Heparin is required for cell-free binding of basic fibroblast growth factor to a soluble receptor and for mitogenesis in whole cells.
Heparin is required for the binding of basic fibroblast growth factor (bFGF) to high-affinity receptors on cells deficient in cell surface heparan sulfate proteoglycan. So that this heparin requirement could be evaluated in the absence of other cell surface molecules, we designed a simple assay based on a genetically engineered soluble form of murine FGF receptor 1 (mFR1) tagged with placental alkaline phosphatase. Using this assay, we showed that FGF-receptor binding has an absolute requirement for heparin. By using a cytokine-dependent lymphoid cell line engineered to express mFR1, we also showed that FGF-induced mitogenic activity is heparin dependent. Furthermore, we tested a series of small heparin oligosaccharides of defined lengths for their abilities to support bFGF-receptor binding and biologic activity. We found that a heparin oligosaccharide with as few as eight sugar residues is sufficient to support these activities. We also demonstrated that heparin facilitates FGF dimerization, a property that may be important for receptor activation.
Ornitz
D M
DM
Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02115.
Yayon
A
A
Flanagan
J G
JG
Svahn
C M
CM
Levi
E
E
Leder
P
P
D016475:3T3 Cells; D000469:Alkaline Phosphatase / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002455:Cell Division / Q000502:physiology; D002474:Cell-Free System; D004247:DNA; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D006493:Heparin / Q000737:chemistry / Q000502:physiology*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017468:Receptors, Fibroblast Growth Factor; D012995:Solubility
D009844:Oligosaccharides; D011956:Receptors, Cell Surface; D017468:Receptors, Fibroblast Growth Factor; D016222:Fibroblast Growth Factor 2; D006493:Heparin; D004247:DNA; D000469:Alkaline Phosphatase