Long-Term Regulation of Potassium Channels

描述（由申请人提供）：钾通道控制可兴奋细胞如神经元、平滑肌细胞和心肌细胞的功能。钾通道调节在多种细胞类型的程序性细胞死亡中也很重要。虽然对钾通道的功能和急性调节了解很多，但对钾通道功能的长期控制知之甚少。然而，控制血管平滑肌细胞、心肌细胞和神经元中的钾通道表达可能是控制高血压、减少心律失常和癫痫发作发生率的一种有价值的治疗方法。在这里，我们追求三个目标，专注于我们正在进行的钾通道表达和活性的研究。目的1将确定血管紧张素II （Ang II）如何作用于心肌细胞下调Kv4.3通道的表达。实验将验证Ang II通过NADPH氧化酶产生的活性氧（ROS）来破坏通道信使RNA的3'非翻译区稳定的假设。目的2将确定通过高通量筛选鉴定的蛋白质和化学物质如何刺激Kir2.1活性。由于总通道表达不受影响，实验将重点关注这两种激活剂是否影响通道运输和功能。目的3将确定电压门控钾（Kv）通道活性如何作为细胞凋亡的关键步骤缓慢增加。我们将确定磷酸化是否会触发细胞表面新的同源Kv2.1通道的插入。此外，我们将测试在血管平滑肌和心脏中发现的天然通道是否受到类似的调节。这一建议将揭示新的生理、药理学和病理机制的基本见解，这些机制产生心脏、血管和大脑中钾通道活性的长期调节。

DESCRIPTION (provided by applicant): Potassium channels control the function of excitable cells such as neurons, smooth muscle cells and cardiac myocytes. Potassium channel regulation is also important in programmed cell death in a variety of cell types. Although a great deal is understood about the function and acute modulation of potassium channels, little is known about long-term control of potassium channel function. Yet, manipulating potassium channel expression in vascular smooth muscle cells, cardiac myocytes and neurons could be a valuable therapeutic approach for controlling high blood pressure and reducing the incidence of cardiac arrhythmias and epileptic seizures. Here we pursue three aims focused on our ongoing studies of potassium channel expression and activity. Aim 1 will determine how Angiotensin II (Ang II) acts on cardiac myocytes to downregulate Kv4.3 channel expression. Experiments will test the hypothesis Ang II acts via NADPH oxidase- generated reactive oxygen species (ROS) to destabilize the 3' untranslated region of the channel messenger RNA. Aim 2 will determine how a protein and a chemical identified by high throughput screening stimulate Kir2.1 activity. Since total channel expression is unaffected, experiments will focus on whether these two activators affect channel trafficking and function. Aim 3 will determine how voltage-gated potassium (Kv) channel activity is slowly increased as a critical step in apoptosis. We will determine whether phosphorylation triggers insertion of new homomeric Kv2.1 channels in the cell surface. Furthermore, we will test whether native channels found in vascular smooth muscle and the heart are subject to similar regulation. This proposal will reveal fundamental insights into novel physiological, pharmacological and pathological mechanisms that produce long-term regulation of potassium channel activity in the heart, blood vessels and the brain.