Calorie restriction extends the chronological lifespan of Saccharomyces cerevisiae independently of the Sirtuins.
Level 5 - mechanism / opinion, no new human data
Bench experiment in yeast (Saccharomyces cerevisiae)
PubMed 17711561 · doi:10.1111/j.1474-9726.2007.00326.x
What was done
Researchers examined the role of yeast sirtuins (Sir2p, Hst1p, Hst2p, Hst3p, and Hst4p) in mediating chronological lifespan (CLS) extension by calorie restriction (CR) in Saccharomyces cerevisiae. CR was induced by reducing medium glucose from 2% to 0.5%. They tested deletion mutants of individual sirtuin genes, evaluated interactions between CR and environmental stressors (low temperature, high osmolarity), assessed restriction of alternative simple sugars (galactose, fructose), and evaluated growth on nonfermentable carbon sources requiring respiration.
What was found
The abstract reports no specific survival durations, hazard ratios, or numerical percentages beyond the glucose concentrations (2% down to 0.5%). Deletions of SIR2, HST2, or HST4 did not block lifespan extension from CR. Deleting HST1 or HST3 moderately shortened baseline CLS but did not prevent CR from extending lifespan. Combining CR with low temperature or high osmolarity produced additive CLS extensions. Restricting galactose or fructose also extended CLS. Nonfermentable carbon sources extended CLS at nonrestricted levels and showed no further benefit under restriction.
Why it matters
This study demonstrates that calorie restriction promotes stationary-phase survival independently of the Sirtuin gene family in yeast, challenging the model that Sir2-family deacetylases are universal, obligate mediators of CR-induced longevity.
Limits
Findings are restricted to a single-celled fungal model (S. cerevisiae) and chronological aging, which may not directly generalize to replicative aging or mammalian physiology. The abstract provides no quantitative effect sizes, variance measures, statistical significance values, or replicate counts.
Cited by
- contradicts Deleting the SIR2 gene blocks the lifespan-extending effects of calorie restriction in yeast.