Fibroblast growth factor-1 induction of delayed-early mRNA expression in NIH 3T3 cells is prolonged by heparin addition.
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 cultured in vitro and a potent angiogenic agent in 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.
Donohue
P J
PJ
Department of Molecular Biology, Holland Laboratory, American Red Cross, Rockville, Maryland 20855, USA.
Hsu
D K
DK
Guo
Y
Y
Burgess
W H
WH
Winkles
J A
JA
D016475:3T3 Cells / Q000187:drug effects / Q000502:physiology; D000818:Animals; D000925:Anticoagulants / Q000494:pharmacology*; D015152:Blotting, Northern; D004247:DNA / Q000096:biosynthesis; D004357:Drug Synergism; D016220:Fibroblast Growth Factor 1 / Q000235:genetics / Q000494:pharmacology*; D016222:Fibroblast Growth Factor 2 / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D006493:Heparin / Q000494:pharmacology*; D051379:Mice; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D013997:Time Factors
D000925:Anticoagulants; D012333:RNA, Messenger; D016222:Fibroblast Growth Factor 2; D016220:Fibroblast Growth Factor 1; D006493:Heparin; D004247:DNA