title: Sumoylation of peroxisome proliferator-activated receptor gamma by apoptotic cells prevents lipopolysaccharide-induced NCoR removal from kappaB binding sites mediating transrepression of proinflammatory cytokines.
abstract: Efficient clearance of apoptotic cells (AC) by professional phagocytes is crucial for tissue homeostasis and resolution of inflammation. Macrophages respond to AC with an increase in antiinflammatory cytokine production but a diminished release of proinflammatory mediators. Mechanisms to explain attenuated proinflammatory cytokine formation remain elusive. We provide evidence that peroxisome proliferator-activated receptor gamma (PPARgamma) coordinates antiinflammatory responses following its activation by AC. Exposing murine RAW264.7 macrophages to AC before LPS stimulation reduced NF-kappaB transactivation and lowered target gene expression of, that is, TNF-alpha and IL-6 compared with controls. In macrophages overexpressing a dominant negative mutant of PPARgamma, NF-kappaB transactivation in response to LPS was restored, while macrophages from myeloid lineage-specific conditional PPARgamma knockout mice proved that PPARgamma transmitted an antiinflammatory response, which was delivered by AC. Expressing a PPARgamma-Delta aa32-250 deletion mutant, we observed no inhibition of NF-kappaB. Analyzing the PPARgamma domain structures within aa 32-250, we anticipated PPARgamma sumoylation in mediating the antiinflammatory effect in response to AC. Interfering with sumoylation of PPARgamma by mutating the predicted sumoylation site (K77R), or knockdown of the small ubiquitin-like modifier (SUMO) E3 ligase PIAS1 (protein inhibitor of activated STAT1), eliminated the ability of AC to suppress NF-kappaB. Chromatin immunoprecipitation analysis demonstrated that AC prevented the LPS-induced removal of nuclear receptor corepressor (NCoR) from the kappaB site within the TNF-alpha promoter. We conclude that AC induce PPARgamma sumoylation to attenuate the removal of NCoR, thereby blocking transactivation of NF-kappaB. This contributes to an antiinflammatory phenotype shift in macrophages responding to AC by lowering proinflammatory cytokine production.
authors.affiliation: Institute of Biochemistry I/Zentrum für Arzneimittelforschung, -Entwicklung und -Sicherheit, Faculty of Medicine, Goethe-University Frankfurt am Main, Frankfurt, Germany.
authors.forename: Carla
authors.initials: C
authors.lastname: Jennewein
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Kuhn
authors.forename: Martina Victoria
authors.initials: MV
authors.lastname: Schmidt
authors.forename: Virginie
authors.initials: V
authors.lastname: Meilladec-Jullig
authors.forename: Andreas
authors.initials: A
authors.lastname: von Knethen
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Gonzalez
authors.forename: Bernhard
authors.initials: B
authors.lastname: Brüne
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D006801:Humans; D018836:Inflammation Mediators / Q000276:immunology* / Q000378:metabolism; D015850:Interleukin-6 / Q000096:biosynthesis / Q000276:immunology*; D019169:Jurkat Cells; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D016328:NF-kappa B / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D056971:Nuclear Receptor Co-Repressor 1; D047495:PPAR gamma / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D050828:Protein Inhibitors of Activated STAT / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects / Q000276:immunology*; D017434:Protein Structure, Tertiary / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D020218:Response Elements / Q000235:genetics / Q000276:immunology; D025842:SUMO-1 Protein / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D017384:Sequence Deletion / Q000235:genetics / Q000276:immunology; D025841:Small Ubiquitin-Related Modifier Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*
chemical_list: C508600:IL6 protein, human; D018836:Inflammation Mediators; D015850:Interleukin-6; D008070:Lipopolysaccharides; C539127:NCOR1 protein, human; D016328:NF-kappa B; C539128:Ncor1 protein, mouse; D009687:Nuclear Proteins; D056971:Nuclear Receptor Co-Repressor 1; C106529:PIAS1 protein, human; D047495:PPAR gamma; C494211:Pias1 protein, mouse; D050828:Protein Inhibitors of Activated STAT; D012097:Repressor Proteins; D025842:SUMO-1 Protein; D025841:Small Ubiquitin-Related Modifier Proteins; D014409:Tumor Necrosis Factor-alpha