Two-Pore-Domain Potassium Channels as Novel Targets for Modulating Islet Hormone Secretion

2型糖尿病(T2 DM)患者和动物的胰岛素和胰高血糖素分泌紊乱 疾病的模型，这部分是由于胰岛细胞钙稳态的扰动。而两孔- 结构域K+(K2P)通道是胰岛细胞处理钙离子和激素分泌的关键调节因子。 对于这些通道如何控制人类胰岛功能和功能障碍，我们的理解存在差距 糖尿病的情况。这项研究的长期目标是确定靶向治疗的潜力。 用于治疗糖尿病和防止细胞破坏的K2P通道。这个项目的总体目标是 阐明促分泌剂依赖的胰岛钙内流调节的分子机制。 单核细胞通过K2P通道分泌。该项目将检验人类胰岛K2P通道的中心假设 调节细胞质和内质网钙离子的处理，从而调节激素的分泌 糖尿病条件下的细胞内质网应激反应。这个项目得到了强劲的初步数据的支持 这已经确定Talk-1是人类和啮齿动物-细胞内质网钙离子处理、有丝分裂-1的重要决定因素。 软骨功能和胰岛素分泌。已确定Talk-1相关通道的进一步数据 Talk-2还控制内质网钙稳态，并且在人的胰岛中高表达。最后，初步数据 研究发现，K2P通道TASK-1和TALK-2控制细胞内质网钙离子的储存和胰升糖素的分泌。这个 支持这项研究的理论基础是，了解胰岛激素分泌是如何受到影响的 通过K2P通道的活性将为减少细胞衰竭和高血糖提供新的治疗靶点。 探讨2型糖尿病的发病机制。该项目将以以下两个具体目标完成：1)消除 终止Talk-1和Talk-2通道随时间和时间推移如何调节细胞功能和功能障碍 以及2)确定TASK-1和Talk-2通道如何控制胰腺细胞的胰升糖素分泌。 在第一个目标下，人类-细胞谈话通道的功能将以显性否定进行评估 (D/N)和shRNA方法，已在申请人手中确立为可行。此外，老鼠 通过可诱导的细胞消融Talk-1将被用来测试这些通道对葡萄糖代谢的影响。 胃动素。细胞通话通道的作用将在生理条件下以及在 体内和/或体外与糖尿病相关的应激条件。在第二个目标下，转基因小鼠 缺乏TASK-1以及细胞特有的D/N和shRNA方法将被用来评估角色 TASK-1在人和小鼠细胞钙处理和胰升糖素分泌过程中的作用。最后，Talk-2频道 人类细胞功能的控制将通过胰岛细胞选择性D/N和基因敲除来确定，以监测其 对钙稳态和胰升糖素分泌的影响。这个项目意义重大，因为它预计将照明- Nate调节胰岛素和胰高血糖素分泌以及降低细胞ER的药理策略 应激；它对于发现治疗2型糖尿病患者血糖紊乱和减少细胞衰竭的治疗方法至关重要。

Insulin and glucagon secretion are disrupted in patients with type-2 diabetes mellitus (T2DM) and in animal models of the disease, which is due in part to perturbations in islet-cell Ca2+ homeostasis. While two-pore- domain K+ (K2P) channels are key regulators of pancreatic islet-cell Ca2+ handling and hormone secretion, there is a gap in our understanding of how these channels control human islet function and dysfunction under diabetic conditions. The long term goal of this research is to determine the therapeutic potential of targeting K2P channels for treating diabetes and preventing -cell destruction. The overall objective of this project is to elucidate molecular mechanisms regulating secretagogue dependent modulation of islet Ca2+ influx and hor- mone secretion via K2P channels. This project will test the central hypothesis that human islet K2P channels modulate cytoplasmic and endoplasmic reticulum Ca2+ handling, thus, regulating hormone secretion as well as the -cell ER-stress response under diabetic conditions. This project is supported by strong preliminary data that has identified TALK-1 as an important determinant of human and rodent -cell ER Ca2+ handling, mito- chondrial function, and insulin secretion. Further data that has determined that the TALK-1 related channel TALK-2 also controls ER Ca2+ homeostasis and is highly expressed in human islets. Finally, preliminary data finds that the K2P channels, TASK-1 and TALK-2, control -cell ER Ca2+ storage and glucagon secretion. The rationale that underlies the proposed research is that understanding how islet hormone secretion is influenced by K2P channel activity will expose novel therapeutic targets for reducing -cell failure and hyperglycemia dur- ing the pathogenesis of T2DM. This project will be accomplished with the following two specific aims: 1) De- termine how TALK-1 and TALK-2 channels modulate -cell function and dysfunction over time and under stress; and 2) Determine how TASK-1 and TALK-2 channels control of pancreatic -cell glucagon secretion. Under the first aim, the function of human-cell TALK channels will be assessed with a dominant negative (D/N) and ShRNA approach, which have been established as feasible in the applicants’ hands. Moreover, mice with inducible -cell ablation of TALK-1 will be utilized to test the influences of these channels on glucose ho- meostasis. The roles of -cell TALK channels will be assessed under physiological conditions as well as under the stressful conditions associated with diabetes in vivo and/or in vitro. Under the second aim, transgenic mice deficient for TASK-1 as well as a -cell specific D/N and ShRNA approaches will be utilized to assess the roles of TASK-1 during human and mouse -cell Ca2+ handling and glucagon secretion. Finally, TALK-2 channel control of human -cell function will be determined with islet-cell selective D/N and knockdown to monitor their impact on Ca2+ homeostasis and glucagon secretion. This project is significant because it is expected to illumi- nate pharmacological strategies for regulating insulin and glucagon secretion as well as reducing -cell ER- stress; it is essential for uncovering therapies for treating dysglycemia and reducing -cell failure in T2DM.