The amyloid precursor protein intracellular domain induces sleep disruptions and its nuclear localization fluctuates in circadian pacemaker neurons in Drosophila and mice.

The most prominent symptom of Alzheimer's disease (AD) is cognitive decline; however, sleep and other circadian disruptions are also common in AD patients. Sleep disruptions have been connected with memory problems and therefore the changes in sleep patterns observed in AD patients may also actively contribute to cognitive decline. However, the underlying molecular mechanisms that connect sleep disruptions and AD are unclear. A characteristic feature of AD is the formation of plaques consisting of Amyloid-ß (Aß) peptides generated by cleavage of the Amyloid Precursor Protein (APP). Besides Aß, APP cleavage generates several other fragments, including the APP intracellular domain (AICD) that has been linked to transcriptional regulation and neuronal homeostasis. Here we show that overexpression of the AICD reduces the early evening expression of two core clock genes and disrupts the sleep pattern in flies. Analyzing the subcellular localization of the AICD in pacemaker neurons, we found that the AICD levels in the nucleus are low during daytime but increase at night. While this pattern of nuclear AICD persisted with age, the nighttime levels were higher in aged flies. Increasing the cleavage of the fly APP protein also disrupted AICD nuclear localization. Lastly, we show that the day/nighttime nuclear pattern of the AICD is also detectable in neurons in the suprachiasmatic nucleus of mice and that it also changes with age. Together, these data suggest that AD-associated changes in APP processing and the subsequent changes in AICD levels may cause sleep disruptions in AD.

FTD-associated mutations in Tau result in a combination of dominant and recessive phenotypes.

Although mutations in the microtubules-associated protein Tau have long been connected with several neurodegenerative diseases, the underlying molecular mechanisms causing these tauopathies are still not fully understood. Studies in various models suggested that dominant gain-of-function effects underlie the pathogenicity of these mutants; however, there is also evidence that the loss of normal physiological functions of Tau plays a role in tauopathies. Previous studies on Tau in Drosophila involved expressing the human Tau protein in the background of the endogenous Tau gene in addition to inducing high expression levels. To study Tau pathology in more physiological conditions, we recently created Drosophila knock-in models that express either wildtype human Tau (hTauWT) or disease-associated mutant hTau (hTauV337M and hTauK369I) in place of the endogenous Drosophila Tau (dTau). Analyzing these flies as homozygotes, we could therefore detect recessive effects of the mutations while identifying dominant effects in heterozygotes. Using memory, locomotion and sleep assays, we found that homozygous mutant hTau flies showed deficits already when quite young whereas in heterozygous flies, disease phenotypes developed with aging. Homozygotes also revealed an increase in microtubule diameter, suggesting that changes in the cytoskeleton underlie the axonal degeneration we observed in these flies. In contrast, heterozygous mutant hTau flies showed abnormal axonal targeting and no detectable changes in microtubules. However, we previously showed that heterozygosity for hTauV337M interfered with synaptic homeostasis in central pacemaker neurons and we now show that heterozygous hTauK369I flies have decreased levels of proteins involved in the release of synaptic vesicles. Taken together, our results demonstrate that both mutations induce a combination of dominant and recessive disease-related phenotypes that provide behavioral and molecular insights into the etiology of Tauopathies.

ER responses play a key role in Swiss-Cheese/Neuropathy Target Esterase-associated neurodegeneration.

Swiss Cheese (SWS) is the Drosophila orthologue of Neuropathy Target Esterase (NTE), a phospholipase that when mutated has been shown to cause a spectrum of disorders in humans that range from intellectual disabilities to ataxia. Loss of SWS in Drosophila also causes locomotion deficits, age-dependent neurodegeneration, and an increase in lysophosphatidylcholine (LPC) and phosphatidylcholine (PC). SWS is localized to the Endoplasmic Reticulum (ER), and recently, it has been shown that perturbing the membrane lipid composition of the ER can lead to the activation of ER stress responses through the inhibition of the Sarco/Endoplasmic Reticulum Ca2+ ATPase (SERCA). To investigate whether ER stress induction occurs in NTE-associated disorders, we used the fly sws null mutant as a model. sws flies showed an activated ER stress response as determined by elevated levels of the chaperone GRP78 and by increased splicing of XBP, an ER transcription factor that activates transcriptional ER stress responses. To address whether ER stress plays a role in the degenerative and behavioral phenotypes detected in sws1, we overexpressed XBP1, or treated the flies with tauroursodeoxycholic acid (TUDCA), a chemical known to attenuate ER stress-mediated cell death. Both manipulations suppressed the locomotor deficits and neurodegeneration of sws1. In addition, sws1 flies showed reduced SERCA levels and expressing additional SERCA also suppressed the sws1-related phenotypes. This suggests that the disruption in lipid compositions and its effect on SERCA are inducing ER stress, aimed to ameliorate the deleterious effects of sws1. This includes the effects on lipid composition because XBP1 and SERCA expression also reduced the LPC levels in sws1. Promoting cytoprotective ER stress pathways may therefore provide a therapeutic approach to alleviate the neurodegeneration and motor symptoms seen in NTE-associated disorders.

