A negative feedback loop of ICER and NF-?B regulates TLR signaling in innate immune responses.

ABSTRACT: The NF-?B pathway has important roles in innate immune responses and its regulation is critical to maintain immune homeostasis. Here, we report a newly discovered feedback mechanism for the regulation of this pathway by TLR ligands in macrophages. Lipopolysaccharide (LPS) induced the expression of ICER via p38-mediated activation of CREB in macrophages. ICER, in turn, inhibited the transcriptional activity of NF-?B by direct interaction with the p65 subunit of NF-?B. Deficiency in ICER elevated binding of NF-?B to promoters of pro-inflammatory genes and their subsequent gene expression. Mice deficient in ICER were hypersensitive to LPS-induced endotoxic shock and showed propagated inflammation. Whereas ICER expression in ICER KO bone marrow transplanted mice rescued the ultra-inflammation phenotype, expression of a p65 binding-deficient ICER mutant failed to do so. Our results thus establish p38-CREB-ICER as key components of a negative feedback mechanism necessary to regulate TLR-driven inflammation.

SUBMITTER: Lv S 

PROVIDER: S-EPMC5344209 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature