Studies on the Differentiation of Skeletal Muscle Cells in uitro : The Phosphorylation and Down Regulation of Protein Kinase C in Myoblasts of Chick Embryos

근세포 분화에 관한 연구 계배의 Myoblasts에 있어서 Protein Kinase C (PKC)의 인 산화작용과 Down Regulation

In the short-term treahent of 12-0-tetradecanoylphorbol-13-acetate (TPA) or platelet-derived growth factor (PDGF), the'Wh and PDGF induced the Protein Kinase C (PKC) activation and migration from the cytoplasm to the peripheral nulcear membrane. And the activated PKC which was directly or indirectly stimulated by TPA or PDGF Phosphorylated many kinds of PKC's targeting proteins and induces various biological responses. Especially, the cytoplasmic PKC was phosphorylated within 1 hr and 10 min by TPA-and PDGF-treahent respectivelv. In the long-term treatment of TPA or PDGF, both of them induced the down-regulation and translocation of PKC in the mvoblasts. The down-regulation of PKC isozyrnes, the pattern of PKC I and ll was similar to the PKC 111 isozpnes in the cytoplasm. But in the nucleolus, the TPA did not induce and down-regulation or the inhibition of the immunoreactivity of PKC III antibody. This investigation indicates that each isozvmes of PKC mal be performed the different effects to the down-regulation of the cytoplasm or nucleolus. And douvn-regulated myoblasts contained low immunoreactivity of PKC antibodies.