Lifespan In Drosophila Research Articles

Heat shock factor 1 mediates the longevity conferred by inhibition of TOR and insulin/IGF‐1 signaling pathways in C. elegans

Target of rapamycin (TOR) signaling is an evolutionarily well-conserved pathway that regulates various physiologic processes, including aging and metabolism. One of the key downstream components of TOR signaling is ribosomal protein S6 kinase (S6K) whose inhibition extends the lifespan of yeast, Caenorhabditis elegans, Drosophila, and mice. Here, we demonstrate that the activation of heat shock factor 1 (HSF-1), a crucial longevity transcription factor known to act downstream of the insulin/IGF-1 signaling (IIS) pathway, mediates the prolonged lifespan conferred by mutations in C.elegans S6K (rsks-1). We found that hsf-1 is required for the longevity caused by down-regulation of components in TOR signaling pathways, including TOR and S6K. The induction of a small heat-shock protein hsp-16, a transcriptional target of HSF-1, mediates the long lifespan of rsks-1 mutants. Moreover, we show that synergistic activation of HSF-1 is required for the further enhanced longevity caused by simultaneous down-regulation of TOR and IIS pathways. Our findings suggest that HSF-1 acts as an essential longevity factor that intersects both IIS and TOR signaling pathways.

External control of the Drosophila melanogaster lifespan by combination of 3D oscillating low-frequency electric and magnetic fields

We demonstrate that the lifespan of Drosophila melanogaster population is controllable by a combination of external three-dimensional oscillating low-frequency electric and magnetic fields (3D OLFEMFs). The lifespan was decreased or increased in dependence of the parameters of the external 3D OLFEMFs. We propose that metabolic processes in D. melanogaster’s body are either accelerated (in the case of reduced lifespan) or slowed down (in the case of increased lifespan) in function of 3D OLFEMFs that induce vibrational motions on sub-cellular and larger scales.

Improved functional abilities of the life-extended Drosophila mutant Methuselah are reversed at old age to below control levels.

Methuselah (mth) is a chromosome 3 Drosophila mutant with an increased lifespan. A large number of studies have investigated the genetic, molecular, and biochemical mechanisms of the mth gene. Much less is known about the effects of mth on preservation of sensorimotor abilities throughout Drosophila's lifespan, particularly in late life. The current study investigated functional senescence in mth and its parental-control line (w1118) in two experiments that measured age-dependent changes in flight functions and locomotor activity. In experiment 1, a total of 158 flies (81 mth and 77 controls) with an age range from 10 to 70days were individually tethered under an infrared laser-sensor system that allowed monitoring of flight duration during phototaxic flight. We found that mth has a statistically significant advantage in maintaining continuous flight over control flies at age 10days, but not during middle and late life. At age 70days, the trend reversed and parental control flies had a small but significant advantage, suggesting an interaction between age and genotype in the ability to sustain flight. In experiment 2, a total of 173 different flies (97 mth and 76 controls) with an age range from 50 to 76days were individually placed in a large well-lit arena (60 × 45cm) and their locomotor activity quantified as the distance walked in a 1-min period. Results showed that mth flies had lower levels of locomotor activity relative to controls at ages 50 and 60days. These levels converged for the two genotypes at the oldest ages tested. Findings show markedly different patterns of functional decline for the mth line relative to those previously reported for other life-extended genotypes, suggesting that different life-extending genes have dissimilar effects on preservation of sensory and motor abilities throughout an organism's lifespan.

