PLATELET-DERIVED GROWTH FACTOR-BB STIMULATES SYNTHESIS OF THE INTEGRIN ALPHA(2)-SUBUNIT IN HUMAN-DIPLOID FIBROBLASTS

Platelet-derived growth factor (PDGF)-BB stimulates fibroblast-mediated contraction of collagen gels, as well as migration of fibroblasts through collagen-coated membranes. In the present study we examined effects of PDGF-BB stimulation on the synthesis of collagen-binding beta(1) integrins by human diploid fibroblasts (AG 1518). PDGF-BB stimulation led to an increase in the rate of integrin alpha(2)-subunit synthesis. In contrast, synthesis of the integrin alpha(1)- or alpha(3)-subunits were not affected by PDGF-BB stimulation. Furthermore, levels of alpha(2)-subunit mRNA relative to levels of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA increased after PDGF-BB stimulation. The latter finding is compatible with PDGF-BB stimulating transcription of the alpha(2)-subunit gene. PDGF-BB stimulation did not influence the relation between levels of integrin beta(1)-subunit mRNA and GAPDH mRNA. In addition, the rate of synthesis or post-translational processing of the integrin beta(1)-subunit were not, or only marginally, affected by PDGF-BB stimulation. It is likely that the motility response elicited in fibroblasts by PDGF-BB involves such alterations in the synthesis of the alpha(2)-subunit of the alpha(2) beta(1) collagen-binding integrin. (C) 1994 Academic Press, Inc.