RESUMO
The activation of a neuroendocrine system that induces a surge in steroid production is a conserved initiator of the juvenile-to-adult transition in many animals. The trigger for maturation is the secretion of brain-derived neuropeptides, yet the mechanisms controlling the timely onset of this event remain ill-defined. Here, we show that a regulatory feedback circuit controlling the Drosophila neuropeptide Prothoracicotropic hormone (PTTH) triggers maturation onset. We identify the Ecdysone Receptor (EcR) in the PTTH-expressing neurons (PTTHn) as a regulator of developmental maturation onset. Loss of EcR in these PTTHn impairs PTTH signaling, which delays maturation. We find that the steroid ecdysone dose-dependently affects Ptth transcription, promoting its expression at lower concentrations and inhibiting it at higher concentrations. Our findings indicate the existence of a feedback circuit in which rising ecdysone levels trigger, via EcR activity in the PTTHn, the PTTH surge that generates the maturation-inducing ecdysone peak toward the end of larval development. Because steroid feedback is also known to control the vertebrate maturation-inducing hypothalamic-pituitary-gonadal axis, our findings suggest an overall conservation of the feedback-regulatory neuroendocrine circuitry that controls the timing of maturation initiation.
Assuntos
Proteínas de Drosophila/metabolismo , Hormônios de Inseto/metabolismo , Receptores de Esteroides/metabolismo , Animais , Tamanho Corporal , Drosophila/crescimento & desenvolvimento , Drosophila/metabolismo , Proteínas de Drosophila/antagonistas & inibidores , Proteínas de Drosophila/genética , Ecdisterona/farmacologia , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Hormônios de Inseto/antagonistas & inibidores , Hormônios de Inseto/genética , Larva/crescimento & desenvolvimento , Larva/metabolismo , Metamorfose Biológica , Microscopia de Fluorescência , Neurônios/metabolismo , Interferência de RNA , RNA Guia de Cinetoplastídeos/metabolismo , Receptores de Esteroides/antagonistas & inibidores , Receptores de Esteroides/genética , Transdução de SinaisRESUMO
The human 22q11.2 chromosomal deletion is one of the strongest identified genetic risk factors for schizophrenia. Although the deletion spans a number of known genes, the contribution of each of these to the 22q11.2 deletion syndrome (DS) is not known. To investigate the effect of individual genes within this interval on the pathophysiology associated with the deletion, we analyzed their role in sleep, a behavior affected in virtually all psychiatric disorders, including the 22q11.2 DS. We identified the gene LZTR1 (night owl, nowl) as a regulator of night-time sleep in Drosophila. In humans, LZTR1 has been associated with Ras-dependent neurological diseases also caused by Neurofibromin-1 (Nf1) deficiency. We show that Nf1 loss leads to a night-time sleep phenotype nearly identical to that of nowl loss and that nowl negatively regulates Ras and interacts with Nf1 in sleep regulation. Furthermore, nowl is required for metabolic homeostasis, suggesting that LZTR1 may contribute to the genetic susceptibility to obesity associated with the 22q11.2 DS. Knockdown of nowl or Nf1 in GABA-responsive sleep-promoting neurons elicits the sleep phenotype, and this defect can be rescued by increased GABAA receptor signaling, indicating that Nowl regulates sleep through modulation of GABA signaling. Our results suggest that nowl/LZTR1 may be a conserved regulator of GABA signaling important for normal sleep that contributes to the 22q11.2 DS.
Assuntos
Síndrome da Deleção 22q11/genética , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas de Drosophila/genética , Neurônios GABAérgicos/metabolismo , Neurofibromina 1/genética , Esquizofrenia/genética , Sono/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Drosophila , Proteínas de Drosophila/metabolismo , Neurônios GABAérgicos/fisiologia , Humanos , Neurofibromina 1/metabolismo , Receptores de GABA-A/metabolismo , Fatores de Transcrição/genéticaRESUMO
Stem cell maintenance is established by neighboring niche cells that promote stem cell self-renewal. However, it is poorly understood how stem cell activity is regulated by systemic, tissue-extrinsic signals in response to environmental cues and changes in physiological status. Here, we show that neuropeptide F (NPF) signaling plays an important role in the pathway regulating mating-induced germline stem cell (GSC) proliferation in the fruit fly Drosophila melanogaster. NPF expressed in enteroendocrine cells (EECs) of the midgut is released in response to the seminal-fluid protein sex peptide (SP) upon mating. This midgut-derived NPF controls mating-induced GSC proliferation via ovarian NPF receptor (NPFR) activity, which modulates bone morphogenetic protein (BMP) signaling levels in GSCs. Our study provides a molecular mechanism that describes how a gut-derived systemic factor couples stem cell behavior to physiological status, such as mating, through interorgan communication.
