Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2011 Sep 21;477(7365):482-5.
doi: 10.1038/nature10296.

Absence of effects of Sir2 overexpression on lifespan in C. elegans and Drosophila

Affiliations

Absence of effects of Sir2 overexpression on lifespan in C. elegans and Drosophila

Camilla Burnett et al. Nature. .

Abstract

Overexpression of sirtuins (NAD(+)-dependent protein deacetylases) has been reported to increase lifespan in budding yeast (Saccharomyces cerevisiae), Caenorhabditis elegans and Drosophila melanogaster. Studies of the effects of genes on ageing are vulnerable to confounding effects of genetic background. Here we re-examined the reported effects of sirtuin overexpression on ageing and found that standardization of genetic background and the use of appropriate controls abolished the apparent effects in both C. elegans and Drosophila. In C. elegans, outcrossing of a line with high-level sir-2.1 overexpression abrogated the longevity increase, but did not abrogate sir-2.1 overexpression. Instead, longevity co-segregated with a second-site mutation affecting sensory neurons. Outcrossing of a line with low-copy-number sir-2.1 overexpression also abrogated longevity. A Drosophila strain with ubiquitous overexpression of dSir2 using the UAS-GAL4 system was long-lived relative to wild-type controls, as previously reported, but was not long-lived relative to the appropriate transgenic controls, and nor was a new line with stronger overexpression of dSir2. These findings underscore the importance of controlling for genetic background and for the mutagenic effects of transgene insertions in studies of genetic effects on lifespan. The life-extending effect of dietary restriction on ageing in Drosophila has also been reported to be dSir2 dependent. We found that dietary restriction increased fly lifespan independently of dSir2. Our findings do not rule out a role for sirtuins in determination of metazoan lifespan, but they do cast doubt on the robustness of the previously reported effects of sirtuins on lifespan in C. elegans and Drosophila.

PubMed Disclaimer

Figures

Figure 1
Figure 1. C. elegans: Longevity of LG100 and NL3909 is not attributable to sir-2.1 over-expression
a, b. Outcrossing of LG100 removes life extension without affecting SIR-2.1 protein levels. Data in b derived from Western blots (mean of three trials each using an independent protein preparation). A representative Western blot is shown in Fig S1a. qRT-PCR showed that sir-2.1 mRNA is also elevated in both strains (data not shown). c, LG100-derived Dyf, non-Rol segregant lines are long-lived while non-Dyf, Rol lines are not. d. Non-Dyf Rol segregant lines have elevated SIR-2.1 levels, while Dyf, non-Rol lines do not. e, f. sir-2.1 RNAi does not suppress LG100 longevity, but reduces SIR-2 protein levels. g, h. Outcrossing of NL3909 removes life extension without affecting SIR-2.1 protein levels. See Tables S1, S3, S4 and S5 for lifespan statistics for a, c, e and g, respectively. Error bars, S.E.M.. *0.01< P < 0.05; ** 0.001 < P < 0.01; ***P < 0.001, n.s., not significant; Student’s t test (two tailed). One remaining possibility is that the outcrossed sir-2.1 strains both contain second site mutations that suppress longevity effects. However, daf-2 RNAi strongly induced longevity in both (data not shown), arguing against the presence of a general suppressor of longevity in each case.
Figure 2
Figure 2. Drosophila: Absence of effects of dSir2 on lifespan
All lines were outcrossed into wDah (+/+) a, Lifespan in flies over-expressing dSir2EP2300 driven via tubulin-GAL4 (tub-GAL4) is longer than wild type, but not than the tubulin-GAL4 /+ genetic control. Median lifespans: +/+ = 39 days, dSir2EP2300/tubulin-GAL4 = 59 days, dSir2EP2300/+ = 53 days, tubulin-GAL4 /+ = 60 days. dSir2EP2300/tubulin-GAL4 vs. dSir2EP2300/+, P = 0.0006; dSir2EP2300/tubulin-GAL4 vs. tubulin-GAL4 /+, P = 0.9295; dSir2EP2300/tubulin-GAL4 vs. +/+, P <0.0001 . b, Lifespan in flies over-expressing dSir2-Myc9 is longer than in wild type, but not than in the tubulin-GAL4 control. Median lifespans: +/+ = 39 days, dSir2-Myc9/tubulin-GAL4 = 67, dSir2-Myc9/+ = 41 days, tubulin-GAL4/+ = 60 days. dSir2-Myc9/tubulin-GAL4 vs. dSir2-Myc9/+, P = 0.0001; dSir2-Myc9/tubulin-GAL4 vs. tubulin-GAL4/+, P = 0.1354; dSir2-Myc9/tubulin-GAL4 vs. +/+, P <0.0001. Compared using log rank test, n=200. c, Effect of dietary restriction on Drosophila lifespan is not dSir2 dependent. Flies were assayed over five concentrations of SYA media and data are presented as the median lifespan on each food concentration. All lines were outcrossed into Canton S (+/+). P values confirm that all flies respond normally to DR when median lifespans are compared for DR vs. fully-fed (FF) conditions.

Comment in

References

Additional references

    1. Brenner S. The genetics of Caenorhabditis elegans. Genetics. 1974;77:71–94. - PMC - PubMed
    1. Sulston J, Hodgkin J. In: The nematode Caenorhabditis elegans. Wood WB, editor. Cold Spring Harbor; 1988. pp. 587–606.
    1. Kamath R, et al. Systematic functional analysis of the Caenorhabditis elegans genome using RNAi. Nature. 2003;421:231–237. - PubMed
    1. Greiss S, Hall J, Ahmed S, Gartner A. C. elegans SIR-2.1 translocation is linked to a proapoptotic pathway parallel to cep-1/p53 during DNA damage-induced apoptosis. Genes Dev. 2008;22:2831–2842. - PMC - PubMed
    1. Newman BL, Lundblad JR, Chen Y, Smolik SM. A Drosophila homologue of Sir2 modifies position-effect variegation but does not affect life span. Genetics. 2002;162:1675–1685. - PMC - PubMed

References

    1. Tissenbaum HA, Guarente L. Increased dosage of a sir-2 gene extends life span in Caenorhabditis elegans. Nature. 2001;410:227–230. - PubMed
    1. Viswanathan M, Kim SK, Berdichevsky A, Guarente L. A role for SIR-2.1 regulation of ER stress response genes in determining C. elegans life span. Dev Cell. 2005;9:605–615. - PubMed
    1. Rogina B, Helfand S. Sir2 mediates longevity in the fly through a pathway related to calorie restriction. Proc Natl Acad Sci USA. 2004;101:15998–16003. - PMC - PubMed
    1. Partridge L, Gems D. Benchmarks for ageing studies. Nature. 2007;450:165–167. - PubMed
    1. Kaeberlein M, McVey M, Guarente L. The SIR2/3/4 complex and SIR2 alone promote longevity in Saccharomyces cerevisiae by two different mechanisms. Genes Dev. 1999;13:2570–2580. - PMC - PubMed

Publication types

MeSH terms