Lifespan In Drosophila Research Articles

Metabolic Signatures of Life Span Regulated by Mating, Sex Peptide, and Mifepristone/RU486 in Female Drosophila melanogaster.

Mating and transfer of male sex peptide (SP), or transgenic expression of SP, causes inflammation and decreased life span in female Drosophila. Mifepristone rescues these effects, yielding dramatic increases in life span. Here targeted metabolomics data were integrated with further analysis of extant transcriptomic data. Each of 7 genes positively correlated with life span were expressed in the brain or eye and involved regulation of gene expression and signaling. Genes negatively correlated with life span were preferentially expressed in midgut and involved protein degradation, amino acid metabolism, and immune response. Across all conditions, life span was positively correlated with muscle breakdown product 1/3-methylhistidine and purine breakdown product urate, and negatively correlated with tryptophan breakdown product kynurenic acid, suggesting a SP-induced shift from somatic maintenance/turnover pathways to the costly production of energy and lipids from dietary amino acids. Some limited overlap was observed between genes regulated by mifepristone and genes known to be regulated by ecdysone; however, mifepristone was unable to compete with ecdysone for activation of an ecdysone-responsive transgenic reporter. In contrast, genes regulated by mifepristone were highly enriched for genes regulated by juvenile hormone (JH), and mifepristone rescued the negative effect of JH analog methoprene on life span in adult virgin females. The data indicate that mifepristone increases life span and decreases inflammation in mated females by antagonizing JH signaling downstream of male SP. Finally, mifepristone increased life span of mated, but not unmated, Caenorhabditis elegans, in 2 of 3 trials, suggesting possible evolutionary conservation of mifepristone mechanisms.

Lipoic acid rejuvenates aged intestinal stem cells by preventing age‐associated endosome reduction

The age‐associated decline of adult stem cell function is closely related to the decline in tissue function and age‐related diseases. However, the underlying mechanisms that ultimately lead to the observed functional decline of stem cells still remain largely unexplored. This study investigated Drosophila midguts and found a continuous downregulation of lipoic acid synthase, which encodes the key enzyme for the endogenous synthesis of alpha‐lipoic acid (ALA), upon aging. Importantly, orally administration of ALA significantly reversed the age‐associated hyperproliferation of intestinal stem cells (ISCs) and the observed decline of intestinal function, thus extending the lifespan of Drosophila. This study reports that ALA reverses age‐associated ISC dysfunction by promoting the activation of the endocytosis–autophagy network, which decreases in aged ISCs. Moreover, this study suggests that ALA may be used as a safe and effective anti‐aging compound for the treatment of ISC‐dysfunction‐related diseases and for the promotion of healthy aging in humans.

Lifespan regulation in α/β posterior neurons of the fly mushroom bodies by Rab27.

Brain function has been implicated to control the aging process and modulate lifespan. However, continuous efforts remain for the identification of the minimal sufficient brain region and the underlying mechanism for neuronal regulation of longevity. Here, we show that the Drosophila lifespan is modulated by rab27 functioning in a small subset of neurons of the mushroom bodies (MB), a brain structure that shares analogous functions with mammalian hippocampus and hypothalamus. Depleting rab27 in the α/βp neurons of the MB is sufficient to extend lifespan, enhance systemic stress responses, and alter energy homeostasis, all without trade‐offs in major life functions. Within the α/βp neurons, rab27KO causes the mislocalization of phosphorylated S6K thus attenuates TOR signaling, resulting in decreased protein synthesis and reduced neuronal activity. Consistently, expression of dominant‐negative S6K in the α/βp neurons increases lifespan. Furthermore, the expression of phospho‐mimetic S6 in α/βp neurons of rab27KO rescued local protein synthesis and reversed lifespan extension. These findings demonstrate that inhibiting TOR‐mediated protein synthesis in α/βp neurons is sufficient to promote longevity.

