Abstract
The mouse osteoblastic MC3T3-E1 cells were cultured for 7-10 days until subconfluence and then placed in serum-free medium for 24 hours and the cells were subsequently treated with 12-O-tetradecanoylphorbol-13-acetate (TPA ; 100 ng/ml) which enhances protein kinase C activity for 0, 5, 10, 15, 30, and 60 minutes. The c-fos mRNA is rapidly and transiently induced by TPA in mouse osteoblastic MC3T3-E1 cells cultured in both normal medium (control group) and low calcium medium (low Ca group) . The c-fos mRNA expression was seen in both groups, and in both groups, the expression of c-fos mRNA dramatically increased to reach its maximum at 30 minutes after treatment with TPA and was then abolished rapidly (similar to FCS-treated cells1)) . The degree of expression was significantly higher in the low Ca group than in the control group in each treatment period (p<0.01) . This suggests that the MC3T3-E1 cells placed in a low calcium environment react to restore normal cell function at the gene level, mediating activation of protein kinase C (PKC) which plays a role in the induction of c-fos mRNA.
