Valproic acid extends Caenorhabditis elegans lifespan

Aging is an important biological phenomenon and a major contributor to human disease and disability, but no drugs have been demonstrated to delay human aging. Caenorhabditis elegans is a valuable model for studies of animal aging, and the analysis of drugs that extend the lifespan of this animal can elucidate mechanisms of aging and might lead to treatments for age-related disease. By testing drugs that are Food and Drug Administration approved for human use, we discovered that the mood stabilizer and anticonvulsant valproic acid (VA) extended C. elegans lifespan. VA also delayed age-related declines of body movement, indicating that VA delays aging. Valproic acid is a small carboxylic acid that is the most frequently prescribed anticonvulsant drug in humans. A structure-activity analysis demonstrated that the related compound valpromide also extends lifespan. Valproic acid treatment may modulate the insulin/IGF-1 growth factor signaling pathway, because VA promoted dauer larvae formation and DAF-16 nuclear localization. To investigate the mechanism of action of VA in delaying aging, we analyzed the effects of combining VA with other compounds that extend the lifespan of C. elegans. Combined treatment of animals with VA and the heterocyclic anticonvulsant trimethadione caused a lifespan extension that was significantly greater than treatment with either of these drugs alone. These data suggest that the mechanism of action of VA is distinct from that of trimethadione, and demonstrate that lifespan-extending drugs can be combined to produce additive effects.     

Dietary deprivation extends lifespan in Caenorhabditis elegans

Dietary restriction (DR) is well known as a nongenetic intervention that robustly extends lifespan in a variety of species; however, its underlying mechanisms remain unclear. We have found in Caenorhabditis elegans that dietary deprivation (DD) during adulthood, defined as removal of their food source Escherichia coli after the completion of larval development, increased lifespan and enhanced thermotolerance and resistance to oxidative stress. DD-induced longevity was independent of one C. elegans SIRTUIN, sir-2.1, which is required for the effects of DR, and was independent of the daf-2/insulin-like signaling pathway that independently regulates longevity and larval diapause in C. elegans. DD did not significantly alter lifespan of fem-1(hc17); eat-2(ad465) worms, a genetic model of DR. These findings suggest that DD and DR share some downstream effectors. In addition, DD was detrimental for longevity when imposed on reproductively active young adults, suggesting that DD may only be beneficial in the absence of competing metabolic demands, such as fertility. Adult-onset DD offers a new paradigm for investigating dietary regulation of longevity in C. elegans. This study presents the first evidence that long-term DD, instead of being detrimental, can extend lifespan of a multicellular adult organism.     

Lifespan extension in Caenorhabditis elegans by complete removal of food

A partial reduction in food intake has been found to increase lifespan in many different organisms. We report here a new dietary restriction regimen in the nematode Caenorhabditis elegans, based on the standard agar plate lifespan assay, in which adult worms are maintained in the absence of a bacterial food source. These findings represent the first report in any organism of lifespan extension in response to prolonged starvation. Removal of bacterial food increases lifespan to a greater extent than partial reduction of food through a mechanism that is distinct from insulin/IGF-like signaling and the Sir2-family deacetylase, SIR-2.1. Removal of bacterial food also increases lifespan when initiated in postreproductive adults, suggesting that dietary restriction started during middle age can result in a substantial longevity benefit that is independent of reproduction.     

Reduced expression of alpha-1,2-mannosidase I extends lifespan in Drosophila melanogaster and Caenorhabditis elegans

Exposure to sub-lethal levels of stress, or hormesis, was a means to induce longevity. By screening for mutations that enhance resistance to multiple stresses, we identified multiple alleles of alpha-1,2-mannosidase I ( mas1 ) which, in addition to promoting stress resistance, also extended longevity. Longevity enhancement is also observed when mas1 expression is reduced via RNA interference in both Drosophila melanogaster and Caenorhabditis elegans. The screen also identified Edem1 ( Edm1 ) , a gene downstream of mas1, as a modulator of lifespan. As double mutants for both mas1 and Edm1 showed no additional longevity enhancement, it appeared that both mutations function within a common pathway to extend lifespan. Molecular analysis of these mutants revealed that the expression of BiP , a putative biomarker of dietary restriction (DR), is down-regulated in response to reductions in mas1 expression. These findings suggested that mutations in mas1 may extend longevity by modulating DR.     

