Function of the Epstein-Barr Virus EBNA-A3 Protein

描述（由申请方提供）：拟定研究的长期目标是确定潜伏性爱泼斯坦-巴尔病毒（EBV）核蛋白EBNA-3A对EBV诱导的B淋巴细胞增殖的重要作用。EBV诱导原代B淋巴细胞增殖的能力被认为是建立长期潜伏期的关键，并因此是通常在原发感染后数年发生的EBV相关恶性肿瘤的发展的关键。尽管HAART的出现，EBV相关的恶性肿瘤仍继续发生在HIV感染的患者中，因此EBV建立潜伏期的机制以及其在疾病发展中的作用值得进一步研究。EBNA-3A在EBV永生化细胞中的一个重要靶标是Jkappa，EBNA-3A通过Jkappa抑制转录。我们的初步研究，以及来自其他实验室的数据，强烈支持我们的假设，EBNA-3A也有Jkappa独立的功能。尽管EBNA-3A的Jkappa依赖性和非依赖性功能都可能在EBV诱导的细胞增殖中发挥重要作用，但我们对这些额外途径和下游效应的认识存在重大差距。为了阐明EBNA-3A有助于EBV介导的增殖的功能，我们提出了三个综合目标来解决我们知识中的这些空白。使用转录谱分析，我们已经确定了细胞基因的EBNA-3A，很可能是生物学相关的EBV诱导的增殖。根据目标1，我们将确定EBNA-3A调节这些基因的途径，并确定它们与EBV永生化B细胞持续增殖的生物学相关性。在目标2中，我们将通过纯化含有EBNA-3A的蛋白复合物来鉴定EBNA-3A介导其在EBV转化的B淋巴细胞中的作用的蛋白。EBNA-3蛋白在伯基特淋巴瘤亚群中表达的发现形成了目标3的基础，在目标3中，我们将使用异种移植模型确定EBNA-3A是否增加BL细胞的致瘤性，以及它是否影响BL小鼠模型中的肿瘤发展。这三个目标，支持由希夫A。Prasad博士 移植免疫生物学分支主任 过敏、免疫学和移植部 国家过敏和传染病研究所 6610岩礁博士，RM. 3035 Bethesda，MD 20892-6601我们的初步研究应该极大地扩展我们对EBNA-3A的生化功能以及介导其对EBV介导的B淋巴细胞永生化的重要贡献的下游效应物的理解，从而扩展我们对这种致癌疱疹病毒的致病潜力的理解。

DESCRIPTION (provided by applicant): The long term objective of the proposed research is to define the essential contribution of the latent Epstein- Barr virus (EBV) nuclear protein EBNA-3A to EBV-induced proliferation of B lymphocytes. EBV's ability to induce proliferation of primary B lymphocytes is believed to be central to the establishment of long term latency, and thus to the development of EBV-associated malignancies that typically occur years after primary infection. EBV-associated malignancies continue to occur in HIV-infected patients despite the advent of HAART, and thus the mechansims by which EBV establishes latency, as well as its role in development of disease, warrant futher investigation. An important target of EBNA-3A in EBV-immortalized cells is Jkappa, through which EBNA-3A represses transcription. Our preliminary studies, as well as data from other labs, strongly support our hypothesis that EBNA-3A also has Jkappa-independent functions. Although both Jkappa-dependent and -independent functions of EBNA-3A are likely to play significant roles in EBV-induced cellular proliferation, there are significant gaps in our knowledge regarding these additional pathways and the downstream effects. To elucidate the functions of EBNA-3A that contribute to EBV-mediated proliferation, we propose three integrated aims to address these gaps in our knowledge. Using transcriptional profiling, we have identified cellular genes regulated by EBNA-3A that are likely to be biologically relevant to EBV-induced proliferation. Under Aim 1, we will identify the pathways through which EBNA-3A regulates these genes, as well as determine their biological relevance to continued proliferation of EBV-immortalized B-cells. Under Aim 2, we will identify proteins through which EBNA-3A mediates its effects in EBV-transformed B lymphocytes by purification of EBNA-3A containing protein complexes. The finding that the EBNA-3 proteins are expressed in a subset of Burkitt lymphomas forms the basis for Aim 3, where we will determine whether EBNA-3A increases the tumorigenicity of BL cells using a xenograft model and whether it affects tumor development in a mouse model of BL. These three aims, supported byShiv A. Prasad, Ph.D. Chief, Transplantation Immunobiology Branch Division of Allergy, Immunology, and Transplantation National Institute of Allergy and Infectious Diseases - NIH 6610 Rockledge Dr., Rm. 3035 Bethesda, MD 20892-6601 our preliminary studies, should greatly extend our understanding of the biochemical functions of EBNA-3A, as well as the downstream effectors mediating its essential contribution to EBV-mediated immortalization of B lymphocytes, and thus the pathogenic potential of this oncogenic herpesvirus.