Restricted mobility of Dnmt1 in preimplantation embryos: implications for epigenetic reprogramming.
BACKGROUND
Mouse preimplantation development is characterized by both active and passive genomic demethylation. A short isoform of the prevalent maintenance DNA methyltransferase (Dnmt1S) is found in the cytoplasm of preimplantation embryos and transiently enters the nucleus only at the 8-cell stage.


RESULTS
Using GFP fusions we show that both the long and short isoforms of Dnmt1 localize to the nucleus of somatic cells and the cytoplasm of preimplantation embryos and that these subcellular localization properties are independent of phosphorylation. Importantly, photobleaching techniques and salt extraction revealed that Dnmt1S has a very restricted mobility in the cytoplasm, while it is highly mobile in the nucleus of preimplantation embryos.


CONCLUSIONS
The restricted mobility of Dnmt1S limits its access to DNA and likely contributes to passive demethylation and epigenetic reprogramming during preimplantation development.
Grohmann
Maik
M
Department of Biology II, Ludwig Maximilians University Munich, Grosshadernerstr. 2, 82152 Planegg-Martinsried, Germany. grohmann@molgen.mpg.de
Spada
Fabio
F
Schermelleh
Lothar
L
Alenina
Natalia
N
Bader
Michael
M
Cardoso
M Cristina
MC
Leonhardt
Heinrich
H
D000818:Animals; D001755:Blastocyst / Q000201:enzymology*; D002467:Cell Nucleus; D003593:Cytoplasm; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics* / Q000378:metabolism*; D019175:DNA Methylation; D004622:Embryo, Mammalian; D047108:Embryonic Development / Q000235:genetics; D044127:Epigenesis, Genetic; D049452:Green Fluorescent Proteins; D007527:Isoenzymes; D051379:Mice; D021381:Protein Transport; D011993:Recombinant Fusion Proteins
D007527:Isoenzymes; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619381:Dnmt1 protein, mouse