CTCF and Sp1 interact with the Murine gammaherpesvirus 68 internal repeat elements.
Herpesviruses maintain a dynamic balance between latency and productive infection. This is a complex process regulated by viral and cellular factors. We have developed a Murine gammaherpesvirus 68 (MHV-68) model system in which to study mechanisms underlying balance between latency and lytic infection. We have generated an epithelial cell line that carries MHV-68 in a tightly latent form by using a bacterial artificial chromosome clone of the virus genome with a mutation in the MHV-68 major lytic R transactivator gene. Complementation of this defect in                         trans by transfection with a plasmid encoding R transactivator initiated and restored the productive cycle. This cell line model was used to investigate transcription factor occupancy (CCCTC binding factor [CTCF] and Sp1) of the two internal repeat elements in the viral genome during latency and reactivation using chromatin immunoprecipitation. Our results show that CTCF can bind to the 40-bp and the 100-bp repeat sequences during latency, whereas binding is reduced upon reactivation. In contrast, Sp1 only bound to the 100-bp repeat after reactivation. Our results indicate that the large internal repeat sequences in MHV-68 have different functions. We hypothesise that the 40-bp repeat may be involved in regulation of gene expression during the maintenance of latency, while the 100-bp repeat domain may be involved in regulation of the lytic cycle.
Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, L69 3GE, UK.
Hannah C
HC
Stevens
Kevin S-W
KS
Cham
David J
DJ
Hughes
Ren
R
Sun
Jeffery T
JT
Sample
Vivien J
VJ
Bubb
James P
JP
Stewart
John P
JP
Quinn
D000818:Animals; D001483:Base Sequence; D000076246:CCCTC-Binding Factor; D047369:Chromatin Immunoprecipitation; D004279:DNA, Viral / Q000378:metabolism*; D004847:Epithelial Cells / Q000821:virology; D054884:Host-Pathogen Interactions; D051379:Mice; D008969:Molecular Sequence Data; D011485:Protein Binding; D012091:Repetitive Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000378:metabolism*; D018144:Rhadinovirus / Q000235:genetics / Q000502:physiology*; D016329:Sp1 Transcription Factor / Q000378:metabolism*
D000076246:CCCTC-Binding Factor; C000619698:Ctcf protein, mouse; D004279:DNA, Viral; D012097:Repressor Proteins; D016329:Sp1 Transcription Factor