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

[The Avantguardian]

--- Damien Broderick <thespike at satx.rr.com> wrote:

> Robert J. Bradbury posts on another list:
> If this turns out to be real then it means the whole
> ball of
> wax may be up for grabs.  I.e. once we lay our hands
> on the molecules
> that determine the state of the nucleus then it
> could be possible
> to revert the DNA of any nucleus to a stem cell
> state.  (The
> eggs or stem cell lines will probably become
> non-essential
> components of the process.)

This approach will run into a problem. From molecular
studies of mouse development, we know that part of the
genetic program of cell differentiation as the mouse
embryo develops involves methylation of various genes
to silence them as the cell starts to specialize into
a particular tissue. In other words, the cells
"permanently" shut off a large number of genes after
they have done their job in development. 

The whole point of using an oocyte in the cloning
process is that the egg contains enzymes that
demethylate all of the genes during the zygote stage,
effectively "rebooting" the genetic program and making
all genes available for transcription once again. The
egg cell is like the reset button of the genetic
operating system. If you try to do a nuclear transfer
into an ES cell, the DNA would not be able to fully
reset and this theoretically would limit these cells
to some form of pluripotency instead of totipotency.

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



The Avantguardian 
is 
Stuart LaForge
alt email: stuart"AT"ucla.edu

"The surest sign of intelligent life in the universe is that they haven't attempted to contact us." 
-Bill Watterson


		
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