Project description:Dietary restriction (DR) has been shown to increase lifespan in organisms ranging from yeast to mammals. This suggests that the underlying mechanisms may be evolutionarily conserved. Indeed, upstream signalling pathways, such as TOR, are strongly linked to DR-induced longevity in various organisms. However, the downstream effector proteins that ultimately mediate lifespan extension are less clear. To shed light on this, we used a proteomic approach on budding yeast. Our reasoning was that analysis of proteome-wide changes in response to DR might enable the identification of proteins that mediate its physiological effects, including lifespan extension. Of over 2500 proteins we identified by liquid chromatography-mass spectrometry, 183 were significantly altered in expression by at least 3-fold in response to DR. Most of these proteins were mitochondrial and/or had clear links to respiration and metabolism. Indeed, direct analysis of oxygen consumption confirmed that mitochondrial respiration was increased several-fold in response to DR. In addition, several key proteins involved in mating, including Ste2 and Ste6, were downregulated by DR. Consistent with this, shmoo formation in response to α-factor pheromone was reduced by DR, thus confirming the inhibitory effect of DR on yeast mating. Finally, we found that Hsp26, a member of the conserved small heat shock protein (sHSP) family, was upregulated by DR and that overexpression of Hsp26 extends yeast replicative lifespan. As overexpression of sHSPs in C. elegans and Drosophila has previously been shown to extend lifespan, our data on yeast Hsp26 suggest that sHSPs may be universally conserved effectors of longevity.
Project description:The SIRT1 deacetylase is one of the best-studied potential mediators of some of the anti-aging effects of calorie restriction (CR); but its role in CR-dependent lifespan extension has not been demonstrated. We previously found that mice lacking both copies of SIRT1 displayed a shorter median lifespan than wild type mice on an ad libitum diet. Here we report that median lifespan extension in CR heterozygote SIRT1+/- mice was identical (51%) to that observed in wild type mice but SIRT1+/- mice displayed a higher frequency of some certain pathologies. Although larger studies in different genetic backgrounds are necessary , these results provide strong initial evidence for the requirement of SIRT1 for the anti-aging effects of CR, but suggest that its high expression is not required for CR-induced lifespan extension. Key words: SIRT1, caloric restriction, lifespan, anti-aging 2-5 month old male mice of 3 different genotypes (SIRT1+/+, SIRT1+/-, and SIRT1-/-) that had normal, reduced or no expression of SIRT1 were treated with either a 40% caloric restricted diet (CR) or an ad libitum diet (AL). 2-4 replicates of each experimental condition were used in the analysis.
Project description:The SIRT1 deacetylase is one of the best-studied potential mediators of some of the anti-aging effects of calorie restriction (CR); but its role in CR-dependent lifespan extension has not been demonstrated. We previously found that mice lacking both copies of SIRT1 displayed a shorter median lifespan than wild type mice on an ad libitum diet. Here we report that median lifespan extension in CR heterozygote SIRT1+/- mice was identical (51%) to that observed in wild type mice but SIRT1+/- mice displayed a higher frequency of some certain pathologies. Although larger studies in different genetic backgrounds are necessary , these results provide strong initial evidence for the requirement of SIRT1 for the anti-aging effects of CR, but suggest that its high expression is not required for CR-induced lifespan extension. Key words: SIRT1, caloric restriction, lifespan, anti-aging
Project description:DNA repair-deficient Ercc1Δ/- mice show premature cell death, senescence and numerous accelerated aging features limiting lifespan to 4-6 month. Simultaneously they exhibit a ‘survival response’, which suppresses growth and enhances maintenance, resembling the anti-aging response induced by dietary restriction (DR). Here we report that subjecting these progeroid, dwarf mutants to actual dietary restriction (DR) resulted in the largest lifespan increase recorded in mammals. Thirty percent DR tripled median and maximal remaining lifespan, and drastically retarded numerous aspects of accelerated aging, e.g. DR animals retained 50% more neurons and maintained full motoric function. The DR response in Ercc1Δ/- mice resembled DR in wild type animals including reduced insulin signaling. Interestingly, ad libitum Ercc1Δ/- liver expression profiles showed preferential extinction of expression of long genes, consistent with genome-wide accumulation of stochastic, transcription-blocking lesions, which affect long genes more than short ones. DR largely prevented this decline of transcriptional output, indicating that DR prolongs genome function. Our findings strengthen the link between DNA damage and aging, establish Ercc1Δ/- mice as powerful model for identifying interventions to promote healthy aging, reveal untapped potential for reducing endogenous damage, provide new venues for understanding the molecular mechanism of DR, and suggest a counterintuitive DR-like therapy for human progeroid genome instability syndromes and DR-like interventions for preventing neurodegenerative diseases.
Project description:DNA repair-deficient Ercc1Δ/- mice show premature cell death, senescence and numerous accelerated aging features limiting lifespan to 4-6 month. Simultaneously they exhibit a ‘survival response’, which suppresses growth and enhances maintenance, resembling the anti-aging response induced by dietary restriction (DR). Here we report that subjecting these progeroid, dwarf mutants to actual dietary restriction (DR) resulted in the largest lifespan increase recorded in mammals. Thirty percent DR tripled median and maximal remaining lifespan, and drastically retarded numerous aspects of accelerated aging, e.g. DR animals retained 50% more neurons and maintained full motoric function. The DR response in Ercc1Δ/- mice resembled DR in wild type animals including reduced insulin signaling. Interestingly, ad libitum Ercc1Δ/- liver expression profiles showed preferential extinction of expression of long genes, consistent with genome-wide accumulation of stochastic, transcription-blocking lesions, which affect long genes more than short ones. DR largely prevented this decline of transcriptional output, indicating that DR prolongs genome function. Our findings strengthen the link between DNA damage and aging, establish Ercc1Δ/- mice as powerful model for identifying interventions to promote healthy aging, reveal untapped potential for reducing endogenous damage, provide new venues for understanding the molecular mechanism of DR, and suggest a counterintuitive DR-like therapy for human progeroid genome instability syndromes and DR-like interventions for preventing neurodegenerative diseases.
Project description:Hormesis occurs when a low level stress elicits adaptive beneficial responses that protect against subsequent exposure to severe stress. Recent findings suggest that mild oxidative and thermal stress can extend lifespan by hormetic mechanisms. Here we show that the botanical pesticide plumbagin, while toxic to C. elegans nematodes at high doses, extends lifespan at low doses. Because plumbagin is a naphthoquinone that generates free radicals in vivo, we investigated whether it extends lifespan by activating an adaptive cellular stress response pathway. Mammalian NF-E2-related factor 2 (Nrf2) and its C. elegans ortholog SKN-1, mediate protective responses to oxidative stress by promoting target gene expression via antioxidant response elements (ARE). Genetic analyses showed that skn-1 mediates plumbagin’s lifespan-extending effect in C. elegans. Further screening of a series of plumbagin analogs identified three additional naphthoquinones that could induce SKN-1 targets in C. elegans. Naphthazarin showed skn-1-dependent lifespan extension, over an extended dose range compared to plumbagin, while the other naphthoquinones, oxoline and menadione, had differing effects on C. elegans survival and failed to activate ARE reporter expression in cultured mammalian cells. Our findings reveal the potential for low doses of naturally occurring naphthoquinones to extend lifespan by engaging a specific adaptive cellular stress response pathway.