Interaction of Na+/K+-ATPase With It's Signaling Partners

洋地黄类药物(强心苷、强心类固醇)对心脏的管理很有价值。 心力衰竭和心律失常。最近的研究表明，Na/K-ATPase具有一种新的 受体的功能除了其已被熟知的泵送功能外，即响应配体样效应 洋地黄化合物，Na/K-ATPase激活蛋白酪氨酸激酶。具体地说，我们已经证明了 Na/K-ATPase直接与Src相互作用形成一个功能性的洋地黄受体，哇巴因可与其结合 受体刺激相关的Src激酶。这反过来会导致蛋白质酪氨酸的增加。 蛋白激酶和脂肪激酶的磷酸化和募集，以形成一个功能信号小体， 将哇巴因信号传输到不同的细胞内隔间。随之而来的是，激活这个 受体还诱导信号小体的内吞作用，这可能终止信号事件或施加 各种细胞内效应。此外，我们最近绘制了或之间的相互作用域 Na/K-ATPase和Src亚基。这些相互作用说明了一种独特的Na/K-ATPase特异性细胞 Src的调控机制。此外，我们已经能够针对识别出的相互作用区域， 并开发了一种CCI特异性多肽，可以破坏Na/K-ATPase/Src受体复合体的形成 并抑制Src活性。该应用程序建立在这些新发现和初步发现的基础上，并且 目的是进一步描述构成Na/K-ATPase/Src形成的分子相互作用 受体复合体，并评估该受体在洋地黄激活的信号转导中的功能。 为了实现这些目标，我们提出了以下三个具体目标。首先，我们将检验这一假设 功能性Na/K-ATPase/Src受体复合体的形成需要一对相互作用，包括 Na/K-ATPase a，A-结构域/Src SH2结构域和a，N-结构域/Src激酶结构域。第二，我们将 开发和使用细胞通透性Na/K-ATPase特异性的Src抑制剂/激活剂来检验这一假设 Na/K-ATPase/Src受体的激活是其药理/信号作用的机制之一 哇巴因在心里。最后，我们将使用转基因动物模型来进一步评估 心脏中Na/K-ATPase/Src受体复合体的功能。这些研究的结果将提供 Na/K-ATPase介导的信号转导与洋地黄分子机制的新认识 药理学。此外，随着对这些新的细胞信号机制的更好理解，新的 制定治疗或预防人类疾病的有效治疗干预措施的目标， 包括心脏功能障碍，可能会被证实。

Digitalis drugs (cardiac glycosides, cardiotonic steroids) have been valuable for the management of heart failure and cardiac arrhythmias. Recent studies have demonstrated that the Na/K-ATPase has a novel receptor function in addition to its well described pumping function; i.e., in response to a ligand-like effect of a digitalis compound, Na/K-ATPase activates protein tyrosine kinases. Specifically, we have shown that Na/K-ATPase directly interacts with Src to form a functional digitalis receptor, and ouabain binding to this receptor stimulates the associated Src kinase. This, in turn, results in the increased protein tyrosine phosphorylation and recruitment of protein kinases and lipid kinases to form a functional signalosome that transmits the ouabain signal to different intracellular compartments. Concomitantly, activation of this receptor also induces endocytosis of the signalosome which may terminate the signaling events, or exert various intracellular effects. Moreover, we have recently mapped the interaction domains between the or subunit of Na/K-ATPase and Src. These interactions illustrate a unique and Na/K-ATPase-specific cellular mechanism of Src regulation. Furthermore, we have been able to target the identified interacting domains, and have developed a cci-specific peptide that disrupts the formation of Na/K-ATPase/Src receptor complex and inhibits Src activity. This application is built upon these new discoveries and preliminary findings, and is aimed to further delineate the molecular interactions that constitute the formation of the Na/K-ATPase/Src receptor complex, and to evaluate the functionality of this receptor in digitalis-activated signal transduction. To accomplish these goals, we propose the following three Specific Aims. First, we will test the hypothesis that the formation of a functional Na/K-ATPase/Src receptor complex requires a pair of interactions involving the Na/K-ATPase a, A-domain/Src SH2 domain, and the a, N-domain/Src kinase domain. Second, we will develop and employ cell permeable Na/K-ATPase-specific Src inhibitors/activators to test the hypothesis that activation of the Na/K-ATPase/Src receptor is responsible for the pharmacological/signaling actions of ouabain in the heart. Finally, we will employ genetically modified animal models to further evaluate the functionality of the Na/K-ATPase/Src receptor complex in the heart. The results of these studies will provide new insights into the molecular mechanism of Na/K-ATPase-mediated signal transduction and digitalis pharmacology. Moreover, with a better understanding of these new cellular signaling mechanisms, new targets for developing effective therapeutic interventions for the treatment or prevention of human diseases, including cardiac dysfunctions, may be established.