Role of vitamin C in basement membrane synthesis and cell differentiation.

thrnunh infprArfinn with thpir nwn rprPnfnr At rpll curfArp (infpnrins). Effects of vitamin C on synthesis and processing of mesenchymal collagens (type I to III) have been well documented. It serves as a cofactor for hydroxylation of proline and lysine residues of collagens. This creates sites (hydroxylysine) for glycosylation and helps the formation of tight inter—chain coiling. It stimulates the transcription of type I collagen gene and stabilizes the mRNAs. It accelerates extracellular processing of procollages by stimulated secretion of collagenase (s). This processing is essential for the bundle formation of collagen. All of these effects support the organization of extracellular matrices of mesenchyme. In this paper, I will present evidence for stimulated synthesis and processing of basement membrane collagen (type IV) by ascorbic acid phosphate (Asc-P). We found that Asc-P accelerated the differentiation of 3T3—L1 fibroblastes into adipocytes. Basement membrane synthesis of endothelial cells and capillary pericytes was also stimulated by Asc-P. The latter effect could explain anti-scorbutic effect of vitamin C. We also analyzed the molecular mechanism of the stimulation of IV collagen synthesis by Aso-P.