Reduced Expression of Foxp1 as a Contributing Factor in Huntington's Disease.

Huntington's disease (HD) is an inherited neurodegenerative disease caused by a polyglutamine expansion in the huntington protein (htt). The neuropathological hallmark of HD is the loss of neurons in the striatum and, to a lesser extent, in the cortex. Foxp1 is a member of the Forkhead family of transcription factors expressed selectively in the striatum and the cortex. In the brain, three major Foxp1 isoforms are expressed: isoform-A (∼90 kDa), isoform-D (∼70 kDa), and isoform-C (∼50 kDa). We find that expression of Foxp1 isoform-A and -D is selectively reduced in the striatum and cortex of R6/2 HD mice as well as in the striatum of HD patients. Furthermore, expression of mutant htt in neurons results in the downregulation of Foxp1 Elevating expression of isoform-A or -D protects cortical neurons from death caused by the expression of mutant htt On the other hand, knockdown of Foxp1 promotes death in otherwise healthy neurons. Neuroprotection by Foxp1 is likely to be mediated by the transcriptional stimulation of the cell-cycle inhibitory protein p21Waf1/Cip1 Consistently, Foxp1 activates transcription of the p21Waf1/Cip1 gene promoter, and overexpression of Foxp1 in neurons results in the elevation of p21 expression. Moreover, knocking down of p21Waf1/Cip1 blocks the ability of Foxp1 to protect neurons from mut-Htt-induced neurotoxicity. We propose that the selective vulnerability of neurons of the striatum and cortex in HD is related to the loss of expression of Foxp1, a protein that is highly expressed in these neurons and required for their survival.SIGNIFICANCE STATEMENT Although the mutant huntingtin gene is expressed widely, neurons of the striatum and cortex are selectively affected in Huntington's disease (HD). Our results suggest that this selectivity is attributable to the reduced expression of Foxp1, a protein expressed selectively in striatal and cortical neurons that plays a neuroprotective role in these cells. We show that protection by Foxp1 involves stimulation of the p21Waf1/Cip1 (Cdkn1a) gene. Although three major Foxp1 isoforms (A, C, and D) are expressed in the brain, only isoform-A has been studied in the nervous system. We show that isoform-D is also expressed selectively, neuroprotective and downregulated in HD mice and patients. Our results suggest that Foxp1 might be an attractive therapeutic target for HD.

NTE/PNPLA6 is expressed in mature Schwann cells and is required for glial ensheathment of Remak fibers.

Neuropathy target esterase (NTE) or patatin-like phospholipase domain containing 6 (PNPLA6) was first linked with a neuropathy occurring after organophosphate poisoning and was later also found to cause complex syndromes when mutated, which can include mental retardation, spastic paraplegia, ataxia, and blindness. NTE/PNPLA6 is widely expressed in neurons but experiments with its Drosophila orthologue Swiss-cheese (SWS) suggested that it may also have glial functions. Investigating whether NTE/PNPLA6 is expressed in glia, we found that NTE/PNPLA6 is expressed by Schwann cells in the sciatic nerve of adult mice with the most prominent expression in nonmyelinating Schwann cells. Within Schwann cells, NTE/PNPLA6 is enriched at the Schmidt-Lanterman incisures and around the nucleus. When analyzing postnatal expression patterns, we did not detect NTE/PNPLA6 in promyelinating Schwann cells, while weak expression was detectable at postnatal day 5 in Schwann cells and increased with their maturation. Interestingly, NTE/PNPLA6 levels were upregulated after nerve crush and localized to ovoids forming along the nerve fibers. Using a GFAP-based knock-out of NTE/PNPLA6, we detected an incomplete ensheathment of Remak fibers whereas myelination did not appear to be affected. These results suggest that NTE/PNPLA6 is involved in the maturation of nonmyelinating Schwann cells during development and de-/remyelination after neuronal injury. Since Schwann cells play an important role in maintaining axonal viability and function, it is therefore likely that changes in Schwann cells contribute to the locomotory deficits and neuropathy observed in patients carrying mutations in NTE.