Assuntos
Sistema Digestório/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Células Germinativas/citologia , Neuropeptídeos/metabolismo , Células-Tronco/citologia , Células-Tronco/metabolismo , Animais , Sequência de Bases , Proteínas Morfogenéticas Ósseas/metabolismo , Contagem de Células , Divisão Celular , Proliferação de Células , Ecdisteroides/metabolismo , Células Enteroendócrinas/metabolismo , Feminino , Células Germinativas/metabolismo , Modelos Biológicos , Ovário/metabolismo , Receptores de Neuropeptídeos/metabolismo , Comportamento Sexual Animal , Transdução de SinaisRESUMO
Organisms adapt to changing environments by adjusting their development, metabolism, and behavior to improve their chances of survival and reproduction. To achieve such flexibility, organisms must be able to sense and respond to changes in external environmental conditions and their internal state. Metabolic adaptation in response to altered nutrient availability is key to maintaining energy homeostasis and sustaining developmental growth. Furthermore, environmental variables exert major influences on growth and final adult body size in animals. This developmental plasticity depends on adaptive responses to internal state and external cues that are essential for developmental processes. Genetic studies have shown that the fruit fly Drosophila, similarly to mammals, regulates its metabolism, growth, and behavior in response to the environment through several key hormones including insulin, peptides with glucagon-like function, and steroid hormones. Here we review emerging evidence showing that various environmental cues and internal conditions are sensed in different organs that, via inter-organ communication, relay information to neuroendocrine centers that control insulin and steroid signaling. This review focuses on endocrine regulation of development, metabolism, and behavior in Drosophila, highlighting recent advances in the role of the neuroendocrine system as a signaling hub that integrates environmental inputs and drives adaptive responses.
Assuntos
Adaptação Fisiológica/fisiologia , Drosophila/metabolismo , Drosophila/fisiologia , Animais , Proteínas de Drosophila/metabolismo , Homeostase/fisiologia , Humanos , Hormônios de Inseto/metabolismo , Transdução de Sinais/fisiologiaRESUMO
Behavior and physiology are orchestrated by neuropeptides acting as central neuromodulators and circulating hormones. An outstanding question is how these neuropeptides function to coordinate complex and competing behaviors. In Drosophila, the neuropeptide leucokinin (LK) modulates diverse functions, but mechanisms underlying these complex interactions remain poorly understood. As a first step towards understanding these mechanisms, we delineated LK circuitry that governs various aspects of post-feeding physiology and behavior. We found that impaired LK signaling in Lk and Lk receptor (Lkr) mutants affects diverse but coordinated processes, including regulation of stress, water homeostasis, feeding, locomotor activity, and metabolic rate. Next, we sought to define the populations of LK neurons that contribute to the different aspects of this physiology. We find that the calcium activity in abdominal ganglia LK neurons (ABLKs), but not in the two sets of brain neurons, increases specifically following water consumption, suggesting that ABLKs regulate water homeostasis and its associated physiology. To identify targets of LK peptide, we mapped the distribution of Lkr expression, mined a brain single-cell transcriptome dataset for genes coexpressed with Lkr, and identified synaptic partners of LK neurons. Lkr expression in the brain insulin-producing cells (IPCs), gut, renal tubules and chemosensory cells, correlates well with regulatory roles detected in the Lk and Lkr mutants. Furthermore, these mutants and flies with targeted knockdown of Lkr in IPCs displayed altered expression of insulin-like peptides (DILPs) and transcripts in IPCs and increased starvation resistance. Thus, some effects of LK signaling appear to occur via DILP action. Collectively, our data suggest that the three sets of LK neurons have different targets, but modulate the establishment of post-prandial homeostasis by regulating distinct physiological processes and behaviors such as diuresis, metabolism, organismal activity and insulin signaling. These findings provide a platform for investigating feeding-related neuroendocrine regulation of vital behavior and physiology.
