Cooperative Interaction between α- and β-Chains of Hepatocyte Growth Factor on c-Met Receptor Confers Ligand-induced Receptor Tyrosine Phosphorylation and Multiple Biological Responses*
- From the Division of Biochemistry, Biomedical Research Center, Osaka University Medical School, Suita, Osaka 565-0871, Japan
Abstract
Hepatocyte growth factor (HGF) is a heterodimeric molecule composed of the α-chain containing the N-terminal hairpin domain, four kringle domains, and the serine protease-like β-chain. We prepared HGF/NK4 and HGF/β from the entire HGF after single-cut digestion with elastase. HGF/NK4 contains the N-terminal hairpin and four kringle domains, while HGF/β is composed of the C-terminal 16 amino acids of the α-chain and the entire β-chain, linked by a disulfide bridge. HGF/NK4 competitively inhibited the binding of125I-HGF to the receptor, and affinity cross-linking analysis indicated that HGF/NK4 alone can bind to the c-Met receptor. In contrast, HGF/β alone did not competitively inhibit the binding of125I-HGF to the receptor and did not bind to the c-Met/HGF receptor. Scatchard analysis and affinity cross-linking experiments indicated that HGF/β specifically binds to c-Met in the presence of HGF/NK4 but not HGF/NK2. Neither HGF/NK4 nor HGF/β alone induced mitogenic, motogenic (cell scattering), and morphogenic (induction of branching tubulogenesis) responses; however, HGF/β did induce these biological responses in the presence of HGF/NK4. Consistent with these results, although neither HGF/NK4 alone nor HGF/β alone induced tyrosine phosphorylation of the c-Met/HGF receptor, HGF/β induced tyrosine phosphorylation of the receptor when c-Met/HGF receptor was occupied by HGF/NK4. These results indicate that HGF/β 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 α- and β-chains, this interaction leading to β-chain-dependent receptor tyrosine phosphorylation and subsequent biological responses.
Footnotes
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↵* This study was supported by a Research Grant for Science and Cancer from the Ministry of Education, Science, Sports, and Culture of Japan, and grants from Sagawa Cancer Research Foundation, the Ryoichi Naito Foundation for Medical Research, Kudo Foundation, and Tanabe Medical Science Foundation.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵‡ To whom correspondence should be addressed. Tel.: 81-6-879-3783; Fax: 81-6-879-3789; E-mail: nakamura{at}onbich.med.osaka-u.ac.jp.
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↵2 K. Matsumoto, H. Kataoka, K. Date, and T. Nakamura, unpublished observation.
- Abbreviations:
- HGF
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hepatocyte growth factor
- TGF-α
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transforming growth factor-α
- PAGE
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polyacrylamide gel electrophoresis
- HPLC
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high performance liquid chromatography
- MDCK
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Madin-Darby canine kidney cells.
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- Received March 9, 1998.
- Revision received June 3, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
