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的EB病毒(EBV)核蛋白EBNA-3A对EBV诱导的B淋巴细胞增殖的重要贡献。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核心，从而导致EBV相关恶性肿瘤的发展，这些肿瘤通常发生在初次感染数年后。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它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来自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Jkappa独立功能。尽管EBNA-3A的Jkappa依赖和独立功能都可能在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影响的了解存在显著差距。为了阐明EBNA-3A促进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差距。利用转录图谱，我们已经确定了受EBNA-3A调控的细胞基因，这些基因可能与EBV诱导的增殖有关。在目标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。在目标2下，我们将通过纯化含有EBNA-3A的蛋白质复合体来鉴定EBNA-3A通过其在EBV转化的B淋巴细胞中介导其作用的蛋白质。EBNA-3蛋白在Burkitt淋巴瘤的一个子集中表达的发现构成了目标3的基础，在那里我们将确定EBNA-3A是否通过异种移植模型增加了BL细胞的致瘤性，以及它是否影响了BL小鼠模型的肿瘤发展。这三个目标得到了Shiv A.Prasad博士的支持。 移植免疫生物科科长 过敏、免疫学和移植学部 美国国家过敏症和传染病研究所 6610 Rockledge Dr.，Rm.3035 我们的初步研究将极大地扩展我们对EBNA-3A的生化功能的理解，以及介导其在EB病毒介导的B淋巴细胞永生化中的重要作用的下游效应器，从而促进这种致癌疱疹病毒的致病潜力。

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.