X-Message-Number: 25369
Date: Tue, 21 Dec 2004 09:43:13 EST
Subject: telomeres limit both cancer and extreme lifespan

>telomeres appear to play no role in either human skin
aging, or bone marrow aging.]


>Telomerase activity was similar in aged and
young epidermis. 

Yes, but telomerase is expressed only in stem cells, and even there it's not 
enough to prevent shortening. I just tried to force some BJ fibroblasts to 

express telomerase in a dish (as a practical joke), and they wouldn't do it even
with fetal cow hormones and partial synchronizing in S phase. My TRFs on white 
blood cells from different-age donors show a very large shortening over time 
(though the longest old telomeres are longer than the shortest young-cell 
telomeres; there's a lot of individual variation). 

Seriously, factors other than telomere shortening are more important before 
advanced age. Being able to turn off telomerase is more important in the short 
term (to kill cancers), but eventually you'll need them there telomeres. And I 
don't say that just because I work in a telomerase lab...

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