Dnmt3b recruitment through E2F6 transcriptional repressor mediates germ-line gene silencing in murine somatic tissues.
Methylation of cytosine residues within the CpG dinucleotide in mammalian cells is an important mediator of gene expression, genome stability, X-chromosome inactivation, genomic imprinting, chromatin structure, and embryonic development. The majority of CpG sites in mammalian cells is methylated in a nonrandom fashion, raising the question of how DNA methylation is distributed along the genome. Here, we focused on the functions of DNA methyltransferase-3b (Dnmt3b), of which deregulated activity is linked to several human pathologies. We generated Dnmt3b hypomorphic mutant mice with reduced catalytic activity, which first revealed a deregulation of Hox genes expression, consistent with the observed homeotic transformations of the posterior axis. In addition, analysis of deregulated expression programs in Dnmt3b mutant embryos, using DNA microarrays, highlighted illegitimate activation of several germ-line genes in somatic tissues that appeared to be linked directly to their hypomethylation in mutant embryos. We provide evidence that these genes are direct targets of Dnmt3b. Moreover, the recruitment of Dnmt3b to their proximal promoter is dependant on the binding of the E2F6 transcriptional repressor, which emerges as a common hallmark in the promoters of genes found to be up-regulated as a consequence of impaired Dnmt3b activity. Therefore, our results unraveled a coordinated regulation of genes involved in meiosis, through E2F6-dependant methylation and transcriptional silencing in somatic tissues.
Velasco
Guillaume
G
Centre National de la Recherche Scientifique, University Paris Diderot, 75013 Paris, France.
Hubé
Florent
F
Rollin
Jérôme
J
Neuillet
Damien
D
Philippe
Cathy
C
Bouzinba-Segard
Haniaa
H
Galvani
Angélique
A
Viegas-Péquignot
Evani
E
Francastel
Claire
C
D000818:Animals; D015153:Blotting, Western; D047369:Chromatin Immunoprecipitation; D018899:CpG Islands / Q000235:genetics; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism*; D019175:DNA Methylation; D050701:E2F6 Transcription Factor / Q000378:metabolism*; D020868:Gene Silencing / Q000502:physiology*; D018398:Homeodomain Proteins / Q000235:genetics; D008540:Meiosis / Q000235:genetics*; D051379:Mice; D008817:Mice, Mutant Strains; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic / Q000235:genetics; D012097:Repressor Proteins / Q000378:metabolism*; D000097584:DNA Methyltransferase 3B
D004248:DNA (Cytosine-5-)-Methyltransferases; D050701:E2F6 Transcription Factor; D018398:Homeodomain Proteins; D012097:Repressor Proteins; D000097584:DNA Methyltransferase 3B; C111236:E2f6 protein, mouse