title: LPS-Induced G-CSF Expression in Macrophages Is Mediated by ERK2, but Not ERK1.
abstract: Granulocyte colony-stimulating factor (G-CSF) selectively stimulates proliferation and differentiation of neutrophil progenitors which play important roles in host defense against infectious agents. However, persistent G-CSF production often leads to neutrophilia and excessive inflammatory reactions. There is therefore a need to understand the mechanism regulating G-CSF expression. In this study, we showed that U0126, a MEK1/2 inhibitor, decreases lipopolysaccharide (LPS)-stimulated G-CSF promoter activity, mRNA expression and protein secretion. Using short hairpin RNA knockdown, we demonstrated that ERK2, and not ERK1, involves in LPS-induced G-CSF expression, but not LPS-regulated expression of TNF-α. Reporter assays showed that ERK2 and C/EBPβ synergistically activate G-CSF promoter activity. Further chromatin immunoprecipitation (ChIP) assays revealed that U0126 inhibits LPS-induced binding of NF-κB (p50/p65) and C/EBPβ to the G-CSF promoter, but not their nuclear protein levels. Knockdown of ERK2 inhibits LPS-induced accessibility of the G-CSF promoter region to DNase I, suggesting that chromatin remodeling may occur. These findings clarify that ERK2, rather than ERK1, mediates LPS-induced G-CSF expression in macrophages by remodeling chromatin, and stimulates C/EBPβ-dependent activation of the G-CSF promoter. This study provides a potential target for regulating G-CSF expression.
authors.affiliation: Graduate Institute of Medical Sciences, School of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Shwu-Fen
authors.initials: SF
authors.lastname: Chang
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Shih-Shan
authors.initials: SS
authors.lastname: Lin
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Hui-Ching
authors.initials: HC
authors.lastname: Yang
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Yuan-Yi
authors.initials: YY
authors.lastname: Chou
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Jhen-I
authors.initials: JI
authors.lastname: Gao
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Shao-Chun
authors.initials: SC
authors.lastname: Lu
mesh_terms: D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism; D002460:Cell Line; D003851:Deoxyribonucleases / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D016179:Granulocyte Colony-Stimulating Factor / Q000235:genetics*; D008070:Lipopolysaccharides / Q000276:immunology*; D008264:Macrophages / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D047428:Protein Kinase Inhibitors / Q000494:pharmacology
chemical_list: D002070:Butadienes; D022782:CCAAT-Enhancer-Binding Protein-beta; D008070:Lipopolysaccharides; D016328:NF-kappa B; D009570:Nitriles; D047428:Protein Kinase Inhibitors; C113580:U 0126; D016179:Granulocyte Colony-Stimulating Factor; D048049:Extracellular Signal-Regulated MAP Kinases; D019950:Mitogen-Activated Protein Kinase 1; D003851:Deoxyribonucleases