Symmetrical localization of extrachromosomally replicating viral genomes on sister chromatids
Symmetrical localization of extrachromosomally replicating viral genomes on sister chromatids
复制标题
DOI：
10.1242/jcs.03434
复制
发表时间：
2007-05-01
影响因子：
4
通讯作者：
Takada, Kenzo
中科院分区：
文献类型：
--
作者：
Kanda, Teru;Kamiya, Masato;Takada, Kenzo
在真核生物中，许多潜伏的病毒以染色体外分子的形式复制，被称为附着体，并通过非共价附着在有丝分裂染色体上而有效地分离到子细胞。为了了解控制这些过程的机制，我们分析了EB病毒(EBV)基因组和病毒蛋白EBNA1的详细亚细胞定位，EBNA1是病毒基因组和细胞染色质之间的桥梁分子。在表达表位标记的EBNA1的重组EBV感染细胞中，EBNA1定位于核内斑点，这与荧光原位杂交(FISH)显示的EBV基因组定位一致。在有丝分裂染色体的姐妹染色单体上发现了大量对称分布的EBNA1点。在过早浓缩的G2染色体中也观察到了EBNA1点的这种对称定位，这与G2期浓缩细胞中EBNA1的紧密间隔的双点的存在有关。EBNA1双点偶尔被EBV附体的FISH信号连接在一起，呈现哑铃状外观。因此，我们认为，在细胞DNA复制过程中，EBNA1分子在姐妹染色单体上的分割是染色体外复制病毒基因组非随机分离的基础。
In eukaryotes, many latent viruses replicate as extrachromosomal molecules, called episomes, and efficiently segregate to daughter cells by noncovalently attaching to mitotic chromosomes. To understand the mechanism governing the processes, we analyzed the detailed subcellular localization of Epstein-Barr virus (EBV) genomes and a viral protein EBNA1, a bridging molecule between viral genomes and cellular chromatin. In the cells that were infected with a recombinant EBV expressing epitope-tagged EBNA1, EBNA1 localized to intranuclear punctate dots, which coincided with the localization of EBV genomes as revealed by fluorescence in situ hybridization (FISH). A significant number of EBNA1 dots were found to localize symmetrically on sister chromatids of mitotic chromosomes. Such symmetrical localization of EBNA1 dots was observed in prematurely condensed G2 chromosomes as well, correlating with the presence of closely spaced double dots of EBNA1 in G2-phase-enriched cells. The EBNA1 double dots were occasionally interconnected by the FISH signals of EBV episomes, exhibiting a dumbbell-like appearance. Thus, we propose that the partitioning of EBNA1 molecules onto sister chromatids during cellular DNA replication underlies the non-stochastic segregation of extrachromosomally replicating viral genomes.