[extropy-chat] [fwd] Another path to stem cells?

[Damien Broderick]

>[Robert J. Bradbury responds:]

 > This was a quick and dirty explanation. See the
 > following link for a more thorough review:
 >
 > http://jcs.biologists.org/cgi/content/abstract/113/1/11

This is a rather old article (2000).

More up to date is:
DNA demethylation is necessary for the epigenetic reprogramming of
somatic cell nuclei.  Simonsson S, Gurdon J.
Nat Cell Biol 2004 Oct;6(10):984-90
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15448701

[Damien:]
I'd assumed that the stembrid method would do the
demethylation, among other necessary things.

[Robert:]
Yes, obviously a "reset" has to occur.  The question is how
that may be accomplished?  Obviously if the oocytes or eggs
have the proper demethylase(s) turned on then it should not
be too difficiult to either turn them on in non-eggs/oocytes
or if that proves difficult to add them (heck if one can
inject a nucleus then injecting a bunch of purified proteins
in addition can't be *that* difficult).   And it isn't as if
we don't have the whole human genome and don't know *what*
the demethylase enzymes/complexes *are* (start with MBD1/2/3/4).
They also appear to be involved in histone deacetylation
[though I do not claim to be an expert in this area].

I would imagine that a "clever" way to work around the whole
"an embryo is life" problem is to use the reset proteins from
other species.  I would expect these have to be highly conserved
during evolution.  Mess with this function and you probably
break eukaryotic reproduction.

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Damien Broderick