Juvenile hormone regulation of Drosophila aging

BackgroundJuvenile hormone (JH) has been demonstrated to control adult lifespan in a number of non-model insects where surgical removal of the corpora allata eliminates the hormone’s source. In contrast, little is known about how juvenile hormone affects adult Drosophila melanogaster. Previous work suggests that insulin signaling may modulate Drosophila aging in part through its impact on juvenile hormone titer, but no data yet address whether reduction of juvenile hormone is sufficient to control Drosophila life span. Here we adapt a genetic approach to knock out the corpora allata in adult Drosophila melanogaster and characterize adult life history phenotypes produced by reduction of juvenile hormone. With this system we test potential explanations for how juvenile hormone modulates aging.ResultsA tissue specific driver inducing an inhibitor of a protein phosphatase was used to ablate the corpora allata while permitting normal development of adult flies. Corpora allata knockout adults had greatly reduced fecundity, inhibited oogenesis, impaired adult fat body development and extended lifespan. Treating these adults with the juvenile hormone analog methoprene restored all traits toward wildtype. Knockout females remained relatively long-lived even when crossed into a genotype that blocked all egg production. Dietary restriction further extended the lifespan of knockout females. In an analysis of expression profiles of knockout females in fertile and sterile backgrounds, about 100 genes changed in response to loss of juvenile hormone independent of reproductive state.ConclusionsReduced juvenile hormone alone is sufficient to extend the lifespan of Drosophila melanogaster. Reduced juvenile hormone limits reproduction by inhibiting the production of yolked eggs, and this may arise because juvenile hormone is required for the post-eclosion development of the vitellogenin-producing adult fat body. Our data do not support a mechanism for juvenile hormone control of longevity simply based on reducing the physiological costs of egg production. Nor does the longevity benefit appear to function through mechanisms by which dietary restriction extends longevity. We identify transcripts that change in response to juvenile hormone independent of reproductive state and suggest these represent somatically expressed genes that could modulate how juvenile hormone controls persistence and longevity.

Extension of Drosophila Lifespan by Rhodiola rosea through a Mechanism Independent from Dietary Restriction

Rhodiola rosea has been extensively used to improve physical and mental performance and to protect against stress. We, and others, have reported that R. rosea can extend lifespan in flies, worms, and yeast. However, its molecular mechanism is currently unknown. Here, we tested whether R. rosea might act through a pathway related to dietary restriction (DR) that can extend lifespan in a range of model organisms. While the mechanism of DR itself is also unknown, three molecular pathways have been associated with it: the silent information regulator 2 (SIR2) proteins, insulin and insulin-like growth factor signaling (IIS), and the target of rapamycin (TOR). In flies, DR is implemented through a reduction in dietary yeast content. We found that R. rosea extract extended lifespan in both sexes independent of the yeast content in the diet. We also found that the extract extended lifespan when the SIR2, IIS, or TOR pathways were genetically perturbed. Upon examination of water and fat content, we found that R. rosea decreased water content and elevated fat content in both sexes, but did not sensitize flies to desiccation or protect them against starvation. There were some sex-specific differences in response to R. rosea. In female flies, the expression levels of glycolytic genes and dSir2 were down-regulated, and NADH levels were decreased. In males however, R. rosea provided no protection against heat stress and had no effect on the major heat shock protein HSP70 and actually down-regulated the mitochondrial HSP22. Our findings largely rule out an elevated general resistance to stress and DR-related pathways as mechanistic candidates. The latter conclusion is especially relevant given the limited potential for DR to improve human health and lifespan, and presents R. rosea as a potential viable candidate to treat aging and age-related diseases in humans.

Overexpression of Sir2 in the adult fat body is sufficient to extend lifespan of male and female Drosophila

Sir2 is the most intensively discussed longevity gene in current aging research. Although, the gene encoding a NAD(+)-dependent histone deacetylase initially was found to extend lifespan of various organisms ranging from yeast to mammals, serious doubts regarding its role in longevity have been expressed recently. In this study, we tested whether tissue-specific overexpression of Sir2 in the adult fat body can extend lifespan when compared to genetically identical controls. We also wanted to elucidate the mechanisms by which fat body Sir2 promotes longevity by studying the phenotypic and transcriptional changes in the fat body. We found that moderate (3-fold) Sir2 overexpression in the fat body during adulthood only can promote longevity in both sexes by roughly 13 %. In addition, we obtained transcriptional profiles elicited by this overexpression and propose a role for Sir2 in lipid droplet biology especially under conditions of starvation. Furthermore, our data do not support the idea of Sir2 mediating the response to dietary restriction (DR) because transcriptional profiles of fat bodies after DR or Sir2 overexpression do not match. This study provides additional independent evidence for the concept of Sir2 as a longevity gene and as a promising pharmacological target to cure age-related diseases.

