title: The insulator protein CTCF binding sites in the orf73/LANA promoter region of herpesvirus saimiri are involved in conferring episomal stability in latently infected human T cells.
abstract: Herpesviruses establish latency in suitable cells of the host organism after a primary lytic infection. Subgroup C strains of herpesvirus saimiri (HVS), a primate gamma-2 herpesvirus, are able to transform human and other primate T lymphocytes to stable growth in vitro. The viral genomes persist as nonintegrated, circular, and histone-associated episomes in the nuclei of those latently infected T cells. Epigenetic modifications of episomes are essential to restrict the transcription during latency to selected viral genes, such as the viral oncogenes stpC/tip and the orf73/LANA. In this study, we describe a genome-wide chromatin immunoprecipitation-on-chip (ChIP-on-chip) analysis to profile the occupancy of CTCF on the latent HVS genome. We then focused on two distinct, conserved CTCF binding sites (CBS) within the orf73/LANA promoter region. Analysis of recombinant viruses harboring deletions or mutations within the CBS indicated that the lytic replication of such viruses is not substantially influenced by CTCF. However, T cells latently infected with CBS mutants were impaired in their proliferation abilities and showed a significantly reduced episomal maintenance. We detected a reduced transcription of the orf73/LANA gene in the T cells, corresponding to the reduced viral genomes; this might contribute to the loss of HVS episomes, as LANA is central in the maintenance of viral episomes in the dividing T cell populations. These data demonstrate that the episomal stability of HVS genomes in latently infected human T cells is dependent on CTCF.
authors: Institut für Klinische und Molekulare Virologie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.
authors: Katrin
authors: K
authors: Zielke
authors: Florian
authors: F
authors: Full
authors: Natascha
authors: N
authors: Teufert
authors: Monika
authors: M
authors: Schmidt
authors: Ingrid
authors: I
authors: Müller-Fleckenstein
authors: Barbara
authors: B
authors: Alberter
authors: Armin
authors: A
authors: Ensser
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D000076246:CCCTC-Binding Factor; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D022202:Chromosomes, Artificial, Bacterial; D017931:DNA Primers; D006567:Herpesvirus 2, Saimiriine / Q000235:genetics* / Q000502:physiology; D006801:Humans; D016366:Open Reading Frames; D010957:Plasmids / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000378:metabolism*; D013601:T-Lymphocytes / Q000821:virology*; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism; D017735:Virus Latency
chemical_list: D000076246:CCCTC-Binding Factor; C000619697:CTCF protein, human; D017931:DNA Primers; D012097:Repressor Proteins; D014764:Viral Proteins