title: Peptidoglycan enhances transcriptional expression of CCAAT/enhancer-binding protein delta gene in mouse macrophages.
abstract: Peptidoglycan-activated gene expression is mediated through various transcription factors including CCAAT/enhancer-binding protein delta (C/EBPdelta). The purpose of the present study is to elucidate the mechanism of PGN-activated C/EBPdelta gene. PGN stimulated C/EBPdelta protein and mRNA expression in mouse macrophages RAW 264.7 cells. Analysis of C/EBPdelta promoter activity by luciferase reporter assay indicated that PGN-induced C/EBPdelta gene activation is partially mediated by the -345 to +24 bp of C/EBPdelta gene promoter. The in vitro protein-DNA binding assay showed that Sp1, c-Rel and c-Jun are the major protein binding to this PGN-response element of C/EBPdelta promoter, and the binding of c-Rel and c-Jun is increased after PGN treatment. All of these binding activities were abolished when Sp1-, NF-kappaB/APRE-, CRE-sites were mutated. Furthermore, analysis of this promoter region by site-directed mutants constructed in luciferase reporter vector indicated that two Sp1-sites, one NF-kappaB/APRE-site and one CRE-site are prominent for PGN-induced gene expression. In addition, when Sp1, c-Rel or c-Jun transcription factors were overexpressed in cells, all of them enhanced C/EBPdelta promoter activity. In summary, we suggest that Sp1, c-Rel and c-Jun transcription factors play important roles in activation of C/EBPdelta gene promoter under the stimulation of PGN. Given the importance of C/EBPdelta in inflammatory disease, these results reveal a clue as a potential therapeutic target for suppression of C/EBPdelta expression under PGN stimulation.
authors.affiliation: Graduate Institute of Biopharmaceutics, College of Life Sciences, National Chiayi University, Chiayi, 600, Taiwan.
authors.forename: Yu-Chiuan
authors.initials: YC
authors.lastname: Huang
authors.forename: Wen-Chang
authors.initials: WC
authors.lastname: Chang
authors.forename: Jyan-Gwo J
authors.initials: JG
authors.lastname: Su
authors.forename: Jheng-Liang
authors.initials: JL
authors.lastname: Cai
authors.forename: Chun-Chia
authors.initials: CC
authors.lastname: Chen
authors.forename: Jan-Jong
authors.initials: JJ
authors.lastname: Hung
authors.forename: Yi-Wen
authors.initials: YW
authors.lastname: Liu
mesh_terms: D000818:Animals; D051743:CCAAT-Enhancer-Binding Protein-delta / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000276:immunology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D010457:Peptidoglycan / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects*; D015533:Transcriptional Activation; D015854:Up-Regulation / Q000235:genetics / Q000276:immunology
chemical_list: D004268:DNA-Binding Proteins; D010457:Peptidoglycan; D014157:Transcription Factors; D051743:CCAAT-Enhancer-Binding Protein-delta