Research ArticleORGANISMAL BIOLOGY

Genetic and pharmacological interventions in the aging motor nervous system slow motor aging and extend life span in C. elegans

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Science Advances  02 Jan 2019:
Vol. 5, no. 1, eaau5041
DOI: 10.1126/sciadv.aau5041
  • Fig. 1 slo-1 mutant worms exhibit a slower rate of motor activity decline during aging and are long lived.

    (A and B) slo-1(js379) mutant worms exhibit a slower rate of motor activity decline during aging. (A) slo-1(js379) and WT (N2) worms were analyzed for locomotion behavior every other day, and their locomotion speed was quantified. (B) Data summary for young (day 3) and aged (day 11) worms. Error bars represent SEM. n ≥ 15. **P < 0.005 and ***P < 0.0005 (t test). (C) slo-1(js379) mutant worms are long lived. See table S1 for details.

  • Fig. 2 SLO-1 acts in motor neurons to regulate both longevity and motor aging.

    (A) SLO-1 acts in motor neurons to regulate life span. Transgenic expression of slo-1 complementary DNA (cDNA) in neurons using a pan-neuronal promoter (rgef-1) and in motor neurons using a combination of acr-2 and unc-25 promoters rescued the longevity phenotype of slo-1 mutant worms, whereas such expression in muscles (myo-3 promoter) or sensory neurons (osm-6 promoter) did not. See table S1 for details. (B to F) SLO-1 acts in motor neurons to regulate motor aging. Transgenic expression of slo-1 cDNA in all neurons (B) and motor neurons (E), but not in the muscle (C) or sensory neurons (D), rescued the motor aging phenotype of slo-1 mutant worms in mid-late life. (B) to (E) share the same WT and slo-1 traces, which are listed for ease of comparison. (F) Bar graph summarizing the data in (B) to (E) of day 11 animals. Error bars represent SEM. n ≥ 15. *P < 0.05 and **P < 0.005 [analysis of variance (ANOVA) with Dunnett’s test]. n.s., not significant.

  • Fig. 3 Genetic knockdown of slo-1 in aged, but not young, worms slows motor aging and extends life span.

    (A to D) RNAi of slo-1 in young worms has no notable effect on motor aging (A and B), whereas this treatment in aged worms reduces the rate of motor activity decline in mid-late life (C and D). WT worms were fed bacteria expressing RNAi against slo-1 gene beginning at days 1 and 3 (A) or days 5 and 7 (C). (A) and (B) as well as (C) and (D) share the same vector control. (B) and (D) summarize the data in (A) and (C) for aged (day 11) animals, respectively. Error bars represent SEM. n ≥ 15. ***P < 0.0005 (ANOVA with Dunnett’s test). (E and F) slo-1 in young worms has no notable effect on their life span (E), whereas this treatment in aged worms extends life span (F). (E) and (F) share the same WT trace. RNAi was performed on TU3401, a neuron-specific RNAi strain (16). See table S1 for details.

  • Fig. 4 SLO-1 regulation of life span and motor aging requires the FOXO transcription factor DAF-16.

    (A) SLO-1 regulation of life span requires DAF-16. Loss of daf-16 blocked the long-lived phenotype of slo-1 mutant worms. (B) Transgenic expression of daf-16 cDNA in the intestine using the ges-1 promoter can fully rescue the daf-16 phenotype, whereas a neuron-specific transgene (rgef-1 promoter) only has a partial effect. No rescuing effect was observed with a muscle transgene (see fig. S5). (A) and (B) share the same slo-1 and slo-1;daf-16 curves. See table S1 for details. (C to E) SLO-1 regulation of motor aging requires DAF-16. Loss of daf-16 blocked the higher motor activity phenotype observed in aged slo-1 mutant worms (C), and this phenotype can be rescued by an intestinal daf-16 transgene (ges-1 promoter), only partially by a neuronal transgene (rgef-1 promoter), but not by a muscle transgene (myo-3 promoter) (D). (C) and (D) share the same slo-1 and slo-1;daf-16 curves. (E) Bar graph summarizing the data in (C) and (D) for aged (day 11) worms. Error bars represent SEM. n ≥ 15. **P < 0.005 and ***P < 0.0005 (ANOVA with Dunnett’s test).

