Vinculin, talin, integrin alpha 6 beta 1 and laminin can serve as components of attachment complex mediating contraction force transmission from cardiomyocytes to extracellular matrix

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 card iomyocytes cultured on coverslips or flexible thin silicone rubber substrat a. 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 n on-penetrating cross-linking agent Bis(sulfosuccinimidyl)-suberate and dete cted by immunohistochemical staining with anti-alpha 6, alpha 3, alpha v, o r beta 1 integrin antibodies. Both alpha 6 and beta 1 showed costameric dis tributions, but alpha 3 and alpha v did not. The distribution of laminin af ter cross-linking and extraction also showed a costameric distribution. Whe n anti-integrin beta 1 antibody was added to live cardiomyocytes grown on t he silicone rubber substratum, the transmission of contraction forces was i nhibited. These findings suggest that vinculin, talin, integrin alpha 6 bet a 1 and laminin system can be involved in transmission of contraction force to the extracellular matrix. Cell Motil. Cytoskeleton 42:1-11, 1999. (C) 1 999 Wiley-Liss, Inc.