Vinculin, talin, integrin α6β1 and laminin can serve as components of attachment complex mediating contraction force transmission from cardiomyocytes to extracellular matrix

Abstract

Recently, we reported that cardiomyocytes adhere to extracellular matrix at costameres, the striated distribution of vinculin between Z-lines and the sarcolemma, where transmission of contraction forces from myofibrils to the extracellular matrix occurs. To identify other molecules involved in force transmission at costameres, we examined adult rat and embryonic chick cardiomyocytes cultured on coverslips or flexible thin silicone rubber substrata. Immunolocalization of talin showed a costameric, striated distribution, which corresponded to dark contacts with interference reflection microscopy. The molecules involved in substrate adhesion were cross-linked with the non-penetrating cross-linking agent Bis(sulfosuccinimidyl)-suberate and detected by immunohistochemical staining with anti-α6, α3, αv, or β1 integrin antibodies. Both α6 and β1 showed costameric distributions, but α3 and αv did not. The distribution of laminin after cross-linking and extraction also showed a costameric distribution. When anti-integrin β1 antibody was added to live cardiomyocytes grown on the silicone rubber substratum, the transmission of contraction forces was inhibited. These findings suggest that vinculin, talin, integrin α6β1 and laminin system can be involved in transmission of contraction force to the extracellular matrix. Cell Motil. Cytoskeleton 42:1–11, 1999. © 1999 Wiley-Liss, Inc.