Influence on Longevity of Blueberry, Cinnamon, Green and Black Tea, Pomegranate, Sesame, Curcumin, Morin, Pycnogenol, Quercetin, and Taxifolin Fed Iso-Calorically to Long-Lived, F1 Hybrid Mice

Phytonutrients reportedly extend the life span of Caenorhabditis elegans, Drosophila, and mice. We tested extracts of blueberry, pomegranate, green and black tea, cinnamon, sesame, and French maritime pine bark (Pycnogenol and taxifolin), as well as curcumin, morin, and quercetin for their effects on the life span of mice. While many of these phytonutrients reportedly extend the life span of model organisms, we found no significant effect on the life span of male F1 hybrid mice, even though the dosages used reportedly produce defined therapeutic end points in mice. The compounds were fed beginning at 12 months of age. The control and treatment groups were iso-caloric with respect to one another. A 40% calorically restricted and other groups not reported here did experience life span extension. Body weights were un-changed relative to controls for all but two supplemented groups, indicating most supplements did not change energy absorption or utilization. Tea extracts with morin decreased weight, whereas quercetin, taxifolin, and Pycnogenol together increased weight. These changes may be due to altered locomotion or fatty acid biosynthesis. Published reports of murine life span extension using curcumin or tea components may have resulted from induced caloric restriction. Together, our results do not support the idea that isolated phytonutrient anti-oxidants and anti-inflammatories are potential longevity therapeutics, even though consumption of whole fruits and vegetables is associated with enhanced health span and life span.

β1-Adrenergic receptor blockade extends the life span of Drosophila and long-lived mice

Chronic treatment with β-adrenergic receptor (βAR) agonists increases mortality and morbidity while βAR antagonists (β-blockers) decrease all-cause mortality for those at risk of cardiac disease. Levels of sympathetic nervous system βAR agonists and βAR activity increase with age, and this increase may hasten the development of age-related mortality. Here, we show that β-blockers extend the life span of healthy metazoans. The β-blockers metoprolol and nebivolol, administered in food daily beginning at 12 months of age, significantly increase the mean and median life span of isocalorically fed, male C3B6F1 mice, by 10 and 6.4%, respectively (P < 0.05). Neither drug affected the weight or food intake of the mice, indicating that induced CR is not responsible for these effects, and that energy absorption and utilization are not altered by the drugs. Both β-blockers were investigated to control for their idiosyncratic, off-target effects. Metoprolol and nebivolol extended Drosophila life span, without affecting food intake or locomotion. Thus, βAR antagonists are capable of directly extending the life span of two widely divergent metazoans, suggesting that these effects are phylogenetically highly conserved. Thus, long-term use of β-blockers, which are generally well-tolerated, may enhance the longevity of healthy humans.

Curcumin and aging

Turmeric has been used commonly as a spice, food additive, and an herbal medicine worldwide. Known as a bioactive polyphenolic extract of Turmeric, curcumin has a broad range of health benefit properties for humans. Recently, active research on curcumin with respect to aging and related traits in model organisms has demonstrated that curcumin and its metabolite, tetrahydrocurcumin (THC), increase mean lifespan of at least three model organisms: nematode roundworm, fruit fly Drosophila, and mouse. Nematodes grown on media containing curcumin showed a significantly increased lifespan by reducing the production of reactive oxygen species. Genes osr-1, sek-1, mek-1, skn-1, unc-43, sir-2.1, and age-1 are required for curcumin-mediated lifespan extension. The lifespan extension of Drosophila by curcumin supplementation was associated with increased superoxide dismutase (SOD) activity, and decreased lipofuscin and malondialdehyde levels. Curcumin up-regulated expression of SOD genes and down-regulated expression of several age-related genes, such as dInR, ATTD, Def, CecB, and DptB. In addition, THC extended lifespan in Drosophila and inhibited the oxidative stress response by regulating FOXO and Sir2. Mice fed diets containing THC starting at the age of 13 months had significantly increased mean lifespan. In summary, the positive effects of curcumin on lifespan extension likely arise from beneficial regulation of common oxidative stress responses and age-related genes. Understanding the molecular mechanism(s) of curcumin action has provided base knowledge and rationale for future human clinical trials, and for nutritional intervention in aging and age-associated disorders in humans.

