PROTEIN-KINASE C-DELTA ASSOCIATES WITH VIMENTIN INTERMEDIATE FILAMENTS IN DIFFERENTIATED HL-60 CELLS

The subcellular localization of protein kinase C (PKC)-delta was deter mined in HL60 cells differentiated toward monocytes/macrophages by tre atment with TPA. PKC-delta was detected in the nucleus and cytoplasm o f differentiated HL60 cells and, more specifically, associated with st ructures resembling intermediate filaments. Indirect immunostaining re vealed that PKC-delta colocalized with vimentin in the cytosol and per inuclear region of these cells. Immunoprecipitation studies showed tha t PKC-delta was in an active (autophosphorylated) state in differentia ted HL60 cells and that vimentin immunoprecipitated from these cells w as also phosphorylated. Treatment of HL60 cells with the PKC-specific inhibitor chelerythrine decreased the phosphorylation of vimentin. The se data suggest that vimentin is a substrate for PKC-delta and that th is PKC isoenzyme may play a specific role in the regulation of shape c hange and cell adhesion during HL60 differentiation. (C) 1996 Academic Press, Inc.