Comparative Functional Analysis of Rat TGF−β1 and Xenopus laevis TGF−β1 Promoters Suggest Differential Regulations
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- Springer
Abstract
We have carried out a comparative functional analysis of the rat TGF−β1 and Xenopus laevis TGF−β5 promoters across several mammalian and amphibian cell lines. Progressive deletion constructs of both the promoters have been made using a PCR based approach and the basal promoter activities studied in Xenopus tadpole cell line (XTC), Xenopus adult kidney fibroblast cell line (A6), human hepatoma cell line (HepG2), normal rat kidney cell line (NRK), and Chinese hamster ovary cell line (CHO). Data suggests that the basal promoter activity of TGF−β1 is low as compared to TGF−β5 promoter in XTC cells but comparable in A6 cells, while TGF−β5 promoter shows nearly negligible activity as compared to TGF-beta5 promoter in all the tested mammalian cell lines. Moreover, TGF−β5 promoter is found to be repressed in XTC cells on treatment with TGF−β5 protein. Thus, the regulation of TGF−β1 and TGF−β5 promoters is distinct in amphibian and mammalian species. We therefore suggest that contrary to the suggested functional equivalence of TGF−β1 and TGF−β5 proteins, TGF−β1 and TGF−β5 genes have distinct functions in their respective species
