Ascorbate stimulation of PAT cells causes an increase in transcription rates and a decrease in degradation rates of procollagen mRNA.

Procollagen alpha 2 (I) mRNA can be induced congruent to 6-fold in primary avian tendon (PAT) cells on addition of ascorbate to the culture medium. Previously, we have shown that the induction is linear after a 12 h lag and requires a total of 60-72 h to achieve maximum levels. We have now investigated in more detail the changes that have occurred in the metabolism of procollagen mRNA in fully induced cells to account for the observed induction. Ascorbate was found to triple the rate of procollagen gene transcription. In addition, there was a stabilization of the mRNA causing the half-life to increase from 10.5 h to 20 h. The increased stability of the procollagen mRNA, however, did not correlate with its ability to bind to oligo (dT)-cellulose. Since a 3-fold change in transcription rates and a 2-fold increase in half-life would account for the 6-fold overall increase in procollagen mRNA levels, we conclude that these are the primary alterations caused by ascorbate addition that give rise to the specific increase in procollagen mRNA.