Schmidt Stefanie C S, Jiang Sizun, Zhou Hufeng, Willox Bradford, Holthaus Amy M, Kharchenko Peter V, Johannsen Eric C, Kieff Elliott, Zhao Bo
Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115; Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115;
Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115;
Proc Natl Acad Sci U S A. 2015 Jan 13;112(2):554-9. doi: 10.1073/pnas.1422580112. Epub 2014 Dec 24.
Epstein-Barr Virus (EBV) conversion of B-lymphocytes to Lymphoblastoid Cell Lines (LCLs) requires four EBV nuclear antigen (EBNA) oncoproteins: EBNA2, EBNALP, EBNA3A, and EBNA3C. EBNA2 and EBNALP associate with EBV and cell enhancers, up-regulate the EBNA promoter, MYC, and EBV Latent infection Membrane Proteins (LMPs), which up-regulate BCL2 to protect EBV-infected B-cells from MYC proliferation-induced cell death. LCL proliferation induces p16(INK4A) and p14(ARF)-mediated cell senescence. EBNA3A and EBNA3C jointly suppress p16(INK4A) and p14(ARF), enabling continuous cell proliferation. Analyses of the EBNA3A human genome-wide ChIP-seq landscape revealed 37% of 10,000 EBNA3A sites to be at strong enhancers; 28% to be at weak enhancers; 4.4% to be at active promoters; and 6.9% to be at weak and poised promoters. EBNA3A colocalized with BATF-IRF4, ETS-IRF4, RUNX3, and other B-cell Transcription Factors (TFs). EBNA3A sites clustered into seven unique groups, with differing B-cell TFs and epigenetic marks. EBNA3A coincidence with BATF-IRF4 or RUNX3 was associated with stronger EBNA3A ChIP-Seq signals. EBNA3A was at MYC, CDKN2A/B, CCND2, CXCL9/10, and BCL2, together with RUNX3, BATF, IRF4, and SPI1. ChIP-re-ChIP revealed complexes of EBNA3A on DNA with BATF. These data strongly support a model in which EBNA3A is tethered to DNA through a BATF-containing protein complexes to enable continuous cell proliferation.
爱泼斯坦-巴尔病毒（EBV）将B淋巴细胞转化为淋巴母细胞系（LCLs）需要四种EBV核抗原（EBNA）癌蛋白：EBNA2、EBNALP、EBNA3A和EBNA3C。EBNA2和EBNALP与EBV和细胞增强子结合，上调EBNA启动子、MYC和EBV潜伏感染膜蛋白（LMPs），后者上调BCL2以保护EBV感染的B细胞免受MYC增殖诱导的细胞死亡。LCL增殖诱导p16（INK4A）和p14（ARF）介导的细胞衰老。EBNA3A和EBNA3C共同抑制p16（INK4A）和p14（ARF），使细胞能够持续增殖。对EBNA3A全基因组ChIP-seq图谱的分析显示，在10000个EBNA3A位点中，37%位于强增强子处；28%位于弱增强子处；4.4%位于活性启动子处；6.9%位于弱且处于准备状态的启动子处。EBNA3A与BATF-IRF4、ETS-IRF4、RUNX3和其他B细胞转录因子（TFs）共定位。EBNA3A位点聚集成七个独特的组，具有不同的B细胞TFs和表观遗传标记。EBNA3A与BATF-IRF4或RUNX3的重合与更强的EBNA3A ChIP-Seq信号相关。EBNA3A位于MYC、CDKN2A/B、CCND2、CXCL9/10和BCL2处，同时还有RUNX3、BATF、IRF4和SPI1。ChIP-re-ChIP揭示了EBNA3A与BATF在DNA上形成的复合物。这些数据有力地支持了一个模型，即EBNA3A通过含BATF的蛋白质复合物与DNA相连，从而使细胞能够持续增殖。