Genomic response to selection for postponed senescence in Drosophila

Limited lifespan and senescence are quantitative traits, controlled by many interacting genes with individually small and environmentally plastic effects, complicating genetic analysis. We performed genome wide analysis of gene expression for two Drosophila melanogaster lines selected for postponed senescence and one control, unselected line to identify candidate genes affecting lifespan as well as variation in lifespan. We obtained gene expression profiles for young flies of all lines, all lines at the time only 10% of the control lines survived, and the time at which 10% of the selected lines survived. Transcriptional responses to aging involved 19% of the genome. The transcriptional signature of aging involved the down-regulation of genes affecting proteolysis, metabolism, oxidative phosphorylation, and mitochrondrial function; and the up-regulation of genes affecting protein synthesis, immunity, defense responses, and the detoxification of xenobiotic substances. The transcriptional signature of postponed senescence involved the up-regulation of proteases and phosphatases and genes affecting detoxification of xenobiotics; and the down-regulation of genes affecting immunity, defense responses, metabolism and muscle function. Functional tests of 17 mutations confirmed 12 novel genes affecting Drosophila lifespan. Identification of genes affecting longevity by analysis of gene expression changes in lines selected for postponed senescence thus complements alternative genetic approaches.

Effects of overexpression of mitochondrial transcription factor A on lifespan and oxidative stress response in Drosophila melanogaster

Mitochondrial transcription factor A (TFAM) plays a role in the maintenance of mitochondrial DNA (mtDNA) by packaging mtDNA, forming the mitochondrial nucleoid. There have been many reports about a function of TFAM at the cellular level, but only a few studies have been done in individual organisms. Here we examined the effects of TFAM on the Drosophila lifespan and oxidative stress response, by overexpressing TFAM using the GAL4/UAS system. Under standard conditions, the lifespan of TFAM-overexpressing flies was shorter than that of the control flies. However, the lifespan of TFAM-overexpressing flies was longer when they were treated with 1% H2O2. These results suggest that even though excess TFAM has a negative influence on lifespan, it has a defensive function under strong oxidative stress. In the TFAM-overexpressing flies, no significant changes in mtDNA copy number or mtDNA transcription were observed. However, the results of a total antioxidant activity assay suggest the possibility that TFAM is involved in the elimination of oxidative stress. The present results clearly show the effects of TFAM overexpression on the lifespan of Drosophila under both standard conditions and oxidative stress conditions, and our findings contribute to the understanding of the physiological mechanisms involving TFAM in mitochondria.

Reproducible effects of the mitochondria-targeted plastoquinone derivative SkQ1 on Drosophila melanogaster lifespan under different experimental scenarios

Previously, extremely low, nanomolar concentrations of the mitochondria-targeted plastoquinone derivative SkQ1 (10-(6'-plastoquinonyl) decyltriphenylphosphonium) were shown to prolong the lifespan of male and female Drosophila melanogaster by about 10 % (Anisimov et al., Biochemistry (Moscow) 73:1329-1342, 2008). Using long-term monitoring of SkQ1 effects on the Drosophila lifespan, we analyzed different integral parameters of Drosophila survival and mortality under SkQ1 treatment. Meta-analysis was used to evaluate the average SkQ1 effect measured in terms of standard deviation. The effect appeared to be 0.25 for females and 0.18 for males, which corresponds to a low effect by Cohen's "Rules-of-Thumb". The SkQ1 effects on the Drosophila lifespan were reproducible over six years and showed no relationship to fluctuations in the mean lifespan of the w(1118) line used in the experiments, methods of preparation and administration of the drug, seasons, or calendar years. Adding SkQ1 to fly food was associated with a reduction in early mortality and a decrease in random variation in lifespan. All survival curves were fitted by Gompertz function. Analysis of the Gompertz function parametric plane demonstrated significant differences between points corresponding to experimental and control cohorts. The Strehler-Mildvan correlations for 11 experiments with females and for 7 experiments with males were calculated. The significant increase in the slope of the regression lines indicated that feeding flies SkQ1 reduced the rate of fall of fly vitality and, consequently, slowed aging. These findings indicated that the SkQ1 effect on lifespan was associated with both elevation of life quality and slowing of aging.

