Objective To investigate the effects of dexamethasone on the promoter activity of human a1(I) procollagen gene. Methods Fibroblasts from human skin were primary cultured and subcultured. (1)The effects of dexamethasone on the human skin fibroblasts were determined by BrdU incorporation into DNA of fibroblasts. (2)Three plasmids containing various lengths of 5’flank sequence of human a1(I) procollagen gene and CAT as reporter gene were constructed, and were transfected into the human skin fibroblasts by FuGENE Transfection Reagent. The effects of dexamethasone on 3 plasmids were determined by CAT－ ELISA. Results (1)After 24h of treatment on the fibroblasts with 110－ 9～ 110－ 4mol/L dexamethasone in DMEM containing 2％ or 10％ FCS, BrdU incorporation into DNA showed no difference (P >0.05). (2) the 3 plasmids were transfected into fibroblasts and then treated with 110－ 5mol/L and 110－ 6mol/L dexamethasones for 24h, relative CAT values were different betwent dexamethasone and control, higher dexamethasone(110－ 5mol/L) and lower dexamethasone(110－ 6mol/L) (P< 0.05). Conclusion Dexamethasone has no effects on the proliferation of human skin fibroblasts, and it has negative effect on the promoter activity of human a1(I) procollagen gene, which is dose－ dependent.
