title: Negative regulation of NF-κB p65 activity by serine 536 phosphorylation.
abstract: Nuclear factor κB (NF-κB) is a master regulator of inflammation and cell death. Whereas most of the activity of NF-κB is regulated through the inhibitor of κB (IκB) kinase (IKK)-dependent degradation of IκB, IKK also phosphorylates subunits of NF-κB. We investigated the contribution of the phosphorylation of the NF-κB subunit p65 at the IKK phosphorylation site serine 536 (Ser(536)) in humans, which is thought to be required for the activation and nuclear translocation of NF-κB. Through experiments with knock-in mice (S534A mice) expressing a mutant p65 with an alanine-to-serine substitution at position 534 (the murine homolog of human Ser(536)), we observed increased expression of NF-κB-dependent genes after injection of mice with the inflammatory stimulus lipopolysaccharide (LPS) or exposure to gamma irradiation, and the enhanced gene expression was most pronounced at late time points. Compared to wild-type mice, S534A mice displayed increased mortality after injection with LPS. Increased NF-κB signaling in the S534A mice was at least in part explained by the increased stability of the S534A p65 protein compared to that of the Ser(534)-phosphorylated wild-type protein. Together, our results suggest that Ser(534) phosphorylation of p65 in mice (and, by extension, Ser(536) phosphorylation of human p65) is not required for its nuclear translocation, but instead inhibits NF-κB signaling to prevent deleterious inflammation.
authors.affiliation: Department of Medicine, Columbia University, New York, NY 10032, USA.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Pradère
authors.affiliation: Department of Medicine, Columbia University, New York, NY 10032, USA.
authors.forename: Céline
authors.initials: C
authors.lastname: Hernandez
authors.affiliation: Department of Medicine III, University Hospital RWTH Aachen, 52074 Aachen, Germany.
authors.forename: Christiane
authors.initials: C
authors.lastname: Koppe
authors.affiliation: Biomedical Informatics Shared Resource, Herbert Irving Comprehensive Cancer Center and Department of Biomedical Informatics, Columbia University, New York, NY 10032, USA.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Friedman
authors.affiliation: Department of Medicine III, University Hospital RWTH Aachen, 52074 Aachen, Germany.
authors.forename: Tom
authors.initials: T
authors.lastname: Luedde
authors.affiliation: Department of Medicine, Columbia University, New York, NY 10032, USA. rfs2102@cumc.columbia.edu.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Schwabe
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D007249:Inflammation / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism; D008070:Lipopolysaccharides / Q000633:toxicity; D008822:Mice, Transgenic; D020125:Mutation, Missense; D010766:Phosphorylation / Q000187:drug effects / Q000235:genetics; D012694:Serine / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism*
chemical_list: D008070:Lipopolysaccharides; C498144:Rela protein, mouse; D051996:Transcription Factor RelA; D012694:Serine