Functions of EBNA1 in replication & partitioning of EBV

描述（由申请人提供）：eb病毒（EBV）是一种引起传染性单核细胞增多症的人类疱疹病毒。前瞻性流行病学研究表明EBV与至少两种恶性肿瘤——地方性伯基特淋巴瘤和鼻咽癌有因果关系。EBV的基因组在所有这些疾病中都是潜伏的，并且作为每个细胞周期复制一次的核片段维持，并在有丝分裂时有效分裂。了解EBV在每个细胞周期复制一次并分裂的机制将最终产生针对所有由潜伏性EBV感染引起的疾病的治疗方法。这些研究的长期目标是了解一般的病毒发作，但特定的EBV基因组如何维持在具有引起人类疾病能力的功能状态。EBV基因组维持和分配所需的唯一病毒蛋白是Epstein-Barr核抗原1 (EBNA1)，它通过其羧基末端dna结合域结合称为oriP的病毒顺式元件。OriP包含EBNA1的两组结合位点——DS和FR，前者是作为复制起点的区域，后者是当EBNA1与之结合时作为片段维持和分割元素的区域。我们最近发现EBNA1的氨基末端结构域有两个区域是AT-hook，与细胞蛋白（如原型AT-hook蛋白HMGA1a）的AT-hook相对应。为了证实这一观察结果，我们已经证明我们可以用HMGA1a的at钩在功能上取代EBNA1的n端。在这个建议中，我们建议在三个方面扩展我们的研究：

DESCRIPTION (provided by applicant): Epstein-Barr virus (EBV) is a human herpesvirus that causes infectious mononucleosis. Prospective epidemiologic studies indicate that EBV is causally associated with at least two malignancies - endemic Burkitt's lymphoma, and nasopharyngeal carcinoma. EBV's genome is latent in all these diseases, and is maintained as a nuclear episome that replicates once per cell cycle, and is efficiently partitioned at mitosis. Understanding the mechanism by which EBV episomes are replicated once per cell-cycle and partitioned will ultimately yield therapies against all diseases caused by a latent EBV infection. The long-range goal of these studies is to understand how viral episomes in general, but EBV genomes in specific, are maintained in a functional state with the capacity to cause human disease. The only viral protein that is required for EBV genome maintenance and partitioning is the Epstein-Barr nuclear antigen 1 (EBNA1), which binds a viral cis-element termed oriP through its carboxy-terminal DNA-binding domain. OriP contains two sets of binding sites for EBNA1 - DS, a region that serves as an origin of replication, and FR, a region that serves as an episome maintenance and partitioning element when EBNA1 is bound to it. We have recently discovered that the amino-terminal domain of EBNA1 has two regions within it that are AT-hooks, corresponding to the AT-hooks of cellular proteins such as the prototypic AT-hook protein HMGA1a. Confirming this observation, we have demonstrated that we can functionally replace the N-terminus of EBNA1 with the AT-hooks of HMGA1a. In this proposal we propose to extend our studies in three areas: 1. To characterize the roles of the AT-hook regions of EBNA1 in chromosome tethering and episome maintenance. 2. To utilize a novel replicon and fusion protein to understand the function of EBNA1 in replication. 3. To use viral genetics to determine the functions of EBNA1 in the immortalization of naive B-cells by EBV