Functional interaction between cardiac Na channels and KATP channels

摘要 心脏钠通道和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，它们确实有某些共同的特征，例如在更高的水平上表达 间盘与侧膜比较，它们与桥粒蛋白共存。我们的新产品 数据表明，心肌KATP通道与Na通道(以及与Na/K ATPase)相互作用。这 提案将利用创新的超分辨率显微镜技术和膜片钳技术来检查 Na通道和KATP通道之间的相互作用。我们将确定膜亚域，其中 相互作用的发生，负责相互作用的分子机制和功能后果 互动。总的假设是，相互作用在膜区域特别显著，在 ICD，这种相互作用是由Ankyrin-G中的特定结合位点介导的，这种相互作用导致功能 Na通道和KATP通道之间的偶联(通过Na/K ATPase)。在第一个目标中，我们将本地化Na 通道和KATP通道以纳米精度连接到侧膜上的膜亚结构域(例如 T形小管、小窝等)以及在插入盘处的膜亚结构域(例如，杂化粘连 交叉点)。将用siRNA研究Anyrins在靶向这些结构域的通道中的作用 接近了。在第二个目标中，我们将研究相互作用涉及的分子机制，测试 假设Na通道和KATP通道与Anyrins上的相似位点结合。我们还将测试 Na通道和KATP通道相互作用的功能后果。这些研究将显著地 推进我们对Na通道和KATP通道及其在心血管系统中的作用的理解， 更广泛地说，加深了我们对心室肌细胞通道系统如何物理和 功能上的互动。

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.