Wood C David, Veenstra Hildegonda, Khasnis Sarika, Gunnell Andrea, Webb Helen M, Shannon-Lowe Claire, Andrews Simon, Osborne Cameron S, West Michelle J
School of Life Sciences, University of Sussex, Brighton, United Kingdom.
Institute of Immunology and Immunotherapy, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom.
Elife. 2016 Aug 4;5:e18270. doi: 10.7554/eLife.18270.
Lymphomagenesis in the presence of deregulated MYC requires suppression of MYC-driven apoptosis, often through downregulation of the pro-apoptotic BCL2L11 gene (Bim). Transcription factors (EBNAs) encoded by the lymphoma-associated Epstein-Barr virus (EBV) activate MYC and silence BCL2L11. We show that the EBNA2 transactivator activates multiple MYC enhancers and reconfigures the MYC locus to increase upstream and decrease downstream enhancer-promoter interactions. EBNA2 recruits the BRG1 ATPase of the SWI/SNF remodeller to MYC enhancers and BRG1 is required for enhancer-promoter interactions in EBV-infected cells. At BCL2L11, we identify a haematopoietic enhancer hub that is inactivated by the EBV repressors EBNA3A and EBNA3C through recruitment of the H3K27 methyltransferase EZH2. Reversal of enhancer inactivation using an EZH2 inhibitor upregulates BCL2L11 and induces apoptosis. EBV therefore drives lymphomagenesis by hijacking long-range enhancer hubs and specific cellular co-factors. EBV-driven MYC enhancer activation may contribute to the genesis and localisation of MYC-Immunoglobulin translocation breakpoints in Burkitt's lymphoma.
在MYC失调的情况下发生淋巴瘤生成需要抑制MYC驱动的细胞凋亡,通常是通过下调促凋亡的BCL2L11基因(Bim)来实现。淋巴瘤相关的爱泼斯坦-巴尔病毒(EBV)编码的转录因子(EBNAs)激活MYC并使BCL2L11沉默。我们发现EBNA2反式激活因子激活多个MYC增强子并重新配置MYC基因座,以增加上游并减少下游增强子-启动子相互作用。EBNA2将SWI/SNF重塑复合物的BRG1 ATP酶招募到MYC增强子,并且BRG1是EBV感染细胞中增强子-启动子相互作用所必需的。在BCL2L11基因处,我们鉴定出一个造血增强子枢纽,EBV阻遏蛋白EBNA3A和EBNA3C通过招募H3K27甲基转移酶EZH2使其失活。使用EZH2抑制剂逆转增强子失活可上调BCL2L11并诱导细胞凋亡。因此,EBV通过劫持远程增强子枢纽和特定的细胞辅因子来驱动淋巴瘤生成。EBV驱动的MYC增强子激活可能有助于伯基特淋巴瘤中MYC-免疫球蛋白易位断点的产生和定位。