'Longevity' gene, diet linked
SIRT1 may play role in why calorie restriction leads to longer life in rats
By David Secko

Experiments on yeast, worms, and mammals have all revealed that cutting
calories extends lifespan, but how is this occurs is largely unknown. Now,
two independent studies, one reported in the June 18 Science, from David
Sinclair's laboratory at Harvard Medical School, and the other reported in
the June 3 Nature, from Leonard Guarente's laboratory at Massachusetts
Institute of Technology, have uncovered molecular mechanisms linking aging,
diet, and a gene called SIRT1.

"People have been studying calorie restriction for 70 years, yet the
mechanism is not known," said Sinclair, adding that this new work has
finally started to suggest a primary mechanism.

In the past, calorie restriction was theorized to be a passive mechanism,
whereby fewer calories reduced metabolism and the oxidative stresses that
come with it. But the discovery that the protein Sir2-of which SIRT1 is the
mammalian orthologue-extends lifespan in yeast and worms, suggested a more
regulated mechanism involving Sir2. It was not known if this extended to
mammals and SIRT1, and both teams were trying to tackle this question.

In the Science study, Sinclair, lead author Haim Cohen, and their colleagues
investigated how SIRT1 was involved in calorie restriction in rats, keying
on the concept that aging results in cell loss over time. "Caloric
restriction and genetic manipulations that extend lifespan typically protect
cells from death," Sinclair told The Scientist.

Read the rest at The Scientist
http://www.biomedcentral.com/news/20040618/01

Posted by
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