After living the life of a toxin-and-bat head imbibing rock and roller, shouldn’t Ozzy Osbourne be near death? No one knows, but he is getting his genome mapped, in an effort to find out why he’s still alive.
Not to be ungrateful to la familia Osbourne, who comforts us with their dysfunction, but we would rather Le Père Osbourne got his epigenome mapped because it turns out brain DNA is chock full of methyl groups.
Ghosh et al. (bel0w) demonstrate that, as compared to other peripheral tissues, neural tissue, and particularly brain gray and white matter tissue, is chock full of methylation, one of the text book ways to turn on and off genes in particular places at particular times. This makes perfect sense to us: animals need to regulate different parts of their bodies at different times in response to the environment. For instance, epigenetics and immune function go hand in hand (e.g., here, immune genes are un-methylated with PTSD, causing an immune over-response). What better way to kick back and respond to the environment that popping the top on the immune gene promoters and downing some of them bad boy antibody transcripts?
Our guess is that it’s probably not the amount of methylation, but the degree to which methylation/de-methylation/re-methylation runs smoothly. There’s epigenetic drift, as one ages or lives the life of a rock and roller. Ozzy’s epigenome would be pretty interesting, in fact, in a longititudinal study if there’s any Ozzy DNA laying around from years ago.
The paper: Ghosh S, Yates AJ, Frühwald MC, Miecznikowski JC, Plass C, Smiraglia DJ. Tissue specific DNA methylation of CpG islands in normal human adult somatic tissues distinguishes neural from non-neural tissues. Epigenetics. 2010 Aug 4;5(6). (abstract after the jump)
In the current study, we used Restriction Landmark Genomic Scanning to study tissue specific methylation patterns in a set of twelve human tissues collected from multiple individuals. We identified 34 differentially methylated CpG islands among these tissues, many of which showed consistent patterns in multiple individuals. Of particular interest were striking differences in CpG island methylation, not only among brain regions, but also between white and grey matter of the same region. . . . Cluster analysis of the RLGS data indicated that several tissues clustered together, but the strongest clustering was in brain. Tissues from different brain regions clustered together, and, as a group, brain tissues were distinct from either mesoderm or endoderm derived tissues which demonstrated limited clustering. These data demonstrate consistent tissue specific methylation for certain CpG islands, with clear differences between white and grey matter of the brain. Furthermore, there was an overall pattern of tissue specifically methylated CpG islands that distinguished neural tissues from non-neural.