Quantitative analysis of the bidirectional viral G-protein-coupled receptor and lytic latency-associated nuclear antigen promoter of Kaposi's sarcoma-associated herpesvirus

J Virol. 2012 Sep;86(18):9683-95. doi: 10.1128/JVI.00881-12. Epub 2012 Jun 27.

Abstract

Kaposi's sarcoma-associated herpesvirus (KSHV) establishes sustained latent persistence in susceptible cells. This is dependent on the latency-associated nuclear antigen (LANA). Understanding how LANA transcription is regulated thus aids our fundamental understanding of KSHV biology. Two hundred ninety-four base pairs are sufficient to regulate LANA transcription in response to the viral RTA protein and RBPjκ. The same region controls K14/viral G-protein-coupled receptor (vGPCR) transcription in the opposite direction. We used a quantitative analysis in conjunction with specific nucleotide substitutions and defined gain-of-function and loss-of-function RTA mutants to dissect this region. We used a bidirectional reporter driving red and green luciferase to study the LANApi and K14p promoters simultaneously. This established that LANApi/K14p functions as a canonical bidirectional promoter. Both were TATA dependent. K14p was favored by ∼50-fold in this context. Eliminating the distal LANApi TATA box increased maximal output and lowered the induction threshold (T) of K14p even further. Two RBPjκ binding sites were independently required; however, at high concentrations of RTA, direct interactions with an RTA-responsive element (RRE) could complement the loss of one RBPjκ binding site. Intracellular Notch (ICN) was no longer able to activate RBPjκ in the viral context. This suggests a model whereby KSHV alters ICN-RBPjκ gene regulation. When the architecture of this pair of head-to-head RBPjκ binding sites is changed, the sites now respond exclusively to the viral transactivator RTA and no longer to the host mediator ICN.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Antigens, Viral / genetics*
  • Antigens, Viral / physiology*
  • Base Sequence
  • Cell Line
  • Genome, Viral
  • Herpesvirus 8, Human / genetics*
  • Herpesvirus 8, Human / immunology
  • Herpesvirus 8, Human / pathogenicity
  • Herpesvirus 8, Human / physiology*
  • Host-Pathogen Interactions / genetics
  • Host-Pathogen Interactions / physiology
  • Humans
  • Immediate-Early Proteins / genetics
  • Immediate-Early Proteins / physiology
  • Models, Biological
  • Molecular Sequence Data
  • Mutation
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / physiology*
  • Promoter Regions, Genetic
  • RNA, Messenger / genetics
  • RNA, Viral / genetics
  • Receptors, G-Protein-Coupled / genetics
  • Receptors, G-Protein-Coupled / physiology*
  • Receptors, Virus / genetics
  • Receptors, Virus / physiology*
  • Trans-Activators / genetics
  • Trans-Activators / physiology
  • Virus Latency / genetics
  • Virus Latency / physiology

Substances

  • Antigens, Viral
  • Immediate-Early Proteins
  • Nuclear Proteins
  • RNA, Messenger
  • RNA, Viral
  • Receptors, G-Protein-Coupled
  • Receptors, Virus
  • Rta protein, Human herpesvirus 8
  • Trans-Activators
  • latency-associated nuclear antigen