ATP-Sensitive Potassium Channels and Insulin Secretion

描述（由申请人提供）：胰岛细胞的ATP敏感性钾（KATP）通道通过将葡萄糖代谢与膜兴奋性偶联，在葡萄糖刺激的胰岛素分泌中发挥关键作用。细胞KATP通道由磺酰脲受体SUR 1和内向整流钾通道Kir6.2形成。 SUR 1和Kir6.2的功能缺失突变是先天性高胰岛素血症的主要原因。 相反，功能获得性通道突变导致相反的疾病新生儿糖尿病。我们研究的长期目标是了解细胞KATP通道的调节，这种调节在疾病中是如何受到干扰的，以及我们如何操纵通道调节来对抗胰岛素分泌障碍。迄今为止，这项赠款支持的工作已经确定了疾病背景下通道生物发生和贩运的重要性。在这个更新的应用程序中，我们建议研究如何KATP通道密度在<$-细胞膜调节生理信号，以控制胰岛素分泌。这是基于我们的初步发现，瘦素，这是已知的抑制胰岛素分泌的脂肪轴反馈调节的一部分，显着增加表面表达的KATP通道在？-细胞。本申请的主要目的是检验瘦素通过触发信号级联以增加KATP传导并抑制胰岛素分泌来促进KATP通道运输至细胞表面的假设。此外，我们建议继续努力开发能够克服突变KATP通道运输缺陷的药物，作为先天性高胰岛素血症的新治疗策略。为此，我们已经获得了几个有前途的小分子，增强通道表面表达的初步结果。因此，本申请的第二个主要目的是检验以下假设：在先天性高胰岛素血症中鉴定的运输受损的KATP突变体的表面表达和功能可以通过小分子伴侣恢复以恢复细胞功能。我们将结合联合收割机生物化学、影像学和电生理学的方法来验证上述假设。在目标1中，我们将阐明瘦素增加<$-细胞KATP通道表面表达的信号传导和细胞机制。在目标2中，我们将鉴定和表征新的药理学分子伴侣，其拯救COS细胞和啮齿动物和人类胰岛/胰岛细胞中的运输受损的KATP通道。这项研究是创新的，因为它测试了新的概念，在生理和药理学调节的KATP通道贩运在<$-细胞使用独特的工具和知识，由我们的实验室开发的这些通道。从人类健康和基础科学的角度来看，这项研究都具有重要意义。它将确定新的化合物，可以纠正由疾病突变引起的通道运输缺陷，从而赋予其高翻译潜力。此外，它将揭示新的生理信号传导机制，可用于控制KATP通道表面表达，从而在胰岛素分泌疾病患者中葡萄糖分泌偶联。 公共卫生相关性：ATP敏感性钾通道（KATP）在调节胰岛素分泌中起着重要作用，KATP通道功能障碍可导致胰岛素分泌异常，如糖尿病和高胰岛素血症。该项目的目标是了解胰腺细胞膜中丰富的通道是如何通过生理信号（如瘦素和葡萄糖）和药理学试剂调节以影响胰岛素分泌的。这项研究将导致开发新的治疗策略，治疗由通道失调引起的疾病。

DESCRIPTION (provided by applicant): ATP-sensitive potassium (KATP) channels of islet ¿-cells play a key role in glucose-stimulated insulin secretion by coupling glucose metabolism to membrane excitability. The ¿-cell KATP channel is formed by the sulfonylurea receptor SUR1 and the inward rectifier potassium channel Kir6.2. Loss-of-function mutations in SUR1 and Kir6.2 are the primary cause of congenital hyperinsulinism. In contrast, gain-of-function channel mutations cause the opposite disease neonatal diabetes. The long-term goal of our research is to understand regulation of ¿-cell KATP channels, how this regulation is perturbed in disease and how we may manipulate channel regulation to combat insulin secretion disorders. Work supported by this grant to date has established the importance of channel biogenesis and trafficking in the context of disease. In this renewal application, we propose to study how KATP channel density in the ¿-cell membrane is regulated by physiological signals to control insulin secretion. This is based on our preliminary finding that leptin, which is known to inhibit insulin secretion as part of the adipoinsular axis feedback regulation, markedly increases surface expression of KATP channels in ¿-cells. A major goal of this application is to test the hypothesis that leptin promotes KATP channel trafficking to the cell surface by triggering a signaling cascade to increase KATP conductance and inhibit insulin secretion. In addition, we propose to continue our efforts on developing pharmacological agents that can overcome the trafficking defects of mutant KATP channels as a novel therapeutic strategy for congenital hyperinsulinism. To this end, we have obtained preliminary results on several promising small molecules that enhance channel surface expression. Thus, a second major goal of this application is to test the hypothesis that surface expression and function of trafficking-impaired KATP mutants identified in congenital hyperinsulinism can be restored by small molecule chaperones to recover ¿-cell function. We will combine biochemical, imaging and electrophysiology approaches to test the above hypotheses. In Aim 1, we will elucidate the signaling and cellular mechanisms by which leptin increases surface expression of ¿-cell KATP channels. In Aim 2, we will identify and characterize novel pharmacological chaperones that rescue trafficking-impaired KATP channels in COS cells and rodent and human islets/¿-cells. The research is innovative because it tests novel concepts in physiological and pharmacological regulation of KATP channel trafficking in ¿-cells using unique tools and knowledge developed by our lab for these channels. The research is significant from both human health and basic science standpoints. It will identify new chemical compounds that can correct channel trafficking defects caused by disease mutations, thus giving it high translational potential. Moreover, it will reveal novel physiological signaling mechanisms that may be exploited to control KATP channel surface expression, thereby glucose-secretion coupling in patients with insulin secretion disease. PUBLIC HEALTH RELEVANCE: ATP-sensitive potassium (KATP) channels play a key role in regulating insulin secretion and dysfunction of KATP channels causes abnormal insulin secretion in human as seen in diabetes and hyperinsulinism. The goal of this project is to understand how the abundance of channels in the pancreatic ¿-cell membrane is regulated by physiological signals such as leptin and glucose and by pharmacological agents to affect insulin secretion. The research will lead to development of novel therapeutic strategies for diseases caused by channel misregulation.