Premature Ageing

Jean-Pierre Issa jpissa at welchlink.welch.jhu.edu
Mon Apr 1 20:09:03 EST 1996


GuyD at world.net (Guy Dunphy) wrote:


>>> Isn't it amazing the number of researchers who are looking into telomeres,
>>> 'just for the cancer connection'!
>>> What a bunch of funding whimps. Go on, admit it you guys, WE ALL WANT TO BE
>>> IMMORTAL.

(Lots of stuff deleted)
>
>But I just have a gut feeling that telomere loss is the major cause of the
>'cellular death' clock.  (Hope its not just wishful thinking.)
>
>


There are many more good labs studying the telomere/aging connection
than you imply. Unfortunately, there are many holes in the
(fascinating) speculation that telomere loss 'causes' aging. Some that
come to mind:
1- Many normal cells (specially stem cells) express telomerase and
thus can repair/replace any significant telomere loss.
2- Cells from elderly individuals have not yet reached a 'critical'
telomere shortening (which happens if you culture these cells to
senescence.
3- Dr. Blackburn (one of the telomere pioneers) has shown that in
Tetrahymena (I think, but I may be wrong), telomeres shorten until
middle-age, THEN they start elongating again! At the end of these
organisms' life span, their telomeres are nearly the same length as
when they are born. (PNAS, 1994).

Thus, the telomere loss - aging connection remains somewhat
speculative. It is possible that even a small degree of telomere
shortening causes significant changes in gene expression elsewhere in
the genome, thus linking it to aging, but I do not think this has been
firmly demonstrated yet.

But I assure you, much research into telomere length and aging is
going on !

Regards,
Jean-Pierre Issa, MD
Johns Hopkins Oncology Center




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