Dietary restriction (DR) is the most effective and reproducible intervention to extend lifespan in divergent species1. In mammals, two regimens of DR, intermittent fasting (IF) and caloric restriction (CR), have proven to extend lifespan and reduce the incidence of age-related disorders2. An important characteristic of IF is that it can increase lifespan, even when there is little or no overall decrease in calorie intake2. The molecular mechanisms underlying IF-induced longevity, however, remain largely unknown. Here we establish an IF regimen that effectively extends the lifespan of Caenorhabditis elegans, and show that a nutrient-related signalling molecule, the low molecular weight GTPase Cel-Rheb, has a dual role in lifespan regulation; Cel-Rheb is required for the IF-induced longevity, whereas inhibition of Cel-Rheb mimics the CR effects. We also show that Cel-Rheb exerts its effects in part via the insulin/IGF-like signalling effector DAF-16 in IF, and that Cel-Rheb is required for fasting-induced nuclear translocation of DAF-16. We find that HSP-12.6, a DAF-16 target, functions to mediate the IF-induced longevity. Furthermore, our analyses demonstrate that most of fasting-induced upregulated genes require Cel-Rheb function for their induction, and that Cel-Rheb/Cel-TOR signalling is required for the fasting-induced downregulation of an insulin-like peptide, INS-7. These findings identify the essential role of signalling via Cel-Rheb in IF-induced longevity and gene expression changes, and suggest a molecular link between the IF-induced longevity and the insulin/IGF-like signalling pathway.
Signalling through RHEB-1 mediates intermittent fasting-induced longevity in C. elegans.
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The microRNA machinery regulates fasting-induced changes in gene expression and longevity in <i>Caenorhabditis elegans</i>.
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View SamplesIntermittent fasting (IF), a dietary restriction regimen, extends the lifespans of C. elegans and mammals by inducing gene expression changes. How fasting induces gene expression changes and longevity remains unclear. MicroRNAs (miRNAs) are small non-coding RNAs (approximately 22 nucleotides) that repress gene expression, and the expression of several miRNAs has been reported to be altered by fasting. In this study, we examined the role of the miRNA machinery in fasting-induced transcriptional changes and longevity in C. elegans. Our miRNA array analyses revealed that the expression levels of numerous miRNAs changed in adult worms after 48 hours of fasting. In addition to these changes, miRNA-mediated silencing complex (miRISC) components, including Argonaute proteins and GW182 proteins, and the miRNA-processing enzyme Drosha/DRSH-1, were up-regulated by fasting. Our lifespan measurements demonstrated that IF-induced longevity was suppressed by knockout or knockdown of miRISC components and was completely inhibited by drsh-1 ablation. Remarkably, drsh-1 ablation inhibited the fasting-induced changes in the expression of the target genes of DAF-16, the insulin/IGF-1 signaling effector. Fasting-induced transcriptome alterations were substantially and modestly suppressed in the drsh-1 null mutant and the null mutant of ain-1, a gene encoding GW182, respectively. These results indicate that components of the miRNA machinery, especially the miRNA-processing enzyme Drosha, play an important role in mediating IF-induced longevity via the regulation of fasting-induced gene expression changes.
The microRNA machinery regulates fasting-induced changes in gene expression and longevity in <i>Caenorhabditis elegans</i>.
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View SamplesDietary restriction regimens lead to enhanced stress resistance and extended lifespan in many species through the regulation of fasting and/or diet responsive mechanisms. The fasting stimulus is perceived by sensory neurons and causes behavioral and metabolic adaptations. Several studies have implicated that the nervous system is involved in the regulation of longevity. However, it remains largely unknown whether the nervous system contributes to the regulation of lifespan and/or stress resistance elicited by fasting. In this study, we first investigated the role of the nervous system in fasting-elicited longevity and stress resistance. We found that lifespan extension in Caenorhabditis elegans caused by an intermittent fasting (IF) regimen was suppressed by functional defects in sensory neurons. The IF-induced longevity was also suppressed in a mutant that lacks the enzyme required for the synthesis of an amine neurotransmitter, octopamine (OA), which acts in the absence of food, i.e., under fasting conditions. Although OA administration did not significantly extend the lifespan, it enhanced organismal resistance to oxidative stress. This enhanced resistance was suppressed by a mutation of the OA receptors, SER-3 and SER-6. Moreover, we found that OA administration promoted the nuclear translocation of DAF-16, the key transcription factor in fasting responses, and that the OA-induced enhancement of stress resistance required DAF-16. Altogether, our results suggest that OA signaling, which is triggered by the absence of food, shifts the organismal state to a more protective one to prepare for environmental stresses.