Inhibition of mRNA translation extends lifespan in Caenorhabditis elegans

Protein synthesis is a regulated cellular process that links nutrients in the environment to organismal growth and development. Here we examine the role of genes that regulate mRNA translation in determining growth, reproduction, stress resistance and lifespan. Translational control of protein synthesis by regulators such as the cap-binding complex and S6 kinase play an important role during growth. We observe that inhibition of various genes in the translation initiation complex including ifg-1, the worm homologue of eIF4G, which is a scaffold protein in the cap-binding complex; and rsks-1, the worm homologue of S6 kinase, results in lifespan extension in Caenorhabditis elegans. Inhibition of ifg-1 or rsks-1 also slows development, reduces fecundity and increases resistance to starvation. A reduction in ifg-1 expression in dauers was also observed, suggesting an inhibition of protein translation during the dauer state. Thus, mRNA translation exerts pleiotropic effects on growth, reproduction, stress resistance and lifespan in C. elegans.     

Two modes of mitochondrial dysfunction lead independently to lifespan extension in Caenorhabditis elegans

In Caenorhabditis elegans, longevity is increased by a partial loss‐of‐function mutation in the mitochondrial complex III subunit gene isp‐1. Longevity is also increased by RNAi against the expression of a variety of mitochondrial respiratory chain genes, including isp‐1, but it is unknown whether the isp‐1(qm150) mutation and the RNAi treatments trigger the same underlying mechanisms of longevity. We have identified nuo‐6(qm200), a mutation in a conserved subunit of mitochondrial complex I (NUDFB4). The mutation reduces the function of complex I and, like isp‐1(qm150), results in low oxygen consumption, slow growth, slow behavior, and increased lifespan. We have compared the phenotypes of nuo‐6(qm200) to those of nuo‐6(RNAi) and found them to be distinct in crucial ways, including patterns of growth and fertility, behavioral rates, oxygen consumption, ATP levels, autophagy, and resistance to paraquat, as well as expression of superoxide dismutases, mitochondrial heat‐shock proteins, and other gene expression markers. RNAi treatments appear to generate a stress and autophagy response, while the genomic mutation alters electron transport and reactive oxygen species metabolism. For many phenotypes, we also compared isp‐1(qm150) to isp‐1(RNAi) and found the same pattern of differences. Most importantly, we found that, while the lifespan of nuo‐6, isp‐1 double mutants is not greater than that of the single mutants, the lifespan increase induced by nuo‐6(RNAi) is fully additive to that induced by isp‐1(qm150), and the increase induced by isp‐1(RNAi) is fully additive to that induced by nuo‐6(qm200). Our results demonstrate that distinct and separable aspects of mitochondrial biology affect lifespan independently.     

Glyoxalase-1 prevents mitochondrial protein modification and enhances lifespan in Caenorhabditis elegans

Studies of mutations affecting lifespan in Caenorhabditis elegans show that mitochondrial generation of reactive oxygen species (ROS) plays a major causative role in organismal aging. Here, we describe a novel mechanism for regulating mitochondrial ROS production and lifespan in C .  elegans: progressive mitochondrial protein modification by the glycolysis-derived dicarbonyl metabolite methylglyoxal (MG). We demonstrate that the activity of glyoxalase-1, an enzyme detoxifying MG, is markedly reduced with age despite unchanged levels of glyoxalase-1 mRNA. The decrease in enzymatic activity promotes accumulation of MG-derived adducts and oxidative stress markers, which cause further inhibition of glyoxalase-1 expression. Over-expression of the C .  elegans glyoxalase-1 orthologue CeGly decreases MG modifications of mitochondrial proteins and mitochondrial ROS production, and prolongs C .  elegans lifespan. In contrast, knock-down of CeGly increases MG modifications of mitochondrial proteins and mitochondrial ROS production, and decreases C .  elegans lifespan.     

Pyruvate imbalance mediates metabolic reprogramming and mimics lifespan extension by dietary restriction in Caenorhabditis elegans

Dietary restriction (DR) is the most universal intervention known to extend animal lifespan. DR also prevents tumor development in mammals, and this effect requires the tumor suppressor PTEN. However, the metabolic and cellular processes that underly the beneficial effects of DR are poorly understood. We identified slcf‐1 in an RNAi screen for genes that extend Caenorhabditis elegans lifespan in a PTEN/daf‐18‐dependent manner. We showed that slcf‐1 mutation, which increases average lifespan by 40%, mimics DR in worms fed ad libitum. An NMR‐based metabolomic characterization of slcf‐1 mutants revealed lower lipid levels compared to wild‐type animals, as expected for dietary‐restricted animals, but also higher pyruvate content. Epistasis experiments and metabolic measurements support a model in which the long lifespan of slcf‐1 mutants relies on increased mitochondrial pyruvate metabolism coupled to an adaptive response to oxidative stress. This response requires DAF‐18/PTEN and the previously identified DR effectors PHA‐4/FOXA, HSF‐1/HSF1, SIR‐2.1/SIRT‐1, and AMPK/AAK‐2. Overall, our data show that pyruvate homeostasis plays a central role in lifespan control in C. elegans and that the beneficial effects of DR results from a hormetic mechanism involving the mitochondria. Analysis of the SLCF‐1 protein sequence predicts that slcf‐1 encodes a plasma membrane transporter belonging to the conserved monocarboxylate transporter family. These findings suggest that inhibition of this transporter homolog in mammals might also promote a DR response.     

