Cell cycle control of Kaposi's sarcoma-associated herpesvirus latency transcription by CTCF-cohesin interactions

J Virol. 2009 Jun;83(12):6199-210. doi: 10.1128/JVI.00052-09. Epub 2009 Apr 15.

Abstract

Kaposi's sarcoma-associated herpesvirus (KSHV) latency is characterized by the highly regulated transcription of a few viral genes essential for genome maintenance and host cell survival. A major latency control region has been identified upstream of the divergent promoters for the multicistronic transcripts encoding LANA (ORF73), vCyclin (ORF72), and vFLIP (ORF71) and for the complementary strand transcript encoding K14 and vGPCR (ORF74). Previous studies have shown that this major latency control region is occupied by the cellular chromatin boundary factor CTCF and chromosome structural maintenance proteins SMC1, SMC3, and RAD21, which comprise the cohesin complex. Deletion of the CTCF-cohesin binding site caused an inhibition of cell growth and viral genome instability. We now show that the KSHV genes regulated by CTCF-cohesin are under cell cycle control and that mutation of the CTCF binding sites abolished cell cycle-regulated transcription. Cohesin subunits assembled at the CTCF binding sites and bound CTCF proteins in a cell cycle-dependent manner. Subcellular distribution of CTCF and colocalization with cohesins also varied across the cell cycle. Ectopic expression of Rad21 repressed CTCF-regulated transcription of KSHV lytic genes, and a Rad21-CTCF chimeric protein converted CTCF into an efficient transcriptional repressor of KSHV genes normally activated in the G(2) phase. We conclude that cohesins interact with CTCF in mid-S phase and repress CTCF-regulated genes in a cell cycle-dependent manner. We propose that the CTCF-cohesin complex plays a critical role in regulating the cell cycle control of viral gene expression during latency and that failure to maintain cell cycle control of latent transcripts inhibits host cell proliferation and survival.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • CCCTC-Binding Factor
  • Cell Cycle Proteins / metabolism*
  • Cell Cycle*
  • Cell Line
  • Chromosomal Proteins, Non-Histone / metabolism*
  • Cohesins
  • DNA-Binding Proteins / metabolism*
  • Gene Expression Profiling
  • Gene Expression Regulation, Viral
  • Genes, Viral
  • Herpesvirus 8, Human / genetics
  • Herpesvirus 8, Human / physiology*
  • Humans
  • Nuclear Proteins / metabolism
  • Phosphoproteins / metabolism
  • RNA Splicing
  • RNA, Messenger / metabolism
  • RNA, Viral / metabolism
  • Repressor Proteins / metabolism*
  • Transcription, Genetic
  • Virus Latency / genetics*

Substances

  • CCCTC-Binding Factor
  • CTCF protein, human
  • Cell Cycle Proteins
  • Chromosomal Proteins, Non-Histone
  • DNA-Binding Proteins
  • Nuclear Proteins
  • Phosphoproteins
  • RAD21 protein, human
  • RNA, Messenger
  • RNA, Viral
  • Repressor Proteins