The Manner Of P300 Participating In The Activation Of IL-12 P40 Gene Transcription

Cytokines play critical roles in regulating all aspects of immune responses, includinglymphoid development, homeostasis, differentiation, tolerance and memory. Interleukin-12(IL-12) is a heterodimeric cytokine produced by macrophages in response to intracellularpathogens, and provides an obligatory signal for the differentiation of T-helper-1 cells. Itconsists of a heavy chain (p40) and a light chain (p35). Control of IL-12 expression inantigen-presenting cells is a critical event in the pathogenesis of infectious andinflammatory diseases. Transcriptional coactivators such as p300 and CREB-binding protein (CBP) functionas important elements in the transcription factors network, linking individualtransactivators via protein-protein interactions to the basal transcriptional machinery. Manytransfactors recruits the p300/CBP and P/CAF coactivators, which participate in theactivation of target gene transcription. It has been shown that the reversible histoneacetylation/deacetylation modification mediated by p300/HDACs participates in theregulation of IL-12 transcription expression. In this study, we analyzed the manner of p300 participating in the activation of IL-12p40 gene transcription. The results demonstrate that p300 was able to work synergisticallywith the transcription factors C/EBP and c-Fos on activation of IL-12 p40 promoter. Wealso studied the manner of p300 interacting with transfactors C/EBP and c-Fos on IL-12p40 promoer by DNA pull-down assays and co-immunoprecipitation. We observed thatthere is direct interaction between p300 and transfactors C/EBP or c-Fos. Then, weidentified the existence of an interaction of IL-12 p40 promoter with c-Fos and C/EBP.Results presented in this paper indicate that p300 participates in the activation of IL-12 p40gene transcription in a manner of formation of a complex with c-Fos and C/EBP on IL-12p40 promoter. All these original results will be helpful in establishing theoretical bases forthe cure of diseases associated with IL-12.