Project description:Intermittent fasting (IF) is a dietary restriction regimen that extends the lifespans of Caenorhabditis elegans and mammals by inducing changes in gene expression. However, how IF induces these changes and promotes longevity remains unclear. One proposed mechanism involves gene regulation by microRNAs (miRNAs), small non-coding RNAs (∼22 nucleotides) that repress gene expression and whose expression can be altered by fasting. To test this proposition, we examined the role of the miRNA machinery in fasting-induced transcriptional changes and longevity in C. elegans We revealed that fasting up-regulated the expression of the miRNA-induced silencing complex (miRISC) components, including Argonaute and GW182, and the miRNA-processing enzyme DRSH-1 (the ortholog of the Drosophila Drosha enzyme). Our lifespan measurements demonstrated that IF-induced longevity was suppressed by knock-out 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 in C. elegans 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. Moreover, miRNA array analyses revealed that the expression levels of numerous miRNAs changed after 2 days of fasting. These results indicate that components of the miRNA machinery, especially the miRNA-processing enzyme DRSH-1, play an important role in mediating IF-induced longevity via the regulation of fasting-induced changes in gene expression.
Project description:Intermittent 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. To validate the involvement of drsh-1, ain-1 and daf-16 in fasting-induced gene expression changes, we compared the induction rates of all genes in the mutants with the induction rates of all genes in WT worms
Project description:Intermittent 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. To examine the fasting-induced changes in miRNA expression in adult worms, we performed miRNA array experiments.
Project description:Cholesterol 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. Two independent replicates were performed. Total RNA was extracted with TRIzol (Invitrogen). The extracted RNA was purified with PureLink RNA Micro Kit (Invitrogen) and analyzed with Agilent 2100 Bioanalyzer to assess the RNA integrity. The microarray procedures were performed according to Affymetrix protocols. Hybridized arrays were scanned using an Affymetrix GeneChip Scanner.
Project description:Neither genetic nor environmental factors fully account for variability in individual longevity: genetically identical invertebrates in homogenous environments often experience no less variability in lifespan than outbred human populations. Such variability is often assumed to result from stochasticity in damage accumulation over time; however, the identification of early-life gene expression states that predict future longevity would suggest that lifespan is least in part epigenetically determined. Such "biomarkers of aging," genetic or otherwise, nevertheless remain rare. In this work, we sought early-life differences in organismal robustness in unperturbed individuals and examined the utility of microRNAs, known regulators of lifespan, development, and robustness, as aging biomarkers. We quantitatively examined Caenorhabditis elegans reared individually in a novel apparatus and observed throughout their lives. Early-to-mid-adulthood measures of homeostatic ability jointly predict 62% of longevity variability. Though correlated, markers of growth/muscle maintenance and of metabolic by-products ("age pigments") report independently on lifespan, suggesting that graceful aging is not a single process. We further identified three microRNAs in which early-adulthood expression patterns individually predict up to 47% of lifespan differences. Though expression of each increases throughout this time, mir-71 and mir-246 correlate with lifespan, while mir-239 anti-correlates. Two of these three microRNA "biomarkers of aging" act upstream in insulin/IGF-1-like signaling (IIS) and other known longevity pathways, thus we infer that these microRNAs not only report on but also likely determine longevity. Thus, fluctuations in early-life IIS, due to variation in these microRNAs and from other causes, may determine individual lifespan.
Project description:Cholesterol 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.