EXPRESSION OF COLLAGEN BINDING INTEGRINS DURING CARDIAC DEVELOPMENT AND HYPERTROPHY

The interaction between components of the extracellular matrix and the cell surface of cardiac myocytes appears to be regulated in part by receptors belonging to the integrin superfamily. The expression of the integrins was investigated at different stages of development of the heart as well as during cardiac hypertrophy. The characterization of the membrane proteins showed that a beta-1-integrin and associated alpha-chains were responsible for the interaction with collagen, laminin, and fibronectin. Immunoprecipitation data indicated that the presence of specific alpha-chains varied with development. These data were correlated with the ability of the isolated myocytes to attach to specific components of the extracellular matrix. The expression of the alpha-1-chain was prominently associated with the recognition of interstitial collagens. The presence of the alpha-1-chain was also associated with stages when collagen synthesis was increased, especially during fetal and neonatal growth and cardiac hypertrophy. Immunohistochemical localization with the antiserum against beta-1-integrin demonstrated its specific localization near the Z lines of cardiac myocytes. The localization both in vitro and in vivo indicated that the beta-1-integrin may play a role in myofibrillogenesis during development. The present immunohistochemical, cell adhesion, and biochemical data clearly indicate that integrins play a major role in the regulation of the interaction between cardiac myocytes and the extracellular matrix during development and disease.