RESUMO
Sleep and feeding are vital homeostatic behaviors, and disruptions in either can result in substantial metabolic consequences. Distinct neuronal manipulations in Drosophila can dissociate sleep loss from subsequent homeostatic rebound, offering an optimal platform to examine the precise interplay between these fundamental behaviors. Here, we investigate concomitant changes in sleep and food intake in individual animals, as well as respiratory metabolic expenditure, that accompany behavioral and genetic manipulations that induce sleep loss in Drosophila melanogaster. We find that sleep disruptions resulting in energy deficit through increased metabolic expenditure and manifested as increased food intake were consistently followed by rebound sleep. In contrast, "soft" sleep loss, which does not induce rebound sleep, is not accompanied by increased metabolism and food intake. Our results demonstrate that homeostatic sleep rebound is linked to energy deficit accrued during sleep loss. Collectively, these findings support the notion that sleep functions to conserve energy and highlight the need to examine the effects of metabolic therapeutics on sleep.
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Mutations in Cullin-3 (Cul3), a conserved gene encoding a ubiquitin ligase, are strongly associated with autism spectrum disorder (ASD). Here, we characterize ASD-related pathologies caused by neuron-specific Cul3 knockdown in Drosophila. We confirmed that neuronal Cul3 knockdown causes short sleep, paralleling sleep disturbances in ASD. Because sleep defects and ASD are linked to metabolic dysregulation, we tested the starvation response of neuronal Cul3 knockdown flies; they starved faster and had lower triacylglyceride levels than controls, suggesting defects in metabolic homeostasis. ASD is also characterized by increased biomarkers of oxidative stress; we found that neuronal Cul3 knockdown increased sensitivity to hyperoxia, an exogenous oxidative stress. Additional hallmarks of ASD are deficits in social interactions and learning. Using a courtship suppression assay that measures social interactions and memory of prior courtship, we found that neuronal Cul3 knockdown reduced courtship and learning compared to controls. Finally, we found that neuronal Cul3 depletion alters the anatomy of the mushroom body, a brain region required for memory and sleep. Taken together, the ASD-related phenotypes of neuronal Cul3 knockdown flies establish these flies as a genetic model to study molecular and cellular mechanisms underlying ASD pathology, including metabolic and oxidative stress dysregulation and neurodevelopment.
Assuntos
Transtorno do Espectro Autista , Proteínas de Drosophila , Animais , Transtorno do Espectro Autista/genética , Proteínas Culina/genética , Proteínas Culina/metabolismo , Drosophila/genética , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Neurônios/metabolismoRESUMO
An epidemic of obesity has affected large portions of the world, increasing the risk of developing many different age-associated diseases, including cancer, cardiovascular disease, and diabetes. In contrast with the prevailing notion that "a calorie is just a calorie," there are clear differences, within and between individuals, in the metabolic response to different macronutrient sources. Recent findings challenge this oversimplification; calories from different macronutrient sources or consumed at different times of day have metabolic effects beyond their value as fuel. Here, we summarize discussions conducted at a recent NIH workshop that brought together experts in calorie restriction, macronutrient composition, and time-restricted feeding to discuss how dietary composition and feeding schedule impact whole-body metabolism, longevity, and healthspan. These discussions may provide insights into the long-sought molecular mechanisms engaged by calorie restriction to extend lifespan, lead to novel therapies, and potentially inform the development of a personalized food-as-medicine approach to healthy aging.
