Differential Redistribution of Protein Kinase C Isoforms by Cyclic AMP in HL60 Cells

Abstract

In this study we have analyzed the distribution of protein kinase C isoforms in cytosol, membrane, and nucleus in HL60 cells. Furthermore, we have studied the redistribution of these isoforms after cyclic AMP treatment. Protein kinase C localization and cyclic AMP-induced translocation was demonstrated by Western blot analysis. Cytosol, membrane and nucleus in HL60 cells expressed the abundance of protein kinase C α, βI, βII, δ, λ, and ζ isoforms. After cyclic AMP treatment, the amount of protein kinase C βI and ζ increased only in the nucleus, while protein kinase C δ increased in the three fractions tested. These effects were dependent on the cyclic AMP concentration and duration of action. Our results suggest the existence of cross-talk between the cyclic AMP system and protein kinase C in HL60 cells. Taking into account the processes regulated by protein kinase C, these findings also suggest that cyclic AMP plays a regulatory role in various cellular responses in HL60 cells, such as differentiation and gene expression. The increase observed in PKC δ was due to cyclic AMP-dependent protein kinase C activation, and the synthesis of enzyme was probably activated by the nucleotide.