Bcl-6 and NF-κB cistromes mediate opposing regulation of the innate immune response

GD Barish, TY Ruth, M Karunasiri… - Genes & …, 2010 - genesdev.cshlp.org
GD Barish, TY Ruth, M Karunasiri, CB Ocampo, J Dixon, C Benner, AL Dent, RK Tangirala…
Genes & development, 2010genesdev.cshlp.org
In the macrophage, toll-like receptors (TLRs) are key sensors that trigger signaling cascades
to activate inflammatory programs via the NF-κB gene network. However, the genomic
network targeted by TLR/NF-κB activation and the molecular basis by which it is restrained
to terminate activation and re-establish quiescence is poorly understood. Here, using
chromatin immunoprecipitation sequencing (ChIP-seq), we define the NF-κB cistrome, which
is comprised of 31,070 cis-acting binding sites responsive to lipopolysaccharide (LPS) …
In the macrophage, toll-like receptors (TLRs) are key sensors that trigger signaling cascades to activate inflammatory programs via the NF-κB gene network. However, the genomic network targeted by TLR/NF-κB activation and the molecular basis by which it is restrained to terminate activation and re-establish quiescence is poorly understood. Here, using chromatin immunoprecipitation sequencing (ChIP-seq), we define the NF-κB cistrome, which is comprised of 31,070 cis-acting binding sites responsive to lipopolysaccharide (LPS)-induced signaling. In addition, we demonstrate that the transcriptional repressor B-cell lymphoma 6 (Bcl-6) regulates nearly a third of the Tlr4-regulated transcriptome, and that 90% of the Bcl-6 cistrome is collapsed following Tlr4 activation. Bcl-6-deficient macrophages are acutely hypersensitive to LPS and, using comparative ChIP-seq analyses, we found that the Bcl-6 and NF-κB cistromes intersect, within nucleosomal distance, at nearly half of Bcl-6-binding sites in stimulated macrophages to promote opposing epigenetic modifications of the local chromatin. These results reveal a genomic strategy for controlling the innate immune response in which repressive and inductive cistromes establish a dynamic balance between macrophage quiescence and activation via epigenetically marked cis-regulatory elements.
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