Translational Regulation of EBV BGLF4 Protein Kinase

• Main Authors: kun-Liang Chen, 陳坤良
• Other Authors: 陳美如
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/36907318528850026123

碩士 === 國立臺灣大學 === 微生物學研究所 === 94 === Epstein-Barr virus (EBV) BGLF4 encodes the serine/threonine protein kinase which can phosphorylate several viral substrates including BMRF1, Zta, EBNA-LP and cellular translation factor EF-1d. BGLF4 was detected in viral DNA replication compartment and mature virion, suggesting it may play roles in regulating virus DNA replication and encapsidation or egress process. In our previous study, two transcription start sites at -255 and -201 upstream of translation initiation site were identified in 5’-RACE analysis. In this study, we used another primer sets to further identify another transcription start sites of BGLF4 at -472 nt, which is 25 nt downstream of a putative TATA box. To examine whether the long 5’ untranslated region (UTR) of BGLF4 might function as the internal ribosome entry site (IRES), dual luciferase reporter assay was performed with DNA or RNA transfection to demonstrate the translation enhancement effect of BGLF4 5’-UTR. We further demonstrated the BGLF4 IRES activity was enhanced under tunicamycin treatment which would induce the ER stress. Additionally, induction of ER stress was observed upon EBV reactivation in anti-IgG induced EBV positive Akata cells as revealed by the detection of the spliced form of XBP-1. Simultaneously, BGLF4 IRES activity was enhanced upon EBV reaction induced by Rta in EBV-positive NA cells. Data here thus suggest the 5’-UTR of BGLF4 may ensure BGLF4 expression while the cap-dependent translation machinery is blocked in lytic virus replicating cells.