Engineered mutants of HGF/SF with reduced binding to heparan sulphate proteoglycans, decreased clearance and enhanced activity in vivo

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Item Type:	Article
Title:	Engineered mutants of HGF/SF with reduced binding to heparan sulphate proteoglycans, decreased clearance and enhanced activity in vivo
Creators Name:	Hartmann, G., Prospero, T., Brinkmann, V., Ozcelik, O., Winter, G., Hepple, J., Batley, S., Bladt, F., Sachs, M., Birchmeier, C., Birchmeier, W. and Gherardi, E.
Abstract:	BACKGROUND: Although a number of growth factors bind cell-surface heparan sulphate proteoglycans (HSPGs), the role of this interaction is unclear except for fibroblast growth factor which requires HSPG binding for signalling. Hepatocyte growth factor/scatter factor (HGF/SF) plays important roles in mammalian development and tissue regeneration and acts on target cells through a specific receptor tyrosine kinase encoded by the c-met proto-oncogene. This factor also binds HSPGs with high affinity, but conflicting data have been reported on the role of HSPG binding in HGF/SF signalling. RESULTS: To map the binding sites for HSPG and the Met receptor in HGF/SF, we have engineered a number of HGF/SF mutants in which several clusters of solvent-accessible residues in the hairpin structure of the amino-terminal domain or in kringle 2 have been replaced. Two of the mutants (HP1 and HP2) showed greatly decreased (more than 50-fold) affinity for heparin and HSPGs but retained full mitogenic and motogenic activities on target cells in culture. Furthermore, when compared with wild-type HGF/SF, the HP1 mutant exhibited a delayed clearance from the blood, higher tissue levels and a higher induction of DNA synthesis in normal, adult murine liver. CONCLUSIONS: These results establish the following: the binding sites in HGF/SF for Met and for HSPGs can be dissociated by protein engineering; high-affinity binding of HGF/SF to HSPGs is not essential for signalling; one role of HSPG binding in the HGF/SF system appears to be sequestration and degradation of the growth factor; and HGF/SF mutants with decreased affinity for HSPGs exhibit enhanced activity in vivo.
Keywords:	Binding Sites, Cell Line, DNA Replication, Heparan Sulfate Proteoglycans, Heparin, Hepatocyte Growth Factor, Kringles, Liver, Metabolic Clearance Rate, Molecular Models, Peptide Fragments, Protein Binding, Protein Conformation, Proto-Oncogene Proteins c-met, Recombinant Fusion Proteins, Site-Directed Mutagenesis, Tissue Distribution, Animals, Dogs, Mink, Rats
Source:	Current Biology
ISSN:	0960-9822
Publisher:	Cell Press
Volume:	8
Number:	3
Page Range:	125-134
Date:	29 January 1998
Official Publication:	https://doi.org/10.1016/S0960-9822(98)70059-4
PubMed:	View item in PubMed

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