Assuntos
Envelhecimento Saudável , Humanos , Ingestão de Energia , Dieta , Restrição Calórica , Obesidade , Longevidade/fisiologiaRESUMO
Time-restricted feeding (TRF) has recently gained interest as a potential anti-ageing treatment for organisms from Drosophila to humans1-5. TRF restricts food intake to specific hours of the day. Because TRF controls the timing of feeding, rather than nutrient or caloric content, TRF has been hypothesized to depend on circadian-regulated functions; the underlying molecular mechanisms of its effects remain unclear. Here, to exploit the genetic tools and well-characterized ageing markers of Drosophila, we developed an intermittent TRF (iTRF) dietary regimen that robustly extended fly lifespan and delayed the onset of ageing markers in the muscles and gut. We found that iTRF enhanced circadian-regulated transcription and that iTRF-mediated lifespan extension required both circadian regulation and autophagy, a conserved longevity pathway. Night-specific induction of autophagy was both necessary and sufficient to extend lifespan on an ad libitum diet and also prevented further iTRF-mediated lifespan extension. By contrast, day-specific induction of autophagy did not extend lifespan. Thus, these results identify circadian-regulated autophagy as a critical contributor to iTRF-mediated health benefits in Drosophila. Because both circadian regulation and autophagy are highly conserved processes in human ageing, this work highlights the possibility that behavioural or pharmaceutical interventions that stimulate circadian-regulated autophagy might provide people with similar health benefits, such as delayed ageing and lifespan extension.
Assuntos
Autofagia/fisiologia , Ritmo Circadiano/fisiologia , Drosophila melanogaster/fisiologia , Comportamento Alimentar/fisiologia , Longevidade/fisiologia , Envelhecimento/genética , Envelhecimento/efeitos da radiação , Animais , Autofagia/genética , Biomarcadores , Relógios Circadianos/efeitos da radiação , Ritmo Circadiano/genética , Ritmo Circadiano/efeitos da radiação , Escuridão , Drosophila melanogaster/genética , Drosophila melanogaster/efeitos da radiação , Comportamento Alimentar/efeitos da radiação , Feminino , Longevidade/genética , Longevidade/efeitos da radiação , Masculino , Fatores de TempoRESUMO
Many animals rely on taste to identify nutritious foods and to avoid the consumption of harmful substances. The tastes of macronutrients, as well as of non-caloric micronutrients such as sodium and calcium, contribute to the regulation of ingestive behavior1,2. Whether vitamins also affect feeding behavior through taste is less clear. Here, we show that the fly Drosophila melanogaster has a strong preference for consuming a vitamin-containing diet: both sexes show a preference for folic acid, whereas only females show a preference for riboflavin. Females show a preference with vitamin concentrations as low as â¼10 nM - at least 50,000-fold lower than the concentration needed for sucrose preference. This female vitamin preference requires inputs from external and internal taste organs, suggesting that post-ingestive signals, in the absence of gustatory input, are insufficient to actuate preferential consumption of vitamin-containing diets. Our studies demonstrate that vitamin perception is an important determinant of feeding behavior.
Assuntos
Drosophila melanogaster , Drosophila , Animais , Feminino , Masculino , Paladar/fisiologia , Percepção Gustatória , VitaminasRESUMO
Neurofibromatosis type 1 is a chronic multisystemic genetic disorder that results from loss of function in the neurofibromin protein. Neurofibromin may regulate metabolism, though the underlying mechanisms remain largely unknown. Here we show that neurofibromin regulates metabolic homeostasis in Drosophila via a discrete neuronal circuit. Loss of neurofibromin increases metabolic rate via a Ras GAP-related domain-dependent mechanism, increases feeding homeostatically, and alters lipid stores and turnover kinetics. The increase in metabolic rate is independent of locomotor activity, and maps to a sparse subset of neurons. Stimulating these neurons increases metabolic rate, linking their dynamic activity state to metabolism over short time scales. Our results indicate that neurofibromin regulates metabolic rate via neuronal mechanisms, suggest that cellular and systemic metabolic alterations may represent a pathophysiological mechanism in neurofibromatosis type 1, and provide a platform for investigating the cellular role of neurofibromin in metabolic homeostasis.
