Ascorbate effects on type I procollagen synthesis by human adult skin fibroblasts: different migration positions of type I procollagen chains on SDS polyacrylamide gel after incubation with ascorbate.

The effects of ascorbate and steroids on type I procollagen synthesis by human skin fibroblasts were studied. Ascorbate treatment (50 micrograms/ml) for 24 hours stimulated a 2-3 fold increase in type I procollagen synthesis and an unexpected shift in the mobility of type I procollagen on SDS polyacrylamide gels. The kinetics of the increase in procollagen synthesis (4 hours) and the shift in electrophoretic mobility (1 hour) were dissimilar, suggesting different controlling mechanisms. This was confirmed by the addition of alpha-alpha'-dipyridyl to ascorbate-treated cultures which eliminated the ascorbate-induced shift in electrophoretic mobility without altering the amount of procollagen synthesis. In contrast, hydrocortisone (1.5 microM) reduced the ascorbate-induced stimulation of type I procollagen synthesis by 80% but did not affect the ascorbate-induced shift in electrophoretic mobility. These studies indicate that the ascorbate-induced increase in type I procollagen synthesis is due to increased levels of type I procollagen mRNA and is independent of the level of hydroxylation of the procollagen.