The genetic basis of cerebral palsy.

Although prematurity and hypoxic-ischaemic injury are well-recognized contributors to the pathogenesis of cerebral palsy (CP), as many as one-third of children with CP may lack traditional risk factors. For many of these children, a genetic basis to their condition is suspected. Recent findings have implicated copy number variants and mutations in single genes in children with CP. Current studies are limited by relatively small patient numbers, the underlying genetic heterogeneity identified, and the paucity of validation studies that have been performed. However, several genes mapping to intersecting pathways controlling neurodevelopment and neuronal connectivity have been identified. Analogous to other neurodevelopmental disorders such as autism and intellectual disability, the genomic architecture of CP is likely to be highly complex. Although we are just beginning to understand genetic contributions to CP, new insights are anticipated to serve as a unique window into the neurobiology of CP and suggest new targets for intervention.

Manipulations of amyloid precursor protein cleavage disrupt the circadian clock in aging Drosophila.

Alzheimer's disease (AD) is a neurodegenerative disease characterized by severe cognitive deterioration. While causes of AD pathology are debated, a large body of evidence suggests that increased cleavage of Amyloid Precursor Protein (APP) producing the neurotoxic Amyloid-ß (Aß) peptide plays a fundamental role in AD pathogenesis. One of the detrimental behavioral symptoms commonly associated with AD is the fragmentation of sleep-activity cycles with increased nighttime activity and daytime naps in humans. Sleep-activity cycles, as well as physiological and cellular rhythms, which may be important for neuronal homeostasis, are generated by a molecular system known as the circadian clock. Links between AD and the circadian system are increasingly evident but not well understood. Here we examined whether genetic manipulations of APP-like (APPL) protein cleavage in Drosophila melanogaster affect rest-activity rhythms and core circadian clock function in this model organism. We show that the increased ß-cleavage of endogenous APPL by the ß-secretase (dBACE) severely disrupts circadian behavior and leads to reduced expression of clock protein PER in central clock neurons of aging flies. Our data suggest that behavioral rhythm disruption is not a product of APPL-derived Aß production but rather may be caused by a mechanism common to both α and ß-cleavage pathways. Specifically, we show that increased production of the endogenous Drosophila Amyloid Intracellular Domain (dAICD) caused disruption of circadian rest-activity rhythms, while flies overexpressing endogenous APPL maintained stronger circadian rhythms during aging. In summary, our study offers a novel entry point toward understanding the mechanism of circadian rhythm disruption in Alzheimer's disease.

Mutations in γ adducin are associated with inherited cerebral palsy.

OBJECTIVE: Cerebral palsy is estimated to affect nearly 1 in 500 children, and although prenatal and perinatal contributors have been well characterized, at least 20% of cases are believed to be inherited. Previous studies have identified mutations in the actin-capping protein KANK1 and the adaptor protein-4 complex in forms of inherited cerebral palsy, suggesting a role for components of the dynamic cytoskeleton in the genesis of the disease. METHODS: We studied a multiplex consanguineous Jordanian family by homozygosity mapping and exome sequencing, then used patient-derived fibroblasts to examine functional consequences of the mutation we identified in vitro. We subsequently studied the effects of adducin loss of function in Drosophila. RESULTS: We identified a homozygous c.1100G>A (p.G367D) mutation in ADD3, encoding gamma adducin in all affected members of the index family. Follow-up experiments in patient fibroblasts found that the p.G367D mutation, which occurs within the putative oligomerization critical region, impairs the ability of gamma adducin to associate with the alpha subunit. This mutation impairs the normal actin-capping function of adducin, leading to both abnormal proliferation and migration in cultured patient fibroblasts. Loss of function studies of the Drosophila adducin ortholog hts confirmed a critical role for adducin in locomotion. INTERPRETATION: Although likely a rare cause of cerebral palsy, our findings indicate a critical role for adducins in regulating the activity of the actin cytoskeleton, suggesting that impaired adducin function may lead to neuromotor impairment and further implicating abnormalities of the dynamic cytoskeleton as a pathogenic mechanism contributing to cerebral palsy.

