title: Hepatocyte growth factor activates CCAAT enhancer binding protein and cell replication via PI3-kinase pathway.
abstract: Hepatocyte growth factor (HGF), a ligand of c-Met receptor, stimulates activation of cellular kinases via phosphatidylinositol 3-kinase (PI3-kinase). CCAAT/enhancer binding protein (C/EBP) controls cell cycle progression. The present study was designed to determine whether HGF activates C/EBP in association with the S-phase entrance for cell replication and whether PI3-kinase contributes to the activation of C/EBP. Treatment of H4IIE cells, a hepatocyte-derived cell line, with HGF increased protein binding to the C/EBP binding site at an early time. Immunodepletion, subcellular fractionation, and confocal microscopic analyses showed that the HGF-induced C/EBP DNA binding activity depended on nuclear translocation of C/EBP beta. Whereas stable transfection of the p110 catalytic subunit of PI3-kinase enhanced HGF-mediated nuclear translocation of C/EBP beta and DNA binding, stable transfection of p85 subunit or chemical inhibition of PI3-kinase completely blocked C/EBP activation. HGF increased luciferase reporter activity in cells transfected with a mammalian cell expression vector containing -1.65 kilobase rGSTA2 promoter comprising C/EBP response element (pGL-1651). Whereas transfection with pCMV500, a control vector, allowed pGL-1651 to respond to HGF, expression of dominant negative mutant C/EBP completely inhibited the ability of HGF to stimulate the reporter gene expression. Flow cytometric analysis showed that HGF caused an increase in the area of S phase with a reciprocal decrease in that of G(1) phase, suggesting that HGF promoted cell cycle progression to S phase. In conclusion, HGF induces nuclear translocation of C/EBP beta via the PI3-kinase pathway and stimulates C/EBP DNA binding and gene transcription and that the PI3-kinase-mediated C/EBP activation by HGF may contribute to cell replication.
authors.affiliation: National Research Laboratory (MDT), College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Korea.
authors.forename: Min Kyung
authors.initials: MK
authors.lastname: Cho
authors.forename: Sang Geon
authors.initials: SG
authors.lastname: Kim
mesh_terms: D001769:Blood; D023081:CCAAT-Binding Factor / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects*; D002458:Cell Fractionation; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D016193:G1 Phase / Q000187:drug effects; D017930:Genes, Reporter; D017228:Hepatocyte Growth Factor / Q000494:pharmacology*; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D016196:S Phase / Q000187:drug effects; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection
chemical_list: D023081:CCAAT-Binding Factor; D004247:DNA; D004791:Enzyme Inhibitors; D017228:Hepatocyte Growth Factor; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors