Alpha-catenin function in cardiomyocyte adhesion and cytoskeletal organization

 描述（由申请人提供）：人类心脏每天跳动超过100，000次，收缩力对将心肌细胞连接在一起以形成功能性心肌的蛋白质复合物提出了独特的物理和调节要求。心肌细胞之间的机械耦合和化学通讯是通过一种称为闰盘（ICD）的特殊粘附结构完成的。ICD包括分别将肌动蛋白和中间丝细胞骨架连接到质膜的粘附连接和桥粒。ICD的形成需要多种粘附和细胞骨架蛋白，这些蛋白的突变可导致心肌病。然而，很少有人知道这些粘合剂复合物是如何组装或调节，以承受心肌细胞收缩的力量，并保持组织的完整性。确定蛋白质复合物如何在ICD中发挥作用以维持粘附稳态对于理解心脏功能和疾病至关重要。 粘附连接的核心是钙粘蛋白-连环蛋白复合物，其通过α-连环蛋白连接到肌动蛋白细胞骨架。α-Catenin是一种多功能肌动蛋白结合蛋白，定位于心肌细胞中的ICD，小鼠中α-catenin功能的丧失会导致心肌病。然而，α-连环蛋白在心肌细胞中的细胞-细胞粘附中的功能知之甚少。我们推测α-连环蛋白通过偶联肌动蛋白和中间丝与ICD连接复合物来调节心肌细胞间的粘附。在这个提议中，我们试图1）确定肌动球蛋白张力如何调节心肌细胞中粘附连接的组装和组织; 2）确定α T-连环蛋白（一种在心脏中表达的主要未表征的α-连环蛋白）的分子特性如何调节粘附连接的组织和与肌动球蛋白网络的连接; 3）确定α T-连环蛋白如何与肌动蛋白和中间丝细胞骨架连接以调节心肌细胞粘附。我们的工作将开发新的工具，并获得有关心肌细胞中细胞-细胞粘附分子机制的新知识，这反过来将为评估ICD蛋白突变对心脏病理生理学的影响提供基础，并为开发治疗心肌病的新策略提供信息。

 DESCRIPTION (provided by applicant): The human heart beats upwards of 100,000 times a day, and contractile forces place unique physical and regulatory demands on the protein complexes that join cardiomyocytes together to form a functional heart muscle. Mechanical coupling and chemical communication between cardiomyocytes is accomplished through a specialized adhesive structure called the intercalated disc (ICD). The ICD comprises adherens junctions and desmosomes that connect the actin and intermediate filament cytoskeletons, respectively, to the plasma membrane. ICD formation requires multiple adhesion and cytoskeletal proteins, and mutations in these proteins can cause cardiomyopathies. However, little is known about how these adhesive complexes are assembled or regulated to withstand the forces of cardiomyocyte contraction and maintain tissue integrity. Determining how protein complexes function at the ICD to maintain adhesive homeostasis is critical for understanding heart function and disease. The core of the adherens junction is the cadherin-catenin complex, which is connected to the actin cytoskeleton through α-catenin. α-Catenin is multifunctional actin-binding protein that localizes to the ICD in cardiomyocytes, and loss of α-catenin function in mice causes cardiomyopathy. However, α-catenin functions in cell-cell adhesion in cardiomyocytes are poorly understood. We hypothesize that α-catenin regulates cardiomyocyte cell-cell adhesion by coupling actin and intermediate filaments to ICD junctional complexes. In this proposal, we seek to 1) define how actomyosin tension regulates adherens junction assembly and organization in cardiomyocytes; 2) identify how the molecular properties of αT-catenin, a largely uncharacterized α-catenin expressed in the heart, regulate adherens junction organization and linkage to the actomyosin network; and 3) determine how αT-catenin links to actin and intermediate filament cytoskeletons to regulate cardiomyocyte adhesion. Our work will develop new tools and acquire new knowledge about the molecular mechanisms of cell-cell adhesion in cardiomyocytes, which in turn will provide the foundation for assessing the impact of mutations in ICD proteins on cardiac pathophysiology and inform the development of new strategies for the treatment of cardiomyopathies.