Role of Epstein-Barr Virus in Burkitt Lymphoma

描述(由申请人提供)：这项资助工作的长期目标是确定爱泼斯坦-巴尔病毒(EBV)在Burkitt淋巴瘤(BL)中的作用。Burkitt淋巴瘤是一种B细胞肿瘤，发生在不同的地理区域，也与艾滋病毒感染和艾滋病造成的免疫抑制有关。这项拨款的基本假设是，尽管已知的病毒转化基因在肿瘤细胞中缺乏表达，但EBV对白血病有直接贡献。这得到了以下观察的支持：BL细胞系Akata的致瘤潜力依赖于EBV感染和至少两种病毒基因产物，EBV小RNA EBER-1和EBER-2。然而，EBER RNA对肿瘤潜能的贡献相对于EBV感染的整体贡献是部分的，这表明在BL细胞感染过程中表达的额外病毒基因是重要的。这项拟议工作的近期目标是确定EBER RNAs和其他EBV基因产物对BL细胞的致瘤潜力和淋巴肿瘤本身的机制贡献。提出了三个具体目标。在目标1下，我们将确定EBER RNAs的细胞靶标，并定义它们被调控的机制。我们将讨论EBER功能的两个潜在机制，这两个机制是由先前的实验观察提出的。第一种是EBER RNAs通过与细胞基因RNAs的直接相互作用，在转录后基因沉默中发挥作用。第二，基于EBERs与细胞翻译机制组件的已知相互作用，EBERs调控特定细胞mRNAs的翻译。在目标2下，我们将确定EBV BamHI向右转录本(BART)编码的蛋白质对BL细胞致瘤潜力的贡献，特别是这些蛋白质中是否有任何蛋白质与EBV增强BL细胞的存活有关，这归因于病毒在生长限制条件下强制下调c-myc原癌蛋白。在目标3中，我们将使用Emu-myc转基因小鼠BL的小鼠模型来评估在BL细胞系中表达的EBV基因对实际淋巴癌发生的重要性，在该模型中，c-myc原癌基因的表达与在BL中一样，结构性地在B淋巴细胞中过表达。具体地说，我们将在这些小鼠的B细胞中表达EBV基因，以确定这是否加速了c-Myc诱导的淋巴瘤的发生，如果是，我们将确定这种导致淋巴瘤的遗传和生化基础。

DESCRIPTION (provided by applicant): The long-term objective of the work supported by this grant is to define the role of Epstein-Barr virus (EBV) in Burkitt lymphoma (BL), a B-cell tumor that occurs in geographically distinct regions, and which is also associated with immunosuppression as a consequence of HIV infection and AIDS. The underlying hypothesis of this grant is that EBV contributes directly to BL, despite lack of expression of the known viral transforming genes within the tumor cells. This is supported by the observation that the tumorigenic potential of the BL cell line Akata is dependent on EBV infection and at least two viral gene products the EBV small RNAs EBER-1 and EBER-2. The contribution of the EBER RNAs to tumorigenic potential, however, is partial relative to that conferred by EBV infection as a whole, indicating that additional viral genes expressed during infection of BL cells are important. The immediate goals of the proposed work are to define the mechanistic contributions of the EBER RNAs and other EBV gene products to the tumorigenic potential of BL cells and to lymphomagenesis itself. Three specific aims are proposed. Under Aim 1, we will identify the cellular targets of the EBER RNAs and define the mechanisms through which they are regulated. We will address two potential mechanisms of EBER function that are suggested by previous experimental observations. The first is that the EBER RNAs function in posttranscriptional gene silencing through direct RNA:RNA interactions with cellular gene RNAs. The second, based on known interactions of the EBERs with components of the cellular translational machinery, is that the EBERs regulate translation of specific cellular mRNAs. Under Aim 2, we will define the contributions of proteins encoded by the EBV BamHI rightward transcripts (BARTs) to BL-cell tumorigenic potential, and in particular whether any of these proteins are responsible for the enhanced survival conferred upon BL cells by EBV that is attributed to viral-enforced down-regulation of the c-MYC proto-oncoprotein under growth-limiting conditions. Under Aim 3, we will assess the importance of EBV genes expressed in BL cell lines to actual lymphomagenesis using the murine model of BL, the Emu-myc transgenic mouse, in which expression of the c-myc proto-oncogene, as in BL, is constitutively overexpressed in B lymphocytes. Specifically, we will express the EBV genes within the B cells of these mice to determine whether this accelerates c-Myc-induced lymphomagenesis, and if so, we will identify the genetic and biochemical basis for this contribution to lymphoma.