Transforming growth factor-beta increases steady state levels of type I procollagen and fibronectin messenger RNAs posttranscriptionally in cultured human dermal fibroblasts.

Transforming growth factor-jB (TGF,8), when injected subcu- taneously into newborn mice, induces a rapid fibrotic response, stimulates chemotaxis, and elevates the rates of biosynthesis of collagen and fibronectin by fibroblasts in vitro. We explored the molecular mechanisms of TGFft-mediated stimulation of collagen and fibronectin synthesis in cultured human foreskin fibroblasts. TGF,/ preferentially stimulated the synthesis of fibronectin and type I procollagen chains 3-5-fold as shown by polypeptide analysis. Concomitant elevation in the steady state levels of messenger RNAs (mRNAs) coding for type I procollagen and fibronectin also occurred but without a net increase in the rate of transcription of either of these genes. The preferential sta- bilization of mRNAs specifying type I procollagen and fibronectin provides a partial explanation for the mechanisms by which TGFft enhances the synthesis of type I procollagen and fibro- nectin in mesenchymal cells.