MOLECULAR MECHANISM OF CO-ACTIVATION ACTIVITIES OF EPSTEIN-BARR VIRUS NUCLEARPROTEIN EBNA-LP

eb病毒（EBV）感染可引起人原代B淋巴细胞生长转化。EBV核蛋白EBNA-2和EBNA-LP在转化过程中起关键作用。这些蛋白在EBV感染的早期同时表达。EBNA-2是一种上调病毒和细胞启动子转录活性的反激活子。EBNA-LP作为辅助因子刺激EBNA-2介导的交易激活（Harada & Kieff， J.Virol）。, 1997)。为了探讨EBNA-2和ena - lp共同调控的转录激活机制，我们研究了EBNA-2和ena - lp之间的直接和间接相互作用，以及ena - lp与细胞蛋白的关联。(1)从旗子- lp稳定表达的B淋巴母细胞中，用标记的EBNA-LP免疫沉淀蛋白，通过测序鉴定出EBNA-LP相关蛋白。证实了EBNA-LP与Hsp70（72/73）的关联，并鉴定了DNA-PK催化亚基HA95、Hsp27、脯氨酰4-羟化酶α-1亚基α-tublin、β-tublin的序列(J.Virol；, 2001 b)。(2) EBNA-2至少有两个结构域，分别是氨基酸1 ~ 60和96 ~ 210，它们独立介导同型关联。EBNA-2的自结合可能是EBNA-2通过其与细胞DNA结合蛋白的相互作用域及其酸性激活域同时与多种细胞转录因子和共激活因子相互作用的关键。, 2001)。(3)通过酵母双杂交筛选，我们在酵母和人淋巴细胞中发现了与EBNA-LP相关的HAX-1蛋白。据报道，HAX-1是一种位于线粒体中的细胞质蛋白，与B细胞受体相关激酶的底物HS1相关。

Epstein-Barr virus (EBV) infection causes cell growth transformation of primary human B lymphocyte. EBV nuclear proteins EBNA-2 and EBNA-LP play critical roles on the transformation. Those proteins are expressed simultaneously in early stage of EBV infection. EBNA-2 is a transactivator that up-regulates transcriptional activities of both viral and cellular promoters. EBNA-LP stimulates the EBNA-2 mediated transactivation as a cofactor (Harada a ＆ Kieff, J.Virol., 1997). To address the molecular mechanism of transcriptional activation which EBNA-2 and EBNA-LP cooperatively regulate to establish the EBV latent infection, we investigate direct and indirect interaction of those EBNAs, and the association of EBNA-LP with cellular proteins.(1) EBNA-LP-associated proteins were identified by sequencing proteins that immunoprecipitated with flag-tagged EBNA-LP from B lymphoblast cells in which flag-LP was stably expressed. The association of EBNA-LP with Hsp70 (72/73) was confirmed, and sequences of DNA-PK catalytic subunit, HA95, Hsp27, prolyl 4-hydroxylase α-1 subunit, α-tublin, β-tublin, were identified (J.Virol., 2001b).(2) EBNA-2 has at least two domains, amino acids 1 to 60 and 96 to 210, which independently mediate homotypic association. EBNA-2 self-association is likely to be critical to the ability of EBNA-2 to interact simultaneously with multiple cellular transcription factors and coactivators through its interaction domain to cellular DNA binding proteins and its acidic activation domain (J.Virol., 2001a).(3) We identified HAX-1 protein that associates with EBNA-LP in both yeast and human lymphocytes using the yeast two-hybrid screening. HAX-1 is reported to be a cytoplasmic protein that locates in mitochondria and associates with HS1 that is a substrate of B cell receptor associated kinase.