title: The transcription elongation factor ELL2 is specifically upregulated in HTLV-1-infected T-cells and is dependent on the viral oncoprotein Tax.
abstract: The oncoprotein Tax of human T-cell leukemia virus type 1 (HTLV-1) is a potent transactivator of viral and cellular transcription. Here, we identified ELL2 as the sole transcription elongation factor to be specifically upregulated in HTLV-1-/Tax-transformed T-cells. Tax contributes to regulation of ELL2, since transient transfection of Tax increases ELL2 mRNA, Tax transactivates the ELL2 promoter, and repression of Tax results in decrease of ELL2 in transformed T-lymphocytes. However, we also measured upregulation of ELL2 in HTLV-1-transformed cells exhibiting undetectable amounts of Tax, suggesting that ELL2 can still be maintained independent of continuous Tax expression. We further show that Tax and ELL2 synergistically activate the HTLV-1 promoter, indicating that ELL2 cooperates with Tax in viral transactivation. This is supported by our findings that Tax and ELL2 accumulate in nuclear fractions and that they co-precipitate upon co-expression in transiently-transfected cells. Thus, upregulation of ELL2 could contribute to HTLV-1 gene regulation.
authors: Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany. Electronic address: melanie.mann@viro.med.uni-erlangen.de.
authors: Melanie C
authors: MC
authors: Mann
authors: Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany. Electronic address: sarah.strobel@viro.med.uni-erlangen.de.
authors: Sarah
authors: S
authors: Strobel
authors: Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany. Electronic address: bernhard.fleckenstein@viro.med.uni-erlangen.de.
authors: Bernhard
authors: B
authors: Fleckenstein
authors: Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany. Electronic address: andrea.kress@viro.med.uni-erlangen.de.
authors: Andrea K
authors: AK
authors: Kress
mesh_terms: D015967:Gene Expression Regulation, Viral; D016356:Gene Products, tax / Q000235:genetics / Q000378:metabolism*; D015490:HTLV-I Infections / Q000235:genetics* / Q000378:metabolism / Q000821:virology; D015368:Human T-lymphotropic virus 1 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D011401:Promoter Regions, Genetic; D013601:T-Lymphocytes / Q000378:metabolism / Q000821:virology*; D015533:Transcriptional Activation; D035602:Transcriptional Elongation Factors / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation
chemical_list: C447613:ELL2 protein, human; D016356:Gene Products, tax; D035602:Transcriptional Elongation Factors; C514970:tax protein, Human T-lymphotrophic virus 1
keywords: ELL2; HTLV-1; Human T-cell leukemia virus type 1; Tax; Transcription elongation factor