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 chicken cardiomyocytes from each other in culture. Immunofluorescence staining for N-cadherin indicated that PMA, but not its inactive isoform 4αPMA, induces the separation of cardiomyocytes and of co-cultured fibroblasts at intercellular junctional regions. The PMA-induced separation of cardiomyocytes and of co-cultured fibroblasts was inhibited by the PKC inhibitor, H-7. Immunoblot analysis further demonstrated that both PKCl and PKCλ were expressed in the cardiomyocyte cultures. While PKCλ was localized to the cell-cell contact areas between cardiomyocytes, PKCl was only detectable in the perinuclear cytoplasm of the co-cultured fibroblasts. The present findings suggest the involvement of PKC in regulating N-cadherin-mediated adherens junction formation in chicken cardiomyocytes. The differential distribution of PKCλ and PKCl in the cardiomyocytes and in the co-cultured fibroblasts suggests that different PKC isozymes are involved in regulating the assembly of intercellular junctions in these two cell types.