We examine the relationship between the chain length of heparin-derived oligosaccharides, fibroblast growth factor (FGF)-2 binding kinetics and the ability of the oligosaccharides to allow FGF-2-induced proliferation of chlorate-treated rat mammary fibroblasts. First, using an optical biosensor, we show that FGF-2 did not bind disaccharides, but definitively bound to tetrasaccharides. As the chain length increased from tetrasaccharide to octasaccharide, there was a substantial increase in kass (564000M−1·s−1 to 2000000M−1·s−1, respectively) and affinity (Kd 77nM to 11nM, respectively) for FGF-2. From decasaccharides and longer, the kass and affinity for FGF-2 was reduced substantially (tetradecasaccharide kass 470000M−1·s−1, Kd 30nM). In chlorate-treated, and hence sulphated, glycosaminoglycan-deficient cells, FGF-2 alone or in the presence of disaccharides did not stimulate DNA synthesis and it only elicited an early transient dual phosphorylation of p42/44 mitogen-activated protein kinase (MAPK). In the same cells FGF-2 in the presence of tetrasaccharides and longer oligosaccharides was able to restore DNA synthesis and enable the sustained dual phosphorylation of p42/44MAPK. However, the oligosaccharides from tetrasaccharides to octasaccharides were less potent in proliferation assays than deca- and longer oligosaccharides. Therefore, there was no correlation between the binding parameters and the potency of the oligosaccharides in DNA synthesis assays. These results demonstrate that tetrasaccharides are able to bind FGF-2 and enable FGF-2 to stimulate cell proliferation, which sets important boundary conditions for models of the FGF-2—heparan sulphate—FGF receptor complex.
- binding kinetics
- fibroblast growth factor receptor
- heparan sulphate
- optical biosensor
Abbreviations used: dp, degree of polymerization; FGF, fibroblast growth factor; FGFR, FGF receptor; HS, heparan sulphate; MAPK, mitogen-activated protein kinase; p90RSK, ribosomal subunit S6 kinase of 90kDa.
- The Biochemical Society, London ©2002