title: A role for the nucleosome assembly proteins TAF-Iβ and NAP1 in the activation of BZLF1 expression and Epstein-Barr virus reactivation.
abstract: The reactivation of Epstein-Barr virus (EBV) from latent to lytic infection begins with the expression of the viral BZLF1 gene, leading to a subsequent cascade of viral gene expression and amplification of the EBV genome. Using RNA interference, we show that nucleosome assembly proteins NAP1 and TAF-I positively contribute to EBV reactivation in epithelial cells through the induction of BZLF1 expression. In addition, overexpression of NAP1 or the β isoform of TAF-I (TAF-Iβ) in AGS cells latently infected with EBV was sufficient to induce BZLF1 expression. Chromatin immunoprecipitation experiments performed in AGS-EBV cells showed that TAF-I associated with the BZLF1 promoter upon lytic induction and affected local histone modifications by increasing H3K4 dimethylation and H4K8 acetylation. MLL1, the host protein known to dimethylate H3K4, was found to associate with the BZLF1 promoter upon lytic induction in a TAF-I-dependent manner, and MLL1 depletion decreased BZLF1 expression, confirming its contribution to lytic reactivation. The results indicate that TAF-Iβ promotes BZLF1 expression and subsequent lytic infection by affecting chromatin at the BZLF1 promoter.
authors.affiliation: Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Sheila
authors.initials: S
authors.lastname: Mansouri
authors.forename: Shan
authors.initials: S
authors.lastname: Wang
authors.forename: Lori
authors.initials: L
authors.lastname: Frappier
mesh_terms: D000107:Acetylation; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins; D015967:Gene Expression Regulation, Viral; D004854:Herpesvirus 4, Human / Q000235:genetics* / Q000502:physiology; D056488:Histone Chaperones / Q000378:metabolism*; D011495:Histone-Lysine N-Methyltransferase; D006657:Histones / Q000378:metabolism; D006801:Humans; D008745:Methylation; D051788:Myeloid-Lymphoid Leukemia Protein / Q000378:metabolism; D009707:Nucleosomes / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011506:Proteins / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation; D014775:Virus Activation; D012359:tRNA Methyltransferases
chemical_list: C063676:BZLF1 protein, Herpesvirus 4, Human; D004268:DNA-Binding Proteins; D056488:Histone Chaperones; D006657:Histones; C497422:KMT2A protein, human; D009707:Nucleosomes; D011506:Proteins; C513473:SET protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D051788:Myeloid-Lymphoid Leukemia Protein; C498548:TRMO protein, human; D012359:tRNA Methyltransferases; D011495:Histone-Lysine N-Methyltransferase