An Insulin-Sensitive Circular RNA that Regulates Lifespan in Drosophila

SummaryCircular RNAs (circRNAs) are abundant and accumulate with age in neurons of diverse species. However, only few circRNAs have been functionally characterized, and their role during aging has not been addressed. Here, we use transcriptome profiling during aging and find that accumulation of circRNAs is slowed down in long-lived insulin mutant flies. Next, we characterize the in vivo function of a circRNA generated by the sulfateless gene (circSfl), which is consistently upregulated, particularly in the brain and muscle, of diverse long-lived insulin mutants. Strikingly, lifespan extension of insulin mutants is dependent on circSfl, and overexpression of circSfl alone is sufficient to extend the lifespan. Moreover, circSfl is translated into a protein that shares the N terminus and potentially some functions with the full-length Sfl protein encoded by the host gene. Our study demonstrates that insulin signaling affects global circRNA accumulation and reveals an important role of circSfl during aging in vivo.

Ganoderma lucidum spore oil (GLSO), a novel antioxidant, extends the average life span in Drosophila melanogaster

In ancient China, Ganoderma lucidum was believed to be a medical fungus that could increase lifespan. Recently, pharmacologic studies have found that polysaccharide peptides and triterpenoids extracted from Ganoderma lucidum have various physiological effects as active compounds. However, the effects of spore oil isolated from Ganoderma lucidum remains unknown. In this study, the biological effects of Ganoderma lucidum spore oil (GLSO) were evaluated using a Drosophila melanogaster model. Compared with untreated groups, groups treated with GLSO had significantly longer average and maximum lifespan in both normal conditions and under oxidative stress. The activities of various antioxidant enzymes were measured to determine the antioxidant effect of GLSO. GLSO treatment markedly enhanced total superoxide dismutase (SOD) and catalase (CAT) activity and decreased levels of malondialdehyde (MDA). Further, we found dose-dependent increases in the mRNA expression of Cu, Zn-SOD, Mn-SOD, and CAT in GLSO-treated groups. These results suggest that GLSO may effectively eliminate free radicals and extend lifespan in Drosophila. Future work should investigate the value of GLSO as a functional food for the prevention of aging in larger animal models.

Dcf1 alleviates C99-mediated deficits in drosophila by reducing the cleavage of C99

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder. The generation of amyloid-β from the amyloid precursor protein (APP) C-terminal fragment (C99) by γ-secretase cleavage is one of the main pathological mechanisms of AD. Dendritic cell factor 1 (Dcf1) is a membrane protein that was previously found to play a role in the development of AD. Bioinformatic analysis of AD patients indicated that Dcf1 may affect γ-secretase. In this study, we confirmed that Dcf1 attenuates the cleavage of C99 in vivo and in vitro. By using C99 transgenic AD drosophila, we found that Dcf1 reduces the cleavage of C99 by γ-secretase using Dcf1 overexpression. The climbing ability and lifespan of C99 drosophila were significantly increased, while learning and memory were also enhanced with Dcf1 expression. Increased levels of C99 protein in Dcf1-AD drosophila reveals inhibition of C99 cleavage by Dcf1 in vivo. Dcf1 inhibition of γ-secretase was further confirmed in vitro. These results provide a potential therapeutic target for the treatment of AD and also propose a new mechanism for understanding the occurrence of AD.

Tau Accumulation via Reduced Autophagy Mediates GGGGCC Repeat Expansion-Induced Neurodegeneration in Drosophila Model of ALS.

Expansions of trinucleotide or hexanucleotide repeats lead to several neurodegenerative disorders, including Huntington disease [caused by expanded CAG repeats (CAGr) in the HTT gene], and amyotrophic lateral sclerosis [ALS, possibly caused by expanded GGGGCC repeats (G4C2r) in the C9ORF72 gene], of which the molecular mechanisms remain unclear. Here, we demonstrated that lowering the Drosophila homologue of tau protein (dtau) significantly rescued in vivo neurodegeneration, motor performance impairments, and the shortened life-span in Drosophila expressing expanded CAGr or expanded G4C2r. Expression of human tau (htau4R) restored the disease-related phenotypes that had been mitigated by the loss of dtau, suggesting an evolutionarily-conserved role of tau in neurodegeneration. We further revealed that G4C2r expression increased tau accumulation by inhibiting autophagosome-lysosome fusion, possibly due to lowering the level of BAG3, a regulator of autophagy and tau. Taken together, our results reveal a novel mechanism by which expanded G4C2r causes neurodegeneration via an evolutionarily-conserved mechanism. Our findings provide novel autophagy-related mechanistic insights into C9ORF72-ALS and possible entry points to disease treatment.

