HETEROGENEITY OF PROTEIN-KINASE-C ISOFORM EXPRESSION IN CHEMICALLY-INDUCED HL-60 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 γ, β, ε, δ, α, and ζ. In cells treated with phorbol 12-myristate 1 3-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 β, δ, and ζ. 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. © 1993 Academic Press, Inc.