2010-12-292024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/681188摘要：當EB病毒在引發溶裂循環時，會表現Rta與Zta這兩個極早期蛋白質，活化與溶裂期進展相關基因的轉錄活性。目前我們發現Rta會藉由MCAF1與Sp1, Zta, AP-1及ATF2等蛋白質結合進而活化轉錄，因此MCAF1對EB病毒溶裂循環的活化扮演重要的角色。另外，MCAF1也會藉由MBD1結合在含有甲基化CpG的DNA上，與異染色質的結構形成相關，進而抑制轉錄。目前本人的研究證實Zta與Rta及MCAF1共同結合在EB病毒溶裂期基因的啟動子上的Zta結合序列（ZREs），引發溶裂期基因的協同活化。Rta也會藉由MCAF1與ATF2結合，促進會受到ATF2調控的基因進行轉錄。另外，Rta也會和diffused early antigen (EA-D) 及ssDNA-binding protein 這兩個EB病毒溶裂複製期重要的蛋白質結合，此現象顯示Rta在病毒溶裂期DNA複製的過程中扮演重要的角色。基於這些初步結果，本研究將證實 (a) Zta, MCAF1, 及Rta如何和其它轉錄因子結合在Zta結合序列上，進而協同地活化轉錄；(b) Rta如何與病毒複製起始複合體結合在溶裂複製起始點(oriLyt)上，進而引發溶裂複製；最後是(c) Zta, MCAF1,及Rta的結合如何影響EB病毒溶裂期啟動子的甲基化。本研究將對EB病毒溶裂期的活化機轉提供更深入的瞭解。<br> Abstract: The Epstein-Barr virus (EBV) encodes two transcription factors, Rta and Zta, during the immediate-early stage of the lytic cycle to activate the transcription of the genes required for viral lytic development. Meanwhile, Rta interacts with many transcription factors, including Sp1, Zta, AP-1, and ATF2, through the interaction with MCAF1 to enhance transcription. Therefore, MCAF1 is essential to the activation of the EBV lytic cycle. Additionally, MCAF1 interacts with MBD1 on methylated CpG to maintain the heterochromatin structure of the chromosome to repress transcription. My current investigation found that Zta and Rta interact through MCAF1 and form a complex on Zta-response elements in EBV lytic promoters to activate the transcription of EBV lytic genes synergistically. Rta also interacts with ATF2 through MCAF1 to enhance the transcription that is activated by ATF2. Furthermore, Rta interacts with diffused early antigen (EA-D) and colocalizes with EA-D and ssDNA-binding protein in the nucleus, two proteins that are critically involved in EBV lytic DNA replication. The interaction and colocalization suggest that Rta is critically involved in EBV lytic DNA replication. Based on these findings, the proposed study will investigate (a) how Zta, Rta, and MCAF1 recruit transcription factors to the Zta-response element (ZRE) to activate transcription synergistically; (b) how Rta recruits the components of the replication initiation complex to the lytic origin of replication (oriLyt) to initiate viral lytic DNA replication; and finally (c) how the interaction among Zta, MCAF1 and Rta affects the methylation of EBV lytic promoters. Results of this study provide further insight into the activation of the EBV lytic cycle.