title: Repression of interferon-gamma expression in T cells by Prospero-related homeobox protein.
abstract: Interferon-gamma (IFN-gamma) is a major proinflammatory effector and regulatory cytokine produced by activated T cells and NK cells. IFN-gamma has been shown to play pivotal roles in fundamental immunological processes such as inflammatory reactions, cell-mediated immunity and autoimmunity. A variety of human disorders have now been linked to irregular IFN-gamma expression. In order to achieve proper IFN-gamma-mediated immunological effects, IFN-gamma expression in T cells is subject to both positive and negative regulation. In this study, we report for the first time the negative regulation of IFN-gamma expression by Prospero-related Homeobox (Prox1). In Jurkat T cells and primary human CD4+ T cells, Prox1 expression decreases quickly upon T cell activation, concurrent with a dramatic increase in IFN-gamma expression. Reporter analysis and chromatin immunoprecipitation (ChIP) revealed that Prox1 associates with and inhibits the transcription activity of IFN-,gammapromoter in activated Jurkat T cells. Co-immunoprecipitation and GST pull-down assay demonstrated a direct binding between Prox1 and the nuclear receptor peroxisome proliferator-activated receptor gamma (PPPARgamma, which is also an IFN-gamma repressor in T cells. By introducing deletions and mutations into Prox1, we show that the repression of IFN-gamma promoter by Prox1 is largely dependent upon the physical interaction between Prox1 and PPPARgamma Furthermore, PPPARgammaantagonist treatment removes Prox1 from IFN-gamma promoter and attenuates repression of IFN-gamma expression by Prox1. These findings establish Prox1 as a new negative regulator of IFN-gamma expression in T cells and will aid in the understanding of IFN-gamma transcription regulation mechanisms.
authors.affiliation: State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Linfang
authors.initials: L
authors.lastname: Wang
authors.forename: Jianmei
authors.initials: J
authors.lastname: Zhu
authors.forename: Shifang
authors.initials: S
authors.lastname: Shan
authors.forename: Yi
authors.initials: Y
authors.lastname: Qin
authors.forename: Yuying
authors.initials: Y
authors.lastname: Kong
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.forename: Yuan
authors.initials: Y
authors.lastname: Wang
authors.forename: Youhua
authors.initials: Y
authors.lastname: Xie
mesh_terms: D000813:Anilides / Q000494:pharmacology; D000818:Animals; D016207:Cytokines / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007371:Interferon-gamma / Q000235:genetics / Q000378:metabolism*; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D047495:PPAR gamma / Q000037:antagonists & inhibitors; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000187:drug effects; D025941:Protein Interaction Mapping; D012097:Repressor Proteins / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D000098551:Prospero-Related Homeobox 1 Protein
chemical_list: C457499:2-chloro-5-nitrobenzanilide; D000813:Anilides; D016207:Cytokines; D018398:Homeodomain Proteins; D047495:PPAR gamma; D012097:Repressor Proteins; D025521:Tumor Suppressor Proteins; D000098551:Prospero-Related Homeobox 1 Protein; D007371:Interferon-gamma