title: Toxoplasma gondii prevents chromatin remodeling initiated by TLR-triggered macrophage activation.
abstract: Macrophages infected with the opportunistic protozoan Toxoplasma gondii are unable to up-regulate many proinflammatory cytokine genes, including TNF (TNF-alpha), upon stimulation with LPS and other TLR ligands. In this study, we examined the influence of T. gondii on transcription factors associated with TNF-alpha transcription, as well as phosphorylation and acetylation of histone H3 at distal and proximal regions of the TNF-alpha promoter. During LPS stimulation, we found that Toxoplasma blocks nuclear accumulation of transcription factor c-Jun, but not that of cAMP response element-binding protein or NF-kappaB. However, chromatin immunoprecipitation studies revealed that binding of all of these transcription factors to the TNF promoter was decreased by T. gondii infection. Furthermore, the parasite blocked LPS-induced Ser(10) phosphorylation and Lys(9)/Lys(14) acetylation of histone H3 molecules associated with distal and proximal regions of the TNF-alpha promoter. Our results show that Toxoplasma inhibits TNF-alpha transcription by interfering with chromatin remodeling events required for transcriptional activation at the TNF promoter, revealing a new mechanism by which a eukaryotic pathogen incapacitates proinflammatory cytokine production during infection.
authors.affiliation: Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Jin
authors.initials: J
authors.lastname: Leng
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Butcher
authors.forename: Charlotte E
authors.initials: CE
authors.lastname: Egan
authors.forename: Delbert S
authors.initials: DS
authors.lastname: Abi Abdallah
authors.forename: Eric Y
authors.initials: EY
authors.lastname: Denkers
mesh_terms: D000107:Acetylation; D000818:Animals; D002478:Cells, Cultured; D042002:Chromatin Assembly and Disassembly / Q000235:genetics / Q000276:immunology*; D017362:Cyclic AMP Response Element-Binding Protein / Q000096:biosynthesis / Q000378:metabolism; D005260:Female; D006657:Histones / Q000037:antagonists & inhibitors / Q000502:physiology; D006801:Humans; D018836:Inflammation Mediators / Q000037:antagonists & inhibitors / Q000502:physiology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008262:Macrophage Activation / Q000235:genetics / Q000276:immunology*; D008264:Macrophages / Q000201:enzymology / Q000276:immunology / Q000469:parasitology; D051379:Mice; D008810:Mice, Inbred C57BL; D010766:Phosphorylation / Q000276:immunology; D011401:Promoter Regions, Genetic / Q000276:immunology; D021381:Protein Transport / Q000235:genetics / Q000276:immunology; D016755:Proto-Oncogene Proteins c-jun / Q000037:antagonists & inhibitors / Q000378:metabolism; D012319:RNA Polymerase II / Q000037:antagonists & inhibitors / Q000378:metabolism; D051193:Toll-Like Receptors / Q000037:antagonists & inhibitors / Q000502:physiology*; D014122:Toxoplasma / Q000276:immunology*; D051996:Transcription Factor RelA / Q000096:biosynthesis / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D006657:Histones; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D016755:Proto-Oncogene Proteins c-jun; D051193:Toll-Like Receptors; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D012319:RNA Polymerase II