Temporally controlled nervous system-to-gut signaling bidirectionally regulates longevity in C. elegans

Lingxiu Xu
Chengxuan Han
Lei Chun author has email address
X.Z. Shawn Xu author has email address
Jianfeng Liu author has email address

College of Life Science and Technology, Key Laboratory of Molecular Biophysics of MOE, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
Life Sciences Institute and Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, U.S.A.

https://doi.org/10.7554/eLife.97829.1

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Figures and data

Cholinergic motor neurons differentially regulate lifespan at different stages of worm life.
(A) Ablating the output of cholinergic motor neurons promotes survival at early life stage, whereas inhibits survival at later stages. Tetanus toxin (TeTx) was expressed as a transgene in cholinergic motor neurons using acr-2 promoter to block exocytosis from these neurons.
(B) Promoting the output of cholinergic motor neurons shortens lifespan. The gain-of-function form of Drosophila syntaxin(T254I) was expressed as a transgene in cholinergic motor neurons using acr-2 promotor to potentiate exocytosis from these neurons.
(C) Schematic describing the assay. The gain-of-function form of Drosophila syntaxin(T254I) fused with a degron tag was expressed as a transgene in cholinergic motor neurons to promote exocytosis from these neurons. Transgenic worms were then crossed with a line stably expressing TIR1 in these neurons. Expression of Syntaxin(T254I) was suppressed by 0.5 mM auxin treatment and induced by subsequently removing auxin.
(D) Syntaxin(T254I) transgene has slight effect on lifespan when suppressing its expression throughout the entire worm life.
(E) Syntaxin(T254I) transgene shortens lifespan when inducing its expression throughout the entire worm life.
(F) Syntaxin(T254I) transgene shortens lifespan when inducing its expression from egg to L4 larval stage.
(G-I) Syntaxin(T254I) transgene modestly affects lifespan when inducing its expression from L4 larval stage (G), Day 3 (H) or Day 5 (I) adulthood.
(J-K) Syntaxin(T254I) transgene extends lifespan when inducing its expression from Day 7 (J), Day 9 (K) or Day 11 (L) adulthood. See Table S1 for detailed statistical analysis of lifespan data. Logrank (Kaplan-Meier) was used to calculate p values.

ACh and the nicotinic AChR ACR-6 mediate the lifespan-shortening effect of cholinergic motor neurons in early life.
(A) Syntaxin(T254I) transgene shortens lifespan.
(B) Loss of unc-31 exhibits no defect on the ability of syntaxin(T254I) transgene to shorten lifespan.
(C) Loss of unc-17 blocks the ability of syntaxin(T254I) transgene to shorten lifespan
(D-F) Loss of acr-6 blocks the ability of syntaxin(T254I) transgene to shorten lifespan (D), a phenotype rescued by transgenic expression of wild-type acr-6 gene in the intestine (E), but not in neurons (F). The ges-1 and rgef-1 promoters were used to drive acr-6 gene expression in the intestine and neurons, respectively. See Table S1 for detailed statistical analysis of lifespan data. Logrank (Kaplan-Meier) was used to calculate p values.

The FOXO transcription factor DAF-16 is required in the intestine for cholinergic motor neurons to regulate lifespan in early life.
(A) Syntaxin(T254I) transgene shortens lifespan.
(B-E) RNAi of daf-16 does not further shorten the lifespan of syntaxin(T254I) transgenic worms, while RNAi of hsf-1 (C), skn-1 (D) and pha-4 (E) does.
(F) qPCR analysis of DAF-16 target genes. qPCR reactions were run in triplicates for each genotype. Each experiment was repeated three times. Error bars represent s.e.m. ****p< 0.0001 (ANOVA with Bonferroni’s test).
(G-H) RNAi of daf-16 in the intestine (H) abolishes the ability of TeTx transgene to regulate lifespan (G). dsRNA against daf-16 was expressed as a transgene specifically in the intestine using vha-6 promoter. These experiments were carried out in a sid-1 mutant background where systemic effect of RNAi is absent. See Table S1 for detailed statistical analysis of lifespan data. Log-rank (Kaplan-Meier) was used to calculate p values.

ACh and the intestinal muscarinic AChR GAR-3 mediate the lifespan-extending effect of cholinergic motor neurons in mid-late life.
(A) Enhancing the output of cholinergic motor neurons in mid-late life extends lifespan. The syntaxin(T254I) transgene was induced from Day 7 adulthood as described in Figure 1C.
(B-C) Loss of unc-17 (B) or gar-3 (C) blocks the ability of cholinergic motor neurons to extend lifespan in mid-late life.
(D-F) RNAi of gar-3 in the intestine (E), but not in neurons (F), abolishes the ability of cholinergic motor neurons to extend lifespan in mid-late life (D). dsRNA against gar-3 was expressed as a transgene specifically in the intestine and neurons using ges-1 and rgef-1 promoter, respectively. These experiments were carried out in a sid-1 mutant background where systemic effect of RNAi is absent. See Table S1 for detailed statistical analysis of lifespan data. Log-rank (Kaplan-Meier) was used to calculate p values.

The transcription factor HSF-1 is required in the intestine for cholinergic motor neurons to regulate lifespan in mid-late life.
(A-B) Enhancing the output of cholinergic motor neurons in mid-late life extends lifespan (A). This effect was fully suppressed by RNAi of hsf-1 (B). The syntaxin(T254I) transgene was induced from Day 7 adulthood as described in Figure 1C.
(C) qPCR analysis of HSF-1 target genes. qPCR reactions were run in triplicates for each genotype. Each experiment was repeated three times. Error bars represent s.e.m. ****p< 0.0001 (ANOVA with Bonferroni’s test).
(D-F) RNAi of hsf-1 in the intestine (E), but not in neurons (F), abolishes the ability of cholinergic motor neurons to extend lifespan in mid-late life (D). dsRNA against hsf-1 was expressed as a transgene specifically in the intestine and neurons using ges-1 and rgef-1 promoter, respectively. These experiments were carried out in a sid-1 mutant background where systemic effect of RNAi is absent. See Table S1 for detailed statistical analysis of lifespan data. Logrank (Kaplan-Meier) was used to calculate p values.

Temporal control of ACR-6 and GAR-3 expression in the intestine at different life stages.
(A-B) The expression pattern of endogenous ACR-6 and GAR-3 proteins at L3 Larva stage (A) and Day 2 adult stage (B). Arrowheads point to the area of the intestine. Scale bars, 20 μm.
(C) Quantification curves summarizing the data in (A) and (B). Error bars represent s.e.m. n ≥ 10.
(D) A schematic model illustrating the two cholinergic motor neurons-to-gut signaling circuits that act in early life to shorten lifespan and in mid-late life to extend lifespan.

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