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

EB病毒核蛋白EBNA-LP共激活活性的分子机制

基本信息

批准号：
11670289
负责人：
HARADA Shizuko
金额：
$ 2.3万
依托单位：
ST.MARIANNA UNIVERSITY SCHOOL OF MEDICINE (2000)Kanazawa University (1999)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

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.

EB病毒（Epstein-Barr virus，EBV）感染引起人原代B淋巴细胞的细胞生长转化。EB病毒核蛋白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是上调病毒和细胞启动子的转录活性的反式激活因子。EBNA-LP刺激作为辅因子的EBNA-2介导的反式激活（Harada a & Kieff，J.Virol.，1997年）。为了阐明EBNA-2和EBNA-LP协同调节转录激活以建立EBV潜伏感染的分子机制，我们研究了这些EBNA的直接和间接相互作用，以及EBNA-LP与细胞蛋白的关联。(1)EBNA-LP相关蛋白通过测序与来自稳定表达flag-LP的B淋巴母细胞的flag-taged EBNA-LP免疫沉淀的蛋白来鉴定。EBNA-LP与Hsp 70（72/73）的相关性得到证实，并鉴定了DNA-PK催化亚基、HA 95、Hsp 27、脯氨酰4-羟化酶α-1亚基、α-tublin、β-tublin的序列（J.Virol.，2001年b）。(2)EBNA-2具有至少两个结构域，氨基酸1至60和96至210，其独立地介导同型结合。EBNA-2自缔合可能对EBNA-2通过其与细胞DNA结合蛋白的相互作用结构域及其酸性活化结构域同时与多种细胞转录因子和共活化因子相互作用的能力至关重要（J.Virol.，2001年a）。(3)我们使用酵母双杂交筛选在酵母和人淋巴细胞中鉴定了与EBNA-LP相关的HAX-1蛋白。据报道HAX-1是位于线粒体中的胞质蛋白，并且与作为B细胞受体相关激酶的底物的HS 1缔合。