Interleukin-6-induced plasminogen gene expression in murine hepatocytes is mediated by transcription factor CCAAT/enhancer binding protein beta (C/EBPbeta).
An emerging area of research has demonstrated that plasminogen functions in the acute-phase response to tissue injury, neoplastic growth or infection. We have previously shown that the acute-phase mediator, interleukin (IL)-6, increases circulating plasminogen levels via upregulation of plasminogen promoter activity. We also identified a putative IL-6 responsive element (nt -791 to -783; IL6-RE) in the plasminogen gene that is required for maximal stimulation of promoter activity by IL-6. For the present study, we investigated the transcription factors and signaling pathway mediating the response of the plasminogen gene to IL-6. In electrophoretic mobility shift assays (EMSAs), a radiolabeled oligonucleotide IL6-RE probe formed specific complexes with nuclear proteins from untreated hepatocytic cells. The extent of complex formation was markedly increased using nuclear proteins from IL-6-treated cells. Complex formation was abolished by an oligonucleotide with the consensus CCAAT/enhancer binding protein (C/EBP) sequence. Furthermore, complexes were supershifted by antibodies to C/EBPbeta. Treatment of Hepa 1-6 cells with the mitogen-activated protein kinase (MAPK) inhibitor, PD-98059, inhibited IL-6-stimulated plasminogen promoter activity. These results suggest that transcription factor C/EBPbeta and the MAPK pathway play key roles in the response of the plasminogen gene to IL-6, thus elucidating a major mechanism by which the plasminogen system is upregulated to perform its crucial functions in the acute-phase response.
Bannach
F G
FG
Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92103-8411, USA. fbannach@ucsd.edu
Gutierrez-Fernandez
A
A
Parmer
R J
RJ
Miles
L A
LA
D000210:Acute-Phase Reaction; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D022781:Hepatocytes / Q000378:metabolism*; D015850:Interleukin-6 / Q000378:metabolism*; D008156:Luciferases / Q000378:metabolism; D020935:MAP Kinase Signaling System; D051379:Mice; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D010958:Plasminogen / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012689:Sequence Homology, Nucleic Acid; D015398:Signal Transduction; D014158:Transcription, Genetic; D014162:Transfection; D015854:Up-Regulation
D022762:CCAAT-Enhancer-Binding Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D015850:Interleukin-6; D009841:Oligonucleotides; D010958:Plasminogen; D008156:Luciferases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one