Activation of AMPK by the Putative Dietary Restriction Mimetic Metformin Is Insufficient to Extend Lifespan in Drosophila

The biguanide drug, metformin, commonly used to treat type-2 diabetes, has been shown to extend lifespan and reduce fecundity in C. elegans through a dietary restriction-like mechanism via the AMP-activated protein kinase (AMPK) and the AMPK-activating kinase, LKB1. We have investigated whether the longevity-promoting effects of metformin are evolutionarily conserved using the fruit fly, Drosophila melanogaster. We show here that while feeding metformin to adult Drosophila resulted in a robust activation of AMPK and reduced lipid stores, it did not increase lifespan in either male or female flies. In fact, we found that when administered at high concentrations, metformin is toxic to flies. Furthermore, no decreases in female fecundity were observed except at the most toxic dose. Analysis of intestinal physiology after metformin treatment suggests that these deleterious effects may result from disruptions to intestinal fluid homeostasis. Thus, metformin appears to have evolutionarily conserved effects on metabolism but not on fecundity or lifespan.

Dietary phosphate modifies lifespan in Drosophila

Phosphate is required for many important cellular processes and having too little phosphate (hypophosphatemia) or too much (hyperphosphatemia) can cause disease and reduce lifespan in humans. Drosophila melanogaster has been a powerful tool to discover evolutionarily well-conserved nutrient-sensing pathways that are important for the lifespan extension. We have established Drosophila as a model system for studying the effects of dietary phosphate during development and adult life. When absorption of phosphate is blocked by sevelamer or cellular uptake is inhibited by phosphonoformic acid (PFA), larval development is delayed in a phosphate-dependent fashion. Conversely, restriction of phosphate absorption with sevelamer or reduced cellular uptake after treatment with PFA is able to extend the adult lifespan of otherwise normal flies. Gaining an understanding of the specific pathways and mediators that regulate cellular and organismic phosphate levels might ultimately lead to the development of improved dietary and therapeutic approaches to the treatment of human disorders of hypo- and hyperphosphatemia.

Heat Shock and Caloric Restriction Have a Synergistic Effect on the Heat Shock Response in a sir2.1-dependent Manner in Caenorhabditis elegans

The heat shock response (HSR) is responsible for maintaining cellular and organismal health through the regulation of proteostasis. Recent data demonstrating that the mammalian HSR is regulated by SIRT1 suggest that this response may be under metabolic control. To test this hypothesis, we have determined the effect of caloric restriction in Caenorhabditis elegans on activation of the HSR and have found a synergistic effect on the induction of hsp70 gene expression. The homolog of mammalian SIRT1 in C. elegans is Sir2.1. Using a mutated C. elegans strain with a sir2.1 deletion, we show that heat shock and caloric restriction cooperate to promote increased survivability and fitness in a sir2.1-dependent manner. Finally, we show that caloric restriction increases the ability of heat shock to preserve movement in a polyglutamine toxicity neurodegenerative disease model and that this effect is dependent on sir2.1.

Pharmacological modulation of histone demethylase activity by a small molecule isolated from subcritical water extracts of Sasa senanensis leaves prolongs the lifespan of Drosophila melanogaster

BackgroundExtracts of Sasa senanensis Rehder are used in traditional Japanese medicine; however, little is known about the underlying mechanisms of their potential health benefits.MethodsS. senanensis leaves were extracted with subcritical water. An active small-molecule was isolated using reversed-phase high-performance liquid chromatography (HPLC), and identified as 3,4-dihydroxybenzaldehyde (protocatechuic aldehyde or PA). The effects of PA on the activity of histone demethylase, the Drosophila melanogaster lifespan and gene expression in Drosophila S2 cells were investigated.ResultsPA inhibited the activity of Jumonji domain-containing protein 2A (JMJD2A) histone demethylase in a dose-dependent manner with a half-maximal inhibitory concentration (IC50) of 11.6 μM. However, there was no effect on lysine-specific demethylase 1 (LSD1), histone deacetylase 1 (HDAC1) or HDAC8. PA significantly extended the lifespan of female, but not male, Drosophila. In Drosophila S2 cells, the eukaryotic translation initiation factor 4E binding protein (4E-BP) was up-regulated by PA exposure.ConclusionsOur findings provide insight into the possible relationship between the pharmacological modulation of histone demethylation and lifespan extension by PA; they might also be important in the development of alternative therapies for age-related disorders.

