> ... .
> I want to suggest that DNA methylation holds some answers to your
> questions.
> Although I don't know much about it, as far as I know, DNA methylation
> patterns change as a cell differentiates, or ages.
> Perhaps DNA methylation appeares to be involved in transcription
> regulation. I remember the journal Cell has several good reviews on it.
> I hope that this discussion goes on.
> Is there anyboy to comment it? I am really excited by this great post.
>> Best regards
> Hang-Jun Jang
Richard Cutler has proposed what he calls the "disdifferentiation
hypothesis," basically, that a big cause of the disfunctions of aging
may be that differentiated cells tend to loose their specificity over
time so that, for example, neurons tend to make more muscle proteins,
livers make more skin proteins, etc. That they do so is supposedly an
experimental fact; what is in question is whether that is indeed a deep
cause of the manifestations of aging, or whether it is more an effect
than a cause. (Sorry, I can't give references right now.) Presumably,
too, one main way that the differentiation of cells is maintained is by
methylation of DNA. (Though I think that methylation is supposedly used
to do some imprinting across generations, i.e., for some genes it matter
whether you got the gene from your mother or father, and that the
mechanism for this sex imprinting is methylation of DNA. So perhaps just
putting the nucleus of an adult cell into an egg is not enough to remove
all methylation.)
.. jj
