Temporal changes in intracellular distribution of protein kinase C during differentiation of human leukemia HL60 cells induced by phorbol ester.

Immunocytochemical methods were used to study protein kinase C (PKC) distribution in HL60 cells during the entire course of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced differentiation. After an initial translocation of PKC from cytoplasm to plasma membrane, the enzyme was localized close to the nuclear membrane region at day 1 of TPA treatment. PKC was associated with nuclei at day 2 and with nuclei, cytoplasma and plasma membrane at days 3 and 5. Attachment of cells to substratum (day 2) was accompanied by increased phosphorylation of several nuclear proteins. At day 7, the differentiated cells became detached and PKC in these cells was largely cytoplasmic. In view of the crucial role of PKC in cell differentiation, it is expected that changes in its intracellular localization have physiological significance.