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Enhancing S-adenosyl-methionine catabolism extends Drosophila lifespan.

Obata F, Miura M - Nat Commun (2015)

Bottom Line: Overexpression of gnmt suppresses this age-dependent SAM increase and extends longevity.Pro-longevity regimens, such as dietary restriction or reduced insulin signalling, attenuate the age-dependent SAM increase, and rely at least partially on Gnmt function to exert their lifespan-extending effect in Drosophila.Our study suggests that regulation of SAM levels by Gnmt is a key component of lifespan extension.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.

ABSTRACT
Methionine restriction extends the lifespan of various model organisms. Limiting S-adenosyl-methionine (SAM) synthesis, the first metabolic reaction of dietary methionine, extends longevity in Caenorhabditis elegans but accelerates pathology in mammals. Here, we show that, as an alternative to inhibiting SAM synthesis, enhancement of SAM catabolism by glycine N-methyltransferase (Gnmt) extends the lifespan in Drosophila. Gnmt strongly buffers systemic SAM levels by producing sarcosine in either high-methionine or low-sams conditions. During ageing, systemic SAM levels in flies are increased. Gnmt is transcriptionally induced in a dFoxO-dependent manner; however, this is insufficient to suppress SAM elevation completely in old flies. Overexpression of gnmt suppresses this age-dependent SAM increase and extends longevity. Pro-longevity regimens, such as dietary restriction or reduced insulin signalling, attenuate the age-dependent SAM increase, and rely at least partially on Gnmt function to exert their lifespan-extending effect in Drosophila. Our study suggests that regulation of SAM levels by Gnmt is a key component of lifespan extension.

No MeSH data available.