秀丽隐杆线虫(Caenorhabditis elegans)在药物筛选中的应用

基于靶点的体外药物筛选操作相对简单,成本较低,但是由于药物在体内的作用并不仅仅取决于其与靶点的作用程度,吸收、分布、代谢、排泄特征和毒性均会对早期先导物能否进入临床使用产生极大的影响,因此,药物的体内筛选受到重视。本文重点综述了秀丽隐杆线虫（C.elegans）在抗衰老、抗感染药物筛选中的应用情况。秀丽隐杆线虫结构简单、易于培养和可实现高通量筛选,在未来的药物筛选中必将发挥更重要的作用。     

A steroid hormone that extends the lifespan of Caenorhabditis elegans

Removing the germline of Caenorhabditis elegans extends lifespan. This lifespan extension requires the nuclear receptor DAF-12 and the cytochrome P450 DAF-9, suggesting that a lipophilic hormone is involved. Here we show that C. elegans contains several hormonal steroids that are also present in humans, including pregnenolone (3beta-hydroxy-pregn-5-en-20-one; PREG) and other pregnane and androstane derivatives. We find that PREG can extend the lifespan of C. elegans. Moreover, PREG levels rise when the germline is removed in a daf-9-dependent fashion. PREG extends the lifespan of germline-defective daf-9 mutants dramatically, but has no effect on daf-12 mutants. Thus, germline removal may extend lifespan, at least in part, by stimulating the synthesis of PREG.     

Longevity determined by developmental arrest genes in Caenorhabditis elegans

The antagonistic pleiotropy theory of aging proposes that aging takes place because natural selection favors genes that confer benefit early on life at the cost of deterioration later in life. This theory predicts that genes that impact development would play a key role in shaping adult lifespan. To better understand the link between development and adult lifespan, we examined the genes previously known to be essential for development. From a pool of 57 genes that cause developmental arrest after inhibition using RNA interference, we have identified 24 genes that extend lifespan in Caenorhabditis elegans when inactivated during adulthood. Many of these genes are involved in regulation of mRNA translation and mitochondrial functions. Genetic epistasis experiments indicate that the mechanisms of lifespan extension by inactivating the identified genes may be different from those of the insulin/insulin-like growth factor 1 (IGF-1) and dietary restriction pathways. Inhibition of many of these genes also results in increased stress resistance and decreased fecundity, suggesting that they may mediate the trade-offs between somatic maintenance and reproduction. We have isolated novel lifespan-extension genes, which may help understand the intrinsic link between organism development and adult lifespan.     

Studies of Caenorhabditis elegans DAF-2/insulin signaling reveal targets for pharmacological manipulation of lifespan

Much excitement has arisen from the observation that decrements in insulin‐like signaling can dramatically extend lifespan in the nematode, Caenorhabditis elegans, and fruitfly, Drosophila melanogaster. In addition, there are tantalizing hints that the IGF‐I pathway in mice may have similar effects. In addition to dramatic effects on lifespan, invertebrate insulin‐like signaling also promotes changes in stress resistance, metabolism and development. Which, if any, of the various phenotypes of insulin pathway mutants are relevant to longevity? What are the genes that function in collaboration with insulin to prolong lifespan? These questions are at the heart of current research in C. elegans longevity. Two main theories exist as to the mechanism behind insulin's effects on invertebrate longevity. One theory is that insulin programs metabolic parameters that prolong or reduce lifespan. The other theory is that insulin determines the cell's ability to endure oxidative stress from respiration, thereby determining the rate of aging. However, these mechanisms are not mutually exclusive and several studies seem to support a role for both. Here, we review recently published reports investigating the mechanisms behind insulin's dramatic effect on longevity. We also spotlight several C. elegans genes that are now known to interact with insulin signaling to determine lifespan. These insights into pathways affecting invertebrate lifespan may provide a basis for developing strategies for pharmacological manipulation of human lifespan.     

