Functions of Na+/K+ ATPase in cardiac caveolae

描述（由申请人提供）： 这项研究的长期目标是促使重新评估 强心苷在心力衰竭治疗中的应用 这些药物对心脏生长相关基因的调节作用值得赞赏， 对心脏生长的潜在影响。当前的目标是表征信号 转导途径，导致这些基因调控作用，并被激活的 强心苷与心肌肌膜Na+/K+-ATP酶的相互作用。具体 这里提出的研究旨在确定一个专门的Na+/K+池的作用， ATP酶，位于肌膜小窝微域内，在启动这些 信号事件，以及这种酶作为离子泵的经典功能。实验 具体目标1是建立Na亚基和相关的正态分布， 信号蛋白;例如，Src和表皮生长因子受体（EGFR），在小窝中 微区和其他细胞区室，通过无洗涤剂和非变性 分离程序，从培养的大鼠心肌细胞和成年大鼠心脏 心室具体目标2的研究旨在验证我们的假设， 心脏糖苷复合体Na ~+/K ~+-ATP酶信号转导的初步研究 通过调节Src、EGFR和相关信号蛋白的运输来实现转导功能 细胞膜和细胞质之间的间隙。第三章具体目标的研究 验证了这一假设，即与小窝Na+/K+-ATP酶的特殊作用保持一致， 胞膜Na ~+/K ~+-ATP酶的信号转导、离子泵和催化活性 也不同于那些在散装质膜的酶。这些研究将阐明 Na作为能量转换离子泵的双重作用如何控制心脏功能 和调节邻近蛋白质和酶的信号转导蛋白复合物， 与有组织的细胞内信号级联，收缩机制， 线粒体和细胞核。

DESCRIPTION (provided by applicant): The long-term objective of this research is to prompt the reassessment of the risk/benefit ratio of the use of cardiac glycosides for the treatment of heart failure in the light of the newly appreciated effects of these drugs on the regulation of cardiac growth-related genes and their potential effects on cardiac growth. The immediate goal is to characterize the signal transducing pathways that lead to these gene regulatory effects and are activated by the interaction of a cardiac glycoside with the cardiac sarcolemmal Na+/K+-ATPase. The specific studies proposed here are designed to determine the role of a specialized pool of Na+/K+- ATPase that is located within the sarcolemmal caveolae microdomains in the initiation of these signaling events, and in the classical function of this enzyme as an ion pump. Experiments of Specific Aim 1 are designed to establish the normal distributions of Na subunits and related signaling proteins; e.g., Src and epidermal growth factor receptor (EGFR), among caveolae microdomains and other cellular compartments, prepared by detergent-free and nondenaturing fractionation procedures, from cultured rat cardiac myocytes and adult rat heart ventricles. Studies of Specific Aim 2 are designed to test the hypothesis suggested by our preliminary studies that the cardiac glycoside-complexed Na+/K+-ATPase exerts its signal transducing function by regulating the traffics of Src, EGFR, and related signaling proteins between caveolae, the bulk plasma membrane, and the cytosol. Studies of Specific Aim 3 will test the hypothesis that in keeping with the specialized role of caveolar Na+/K+-ATPase in signal transduction, the ion pumping and catalytic activities of the caveolar Na+/K+-ATPase also differ from those of the enzyme in the bulk plasma membrane. These studies will clarify how cardiac function is controlled by Na in its dual roles as an energy transducing ion pump and a signal transducing protein complex that regulates neighboring proteins and enzymes to communicate with the organized intracellular signaling cascades, the contractile machinery, the mitochondria, and the nucleus.