Research article

Restricted mobility of Dnmt1 in preimplantation embryos: implications for epigenetic reprogramming

Maik Grohmann^2,3 , Fabio Spada¹ , Lothar Schermelleh¹ , Natalia Alenina² , Michael Bader² , M Cristina Cardoso² and Heinrich Leonhardt^1,2

¹  Department of Biology II, Ludwig Maximilians University Munich, Grosshadernerstr. 2, 82152 Planegg-Martinsried, Germany

²  Max Delbruck Center for Molecular Medicine, Berlin, Germany

³  Max-Planck-Institute for Molecular Genetics, Berlin, Germany

author email corresponding author email

BMC Developmental Biology 2005, 5:18doi:10.1186/1471-213X-5-18

Published:	24 August 2005

Abstract

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.

Conclusion

The restricted mobility of Dnmt1S limits its access to DNA and likely contributes to passive demethylation and epigenetic reprogramming during preimplantationdevelopment.