Identification and characterization of a novel spliced form of the meq transcript in lymphoblastoid cell lines derived from Marek's disease tumours.
In tumour cell lines established from Marek's disease (MD) lymphomas L-meq is consistently expressed. It contains a 180 bp insertion encoding additional copies of the proline-rich repeat in the meq open reading frame and its product may contribute to the maintenance of MD virus (MDV) latency. In this study, we identified a novel spliced form of the meq transcript in MD-derived lymphoblastoid cell lines and in MDV-infected cells. This transcript, termed Deltameq, encodes an N-terminal 98 aa of the Meq protein and lacks part of the basic leucine zipper (bZIP) and transactivation domains. In MD cell lines, transcription of L-meq was significantly downregulated, while that of the Deltameq transcript was upregulated during apoptosis. These observations were also confirmed at the protein expression level. Reporter assays using meq- and interleukin-2 (IL-2)-promoter-driven luciferase vectors revealed that DeltaMeq suppressed transactivation by L-Meq or Meq in a dose-dependent manner. Immunoprecipitation confirmed that DeltaMeq was associated with L-Meq or Meq physically. These results suggest that DeltaMeq could be involved in apoptosis in MD cell lines as it works as a negative regulator of L-Meq and Meq by direct interaction.
Okada
Tsukasa
T
Department of Microbiology and Immunology, Faculty of Agriculture, Kobe University, 1-1, Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan.|Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Kita-18, Nishi-9, Kita-ku, Sapporo 060-0818, Japan.
Takagi
Michihiro
M
Department of Microbiology and Immunology, Faculty of Agriculture, Kobe University, 1-1, Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan.
Murata
Shiro
S
Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Kita-18, Nishi-9, Kita-ku, Sapporo 060-0818, Japan.
Onuma
Misao
M
Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Kita-18, Nishi-9, Kita-ku, Sapporo 060-0818, Japan.
Ohashi
Kazuhiko
K
Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Kita-18, Nishi-9, Kita-ku, Sapporo 060-0818, Japan.
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D002460:Cell Line / Q000502:physiology / Q000821:virology; D002642:Chick Embryo; D015967:Gene Expression Regulation, Viral; D006801:Humans; D025922:Mardivirus / Q000502:physiology*; D008380:Marek Disease / Q000821:virology*; D008969:Molecular Sequence Data; D009856:Oncogene Proteins, Viral / Q000235:genetics* / Q000378:metabolism; D016366:Open Reading Frames / Q000235:genetics; D012326:RNA Splicing; D016415:Sequence Alignment; D015533:Transcriptional Activation; D017735:Virus Latency
C100369:Eco-Q protein, Gallid herpesvirus 2; D009856:Oncogene Proteins, Viral