Drosophila GGA model: an ultimate gateway to GGA analysis.

Golgi-localized, γ-ear-containing, ADP ribosylation factor-binding (GGA) proteins are monomeric adaptors implicated in clathrin-mediated vesicular transport between the trans Golgi network and endosomes, characterized mainly from cell culture analysis of lysosomal sorting. To provide the first demonstration of GGA's role in vivo, we used Drosophila which has a single GGA and a single lysosomal sorting receptor, lysosomal enzyme receptor protein (LERP). Using RNAi knockdowns, we show that the Drosophila GGA is required for lysosomal sorting. We further identified authentic components of the Drosophila lysosomal sorting system--the sorting receptor LERP, the sorting adaptor GGA and the lysosomal cargo cathepsins B1, D and L--to show that GGA depletion results in lysosomal dysfunction. Abnormal lysosomal morphology, missorting of lysosomal cathepsins and impaired lysosomal proteolysis show disturbed LERP trafficking after GGA depletion. GGA is highly expressed in the mushroom bodies and the pigment cells of the retina, and increasing or decreasing the levels of GGA in the eyes leads to retinal defects. Reduced GGA levels also enhance an eye defect caused by overexpression of the autophagy-associated protein Blue cheese (Bchs), implicating GGA in autophagic processes. This shows that Drosophila provides an excellent whole-animal model to gain new insights into the function of GGA in the physiological environment of a multicellular organism.

ß-secretase cleavage of the fly amyloid precursor protein is required for glial survival.

ß-secretase (or BACE1) is the key enzyme in the production of ß-amyloid (Aß), which accumulates in the senile plaques characteristic for Alzheimer's disease. Consequently, the lack of BACE1 prevents ß-processing of the amyloid precursor protein and Aß production, which made it a promising target for drug development. However, the loss of BACE1 is also detrimental, leading to myelination defects and altered neuronal activity, functions that have been associated with the cleavage of Neuregulin and a voltage-gated sodium channel subunit. Here we show that the Drosophila ortholog of BACE, dBACE, is required for glial survival. Cell-specific knockdown experiments reveal that this is a non-cell autonomous function, as a knockdown of dBACE in photoreceptor neurons leads to progressive degeneration of glia in their target zone, the lamina. Interestingly, this phenotype is suppressed by the loss of the fly amyloid precursor protein (APPL), whereas a secretion-deficient form of APPL enhances the degeneration. This shows that full-length APPL in neurons promotes the death of neighboring glial cells and that ß-processing of APPL is needed to prevent glial death. These results therefore not only demonstrate a novel function for an APP protein in glia, but they also show this function specifically requires regulation by ß-cleavage.

Chlorogenic Acids, Acting via Calcineurin, Are the Main Compounds in Centella asiatica Extracts That Mediate Resilience to Chronic Stress in Drosophila melanogaster.

Common symptoms of depressive disorders include anhedonia, sleep problems, and reduced physical activity. Drugs used to treat depression mostly aim to increase serotonin signaling but these can have unwanted side effects. Depression has also been treated by traditional medicine using plants like Centella asiatica (CA) and this has been found to be well tolerated. However, very few controlled studies have addressed CA's protective role in depression, nor have the active compounds or mechanisms that mediate this function been identified. To address this issue, we used Drosophila melanogaster to investigate whether CA can improve depression-associated symptoms like anhedonia and decreased climbing activity. We found that a water extract of CA provides resilience to stress induced phenotypes and that this effect is primarily due to mono-caffeoylquinic acids found in CA. Furthermore, we describe that the protective function of CA is due to a synergy between chlorogenic acid and one of its isomers also present in CA. However, increasing the concentration of chlorogenic acid can overcome the requirement for the second isomer. Lastly, we found that chlorogenic acid acts via calcineurin, a multifunctional phosphatase that can regulate synaptic transmission and plasticity and is also involved in neuronal maintenance.

Loss of circadian clock accelerates aging in neurodegeneration-prone mutants.

