The Mode of Action of Heparan and Dermatan Sulfates in the Regulation of Hepatocyte Growth Factor/Scatter Factor

Abstract

Hepatocyte growth factor/scatter factor, in addition to binding to its specific signal-transducing receptor, Met, also interacts with both heparan and dermatan sulfates with high affinity. We have investigated the comparative role of these two glycosaminoglycans in the activation of Met by hepatocyte growth factor/scatter factor. Using glycosaminoglycan-deficient CHO pgsA-745 cells we have shown that growth factor activity is critically dependent upon glycosaminoglycans, and that heparan sulfate and dermatan sulfate are equally potent as coreceptors. Cross-linked 1:1 conjugates of growth factor and either heparan or dermatan sulfate do not dimerize under physiological conditions and are biologically active. This implies that a ternary signaling complex with Met forms in vivo. Native Met isolated from CHO pgsA-745 cells shows only very weak intrinsic affinity for heparin in vitro. Also, a heparin-derived hexasaccharide, which is the minimal size for high affinity binding to the growth factor alone, is sufficient to induce biological activity. Together these observations imply that the role of these glycosaminoglycan may be primarily to effect a conformational change in hepatocyte growth factor/ scatter factor, rather than to induce a necessary growth factor dimerization, or to stabilize a ternary complex by additionally interacting with Met.

The Interactions of Hepatocyte Growth Factor/Scatter Factor and Its NK1 and NK2 Variants with Glycosaminoglycans Using a Modified Gel Mobility Shift Assay

“…The AMAC-labeled dp4 was then cross-linked to HGF/SF using a zero cross-linking strategy as described previously by Lyon et al (20). After cross-linking, the sample was applied to a TSK-G4000PW XL (TosoHaas; 7.8 mm ϫ 30 cm) size exclusion HPLC column eluted with 1.5 M NaCl, 10 mM phosphate, pH 7.2, at 0.5 ml/min.…”

“…Studies with covalently cross-linked conjugates of HGF/SF and GAG oligosaccharides (either HS or DS), in a 1:1 stoichiometry, have suggested that such a "monomeric" complex is the minimal Met-activating unit (20). Importantly, it also demonstrates that activation in vivo is likely to involve a ternary complex of GAG⅐HGF/SF⅐Met, in which HGF/SF binds simultaneously to both GAG and Met.…”

“…Although HGF/SF can bind to Met in the absence of GAGs (14 -16), appropriate activation and signaling through Met require their presence as necessary co-receptors (17)(18)(19)(20). As such, HS and DS appear to be equipotent in their activity, which is * The costs of publication of this article were defrayed in part by the payment of page charges.…”

The N-terminal Domain of Hepatocyte Growth Factor Inhibits the Angiogenic Behavior of Endothelial Cells Independently from Binding to the c-met Receptor

“…According to this model, a monomeric receptor remains inactive until the oligomerized ligand binds and oligomerizes the receptor, allowing autophosphorylation of receptor-associated kinases (51). Nevertheless, an increasing number of data suggest that GAGs do not act only by oligomerizing either ligand or receptor and that their role could be to induce the conformational changes in ligand and/or receptor (52,53).…”

Enhanced bacterial virulence through exploitation of host glycosaminoglycans

“…This may help the bacteria to cross endothelial cell layers and to migrate into host tissues. Another example of possible disruption of tissue integrity could be related to the HGF-induced epithelial cell scattering, which may be affected by the interaction of bacterial GAG-binding adhesins with HSPGs and dermatan sulphate PGs, both known to be required for the biological activity of HGF (Lyon et al, 2001).…”