Cooperative interaction between alpha- and beta-chains of hepatocyte growth factor on c-Met receptor confers ligand-induced receptor tyrosine phosphorylation and multiple biological responses.
Hepatocyte growth factor (HGF) is a heterodimeric molecule composed of the alpha-chain containing the N-terminal hairpin domain, four kringle domains, and the serine protease-like beta-chain. We prepared HGF/NK4 and HGF/beta from the entire HGF after single-cut digestion with elastase. HGF/NK4 contains the N-terminal hairpin and four kringle domains, while HGF/beta is composed of the C-terminal 16 amino acids of the alpha-chain and the entire beta-chain, linked by a disulfide bridge. HGF/NK4 competitively inhibited the binding of 125I-HGF to the receptor, and affinity cross-linking analysis indicated that HGF/NK4 alone can bind to the c-Met receptor. In contrast, HGF/beta alone did not competitively inhibit the binding of 125I-HGF to the receptor and did not bind to the c-Met/HGF receptor. Scatchard analysis and affinity cross-linking experiments indicated that HGF/beta specifically binds to c-Met in the presence of HGF/NK4 but not HGF/NK2. Neither HGF/NK4 nor HGF/beta alone induced mitogenic, motogenic (cell scattering), and morphogenic (induction of branching tubulogenesis) responses; however, HGF/beta did induce these biological responses in the presence of HGF/NK4. Consistent with these results, although neither HGF/NK4 alone nor HGF/beta alone induced tyrosine phosphorylation of the c-Met/HGF receptor, HGF/beta induced tyrosine phosphorylation of the receptor when c-Met/HGF receptor was occupied by HGF/NK4. These results indicate that HGF/beta binds to the c-Met/HGF receptor that is occupied by HGF/NK4 and induces receptor tyrosine phosphorylation and the subsequent biological activities of HGF. We propose that there exists a unique cooperative interaction between alpha- and beta-chains, this interaction leading to beta-chain-dependent receptor tyrosine phosphorylation and subsequent biological responses.
Division of Biochemistry, Biomedical Research Center, Osaka University Medical School, Suita, Osaka 565-0871, Japan.
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Matsumoto
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Kataoka
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Nakamura
D000345:Affinity Labels; D000818:Animals; D002465:Cell Movement / Q000187:drug effects; D003432:Cross-Linking Reagents; D004285:Dogs; D017228:Hepatocyte Growth Factor / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D008024:Ligands; D009024:Morphogenesis / Q000187:drug effects; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology; D010766:Phosphorylation; D011485:Protein Binding; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism*; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism
D000345:Affinity Labels; D003432:Cross-Linking Reagents; D008024:Ligands; D010446:Peptide Fragments; D014443:Tyrosine; D017228:Hepatocyte Growth Factor; D019859:Proto-Oncogene Proteins c-met