Regulation of Calcium-activated Chloride Conductance in Smooth Muscle Vasculature

描述(申请人提供)：钙激活氯离子通道(CLCA)广泛表达于多种细胞，包括上皮细胞、神经细胞、心肌细胞和平滑肌细胞(SMC)。CICA参与了许多重要的细胞功能，如上皮细胞分泌、神经元和心肌的膜兴奋性以及平滑肌血管张力的调节。由于CICA在肺动脉平滑肌细胞(PASMC)中的表达，这些通道可能参与了各种形式的肺动脉高压(PH)的发病机制。本课题组最近的研究为钙调素依赖的蛋白激酶II(CaMKII)和钙依赖的钙调神经磷酸酶(CaN；PP2B)分别通过磷酸化和去磷酸化调控动脉SMC的钙激活氯电流(ICUCA)提供了证据。由于丝氨酸/苏氨酸磷酸酶可以参与CLCA电导的上调，因此可能还有其他磷酸酶参与其活性的上调。在兔肺动脉SMC中，本研究的主要目标是：1)确定CaMKII和CaN在静态和动态细胞内钙水平下调节CICA通道的相对作用：2)确定CaN AA比CaN A具有特异性的结构决定因素(3)对CICA的调节；以及3)研究其他丝氨酸/苏氨酸磷酸酶(PP1/PP2A)可能参与LCI(Ca)的调节-为完成这一任务，将采用多种技术，包括在兔PASMC全细胞膜片钳条件下使用药物抑制蛋白磷酸酶，以确定PP1和PP2A在CICA电导中的相对贡献。这项技术也将被证明是有用的，以确定Can和另一个(S)Ser/Thr磷酸酶是否靶向共同或不同的磷酸化位点来调节心血管疾病(CVD)仍然是美国最大的杀手之一。根据美国心脏协会的数据，2003年，心血管疾病是美国37%以上死亡的根本原因。由于离子通道在调节血管张力方面起着重要的作用，我们希望对离子通道(如CLCA)在心血管系统中的潜在机制的更好的了解将导致新的血管靶点的开发，以改善高血压、中风、心肌心绞痛和脑梗塞等心血管疾病患者的病情。

DESCRIPTION (provided by applicant): Calcium-activated chloride channels (Clca) are widely expressed in numerous cells including epithelial, neuronal, cardiac and smooth muscle cells (SMC). CICa have been implicated in many important cellular functions such as epithelial secretion, membrane excitability in neurons and cardiac muscle as well as regulation of smooth muscle vascular tone. As a result of CICa expression in pulmonary artery smooth muscle cells (PASMC), there is a possibility that these channels may participate in the etiology of various forms of pulmonary hypertension (PH). Recent work by our group has provided evidence for the modulation of calcium-activated chloride currents (Icuca)) through phoshorylation and dephosphorylation by calmodulin- dependent protein kinase II (CaMKII) and Ca2+dependent Calcineurin (CaN; PP2B) respectively in arterial SMC. As a result of the serine/threonine phosphatase CaN involvement in up-regulation of Clca conductance, it is possible that there may be other phophatases contributing in up-regulation their activity as well. In rabbit pulmonary artery SMCs, the major goals of this research project are to: 1) determine the relative role of CaMKII and CaN in the regulation of CICa channels under static and dynamic intracellular calcium levels; 2) determine the structural determinants conferring specificity of CaN Aa over CaN A(3 in the regulation of CICa; and 3) examine the possible involvement of other serine/threonine phosphatases (PP1/PP2A) in the modulation of lCi(ca)- To accomplish this task, a variety of techniques will be implemented, including the use of pharmacological agents to inhibit protein phosphatases under whole-cell patch clamp conditions in rabbit PASMC to determine the relative contribution of PP1 and PP2A in CICa conductance. This technique will also prove to be useful in determining whether CaN and the other(s) ser/thr phosphatases target a common or distinct phosphorylation site to modulate Cardiovascular disease (CVD) remains to be one of the largest killers in the United States. According to the American Heart Association, in 2003 CVD was the underlying cause of death for more than 37% of all deaths in the United States. Since ion channels play an important role in the regulation of vascular tone, it is our hope that a better understanding of the underlying mechanisms of ion channels (like Clca) in the cardiovascular system will lead to novel vascular targets for the development of new drugs to improve the conditions of patients suffering from CVDs such as PH, stroke, myocardial angina and infarctions.