title: An epigenetic mechanism for high, synergistic expression of indoleamine 2,3-dioxygenase 1 (IDO1) by combined treatment with zebularine and IFN-γ: potential therapeutic use in autoimmune diseases.
abstract: IDO1 can be induced by interferon gamma (IFN-γ) in multiple cell types. We have earlier described that the DNA methyltransferase inhibitor zebularine also induces IDO1 in several rat cell clones. We now describe a synergistic induction of IDO1 expression by IFN-γ and zebularine. To elucidate the mechanism of the IDO1 induction we have studied the methylation status in the promoter region of the IDO1 gene from both human monocytic THP-1 cells and H1D2 rat colon cancer cells. Interestingly, the IDO1 promoter is hypermethylated and IFN-γ is shown to induce a significant demethylation. The synergism in effect of zebularine and IFN-γ on IDO1 expression is paralleled by a similar synergistic effect on expression of two other IFN-γ-responsive genes, the transcription factors STAT1 and IRF1 with binding sites in the IDO1 promoter region. The demonstrated synergistic activation of IDO1 expression has implications in relation to therapeutic induction of immunosuppression in autoimmunity and chronic inflammation.
authors.affiliation: The Rausing Laboratory, Division of Neurosurgery, Department of Clinical Sciences, Lund University, Lund, Sweden.
authors.forename: Zhong-Tian
authors.initials: ZT
authors.lastname: Xue
authors.forename: Hans-Olov
authors.initials: HO
authors.lastname: Sjögren
authors.forename: Leif G
authors.initials: LG
authors.lastname: Salford
authors.forename: Bengt
authors.initials: B
authors.lastname: Widegren
mesh_terms: D000818:Animals; D001327:Autoimmune Diseases / Q000235:genetics; D002478:Cells, Cultured; D003562:Cytidine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D019175:DNA Methylation; D004357:Drug Synergism; D044127:Epigenesis, Genetic / Q000235:genetics*; D015870:Gene Expression / Q000187:drug effects*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000096:biosynthesis* / Q000235:genetics; D050856:Interferon Regulatory Factor-1 / Q000096:biosynthesis / Q000235:genetics; D007371:Interferon-gamma / Q000008:administration & dosage*; D011401:Promoter Regions, Genetic; D051381:Rats; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050794:STAT1 Transcription Factor / Q000096:biosynthesis / Q000235:genetics
chemical_list: C494257:IRF1 protein, human; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D050856:Interferon Regulatory Factor-1; D050794:STAT1 Transcription Factor; D003562:Cytidine; C009131:pyrimidin-2-one beta-ribofuranoside; D007371:Interferon-gamma