title: Mammalian DNA methyltransferases show different subnuclear distributions.
abstract: In mammalian cells, DNA methylation patterns are precisely maintained after DNA replication with defined changes occurring during development. The major DNA methyltransferase (Dnmt1) is associated with nuclear replication sites during S-phase, which is consistent with a role in maintenance methylation. The subcellular distribution of the recently discovered de novo DNA methyltransferases, Dnmt3a and Dnmt3b, was investigated by immunofluorescence and by epitope tagging. We now show that both Dnmt3a and Dnmt3b are distributed throughout the nucleoplasm but are not associated with nuclear DNA replication sites during S-phase. These results suggest that de novo methylation by Dnmt3a and Dnmt3b occurs independently of the replication process and might involve an alternative mechanism for accessing the target DNA. The different subcellular distribution of mammalian DNA methyltransferases might thus contribute to the regulation of DNA methylation.
authors.affiliation: Max Delbrück Center for Molecular Medicine, Berlin, Germany.
authors.forename: J B
authors.initials: JB
authors.lastname: Margot
authors.forename: M C
authors.initials: MC
authors.lastname: Cardoso
authors.forename: H
authors.initials: H
authors.lastname: Leonhardt
mesh_terms: D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D019556:COS Cells; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology*; D002478:Cells, Cultured; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000737:chemistry / Q000378:metabolism; D019175:DNA Methylation; D000090205:DNA Methyltransferase 3A; D004261:DNA Replication; D000939:Epitopes / Q000378:metabolism; D006801:Humans; D008780:Methyltransferases / Q000096:biosynthesis*; D051379:Mice; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D017434:Protein Structure, Tertiary; D016196:S Phase; D014162:Transfection; D000097584:DNA Methyltransferase 3B
chemical_list: D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A; D000939:Epitopes; D008780:Methyltransferases; D000097584:DNA Methyltransferase 3B; C000717967:DNMT3A protein, human; C000715535:Dnmt3a protein, mouse