Related in: MedlinePlus

Gnmt is necessary for lifespan extension by reduced insulin signalling or dietary restriction.(a) Lifespan analysis of Gnmt-overexpressing male flies by TubGS-Gal4. Statistics, log-rank test, gnmt versus gnmt+RU, P<0.0001 (N=117 for gnmt, N=118 for gnmt+RU). gnmtS145A versus gnmtS145A+RU, P=0.7732 (N=111 for gnmtS145A, N=113 for gnmtS145A+RU). (b,d,f,j,l) Average lifespan. One-way analysis of variance (ANOVA) with Bonferroni's multiple comparison test was used for statistical analysis. (c) Lifespan analysis of gnmt-overexpressing male and female flies by TubGS-Gal4. UAS-gnmt integrated on attP2 site is used. Statistics, log-rank test, gnmt-2 male versus gnmt-2+RU male, P<0.0001 (N=116 for each). gnmt-2 female versus gnmt-2+RU female, P<0.0001 (N=116 for each). (e) Lifespan analysis of male flies overexpressing InRDN (dominant-negative form of the insulin receptor), gnmt-RNAish or both. Statistics, log-rank test, InRDN versus InRDN+RU, P<0.0001 (N=158 for InRDN, N=154 for InRDN+RU). gnmt-RNAish versus gnmt-RNAish+RU, P=0.0478 (N=80 for both). InRDN, gnmt-RNAish versus InRDN, gnmt-RNAish+RU, P<0.0001 (N=142 for InRDN, gnmt-RNAish, N=154 for InRDN, gnmt-RNAish+RU). (g) qRT–PCR analysis of InR in day-7 adult male flies treated RU486 for 5 days. Error bars represent mean±s.e.m. (N=4). Statistics, one–way ANOVA with Bonferroni's multiple comparison test. (h) Lifespan analysis of male flies overexpressing sams. Statistics, log-rank test, sams versus sams+RU, P=0.6381 (N=135 for sams, N=143 for sams+RU). Inset, average lifespan. (i) Lifespan analysis of male gnmtMi flies under dietary restriction. Statistics, log-rank test, yw 20 versus 5%, P<0.0001 (N=134 for 20%, N=132 for 5%). gnmtMi 20 versus 5%, P=0.5904 (N=133 for 20%, 129 for 5%). (k) Lifespan analysis of female gnmtMi flies under dietary restriction. Statistics, log-rank test, yw 20 versus 5%, P<0.0001 (N=140 for 20%, N=133 for 5%). gnmtMi 20 versus 5%, P=0.9107 (N=134 for 20%, 136 for 5%). *P<0.05, **P<0.01, ***P<0.001 from the biological replicates. NS, not significant.
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f3: Gnmt is necessary for lifespan extension by reduced insulin signalling or dietary restriction.(a) Lifespan analysis of Gnmt-overexpressing male flies by TubGS-Gal4. Statistics, log-rank test, gnmt versus gnmt+RU, P<0.0001 (N=117 for gnmt, N=118 for gnmt+RU). gnmtS145A versus gnmtS145A+RU, P=0.7732 (N=111 for gnmtS145A, N=113 for gnmtS145A+RU). (b,d,f,j,l) Average lifespan. One-way analysis of variance (ANOVA) with Bonferroni's multiple comparison test was used for statistical analysis. (c) Lifespan analysis of gnmt-overexpressing male and female flies by TubGS-Gal4. UAS-gnmt integrated on attP2 site is used. Statistics, log-rank test, gnmt-2 male versus gnmt-2+RU male, P<0.0001 (N=116 for each). gnmt-2 female versus gnmt-2+RU female, P<0.0001 (N=116 for each). (e) Lifespan analysis of male flies overexpressing InRDN (dominant-negative form of the insulin receptor), gnmt-RNAish or both. Statistics, log-rank test, InRDN versus InRDN+RU, P<0.0001 (N=158 for InRDN, N=154 for InRDN+RU). gnmt-RNAish versus gnmt-RNAish+RU, P=0.0478 (N=80 for both). InRDN, gnmt-RNAish versus InRDN, gnmt-RNAish+RU, P<0.0001 (N=142 for InRDN, gnmt-RNAish, N=154 for InRDN, gnmt-RNAish+RU). (g) qRT–PCR analysis of InR in day-7 adult male flies treated RU486 for 5 days. Error bars represent mean±s.e.m. (N=4). Statistics, one–way ANOVA with Bonferroni's multiple comparison test. (h) Lifespan analysis of male flies overexpressing sams. Statistics, log-rank test, sams versus sams+RU, P=0.6381 (N=135 for sams, N=143 for sams+RU). Inset, average lifespan. (i) Lifespan analysis of male gnmtMi flies under dietary restriction. Statistics, log-rank test, yw 20 versus 5%, P<0.0001 (N=134 for 20%, N=132 for 5%). gnmtMi 20 versus 5%, P=0.5904 (N=133 for 20%, 129 for 5%). (k) Lifespan analysis of female gnmtMi flies under dietary restriction. Statistics, log-rank test, yw 20 versus 5%, P<0.0001 (N=140 for 20%, N=133 for 5%). gnmtMi 20 versus 5%, P=0.9107 (N=134 for 20%, 136 for 5%). *P<0.05, **P<0.01, ***P<0.001 from the biological replicates. NS, not significant.

Mentions: We then assessed whether SAM reduction in gnmt-overexpressing flies had a positive impact on lifespan. When gnmt was overexpressed using TubGS-Gal4, we observed a slight but statistically significant increase in male lifespan (Fig. 3a,b). Several enzymes, including Gnmt, have functions other than enzymatic activity16, making us question whether Gnmt-induced longevity is dependent on its enzymatic activity. Overexpression of gnmtS145A by TubGS-Gal4 did not show any significant effect on lifespan, confirming that enhancing enzymatic activity of Gnmt is necessary for lifespan extension (Fig. 3a,b). Unexpectedly, we did not observe the lifespan increase in female flies when we compared lifespans of gnmt with those of gnmt+RU (Supplementary Fig. 3a,b). However, there was a significant increase in gnmt when compared with gnmtS145A, even in the absence of RU. It is possible that leaky expression of the TubGS driver was enough to extend lifespan in females, or that the position (attP40) effect of UAS-gnmt could have different effects on males and females. Therefore, we also checked the effect of Gnmt overexpression on lifespan using a different gnmt overexpression line, which was inserted at the attP2 site (gnmt-2). In line with this, we observed a significant increase in male and female lifespans (Fig. 3c,d), suggesting that Gnmt overexpression can be beneficial for both sexes.


