[tt] [x-risk] Life-extending protein can also have damaging effects on brain cells

[Eugen Leitl]

----- Forwarded message from arsen zahray <menkaur at gmail.com> -----

From: arsen zahray <menkaur at gmail.com>
Date: Wed, 2 Jul 2008 05:07:45 +0300
To: existential at transhumanism.org
Subject: [x-risk] Life-extending protein can also have damaging effects on
	brain cells
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Reply-To: For discussion of existential risks <existential at transhumanism.org>


   [1]http://www.physorg.com/news134135331.html


   Proteins widely believed to protect against aging can actually cause
   oxidative damage in mammalian brain cells, according to a new report
   in the July Cell Metabolism, a publication of Cell Press. The findings
   suggest that the proteins can have both proaging and protective
   functions, depending on the circumstances, the researchers said.


   " Sirtuins are very important proteins," said Valter Longo of the
   University of Southern California, Los Angeles. "Overexpression can
   protect in some cases, and in other cases, it may do the opposite. It
   has to do with the fact that they do so many things."
   Sirtuins, or Sir2 family proteins, are found in organisms from
   bacteria to humans. Sir2 controls aging and life span in yeast, the
   worm C. elegans, and Drosophila fruit flies, earlier studies have
   shown.
   Studies have also implicated Sir2 in the life-extending effects of a
   calorie restricted diet in some, though not all, organisms. Notably,
   Longo's lab showed that lack of Sir2 in yeast further extended the
   life span of calorie-restricted cells.
   SirT1, the mammalian version of yeast Sir2, controls numerous
   physiological processes including glucose metabolism, DNA repair, and
   cell death, the researchers added. In mammalian cells, SirT1 also
   controls several stress-response factors.

   Now, the researchers show that cultured rat neurons treated with a
   SirT1 inhibitor more often survived treatment with oxidative
   stress-inducing chemicals. They further show evidence to explain the
   mechanism responsible for that effect.
   They also found lower oxidative stress levels in the brains of mice
   without SirT1. However, those SirT1 knockout mice didn't live as long
   as normal mice do on either a normal or a calorie-restricted diet.
   " [Such drugs] could have beneficial effects for certain diseases, but
   again, these proteins do a lot of things," he said. "I would say the
   idea that there is a conserved action of sirtuins to cause major life
   span extension--the foundations for that are weak or very weak. Until
   we have more data to show that chronic treatment to increase SirT1
   activity does not do damage, I don't think it's a good idea."

References

   1. http://www.physorg.com/news134135331.html

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