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[A1CR]

Maybe, "lifespan extension by CR is independent of sirtuins
and that
nicotinamide has sirtuin-independent effects on lifespan
extension by CR".

Tsuchiya M, Dang N, Kerr EO, Hu D, Steffen KK, Oakes JA,
Kennedy BK,
Kaeberlein M.
Sirtuin-independent effects of nicotinamide on lifespan
extension from
calorie restriction in yeast.
Aging Cell. 2006 Dec;5(6):505-14.
PMID: 17129213

Two models have been proposed for how calorie restriction
(CR) enhances
replicative longevity in yeast: (i) suppression of rDNA
recombination
through activation of the sirtuin protein deacetylase Sir2
or (ii) decreased
activity of the nutrient-responsive kinases Sch9 and TOR. We
report here
that CR increases lifespan independently of all Sir2-family
proteins in
yeast. Furthermore, we demonstrate that nicotinamide, an
inhibitor of
Sir2-mediated deacetylation, interferes with lifespan
extension from CR, but
does so independent of Sir2, Hst1, Hst2, and Hst4. We also
find that 5 mm
nicotinamide, a concentration sufficient to inhibit other
sirtuins, does not
phenocopy deletion of HST3. Thus, we propose that lifespan
extension by CR
is independent of sirtuins and that nicotinamide has
sirtuin-independent
effects on lifespan extension by CR.