Mating status affects Drosophila lifespan, metabolism and antioxidant system

In Drosophila melanogaster, lifespan and fitness traits were investigated as a function of mating status. Four mating protocols were used: virgin males and females, males and females allowed to copulate only once; males and females that had multiple copulations with one partner over the 5-day mating period; and polygamous males and females that had multiple copulations with different partners over the 5-day mating period. Virgin females had the longest lifespan, and polygamous females had the shortest lifespan, potentially due to injuries, infections or exposure to toxic accessory gland products obtained from different males. Reduced lifespan was also observed in males mated to multiple females. Unexpectedly, mating decreased the amount of food eaten by flies. Mating to different partners decreased the amount of fat in both sexes. The number of eggs laid and their quality was increased in females mated to multiple males. Mating status influenced superoxide dismutase (SOD) and peroxidase (PX) activities, as well as the content of advanced glycation end products (AGEs). The mRNA levels of the insulin receptor (InR) gene were significantly increased in the polygamously mated female group compared to the virgin group. Levels of dTOR mRNA were lower in polygamous females. These results indicate that insulin/IGF-1 signaling (IIS) and Drosophila target of rapamycin (dTOR) pathways can mediate the link between mating status and longevity in Drosophila.

Antioxidant and anti-aging activities of polysaccharides from Cordyceps cicadae

Cordyceps cicadae is a traditional Chinese medicine with high nutritional value and biological activities. Previously, we reported on the antioxidant activity associated with the polysaccharides from Cordyceps cicadae (CP). To further explore which of the fraction of CP had the greatest potency, in here, the in vitro antioxidant and in vivo anti-aging activities of the fractions CP30–CP80 of CP were evaluated. The in vitro antioxidant activity results revealed that all the fractions (i.e. CP30–CP80) were potent with CP70 as the most potent. Notably, CP70 prolonged the lifespan of Drosophila (P < 0.05), increased the activities of catalase (CAT) and glutathione peroxidase (GSH-Px) (P < 0.01), and inhibited the formation of malondialdehyde (MDA) (P < 0.01). Additionally, CP70 upregulated the expression level of antioxidant-related genes CAT, SOD1 and MTH in Drosophila (P < 0.05). These results indicated that CP70 may prolong the lifespan of Drosophila through the up-regulation of the expression level of antioxidant-related genes CAT, SOD1 and MTH in Drosophila. Thus, polysaccharides from Cordyceps cicadae possess significant antioxidant and anti-aging activities, and could be explored as a new dietary supplement to slow down the aging process.

The neuronal receptor tyrosine kinase Alk is a target for longevity.

Inhibition of signalling through several receptor tyrosine kinases (RTKs), including the insulin‐like growth factor receptor and its orthologues, extends healthy lifespan in organisms from diverse evolutionary taxa. This raises the possibility that other RTKs, including those already well studied for their roles in cancer and developmental biology, could be promising targets for extending healthy lifespan. Here, we focus on anaplastic lymphoma kinase (Alk), an RTK with established roles in nervous system development and in multiple cancers, but whose effects on aging remain unclear. We find that several means of reducing Alk signalling, including mutation of its ligand jelly belly (jeb), RNAi knock‐down of Alk, or expression of dominant‐negative Alk in adult neurons, can extend healthy lifespan in female, but not male, Drosophila. Moreover, reduced Alk signalling preserves neuromuscular function with age, promotes resistance to starvation and xenobiotic stress, and improves night sleep consolidation. We find further that inhibition of Alk signalling in adult neurons modulates the expression of several insulin‐like peptides, providing a potential mechanistic link between neuronal Alk signalling and organism‐wide insulin‐like signalling. Finally, we show that TAE‐684, a small molecule inhibitor of Alk, can extend healthy lifespan in Drosophila, suggesting that the repurposing of Alk inhibitors may be a promising direction for strategies to promote healthy aging.

