title: The CDK domain of p21 is a suppressor of IL-1beta-mediated inflammation in activated macrophages.
abstract: Significant morbidity and mortality can be attributed to inflammatory diseases; therefore, a greater understanding of the mechanisms involved in the progression of inflammation is crucial. Here, we demonstrate that p21((WAF1/CIP1)), an established suppressor of cell cycle progression, is a inhibitor of IL-1beta synthesis in macrophages. Mice deficient in p21 (p21(-/-)) display increased susceptibility to endotoxic shock, which is associated with increased serum levels of IL-1beta. Administration of IL-1 receptor antagonist reduces LPS-induced lethality in p21(-/-) mice. Analysis of isolated macrophages, which are one of the central producers of IL-1beta, reveals that deficiency for p21 led to more IL-1beta mRNA and pro-protein synthesis following TLR ligation. The increase in IL-1beta pro-protein is associated with elevated secretion of active IL-1beta by p21(-/-) macrophages. siRNA-mediated knockdown of p21 in human macrophages results in increased IL-1beta secretion as well. A peptide mapping strategy shows that the cyclin-dependent-kinase (CDK)-binding domain of p21 is sufficient to reduce the secretion of IL-1beta by p21(-/-) macrophages. These data suggest a novel role for p21 and specifically for the CDK-binding domain of p21((WAF1/CIP1)) in inhibiting inflammation.
authors.affiliation: Department of Molecular Microbiology and Immunology, School of Medicine, Saint Louis University, Saint Louis, MO, USA.
authors.forename: John C
authors.initials: JC
authors.lastname: Scatizzi
authors.forename: Melissa
authors.initials: M
authors.lastname: Mavers
authors.forename: Jack
authors.initials: J
authors.lastname: Hutcheson
authors.forename: Brittany
authors.initials: B
authors.lastname: Young
authors.forename: Bo
authors.initials: B
authors.lastname: Shi
authors.forename: Richard M
authors.initials: RM
authors.lastname: Pope
authors.forename: Eric M
authors.initials: EM
authors.lastname: Ruderman
authors.forename: Damien S K
authors.initials: DS
authors.lastname: Samways
authors.forename: John A
authors.initials: JA
authors.lastname: Corbett
authors.forename: Terrance M
authors.initials: TM
authors.lastname: Egan
authors.forename: Harris
authors.initials: H
authors.lastname: Perlman
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000276:immunology* / Q000378:metabolism; D053583:Interleukin-1beta / Q000097:blood*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008262:Macrophage Activation / Q000187:drug effects / Q000276:immunology; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009000:Monocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism
chemical_list: C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D018844:Cyclin-Dependent Kinases