C.elegans中dyn-1基因对寿命和发育的影响

细胞极性对于细胞的多样性起着很重要的作用。发动蛋白是一个大的GTP酶,作用于胞吞作用和肌动蛋白的动力学过程。C.elegans中发动蛋白的同源基因dyn-1起着维持早期细胞极性的功能。我们对C.elegans中dyn-1基因进行了克隆,并构建到表达载体和RNAi载体中。经IPTG诱导表达得到了约90 kDa的DYN-1融合蛋白。同时,利用RNAi方法研究了dyn-1基因沉默后对三种线虫虫株N2、daf-2（e1370）和daf-16（e1038）寿命的影响。C.elegans在喂食dyn-1 RNAi食物后寿命明显缩短,也会导致严重的不育和胚胎致死。     

Endocrine targets for pharmacological intervention in aging in Caenorhabditis elegans

Studies in the nematode Caenorhabditis elegans have been instrumental in defining genetic pathways that are involved in modulating lifespan. Multiple processes such as endocrine signaling, nutritional sensing and mitochondrial function play a role in determining lifespan in the worm and these mechanisms appear to be conserved across species. These discoveries have identified a range of novel targets for pharmacological manipulation of lifespan and it is likely that the nematode model will now prove useful in the discovery of compounds that slow aging. This review will focus on the endocrine targets for intervention in aging and the use of C. elegans as a system for high throughput screens of compounds for their effects on aging.     

A deuterohemin peptide extends lifespan and increases stress resistance in Caenorhabditis elegans

Abstract

This group has invented a novel deuterohemin containing peptide deuterohemin-AlaHisThrValGluLys (DhHP-6), which has various biological activities including protection of murine ischemia reperfusion injury, improving cell survival and preventing apoptosis. It was hypothesized that DhHP-6 is beneficial on the lifespan of Caenorhabditis elegans (C. elegans) and increases their resistance to heat and oxidative stress. C. elegans were treated with different concentrations of DhHP-6. Survival time and sensitivity to heat and paraquat were investigated. The data demonstrated that the mean survival time of C. elegans was significantly increased (p < 0.05) in the DhHP-6 treated group compared with the control group. The maximum lifespan was not affected by DhHP-6 treatment. DhHP-6 improved the survival rate of C. elegans in the acute heat stress (35°C) and rescued the C. elegans' sensitivity to paraquat in acute oxidative stress. Superoxide dismutase 3 (SOD-3) protein was up-regulated by DhHP-6 treatment. It was further demonstrated that stress resistance genes such as hsp-16.1, hsp-16.49 and sir-2.1 were regulated by DhHP-6. DAF-16 and SIR-2.1 genes are essential for the beneficial effect of DhHP-6. Therefore, the investigation into the beneficial effect of DhHP-6 on C. elegans' lifespan has the potential to develop novel drugs to prevent ageing.     

Counterbalance between BAG and URX neurons via guanylate cyclases controls lifespan homeostasis in C. elegans

Lifespan of C. elegans is affected by the nervous system; however, the underlying neural integration still remains unclear. In this work, we targeted an antagonistic neural system consisting of low‐oxygen sensing BAG neurons and high‐oxygen sensing URX neurons. While ablation of BAG neurons increases lifespan of C. elegans, ablation of URX neurons decreases lifespan. Genetic analysis revealed that BAG and URX neurons counterbalance each other via different guanylate cyclases (GCYs) to control lifespan balance. Lifespan‐modulating effects of GCYs in these neurons are independent of the actions from insulin/IGF‐1 signalling, germline signalling, sensory perception, or dietary restriction. Given the known gas‐sensing property of these neurons, we profiled that lifespan of C. elegans is promoted under moderately low oxygen (4–12%) or moderately high carbon dioxide (5%) but inhibited under high‐level oxygen (40%); however, these pro‐longevity and anti‐longevity effects are counteracted, respectively, by BAG and URX neurons via different GCYs. In conclusion, BAG and URX neurons work as a neural‐regulatory system to counterbalance each other via different GCYs to control lifespan homeostasis.     

Glucose-induced abnormal egg-laying rate in Caenorhabditis elegans

High glucose reduced the egg-laying rate of the nematode Caenorhabditis elegans and was dependent on serotonergic signaling. Antidiabetic drugs of the biguanide and thiazolidine classes ameliorated the detrimental effect of glucose on egg-laying rate, suggesting the possibility that this quick and easy assay system may be applicable to whole-animal screening for novel antidiabetic drugs, at least, of these classes.