Octopamine enhances oxidative stress resistance through the fasting-responsive transcription factor DAF-16/FOXO in C. elegans.
Specimen part
View SamplesCholesterol has attracted significant attention as a possible lifespan regulator. It has been reported that serum cholesterol levels have an impact on mortality due to age-related disorders such as cardiovascular disease. Diet is also known to be an important lifespan regulator. Dietary restriction retards the onset of age-related diseases and extends lifespan in various organisms. Although cholesterol and dietary restriction are known to be lifespan regulators, it remains to be established whether cholesterol is involved in dietary restriction-induced longevity. Here, we show that cholesterol deprivation suppresses longevity induced by intermittent fasting, which is one of the dietary restriction regimens that effectively extend lifespan. We also found that cholesterol is required for the fasting-induced upregulation of transcriptional target genes such as the insulin/IGF-1 pathway effector DAF-16 and that cholesterol deprivation suppresses the long lifespan of the insulin/IGF-1 receptor daf-2 mutant. Remarkably, we found that cholesterol plays an important role in the fasting-induced nuclear accumulation of DAF-16. Moreover, knockdown of the cholesterol-binding protein NSBP-1, which has been shown to bind to DAF-16 in a cholesterol-dependent manner and to regulate DAF-16 activity, suppresses both fasting-induced longevity and DAF-16 nuclear accumulation. Furthermore, this suppression was not additive to the cholesterol deprivation-induced suppression, which suggests that NSBP-1 mediates, at least in part, the action of cholesterol to promote fasting-induced longevity and DAF-16 nuclear accumulation. These findings identify a novel role for cholesterol in the regulation of lifespan.
Cholesterol regulates DAF-16 nuclear localization and fasting-induced longevity in C. elegans.
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View SamplesWe report novel single-cell RNA-Seq, called Quartz-Seq. Quartz-Seq was simplified method compared with previous methods based on poly-A tailing reaction. Overall design: RNA-seq by illumina TruSeq, KAPA library preparation kit, single-cell Quartz-Seq and single-cell Smart-Seq by illumina HiSeq 2000/1000
Quartz-Seq: a highly reproducible and sensitive single-cell RNA sequencing method, reveals non-genetic gene-expression heterogeneity.
Specimen part, Disease
View SamplesCurcumin is a potent anti-inflammatory compound capable of preventing chemically induced colitis in mice.
Protective effects of dietary curcumin in mouse model of chemically induced colitis are strain dependent.
Treatment
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An improved single-cell cDNA amplification method for efficient high-density oligonucleotide microarray analysis.
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View SamplesThe inner cell mass (ICM) of the early blastocyst at E3.5, a source of ES cell derivation, is a morphologically homogeneous population of undifferentiated pluripotent cells that give rise to all embryonic lineages. The immediate application of the newly developed V1V3 method to single cells in this stage of mouse embryos revealed the presence of two populations of cells, one with primitive endoderm expression and the other with pluripotent epiblast-like gene expression. The genes expressed differentially between these two populations were well preserved in morphologically differentiated primitive endoderm and epiblast in the embryos one day later (E4.5), demonstrating that the method successfully detects subtle but essential differences in gene expression at the single-cell level among seemingly homogeneous cell populations. This study provides a strategy to analyze biophysical events in medicine as well as in neural, stem cell, and developmental biology, where small numbers of distinctive or diseased cells play critical roles.
An improved single-cell cDNA amplification method for efficient high-density oligonucleotide microarray analysis.
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View SamplesA systems-level understanding of a small but essential population of cells in development or adulthood (e.g., somatic stem cells) requires accurate quantitative monitoring of genome-wide gene expression, ideally from single cells. We report here a strategy to globally amplify mRNAs from single cells for highly quantitative high-density oligonucleotide microarray analysis that combines a small number of directional PCR cycles with subsequent linear amplification. Using this strategy, both the representation of gene expression profiles and reproducibility between individual experiments are unambiguously improved from the original method, along with high coverage and accuracy.
An improved single-cell cDNA amplification method for efficient high-density oligonucleotide microarray analysis.
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