Transcriptional activation of immediate-early gene ETR101 by human T-cell leukaemia virus type I Tax

• Published in: Journal of general virology 2003-12, Vol.84 (12), p.3203-3214
• Main Authors: Chen, Li, Ma, Shiliang, Li, Bo, Fink, Trine, Zachar, Vladimir, Takahashi, Mark, Cuttichia, Jamie, Tsui, Lap-Chee, Ebbesen, Peter, Liu, Xiangdong
• Format: Article
• Language: English
• Subjects: Animals; Base Sequence; Cell Line, Tumor; Cyclic AMP Response Element-Binding Protein - physiology; Endopeptidases; ETR101 gene; Gene Expression Regulation; Gene Products, tax - genetics; Gene Products, tax - metabolism; Gene Products, tax - physiology; Genes, Immediate-Early; Human T-lymphotropic virus 1; Human T-lymphotropic virus 1 - genetics; Human T-lymphotropic virus 1 - physiology; Humans; Molecular Sequence Data; Mutagenesis, Site-Directed; Oncogene Proteins; Oncogene Proteins, Fusion - genetics; Promoter Regions, Genetic; Proto-Oncogene Proteins; Sequence Alignment; Transcriptional Activation; Ubiquitin Thiolesterase
• ISSN: 0022-1317; 1465-2099
• DOI: 10.1099/vir.0.19283-0

1 Laboratory for Stem Cell Research, Aalborg University, Gustav Wieds Vej 10, DK-8000 Aarhus C, Denmark 2 Department of Virus and Cancer, Danish Cancer Society, Gustav Wieds Vej 10, DK-8000 Aarhus C, Denmark 3 Ontario Cancer Institute, Toronto, Ontario, Canada M5G 1Z8 4 Program of Genetics and Genomic Biology, Center for Applied Genomics, Hospital for Sick Children Research Institute, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8 Correspondence Xiangdong Liu (at Hospital for Sick Children Research Institute) liu{at}genet.sickkids.on.ca Human T-cell leukaemia virus type I (HTLV-I) Tax regulates viral and cellular gene expression through interactions with multiple cellular transcription pathways. This study describes the finding of immediate–early gene ETR101 expression in HTLV-I-infected cells and its regulation by Tax. ETR101 was persistently expressed in HTLV-I-infected cells but not in HTLV-I uninfected cells. Expression of ETR101 was dependent upon Tax expression in the inducible Tax-expressing cell line JPX-9 and also in Jurkat cells transiently transfected with Tax-expressing vectors. Tax transactivated the ETR101 gene promoter in a transient transfection assay. A series of deletion and mutation analyses of the ETR101 gene promoter indicated that a 35 bp region immediately upstream of the TATA-box sequence, which contains a consensus cAMP response element (CRE) and a G+C-rich sequence, is the critical responsive element for Tax activation. Site-directed mutagenesis analysis of the 35 bp region suggested that both the consensus CRE motif and its upstream G+C-rich sequence were critical for Tax transactivation. Electrophoretic mobility shift analysis (EMSA) using the 35 bp sequence as probe showed the formation of a specific protein–DNA complex in HTLV-I-infected cell lines. EMSA with specific antibodies confirmed that the CREB transcription factor was responsible for formation of this specific protein–DNA complex. These results suggested that Tax directly transactivated ETR101 gene expression, mainly through a CRE sequence via the CREB transcription pathway.