Ascorbic acid and transforming growth factor-beta 1 increase collagen biosynthesis via different mechanisms: coordinate regulation of pro alpha 1(I) and Pro alpha 1(III) collagens.
The specific mechanisms of collagen induction in human dermal fibroblasts by ascorbic acid and transforming growth factor-beta 1 (TGF-beta 1) and their effect in combination are uncertain. Collagen synthesis and steady-state levels of pro alpha 1(I) and pro alpha 1(III) collagen RNA were examined in human dermal fibroblasts treated with 100 microM ascorbic acid, 2.5 ng/ml TGF-beta 1, or both. Within 72 h ascorbic acid and TGF-beta 1 had increased collagen synthesis by 2.55 +/- 0.32- and 1.98 +/- 0.13-fold, respectively; in the presence of both, collagen synthesis increased 4.51 +/- 0.74-fold, appearing additive. Ascorbic acid acts specifically by increasing relative collagen synthesis whereas TGF-beta 1 increases overall protein synthesis. Steady-state levels of the pro alpha 1(I) collagen (5.8 and 4.8 kb) and pro alpha 1(III) collagen (5.4 and 4.8 kb) mRNAs were examined independently. Under each condition the steady-state levels of the longer transcripts for pro alpha 1(I) and pro alpha 1(III) collagens appeared coordinately and preferentially elevated. In the presence of both ascorbic acid and TGF-beta 1 the steady-state RNA levels did not increase in an additive manner, suggesting that the additive increase in collagen synthesis results from additional post-transcriptional mechanisms.
Phillips
C L
CL
Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710.
Tajima
S
S
Pinnell
S R
SR
D001205:Ascorbic Acid / Q000494:pharmacology*; D015152:Blotting, Northern; D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007223:Infant; D007700:Kinetics; D008297:Male; D009693:Nucleic Acid Hybridization; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D003094:Collagen; D001205:Ascorbic Acid