Analysis of transcriptional control mechanism for the expression of type I collagen and related gene in fibrotic skin disorders

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Fibrotic skin diseases such as systemic sclerosis(SSc) are characterized by excessive accumulation of collagen in the skin and a variety of internal organs. The accumulation of collagen is thought to result from enhanced transcription of collagen in fibroblasts. Collagen type I, a most abundant protein in the dermis, consists of two α1(I) chain and one α2(I) chain which are coordinately expressed. Co1F1, a DNA binding protein which specifically binds to a segment of the α 2(I)collagen promoter at -400bp upstream of the start of transcription, activates transcription of the α2(I)collagen gene in vitro. We investigated on the partial sequences of polypeptide and the cDNA cloning of this transcriptional factor of the α2(T)collagen gene. The protein purified by sequence-specific DNA affinity chromatography were found to consist of 42kDa and 40.5 kDa polypeptides. Sequences of peptide fragments from 42kDa polypeptide were identical to Purα, which is a nuclear protein which has been reported … More to binds to a upstream region of human c-myc gene. Some of those from 40kDa polypeptide were identical to Purβ, has been partially sequenced and has regions of strong homology to Purα. Full length of Purβ cDNA were sequenced. The deductive amino acid sequences of Purα and Purβ showed 61.4% homology. None of treatment modalities for patients with SSc has brought satisfactory improvement. We, therefore, would like to present effects of the Erythromycin analog EM703 on collagen transcription in normal and scleroderma fibroblasts. EM703 reduced collagen production(to 40% in maximum) and mRNA levels of α1(I) collagen(to 30% in maximum) in a dose dependent manner in normal fibroblasts. EM703 markedly reduced those in all 9 SSc fibroblasts. COL1A1 transcription was down-regulated by 30% in the Luciferase assay. Nuclear extracts from fibroblasts treated with EM703 reduced the CCAAT-binding factor(CBF) binding activity, whereas SP1 binding activity was unchanged. These results suggest that EM703 reduce the type I collagen transcription not only in normal but also in SSc fibroblasts and that the CBF is involved in this reduced expression. Less