title: Symmetrical localization of extrachromosomally replicating viral genomes on sister chromatids.
abstract: 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.
authors.affiliation: Center for Virus Vector Development, Institute for Genetic Medicine, Hokkaido University, Sapporo 060-0815, Japan. tkanda@igm.hokudai.ac.jp
authors.forename: Teru
authors.initials: T
authors.lastname: Kanda
authors.forename: Masato
authors.initials: M
authors.lastname: Kamiya
authors.forename: Seiji
authors.initials: S
authors.lastname: Maruo
authors.forename: Dai
authors.initials: D
authors.lastname: Iwakiri
authors.forename: Kenzo
authors.initials: K
authors.lastname: Takada
mesh_terms: D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000737:chemistry / Q000235:genetics; D002842:Chromatids / Q000235:genetics*; D002868:Chromosomal Proteins, Non-Histone / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D004261:DNA Replication / Q000235:genetics*; D054659:Diketopiperazines; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019309:Epstein-Barr Virus Nuclear Antigens / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D016195:G2 Phase / Q000235:genetics; D018628:Gene Dosage; D016679:Genome, Viral; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D004854:Herpesvirus 4, Human / Q000235:genetics*; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D017404:In Situ Hybridization, Fluorescence; D008387:Marine Toxins; D008938:Mitosis / Q000187:drug effects; D008957:Models, Genetic; D010080:Oxazoles / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D010957:Plasmids / Q000032:analysis / Q000235:genetics*; D059005:Topoisomerase II Inhibitors
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D054659:Diketopiperazines; D004791:Enzyme Inhibitors; D019309:Epstein-Barr Virus Nuclear Antigens; D008387:Marine Toxins; D010080:Oxazoles; D010879:Piperazines; D059005:Topoisomerase II Inhibitors; C060905:centromere protein C; D049452:Green Fluorescent Proteins; C070899:4,4'-(1,2-dimethyl-1,2-ethanediyl)bis-2,6-piperazinedione; C059041:calyculin A; C417029:EBV-encoded nuclear antigen 1; D006918:Hydroxyurea