Spender L C, Cornish G H, Rowland B, Kempkes B, Farrell P J
Ludwig Institute for Cancer Research, Imperial College School of Medicine, London W2 1PG, United Kingdom.
J Virol. 2001 Apr;75(8):3537-46. doi: 10.1128/JVI.75.8.3537-3546.2001.
We have studied the pathways of regulation of cytokine and cell cycle control proteins during infection of human B lymphocytes by Epstein-Barr virus (EBV). Among 30 cytokine RNAs analyzed by the RNase protection assay, tumor necrosis factor alpha (TNF-alpha), granulocyte colony-stimulating factor, lymphotoxin (LT), and LTbeta were found to be regulated within 20 h of EBV infection of primary B cells. Similar results were obtained using the estrogen-regulated EBNA-2 cell line EREB2.5, in which RNAs for LT and TNF-alpha were induced within 6 h of activation of EBNA-2. Expression of Notch also caused an induction of TNF-alpha RNA. The induction of TNF-alpha RNA by EBNA-2 was indirect, and constitutive expression of either LMP-1 or c-myc proteins did not substitute for EBNA-2 in induction of TNF-alpha RNA. Cyclin D2 is also an indirect target of EBNA-2-mediated transactivation. EBNA-2 was found to activate the cyclin D2 promoter in a transient-transfection assay. A mutant of EBNA-2 that does not bind RBP-Jkappa retained some activity in this assay, and activation did not depend on the presence of B-cell-specific factors. Deletion analysis of the cyclin D2 promoter revealed that removal of sequences containing E-box c-myc consensus DNA binding sequences did not reduce EBNA-2-mediated activation of the cyclin D2 promoter in the transient-transfection assay. The results indicate that cytokines are an early target of EBNA-2 and that EBNA-2 can regulate cyclin D2 transcription in EBV-infected cells by mechanisms additional to the c-myc pathway.
我们研究了爱泼斯坦-巴尔病毒（EBV）感染人B淋巴细胞过程中细胞因子和细胞周期调控蛋白的调节途径。在用核糖核酸酶保护试验分析的30种细胞因子RNA中，发现肿瘤坏死因子α（TNF-α）、粒细胞集落刺激因子、淋巴毒素（LT）和LTβ在EBV感染原代B细胞的20小时内受到调节。使用雌激素调节的EBNA-2细胞系EREB2.5也获得了类似结果，其中LT和TNF-α的RNA在EBNA-2激活后的6小时内被诱导。Notch的表达也导致TNF-α RNA的诱导。EBNA-2对TNF-α RNA的诱导是间接的，LMP-1或c-myc蛋白的组成型表达在诱导TNF-α RNA时不能替代EBNA-2。细胞周期蛋白D2也是EBNA-2介导的反式激活的间接靶点。在瞬时转染试验中发现EBNA-2可激活细胞周期蛋白D2启动子。一种不与RBP-Jκ结合的EBNA-2突变体在该试验中仍保留一些活性，且激活不依赖于B细胞特异性因子的存在。对细胞周期蛋白D2启动子的缺失分析表明，在瞬时转染试验中，去除含有E-box c-myc共有DNA结合序列的序列并不会降低EBNA-2介导的细胞周期蛋白D2启动子的激活。结果表明，细胞因子是EBNA-2的早期靶点，并且EBNA-2可通过c-myc途径以外的机制调节EBV感染细胞中细胞周期蛋白D2的转录。
