Serum regulation of collagen biosynthesis in human diploid fibroblasts.

The mechanism by which serum stimulates collagen production by fibroblasts was examined. Fibroblasts were exposed to various concentrations of serum and collagen production and mRNA levels were measured. Collagen production was determined as collagenase digestible radioactivity and collagen mRNA levels were measured using a [35S]UTP-labelled pro alpha 1[I] probe. The results showed that increased collagen production correlated with enhanced mRNA levels. Extra- and intracellular collagen degradation was similar in control and serum treated cultures, and "G1" and "S" phase fibroblasts contained similar levels of collagen mRNA. We conclude that serum regulation of collagen synthesis occurs primarily at the transcriptional level and that activation of collagen synthesis is not coupled to mitogenic stimulation.