A widespread family of heat-resistant obscure (Hero) proteins protect against protein instability and aggregation.

Proteins are typically denatured and aggregated by heating at near-boiling temperature. Exceptions to this principle include highly disordered and heat-resistant proteins found in extremophiles, which help these organisms tolerate extreme conditions such as drying, freezing, and high salinity. In contrast, the functions of heat-soluble proteins in non-extremophilic organisms including humans remain largely unexplored. Here, we report that heat-resistant obscure (Hero) proteins, which remain soluble after boiling at 95°C, are widespread in Drosophila and humans. Hero proteins are hydrophilic and highly charged, and function to stabilize various "client" proteins, protecting them from denaturation even under stress conditions such as heat shock, desiccation, and exposure to organic solvents. Hero proteins can also block several different types of pathological protein aggregations in cells and in Drosophila strains that model neurodegenerative diseases. Moreover, Hero proteins can extend life span of Drosophila. Our study reveals that organisms naturally use Hero proteins as molecular shields to stabilize protein functions, highlighting their biotechnological and therapeutic potential.

Jouvence a small nucleolar RNA required in the gut extends lifespan in Drosophila

Longevity is influenced by genetic and environmental factors, but the underlying mechanisms remain elusive. Here, we functionally characterise a Drosophila small nucleolar RNA (snoRNA), named jouvence whose loss of function reduces lifespan. The genomic region of jouvence rescues the longevity in mutant, while its overexpression in wild-type increases lifespan. Jouvence is required in enterocytes. In mutant, the epithelium of the gut presents more hyperplasia, while the overexpression of jouvence prevents it. Molecularly, the mutant lack pseudouridylation on 18S and 28S-rRNA, a function rescued by targeted expression of jouvence in the gut. A transcriptomic analysis performed from the gut reveals that several genes are either up- or down-regulated, while restoring the mRNA level of two genes (ninaD or CG6296) rescue the longevity. Since snoRNAs are structurally and functionally well conserved throughout evolution, we identified putative jouvence orthologue in mammals including humans, suggesting that its function in longevity could be conserved.

Bioactive peptides derived from crimson snapper and in vivo anti-aging effects on fat diet-induced high fat Drosophila melanogaster.

Crimson snapper is an important marine economy fish, and its scales are rich in collagen. Crimson snapper scale peptides (CSSPs) obtained from crimson snapper scales by enzymatic hydrolysis exhibited significantly antioxidant activities to DPPH, ABTS and hydroxyl radicals in vitro. In vivo antioxidant and anti-aging effects of CSSPs on the Drosophila melanogaster aging model constructed by lard were investigated in this study. The results showed that CSSPs could prolong the mean lifespan, 50% survival days and the maximum lifespan of Drosophila, and especially when the concentration of CSSPs was increased to 6 mg mL-1, the mean lifespan of male and female Drosophila increased by 21.2% and 26.2%, respectively, indicating the effective life extension effect of CSSPs. Meanwhile, the addition of CSSPs effectively reduced the contents of malondialdehyde (MDA) and protein carbonylation (PCO) and increased the levels of total superoxide dismutase (T-SOD) and catalase (CAT) in Drosophila, which showed a significant dose dependence. Besides, the antioxidant-related genes SOD1, SOD2 and CAT were up-regulated in Drosophila when fed with diets containing CSSPs. In conclusion, CSSPs played an antioxidant and anti-aging role by reducing the accumulation of peroxide products and improving the activity of antioxidant enzymes, as well as by up-regulating the expression of antioxidant-related genes. The results suggest that CSSPs have potential to be used in the food and healthcare industries as potential food-borne antioxidant and anti-aging agents.

