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Cellular senescence- is it aging? was Defining...

Steve Chambers steve at chambers.ak.planet.co.nz
Sat Apr 1 22:55:43 EST 1995


In <grovesa-0104951428020001 at 131.215.5.171> grovesa at starbase1.caltech.edu (Andrew K. Groves) writes:

>I think there is a confusion here between biological ageing and
>pathological conditions which lower life span - between cellular and
>organismal aging, if you will. If you place a population of human
>fibroblasts in culture, they will divide for a certain number of times and
>stop. They will not die, they'll just sit there. If you're skilful, you
>can maintain such senescent cultures for months and even years. But the
>point is that those cells have all stopped dividing after a seemingly
>pre-programmed period of time. How could random wear and tear account for
>such an impressive synchrony of withdrawal from the cell cycle?

>I'm not suggesting that senscence has a single cause - indeed, the work of
>Olivia Pereira-Smith would suggest that there are several mechanisms on
>the basis of genetic complementation in somatic cell fusion experiments.
>Your "100+" mechanisms of wera and tear may well explain why people die,
>or get cancer or whatever, but they may not be able to account for the
>reproducible obseravtion of cellular senescence.

Andy

There's a tendency for those of us who've spent most of our studies
in cellular and molecular biology to think that the term senescence 
(and by implication aging) only applies to cells.  It doesn't - and
for most of the community the terms apply principally to whole
organisms.

The processes that dictate the "lifespan" of a cell or clone are but 
a small subset of those that should be examined when studying aging.

Genetic control is plainly a major factor in cellular senescence but 
cellular senescence probably doesn't "explain why people die."  There's 
a hackneyed quote in gerontology: "Nobody dies of old skin."

You have to ask yourself a question: If current definitions of aging
(including one that relies upon cellular senescence) don't "explain why 
people die" then how useful are they?

Steve

-- 
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(I_lurk,_therefore_I_am!_\ ,,,                    Steve Chambers
                          (o o)   steve at chambers.ak.planet.co.nz
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(c) Steve Chambers                     1995. All rights reserved 
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