Assuntos
Proteínas de Drosophila/genética , Proteínas de Drosophila/fisiologia , Drosophila melanogaster/genética , Drosophila melanogaster/fisiologia , Neuropeptídeos/genética , Neuropeptídeos/fisiologia , Animais , Animais Geneticamente Modificados , Comportamento Animal/fisiologia , Diurese/genética , Diurese/fisiologia , Proteínas de Drosophila/deficiência , Metabolismo Energético/genética , Metabolismo Energético/fisiologia , Feminino , Perfilação da Expressão Gênica , Técnicas de Silenciamento de Genes , Insulina/fisiologia , Masculino , Atividade Motora/genética , Atividade Motora/fisiologia , Mutação , Neurônios/classificação , Neurônios/fisiologia , Neuropeptídeos/deficiência , Período Pós-Prandial/genética , Período Pós-Prandial/fisiologia , Receptores de Neuropeptídeos/deficiência , Receptores de Neuropeptídeos/genética , Receptores de Neuropeptídeos/fisiologia , Transdução de SinaisRESUMO
Multiple studies have investigated the mechanisms of aggressive behavior in Drosophila; however, little is known about the effects of chronic fighting experience. Here, we investigated if repeated fighting encounters would induce an internal state that could affect the expression of subsequent behavior. We trained wild-type males to become winners or losers by repeatedly pairing them with hypoaggressive or hyperaggressive opponents, respectively. As described previously, we observed that chronic losers tend to lose subsequent fights, while chronic winners tend to win them. Olfactory conditioning experiments showed that winning is perceived as rewarding, while losing is perceived as aversive. Moreover, the effect of chronic fighting experience generalized to other behaviors, such as gap-crossing and courtship. We propose that in response to repeatedly winning or losing aggressive encounters, male flies form an internal state that displays persistence and generalization; fight outcomes can also have positive or negative valence. Furthermore, we show that the activities of the PPL1-γ1pedc dopaminergic neuron and the MBON-γ1pedc>α/ß mushroom body output neuron are required for aversion to an olfactory cue associated with losing fights.
Assuntos
Agressão/fisiologia , Comportamento Animal/fisiologia , Drosophila melanogaster/fisiologia , Comportamento Sexual Animal/fisiologia , Animais , Análise por Conglomerados , Comportamento Competitivo , Cruzamentos Genéticos , Feminino , Masculino , Memória , Movimento , Neurônios/metabolismo , Odorantes , Bulbo Olfatório , Assunção de Riscos , Fatores de TempoRESUMO
The development of sexually dimorphic morphology and the potential for sexually dimorphic behavior in Drosophila are regulated by the Fruitless (Fru) and Doublesex (Dsx) transcription factors. Several direct targets of Dsx have been identified, but direct Fru targets have not been definitively identified. We show that Drosophila leucine-rich repeat G protein-coupled receptor 3 (Lgr3) is regulated by Fru and Dsx in separate populations of neurons. Lgr3 is a member of the relaxin-receptor family and a receptor for Dilp8, necessary for control of organ growth. Lgr3 expression in the anterior central brain of males is inhibited by the B isoform of Fru, whose DNA binding domain interacts with a short region of an Lgr3 intron. Fru A and C isoform mutants had no observed effect on Lgr3 expression. The female form of Dsx (Dsx(F)) separately up- and down-regulates Lgr3 expression in distinct neurons in the abdominal ganglion through female- and male-specific Lgr3 enhancers. Excitation of neural activity in the Dsx(F)-up-regulated abdominal ganglion neurons inhibits female receptivity, indicating the importance of these neurons for sexual behavior. Coordinated regulation of Lgr3 by Fru and Dsx marks a point of convergence of the two branches of the sex-determination hierarchy.
