EB病毒轉活化子Rta與細胞因子nuclear cap binding protein 1 (NCBP1)之結合促進EB病毒特早期基因BZLF1成熟mRNA表現

Abstract

EB病毒的特早期基因BRLF1所表現出的轉活化子，Rta，可調控病毒由潛伏期進入溶裂期。先前Yeast two hybrid研究結果顯示，Rta與NCBP1蛋白質有交互作用。本實驗以GST沉澱法、雙向免疫沉澱法及免疫螢光染色實驗分別證實兩者之交互作用及其於細胞中位置之相關性，並以不同的NCBP1刪減片段蛋白質與GST融合的Rta蛋白質進行GST沉澱法，發現NCBP1蛋白質藉由其胺基端及羧基端與Rta蛋白質之胺基端320個胺基酸形成構形上之交互作用。進一步實驗發現NCBP1蛋白質會加強由TPA及sodium butyrate所誘發EB病毒溶裂期之進行，然而，Rta蛋白質之大量表現及溶裂期之進行並不改變細胞中NCBP1蛋白質的表現量，因此推論，或許NCBP1蛋白質之生理功能在EB病毒溶裂期進行中扮演著重要的角色。最後，觀察到NCBP1蛋白質會加強由Rta所誘發成熟的Zta mRNA表現量。

Abstract Transactivator R, Rta, encoded by an EBV immediate-early gene, BRLF1, mediates the switch from latency into the lytic cycle. A yeast two hybrid study finds that Rta interacts with NCBP1 protein. In this study, GST pull-down assay, co-immunoprecipitation assay and immunofluorescent staining were performed to investigate the interaction between Rta and NCBP1 and their relative localization in cells. By using different NCBP1 deletion mutant proteins, we demonstrated that amino- and carboxyl- terminus of NCBP1 protein interacts with the amino-terminal 320 region of Rta. Additionally, NCBP1 enhances the EBV lytic gene expression which is induced by TPA and sodium butyrate. Yet, the endogenous NCBP1 protein expression remains unchanged after lytic induction. As a result, we propose that NCBP1 protein plays an important role in promoting the EBV lytic cycle progression. Finally, expression of mature Zta mRNA induced by Rta was increased under the influence of NCBP1 protein.