Role of the histone H3 lysine 9 methyltransferase Suv39 h1 in maintaining Epsteinn–Barr virus latency in B95–8 cells

Abstract

The ability of Epstein-Barr Virus (EBV) to establish latent infection is associated with infectious mononucleosis and a number of malignancies. In EBV, the product of the BZLF1 gene (ZEBRA) acts as a master regulator of the transition from latency to the lytic replication cycle in latently infected cells. EBV latency is primarily maintained by hypoacetylation of histone proteins in the BZLF1 promoter by histone deacetylases. Although histone methylation is involved in the organization of chromatin domains and has a central epigenetic role in gene expression, its role in maintaining EBV latency is not well understood. Here we present evidence that the histone H3 lysine 9 (H3K9) methyltransferase suppressor of variegation 3-9 homolog 1 (Suv39 h1) transcriptionally represses BZLF1 in B95-8 cells by promoting repressive trimethylation at H3K9 (H3K9me3). Suv39 h1 significantly inhibited basal expression and ZEBRA-induced BZLF1 gene expression in B95-8 B cells. However, mutant Suv39 h1 lacks the SET domain responsible for catalytic activity of histone methyl transferase and thus had no such effect. BZLF1 transcription was augmented when Suv39 h1 expression was knocked down by siRNA in B95-8 cells, but not in Akata or Raji cells. In addition, treatment with a specific Suv39 h1 inhibitor, chaetocin, significantly enhanced BZLF1 transcription. Furthermore, chromatin immunoprecipitation assays revealed the presence of Suv39 h1 and H3K9me3 on nucleosome histones near the BZLF1 promoter. Taken together, these results suggest that Suv39 h1-H3K9me3 epigenetic repression is involved in BZLF1 transcriptional silencing, providing a molecular basis for understanding the mechanism by which EBV latency is maintained.

Butyric Acid in Saliva of Chronic Periodontitis Patients Induces Transcription of the EBV Lytic Switch Activator BZLF1: A Pilot Study

“…Preparation of mRNA and real-time polymerase chain reaction (PCR). The experimental procedures for RNA purification and realtime PCR were performed as previously described (18,21). Briefly, Daudi cells were washed once with ice-cold phosphate-buffered saline (PBS) and homogenized using a QIAshredder (QIAGEN, Alameda, CA, USA), while total RNA was purified using a RNeasy Mini Kit (QIAGEN).…”

“…Luciferase assay was then performed using a Dual-Luciferase Reporter Assay System (Promega), according to the in vivo 34: 587-594 (2020) manufacturer's instructions. The experimental procedure for the luciferase assay has been previously reported (20,21). B95-8-221 Luc.…”

Epstein-Barr virus lytic reactivation regulation and its pathogenic role in carcinogenesis

“…Repressive histone modifications, such as H3K27me3, H3K9me2/me3, and H4K20me3 have been identified at Zp or Rp, and correlate with inactivation of both IE promoters, maintaining viral latency. Nevertheless, H3K4me3 allows the virus to express Zta 49-51 (Figure 2). …”

Effects of initial periodontal therapy on the prevalence of Epstein-Barr virus DNA and Porphyromonas gingivalis in Japanese chronic periodontitis patients

“…And the results of in-situ hybridization using serial section by EBV-encoded small RNA (EBRE) showed a large number of B cells in the same location were EBER-positive [18]. Latent EBV could be induced into the lytic replication cycle by treatment with several inducers, such as anti-immunoglobulin, butyric acid, calcium ionophore, phorbol 12-myristate 13-acetate and transforming growth factor-β [7,8,33]. The EBV BZLF1 gene product ZEBRA is a regulator of the transition from latent form to the lytic replication cycle.…”

“…Spread within families is thought to be a common route of EBV transmission by salivary contact. The virus infects first within oropharyngeal epithelium, and later primarily within B lymphocytes are invaded via CD21 receptors, where it establishes a lifelong latent infection [5][6][7][8][9]. EBV has been linked to the development of several malignant tumors, including Burkitt's lymphoma, Hodgkin's disease certain forms of T-cell lymphoma, lymphoproliferative disease in immunosuppressed individuals, nasopharyngeal carcinoma and a proportion of gastric cancers [10][11][12].…”