The Epstein-Barr virus promoter initiating B-cell transformation is activated by RFX proteins and the B-cell-specific activator protein BSAP/Pax5.
Epstein-Barr virus (EBV)-induced B-cell growth transformation, a central feature of the virus' strategy for colonizing the human B-cell system, requires full virus latent gene expression and is initiated by transcription from the viral promoter Wp. Interestingly, when EBV accesses other cell types, this growth-transforming program is not activated. The present work focuses on a region of Wp which in reporter assays confers B-cell-specific activity. Bandshift studies indicate that this region contains three factor binding sites, termed sites B, C, and D, in addition to a previously characterized CREB site. Here we show that site C binds members of the ubiquitously expressed RFX family of proteins, notably RFX1, RFX3, and the associated factor MIBP1, whereas sites B and D both bind the B-cell-specific activator protein BSAP/Pax5. In reporter assays with mutant Wp constructs, the loss of factor binding to any one of these sites severely impaired promoter activity in B cells, while the wild-type promoter could be activated in non-B cells by ectopic BSAP expression. We suggest that Wp regulation by BSAP helps to ensure the B-cell specificity of EBV's growth-transforming function.
Tierney
R
R
CRC Institute for Cancer Studies, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
Kirby
H
H
Nagra
J
J
Rickinson
A
A
Bell
A
A
D001402:B-Lymphocytes / Q000821:virology*; D001483:Base Sequence; D002460:Cell Line; D002461:Cell Line, Transformed; D002472:Cell Transformation, Viral; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015967:Gene Expression Regulation, Viral; D017930:Genes, Reporter; D004854:Herpesvirus 4, Human / Q000235:genetics* / Q000502:physiology; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism*; D051757:PAX5 Transcription Factor; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics*; D000071701:Regulatory Factor X Transcription Factors; D000071716:Regulatory Factor X1; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection
D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D051757:PAX5 Transcription Factor; C497281:PAX5 protein, human; C000605537:RFX1 protein, human; C000605540:RFX3 protein, human; D000071701:Regulatory Factor X Transcription Factors; D000071716:Regulatory Factor X1; D014157:Transcription Factors