'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
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