Sumoylation of peroxisome proliferator-activated receptor gamma by apoptotic cells prevents lipopolysaccharide-induced NCoR removal from kappaB binding sites mediating transrepression of proinflammatory cytokines.
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.
Jennewein
Carla
C
Institute of Biochemistry I/Zentrum für Arzneimittelforschung, -Entwicklung und -Sicherheit, Faculty of Medicine, Goethe-University Frankfurt am Main, Frankfurt, Germany.
Kuhn
Anne-Marie
AM
Schmidt
Martina Victoria
MV
Meilladec-Jullig
Virginie
V
von Knethen
Andreas
A
Gonzalez
Frank J
FJ
Brüne
Bernhard
B
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*
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