Mail*Link( SMTP FWD>RE>Telomerase & Aging
Dear Atsushi,
It would be helpful to know how you quantitated telomerase activity, was it by
serial dilution, and what tumor cell line did you compare it to? Did you do a
time course on the effect of PMA, what other cytokines were added (IL-2)?
There is not yet a lot of data on telomeres and telomerase in cultured
lymphocytes but the history of research in the field suggests that they lose
telomeric DNA with age and have a finite replicative lifespan in vitro and are
clearly losing telomeres in vivo.
mwest at geron.com
--------------------------------------
Date: 4/14/96 3:04 PM
From: Atsushi Konishi
In article <Pine.OSF.3.91.960411033730.17300C-100000 at gaston.tenet.edu>,
dashley at TENET.EDU (Don Ashley) wrote:
>> Comment: The striking thing about telomerase expression which is thought
to
>> make cells immortal, is that it is NOT expressed by many cell types. It is
>> clearly abundant in the reproductive cells which obviously allows them to
make
>> the species immortal, and abnormally in malignant cells likewise conferring
>> replicative immortality to them, however, it is conspicuously absent in
most
>> somatic cells and tissues. It appears to be true that there is a low
(<100X
>> less activity) of telomerase in candidate hematapoietic stem cells, but the
>> biology there is not clear and all the evidence suggests that telomeres are
>> being lost with age in vivo in these cells and when the candidate cells are
>> passaged in vitro as well. So clearly the telomerase that is there is not
>> repairing telomere loss. The only normal cells that are known to have
stable
>> telomeres are the reproductive cells. (Keratinocyte stem cells may also
have
>> low levels, but again, they are not maintaining telomere length)
Some recent paper about PBLs culturing with PHA says that telomerase
activity
increases more than 100 times in these cells. I re-examined this with My
PBLs
and their activity really increased as high as cancer cells. Are these
results
artifacts relating with the TRAP method? Or the data from telomerase assay
in in vitro
have nothing to do with the activity in in vivo with these cells?
Does anyone over there have suggestions about this?
Thanks.
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To: ageing at net.bio.net
From: akonishi at soda3.bekkoame.or.jp (Atsushi Konishi)
Subject: Re: Telomerase & Aging
Date: Sat, 13 Apr 1996 20:09:28 +0900
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