摘要
Objective:To investigate the effect of TGFβ, IFNs and TNFα on promoter activities in mouse α2(I )procollagen gene. Methods: Recombinant constructions PCOL 0. 4, pCOL0. 8, pAZ1009 containing CAT reportergene fused respectively with 400, 800 and 2 000 hp length of the 5'--flanking region in mouse α2(Ⅰ) procollagengene were used for transfection. Promoter activities were determined by CAT reporter gene assay(CAT--ELISA) intransfected cells treated with different cytokines. Results: TGFβ(2 ng/ml ) increased the activities of -- 2kb-- +54hp, -- 780~ + 54hp and -- 348~ +54 hp fragments as promoter respectively, with the increase of activity of 2kb -- + 54hp being most evident. TNFα (100 u/ml ) decreased the activity of -- 2kb ~ + 54hp sequence aspromoter. A slight increase, but not decrease of CAT activities was found in cells treated with IFNα(1000 u/ml)or IFNγ(1 000 u/ml) when pAZ1009 was trans feeted. But CAT expression was decreased more greatly if IFNα orIFNγ was used in combination with TNFα compared with TNFα treatment alone. The same change was seen ifPCOLO. 4 or PCOLO. 8 was used for transfection. Conclusion: Positive TGFβ--responsive elements exist within Zkbflanking region in mouse α2 (Ⅰ ) procollagen gene mediating the fibrogenic effect, while some negative elementsmediate the antifibrotic effect of TNFα. The target antifibrotic effect of IFNs might lie outside this 2kb-- +54bpregion or posttranscriptionally.
