Functional interaction between cardiac Na channels and KATP channels

总结 心脏Na+通道和KATP通道通常被认为在心脏中具有非常不同的作用。 电生理学然而，它们确实具有某些共同的特征，例如在更高的水平上表达， 它们与桥粒蛋白共存。我们的新 数据表明心脏KATP通道与Na+通道（和Na+/K+ ATP酶）相互作用。这 该提案将利用创新的超分辨率显微镜技术和膜片钳来检查 Na+通道和KATP通道之间的相互作用。我们将确定膜子域， 相互作用的发生，负责相互作用的分子机制和相互作用的功能后果， 交互.总的假设是，相互作用是特别突出的膜结构域在 ICD，即相互作用是由特异性结合位点介导的，在锚-G，和相互作用导致功能性 Na+通道和KATP通道之间的偶联（通过Na+/K+ ATP酶）。在第一个目标中，我们将定位Na+ 通道和KATP通道以纳米精度连接到侧膜中的膜子域（例如， t-小管、小窝等）以及在插入盘处的膜子域（例如 junctions）。锚蛋白在靶向这些结构域的通道中的作用将用siRNA进行研究 接近。在第二个目标中，我们将研究相互作用中涉及的分子机制，测试 假设Na+通道和KATP通道结合锚蛋白上的相似位点。我们还将测试 Na+通道和KATP通道相互作用的功能后果。这些研究将大大 进一步了解Na+通道和KATP通道在心血管系统中的作用， 更广泛地说，推进了我们对心室肌细胞中通道系统的物理和 功能性互动。

SUMMARY Cardiac Na+ channels and KATP channels are generally thought to have very different roles in cardiac electrophysiology. They do, however, share certain characteristics such as being expressed at higher levels at the intercalated disk compared to the lateral membranes and they coexist with desmosomal proteins. Our new data demonstrate that cardiac KATP channels interact with Na+ channels (and with the Na+/K+ ATPase). This proposal will utilize innovate super-resolution microscopy techniques and patch clamping to examine the interaction between Na+ channels and KATP channels. We will identify the membrane subdomains where interaction occurs, the molecular mechanisms responsible for interaction and the functional consequences of interactions. The overall hypotheses is that interaction is particularly prominent at membrane domains at the ICD, that interaction is mediated by specific binding sites in ankyrin-G, and that interaction leads to functional coupling between Na+ channels and KATP channels (via the Na+/K+ ATPase). In a first Aim, we will localize Na+ channels and KATP channels with nanometer precision to membrane subdomains in the lateral membrane (e.g. t-tubules, caveolae, etc.) as well as membrane subdomains at the intercalated disk (e.g. hybrid adhering junctions). A role for ankyrins in targeting channels to these domains will be investigated with siRNA approaches. In a second Aim, we will investigate the molecular mechanisms involved in interaction, testing the hypothesis that Na+ channels and KATP channels bind to similar sites on ankyrins. We will also test the functional consequences of interaction of Na+ channels and KATP channels. These studies will significantly move forward our understanding of Na+ channel and KATP channel and function in the cardiovascular system, and more generally, advance our knowledge on how channel systems in ventricular myocytes physically and functionally interact.