Assuntos
Proteínas de Drosophila/metabolismo , Neurônios/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Fatores Sexuais , Animais , Drosophila , Feminino , MasculinoRESUMO
The coordination of growth with nutritional status is essential for proper development and physiology. Nutritional information is mostly perceived by peripheral organs before being relayed to the brain, which modulates physiological responses. Hormonal signaling ensures this organ-to-organ communication, and the failure of endocrine regulation in humans can cause diseases including obesity and diabetes. In Drosophila melanogaster, the fat body (adipose tissue) has been suggested to play an important role in coupling growth with nutritional status. Here, we show that the peripheral tissue-derived peptide hormone CCHamide-2 (CCHa2) acts as a nutrient-dependent regulator of Drosophila insulin-like peptides (Dilps). A BAC-based transgenic reporter revealed strong expression of CCHa2 receptor (CCHa2-R) in insulin-producing cells (IPCs) in the brain. Calcium imaging of brain explants and IPC-specific CCHa2-R knockdown demonstrated that peripheral-tissue derived CCHa2 directly activates IPCs. Interestingly, genetic disruption of either CCHa2 or CCHa2-R caused almost identical defects in larval growth and developmental timing. Consistent with these phenotypes, the expression of dilp5, and the release of both Dilp2 and Dilp5, were severely reduced. Furthermore, transcription of CCHa2 is altered in response to nutritional levels, particularly of glucose. These findings demonstrate that CCHa2 and CCHa2-R form a direct link between peripheral tissues and the brain, and that this pathway is essential for the coordination of systemic growth with nutritional availability. A mammalian homologue of CCHa2-R, Bombesin receptor subtype-3 (Brs3), is an orphan receptor that is expressed in the islet ß-cells; however, the role of Brs3 in insulin regulation remains elusive. Our genetic approach in Drosophila melanogaster provides the first evidence, to our knowledge, that bombesin receptor signaling with its endogenous ligand promotes insulin production.
Assuntos
Proteínas de Drosophila/biossíntese , Proteínas de Drosophila/genética , Insulina/metabolismo , Insulinas/biossíntese , Neuropeptídeos/genética , Receptores da Bombesina/genética , Receptores Odorantes/genética , Animais , Animais Geneticamente Modificados , Encéfalo/metabolismo , Drosophila melanogaster , Corpo Adiposo/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Células Secretoras de Insulina/metabolismo , Insulinas/genética , Neuropeptídeos/biossíntese , Receptores Odorantes/biossínteseRESUMO
Obesity impairs tissue insulin sensitivity and signaling, promoting type-2 diabetes. Although improving insulin signaling is key to reversing diabetes, the multi-organ mechanisms regulating this process are poorly defined. Here, we screen the secretome and receptome in Drosophila to identify the hormonal crosstalk affecting diet-induced insulin resistance and obesity. We discover a complex interplay between muscle, neuronal, and adipose tissues, mediated by Bone Morphogenetic Protein (BMP) signaling and the hormone Bursicon, that enhances insulin signaling and sugar tolerance. Muscle-derived BMP signaling, induced by sugar, governs neuronal Bursicon signaling. Bursicon, through its receptor Rickets, a Leucine-rich-repeat-containing G-protein coupled receptor (LGR), improves insulin secretion and insulin sensitivity in adipose tissue, mitigating hyperglycemia. In mouse adipocytes, loss of the Rickets ortholog LGR4 blunts insulin responses, showing an essential role of LGR4 in adipocyte insulin sensitivity. Our findings reveal a muscle-neuronal-fat-tissue axis driving metabolic adaptation to high-sugar conditions, identifying LGR4 as a critical mediator in this regulatory network.