Assuntos
Neurofibromina 1/metabolismo , Neurônios/metabolismo , Animais , Drosophila , Feminino , Cinética , Metabolismo dos Lipídeos/fisiologia , MasculinoRESUMO
The prototypical M13 peptidase, human Neprilysin, functions as a transmembrane "ectoenzyme" that cleaves neuropeptides that regulate e.g. glucose metabolism, and has been linked to type 2 diabetes. The M13 family has undergone a remarkable, and conserved, expansion in the Drosophila genus. Here, we describe the function of Drosophila melanogaster Neprilysin-like 15 (Nepl15). Nepl15 is likely to be a secreted protein, rather than a transmembrane protein. Nepl15 has changes in critical catalytic residues that are conserved across the Drosophila genus and likely renders the Nepl15 protein catalytically inactive. Nevertheless, a knockout of the Nepl15 gene reveals a reduction in triglyceride and glycogen storage, with the effects likely occurring during the larval feeding period. Conversely, flies overexpressing Nepl15 store more triglycerides and glycogen. Protein modeling suggests that Nepl15 is able to bind and sequester peptide targets of catalytically active Drosophila M13 family members, peptides that are conserved in humans and Drosophila, potentially providing a novel mechanism for regulating the activity of neuropeptides in the context of lipid and carbohydrate homeostasis.
Assuntos
Metabolismo dos Carboidratos , Drosophila melanogaster/metabolismo , Metabolismo dos Lipídeos , Neprilisina/metabolismo , Animais , Catálise , Corpo Adiposo/metabolismo , Feminino , Técnicas de Silenciamento de Genes , Homeostase , Masculino , Neprilisina/química , Neprilisina/genética , Neuropeptídeos/metabolismo , Ligação Proteica , Conformação Proteica , ProteóliseRESUMO
Factors that mediate ethanol preference in Drosophila melanogaster are not well understood. A major confound has been the use of diverse methods to estimate ethanol consumption. We measured fly consumptive ethanol preference on base diets varying in nutrients, taste and ethanol concentration. Both sexes showed an ethanol preference that was abolished on high nutrient concentration diets. Additionally, manipulating total food intake without altering the nutritive value of the base diet or the ethanol concentration was sufficient to evoke or eliminate ethanol preference. Absolute ethanol intake and food volume consumed were stronger predictors of ethanol preference than caloric intake or the dietary caloric content. Our findings suggest that the effect of the base diet on ethanol preference is largely mediated by total consumption associated with the delivery medium, which ultimately determines the level of ethanol intake. We speculate that a physiologically relevant threshold for ethanol intake is essential for preferential ethanol consumption.
Assuntos
Consumo de Bebidas Alcoólicas , Drosophila melanogaster , Animais , Dieta , Ingestão de Energia , Etanol , Feminino , MasculinoRESUMO
The Hippo pathway regulates cell proliferation and organ size through control of the transcriptional regulators YAP (yes-associated protein) and TAZ. Upon extracellular stimuli such as cell-cell contact, the pathway negatively regulates YAP through cytoplasmic sequestration. Under conditions of low cell density, YAP is nuclear and associates with enhancer regions and gene promoters. YAP is mainly described as a transcriptional activator of genes involved in cell proliferation and survival. Using a genome-wide approach, we show here that, in addition to its known function as a transcriptional activator, YAP functions as a transcriptional repressor by interacting with the multifunctional transcription factor Yin Yang 1 (YY1) and Polycomb repressive complex member enhancer of zeste homologue 2 (EZH2). YAP colocalized with YY1 and EZH2 on the genome to transcriptionally repress a broad network of genes mediating a host of cellular functions, including repression of the cell-cycle kinase inhibitor p27, whose role is to functionally promote contact inhibition. This work unveils a broad and underappreciated aspect of YAP nuclear function as a transcriptional repressor and highlights how loss of contact inhibition in cancer is mediated in part through YAP repressive function. SIGNIFICANCE: This study provides new insights into YAP as a broad transcriptional repressor of key regulators of the cell cycle, in turn influencing contact inhibition and tumorigenesis.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Ciclo Celular/genética , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Neoplasias/genética , Fatores de Transcrição/metabolismo , Transcrição Gênica , Fator de Transcrição YY1/metabolismo , Animais , Carcinogênese/genética , Fracionamento Celular , Linhagem Celular Tumoral , Núcleo Celular/metabolismo , Proliferação de Células/genética , Inibidor de Quinase Dependente de Ciclina p27/genética , Feminino , Regulação Neoplásica da Expressão Gênica , Redes Reguladoras de Genes/genética , Humanos , Camundongos , Neoplasias/patologia , Regiões Promotoras Genéticas/genética , Transdução de Sinais/genética , Ensaios Antitumorais Modelo de Xenoenxerto , Proteínas de Sinalização YAPRESUMO
Perceived palatability of food controls caloric intake. Sweet taste is the primary means of detecting the carbohydrate content of food. Surprisingly, sweet taste sensitivity is responsive to extrinsic factors like diet, and this occurs by unknown mechanisms. Here, we describe an unbiased proteomic investigation into sweet taste sensitivity in the fruit fly. We identify a dopamine/cyclic AMP (cAMP)/CREB axis acting within sweet taste neurons that controls taste perception but is largely dispensable for acute taste transduction. This pathway modulates sweet taste perception in response to both sensory- and nutrient-restricted diets and converges on PGC1α, a critical regulator of metabolic health and lifespan. By electrophysiology, we found that enhanced sucrose taste sensitivity was the result of heightened sweet taste intensity and that PGC1α was both necessary and sufficient for this effect. Together, we provide the first molecular insight into how diet-induced taste perception is regulated within the sweet taste neuron.
Assuntos
Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Percepção Gustatória/fisiologia , Paladar/fisiologia , Animais , Dieta , Dopamina/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Ingestão de Energia , Preferências Alimentares/fisiologia , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/fisiologia , Proteômica , Transdução de Sinais , Sacarose/metabolismoRESUMO
Longitudinal measurements of food intake remain a challenge in Drosophila studies of nutrition and behavior. Here, we report an improved method for measuring fly food intake using dye-labeled food and excreta quantification (EX-Q). Reducing the surface area of the medium maximized excreta recovery and the accuracy in estimating total consumption. The EX-Q method is compatible with agar-based medium and makes it possible to measure consumption over an extended period and at multiple time points without sacrificing flies. Using EX-Q, we revealed nutrient- and age-specific features of Drosophila feeding behavior. Daily consumption of a chemically defined diet was relatively consistent over the first 25 days of adulthood. Omitting amino acids or vitamins from the diet reduced consumption in both sexes, whereas omitting sugars or cholesterol primarily affected female food intake. Our results demonstrate EX-Q as a simple, reliable, and nondestructive method for longitudinal studies of solid food intake in Drosophila.
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Peptidylarginine deiminase (PAD) modifies peptidylarginine and converts it to peptidylcitrulline in the presence of elevated calcium. Protein modification can lead to severe changes in protein structure and function, and aberrant PAD activity is linked to human pathologies. While PAD homologs have been discovered in vertebrates-as well as in protozoa, fungi, and bacteria-none have been identified in Drosophila melanogaster, a simple and widely used animal model for human diseases. Here, we describe the development of a human PAD overexpression model in Drosophila. We established fly lines harboring human PAD2 or PAD4 transgenes for ectopic expression under control of the GAL4/UAS system. We show that ubiquitous or nervous system expression of PAD2 or PAD4 have minimal impact on fly lifespan, fecundity, and the response to acute heat stress. Although we did not detect citrullinated proteins in fly homogenates, fly-expressed PAD4-but not PAD2-was active in vitro upon Ca2+ supplementation. The transgenic fly lines may be valuable in future efforts to develop animal models of PAD-related disorders and for investigating the biochemistry and regulation of PAD function.
Assuntos
Drosophila melanogaster/genética , Proteína-Arginina Desiminase do Tipo 2/genética , Proteína-Arginina Desiminase do Tipo 4/genética , Transgenes , Animais , Animais Geneticamente Modificados/genética , Drosophila melanogaster/fisiologia , Feminino , Fertilidade , Resposta ao Choque Térmico , Humanos , Longevidade , Masculino , Regulação para CimaRESUMO
Taste drives appropriate food preference and intake. In Drosophila, taste neurons are housed in both external and internal organs, but the latter have been relatively underexplored. Here, we report that Poxn mutants with a minimal taste system of pharyngeal neurons can avoid many aversive tastants, including bitter compounds, acid, and salt, suggesting that pharyngeal taste is sufficient for rejecting intake of aversive compounds. Optogenetic activation of selected pharyngeal bitter neurons during feeding events elicits changes in feeding parameters that can suppress intake. Functional dissection experiments indicate that multiple classes of pharyngeal neurons are involved in achieving behavioral avoidance, by virtue of being inhibited or activated by aversive tastants. Tracing second-order pharyngeal circuits reveals two main relay centers for processing pharyngeal taste inputs. Together, our results suggest that the pharynx can control the ingestion of harmful compounds by integrating taste input from different classes of pharyngeal neurons.
