title: Epigenetic histone modification of Epstein-Barr virus BZLF1 promoter during latency and reactivation in Raji cells.
abstract: The Epstein-Barr virus (EBV) predominantly establishes latent infection in B cells, and the reactivation of the virus from latency is dependent on the expression of the viral BZLF1 protein. The BZLF1 promoter (Zp) normally exhibits only low basal activity but is activated in response to chemical or biological inducers, such as 12-O-tetradecanoylphorbol-13-acetate (TPA), calcium ionophores, or histone deacetylase (HDAC) inhibitors. In some cell lines latently infected with EBV, an HDAC inhibitor alone can induce BZLF1 transcription, while the treatment does not enhance expression in other cell lines, such as B95-8 or Raji cells, suggesting unknown suppressive mechanisms besides histone deacetylation in those cells. Here, we found the epigenetic modification of the BZLF1 promoter in latent Raji cells by histone H3 lysine 27 trimethylation (H3K27me3), H3K9me2/me3, and H4K20me3. Levels of active markers such as histone acetylation and H3K4me3 were low in latent cells but increased upon reactivation. Treatment with 3-deazaneplanocin A (DZNep), an inhibitor of H3K27me3 and H4K20me3, significantly enhanced the BZLF1 transcription in Raji cells when in combination with an HDAC inhibitor, trichostatin A (TSA). The knockdown of Ezh2 or Suv420h1, histone methyltransferases for H3K27me3 or H4K20me3, respectively, further proved the suppression of Zp by the methylations. Taken together, the results indicate that H3K27 methylation and H4K20 methylation are involved, at least partly, in the maintenance of latency, and histone acetylation and H3K4 methylation correlate with the reactivation of the virus in Raji cells.
authors.affiliation: Division of Virology, Aichi Cancer Center Research Institute, Kanokoden, Chikusa-ku, Nagoya, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Murata
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Kondo
authors.forename: Atsuko
authors.initials: A
authors.lastname: Sugimoto
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kawashima
authors.forename: Shinichi
authors.initials: S
authors.lastname: Saito
authors.forename: Hiroki
authors.initials: H
authors.lastname: Isomura
authors.forename: Teru
authors.initials: T
authors.lastname: Kanda
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Tsurumi
mesh_terms: D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D002460:Cell Line; D015254:DNA Modification Methylases / Q000037:antagonists & inhibitors; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D000077209:Decitabine; D000071221:Enhancer of Zeste Homolog 2 Protein; D044127:Epigenesis, Genetic; D015967:Gene Expression Regulation, Viral / Q000187:drug effects; D020868:Gene Silencing; D004854:Herpesvirus 4, Human / Q000235:genetics*; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics; D006657:Histones / Q000378:metabolism*; D006801:Humans; D063151:Polycomb Repressive Complex 2; D011401:Promoter Regions, Genetic / Q000187:drug effects; D015534:Trans-Activators / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D017735:Virus Latency / Q000235:genetics*
chemical_list: C063676:BZLF1 protein, Herpesvirus 4, Human; D004268:DNA-Binding Proteins; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D015534:Trans-Activators; D014157:Transcription Factors; D000077209:Decitabine; D015254:DNA Modification Methylases; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D011495:Histone-Lysine N-Methyltransferase; D063151:Polycomb Repressive Complex 2; D001374:Azacitidine