Enhancing S-adenosyl-methionine catabolism extends Drosophila lifespan.

Obata F, Miura M - Nat Commun (2015)

Gnmt is necessary for lifespan extension by reduced insulin signalling or dietary restriction.(a) Lifespan analysis of Gnmt-overexpressing male flies by TubGS-Gal4. Statistics, log-rank test, gnmt versus gnmt+RU, P<0.0001 (N=117 for gnmt, N=118 for gnmt+RU). gnmtS145A versus gnmtS145A+RU, P=0.7732 (N=111 for gnmtS145A, N=113 for gnmtS145A+RU). (b,d,f,j,l) Average lifespan. One-way analysis of variance (ANOVA) with Bonferroni's multiple comparison test was used for statistical analysis. (c) Lifespan analysis of gnmt-overexpressing male and female flies by TubGS-Gal4. UAS-gnmt integrated on attP2 site is used. Statistics, log-rank test, gnmt-2 male versus gnmt-2+RU male, P<0.0001 (N=116 for each). gnmt-2 female versus gnmt-2+RU female, P<0.0001 (N=116 for each). (e) Lifespan analysis of male flies overexpressing InRDN (dominant-negative form of the insulin receptor), gnmt-RNAish or both. Statistics, log-rank test, InRDN versus InRDN+RU, P<0.0001 (N=158 for InRDN, N=154 for InRDN+RU). gnmt-RNAish versus gnmt-RNAish+RU, P=0.0478 (N=80 for both). InRDN, gnmt-RNAish versus InRDN, gnmt-RNAish+RU, P<0.0001 (N=142 for InRDN, gnmt-RNAish, N=154 for InRDN, gnmt-RNAish+RU). (g) qRT–PCR analysis of InR in day-7 adult male flies treated RU486 for 5 days. Error bars represent mean±s.e.m. (N=4). Statistics, one–way ANOVA with Bonferroni's multiple comparison test. (h) Lifespan analysis of male flies overexpressing sams. Statistics, log-rank test, sams versus sams+RU, P=0.6381 (N=135 for sams, N=143 for sams+RU). Inset, average lifespan. (i) Lifespan analysis of male gnmtMi flies under dietary restriction. Statistics, log-rank test, yw 20 versus 5%, P<0.0001 (N=134 for 20%, N=132 for 5%). gnmtMi 20 versus 5%, P=0.5904 (N=133 for 20%, 129 for 5%). (k) Lifespan analysis of female gnmtMi flies under dietary restriction. Statistics, log-rank test, yw 20 versus 5%, P<0.0001 (N=140 for 20%, N=133 for 5%). gnmtMi 20 versus 5%, P=0.9107 (N=134 for 20%, 136 for 5%). *P<0.05, **P<0.01, ***P<0.001 from the biological replicates. NS, not significant.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4595730&req=5

