title: Transcriptional activation of human TR3/nur77 gene expression by human T-lymphotropic virus type I Tax protein through two AP-1-like elements.
abstract: The Tax transactivator of human T-lymphotropic virus type I (HTLV-I) is capable of inducing expression of the human immediate-early TR3/nur77 gene. Deletion and mutation analyses of the TR3/nur77 promoter demonstrated that multiple transcription elements in the 121 bp sequence proximal to the transcription start site are required for full Tax transactivation. Mutations of CArG-like, Ets and RCE motifs in this region severely decreased Tax transactivation. Mutation of either of the two identical AP-1-like elements (NAP 1 and 2) immediately upstream of the TATA box caused around 80% reduction of Tax transactivation. Mutation of both NAP elements blocked Tax-mediated activation totally. These two NAP elements could confer Tax-responsiveness on a heterologous basal promoter. Furthermore, the specific NAP-binding complex was only observed in HTLV-I-infected cells. Formation of this specific NAP-binding complex was correlated directly with Tax expression, as demonstrated in JPX-9 cells upon induction of Tax expression. The specific NAP binding could be competed for by consensus AP-1 and CREB elements, indicating that the NAP-binding proteins probably belong to the AP-1 and CREB/ATF transcription factor families. Supershift analysis with antibodies to both the AP-1 and CREB/ATF transcription factor families revealed that only anti-JunD antibody could partially shift this NAP-binding complex, indicating that JunD is a component of the NAP complex. This work suggests that JunD is involved in Tax-regulated TR3/nur77 expression.
authors.affiliation: Department of Virus and Cancer, Danish Cancer Society, Gustav Wieds Vej 10, DK-8000 Aarhus C, Denmark1.
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Virus and Cancer, Danish Cancer Society, Gustav Wieds Vej 10, DK-8000 Aarhus C, Denmark1.
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Virus and Cancer, Danish Cancer Society, Gustav Wieds Vej 10, DK-8000 Aarhus C, Denmark1.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Zachar
authors.affiliation: George H. Whipple Laboratory for Cancer Research, Departments of Pathology, Urology and Biochemistry, University of Rochester, Box 626, Rochester, NY 14642, USA2.
authors.forename: Chawnshang
authors.initials: C
authors.lastname: Chang
authors.affiliation: Department of Virus and Cancer, Danish Cancer Society, Gustav Wieds Vej 10, DK-8000 Aarhus C, Denmark1.
authors.forename: Peter
authors.initials: P
authors.lastname: Ebbesen
mesh_terms: D001483:Base Sequence; D001667:Binding, Competitive; D015153:Blotting, Western; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D015967:Gene Expression Regulation, Viral; D016356:Gene Products, tax / Q000235:genetics / Q000378:metabolism*; D015368:Human T-lymphotropic virus 1 / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D011401:Promoter Regions, Genetic / Q000235:genetics*; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D020218:Response Elements / Q000235:genetics; D018808:Transcription Factor AP-1 / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; D016356:Gene Products, tax; C539821:NR4A1 protein, human; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D018808:Transcription Factor AP-1; D014157:Transcription Factors