Direct interaction of C/EBPδ and Sp1 at the GC-enriched promoter region synergizes the IL-10 gene transcription in mouse macrophage

Abstract

SummaryWe 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/EBPb and C/EBPd 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/EBPd and Sp1, and also mapped the interaction domains of these two proteins. C/EBPd binds to Sp1 via its basic region leucine zipper domain. The C-terminus of Sp1 was also the major region interacting with C/EBPd. However, both glutamine-and serine/threonine-rich homologus regions of Sp1 also interacted with C/ EBPd. The binding of Sp1 and C/EBPd 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/EBPd 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/ EBPd via a direct interaction between these two transcription factors leading to the activation of the IL-10 gene in mouse macrophage cells.

Role of transcriptional factors Sp1, c-Rel, and c-Jun in LPS-induced C/EBPδ gene expression of mouse macrophages

“…According to the sequence of the downstream Sp1 site, this serves the direct binding site for Sp1, not c-Jun. However, it is known that Sp1 can recruit other transcription factors, e.g., c-Jun [34,35], YY1 [36], NF-kB p65 [37] and C/ EBPd [38], to activate gene expression. In studying the interaction between c-Jun and Sp1, it was reported that the C-terminus of c-Jun is the direct binding domain for Sp1 as shown by in vitro binding assay [39].…”

C/EBPβ and C/EBPδ transcription factors: Basic biology and roles in the CNS

“…C/EBPδ binds to Sp1 via its bZIP domain. Sp1 and C/EBPδ bind as a complex to the Sp1 binding site on the promoter of IL-10 and synergistically activate the transcriptional activity of IL-10 gene in mouse macrophages (Chiang et al 2006). The various modes of interaction between C/EBPs, DNA and other transcription factors are graphically summarized in Figure 7A.…”

Novel Regulators of the Systemic Response to Lipopolysaccharide

“…Different transcription factors regulate the response to LPS in sensitive compared with resistant strains with functional or nonfunctional TLR4. This analysis identified several transcription factors already known to affect the host response to LPS or bacterial infections, including C/EBP (26)(27)(28)(29), transcription factors that bind to the interferon stimulated response element (28,29), Smad3 (30-32), Sp1 (26,33,34), and Stat1 (35,36). Additionally, we identified several potentially novel regulators of the response to systemic LPS in the lung, liver, and spleen, including E2F1, Tead2, Pax4, Cdx-2, Nhlh1, Hoxa4, and HNF4A, among others.…”