Direct demonstration of transcriptional activation of collagen gene expression in systemic sclerosis fibroblasts: insensitivity to TGF beta 1 stimulation.

Lesional fibroblasts propagated from the skin of patients with scleroderma, when compared to normal fibroblasts, show increased synthesis of several collagens and increased levels of their corresponding mRNAs. Using constructs (COL1A2/CAT) containing the promoter for the alpha 2 (I) collagen gene in transient transfection assays with matched pairs of scleroderma and normal skin fibroblasts, we observed higher transcriptional activity of the COL1A2 gene in scleroderma fibroblasts and, in contrast to normal fibroblasts, no further expression was observed in the presence of TGF beta 1. Analysis of the expression of COL1A2 promoter deletion constructs indicates that the TGF beta responsive element functional in normal fibroblasts and the sequence involved in intrinsic upregulation of COL1A2 gene expression in scleroderma fibroblasts are both located between bp-376 (Bgl II) and bp-108 (Sma I) sites. These data may indicate that intrinsic upregulation of extracellular matrix genes in scleroderma fibroblasts utilizes a TGF beta dependent pathway.