Epigenetic repression of p16(INK4A) by latent Epstein-Barr virus requires the interaction of EBNA3A and EBNA3C with CtBP.
As an inhibitor of cyclin-dependent kinases, p16(INK4A) is an important tumour suppressor and inducer of cellular senescence that is often inactivated during the development of cancer by promoter DNA methylation. Using newly established lymphoblastoid cell lines (LCLs) expressing a conditional EBNA3C from recombinant EBV, we demonstrate that EBNA3C inactivation initiates chromatin remodelling that resets the epigenetic status of p16(INK4A) to permit transcriptional activation: the polycomb-associated repressive H3K27me3 histone modification is substantially reduced, while the activation-related mark H3K4me3 is modestly increased. Activation of EBNA3C reverses the distribution of these epigenetic marks, represses p16(INK4A) transcription and allows proliferation. LCLs lacking EBNA3A express relatively high levels of p16(INK4A) and have a similar pattern of histone modifications on p16(INK4A) as produced by the inactivation of EBNA3C. Since binding to the co-repressor of transcription CtBP has been linked to the oncogenic activity of EBNA3A and EBNA3C, we established LCLs with recombinant viruses encoding EBNA3A- and/or EBNA3C-mutants that no longer bind CtBP. These novel LCLs have revealed that the chromatin remodelling and epigenetic repression of p16(INK4A) requires the interaction of both EBNA3A and EBNA3C with CtBP. The repression of p16(INK4A) by latent EBV will not only overcome senescence in infected B cells, but may also pave the way for p16(INK4A) DNA methylation during B cell lymphomagenesis.
Skalska
Lenka
L
Section of Virology, Division of Infectious Diseases, Faculty of Medicine, Imperial College London, London, United Kingdom.
White
Robert E
RE
Franz
Melanie
M
Ruhmann
Michaela
M
Allday
Martin J
MJ
D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D000956:Antigens, Viral / Q000235:genetics / Q000378:metabolism*; D001402:B-Lymphocytes / Q000378:metabolism / Q000473:pathology; D015153:Blotting, Western; D049109:Cell Proliferation; D042002:Chromatin Assembly and Disassembly; D047369:Chromatin Immunoprecipitation; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics* / Q000378:metabolism; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D044127:Epigenesis, Genetic; D020031:Epstein-Barr Virus Infections / Q000235:genetics / Q000378:metabolism*; D019309:Epstein-Barr Virus Nuclear Antigens / Q000235:genetics / Q000378:metabolism*; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015533:Transcriptional Activation
D000956:Antigens, Viral; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004268:DNA-Binding Proteins; C508151:EBNA-3A antigen; C498774:EBNA-3C, epstein-barr virus; D019309:Epstein-Barr Virus Nuclear Antigens; D012333:RNA, Messenger; D000429:Alcohol Oxidoreductases; C096794:C-terminal binding protein