f3: Gnmt is necessary for lifespan extension by reduced insulin signalling or dietary restriction.(a) Lifespan analysis of Gnmt-overexpressing male flies by TubGS-Gal4. Statistics, log-rank test, gnmt versus gnmt+RU, P<0.0001 (N=117 for gnmt, N=118 for gnmt+RU). gnmtS145A versus gnmtS145A+RU, P=0.7732 (N=111 for gnmtS145A, N=113 for gnmtS145A+RU). (b,d,f,j,l) Average lifespan. One-way analysis of variance (ANOVA) with Bonferroni's multiple comparison test was used for statistical analysis. (c) Lifespan analysis of gnmt-overexpressing male and female flies by TubGS-Gal4. UAS-gnmt integrated on attP2 site is used. Statistics, log-rank test, gnmt-2 male versus gnmt-2+RU male, P<0.0001 (N=116 for each). gnmt-2 female versus gnmt-2+RU female, P<0.0001 (N=116 for each). (e) Lifespan analysis of male flies overexpressing InRDN (dominant-negative form of the insulin receptor), gnmt-RNAish or both. Statistics, log-rank test, InRDN versus InRDN+RU, P<0.0001 (N=158 for InRDN, N=154 for InRDN+RU). gnmt-RNAish versus gnmt-RNAish+RU, P=0.0478 (N=80 for both). InRDN, gnmt-RNAish versus InRDN, gnmt-RNAish+RU, P<0.0001 (N=142 for InRDN, gnmt-RNAish, N=154 for InRDN, gnmt-RNAish+RU). (g) qRT–PCR analysis of InR in day-7 adult male flies treated RU486 for 5 days. Error bars represent mean±s.e.m. (N=4). Statistics, one–way ANOVA with Bonferroni's multiple comparison test. (h) Lifespan analysis of male flies overexpressing sams. Statistics, log-rank test, sams versus sams+RU, P=0.6381 (N=135 for sams, N=143 for sams+RU). Inset, average lifespan. (i) Lifespan analysis of male gnmtMi flies under dietary restriction. Statistics, log-rank test, yw 20 versus 5%, P<0.0001 (N=134 for 20%, N=132 for 5%). gnmtMi 20 versus 5%, P=0.5904 (N=133 for 20%, 129 for 5%). (k) Lifespan analysis of female gnmtMi flies under dietary restriction. Statistics, log-rank test, yw 20 versus 5%, P<0.0001 (N=140 for 20%, N=133 for 5%). gnmtMi 20 versus 5%, P=0.9107 (N=134 for 20%, 136 for 5%). *P<0.05, **P<0.01, ***P<0.001 from the biological replicates. NS, not significant.
Mentions: We then assessed whether SAM reduction in gnmt-overexpressing flies had a positive impact on lifespan. When gnmt was overexpressed using TubGS-Gal4, we observed a slight but statistically significant increase in male lifespan (Fig. 3a,b). Several enzymes, including Gnmt, have functions other than enzymatic activity16, making us question whether Gnmt-induced longevity is dependent on its enzymatic activity. Overexpression of gnmtS145A by TubGS-Gal4 did not show any significant effect on lifespan, confirming that enhancing enzymatic activity of Gnmt is necessary for lifespan extension (Fig. 3a,b). Unexpectedly, we did not observe the lifespan increase in female flies when we compared lifespans of gnmt with those of gnmt+RU (Supplementary Fig. 3a,b). However, there was a significant increase in gnmt when compared with gnmtS145A, even in the absence of RU. It is possible that leaky expression of the TubGS driver was enough to extend lifespan in females, or that the position (attP40) effect of UAS-gnmt could have different effects on males and females. Therefore, we also checked the effect of Gnmt overexpression on lifespan using a different gnmt overexpression line, which was inserted at the attP2 site (gnmt-2). In line with this, we observed a significant increase in male and female lifespans (Fig. 3c,d), suggesting that Gnmt overexpression can be beneficial for both sexes.

Bottom Line: Overexpression of gnmt suppresses this age-dependent SAM increase and extends longevity.Pro-longevity regimens, such as dietary restriction or reduced insulin signalling, attenuate the age-dependent SAM increase, and rely at least partially on Gnmt function to exert their lifespan-extending effect in Drosophila.Our study suggests that regulation of SAM levels by Gnmt is a key component of lifespan extension.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.

ABSTRACT
Methionine restriction extends the lifespan of various model organisms. Limiting S-adenosyl-methionine (SAM) synthesis, the first metabolic reaction of dietary methionine, extends longevity in Caenorhabditis elegans but accelerates pathology in mammals. Here, we show that, as an alternative to inhibiting SAM synthesis, enhancement of SAM catabolism by glycine N-methyltransferase (Gnmt) extends the lifespan in Drosophila. Gnmt strongly buffers systemic SAM levels by producing sarcosine in either high-methionine or low-sams conditions. During ageing, systemic SAM levels in flies are increased. Gnmt is transcriptionally induced in a dFoxO-dependent manner; however, this is insufficient to suppress SAM elevation completely in old flies. Overexpression of gnmt suppresses this age-dependent SAM increase and extends longevity. Pro-longevity regimens, such as dietary restriction or reduced insulin signalling, attenuate the age-dependent SAM increase, and rely at least partially on Gnmt function to exert their lifespan-extending effect in Drosophila. Our study suggests that regulation of SAM levels by Gnmt is a key component of lifespan extension.

No MeSH data available.


Related in: MedlinePlus