Hepatocyte growth factor activates CCAAT enhancer binding protein and cell replication via PI3-kinase pathway.
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.
Cho
Min Kyung
MK
National Research Laboratory (MDT), College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Korea.
Kim
Sang Geon
SG
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
D023081:CCAAT-Binding Factor; D004247:DNA; D004791:Enzyme Inhibitors; D017228:Hepatocyte Growth Factor; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors