Protein kinase C-delta associates with vimentin intermediate filaments in differentiated HL60 cells.

The subcellular localization of protein kinase C (PKC)-delta was determined in HL60 cells differentiated toward monocytes/macrophages by treatment with TPA. PKC-delta was detected in the nucleus and cytoplasm of differentiated HL60 cells and, more specifically, associated with structures resembling intermediate filaments. Indirect immunostaining revealed that PKC-delta colocalized with vimentin in the cytosol and perinuclear region of these cells. Immunoprecipitation studies showed that PKC-delta was in an active (autophosphorylated) state in differentiated HL60 cells and that vimentin immunoprecipitated from these cells was also phosphorylated. Treatment of HL60 cells with the PKC-specific inhibitor chelerythrine decreased the phosphorylation of vimentin. These data suggest that vimentin is a substrate for PKC-delta and that this PKC isoenzyme may play a specific role in the regulation of shape change and cell adhesion during HL60 differentiation.