  • Fig. 5 Pharmacological blockade of SLO-1 in aged, but not young, worms extends life span and slows motor aging.

    (A and B) Paxilline treatment of aged, but not young, worms extends life span. (A) Paxilline (10 nM) treatment from early age (days 1 and 3) did not extend life span (P < 0.348, log-rank test). (B) Paxilline (10 nM) treatment from aged worms (days 5 and 7) extended life span. See table S1 for statistics. (C) Paxilline extension of life span depends on SLO-1. No life-span extension by paxilline was detected in slo-1 mutant worms. See table S1 for details. (D to F) Paxilline treatment of aged, but not young, worms improves motor activity in mid-late life, which depends on SLO-1. (D) Paxilline treatment (10 nM) from early life (days 1 and 3) had no notable effect on age-dependent motor activity decline. (E) Paxilline (10 nM) treatment in aged worms (starting from days 5 and 7) reduced the rate of age-dependent motor activity decline and improved motor activity in mid-late life. (F) The effect of paxilline on motor aging depended on SLO-1, as no effect was detected in slo-1 mutant worms. (D) and (E) share the same WT curve. Error bars represent SEM. (G and H) Bar graphs in (G) and (H) summarizing the data in (D) and (E), and (F) of aged (day 11) WT and slo-1 mutant worms, respectively. Error bars represent SEM. n ≥ 15. ***P < 0.0005 (ANOVA with Dunnett’s test).

  • Fig. 6 Pharmacological inhibition of SLO-1 in aged worms promotes synaptic release from motor neurons at NMJs.

    (A) Synaptic release from motor neurons at NMJs is greatly reduced in aged worms and paxilline inhibition of SLO-1 can promote such release in aged worms. Sample traces of endogenous PSCs recorded from NMJs at the ventral nerve cord in young (day 3) and aged (day 9) worms with or without paxilline treatment (10 nM). Worms were treated with paxilline beginning at day 7, and their NMJs were recorded at day 9. Membrane voltage was clamped at −60 mV during recording. (B and C) Bar graphs summarizing the data in (A). (B) Frequency of endogenous PSCs. (C) Amplitude of endogenous PSCs. Error bars represent SEM. n ≥ 7. **P < 0.005 (ANOVA with Dunnett’s test). (D) Motor neurons show robust synaptic release at NMJs in aged slo-1 mutant worms, and paxilline treatment is unable to promote synaptic release from motor neurons in these mutant worms. Sample traces of endogenous PSCs recorded from NMJs at the ventral nerve cord in young (day 3) and aged (day 9) slo-1 worms with or without paxilline treatment (10 nM). Membrane voltage was clamped at −60 mV during recording. (E and F) Bar graphs summarizing the data in (D). (E) Frequency of endogenous PSCs. (F) Amplitude of endogenous PSCs. Error bars represent SEM. n ≥ 7.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/1/eaau5041/DC1

    Fig. S1. slo-1 mutant worms exhibit slower locomotor activity decline throughout life span.

    Fig. S2. slo-1 gain-of-function mutation greatly shortens life span.

    Fig. S3. DAF-16 target gene expression and DAF-16 nuclear translocation in slo-1 mutant worms.

    Fig. S4. slo-1 and IIS act in parallel to regulate life span.

    Fig. S5. Expression of daf-16 cDNA in the muscle fails to rescue the daf-16 mutant phenotype.

    Fig. S6. The effects of different concentrations of paxilline on life span and motor aging.

    Fig. S7. Loss of slo-1 does not extend the life span of mutants defective in neurotransmission.

    Table S1. Summary of life-span data.

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. slo-1 mutant worms exhibit slower locomotor activity decline throughout life span.
    • Fig. S2. slo-1 gain-of-function mutation greatly shortens life span.
    • Fig. S3. DAF-16 target gene expression and DAF-16 nuclear translocation in slo-1 mutant worms.
    • Fig. S4. slo-1 and IIS act in parallel to regulate life span.
    • Fig. S5. Expression of daf-16 cDNA in the muscle fails to rescue the daf-16 mutant phenotype.
    • Fig. S6. The effects of different concentrations of paxilline on life span and motor aging.
    • Fig. S7. Loss of slo-1 does not extend the life span of mutants defective in neurotransmission.
    • Table S1. Summary of life-span data.

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