ATP-SENSITIVE POTASSIUM CHANNELS AND INSULIN SECRETION

胰腺ATP敏感性钾通道（KATP通道） 控制B细胞的胰岛素分泌。长期目标是了解 KATP通道在分子水平上被调节以控制胰岛素 分泌物除了受细胞内ATP和ADP的调节外， 特性，其使得通道能够将细胞能量耦合到细胞 兴奋性，调查人员最近表明，该渠道是深刻的 由膜磷酸肌醇调节。磷酸肌醇调节 KATP通道对ATP的敏感性超过几个数量级。这 调节提供了一种机制，以允许通道通过生理学上的 ATP和ADP的浓度。相对于细胞内 核苷酸，我们对磷酸肌醇调节通道的理解是 还处于初期阶段这项研究旨在了解 生理意义和这种新的调节的分子基础 机制为了评估生理意义，研究人员将 操纵胰岛素分泌细胞中的膜磷酸肌醇水平 并检查对通道活性和胰岛素分泌的影响。的 研究人员还将破坏磷酸肌醇之间的相互作用， 通过过度表达缺乏这种能力的突变通道， 与磷酸肌醇相互作用，以及与磷酸肌醇竞争的抑制肽。 磷酸肌醇结合的内源性通道，并评估 生理结果。调查人员将确定 在参与磷酸肌醇调节的通道蛋白中， 系统性定点突变结合电生理学方法 监测通道与通道之间的功能交互的测量， 磷酸肌醇，并与生化测量，监测物理 通道和磷酸肌醇之间的相互作用。到的信息 提出获得对于理解KATP通道调节至关重要， 从而导致胰岛素分泌。它将为新的治疗方法提供见解 胰岛素分泌疾病的方法。

DESCRIPTION: The pancreatic ATP-sensitive potassium channels (KATP channels) control insulin secretion in B-cells. The long-term goal is to understand how KATP channels are regulated at the molecular level to control insulin secretion. In addition to being regulated by intracellular ATP and ADP, a property, which enables the channel to couple, cell energy to cell excitability, the investigators recently showed that the channel is profoundly regulated by membrane phosphoinositides. Phosphoinositides modulate the sensitivity of KATP channels to ATP over several orders of magnitude. This modulation provides a mechanism to allow channels to be gated by physiological concentrations of ATP and ADP. Relative to regulation by intracellular nucleotides, our understanding of channel regulation by phosphoinositides is still in its infancy. The research proposed is aimed at understanding the physiological significance and the molecular basis of this novel regulatory mechanism. To assess the physiological significance, the investigators will manipulate membrane phosphoinositide levels in insulin-secreting cells and-examine the effects on channel activity and insulin secretion. The investigators will also disrupt the interaction between phosphoinositides and channels in these cells by overexpressing mutant channels lacking the ability to interact with phosphoinositides, and inhibitory peptides that compete with endogenous channels for phosphoinositide binding, and evaluate the physiological outcome. The investigators will determine the structural elements within the channel proteins involved in phosphoinositide regulation using systematic site-directed mutagenesis approach combined with electrophysiolgical measurements that monitor functional interaction between the channel and phosphoinositides, and with biochemical measurements that monitor the physical interaction between the channel and phosphoinositides. The information we propose to obtain is crucial for understanding KATP channel regulation and, hence, insulin secretion. It will provide insights to novel therapeutic approaches to diseases of insulin secretion.