HDAC3 requirement for the inflammatory gene expression program in macrophages [ChIP_Seq]

Pan-Hdac inhibitors (HDACi) are endowed with a potent anti-inflammatory activity, but the relative role of each of the eleven Hdac proteins sensitive to HDACi to the inflammatory gene expression program is unknown. Using an integrated genomic approach we found that Hdac3-deficient macrophages are unable to activate almost half of the inflammatory gene expression program when stimulated with lipopolysaccharide (LPS). A large part of the activation defect is due to loss of basal and LPS-inducible expression of IFNb, which in basal cells maintains Stat1 protein levels, and after stimulation acts in an autocrine/paracrine manner to promote a secondary wave of Stat1-dependent gene expression. We show that loss of Hdac3-mediated repression of nuclear receptors leads to hyperacetylation of thousands of genomic sites and associated gene derepression. The upregulation of the constitutively expressed prostaglandin endoperoxide synthase, Ptgs1 (Cox-1), has a causative role in the phenotype, since its chemical inhibition reverts the Ifnb activation defect. These data may have relevance for the use of selective Hdac inhibitors as anti-inflammatory agents. Overall design: Chromatin immuno-precipitations of H4 histone pan-acetylation followed by multiparallel sequencing performed in murine bone marrow-derive macrophages. Experiments carried out in untreated cells as well as in cells treated for 4hrs with lipopolysaccharide (LPS), for both HDAC3 +/- (wt) and HDAC3 -/- (KO) mice.