Assuntos
Tecido Adiposo , Resistência à Insulina , Obesidade , Receptores Acoplados a Proteínas G , Transdução de Sinais , Animais , Receptores Acoplados a Proteínas G/metabolismo , Receptores Acoplados a Proteínas G/genética , Tecido Adiposo/metabolismo , Camundongos , Obesidade/metabolismo , Insulina/metabolismo , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/genética , Adipócitos/metabolismo , Proteínas Morfogenéticas Ósseas/metabolismo , Músculos/metabolismo , Masculino , Músculo Esquelético/metabolismo , Drosophila melanogaster/metabolismo , Dieta Hiperlipídica/efeitos adversos , Neurônios/metabolismo , Camundongos Endogâmicos C57BLRESUMO
The Drosophila gene yuri gagarin is a complex locus encoding three protein isoform classes that are ubiquitously expressed in the organism. Mutations to the gene affect processes as diverse as gravitactic behavior and spermatogenesis. The larger Yuri isoforms contain extensive coiled-coil regions. Our previous studies indicate that one of the large isoform classes (Yuri-65) is required for formation of specialized F-actin-containing structures generated during spermatogenesis, including the so-called actin "cones" that mediate spermatid individualization. We used the tandem affinity purification of a tagged version of Yuri-65 (the TAP-tagging technique) to identify proteins associated with Yuri-65 in the intact organism. Tropomyosin, primarily as the 284-residue isoform derived from the ubiquitously expressed Tropomyosin 1 gene was thus identified as a major Yuri interaction partner. Co-immunoprecipitation experiments confirmed this interaction. We have established that the stable F-actin cones of spermatogenesis contain Tropomyosin 1 (Tm1) and that in mutant yuri(F64), failure of F-actin cone formation is associated with failure of Tm1 to accumulate at the cone initiation sites. In investigating possible interactions of Tm1 and Yuri in other tissues, we discovered that Tm1 and Yuri frequently colocalize with the endoplasmic reticulum. Tropomyosin has been implicated in actin-mediated membrane trafficking activity in other systems. Our findings suggest that Yuri-Tm1 complexes participate in related functions.
Assuntos
Proteínas de Drosophila/metabolismo , Mapeamento de Interação de Proteínas , Tropomiosina/metabolismo , Actinas , Animais , Drosophila , Proteínas de Drosophila/análise , Retículo Endoplasmático/química , Imunoprecipitação , Ligação Proteica , Transporte Proteico , Tropomiosina/análiseRESUMO
Nutrition is one of the most important influences on growth and the timing of maturational transitions including mammalian puberty and insect metamorphosis. Childhood obesity is associated with precocious puberty, but the assessment mechanism that links body fat to early maturation is unknown. During development, the intake of nutrients promotes signaling through insulin-like systems that govern the growth of cells and tissues and also regulates the timely production of the steroid hormones that initiate the juvenile-adult transition. We show here that the dietary lipid cholesterol, which is required as a component of cell membranes and as a substrate for steroid biosynthesis, also governs body growth and maturation in Drosophila via promoting the expression and release of insulin-like peptides. This nutritional input acts via the nutrient sensor TOR, which is regulated by the Niemann-Pick-type-C 1 (Npc1) cholesterol transporter, in the glia of the blood-brain barrier and cells of the adipose tissue to remotely drive systemic insulin signaling and body growth. Furthermore, increasing intracellular cholesterol levels in the steroid-producing prothoracic gland strongly promotes endoreduplication, leading to an accelerated attainment of a nutritional checkpoint that normally ensures that animals do not initiate maturation prematurely. These findings, therefore, show that a Npc1-TOR signaling system couples the sensing of the lipid cholesterol with cellular and systemic growth control and maturational timing, which may help explain both the link between cholesterol and cancer as well as the connection between body fat (obesity) and early puberty.
Assuntos
Proteínas de Drosophila , Obesidade Infantil , Animais , Colesterol , Drosophila , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Insulina/metabolismo , Larva , Mamíferos , Esteroides/metabolismoRESUMO
Animals must adapt their dietary choices to meet their nutritional needs. How these needs are detected and translated into nutrient-specific appetites that drive food-choice behaviours is poorly understood. Here we show that enteroendocrine cells of the adult female Drosophila midgut sense nutrients and in response release neuropeptide F (NPF), which is an ortholog of mammalian neuropeptide Y-family gut-brain hormones. Gut-derived NPF acts on glucagon-like adipokinetic hormone (AKH) signalling to induce sugar satiety and increase consumption of protein-rich food, and on adipose tissue to promote storage of ingested nutrients. Suppression of NPF-mediated gut signalling leads to overconsumption of dietary sugar while simultaneously decreasing intake of protein-rich yeast. Furthermore, gut-derived NPF has a female-specific function in promoting consumption of protein-containing food in mated females. Together, our findings suggest that gut NPF-to-AKH signalling modulates specific appetites and regulates food choice to ensure homeostatic consumption of nutrients, providing insight into the hormonal mechanisms that underlie nutrient-specific hungers.
