Cardiac K2P and Kv4 potassium channels

描述（由申请人提供）：我们的长期目标是了解钾（K+）通道如何在健康和疾病的心脏中运作。这种更新的应用侧重于K2P和Kv4通道的调节，这是心脏IKp和Ito电流的关键贡献者。最近，这些通道的蛋白、脂质和药物调节因子被确定，心脏K+通道功能障碍与心律失常之间的关系被进一步阐明，这一建议获得了方向。四个具体目标考虑：什么控制通道的表面表达（目标1）；它们如何在地面被一次调制（目标2）；分离抑制剂和激活剂以描绘天然细胞中通道的作用（目标3）；电生理学、生物化学和电子显微镜的综合利用揭示了调控功能的结构基础（Aim 4）。这项提议利用了经典和新颖的策略，这些策略由于生物技术的最新进展而变得更加强大。

DESCRIPTION (provided by applicant): Our long-term goal is to understand how potassium (K+) channels operate in the heart in health and disease. This application for renewal focuses on regulation of K2P and Kv4 channels, key contributors to cardiac IKp and Ito currents. The proposal gains direction from the last period when protein, lipid and drug regulators of these channels were identified and relationships between cardiac K+ channel dysfunction and arrhythmia were further elucidated. Four specific aims consider: what controls surface expression of the channels (Aim 1); how they are modulated once at the surface (Aim 2); isolation of inhibitors and activators to delineate roles of the channels in native cells (Aim 3); and, the structural basis for regulated function as revealed by combined utilization of electrophysiology, biochemistry and electron microscopy (Aim 4). The proposal exploits classical and novel strategies made more powerful by recent advances in biotechnology. In the last period, studies of channels formed by subunits with 2 P domains moved from identification and cloning to in-depth characterization. Formal names ("K2P channels and KCNK genes") were granted and salient attributes made clear: these are K+ selective "leaks" (active across the physiological voltage range) that open and close (gate) and are strictly-regulated. Control is exerted through regulation of channel number and location (N), open probability (Po) and, unitary current (i). Thus, cytosolic proteins control surface expression; phosphorylation and free fatty acids regulate single-channel gating and rectification; and, external proton, toxins and tissue factors modulate flux. Also revealed were roles for the channels in cardiac (and CNS) function and as targets for anti-ischemic drugs and volatile anesthetics. Similar regulatory events determine function of Kv4 voltage-gated channels we find amenable to structural study. Our motivation is that K2P and Kv4 channels operate in strictly-regulated fashion to influence cardiac activity in health while their altered function can lead to disease. These outcomes result because cardiac function requires K+ channels at the correct locale, abundance, and activity level to meet demand. We seek to study these regulatory events in mechanistic and structural detail. Supporting feasibility and significance are findings in the last period and exciting preliminary data.