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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.


SAM levels increased during ageing in spite of induced gnmt expression by dFoxO in fat body.(a–d) UPLC–MS/MS analysis of SAM and Met levels in wild-type male flies during ageing. Error bars represent mean±s.d. (N=4). Statistics, one-way analysis of variance (ANOVA) with Bonferroni's multiple comparison test. (e) UPLC–MS/MS analysis of sarcosine levels in male w1118 during ageing. Error bars represent mean±s.d. (N=3). Statistics, one-way ANOVA with Bonferroni's multiple comparison test. (f) Western blot analysis of Sardh and Gnmt during ageing in male w1118. (g,h) qRT–PCR analysis of gnmt and sardh in young (1 week old) and old (7 weeks old) wild-type male flies. Error bars represent mean±s.e.m. (N=5 for 1 w w1118, N=6 for 7 w w1118, N=3 for Canton S). Statistics, two-tailed unpaired t-test 1 versus 7 w. (i) UPLC–MS/MS analysis of sarcosine levels in young and old male flies with lacZ-RNAi or sardh-RNAi. Error bars represent mean±s.d. (N=4). Statistics, One-way ANOVA with Bonferroni's multiple comparison test. (j) Western blot analysis of Gnmt in dFoxO knockdown flies.+ Indicates Gal4-only controls. (k) UPLC–MS/MS analysis of SAM levels in young and old male flies with lacZ-RNAi, dFoxO-RNAi, gnmt or gnmtS145A. Error bars represent mean±s.d. (N=4). Statistics, one-way ANOVA with Bonferroni's multiple comparison test. w, week. *P<0.05, **P<0.01, ***P<0.001 from the biological replicates.
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f4: SAM levels increased during ageing in spite of induced gnmt expression by dFoxO in fat body.(a–d) UPLC–MS/MS analysis of SAM and Met levels in wild-type male flies during ageing. Error bars represent mean±s.d. (N=4). Statistics, one-way analysis of variance (ANOVA) with Bonferroni's multiple comparison test. (e) UPLC–MS/MS analysis of sarcosine levels in male w1118 during ageing. Error bars represent mean±s.d. (N=3). Statistics, one-way ANOVA with Bonferroni's multiple comparison test. (f) Western blot analysis of Sardh and Gnmt during ageing in male w1118. (g,h) qRT–PCR analysis of gnmt and sardh in young (1 week old) and old (7 weeks old) wild-type male flies. Error bars represent mean±s.e.m. (N=5 for 1 w w1118, N=6 for 7 w w1118, N=3 for Canton S). Statistics, two-tailed unpaired t-test 1 versus 7 w. (i) UPLC–MS/MS analysis of sarcosine levels in young and old male flies with lacZ-RNAi or sardh-RNAi. Error bars represent mean±s.d. (N=4). Statistics, One-way ANOVA with Bonferroni's multiple comparison test. (j) Western blot analysis of Gnmt in dFoxO knockdown flies.+ Indicates Gal4-only controls. (k) UPLC–MS/MS analysis of SAM levels in young and old male flies with lacZ-RNAi, dFoxO-RNAi, gnmt or gnmtS145A. Error bars represent mean±s.d. (N=4). Statistics, one-way ANOVA with Bonferroni's multiple comparison test. w, week. *P<0.05, **P<0.01, ***P<0.001 from the biological replicates.

Mentions: Although Gnmt overexpression extended longevity, and Gnmt is required for DR-induced longevity, it is still unknown whether Gnmt activity and SAM metabolism changes during physiological ageing. We quantified Met and SAM in two different wild-type strains analysing both young and aged male flies. Met levels decreased during ageing, whereas SAM levels increased (Fig. 4a–d). We also found that the amount of sarcosine decreased during ageing (Fig. 4e), suggesting Gnmt activity to buffer SAM declines in an age-dependent manner. However, the expression of Gnmt was induced in aged male flies, as determined by quantitative real-time PCR (qRT–PCR) and western blotting using whole-body homogenates (Fig. 4f,g; Supplementary Fig. 4a). Sarcosine levels are negatively regulated by sarcosine dehydrogenase (sardh)12, and Sardh was also induced transcriptionally during ageing (Fig. 4f,h). Interestingly, when sardh expression was knocked down, sarcosine levels were high in young male flies and further induced by ageing (Fig. 4i), suggesting that total Gnmt activity is indeed increased during ageing. Gnmt was increased in the fat body, because fat-body-specific knockdown of gnmt abrogated elevation of Gnmt in whole-body homogenates (Supplementary Fig. 4b). This increase was dependent on dFoxO (Fig. 4j; Supplementary Fig. 4c). Induction of Gnmt expression during ageing might be an adaptive response against an increase in SAM levels. Indeed, when dFoxO was knocked down in the fat body, SAM levels in aged male flies were further elevated (Fig. 4k). Therefore, we concluded that the dFoxO–Gnmt pathway is activated, but not sufficiently for complete suppression of the SAM increase in aged flies. Importantly, overexpression of gnmt, but not gnmtS145A, inhibited the age-dependent SAM increase (Fig. 4k; Supplementary Fig. 4d,e), indicating that Gnmt-induced lifespan extension is caused by suppression of the age-dependent increase in SAM.


Enhancing S-adenosyl-methionine catabolism extends Drosophila lifespan.

