Differential regulation of IL-12 and IL-10 gene expression in macrophages by the basic leucine zipper transcription factor c-Maf fibrosarcoma

S Cao, J Liu, M Chesi, PL Bergsagel, I Ho… - The Journal of …, 2002 - journals.aai.org
S Cao, J Liu, M Chesi, PL Bergsagel, I Ho, RP Donnelly, X Ma
The Journal of Immunology, 2002journals.aai.org
IL-12 is a principal activator of both innate and adaptive immunity against infectious agents
and malignancies. Regulation of proinflammatory IL-12 gene expression in phagocytes by
the anti-inflammatory cytokine IL-10 represents a major homeostatic process underlying host-
pathogen and host-self interactions. Delineation of the signaling pathway of IL-10 is crucial
to the understanding of immunological regulatory networks. In this study, we report that IL-10
and c-musculoaponeurotic fibrosarcoma (Maf) induce their mutual expression in …
Abstract
IL-12 is a principal activator of both innate and adaptive immunity against infectious agents and malignancies. Regulation of proinflammatory IL-12 gene expression in phagocytes by the anti-inflammatory cytokine IL-10 represents a major homeostatic process underlying host-pathogen and host-self interactions. Delineation of the signaling pathway of IL-10 is crucial to the understanding of immunological regulatory networks. In this study, we report that IL-10 and c-musculoaponeurotic fibrosarcoma (Maf) induce their mutual expression in inflammatory macrophages. We demonstrate that c-Maf is one of the physiological mediators of IL-10’s immunosuppressive activities. When overexpressed, c-Maf selectively inhibits transcriptional activation of IL-12 p40 and p35 genes while potently activating IL-10 and IL-4 expression, potentially contributing to the development of a state of anti-inflammation and dichotomy of immunologic polarization. c-Maf induces changes in nuclear DNA-binding activities at multiple sites including the ets, GA-12, NF-κB, C/EBP, and AP-1 elements. Nonetheless, the essential c-Maf-responsive element appears to be located elsewhere. Inhibition of IL-12 p40 gene expression by c-Maf requires the N-terminal transactivation domain, suggesting an indirect mechanism of transcriptional inhibition involving the induction of an unidentified repressor. In c-Maf-deficient murine macrophages, IL-10 production is impaired. However, IL-10-mediated inhibition of IL-12 production remains intact, indicating the existence of alternative mediators in the absence of c-Maf, consistent with the observation that a functional AP-1 is required for this pathway.
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