SCIENCE 25. 1. 2013

SCIENCE: Germline DNA Demethylation Dynamics and Imprint Erasure Through 5-Hydroxymethylcytosine

"Mouse primordial germ cells (PGCs) undergo sequential epigenetic changes and genome-wide DNA demethylation to reset the epigenome for totipotency. Here, we demonstrate that erasure of CpG methylation (5mC) in PGCs occurs via conversion to 5-hydroxymethylcytosine (5hmC), driven by high levels of TET1 and TET2. Global conversion to 5hmC initiates asynchronously among PGCs at embryonic day (E) 9.5 to E10.5 and accounts for the unique process of imprint erasure. Mechanistically, 5hmC enrichment is followed by its protracted decline thereafter at a rate consistent with replication-coupled dilution. The conversion to 5hmC is an important component of parallel redundant systems that drive comprehensive reprogramming in PGCs. Nonetheless, we identify rare regulatory elements that escape systematic DNA demethylation in PGCs, providing a potential mechanistic basis for transgenerational epigenetic inheritance."

http://www.sciencemag.org/content/339/6118/448.abstract

NATURE: Cancer: The to and fro of tumour spread

"Two studies shed light on the role of cellular transitions between the epithelial and mesenchymal states during cancer metastasis, and provide food for thought as to which cellular processes should be targeted in cancer treatment."

http://www.nature.com/nature/journal/v493/n7433/full/493487a.html

NATURE: GENOMICS: Gene linked to Alzheimer's

"Two studies have identified a rare genetic mutation that boosts the risk of Alzheimer's disease. Kári Stefánsson of deCODE Genetics in Reykjavik and his group analysed the genomes of 2,261 Icelanders and uncovered a mutation in the TREM2 gene that increased the risk of Alzheimer's disease roughly threefold. (...)"

http://www.nature.com/nature/journal/v493/n7433/full/493454d.html

NATURE: Editorial: Genetic privacy

"The ability to identify an individual from their anonymous genome sequence, using a clever algorithm and data from public databases, threatens the principle of subject confidentiality."

http://www.nature.com/news/genetic-privacy-1.12238