The Role of Vinculin in Cardiomyocyte Adhesion and Mechanical Continuity

项目总结/摘要 心肌细胞每天跳动超过10万次。成功的心脏收缩需要 心肌细胞是物理耦合的。这是通过闰盘（ICD）完成的：a 连接心肌细胞端对端以形成功能性合胞体的专门的粘附结构。的ICD 包含负责机械强度的蛋白质复合物和负责 电导率粘附连接（AJ）是一种负责机械强度的蛋白质复合物 并整合邻近细胞的肌动蛋白细胞骨架。肌原纤维，有组织的肌动蛋白-肌球蛋白结构， 心脏的收缩机制，并产生单个心肌细胞跳动所需的力量。 肌原纤维终止于ICD，连接心肌细胞之间的肌原纤维允许机械连续性 跨细胞然而，这些肌原纤维如何在细胞之间偶联在很大程度上是未知的。 白蛋白是介导细胞-细胞和细胞-细胞外基质（ECM）接触的关键蛋白， 复合物的肌动蛋白细胞骨架。AJ以张力依赖性机制募集到AJ， 在心肌细胞中的AJ-myofibril界面富集。细胞-细胞接触处黏着斑蛋白的表达增加， 老化的心肌，并被认为是心脏保护，和解体的黏着斑蛋白是看到在衰竭的心脏 肌肉.然而，对黏着斑蛋白在ICD中的作用知之甚少。在这项提议中，假设黏着斑蛋白 将肌原纤维锚定到AJs并介导细胞-细胞和细胞-ECM接触之间的串扰。在目标1中， 肌原纤维和AJ之间的连接将通过定义肌原纤维-黏着斑蛋白-AJ界面来研究， 确定黏着斑蛋白及其AJ结合伴侣α E-连环蛋白在促进AJ稳定性中的作用。在目标2中， 将通过改变ECM环境来研究AJs和细胞-ECM接触之间的串扰， 确定其对黏着斑蛋白定位、动力学和细胞-ECM接触和AJs处的张力的影响。 这项工作将进一步了解心脏生物学的一个基本方面： 偶联心肌细胞以产生功能性合胞体。本研究将阐明黏着斑蛋白在 心脏，揭示其心脏保护作用。

Project Summary/Abstract Heart muscle cells (cardiomyocytes) beat over 100,000 times per day. Successful heart contraction requires that cardiomyocytes be physically coupled. This is accomplished through the intercalated disc (ICD): a specialized adhesive structure joining cardiomyocytes end-to-end to form a functional syncytium. The ICD contains protein complexes responsible for mechanical strength and protein complexes responsible for electrical conductance. The adherens junction (AJ) is a protein complex responsible for mechanical strength and integrates the actin cytoskeletons of neighboring cells. Myofibrils, organized actin-myosin structures, are the contractile machinery of the heart and produce the force necessary for individual cardiomyocytes to beat. Myofibrils terminate in the ICD, and linking myofibrils between cardiomyocytes allows for mechanical continuity across cells. However, how these myofibrils are coupled between cells is largely unknown. Vinculin is a key protein mediating cell-cell and cell-extracellular matrix (ECM) contacts, serving to link both complexes to the actin cytoskeleton. Vinculin is recruited to AJs in a tension-dependent mechanism and is enriched at the AJ-myofibril interface in cardiomyocytes. Expression of vinculin at cell-cell contacts increases in aging heart muscle and is thought to be cardio-protective, and disorganization of vinculin is seen in failing heart muscle. Yet the role of vinculin at the ICD is poorly understood. In this proposal, it is hypothesized that vinculin anchors myofibrils to AJs and mediates crosstalk between cell-cell and cell-ECM contacts. In Aim 1, the linkage between myofibrils and AJs will be investigated by defining the myofibril-vinculin-AJ interface and determining the role of vinculin and its AJ binding partner, αE-catenin in promoting AJ stability. In Aim 2, the crosstalk between AJs and cell-ECM contacts will be investigated by altering the ECM environment and determine its influence on vinculin localization, dynamics, and tension at cell-ECM contacts and AJs. The work proposed will further the understanding of a fundamental aspect of cardiac biology: how individual cardiomyocytes are coupled to create a functional syncytium. This research will elucidate vinculin function in the heart, shedding light on to its cardio-protective role.