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J Biol Chem. 2015 May 15;290(20):12753-64. doi: 10.1074/jbc.M115.644534. Epub 2015 Mar 30.

Reduced Ssy1-Ptr3-Ssy5 (SPS) signaling extends replicative life span by enhancing NAD+ homeostasis in Saccharomyces cerevisiae.

Author information

1
From the Department of Microbiology and Molecular Genetics, College of Biological Sciences, University of California, Davis, California 95616.
2
From the Department of Microbiology and Molecular Genetics, College of Biological Sciences, University of California, Davis, California 95616 slin@ucdavis.edu.

Abstract

Attenuated nutrient signaling extends the life span in yeast and higher eukaryotes; however, the mechanisms are not completely understood. Here we identify the Ssy1-Ptr3-Ssy5 (SPS) amino acid sensing pathway as a novel longevity factor. A null mutation of SSY5 (ssy5Δ) increases replicative life span (RLS) by ∼50%. Our results demonstrate that several NAD(+) homeostasis factors play key roles in this life span extension. First, expression of the putative malate-pyruvate NADH shuttle increases in ssy5Δ cells, and deleting components of this shuttle, MAE1 and OAC1, largely abolishes RLS extension. Next, we show that Stp1, a transcription factor of the SPS pathway, directly binds to the promoter of MAE1 and OAC1 to regulate their expression. Additionally, deletion of SSY5 increases nicotinamide riboside (NR) levels and phosphate-responsive (PHO) signaling activity, suggesting that ssy5Δ increases NR salvaging. This increase contributes to NAD(+) homeostasis, partially ameliorating the NAD(+) deficiency and rescuing the short life span of the npt1Δ mutant. Moreover, we observed that vacuolar phosphatase, Pho8, is partially required for ssy5Δ-mediated NR increase and RLS extension. Together, our studies present evidence that supports SPS signaling is a novel NAD(+) homeostasis factor and ssy5Δ-mediated life span extension is likely due to concomitantly increased mitochondrial and vacuolar function. Our findings may contribute to understanding the molecular basis of NAD(+) metabolism, cellular life span, and diseases associated with NAD(+) deficiency and aging.

KEYWORDS:

NAD biosynthesis; cell metabolism; metabolic regulation; nicotinamide riboside salvage; yeast genetics; yeast metabolism

PMID:
25825491
PMCID:
PMC4432292
DOI:
10.1074/jbc.M115.644534
[Indexed for MEDLINE]
Free PMC Article

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