Circadian clocks generate rhythms in molecular, cellular, physiological, and behavioral processes. Recent studies suggest that disruption of the clock mechanism accelerates organismal senescence and age-related pathologies in mammals. Impaired circadian rhythms are observed in many neurological diseases; however, it is not clear whether loss of rhythms is the cause or result of neurodegeneration, or both. To address this important question, we examined the effects of circadian disruption in Drosophila melanogaster mutants that display clock-unrelated neurodegenerative phenotypes. We combined a null mutation in the clock gene period (per(01)) that abolishes circadian rhythms, with a hypomorphic mutation in the carbonyl reductase gene sniffer (sni(1)), which displays oxidative stress induced neurodegeneration. We report that disruption of circadian rhythms in sni(1) mutants significantly reduces their lifespan compared to single mutants. Shortened lifespan in double mutants was coupled with accelerated neuronal degeneration evidenced by vacuolization in the adult brain. In addition, per(01)sni(1) flies showed drastically impaired vertical mobility and increased accumulation of carbonylated proteins compared to age-matched single mutant flies. Loss of per function does not affect sni mRNA expression, suggesting that these genes act via independent pathways producing additive effects. Finally, we show that per(01) mutation accelerates the onset of brain pathologies when combined with neurodegeneration-prone mutation in another gene, swiss cheese (sws(1)), which does not operate through the oxidative stress pathway. Taken together, our data suggest that the period gene may be causally involved in neuroprotective pathways in aging Drosophila.

Amyloid precursor proteins are protective in Drosophila models of progressive neurodegeneration.

The processing of Amyloid Precursor Proteins (APPs) results in several fragments, including soluble N-terminal ectodomains (sAPPs) and C-terminal intracellular domains (AICD). sAPPs have been ascribed neurotrophic or neuroprotective functions in cell culture, although ß-cleaved sAPPs can have deleterious effects and trigger neuronal cell death. Here we describe a neuroproprotective function of APP and fly APPL (Amyloid Precursor Protein-like) in vivo in several Drosophila mutants with progressive neurodegeneration. We show that expression of the N-terminal ectodomain is sufficient to suppress the progressive degeneration in these mutants and that the secretion of the ectodomain is required for this function. In addition, a protective effect is achieved by expressing kuzbanian (which has α-secretase activity) whereas expression of fly and human BACE aggravates the phenotypes, suggesting that the protective function is specifically mediated by the α-cleaved ectodomain. Furthermore, genetic and molecular studies suggest that the N-terminal fragments interact with full-length APPL activating a downstream signaling pathway via the AICD. Because we show protective effects in mutants that affect different genes (AMP-activated protein kinase, MAP1b, rasGAP), we propose that the protective effect is not due to a genetic interaction between APPL and these genes but a more general aspect of APP proteins. The result that APP proteins and specifically their soluble α-cleaved ectodomains can protect against progressive neurodegeneration in vivo provides support for the hypothesis that a disruption of the physiological function of APP could play a role in the pathogenesis of Alzheimer's Disease.

Analysis of amyloid precursor protein function in Drosophila melanogaster.

Amyloid precursor proteins (APPs) are evolutionary conserved from nematodes to man (Jacobsen and Iverfeldt in Cell Mol Life Sci 66:2299-2318, 2009) suggesting an important physiological function of these proteins. Human APP is a key factor in the pathogenesis of Alzheimer's Disease because its proteolytic processing results in the production of the neurotoxic Aß-peptide, which accumulates in the amyloid plaques characteristic for this disease (Selkoe in Physiol Rev 81(2):741-766, 2001). However, the processing also leads to the production of several other fragments and the role of these products, as well as the function of the full-length protein is so far not well understood. The functional analysis of APP in vertebrates has been hampered by the fact that two close relatives, APLP1 and APLP2, exist and that knock-out mice for APP only show subtle defects. In contrast, invertebrates like Caenorhabditis elegans and Drosophila express only one APP-like protein but whereas a null mutation in the C. elegans APL-1 protein is lethal, flies lacking APPL (Amyloid Precursor Protein-like) are viable but show synaptic defects and behavioral abnormalities. Together with the analyses of flies that express APP proteins ectoptically or xenotopically, these studies show that APP proteins are involved in neuronal differentiation, neuritic outgrowth, and synapse formation. In addition, they play a role in long-term memory formation and maintaining brain integrity in adult flies.

