 和功能将在NKA-和单块的小鼠特异性消融或人类中确定 具有NKA--和单块的pseudoislets。此外，AIM2将决定如何 在与糖尿病相关的压力状况下，细胞中NKA功能降低了细胞 功能障碍。该项目很重要，因为它有望照亮改变细胞和细胞的机制 T2D中的CA2+处理和破坏胰岛质量。此外，该项目计划确定潜在的Phar- T2D中将胰岛分泌胰岛分泌和减少胰岛功能障碍的衡量策略。