Assuntos
Proteínas de Drosophila , Hormônios Gastrointestinais , Feminino , Animais , Drosophila , Apetite , Açúcares , Proteínas de Drosophila/genética , MamíferosRESUMO
The intestine is a central regulator of metabolic homeostasis. Dietary inputs are absorbed through the gut, which senses their nutritional value and relays hormonal information to other organs to coordinate systemic energy balance. However, the gut-derived hormones affecting metabolic and behavioral responses are poorly defined. Here we show that the endocrine cells of the Drosophila gut sense nutrient stress through a mechanism that involves the TOR pathway and in response secrete the peptide hormone allatostatin C, a Drosophila somatostatin homolog. Gut-derived allatostatin C induces secretion of glucagon-like adipokinetic hormone to coordinate food intake and energy mobilization. Loss of gut Allatostatin C or its receptor in the adipokinetic-hormone-producing cells impairs lipid and sugar mobilization during fasting, leading to hypoglycemia. Our findings illustrate a nutrient-responsive endocrine mechanism that maintains energy homeostasis under nutrient-stress conditions, a function that is essential to health and whose failure can lead to metabolic disorders.
Assuntos
Proteínas de Drosophila/metabolismo , Ingestão de Alimentos/fisiologia , Metabolismo Energético/fisiologia , Hormônios Gastrointestinais/metabolismo , Homeostase , Nutrientes/metabolismo , Somatostatina/metabolismo , Animais , Animais Geneticamente Modificados , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Ingestão de Alimentos/genética , Metabolismo Energético/genética , Células Enteroendócrinas/metabolismo , Hormônios Gastrointestinais/genética , Técnicas de Inativação de Genes , Humanos , Hipoglicemia/genética , Hipoglicemia/metabolismo , Hormônios de Inseto/genética , Hormônios de Inseto/metabolismo , Oligopeptídeos/genética , Oligopeptídeos/metabolismo , Ácido Pirrolidonocarboxílico/análogos & derivados , Ácido Pirrolidonocarboxílico/metabolismo , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais/genética , Somatostatina/genética , Análise de SobrevidaRESUMO
Ant colonies are higher-level organisms consisting of specialized reproductive and non-reproductive individuals that differentiate early in development, similar to germ-soma segregation in bilateral Metazoa. Analogous to diverging cell lines, developmental differentiation of individual ants has often been considered in epigenetic terms but the sets of genes that determine caste phenotypes throughout larval and pupal development remain unknown. Here, we reconstruct the individual developmental trajectories of two ant species, Monomorium pharaonis and Acromyrmex echinatior, after obtaining >1,400 whole-genome transcriptomes. Using a new backward prediction algorithm, we show that caste phenotypes can be accurately predicted by genome-wide transcriptome profiling. We find that caste differentiation is increasingly canalized from early development onwards, particularly in germline individuals (gynes/queens) and that the juvenile hormone signalling pathway plays a key role in this process by regulating body mass divergence between castes. We quantified gene-specific canalization levels and found that canalized genes with gyne/queen-biased expression were enriched for ovary and wing functions while canalized genes with worker-biased expression were enriched in brain and behavioural functions. Suppression in gyne larvae of Freja, a highly canalized gyne-biased ovary gene, disturbed pupal development by inducing non-adaptive intermediate phenotypes between gynes and workers. Our results are consistent with natural selection actively maintaining canalized caste phenotypes while securing robustness in the life cycle ontogeny of ant colonies.
