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

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. and Prospero, T. and Brinkmann, V. and Ozcelik, O. and Winter, G. and Hepple, J. and Batley, S. and Bladt, F. and Sachs, M. and Birchmeier, C. and 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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