Heterogeneity of protein kinase C isoform expression in chemically induced HL60 cells

Column chromatographic separation of HL60 cell lysates by hydroxylapatite and immunoblotting with protein kinase C (PKC) isoform-specific antisera revealed the presence of four peaks of activity consisting of PKC gamma, beta, epsilon, delta, alpha, and zeta. In cells treated with phorbol 12-myristate 13-acetate (PMA), 1,25-dihydroxyvitamin D3, retinoic acid, or dimethyl sulfoxide differential changes in the expression of the four peak activities occurred with treatment. During PMA-induced differentiation, PKC activity diminished for peaks 2, 3, and 4 while immunoreactivity increased for beta, delta, and zeta. In addition, all inducers were found to increase the levels of each of the PKC mRNAs. These results document for the first time differential changes in the expression of PKC isoforms in one cell line elicited by different agents and suggest that alterations in substrate preference may occur, which accounts for changes in the activity of PKC.