Fibroblast Growth Factor-1 Induction of Delayed-Early mRNA Expression in NIH 3T3 Cells Is Prolonged by Heparin Addition

• Published in: Experimental cell research 1997-07, Vol.234 (1), p.139-146
• Main Authors: Donohue, Patrick J., Hsu, Debbie K.W., Guo, Yan, Burgess, Wilson H., Winkles, Jeffrey A.
• Format: Article
• Language: English
• Subjects: 3T3 Cells - drug effects; 3T3 Cells - physiology; Animals; Anticoagulants - pharmacology; Blotting, Northern; DNA - biosynthesis; Drug Synergism; Fibroblast Growth Factor 1 - genetics; Fibroblast Growth Factor 1 - pharmacology; Fibroblast Growth Factor 2 - genetics; Gene Expression - drug effects; Heparin - pharmacology; Mice; RNA, Messenger - analysis; RNA, Messenger - metabolism; Time Factors
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1006/excr.1997.3598

Fibroblast growth factor (FGF)-1, also known as acidic FGF, is a multifunctional heparin-binding protein that is mitogenic for a wide variety of cell types culturedin vitroand a potent angiogenic agentin vivo.These cellular responses are mediated via high-affinity binding to a family of four membrane-spanning tyrosine kinase receptors. FGF-1-stimulated mitogenesis is potentiated by heparin, a sulfated glycosaminoglycan. In this study, we examined the effect of exogenous heparin on FGF-1-inducible gene expression in murine NIH 3T3 cells using both wild-type FGF-1 and FGF-1/glu132, an FGF-1 mutant with a reduced apparent affinity for heparin. The induction levels and temporal expression kinetics of two immediate-early response mRNAs (early growth response gene-1, thrombospondin-1) as well as two delayed-early response mRNAs (proliferin, ornithine decarboxylase) were monitored by Northern blot hybridization analysis. We found that although FGF-1 alone can promote the initial induction of these four mRNAs, heparin coaddition is necessary for prolonged delayed-early mRNA expression. This heparin effect occurs when cells are stimulated with wild-type FGF-1 but not with FGF-1/glu132. Furthermore, FGF-1 and heparin must be added together at the initial time of mitogen stimulation and they must remain present in the cell culture medium for a minimum period of 8 h to promote sustained delayed-early mRNA expression. These findings are consistent with the proposal that heparin promotes a long-term FGF-1:FGFR interaction which is required for sustained delayed-early gene expression and a full mitogenic response.