Early-life hypoxia alters adult physiology and reduces stress resistance and lifespan in Drosophila.

In many animals, short-term fluctuations in environmental conditions in early life often exert long-term effects on adult physiology. In Drosophila, one ecologically relevant environmental variable is hypoxia. Drosophila larvae live on rotting, fermenting food rich in microorganisms, an environment characterized by low ambient oxygen. They have therefore evolved to tolerate hypoxia. Although the acute effects of hypoxia in larvae have been well studied, whether early-life hypoxia affects adult physiology and fitness is less clear. Here, we show that Drosophila exposed to hypoxia during their larval period subsequently show reduced starvation stress resistance and shorter lifespan as adults, with these effects being stronger in males. We find that these effects are associated with reduced whole-body insulin signaling but elevated TOR kinase activity, a manipulation known to reduce lifespan. We also identify a sexually dimorphic effect of larval hypoxia on adult nutrient storage and mobilization. Thus, we find that males, but not females, show elevated levels of lipids and glycogen. Moreover, we see that both males and females exposed to hypoxia as larvae show defective lipid mobilization upon starvation stress as adults. These data demonstrate how early-life hypoxia can exert persistent, sexually dimorphic, long-term effects on Drosophila adult physiology and lifespan.

Investigating Alcohol Behavior and Physiology Using Drosophila melanogaster.

Drosophila melanogaster, the fruit fly, is one of the most versatile models for biomedical studies due to the economical husbandry, rapid generation time, and the array of tools for spatial and temporal gene manipulation. The relatively short lifespan of Drosophila (60-80days) and the high degree of molecular conservation across species make Drosophila ideal to study the complexities of aging. Alcohol is the most abused drug worldwide and alcohol use disorders represent a significant public health problem and economic burden to individuals and society. Stereotypical alcohol-induced behaviors and the underlying molecular mechanisms are conserved from flies to humans making Drosophila a practical model for investigating the development of alcohol-induced behaviors and alcohol pathologies. Here, we outline how to assemble an efficient and controlled alcohol vapor delivery system, the FlyBar, and review paradigms and protocols for the assessment of alcohol-induced behaviors and physiology in Drosophila including the loss-of-righting reflex, sedation, tolerance, alcohol metabolism, and gut permeability.

Analysis of Drosophila melanogaster Lifespan.

The laboratory fruit fly Drosophila melanogaster is one of the leading models for the study of aging. Whereas several behavioral and physiological biomarkers of aging have been identified for Drosophila, lifespan remains the most robust measure of aging rate. Aging and lifespan can be modulated by genetic alterations, as well as by drugs and dietary components, to reveal basic and conserved mechanisms of aging. Here methods are presented for Drosophila lifespan assay, including media preparation, supplementation of media with various drugs, culturing of the flies, passaging flies and recording deaths, and the analysis of lifespan data.

Parental dietary protein-to-carbohydrate ratio affects offspring lifespan and metabolism in drosophila

Non-genetic inheritance of metabolic state over multiple generations has been widely reported in insects. The present study uses the fruit fly, Drosophila melanogaster, to assess whether lifespan, physiological traits and metabolism are affected by the dietary protein-to-carbohydrate ratio (P:C) of the prior adult generation. Groups of parental flies were fed diets with different P:C ratios. Their progeny groups were raised on the same diet so the only variable in the experiments was the diet fed to the parents. Parental P:C affected the lifespan of female offspring, however had no impact on F1 males survival. Low parental P:C increased feeding rate in progeny. An increase in the P:C ratio from 0.03 to 0.65 decreased the levels of body glucose and trehalose in the offspring and a similar tendency was observed in the levels of circulating hemolymph glucose and trehalose. Offspring also accumulated less triglycerides but more glycogen when parents were fed a low P:C diet. Our study indicates that the parental dietary P:C ration has a strong impact on the lifespan, reproduction, appetite and metabolism in the offspring generation.

