title: Direct interaction of C/EBPdelta and Sp1 at the GC-enriched promoter region synergizes the IL-10 gene transcription in mouse macrophage.
abstract: We previously reported that LPS activates the transcription of the IL-10 gene through the Sp1 and C/EBP binding sites and indicated that Sp1, C/EBPbeta and C/EBPdelta can coactivate the IL-10 gene expression in mouse macrophage cells [Liu Y.-W., Tseng H.-P., Chen L.-C., Chen B.-K., Chang W.-C. J. Immunol. 171: 821-828, 2003]. In the present report, we demonstrated the direct physical interaction between C/EBPdelta and Sp1, and also mapped the interaction domains of these two proteins. C/EBPdelta binds to Sp1 via its basic region leucine zipper domain. The C-terminus of Sp1 was also the major region interacting with C/EBPdelta. However, both glutamine- and serine/threonine-rich homologus regions of Sp1 also interacted with C/EBPdelta. The binding of Sp1 and C/EBPdelta as a complex to the Sp1 binding site on the promoter of IL-10 was further confirmed by using the DNA affinity precipitation assay. By using Sp1-deficient SL2 cells, we also found that the overexpressions of C/EBPdelta and Sp1 synergically activate the transcriptional activity of IL-10 gene. Taken together, our present results revealed a novel mechanism of a superactivation of Sp1 by C/EBPdelta via a direct interaction between these two transcription factors leading to the activation of the IL-10 gene in mouse macrophage cells.
authors.affiliation: Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, 701, Taiwan.
authors.forename: Ben-Tzu
authors.initials: BT
authors.lastname: Chiang
authors.forename: Yi-Wen
authors.initials: YW
authors.lastname: Liu
authors.forename: Ben-Kuen
authors.initials: BK
authors.lastname: Chen
authors.forename: Ju-Ming
authors.initials: JM
authors.lastname: Wang
authors.forename: Wen-Chang
authors.initials: WC
authors.lastname: Chang
mesh_terms: D000818:Animals; D051743:CCAAT-Enhancer-Binding Protein-delta / Q000378:metabolism*; D020862:GC Rich Sequence; D016753:Interleukin-10 / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D011401:Promoter Regions, Genetic; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D016329:Sp1 Transcription Factor; D016753:Interleukin-10; D051743:CCAAT-Enhancer-Binding Protein-delta