PNPLA6/NTE, an Evolutionary Conserved Phospholipase Linked to a Group of Complex Human Diseases.

Patatin-like phospholipase domain-containing protein 6 (PNPLA6), originally called Neuropathy Target Esterase (NTE), belongs to a family of hydrolases with at least eight members in mammals. PNPLA6/NTE was first identified as a key factor in Organophosphate-induced delayed neuropathy, a degenerative syndrome that occurs after exposure to organophosphates found in pesticides and nerve agents. More recently, mutations in PNPLA6/NTE have been linked with a number of inherited diseases with diverse clinical symptoms that include spastic paraplegia, ataxia, and chorioretinal dystrophy. A conditional knockout of PNPLA6/NTE in the mouse brain results in age-related neurodegeneration, whereas a complete knockout causes lethality during embryogenesis due to defects in the development of the placenta. PNPLA6/NTE is an evolutionarily conserved protein that in Drosophila is called Swiss-Cheese (SWS). Loss of SWS in the fly also leads to locomotory defects and neuronal degeneration that progressively worsen with age. This review will describe the identification of PNPLA6/NTE, its expression pattern, and normal role in lipid homeostasis, as well as the consequences of altered NPLA6/NTE function in both model systems and patients.

Age-dependent effects of blue light exposure on lifespan, neurodegeneration, and mitochondria physiology in Drosophila melanogaster.

Blue light is a predominant component of light emitting devices (LEDs), which are increasingly present in our environment. There is already accumulating evidence that blue light exposure causes damage to retinal cells in vitro and in vivo; however, much less is known about potential effects of blue light on non-retinal cells. That blue light may be detrimental at the organismal level independent from retinal effect was recently shown by findings that it reduces lifespan in worms and also in flies with genetically ablated retinas. Here, we investigated the effects of blue light exposure across the fly lifespan and found that susceptibility to blue light stress is strongly age-dependent. The blue light of the same intensity and duration reduced survival and increased neurodegeneration more significantly in old flies than in young flies. These differences appear to be caused, at least in part, by impairments of mitochondrial respiratory function. We report that blue light significantly reduces the activity of Complex II in the electron transport system and decrease the biochemical activity of succinate dehydrogenase in both young and old flies. In addition, complex I and complex IV activities are reduced by age, as are ATP levels. We therefore propose that older flies are more sensitive to blue light because the light-induced mitochondrial damage potentiates the age-related impairments in energy metabolism that occurs even in darkness. Taken together, our results show that damaging effects of blue light at the organismal level are strongly age dependent and are associated with reduced activity of specific components of energy producing pathways in mitochondria.

Withania somnifera and Centella asiatica Extracts Ameliorate Behavioral Deficits in an In Vivo Drosophila melanogaster Model of Oxidative Stress.

Due to an increase in the aging population, age-related diseases and age-related changes, such as diminished cognition and sleep disturbances, are an increasing health threat. It has been suggested that an increase in oxidative stress underlies many of these changes. Current treatments for these diseases and changes either have low efficacy or have deleterious side effects preventing long-time use. Therefore, alternative treatments that promote healthy aging and provide resilience against these health threats are needed. The herbs Withania somnifera and Centella asiatica may be two such alternatives because both have been connected with reducing oxidative stress and could therefore ameliorate age-related impairments. To test the effects of these herbs on behavioral phenotypes induced by oxidative stress, we used the Drosophila melanogaster sniffer mutant which has high levels of oxidative stress due to reduced carbonyl reductase activity. Effects on cognition and mobility were assessed using phototaxis assays and both, W. somnifera and C. asiatica water extracts improved phototaxis in sniffer mutants. In addition, W. somnifera improved nighttime sleep in male and female sniffer flies and promoted a less fragmented sleep pattern in male sniffer flies. This suggests that W. somnifera and C. asiatica can ameliorate oxidative stress-related changes in behavior and that by doing so they might promote healthy aging in humans.

Withania somnifera Extracts Promote Resilience against Age-Related and Stress-Induced Behavioral Phenotypes in Drosophila melanogaster; a Possible Role of Other Compounds besides Withanolides.

