Expression of collagen adhesion proteins and their association with the cytoskeleton in cardiac myocytes

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Abstract
Previous investigations have shown that specific cell surface glycoproteins on rat hepatocytes (COLL‐CAM) are involved in the recognition of interstital collagens (Rubin et al., Exp. Cell Res., 164:127–138, 1986). Western blot analysis with anti‐COLL‐CAM antibodies revealed the presence of a variable but restricted number (two) of glycoproteins in detergent‐extracted membranes from rat hearts at various developmental stages. Using antibodies against these collagen adhesion proteins, we show an expression of the antigens during different developmental stages of the rat heart and during cardiac hypertrophy. This expression is described morphologically by immunohistochemical staining of cell surfaces of freshly isolated myocytes from neonates, normal adults, and hypertrophied adult hearts. Antibodies made against COLL‐CAM were localized on the cell surface of cardiac myocytes and antibodies against talin and vinculin co‐localized in a similar position on the inside of the cell. Antibody staining appears to be increased at times when collagen synthesis is high (neonate and cardiac hypertrophy) and low when collagen synthesis is low, as in the normal adult. These results indicate that collagen adhesion proteins may play an important role in linking the extracellular matrix to the cytoskeleton in the heart.