Adrenergic Regulation of HERG Protein

描述(由申请人提供)：离子通道功能的调节在通过改变心肌细胞的兴奋性来控制心率和收缩能力方面起着关键作用。体液介质和受体参与确定对不断变化的心血管需求的通道反应。离子通道的动态节拍调节精确地由自主神经刺激通过第二信使、激酶、G-蛋白质和蛋白质-蛋白质相互作用的复杂相互作用来控制。HERG基因产生的快速激活延迟整流电流(IKR)因其独特的生物物理特性以及与该通道有关的第二信使和蛋白质相互作用的数量不断增加而被唯一地用于细胞/激素信号的综合转导。我们已经开始将α和β肾上腺素能信号通路映射到HERG/IKR的调制。β-肾上腺素能刺激导致一系列复杂的事件，包括cAMP与HERG的直接结合，与AKAP的相互作用，PKA介导的通道磷酸化，以及14-3-3与HERG的结合。因此，HERG的肾上腺素能调节的演变图景正在显现。了解急性和慢性应激适应导致获得性和遗传性心脏病心律失常和猝死的机制将是至关重要的。因此，我们建议通过结合蛋白质生物化学、免疫化学和膜片钳电生理学的多学科方法来探索这些相互作用对异源表达的蛋白质和内源性心脏组织的影响和机制。具体地说，我们的目标是：1.确定14-3-3E和HERG的PKA调节的意义2.检测AKAP靶向HERG通道的PKA。3.研究PKA对HERG蛋白转运的调控作用。

DESCRIPTION (provided by applicant): Regulation of ion channel function plays a pivotal role in controlling heart rate and contractility via changes in cardiac myocyte excitability. Humoral mediators and receptors are involved in determining channel responses to changing cardiovascular demands. The dynamic beat-to-beat regulation of ion channels is precisely controlled by autonomic stimulation through complex interplay of second messengers, kinases, G-proteins, and protein-protein interactions. The rapidly activating delayed rectifier current (IKr) produced by the HERG gene is uniquely qualified for an integrative transduction of cellular/hormonal signals due to its unusual biophysical properties and the growing number of second-messenger and protein interactions ascribed to the channel. We have begun mapping alpha- and beta-adrenergic signaling pathways to modulation of HERG/IKr. Beta-adrenergic stimulation leads to a complex series of events that includes; direct binding of cAMP to HERG, interactions with AKAPs, PKA-mediated phosphorylation of the channel, and binding of 14-3-3 to HERG. Thus, an evolving picture of adrenergic regulation of HERG is emerging. It will be essential to understand the mechanisms by which acute and chronic stress adaptation leads to arrhythmia and sudden death in both acquired and hereditary cardiac disease. Accordingly, we propose to explore the effects and mechanisms of each of these interactions in a multidisciplinary approach combining protein biochemistry, immunochemistry, and patch clamp electrophysiology on heterologously expressed proteins and endogenous cardiac tissue. Specifically, we aim to: 1. Determine the significance of 14-3-3e and PKA regulation of HERG 2. Examine PKA targeting to HERG channels by AKAPs. 3. Examine PKA-mediated control of trafficking of HERG protein.