LOCALIZATION OF PROTEIN-KINASE-C IN PRIMARY CULTURES OF HUMAN KERATINOCYTES IN RELATION TO CELL CONTACT PROTEINS

To investigate the role of protein kinase C (PKC), one of the key factors in cellular signalling, in the integrity of cell contacts, we studied the effects of PKC activation and inhibition on cell-cell and cell-substratum contacts. We localized PKC, actin and two major elements of zonula adhaerens (vinculin, E-cadherin) and focal contacts (vinculin) in primary cultures of normal human keratinocytes (nHEK) by fluorescent analogue cytochemistry. The activity of PKC was influenced by administration of TPA (12-O-tetradecanoylphorbol-13-acetate, a specific PKC activator) acid H-7 [1-(5-isoquinolinesulphonyl)-2-methylpiperazine a PKC inhibitor] for various periods of time. Our results show varying effects of TPA and H-7 on zonula adhaerens and focal contacts, suggesting differences in modulation of both types of adherens junctions by mechanisms partially involving PKC. In addition, TPA treatment of nHEK leads to changes in actin cytoskeletal organization.