Assuntos
Aprendizagem da Esquiva , Células Quimiorreceptoras/metabolismo , Proteínas de Drosophila/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Fatores de Transcrição Box Pareados/metabolismo , Paladar , Animais , Agentes Aversivos/farmacologia , Células Quimiorreceptoras/efeitos dos fármacos , Células Quimiorreceptoras/fisiologia , Proteínas de Drosophila/genética , Drosophila melanogaster , Preferências Alimentares , Proteínas do Tecido Nervoso/genética , Fatores de Transcrição Box Pareados/genética , Faringe/citologia , Percepção GustatóriaRESUMO
Microbes can extend Drosophila melanogaster life span by contributing to the nutritional value of malnourishing fly culture medium. The beneficial effect of microbes during malnutrition is dependent on their individual ability to proliferate in the fly environment and is mimicked by lifelong supplementation of equivalent levels of heat-killed microbes or dietary protein, suggesting that microbes can serve directly as a protein-rich food source. Here, we use nutritionally rich fly culture medium to demonstrate how changes in dietary composition influence monocolonized fly life span; microbes that extend fly life span on malnourishing diets can shorten life on rich diets. The mechanisms employed by microbes to affect host health likely differ on low- or high-nutrient diets. Our results demonstrate how Drosophila-associated microbes can positively or negatively influence fly life span depending on the nutritional environment. Although controlled laboratory environments allow focused investigations on the interaction between fly microbiota and nutrition, the relevance of these studies is not straightforward, because it is difficult to mimic the nutritional ecology of natural Drosophila-microbe interactions. As such, caution is needed in designing and interpreting fly-microbe experiments and before categorizing microbes into specific symbiotic roles based on results obtained from experiments testing limited conditions.IMPORTANCED. melanogaster ingests microorganisms growing within its rotting vegetation diet. Some of these microbes form associations with flies, while others pass through the gut with meals. Fly-microbe-diet interactions are dynamic, and changes to the fly culture medium can influence microbial growth in the overall environment. In turn, these alterations in microbial growth may not only impact the nutritional value of fly meals but also modulate behavior and health, at least in part due to direct contributions to fly nutrition. The interactive ecology between flies, microbes, and their environment can cause a specific microbe to be either beneficial or detrimental to fly life span, indicating that the environment should be considered a key influential factor in host-microbe interactions.
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Drosophila melanogaster/microbiologia , Interações entre Hospedeiro e Microrganismos , Longevidade , Microbiota , Nutrientes , Fenômenos Fisiológicos da Nutrição Animal , Animais , Drosophila melanogaster/metabolismo , SimbioseRESUMO
The FDA approved drug rapamycin can prolong lifespan in diverse species and delay the onset of age-related disease in mammals. However, a number of fundamental questions remain unanswered regarding the mechanisms by which rapamycin modulates age-related pathophysiology and lifespan. Alterations in the gut microbiota can impact host physiology, metabolism and lifespan. While recent studies have shown that rapamycin treatment alters the gut microbiota in aged animals, the causal relationships between rapamycin treatment, microbiota dynamics and aging are not known. Here, using Drosophila as a model organism, we show that rapamycin-mediated alterations in microbiota dynamics in aged flies are associated with improved markers of intestinal and muscle aging. Critically, however, we show that the beneficial effects of rapamycin treatment on tissue aging and lifespan are not dependent upon the microbiota. Indeed, germ-free flies show delayed onset of intestinal barrier dysfunction, improved proteostasis in aged muscles and a significant lifespan extension upon rapamycin treatment. In contrast, genetic inhibition of autophagy impairs the ability of rapamycin to mediate improved gut health and proteostasis during aging. Our results indicate that rapamycin-mediated modulation of the microbiota in aged animals is not causally required to slow tissue and organismal aging.
