Project description:The plasticity of ageing suggests that longevity may be controlled epigenetically by specific alterations in chromatin state. The link between chromatin and ageing has mostly focused on histone deacetylation by the Sir2 family1, 2, but less is known about the role of other histone modifications in longevity. Histone methylation has a crucial role in development and in maintaining stem cell pluripotency in mammals3. Regulators of histone methylation have been associated with ageing in worms4, 5, 6, 7 and flies8, but characterization of their role and mechanism of action has been limited. Here we identify the ASH-2 trithorax complex9, which trimethylates histone H3 at lysine 4 (H3K4), as a regulator of lifespan in Caenorhabditis elegans in a directed RNA interference (RNAi) screen in fertile worms. Deficiencies in members of the ASH-2 complex—ASH-2 itself, WDR-5 and the H3K4 methyltransferase SET-2—extend worm lifespan. Conversely, the H3K4 demethylase RBR-2 is required for normal lifespan, consistent with the idea that an excess of H3K4 trimethylation—a mark associated with active chromatin—is detrimental for longevity. Lifespan extension induced by ASH-2 complex deficiency requires the presence of an intact adult germline and the continuous production of mature eggs. ASH-2 and RBR-2 act in the germline, at least in part, to regulate lifespan and to control a set of genes involved in lifespan determination. These results indicate that the longevity of the soma is regulated by an H3K4 methyltransferase/demethylase complex acting in the C. elegans germline. There are 23 samples in total. ASH-2 knock-down increases lifespan in a germline dependent manner. We examined ASH-2 regulated genes that are dependent on the presence of an intact germline using WT or glp-1(e2141ts) mutant worms which develop only 5-15 meiotic germ cells treated with either empty vector (EV) or ash-2 RNAi. We examined gene expression at the L3 stage (when we observe changes in H3K4me3) and at a mid life stage (day 8). The majority of ASH-2 controlled genes were regulated in a germline dependent manner. Samples were collected in triplicate for each condition (but Day 8 N2 (WT) E.V. #3 was excluded from all analysis due to quality issues).
Project description:Chromatin modifiers regulate lifespan in several organisms, raising the question of whether changes in chromatin states in the parental generation could be incompletely reprogrammed in the next generation and thereby affect the lifespan of descendents. The histone H3 lysine 4 trimethylation (H3K4me3) complex composed of ASH-2, WDR-5, and the histone methyltransferase SET-2 regulates C. elegans lifespan. Here we show that deficiencies in the H3K4me3 chromatin modifiers ASH-2, WDR-5, or SET-2 in the parental generation extend the lifespan of descendents up until the third generation. The transgenerational inheritance of lifespan extension by members of the ASH-2 complex is dependent on the H3K4me3 demethylase RBR-2, and requires the presence of a functioning germline in the descendents. Transgenerational inheritance of lifespan is specific for the H3K4me3 methylation complex and is associated with epigenetic changes in gene expression. Thus, manipulation of specific chromatin modifiers only in parents can induce an epigenetic memory of longevity in descendents.
Project description:The plasticity of ageing suggests that longevity may be controlled epigenetically by specific alterations in chromatin state. The link between chromatin and ageing has mostly focused on histone deacetylation by the Sir2 family1, 2, but less is known about the role of other histone modifications in longevity. Histone methylation has a crucial role in development and in maintaining stem cell pluripotency in mammals3. Regulators of histone methylation have been associated with ageing in worms4, 5, 6, 7 and flies8, but characterization of their role and mechanism of action has been limited. Here we identify the ASH-2 trithorax complex9, which trimethylates histone H3 at lysine 4 (H3K4), as a regulator of lifespan in Caenorhabditis elegans in a directed RNA interference (RNAi) screen in fertile worms. Deficiencies in members of the ASH-2 complex—ASH-2 itself, WDR-5 and the H3K4 methyltransferase SET-2—extend worm lifespan. Conversely, the H3K4 demethylase RBR-2 is required for normal lifespan, consistent with the idea that an excess of H3K4 trimethylation—a mark associated with active chromatin—is detrimental for longevity. Lifespan extension induced by ASH-2 complex deficiency requires the presence of an intact adult germline and the continuous production of mature eggs. ASH-2 and RBR-2 act in the germline, at least in part, to regulate lifespan and to control a set of genes involved in lifespan determination. These results indicate that the longevity of the soma is regulated by an H3K4 methyltransferase/demethylase complex acting in the C. elegans germline.
