Project description: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.
Project description: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. Experiment Overall Design: We examined fasting-induced changes of the gene expression profiles in Caenorhabditis elegans. We performed the genome-wide analysis by using Affymetrix GeneChip oligonucleotide microarrays, and examined the effect of downregulation of Cel-Rheb and Cel-TOR by RNAi on the expression profiles. Five independent experiments were performed with wild type N2. Synchronized worms under six conditions (control-fed, control-fasting, Rheb RNAi-fed, Rheb RNAi-fasting, TOR RNAi-fed, and TOR RNAi-fasting) were collected and frozen with liquid nitrogen at day 4 of adulthood. Total RNA was extracted with Sepasol(R)-RNA â Super (Nacalai tesque), and purified with RNeasy Mini Kit (Qiagen), according to manufactureâs instructions. Synthesis of cDNA, in vitro transcription and biotin labelling cRNA, and hybridization to the C. elegans Genome Array (Affymetrix) were performed according to Affymetrix protocols. Hybridized arrays were scanned using an Affymetrix GeneChip Scanner. Scanned chip images were analyzed with GeneSpring GX 7.3.1 (Agilent Technologies).
Project description:In order to understand the complexity of gene regulation downstream of IIS, we used anti-DAF-16 antibody, we report the first genome-wide ChIP-sequencing study of endogenous DAF-16 recruitment in daf-2(e1370). We also report the average bin-wise normalized read count of ZFP-1 and DAF-16 on DAF-16 summits
Project description:Transcriptome profiling of three models with impaired insulin/IGF1 signaling. 1. Deep sequencing of endogenous mRNA from Caenorhabditis elegans N2 var. Bristol (wildtype) and daf-2(e1370) mutant; 2. Deep sequencing of endogenous mRNA from murine embryonic fibroblasts (MEF) wildtype and irs1-/- knockout; 3. Deep sequencing of endogenous mRNA from murine embryoinic fibroblast (MEF) insr+/- -lox and insr+/- knockout 14 samples examined: C. elegans N2 var. Bristol (wildtype) vs. daf-2(e1370) mutant; MEF wildtype vs. irs1-/- knockout; MEF insr+/- -lox vs. insr +/- knockout
Project description:In order to understand the complexity of gene regulation downstream of IIS, we used anti-DAF-16 antibody, we report the first genome-wide ChIP-sequencing study of endogenous DAF-16 recruitment in daf-2(e1370). We also report the average bin-wise normalized read count of ZFP-1 and DAF-16 on DAF-16 summits ChIP-Seq profile of DAF-16 in mix stage
Project description:Insulin/IGF-1 Signaling (IIS) is known to constrain longevity by inhibiting the transcription factor FOXO. How phosphorylation mediated by IIS kinases regulates lifespan beyond FOXO remains unclear. Here, we profile IIS-dependent phosphorylation changes in a large-scale quantitative phosphoproteomic analysis of wild-type and three IIS mutant Caenorhabditis elegans strains. We quantify more than 15,000 phosphosites and find that 476 of these are differentially phosphorylated in the long-lived daf-2/insulin receptor mutant. We develop a machine learning-based method to prioritize 25 potential lifespan-related phosphosites. We perform validations to show that AKT-1 pT492 inhibits DAF-16/FOXO and compensates the loss of daf-2 function, that EIF-2α pS49 potently inhibits protein synthesis and daf-2 longevity, and that reduced phosphorylation of multiple germline proteins apparently transmits reduced DAF-2 signaling to the soma. In addition, an analysis of kinases with enriched substrates detects that casein kinase 2 (CK2) subunits negatively regulate lifespan. Our study reveals detailed functional insights into longevity.
Project description:In this study we have investigated the effect of loss of math-33 activity on DAF-16-mediated target gene regulation in C. elegans under conditions of reduced Insulin/IGF-1 signaling (IIS). Using whole nematode RNA sequencing experiments we found that the daf-2(e1370)-mediated induction and repression of DAF-16 target genes was decreased in daf-2(e1370); math-33(tm3561) mutant animals. Our data suggest that the downregulation of endogenous DAF-16 isoforms in the absence of a functional MATH-33 severely affects the global expression of DAF-16 targets when IIS activity is reduced. Therefore, MATH-33 is essential for DAF-16-mediated target gene activation and repression in the context of IIS.
Project description:We confirmed that the life span of C. elegans feeding hns mutant E. coli was increased. hns mutant E. coli was found to regulate lifespan of C. elegans through daf-16 activation in C. elegans. It is well known that daf-16 is the transcription factor of the insulin/IGF-1 signaling pathway and it is known to regulate downstream genes such as longevity, stress response, and dauer diapause regulation genes. Thus, we performed Next Generation Sequencing(NGS) to investigate the downstream genes regulated by daf-16 in C. elegans that are activated by hns mutant E. coli. N2 wild type worms and daf-16 mutant worms were fed with BW25113 wild type E. coli and hns mutant E. coli, respectively, and then NGS was performed by harvesting the worms and purifying the RNA. We investigated how the downstream genes of daf-16 of C. elegans, which is regulated by hns mutant E. coli, differs from the downstream genes of daf-16 of C. elegans, which is regulated by the insulin/IGF-1 signaling pathway. To do this, we carried out the analysis including two previous studied papers that analyzed the daf-16 downstream genes related to the insulin/IGF-1 signaling pathway. Surprisingly, only 6 genes were up-regulated in all three experiments and 288 genes were found to be dependent on daf-16 and hns mutant E. coli. This study indicated that hns mutant E. coli regulate daf-16 distinct from insulin/IGF-1 signaling pathway on C. elegans.