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

项目摘要 心律失常是心脏电信号中断，导致心脏 以不规则的和不同步的方式跳动。有些心律失常可能是良性的，有些可能是终身的- 威胁，因为心脏用氧气和营养物灌注重要器官的能力严重受损。 暴露了小电导钙激活钾通道（SK通道）由 细胞内钙浓度逐搏增加。SK渠道在 心脏兴奋性的调节和心脏SK通道的功能障碍引起心律失常，包括 心房颤动（AF）。因此，SK通道可能是心律失常治疗的新靶点。 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（PIP 2）是许多质膜结合蛋白的重要调节剂，包括心肌离子 渠道因此，PIP 2可能在心律失常的发生和维持中起关键作用。然而，无论和 PIP 2如何调节心脏SK通道仍然是未知的。我们假设SK通道是 在心肌细胞中由PIP 2调节，PIP 2在SK通道的运输中起关键作用。测试 假设，我们将使用多学科的方法，包括膜片钳，全内反射荧光 （TIRF）显微镜、超分辨率免疫荧光成像、光遗传学和遗传操作。 三个具体的目的是：（1）使用光遗传学技术确定PIP 2对SK通道的调节;（2）使用光遗传学技术确定PIP 2对SK通道的调节。 确定PIP 2调节SK通道的分子机制;（3）检测PIP 2的生理作用 调节心肌细胞。这些研究将揭示心脏SK通道的一种新的调节机制， PIP2。预期的结果将提供新的见解SK通道和PIP 2信号的功能作用 调节心脏兴奋性和心律失常在平移水平，心脏SK通道可以 代表用于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.