Assuntos
Formigas , Animais , Feminino , Formigas/genética , Perfilação da Expressão Gênica , Larva/genética , Fenótipo , TranscriptomaRESUMO
The control of body and organ growth is essential for the development of adults with proper size and proportions, which is important for survival and reproduction. In animals, adult body size is determined by the rate and duration of juvenile growth, which are influenced by the environment. In nutrient-scarce environments in which more time is needed for growth, the juvenile growth period can be extended by delaying maturation, whereas juvenile development is rapidly completed in nutrient-rich conditions. This flexibility requires the integration of environmental cues with developmental signals that govern internal checkpoints to ensure that maturation does not begin until sufficient tissue growth has occurred to reach a proper adult size. The Target of Rapamycin (TOR) pathway is the primary cell-autonomous nutrient sensor, while circulating hormones such as steroids and insulin-like growth factors are the main systemic regulators of growth and maturation in animals. We discuss recent findings in Drosophila melanogaster showing that cell-autonomous environment and growth-sensing mechanisms, involving TOR and other growth-regulatory pathways, that converge on insulin and steroid relay centers are responsible for adjusting systemic growth, and development, in response to external and internal conditions. In addition to this, proper organ growth is also monitored and coordinated with whole-body growth and the timing of maturation through modulation of steroid signaling. This coordination involves interorgan communication mediated by Drosophila insulin-like peptide 8 in response to tissue growth status. Together, these multiple nutritional and developmental cues feed into neuroendocrine hubs controlling insulin and steroid signaling, serving as checkpoints at which developmental progression toward maturation can be delayed. This review focuses on these mechanisms by which external and internal conditions can modulate developmental growth and ensure proper adult body size, and highlights the conserved architecture of this system, which has made Drosophila a prime model for understanding the coordination of growth and maturation in animals.
Assuntos
Tamanho Corporal , Drosophila melanogaster/genética , Regulação da Expressão Gênica no Desenvolvimento , Animais , Drosophila melanogaster/crescimento & desenvolvimento , Drosophila melanogaster/metabolismo , Estágios do Ciclo de Vida , Transdução de SinaisRESUMO
STATEMENT OF PURPOSE: Intentional violent injury is a leading cause of disability and death among young adults in the United States. Hospital-based violence intervention programs (HVIPs), which strive to prevent re-injury through intensive case management, have emerged as a successful and cost-effective strategy to address this issue. Despite the importance of strong therapeutic relationships between clients and their case managers, specific case manager behaviors and attributes that drive the formation of these relationships have not been elucidated. METHODS: A qualitative analysis with a modified grounded theory approach was conducted to gain insight into what clients perceive to be crucial to the formation of a strong client-case manager relationship. Twenty-four semi-structured interviews were conducted with prior clients of our hospital's HVIP. The interviews were analyzed using constant comparison method for recurrent themes. RESULTS: Several key themes emerged from the interviews. Clients emphasized that their case managers must: 1) understand and relate to their sociocultural contexts, 2) navigate the initial in-hospital meeting to successfully create connection, 3) exhibit true compassion and care, 4) serve as role models, 5) act as portals of opportunity, and 6) engender mutual respect and pride. CONCLUSIONS: This study identifies key behaviors of case managers that facilitate the formation of strong therapeutic relationships at the different stages of client recovery. This study's findings emphasize the importance of case managers being culturally aligned with and embedded in their clients' communities. This work can provide a roadmap for case managers to form optimally effective relationships with clients.
Assuntos
Gerentes de Casos/normas , Hospitais , Violência/prevenção & controle , Adulto , Terapia Comportamental , Gerentes de Casos/psicologia , Feminino , Teoria Fundamentada , Humanos , Masculino , Relações Profissional-Paciente , Adulto JovemRESUMO
BACKGROUND: Violence is a public health problem. Hospital-based violence intervention programs such as the San Francisco Wraparound Project (WAP) have been shown to reduce future violent injury. The WAP model employs culturally competent case managers who recruit and enroll violently injured patients as clients. Client acceptance of the WAP intervention is variable, and program success depends on streamlined, timely communication and access to resources. High rates of smartphone usage in populations who are at risk for violent reinjury create an opportunity to design a tailored information and communications technology (ICT) tool to support hospital-based violence intervention programs. OBJECTIVE: Current evidence shows that ICT tools developed in the health care space may not be successful in engaging vulnerable populations. The goal of this study was to use human-centered design methodology to identify the unique communication needs of the clients and case managers at WAP to design a mobile ICT. METHODS: We conducted 15 semi-structured interviews with users: clients, their friends and families, case managers, and other stakeholders in violence intervention and prevention. We used a human-centered design and general inductive approach to thematic analysis to identify themes in the qualitative data, which were extrapolated to insight statements and then reframed into design opportunities. Wireframes of potential mobile ICT app screens were developed to depict these opportunities. RESULTS: Thematic analysis revealed four main insights that were characterized by the opposing needs of our users. (1) A successful relationship is both professional and personal. Clients need this around the clock, but case managers can only support this while on the clock. (2) Communications need to feel personal, but they do not always need to be personalized. (3) Healing is a journey of skill development and lifestyle changes that must be acknowledged, monitored, and rewarded. (4) Social networks need to provide peer support for healing rather than peer pressure to propagate violence. These insights resulted in the following associated design opportunities: (1) Maximize personal connection while controlling access, (2) allow case managers to personalize automated client interactions, (3) hold clients accountable to progress and reward achievements, and (4) build a connected, yet confidential community. CONCLUSIONS: Human-centered design enabled us to identify unique insights and design opportunities that may inform the design of a novel and tailored mobile ICT tool for the WAP community.
