Function of the Epstein-Barr Virus EBNA-A3 Protein

描述（由申请人提供）：拟议研究的长期目标是确定潜伏性eb病毒（EBV）核蛋白EBNA-3A对eb病毒诱导的B淋巴细胞增殖的重要贡献。EBV诱导原发B淋巴细胞增殖的能力被认为是建立长期潜伏期的核心，从而导致EBV相关恶性肿瘤的发展，通常发生在原发感染数年后。尽管HAART已经出现，EBV相关的恶性肿瘤仍在hiv感染患者中发生，因此EBV建立潜伏期的机制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点是Jkappa， EBNA-3A通过Jkappa抑制转录。我们的初步研究以及其他实验室的数据有力地支持了我们的假设，即EBNA-3A也具有与jkappa无关的功能。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及其下游作用的了解仍存在重大空白。为了阐明EBNA-3A在ebv介导的增殖中的作用，我们提出了三个综合目标来解决这些知识上的空白。通过转录谱分析，我们已经确定了EBNA-3A调控的细胞基因，这些基因可能与ebv诱导的增殖具有生物学相关性。在Aim 1下，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Aim 2中，我们将通过纯化含有EBNA-3A的蛋白复合物，鉴定EBNA-3A在ebv转化的B淋巴细胞中介导其作用的蛋白。EBNA-3蛋白在伯基特淋巴瘤的一个亚群中表达的发现构成了Aim 3的基础，在Aim 3中，我们将确定EBNA-3A是否在异种移植模型中增加了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。这三个目标得到shiv a . Prasad博士的支持。

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.