The Transcription Factor STAT6 Mediates Direct Repression of Inflammatory Enhancers and Limits Activation of Alternatively Polarized Macrophages

• Published in: Immunity (Cambridge, Mass.) Mass.), 2018-01, Vol.48 (1), p.75-90.e6
• Main Authors: Czimmerer, Zsolt, Daniel, Bence, Horvath, Attila, Rückerl, Dominik, Nagy, Gergely, Kiss, Mate, Peloquin, Matthew, Budai, Marietta M., Cuaranta-Monroy, Ixchelt, Simandi, Zoltan, Steiner, Laszlo, Nagy, Bela, Poliska, Szilard, Banko, Csaba, Bacso, Zsolt, Schulman, Ira G., Sauer, Sascha, Deleuze, Jean-Francois, Allen, Judith E., Benko, Szilvia, Nagy, Laszlo
• Format: Article
• Language: English
• Subjects: Acetylation; alternative macrophage polarization; Animals; Biochemistry, Molecular Biology; Blotting, Western; Brugia malayi; Cell activation; Cell Line; Chromatin; Cytokines; DNA-directed RNA polymerase; Enhancer Elements, Genetic; Enhancers; Event-related potentials; Flow Cytometry; Gene expression; Gene Expression Regulation; Gene silencing; Genes; Genetics; Genomes; Genomics; IL-1β; IL-4; Immunology; Infections; inflammasome activation; Inflammasomes; Inflammasomes - metabolism; Inflammation; Inflammatory diseases; Interleukin 4; Interleukin-4 - metabolism; Laser Scanning Cytometry; Life Sciences; Lipopolysaccharides; Lipopolysaccharides - pharmacology; macrophage epigenomics; Macrophages; Macrophages - metabolism; Macrophages - physiology; Mice; Mice, Inbred C57BL; NF-κB protein; Polarization; Polymerase Chain Reaction; Pyroptosis; Pyroptosis - genetics; repression; Ribonucleic acid; RNA; RNA polymerase; RNA polymerase II; Signal transduction; Signal Transduction - genetics; Signal Transduction - physiology; Signaling; STAT6; Stat6 protein; STAT6 Transcription Factor - metabolism; transcription; Transcription activation; Transcription factors
• ISSN: 1074-7613; 1097-4180
• DOI: 10.1016/j.immuni.2017.12.010

The molecular basis of signal-dependent transcriptional activation has been extensively studied in macrophage polarization, but our understanding remains limited regarding the molecular determinants of repression. Here we show that IL-4-activated STAT6 transcription factor is required for the direct transcriptional repression of a large number of genes during in vitro and in vivo alternative macrophage polarization. Repression results in decreased lineage-determining transcription factor, p300, and RNA polymerase II binding followed by reduced enhancer RNA expression, H3K27 acetylation, and chromatin accessibility. The repressor function of STAT6 is HDAC3 dependent on a subset of IL-4-repressed genes. In addition, STAT6-repressed enhancers show extensive overlap with the NF-κB p65 cistrome and exhibit decreased responsiveness to lipopolysaccharide after IL-4 stimulus on a subset of genes. As a consequence, macrophages exhibit diminished inflammasome activation, decreased IL-1β production, and pyroptosis. Thus, the IL-4-STAT6 signaling pathway establishes an alternative polarization-specific epigenenomic signature resulting in dampened macrophage responsiveness to inflammatory stimuli. [Display omitted] •IL-4-activated STAT6 acts as a transcriptional repressor in macrophages•IL-4-STAT6-repressed enhancers associate with reduced LDTF and p300 binding•Inflammatory responsiveness of the IL-4-repressed enhancers is attenuated•IL-4 limits the LPS-induced inflammasome activation, IL-1β production, and pyroptosis The molecular bases of repressive transcriptional mechanisms contributing to macrophage polarization are not well understood. Czimmerer et al. show that in alternatively polarized macrophages, IL-4-activated STAT6 represses a large set of enhancers modulating the transcriptional program. STAT6-repressed enhancers are characterized by reduced chromatin accessibility, eRNA expression, LDTF, and p300 binding. IL-4-STAT6-mediated repression limits the inflammatory responsiveness including inflammasome activation, IL-1β production, and pyroptosis. Thus, the IL4-STAT6 pathway establishes an epigenomic signature to selectively repress the macrophage inflammation program.