Regulation of cardiac small-conductance calcium-activated potassium channels by PIP2

项目总结 心律失常是一种心脏电信号中断的情况，导致心脏 以不规律的、不同步的方式跳动。虽然一些心律失常可能是良性的，但另一些可能是生命- 威胁，因为心脏向重要器官灌流氧气和营养的能力是严重的 妥协了。小电导钙激活钾通道(SK通道)由 在节拍的基础上增加细胞内钙浓度。SK渠道在 心脏兴奋性的调节和心脏SK通道的功能障碍会导致心律失常，包括 房颤(房颤)。因此，SK通道可能是治疗心律失常的新靶点。 心脏SK通道的调节机制已被广泛研究。磷脂酰肌醇4，5- 二磷酸(PIP2)是许多质膜结合蛋白的重要调节因子，包括心脏离子 频道。因此，PIP2可能在心律失常的启动和维持中起关键作用。然而，无论是和 PIP2是如何调节心脏SK通道的，目前尚不清楚。我们假设SK频道是 心肌细胞受PIP2调控，PIP2在SK通道的转运中起关键作用。要测试 假设，我们将使用包括膜片钳、全内反射荧光在内的多学科方法 (TIRF)显微镜、超分辨率免疫荧光成像、光遗传学和遗传操作。 三个具体目标是：(1)利用光遗传学技术确定PIP2对SK通道的调节；(2) 确定PIP2调节SK通道的分子机制；(3)检测PIP2对SK通道的生理影响 心肌细胞的调节。这些研究将揭示心脏SK通道的新的调节机制 PIP2。预期的结果将为SK通道和PIP2信号的功能作用提供新的见解 在心脏兴奋性和心律失常的调节中。在翻译水平上，心脏SK通道可以 代表了治疗心律失常的潜在治疗靶点。

PROJECT SUMMARY Cardiac arrhythmia is a condition where the heart’s electrical signals are disrupted, causing the heart to beat in an irregular and dyssynchronous manner. While some arrhythmias may be benign, others can be life- threatening, as the ability of the heart to perfuse the vital organs with oxygen and nutrients is severely compromised. Small conductance calcium-activated potassium channels (SK channels) are activated by the increase of intracellular calcium concentrations on a beat-to-beat basis. SK channels play critical roles in the regulation of cardiac excitability, and dysfunction of cardiac SK channels causes cardiac arrhythmias including atrial fibrillation (AF). Therefore, SK channel may represent a novel therapeutic target for cardiac arrhythmias. The regulation mechanisms of cardiac SK channels have been extensively studied. Phosphatidylinositol 4,5- bisphosphate (PIP2) is an essential regulator of many plasma membrane-bound proteins, including cardiac ion channels. Hence, PIP2 may play critical roles in arrhythmia initiation and maintenance. However, whether and how cardiac SK channels are regulated by PIP2 are still unknown. We hypothesize that SK channels are regulated by PIP2 in cardiomyocytes and PIP2 plays a critical role in the trafficking of SK channels. To test the hypothesis, we will use multidisciplinary approaches including patch-clamp, total internal reflection fluorescence (TIRF) microscopy, super-resolution immunofluorescence imaging, optogenetics and genetic manipulations. Three specific aims are: (1) determine the regulation of SK channels by PIP2 using optogenetic techniques; (2) determine the molecular mechanisms of PIP2 regulation of SK channels; (3) test the physiological impact of PIP2 regulation in cardiomyocytes. These studies will reveal a new regulatory mechanism of cardiac SK channels by PIP2. The anticipated results will provide novel insights into the functional role of SK channels and PIP2 signaling in the regulation of cardiac excitability and arrhythmia. At the translational level, cardiac SK channels may represent a potential therapeutic target for the treatment of cardiac arrhythmia.