Curcumin-supplemented diets increase superoxide dismutase activity and mean lifespan in Drosophila

Curcumin is a polyphenolic bioactive compound in turmeric. We examined if antioxidant effects of curcumin are associated with lifespan extension in Drosophila. In this experiment, females and males of Drosophila were fed diets either containing no curcumin (C0) or supplemented with curcumin at 0.5 (C1) and 1.0 (C2) mg/g of diet. The levels of malondialdehyde (MDA), enzyme activity of superoxide dismutase (SOD), and expression of seven age-related genes in females and males were analyzed. We found that C1 and C2 increased mean lifespan by 6.2 % and 25.8 % in females, and by 15.5 % and 12.6 % in males, respectively. Meanwhile, C1 and C2 significantly decreased MDA levels and increased SOD activity in both genders. Diets C1 in females and C2 in males are effective in extending mean lifespan and improving levels of two physiological and biochemical measures related to aging in Drosophila. Lifespan extension of curcumin in Drosophila was associated with the up-regulation of Mn-SOD and CuZn-SOD genes, and the down-regulation of dInR, ATTD, Def, CecB, and DptB genes. The present results suggest that curcumin increases mean lifespan of Drosophila via regulating gene expression of the key enzyme SOD and reducing accumulation of MDA and lipid peroxidation. This study provided new insights for understanding the anti-aging mechanism of curcumin in Drosophila.

Age-dependent changes in the transcription profile of long-lived Drosophila over-expressing glutamate cysteine ligase

In our prior studies (Orr et al., 2005) we achieved a 30–50% increase in the life span of Drosophila by manipulating glutathione (GSH) production in neuronal tissues, through over-expression of glutamate-cysteine ligase (GCL), a key enzyme in glutathione biosynthesis. In the present study, we identified gene response patterns from which plausible mechanisms responsible for the observed effects on life span might be inferred. Functional clustering analysis of the transcriptome data revealed that biological processes affected by GCLc in young flies (10days) were generally related to cell morphogenesis and differentiation, while those in older flies were associated with nucleosome organization and detoxification processes. Notably, in older flies there was considerable reduction in the expression of genes related to humoral immunity in the GCLc over-expressors and this was observed in flies of the same chronological age (∼40days old flies) and in flies of equivalent physiological age (10% dead for both experimentals and controls). Our study demonstrates that most of the GSH-mediated processes and targets are relatively distinct in young and old flies. Nevertheless there exists a restricted number of related processes affected by GCLc in both young and old flies and prominent among them are those associated with proteolysis and metabolism.

Induced toxicity with intake chronic zearalenone on the life span of adult drosophila

Damage-associated molecular patterns (DAMPs), so-called “danger signals,” play important roles in host defense and pathophysiology in mammals and insects. In Drosophila, the Toll pathway confers damage responses during bacterial infection and improper cell-fate control. However, the intrinsic ligands and signaling mechanisms that potentiate innate immune responses remain unknown. Here, we demonstrate that a Drosophila larva-derived tissue extract strongly elicits Toll pathway activation via the Toll receptor. Using this extract, we performed ex vivo genome-wide RNAi screening in Drosophila cultured cells, and identified several signaling factors that are required for host defense and antimicrobial-peptide expression in Drosophila adults. These results suggest that our larva-derived tissue extract contains active ingredients that mediate Toll pathway activation, and the screening data will shed light on the mechanisms of damage-related Toll pathway signaling in Drosophila.

Midlife gene expressions identify modulators of aging through dietary interventions

Dietary interventions are effective ways to extend or shorten lifespan. By examining midlife hepatic gene expressions in mice under different dietary conditions, which resulted in different lifespans and aging-related phenotypes, we were able to identify genes and pathways that modulate the aging process. We found that pathways transcriptionally correlated with diet-modulated lifespan and physiological changes were enriched for lifespan-modifying genes. Intriguingly, mitochondrial gene expression correlated with lifespan and anticorrelated with aging-related pathological changes, whereas peroxisomal gene expression showed an opposite trend. Both organelles produce reactive oxygen species, a proposed causative factor of aging. This finding implicates a contribution of peroxisome to aging. Consistent with this hypothesis, lowering the expression levels of peroxisome proliferation genes decreased the cellular peroxide levels and extended the lifespan of Drosophila melanogaster and Caenorhabditis elegans. These findings show that transcriptional changes resulting from dietary interventions can effectively reflect causal factors in aging and identify previously unknown or under-appreciated longevity pathways, such as the peroxisome pathway.