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Quantifying Yeast Chronological Life Span by Outgrowth of Aged Cells
12:24

Quantifying Yeast Chronological Life Span by Outgrowth of Aged Cells

Published on: May 6, 2009

Yeast life-span extension by calorie restriction is independent of NAD fluctuation

Rozalyn M Anderson1, Magda Latorre-Esteves1, Ana Rute Neves2

  • 1Department of Pathology, Harvard Medical School, 200 Longwood Avenue, Boston MA 02115, USA.

Science (New York, N.Y.)
|November 8, 2003
PubMed

Insights

Calorie restriction (CR) slows aging by reducing nuclear NAD+ levels. However, the key enzyme Sir2

Area of Science:

  • Aging research
  • Molecular biology
  • Genetics

Background:

  • Calorie restriction (CR) is a dietary intervention known to extend lifespan across various species.
  • The protein Sir2 (Sirtuin 2) in yeast (Saccharomyces cerevisiae) is crucial for mediating the aging-retarding effects of CR.
  • Sir2 is a conserved NAD+-dependent deacetylase, suggesting a role for NAD+ metabolism in aging.

Purpose of the Study:

  • To investigate the effect of CR on nuclear NAD+ levels in vivo.
  • To determine if the NAD+:NADH ratio influences the activity of Sir2 and its human homologue, SIRT1.
  • To identify alternative mechanisms by which CR regulates Sir2 activity.

Main Methods:

  • Measurement of nuclear NAD+ levels in yeast under CR conditions.
  • In vitro assays to assess the activity of Sir2 and SIRT1.
  • Manipulation of NAD+:NADH ratios to observe effects on enzyme activity.

Main Results:

  • Calorie restriction was found to decrease nuclear NAD+ levels in vivo.
  • The enzymatic activity of both yeast Sir2 and human SIRT1 was not significantly altered by physiological changes in the NAD+:NADH ratio.
  • These findings suggest that the NAD+ level reduction is not the primary driver for Sir2/SIRT1 activity modulation by CR.

Conclusions:

  • CR-mediated lifespan extension in yeast does not appear to be regulated by changes in the NAD+:NADH ratio affecting Sir2/SIRT1 activity.
  • Alternative regulatory pathways for Sir2/SIRT1 by CR are likely involved in the aging process.
  • Further research is needed to elucidate these alternate mechanisms of Sir2 regulation by CR.

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