Np95 interacts with de novo DNA methyltransferases, Dnmt3a and Dnmt3b, and mediates epigenetic silencing of the viral CMV promoter in embryonic stem cells.
Recent studies have indicated that nuclear protein of 95 kDa (Np95) is essential for maintaining genomic methylation by recruiting DNA methyltransferase (Dnmt) 1 to hemi-methylated sites. Here, we show that Np95 interacts more strongly with regulatory domains of the de novo methyltransferases Dnmt3a and Dnmt3b. To investigate possible functions, we developed an epigenetic silencing assay using fluorescent reporters in embryonic stem cells (ESCs). Interestingly, silencing of the cytomegalovirus promoter in ESCs preceded DNA methylation and was strictly dependent on the presence of either Np95, histone H3 methyltransferase G9a or Dnmt3a and Dnmt3b. Our results indicate a regulatory role for Np95, Dnmt3a and Dnmt3b in mediating epigenetic silencing through histone modification followed by DNA methylation.
Department of Biology II, Center for Integrated Protein Science Munich (CIPSM), Ludwig Maximilians University Munich, Grosshaderner Street 2, 82152 Planegg-Martinsried, Germany.
Daniela
D
Meilinger
Karin
K
Fellinger
Sebastian
S
Bultmann
Ulrich
U
Rothbauer
Ian Marc
IM
Bonapace
Wolfgang E F
WE
Klinkert
Fabio
F
Spada
Heinrich
H
Leonhardt
D000818:Animals; D022762:CCAAT-Enhancer-Binding Proteins / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D003587:Cytomegalovirus / Q000235:genetics*; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism*; D019175:DNA Methylation; D000090205:DNA Methyltransferase 3A; D053595:Embryonic Stem Cells / Q000166:cytology*; D044127:Epigenesis, Genetic; D020868:Gene Silencing; D006801:Humans; D008780:Methyltransferases / Q000737:chemistry; D051379:Mice; D009687:Nuclear Proteins / Q000737:chemistry*; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D044767:Ubiquitin-Protein Ligases; D000097584:DNA Methyltransferase 3B
D022762:CCAAT-Enhancer-Binding Proteins; D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A; D008780:Methyltransferases; D009687:Nuclear Proteins; D044767:Ubiquitin-Protein Ligases; D000097584:DNA Methyltransferase 3B; C000717967:DNMT3A protein, human; C000715535:Dnmt3a protein, mouse; C406364:UHRF1 protein, human; C117054:Uhrf1 protein, mouse