小电导Ca2+激活K+通道与ryanodine受体功能性偶联的研究

项目名称： 小电导Ca2+激活K+通道与ryanodine受体功能性偶联的研究

项目编号： No.30870909

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 电工技术

项目作者： 章茜

作者单位： 郑州大学

项目金额： 32万元

中文摘要： 小电导Ca2+-激活K+通道（SK channels）参与心肌细胞动作电位复极化构成，调节生理状态下的心脏节律。为探讨RyRs对心脏SK通道功能的影响，我们采用电生理和慢病毒介导的RNAi证明了RyR2-Ca2+释放通道对小鼠心房细胞SK2通道的功能调控。阻断RyR2或抑制SR Ca2+ATPase可抑制心房细胞SK2通道介导的Ca2+激活K+电流幅值（IK,Ca）；激动RyR2则增加IK,Ca 。构建靶向RyR2 siRNA慢病毒载体并感染小鼠心肌细胞，其RyR2敲减可抑制心房细胞IK,Ca 。共聚焦显微镜Ca2+成像表明激动RyR2可增加心房细胞Ca2+瞬变幅值；反之，则减弱Ca2+荧光信号。提示RyR2-Ca2+释放的变化可影响SK通道功能。通过免疫共沉淀实验表明天然小鼠心肌组织存在SK2通道与RyR2的相互作用。我们的研究首次表明RyR2-Ca2+释放通道对心肌SK2通道的重要作用，细胞内RyRs-敏感的Ca2+信号是心肌细胞SK通道的作用机制之一。本研究从理论上阐明了RyRs对心脏SK通道具有功能调控作用，为临床心律失常的防治及药物筛选提供新的靶点，具有重要的意义。

中文关键词： 离子通道；小电导Ca2+-激活K+通道；Ryanodine 受体；RNA干扰；心肌细胞

英文摘要： Small conductance Ca2+-activated K+ channels (SK，KCa2) are one of subfamily of Ca2+-activated K+ channels (KCa ) which are found in both neuronal and nonneuronal tissues. One member of the SK channels,SK2 channel, is important in configuration of action potential（AP）in atrial myocytes , especially during the late phase of the cardiac AP repolarization and regulates the heart rhythm and rate under physiological conditions. Here, we investigated the potential role of RyRs-Ca2+ release channels on SK2 channel in the mouse atrial myocytes using electrophysiology and lentivirus-mediated small interference RNA (siRNA) targeted against RyR2 to cardiaomyocytes. Our finding show that a Ca2+-activated K+ current (IK,Ca ) recorded from mouse cardiac myocytes was significantly blocked by inhibition of RyR2 or the depletion of intracellular Ca2+ stores. In contrast, the IK,Ca was enhanced by caffeine-induced RyR2 Ca2+ release in the atrial cells. Moreover, the mouse cardiomyocytes transduced by lentivirus-mediated siRNA specific to RyR2 show a significant decrease in the IK,Ca . Confocal images indicate that [Ca2+]i transients in the atrial myocytes were reduced by ryadodine, inhibitor of RyR2, suggesting functional roles of RyR2-sensitive Ca2+ release on the activation of the SK2 channel in mouse cardiomyocytes. Finally，the SK2 channel forms complexes with RyR2 in native mouse atria by Co-immunoprecipitation assays. Our data first reveal that RyR2 plays to an important role in the SK2 channel in mouse cardiac myocytes, and the intracellular Ca2+ signal contributes to the mechanisms determining the SK channels in cardiac myocytes. The new insights may have important implications in providing drug targets for the treatment of arrhythmias.

英文关键词： Ion channel ；Small conductance Ca2+-activated K+ channel; RNA Interference; Cardiac myocytes