Assuntos
Gerentes de Casos , Comunicação , Humanos , São Francisco , Tecnologia , Violência/prevenção & controleRESUMO
BACKGROUND: The severity and disparity of interpersonal violent injury is staggering. Fifty-three per 100,000 African Americans (AA) die of homicide yearly, 20 per 100,000 in Latinos, whereas the rate is 3 per 100,000 in Caucasians. With the ultimate goal of reducing injury recidivism, which now stands at 35% to 50%, we have designed and implemented a hospital-based, case-managed violence prevention program uniquely applicable to trauma centers. The Wraparound Project (WP) seizes the "teachable moment" after injury to implement culturally competent case management (CM) and shepherd clients through risk reduction resources with city and community partners. The purpose of this study was to perform a detailed intermediate evaluation of this multi-modal violence prevention program. We hypothesized that this evaluation would demonstrate feasibility and early programmatic efficacy. We looked to identify areas of programmatic weakness that, if corrected, could strengthen the project and enhance its effectiveness. METHODS: We performed intermediate evaluation on the 18-month-old program. We selected the Centers for Disease Control and Prevention-recommended instrument used for unintentional injury prevention programs and applied it to the WP. The four sequential stages in this methodology are formative, process, impact, and outcome. To test feasibility of WP, we used process evaluation. To evaluate intermediate goals of risk reduction and early efficacy, we used impact evaluation. RESULTS: Four hundred thirty-five people met screening criteria. The two case managers were able to make contact and screen 73% of gun shot victims, and 57% of stab wound victims. Of those not seen, 48% were in the hospital for
Assuntos
Centros de Traumatologia/organização & administração , Violência/prevenção & controle , Ferimentos por Arma de Fogo/prevenção & controle , Ferimentos Perfurantes/prevenção & controle , Etnicidade , Feminino , Humanos , Masculino , Desenvolvimento de Programas , Avaliação de Programas e Projetos de Saúde , São Francisco , Ferimentos por Arma de Fogo/etnologia , Ferimentos por Arma de Fogo/mortalidade , Ferimentos Perfurantes/etnologia , Ferimentos Perfurantes/mortalidade , Adulto JovemRESUMO
Steroid hormones are made from cholesterol and are essential for many developmental processes and disease conditions. The production of these hormones is nutrient dependent and tightly controlled by mechanisms that involve delivery of the precursor molecule cholesterol stored in lipid droplets (LDs). Recent studies have implicated macroautophagy/autophagy, a process regulated by nutrition, in the degradation of LDs and the mobilization of stored lipids. We recently identified an autophagy-dependent mechanism that regulates steroid production via effects on cholesterol trafficking. Through gain- and loss-of-function studies in Drosophila, we found that essential autophagy-related (Atg) genes are required in steroidogenic cells for normal steroid production. Inhibition of autophagy in these cells by knockdown of Atg genes causes strong accumulation of cholesterol in LDs and reduces steroid production, resembling effects seen in some lipid-storage disorders and steroid-dependent cancer conditions. This autophagy-dependent steroid hormone regulation (ASHR) process is regulated by the wts-yki/Warts-Yorkie tumor-suppressor pathway downstream of nutrition, coupling nutrient intake with steroid-dependent developmental growth. This mechanism potentially contributes to the development of certain cancers and lipid-storage disorders and thus may be of great therapeutic relevance.