Contractility dependent regulation of the N‐cadherin complex formation and myocyte structural organization

Cell‐cell coupling via adherens (N‐cadherin) junction plays an important role in cardiac myocyte development, myocardial structure and function. There exists a large gap in the mechanistic understanding of how these varied interactions are regulated. This study investigated the role of alpha‐catenin as a mechanotransducer for N‐cadherin mediated myocyte cytoskeleton assembly. Neonatal ventricular rat myocytes (NVRM) were isolated and plated on N‐cad/ECM adhesive islands of controlled area, anisotropy, and patterned “Y” shape geometry. Contractility was modulated by 2,3‐butanedione 2‐monoxime (BDM), a myosin inhibitor. Radius of curvature was measured as a function of cell contractility and cells were stained and imaged for alpha‐actinin and alpha‐catenin localization as well as f‐actin organization. On N‐cad patterns alpha‐catenin is localized to regions of high internal stress. Inhibition of contractility causes non‐specific localization of alpha‐catenin. Importantly, sarcomere assembly on N‐cadherin is highly disorganized compared to ECM. Paradoxically, sarcomere assembly is promoted by BDM on N‐cad, in counter distinction to that observed on ECM. These results provide evidence for the key role that the alpha‐catenin/cadherin complex plays in myocyte cytoskeleton formation and its importance in electro‐mechanical coupling/remodeling.