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

胰岛素和胰高血糖素分泌在2型糖尿病（T2 DM）患者和动物中被破坏 这部分是由于胰岛细胞Ca 2+稳态的扰动。而两孔- 结构域K+（K2 P）通道是胰岛细胞Ca 2+处理和激素分泌的关键调节剂， 我们对这些通道如何控制人类胰岛功能和功能障碍的理解存在差距， 糖尿病状况。这项研究的长期目标是确定靶向治疗的潜力。 K2 P通道用于治疗糖尿病和防止胰岛细胞破坏。该项目的总体目标是 阐明促分泌素依赖性调节胰岛Ca 2+内流和hor的分子机制。 通过K2 P通道分泌激素。该项目将测试人类胰岛K2 P通道的中心假设， 调节细胞质和内质网Ca 2+处理，从而调节激素分泌以及 糖尿病条件下的胰岛细胞ER应激反应。该项目得到了强有力的初步数据的支持 已经确定TALK-1是人类和啮齿类动物内质网钙离子处理的重要决定因素， 以及胰岛素分泌。确定TALK-1相关信道的进一步数据 TALK-2还控制ER Ca 2+稳态，并在人胰岛中高度表达。最后，初步数据 发现K2 P通道，ASK-1和TALK-2，控制胰岛细胞ER Ca 2+储存和胰高血糖素分泌。的 这项研究的基本原理是了解胰岛激素分泌是如何受到影响的， 通过K2 P通道活性将揭示新的治疗靶点，以减少胰岛细胞衰竭和高血糖症， 2型糖尿病的发病机制。该项目将完成以下两个具体目标：1）德- TALK-1和TALK-2通道如何随时间和条件调节β细胞功能和功能障碍 应激;和2）确定ASK-1和TALK-2通道如何控制胰腺β细胞胰高血糖素分泌。 在第一个目标下，将用显性阴性来评估人胰岛细胞TALK通道的功能。 （D/N）和ShRNA方法，这些方法在申请人手中已经确定是可行的。此外，老鼠 TALK-1的诱导性β细胞消融将用于测试这些通道对葡萄糖HO-1的影响。 体内平衡将在生理条件下以及在体外条件下评估细胞TALK通道的作用。 与体内和/或体外糖尿病相关的应激条件。在第二个目标下， 缺乏的TASK-1，以及一个β细胞特异性的D/N和shRNA的方法将被用来评估的作用， 在人类和小鼠胰岛β细胞Ca 2+处理和胰高血糖素分泌过程中，最后，TALK-2频道 人类胰岛细胞功能的控制将通过胰岛细胞选择性D/N和敲低来确定， 影响Ca 2+稳态和胰高血糖素分泌。该项目意义重大，因为它预计将照亮- 调节胰岛素和胰高血糖素分泌以及减少胰岛细胞ER的天然药理学策略， 它对于发现治疗2型糖尿病的代谢障碍和减少β细胞衰竭的疗法至关重要。

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.