THE INVOLVEMENT OF PKC IN N-CADHERIN-MEDIATED ADHERENS JUNCTION ASSEMBLY IN CULTURED CARDIOMYOCYTES

Activation of PKC by PMA was shown to promote the separation of chicke n cardiomyocytes from each other in culture. Immunofluorescence staini ng for N-cadherin indicated that PMA, but not its inactive isoform 4 a lpha PMA, induces the separation of cardiomyocytes and of co-cultured Fibroblasts at intercellular junctional regions. The PMA-induced separ ation of cardiomyocytes and of co-cultured fibroblasts was inhibited b y the PKC inhibitor, H-7. Immunoblot analysis further demonstrated tha t both PKC iota and PKC lambda were expressed in the cardiomyocyte cul tures. While PKC lambda was localized to the cell-cell contact areas b etween cardiomyocytes, PKC iota was only detectable in the perinuclear cytoplasm of the co-cultured fibroblasts. The present findings sugges t the involvement of PKC in regulating N-cadherin-mediated adherens ju nction formation in chicken cardiomyocytes. The differential distribut ion of PKC lambda and PKC iota in the cardiomyocytes and in the co-cul tured fibroblasts suggests that different PKC isozymes are involved in regulating the assembly of intercellular junctions in these two cell types. (C) 1996 Academic Press, Inc.