A functional domain in the heavy chain of scatter factor/hepatocyte growth factor binds the c-Met receptor and induces cell dissociation but not mitogenesis.
We recently found that scatter factor (SF), a cell motility factor with a multimodular structure, is identical to hepatocyte growth factor (HGF), a potent mitogen of various cell types. SF/HGF is the ligand of the c-Met receptor tyrosine kinase. Here we used transient expression of naturally occurring and in vitro mutagenized cDNAs of SF/HGF to delineate the protein domains necessary for biological activity and binding to the c-Met receptor. (i) A single-chain SF/HGF resulting from the destruction of the protease cleavage site between heavy and light chain (Arg-494--> Gln) was largely inactive, indicating that proteolytic cleavage is essential for acquisition of the biologically active conformation. (ii) A SF/HGF splice variant encoding a protein with a 5-amino acid deletion in the first kringle domain was as highly active as the wild-type molecule. (iii) The separately expressed light chain (with serine protease homology) was inactive in all assays tested. (iv) The separate heavy chain as well as a naturally occurring splice variant consisting of the N terminus and the first two kringle domains bound the c-Met receptor, stimulated tyrosine auto-phosphorylation, and induced scattering of epithelial cells but not mitogenesis. These data indicate that a functional domain in the N terminus/first two kringle regions of SF/HGF is sufficient for binding to the Met receptor and that this leads to the activation of the downstream signal cascade involved in the motility response. However, the complete SF/HGF protein seems to be required for mitogenic activity.
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002455:Cell Division; D002465:Cell Movement; D002478:Cells, Cultured; D004247:DNA / Q000235:genetics; D004252:DNA Mutational Analysis; D004285:Dogs; D017228:Hepatocyte Growth Factor / Q000378:metabolism*; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019859:Proto-Oncogene Proteins c-met; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; D017228:Hepatocyte Growth Factor; D004247:DNA; D011505:Protein-Tyrosine Kinases; D019859:Proto-Oncogene Proteins c-met