Longevity in response to lowered insulin signaling requires glycine N-methyltransferase-dependent spermidine production.

Reduced insulin/IGF signaling (IIS) extends lifespan in multiple organisms. Different processes in different tissues mediate this lifespan extension, with a set of interplays that remain unclear. We here show that, in Drosophila, reduced IIS activity modulates methionine metabolism, through tissue‐specific regulation of glycine N‐methyltransferase (Gnmt), and that this regulation is required for full IIS‐mediated longevity. Furthermore, fat body‐specific expression of Gnmt was sufficient to extend lifespan. Targeted metabolomics showed that reducing IIS activity led to a Gnmt‐dependent increase in spermidine levels. We also show that both spermidine treatment and reduced IIS activity are sufficient to extend the lifespan of Drosophila, but only in the presence of Gnmt. This extension of lifespan was associated with increased levels of autophagy. Finally, we found that increased expression of Gnmt occurs in the liver of liver‐specific IRS1 KO mice and is thus an evolutionarily conserved response to reduced IIS. The discovery of Gnmt and spermidine as tissue‐specific modulators of IIS‐mediated longevity may aid in developing future therapeutic treatments to ameliorate aging and prevent disease.

DOES AUGMENTATION OF MITOCHONDRIAL THIOREDOXIN REDUCTASE 2 IMPROVE METABOLIC FITNESS?

Mitochondrial Thioredoxin Reductase (TrxR2) is a rate limiting enzyme in the mitochondrial thioredoxin system which serves as one of the major mitochondrial ROS scavenging pathways. Txnrd2 is also a repressor of the ASK-1 oxidative stress induced apoptotic pathway. Our group previously identified a correlation with the expression of this protein and long-lived species and its overexpression prolonged lifespan in Drosophila. We have generated a TrxR2 transgenic (T-tg) mouse which has ubiquitously heighted (two-fold) TrxR2 expression. We found that overexpression of TrxR2 leads to enhanced mitochondrial metabolism and increased resistance to mitochondrial oxidative damage in MEFs (data not shown). We also found that female T-tg mice showed a leaner trend and reduced food consumption, with improved glucose tolerance but no difference in insulin sensitivity. These mice showed a lower Oxygen consumption and CO2 production with lower energy expenditure in individual metabolic cages. We further tested their exercise capacity where T-tg mice had a similar performance to control mice. These results suggest that TrxR2 overexpression can lead to some beneficial metabolic changes that need to be further understood. (Acknowledgments to Nathan Shock Lifespan assessment Core for the help developing all these assays in mice).

Extension of Drosophila lifespan by Korean red ginseng through a mechanism dependent on dSir2 and insulin/IGF-1 signaling.

Many studies have indicated that Korean red ginseng (KRG) has anti-inflammatory and anti-oxidative effects, thereby inducing many health benefits in humans. Studies into the longevity effects of KRG are limited and have provided contradictory results, and the molecular mechanism of lifespan extension by KRG is not elucidated yet. Herein, the longevity effect of KRG was investigated in Drosophila melanogaster by feeding KRG extracts, and the molecular mechanism of lifespan extension was elucidated by using longevity-related mutant flies. KRG extended the lifespan of Drosophila when administrated at 10 and 25 μg/mL, and the longevity benefit of KRG was not due to reduced feeding, reproduction, and/or climbing ability in fruit flies, indicating that the longevity benefit of KRG is a direct effect of KRG, not of a secondary artifact. Diet supplementation with KRG increased the lifespan of flies on a full-fed diet but not of those on a restricted diet, and the longevity effect of KRG was diminished by the mutation of dSir2, a deacetylase known to mediate the benefits of dietary restriction. Similarly, the longevity effect of KRG was mediated by the reduction of insulin/IGF-1 signaling. In conclusion, KRG extends the lifespan of Drosophila through Sir2 and insulin/IGF-1 signaling and has potential as an anti-aging dietary-restriction mimetic and prolongevity supplement.