Chemical ‘clock’ tracks ageing more precisely than ever before

DNA methylation suggests cancerous tissue ages faster than healthy tissue.

Chemical ‘clock’ tracks ageing more precisely than ever before
DNA methylation could shed light on why some tissues are prone to cancer.
Amanda Mascarelli
Nature. 21 October 2013
http://www.nature.com/news/chemical-clock-tracks-ageing-more-precisely-than-ever-before-1.13981

In a paper published today in Genome Biology, Horvath reveals how methylation levels change in human tissues from before birth to the age of 101, and shows that it is a near-perfect predictor of age for non-cancerous tissues.
The study “represents the most convincing demonstration so far” of age-associated changes in DNA methylation that are consistent across most tissue types, says Andrew Teschendorff, a computational biologist at University College London.

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DNA methylation age of human tissues and cell types
Genome Biology 2013, 14(10):R115
Steve Horvath
http://genomebiology.com/2013/14/10/R115

Conclusions: I propose that DNA methylation age measures the cumulative effect of an epigenetic maintenance system. This novel epigenetic clock can be used to address a host of questions in developmental biology, cancer and aging research.

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ScienceClub: Oct. 29, 2013

The agouti mouse model

The viable yellow agouti (Avy) mouse model

The agouti mouse model: an epigenetic biosensor for nutritional and environmental alterations on the fetal epigenome
Nutr Rev. 2008 August; 66(Suppl 1): S7–11.
Dana C Dolinoy
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2822875

Epigenetic mechanisms include chromatin folding and attachment to the nuclear matrix, packaging of DNA around nucleosomes, covalent modifications of histone tails (e.g. acetylation, methylation, phosphorylation), and DNA methylation.
The influence of regulatory small RNAs and micro RNAs on gene transcription is also increasingly recognized as a key mechanism of epigenetic gene regulation.

The viable yellow agouti (Avy) mouse model, in which coat color variation is correlated to epigenetic marks established early in development, has been used to investigate the impacts of nutritional and environmental influences on the fetal epigenome. The wild-type murine Agouti gene encodes a paracrine signaling molecule that produces either black eumelanin (a) or yellow phaeomelanin (A).