Project description:Chromatin modifiers regulate lifespan in several organisms, raising the question of whether changes in chromatin states in the parental generation could be incompletely reprogrammed in the next generation and thereby affect the lifespan of descendents. The histone H3 lysine 4 trimethylation (H3K4me3) complex composed of ASH-2, WDR-5, and the histone methyltransferase SET-2 regulates C. elegans lifespan. Here we show that deficiencies in the H3K4me3 chromatin modifiers ASH-2, WDR-5, or SET-2 in the parental generation extend the lifespan of descendents up until the third generation. The transgenerational inheritance of lifespan extension by members of the ASH-2 complex is dependent on the H3K4me3 demethylase RBR-2, and requires the presence of a functioning germline in the descendents. Transgenerational inheritance of lifespan is specific for the H3K4me3 methylation complex and is associated with epigenetic changes in gene expression. Thus, manipulation of specific chromatin modifiers only in parents can induce an epigenetic memory of longevity in descendents. There are 35 samples in total. We found that genetically WT descendents from mutants of the H3K4me3 modifying complex had extended longevity up until the F4 generation. Their lifespan returned to WT levels in the F5 generation. We performed microarrays to examine what gene expression differences there were between N2(WT) worms, +/+ (from wdr-5 mutant) worms, and wdr-5/wdr-5 in the F4 and the F5 generation. We analyzed L3 samples from the first and second days of egg laying in triplicate each. Samples consist of ~1000 worms each.
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:Epigenetic modifications are thought to be important for gene expression changes during development and aging. However, besides the Sir2 histone deacetylase in somatic tissues and H3K4 trimethylation in germlines, there is scant evidence implicating epigenetic regulations in aging. The insulin/IGF-1 signaling (IIS) pathway is a major lifespan regulatory pathway. Here we show that progressive increases in gene expression and loss of H3K27me3 on IIS components are due, at least in part, to increased activity of the H3K27 demethylase UTX-1 during aging. RNAi of the utx-1 gene extended the mean lifespan of C. elegans by ~30%, dependent on DAF-16 activity and not additive in daf-2 mutants. The loss of utx-1 increased H3K27me3 on the Igf1r/daf-2 gene and decreased IIS activity leading to a more "naive" epigenetic state. Like stem cell reprogramming, our results suggest that reestablishing epigenetic marks lost during aging might help "reset" the developmental age of animal cells. Examination of H3K27me3 in young and old worms without or with Utx-1 RNAi.
Project description:How lifespan and the rate of aging are set is a key problem in biology. Small RNAs are conserved molecules that impact diverse biological processes through the control of gene expression. However, in contrast to miRNAs, the role of endo-siRNAs in aging remains unexplored. Here, by combining deep sequencing and genomic and genetic approaches in C.CaenorhabditisC. elegans elegans, we reveal an unprecedented role for endo-siRNA molecules in the maintenance of proteostasis and lifespan extension in germline-less animals. Furthermore, we identify an endo-siRNA-regulated tyrosine phosphatase, which limits the longevity of germline-less animals by restricting the activity of the heat shock transcription factor HSF-1. Altogether, our findings point to endo-siRNAs as a link between germline removal and the HSF-1 proteostasis and longevity-promoting somatic pathway. This establishes a role for endo siRNAs in the aging process and identifies downstream genes and physiological processes that are regulated by the endo siRNAs to affect longevity.
Project description:Epigenetic modifications are thought to be important for gene expression changes during development and aging. However, besides the Sir2 histone deacetylase in somatic tissues and H3K4 trimethylation in germlines, there is scant evidence implicating epigenetic regulations in aging. The insulin/IGF-1 signaling (IIS) pathway is a major lifespan regulatory pathway. Here we show that progressive increases in gene expression and loss of H3K27me3 on IIS components are due, at least in part, to increased activity of the H3K27 demethylase UTX-1 during aging. RNAi of the utx-1 gene extended the mean lifespan of C. elegans by ~30%, dependent on DAF-16 activity and not additive in daf-2 mutants. The loss of utx-1 increased H3K27me3 on the Igf1r/daf-2 gene and decreased IIS activity leading to a more "naive" epigenetic state. Like stem cell reprogramming, our results suggest that reestablishing epigenetic marks lost during aging might help "reset" the developmental age of animal cells.
Project description:we used Caenorhabditis elegans as a model organism, to investigate the effect of mannose on the lifespan. Using nematode RNAi methods, RT-PCR, RNA-seq and other experimental method, we explored the possible mechanism for how mannose change the lifespan of Caenorhabditis elegans.