Obata F, Miura M - Nat Commun (2015)

SAM levels increased during ageing in spite of induced gnmt expression by dFoxO in fat body.(a–d) UPLC–MS/MS analysis of SAM and Met levels in wild-type male flies during ageing. Error bars represent mean±s.d. (N=4). Statistics, one-way analysis of variance (ANOVA) with Bonferroni's multiple comparison test. (e) UPLC–MS/MS analysis of sarcosine levels in male w1118 during ageing. Error bars represent mean±s.d. (N=3). Statistics, one-way ANOVA with Bonferroni's multiple comparison test. (f) Western blot analysis of Sardh and Gnmt during ageing in male w1118. (g,h) qRT–PCR analysis of gnmt and sardh in young (1 week old) and old (7 weeks old) wild-type male flies. Error bars represent mean±s.e.m. (N=5 for 1 w w1118, N=6 for 7 w w1118, N=3 for Canton S). Statistics, two-tailed unpaired t-test 1 versus 7 w. (i) UPLC–MS/MS analysis of sarcosine levels in young and old male flies with lacZ-RNAi or sardh-RNAi. Error bars represent mean±s.d. (N=4). Statistics, One-way ANOVA with Bonferroni's multiple comparison test. (j) Western blot analysis of Gnmt in dFoxO knockdown flies.+ Indicates Gal4-only controls. (k) UPLC–MS/MS analysis of SAM levels in young and old male flies with lacZ-RNAi, dFoxO-RNAi, gnmt or gnmtS145A. Error bars represent mean±s.d. (N=4). Statistics, one-way ANOVA with Bonferroni's multiple comparison test. w, week. *P<0.05, **P<0.01, ***P<0.001 from the biological replicates.
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Related In: Results  -  Collection

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f4: SAM levels increased during ageing in spite of induced gnmt expression by dFoxO in fat body.(a–d) UPLC–MS/MS analysis of SAM and Met levels in wild-type male flies during ageing. Error bars represent mean±s.d. (N=4). Statistics, one-way analysis of variance (ANOVA) with Bonferroni's multiple comparison test. (e) UPLC–MS/MS analysis of sarcosine levels in male w1118 during ageing. Error bars represent mean±s.d. (N=3). Statistics, one-way ANOVA with Bonferroni's multiple comparison test. (f) Western blot analysis of Sardh and Gnmt during ageing in male w1118. (g,h) qRT–PCR analysis of gnmt and sardh in young (1 week old) and old (7 weeks old) wild-type male flies. Error bars represent mean±s.e.m. (N=5 for 1 w w1118, N=6 for 7 w w1118, N=3 for Canton S). Statistics, two-tailed unpaired t-test 1 versus 7 w. (i) UPLC–MS/MS analysis of sarcosine levels in young and old male flies with lacZ-RNAi or sardh-RNAi. Error bars represent mean±s.d. (N=4). Statistics, One-way ANOVA with Bonferroni's multiple comparison test. (j) Western blot analysis of Gnmt in dFoxO knockdown flies.+ Indicates Gal4-only controls. (k) UPLC–MS/MS analysis of SAM levels in young and old male flies with lacZ-RNAi, dFoxO-RNAi, gnmt or gnmtS145A. Error bars represent mean±s.d. (N=4). Statistics, one-way ANOVA with Bonferroni's multiple comparison test. w, week. *P<0.05, **P<0.01, ***P<0.001 from the biological replicates.
Mentions: Although Gnmt overexpression extended longevity, and Gnmt is required for DR-induced longevity, it is still unknown whether Gnmt activity and SAM metabolism changes during physiological ageing. We quantified Met and SAM in two different wild-type strains analysing both young and aged male flies. Met levels decreased during ageing, whereas SAM levels increased (Fig. 4a–d). We also found that the amount of sarcosine decreased during ageing (Fig. 4e), suggesting Gnmt activity to buffer SAM declines in an age-dependent manner. However, the expression of Gnmt was induced in aged male flies, as determined by quantitative real-time PCR (qRT–PCR) and western blotting using whole-body homogenates (Fig. 4f,g; Supplementary Fig. 4a). Sarcosine levels are negatively regulated by sarcosine dehydrogenase (sardh)12, and Sardh was also induced transcriptionally during ageing (Fig. 4f,h). Interestingly, when sardh expression was knocked down, sarcosine levels were high in young male flies and further induced by ageing (Fig. 4i), suggesting that total Gnmt activity is indeed increased during ageing. Gnmt was increased in the fat body, because fat-body-specific knockdown of gnmt abrogated elevation of Gnmt in whole-body homogenates (Supplementary Fig. 4b). This increase was dependent on dFoxO (Fig. 4j; Supplementary Fig. 4c). Induction of Gnmt expression during ageing might be an adaptive response against an increase in SAM levels. Indeed, when dFoxO was knocked down in the fat body, SAM levels in aged male flies were further elevated (Fig. 4k). Therefore, we concluded that the dFoxO–Gnmt pathway is activated, but not sufficiently for complete suppression of the SAM increase in aged flies. Importantly, overexpression of gnmt, but not gnmtS145A, inhibited the age-dependent SAM increase (Fig. 4k; Supplementary Fig. 4d,e), indicating that Gnmt-induced lifespan extension is caused by suppression of the age-dependent increase in SAM.

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.