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Drosophila/efeitos dos fármacos , Microbioma Gastrointestinal/efeitos dos fármacos , Longevidade/efeitos dos fármacos , Sirolimo/farmacologia , Animais , Animais Geneticamente Modificados , Autofagia/efeitos dos fármacos , Autofagia/genética , Proteína Homóloga à Proteína-1 Relacionada à Autofagia/genética , Drosophila/microbiologia , Drosophila/fisiologia , Proteínas de Drosophila/genética , Feminino , Técnicas de Silenciamento de Genes , Vida Livre de Germes , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/metabolismo , Mucosa Intestinal/microbiologia , Masculino , Modelos Animais , Permeabilidade/efeitos dos fármacos , Proteostase/efeitos dos fármacos , Proteostase/genética , Interferência de RNARESUMO
Despite the widespread consumption of ethanol, mechanisms underlying its anesthetic effects remain uncertain. n-Alcohols induce anesthesia up to a specific chain length and then lose potency-an observation known as the "chain-length cutoff effect." This cutoff effect is thought to be mediated by alcohol binding sites on proteins such as ion channels, but where these sites are for long-chain alcohols and how they mediate a cutoff remain poorly defined. In animals, the enzyme phospholipase D (PLD) has been shown to generate alcohol metabolites (e.g., phosphatidylethanol) with a cutoff, but no phenotype has been shown connecting PLD to an anesthetic effect. Here we show loss of PLD blocks ethanol-mediated hyperactivity in Drosophila melanogaster (fruit fly), demonstrating that PLD mediates behavioral responses to alcohol in vivo. Furthermore, the metabolite phosphatidylethanol directly competes for the endogenous PLD product phosphatidic acid at lipid-binding sites within potassium channels [e.g., TWIK-related K+ channel type 1 (K2P2.1, TREK-1)]. This gives rise to a PLD-dependent cutoff in TREK-1. We propose an alcohol pathway where PLD produces lipid-alcohol metabolites that bind to and regulate downstream effector molecules including lipid-regulated potassium channels.
Assuntos
Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Etanol/metabolismo , Proteínas de Ligação a RNA/metabolismo , Animais , Sítios de Ligação/fisiologia , Células Cultivadas , Glicerofosfolipídeos/metabolismo , Ácidos Fosfatídicos/metabolismo , Fosfolipase D/metabolismo , Canais de Potássio de Domínios Poros em Tandem/metabolismoRESUMO
In Drosophila, Pox-neuro (Poxn) is a member of the Paired box (Pax) gene family that encodes transcription factors with characteristic paired DNA-binding domains. During embryonic development, Poxn is expressed in sensory organ precursor (SOP) cells of poly-innervated external sensory (p-es) organs and is important for specifying p-es organ identity (chemosensory) as opposed to mono-innervated external sensory (m-es) organs (mechanosensory). In Poxn mutants, there is a transformation of chemosensory bristles into mechanosensory bristles. As a result, these mutants have often been considered to be entirely taste-blind, and researchers have used them in this capacity to investigate physiological and behavioral functions that act in a taste-independent manner. However, recent studies show that only external taste bristles are transformed in Poxn mutants whereas all internal pharyngeal taste neurons remain intact, raising concerns about interpretations of experimental results using Poxn mutants as taste-blind flies. In this review, we summarize the value of Poxn mutants in advancing our knowledge of taste-enriched genes and feeding behaviors, and encourage revisiting some of the conclusions about taste-independent nutrient-sensing mechanisms derived from these mutants. Lastly, we highlight that Poxn mutant flies remain a valuable tool for probing the function of the relatively understudied pharyngeal taste neurons in sensing meal properties and regulating feeding behaviors.