DISTINCT EFFECTS OF FATTY-ACIDS ON TRANSLOCATION OF GAMMA-SUBSPECIES AND EPSILON-SUBSPECIES OF PROTEIN-KINASE-C

Effects of fatty acids on translocation of the gamma- and epsilon-subs pecies of protein kinase C (PKC) in living cells were investigated usi ng their proteins fused with green fluorescent protein (GFP). gamma-PK C-GFP and epsilon-PKC-GFP predominated in the cytoplasm, but only a sm all amount of gamma-PKC-GFP was found in the nucleus. Except at a high concentration of linoleic acid, all the fatty acids examined induced the translocation of gamma-PKC-GFP from the cytoplasm to the plasma me mbrane within 30 s with a return to the cytoplasm in 3 min, but they h ad no effect on gamma-PKC-GFP in the nucleus. Arachidonic and linoleic acids induced slow translocation of epsilon-PKC-GFP from the cytoplas m to the perinuclear region, whereas the other fatty acids (except for palmitic acid) induced rapid translocation to the plasma membrane. Th e target site of the slower translocation of epsilon-PKC-GFP by arachi donic acid was identified as the Golgi network. The critical concentra tion of fatty acid that induced translocation varied among the 11 fatt y acids tested. In general, a higher concentration was required to ind uce the translocation of epsilon-PKC-GFP than that of gamma-PKC-GFP, t he exceptions being tridecanoic acid, linoleic acid, and arachidonic a cid. Furthermore, arachidonic acid and the diacylglycerol analogue (Di C8) had synergistic effects on the translocation of gamma-PKC-GFP. Sim ultaneous application of arachidonic acid (25 mu M) and DiC8 (10 mu M) elicited a slow, irreversible translocation of gamma-PKC-GFP from the cytoplasm to the plasma membrane after rapid, reversible translocatio n, but a single application of arachidonic acid or DiC8 at the same co ncentration induced no translocation. These findings confirm the invol vement of fatty acids in the translocation of gamma- and epsilon-PKC, and they also indicate that each subspecies has a specific targeting m echanism that depends on the extracellular signals and that a combinat ion of intracellular activators alters the target site of PKCs.