Spectrin-based signaling complex regulates cardiac excitability

描述（由申请人提供）：正常的心脏兴奋性取决于质膜上特定离子通道和转运体的协调生物物理活性。在过去的十年中，影响离子通道生物物理活性的基因突变与致命的人类心律失常有关。最近，另一类基因突变被发现改变了离子通道与细胞骨架蛋白和调节蛋白的局部偶联。很明显，离子通道的功能取决于正常的生物物理性质和在特定膜域中的适当定位。Ca2+/钙调素依赖性蛋白激酶II （CaMKII）是一种多功能丝氨酸/苏氨酸激酶，具有多种心脏作用，包括调节兴奋收缩、转录和凋亡。最近的研究结果表明，CaMKII在可兴奋细胞内的局部组织对于参与关键细胞功能（如兴奋收缩耦合和长期增强）的离子通道和受体的调节至关重要。我们已经产生了令人兴奋的新的初步数据，确定了CaMKII对心肌细胞嵌入盘的一种新的靶向机制。具体来说，我们已经确定β - lV-spectrin是一种新的嵌入盘状CaMKII锚定蛋白，它可以使CaMKII与心脏中的主要电压门控Na+通道Nav1.5复合物。我们创造了创新的分子、生化和数学工具来验证我们的中心假设，即一种新的基于光谱的嵌入盘状蛋白复合物对于在包括Nav1.5在内的靶蛋白的背景下组织CaMKII至关重要。我们提出以下目标：确定β - lV-spectrin靶向CaMKII至心脏间插盘的分子机制。具体目标2。明确β - lV-spectrin在CaMKII与nav1,5在心脏间插盘的局部组织中的作用。具体目标3。明确spectrin/CaMKII信号复合物在primary的局部调控中的作用

DESCRIPTION (provided by applicant): Normal cardiac excitability depends on the coordinated biophysical activity of specific ion channels and transporters on the plasma membrane. Over the past decade, gene mutations that affect ion channel biophysical activity have been linked with fatal human arrhythmias. Recently, another class of gene mutations has been identified that alters local coupling of ion channels with cytoskeletal and regulatory proteins. It is clear that ion channel function depends on normal biophysical properties AND proper localization within specialized membrane domains. Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a multifunctional serine/threonine kinase with diverse cardiac roles including regulation of excitation contraction, transcription, and apoptosis. Recent findings demonstrate that local organization of CaMKII within excitable cells is essential for regulation of ion channels and receptors involved in critical cell functions such as excitation contraction coupling and long term potentiation. We have generated exciting new preliminary data that identifies a novel targeting mechanism for CaMKII to the cardiomyocyte intercalated disc. Specifically, we have identified beta lV-spectrin as a novel intercalated disc CaMKII anchoring protein that complexes CaMKII with Nav1.5, the primary voltage gated Na+ channel in heart. We have generated innovative molecular, biochemical, and mathematical tools to test our central hypothesis that a novel spectrin-based intercalated disc protein complex is critical for organizing CaMKII in context with target proteins including Nav1.5. We propose the following aims: Specific Aim 1. Determine the molecular mechanism by which beta lV-spectrin targets CaMKII to the cardiac intercalated disc. Specific Aim 2. Define the role of beta lV-spectrin in the local organization of CaMKII with Nav1,5 at the cardiac intercalated disc. Specific Aim 3. Define the role of spectrin/CaMKII signaling complex in the local regulation of primary cardiomyocyte Nav channel function, myocyte electrical activity and arrhythmogenesis.