title: TORC1 and TORC2 coactivators are required for tax activation of the human T-cell leukemia virus type 1 long terminal repeats.
abstract: Human T-cell leukemia virus type 1 (HTLV-1) Tax protein activates viral transcription from the long terminal repeats (LTR). Mechanisms through which Tax activates LTR have been established, but coactivators of this process remain to be identified and characterized. Here we show that all three members of the TORC family of transcriptional regulators are coactivators of Tax for LTR-driven expression. TORC coactivation requires CREB, but not ATF4 or other bZIP factors. Tax physically interacts with TORC1, TORC2, and TORC3 (TORC1/2/3), and the depletion of TORC1/2/3 inhibited Tax activity. TORC coactivation can be further enhanced by transcriptional coactivator p300. In addition, coactivators in the p300 family are required for full activity of Tax independently of TORC1/2/3. Thus, both TORC and p300 families of coactivators are essential for optimal activation of HTLV-1 transcription by Tax.
authors.affiliation: Department of Biochemistry, The University of Hong Kong, 3/F Laboratory Block, Faculty of Medicine Building, 21 Sassoon Road, Pokfulam, Hong Kong.
authors.forename: Yeung-Tung
authors.initials: YT
authors.lastname: Siu
authors.forename: King-Tung
authors.initials: KT
authors.lastname: Chin
authors.forename: Kam-Leung
authors.initials: KL
authors.lastname: Siu
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Yee Wai Choy
authors.forename: Kuan-Teh
authors.initials: KT
authors.lastname: Jeang
authors.forename: Dong-Yan
authors.initials: DY
authors.lastname: Jin
mesh_terms: D051701:Activating Transcription Factor 4 / Q000235:genetics / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism; D015967:Gene Expression Regulation, Viral / Q000502:physiology; D016356:Gene Products, tax / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D015368:Human T-lymphotropic virus 1 / Q000502:physiology*; D006801:Humans; D010750:Phosphoproteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D020079:Terminal Repeat Sequences / Q000502:physiology*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology; D014775:Virus Activation / Q000502:physiology*; D050880:p300-CBP Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C497109:ATF4 protein, human; C115163:CREB1 protein, human; C500984:CRTC1 protein, human; C493245:CRTC2 protein, human; C495791:CRTC3 protein, human; D017362:Cyclic AMP Response Element-Binding Protein; D016356:Gene Products, tax; D010750:Phosphoproteins; D015534:Trans-Activators; D014157:Transcription Factors; D051701:Activating Transcription Factor 4; D050880:p300-CBP Transcription Factors