Methylation of discrete sites within the enhancer region regulates the activity of the Epstein-Barr virus BamHI W promoter in Burkitt lymphoma lines.
Methylation of discrete sites within the enhancer region regulates the activity of the Epstein-Barr virus BamHI W promoter in Burkitt lymphoma lines.
复制标题
增强子区域内离散位点的甲基化调节伯基特淋巴瘤系中 Epstein-Barr 病毒 BamHI W 启动子的活性。
DOI：
10.1128/jvi.66.1.62-69.1992
复制
发表时间：
1992
影响因子：
5.4
通讯作者：
Rymo,L
中科院分区：
文献类型：
--
作者：
Jansson,A;Masucci,M;Rymo,L
已知在体外EB病毒（EBV）转化的B淋巴母细胞系中表达的9种病毒抗原中有8种在携带EBV的伯基特淋巴瘤（BL）中下调。在体外培养期间保持代表性表型的BL活检和BL衍生的细胞系（I组BL系）中仅可检测到EBNA1。这种病毒基因表达的限制模式伴随着广泛的EBV DNA甲基化，并且可以通过用去甲基化剂5-氮杂胞苷治疗来逆转。编码六种转化相关EBNA的基因的转录可以从分别位于病毒基因组的BamHI C和W区的两个启动子之一启动。我们发现，在BamHI W增强子区域内的离散位点在组I BL系Rael、Cheptage和Elijah中被甲基化，并且在5-氮杂胞苷处理诱导EBNA2表达后变得未甲基化。去甲基化与BamHI W启动子的转录激活相关，如通过S1保护分析所确定的。其中W增强子序列连接到氯霉素乙酰转移酶基因的报告质粒在未处理的Rael、Cheptage和Elijah细胞中是活跃的，表明所有所需的转录因子都存在于I组BL细胞中。相反，增强子序列的体外甲基化消除了它们的活性。结果表明，EBV基因组中控制区域的甲基化可能在肿瘤细胞中病毒基因表达的调节中起关键作用。
Eight of the nine viral antigens known to be expressed in in vitro Epstein-Barr virus (EBV)-transformed B-lymphoblastoid cell lines are downregulated in EBV-carrying Burkitt lymphomas (BL). Only EBNA1 can be detected in BL biopsies and BL-derived cell lines that maintain the representative phenotype during culture in vitro (group I BL lines). This restricted pattern of viral gene expression is accompanied by extensive EBV DNA methylation and can be reversed by treatment with the demethylating agent 5-azacytidine. Transcription of the genes encoding the six transformation-associated EBNAs can be initiated from one of two promoters located in the BamHI C and W regions, respectively, of the virus genome. We show that discrete sites within the BamHI W enhancer region are methylated in the group I BL lines Rael, Cheptage, and Elijah and become unmethylated after 5-azacytidine treatment that induces the expression of EBNA2. Demethylation correlates with activation of transcription from the BamHI W promoter as determined by S1 protection analysis. Reporter plasmids in which the W enhancer sequences were linked to the chloramphenicol acetyltransferase gene were active in untreated Rael, Cheptage, and Elijah cells, demonstrating that all of the required transcription factors are present in group I BL cells. Conversely, in vitro methylation of the enhancer sequences abolished their activity. The results suggest that methylation of control regions in the EBV genome may play a critical role for the regulation of viral gene expression in tumor cells.