Role of PML nuclear body proteins for establishment of EBV latent infection

描述(申请人提供)：爱泼斯坦-巴尔病毒(EBV)是最有效的转化病毒之一，它在几种人类癌症中发现，包括艾滋病患者的B细胞淋巴瘤，这些人的免疫功能受到艾滋病毒的抑制。我们实验室的长期目标是了解EBV潜伏蛋白如何介导B细胞转化。特别感兴趣的是EBNA2和EBNA-LP转录因子。EBNA2部分通过模拟细胞Notch信号通路来诱导病毒和细胞基因的表达。EBNA-LP是eBNA2的共激活因子，但其与eBNA2共激活的机制(S)仍不清楚。我们实验室最近的观察表明，EBNA-LP与早幼粒细胞核体(PML NB)蛋白Sp100相互作用并取代PML NBS，提示Sp100是介导EBNA-LP共激活功能的重要细胞辅助因子。此外，我们还证明了EBNA2氨基酸残基1-58包含一个寡聚化结构域，能够作为EBNA2转录激活功能的显性负抑制因子。为了进一步阐明Sp100如何介导EBNA-LP共激活功能，并测试是否可以利用EBNA2寡聚结构域来抑制EBV驱动的B细胞永生化，我们开展了以下目标：1)确定EBNA-LP如何介导Sp100从PML NBS移位，以及Sp100是否是EBNA2共激活所必需的；2)确定Sp100促进EBNA-LP共激活功能的机制；以及3)确定主要的阴性形式的EBNA2是否可以抑制EBV诱导的B淋巴细胞永生化。疱疹病毒修饰和/或调节PML和PML相关的NB蛋白。然而，目前尚不清楚PML NBS是一组蛋白质的集合，这些蛋白质介导了疱疹病毒进化来对抗的抗病毒细胞防御机制，或者病毒是否利用PML-NBS中的因子来帮助促进病毒基因表达和/或复制。我们对EBNA-LP和Sp100之间独特相互作用的研究将有助于对疱疹病毒和PML NBS之间的关系产生新的见解。EBNA2和/或EBNA-LP抑制剂的设计是一个潜在的实际应用，这将源于我们的研究。

DESCRIPTION (provided by applicant): Epstein-Barr virus (EBV) is one of the most potent transforming viruses and it is found in several human cancers, including B cell lymphomas in patients with AIDS who are immunosuppressed by HIV. The long- term goal of our laboratory is to understand how EBV latent proteins mediate B cell transformation. Of particular interest are the EBNA2 and EBNA-LP transcription factors. EBNA2 functions in part through mimicry of cellular Notch signaling pathways to induce expression of viral and cellular genes. EBNA-LP is a coactivator of EBNA2, but the mechanism(s) by which it coactivates EBNA2 remains elusive. Recent observations from our laboratory indicate that EBNA-LP interacts with and displaces the promyelocytic nuclear body (PML NB) protein Sp100 from PML NBs, suggesting that Sp100 is an important cellular cofactor that mediates EBNA-LP coactivation function. In addition, we have demonstrated that EBNA2 amino acid residues 1-58 comprise an oligomerization domain that is able to act as a dominant negative inhibitor of EBNA2 transcriptional activation function. To further clarify how Sp100 mediates EBNA-LP coactivation function and to test whether the EBNA2 oligomerization domain can be harnessed to inhibit EBV-driven B cell immortalization, we have developed the following aims: 1) To determine how EBNA-LP mediates Sp100 displacement from PML NBs and if Sp100 is essential for EBNA2 coactivation, 2) To determine the mechanism by which Sp100 contributes to EBNA-LP coactivation function, and 3) To determine whether dominant negative forms of EBNA2 can inhibit EBV-induced B lymphocyte immortalization. Herpesviruses modify and/or modulate PML and PML-associated NB proteins. However, it remains unclear whether PML NBs are a collection of proteins that mediate an antiviral cellular defense mechanism that herpesviruses have evolved to counteract or if viruses co-opt factors in PML-NBs to their advantage to help facilitate virus gene expression and/or replication. Our investigations into the unique interaction between EBNA-LP and Sp100 will help to yield new insights into the relationship of herpesviruses and PML NBs. Design of EBNA2 and/or EBNA-LP inhibitors is a potential practical application that will be derived from our studies.