Withania somnifera (WS) extracts have been used in traditional medicine for millennia to promote healthy aging and wellbeing. WS is now also widely used in Western countries as a nutritional supplement to extend healthspan and increase resilience against age-related changes, including sleep deficits and depression. Although human trials have supported beneficial effects of WS, the study designs have varied widely. Plant material is intrinsically complex, and extracts vary widely with the origin of the plant material and the extraction method. Commercial supplements can contain various other ingredients, and the characteristics of the study population can also be varied. To perform maximally controlled experiments, we used plant extracts analyzed for their composition and stability. We then tested these extracts in an inbred Drosophila line to minimize effects of the genetic background in a controlled environment. We found that a water extract of WS (WSAq) was most potent in improving physical fitness, while an ethanol extract (WSE) improved sleep in aged flies. Both extracts provided resilience against stress-induced behavioral changes. WSE contained higher levels of withanolides, which have been proposed to be active ingredients, than WSAq. Therefore, withanolides may mediate the sleep improvement, whereas so-far-unknown ingredients enriched in WSAq likely mediate the effects on fitness and stress-related behavior.

Chronic blue light leads to accelerated aging in Drosophila by impairing energy metabolism and neurotransmitter levels.

Blue light (BL) is becoming increasingly prevalent in artificial illumination, raising concerns about its potential health hazard to humans. In fact, there is evidence suggesting that acute BL exposure may lead to oxidative stress and death of retinal cells specialized for photoreception. On the other hand, recent studies in Drosophila melanogaster demonstrated that chronic BL exposure across lifespan leads to accelerated aging manifested in reduced lifespan and brain neurodegeneration even in flies with genetically ablated eyes, suggesting that BL can damage cells and tissues not specialized for light perception. At the physiological level, BL exposure impairs mitochondria function in flies, but the metabolic underpinnings of these effects have not been studied. Here, we investigated effects of chronic BL on metabolic pathways in heads of eyes absent (eya 2 ) mutant flies in order to focus on extra-retinal tissues. We compared metabolomic profiles in flies kept for 10 or 14 days in constant BL or constant darkness, using LC-MS and GC-MS. Data analysis revealed significant alterations in the levels of several metabolites suggesting that critical cellular pathways are impacted in BL-exposed flies. In particular, dramatic metabolic rearrangements are observed in heads of flies kept in BL for 14 days, including highly elevated levels of succinate but reduced levels of pyruvate and citrate, suggesting impairments in energy production. These flies also show onset of neurodegeneration and our analysis detected significantly reduced levels of several neurotransmitters including glutamate and Gamma-aminobutyric acid (GABA), suggesting that BL disrupts brain homeostasis. Taken together, these data provide novel insights into the mechanisms by which BL interferes with vital metabolic pathways that are conserved between fly and human cells.

Mitochondrial Redox Signaling Is Critical to the Normal Functioning of the Neuronal System.

Mitochondrial dysfunction often leads to neurodegeneration and is considered one of the main causes of neurological disorders, such as Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS) and other age-related diseases. Mitochondrial dysfunction is tightly linked to oxidative stress and accumulating evidence suggests the association between oxidative stress and neurological disorders. However, there is insufficient knowledge about the role of pro-oxidative shift in cellular redox and impairment of redox-sensitive signaling in the development of neurodegenerative pathological conditions. To gain a more complete understanding of the relationship between mitochondria, redox status, and neurodegenerative disorders, we investigated the effect of mitochondrial thiol-dependent peroxidases, peroxiredoxins (Prxs), on the physiological characteristics of flies, which change with pathologies such as PD, ALS and during aging. We previously found that through their ability to sense changes in redox and regulate redox-sensitive signaling, Prxs play a critical role in maintaining global thiol homeostasis, preventing age-related apoptosis and chronic activation of the immune response. We also found that the phenotype of flies under-expressing Prxs in mitochondria shares many characteristics with the phenotype of Drosophila models of neurological disorders such as ALS, including impaired locomotor activity and compromised redox balance. Here, we expanded the study and found that under-expression of mitochondrial Prxs leads to behavioral changes associated with neural function, including locomotor ability, sleep-wake behavior, and temperature-sensitive paralysis. We also found that under-expression of mitochondrial Prxs with a motor-neuron-specific driver, D42-GAL4, was a determining factor in the development of the phenotype of shortened lifespan and impaired motor activity in flies. The results of the study suggest a causal link between mitochondrial Prx activity and the development of neurological disorders and pre-mature aging.