Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.819
Filtrar
1.
PLoS One ; 15(2): e0227897, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32023281

RESUMO

The optic lobes of the fruit fly Drosophila melanogaster form a highly wired neural network composed of roughly 130.000 neurons of more than 80 different types. How neuronal diversity arises from very few cell progenitors is a central question in developmental neurobiology. We use the optic lobe of the fruit fly as a paradigm to understand how neuroblasts, the neural stem cells, generate multiple neuron types. Although the development of the fly brain has been the subject of extensive research, very little is known about the lineage relationships of the cell types forming the adult optic lobes. Here we perform a large-scale lineage bioinformatics analysis using the graph theory. We generated a large collection of cell clones that genetically label the progeny of neuroblasts and built a database to draw graphs showing the lineage relationships between cell types. By establishing biological criteria that measures the strength of the neuronal relationships and applying community detection tools we have identified eight clusters of neurons. Each cluster contains different cell types that we pose are the product of eight distinct classes of neuroblasts. Three of these clusters match the available lineage data, supporting the predictive value of the analysis. Finally, we show that the neuronal progeny of a neuroblast do not have preferential innervation patterns, but instead become part of different layers and neuropils. Here we establish a new methodology that helps understanding the logic of Drosophila brain development and can be applied to the more complex vertebrate brains.


Assuntos
Linhagem da Célula , Drosophila melanogaster/citologia , Neurônios/citologia , Lobo Óptico de Animais não Mamíferos/citologia , Animais , Células Clonais , Reprodutibilidade dos Testes
2.
Nature ; 579(7797): 101-105, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32103180

RESUMO

Mating and egg laying are tightly cooordinated events in the reproductive life of all oviparous females. Oviposition is typically rare in virgin females but is initiated after copulation. Here we identify the neural circuitry that links egg laying to mating status in Drosophila melanogaster. Activation of female-specific oviposition descending neurons (oviDNs) is necessary and sufficient for egg laying, and is equally potent in virgin and mated females. After mating, sex peptide-a protein from the male seminal fluid-triggers many behavioural and physiological changes in the female, including the onset of egg laying1. Sex peptide is detected by sensory neurons in the uterus2-4, and silences these neurons and their postsynaptic ascending neurons in the abdominal ganglion5. We show that these abdominal ganglion neurons directly activate the female-specific pC1 neurons. GABAergic (γ-aminobutyric-acid-releasing) oviposition inhibitory neurons (oviINs) mediate feed-forward inhibition from pC1 neurons to both oviDNs and their major excitatory input, the oviposition excitatory neurons (oviENs). By attenuating the abdominal ganglion inputs to pC1 neurons and oviINs, sex peptide disinhibits oviDNs to enable egg laying after mating. This circuitry thus coordinates the two key events in female reproduction: mating and egg laying.


Assuntos
Copulação/fisiologia , Drosophila melanogaster/fisiologia , Vias Neurais/fisiologia , Oviposição/fisiologia , Animais , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Feminino , Gânglios Simpáticos/citologia , Masculino , Peptídeos/metabolismo , Células Receptoras Sensoriais/metabolismo , Abstinência Sexual/fisiologia
3.
Adv Exp Med Biol ; 1218: 77-91, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32060872

RESUMO

Notch-mediated lateral inhibition regulates binary cell fate choice, resulting in salt-and-pepper pattern formation during various biological processes. In many cases, Notch signaling acts together with other signaling systems. However, it is not clear what happens when Notch signaling is combined with other signaling systems. Mathematical modeling and the use of a simple biological model system will be essential to address this uncertainty. A wave of differentiation in the Drosophila visual center, the "proneural wave," accompanies the activity of the Notch and EGF signaling pathways. Although all of the Notch signaling components required for lateral inhibition are involved in the proneural wave, no salt-and-pepper pattern is found during the progression of the proneural wave. Instead, Notch is activated along the wave front and regulates proneural wave progression. How does Notch signaling control wave propagation without forming a salt-and-pepper pattern? A mathematical model of the proneural wave, based on biological evidence, has demonstrated that Notch-mediated lateral inhibition is implemented within the proneural wave and that the diffusible action of EGF cancels salt-and-pepper pattern formation. The results from numerical simulation have been confirmed by genetic experiments in vivo and suggest that the combination of Notch-mediated lateral inhibition and EGF-mediated reaction diffusion enables a novel function of Notch signaling that regulates propagation of the proneural wave. Similar mechanisms may play important roles in diverse biological processes found in animal development and cancer pathogenesis.


Assuntos
Diferenciação Celular , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Drosophila melanogaster/metabolismo , Fator de Crescimento Epidérmico/metabolismo , Receptores Notch/metabolismo , Transdução de Sinais , Animais , Regulação da Expressão Gênica no Desenvolvimento , Humanos
4.
PLoS One ; 15(1): e0227554, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31978073

RESUMO

The olfactory pathway integrates the odor information required to generate correct behavioral responses. To address how changes of serotonin signaling in two contralaterally projecting, serotonin-immunoreactive deutocerebral neurons impacts key odorant attraction in Drosophila melanogaster, we selectively alter serotonin signaling using the serotonin transporter with mutated serotonin binding sites in these neurons and analyzed the consequence on odorant-guided food seeking. The expression of the mutated serotonin transporter selectively changed the odorant attraction in an odorant-specific manner. The shift in attraction was not influenced by more up-stream serotonergic mechanisms mediating behavioral inhibition. The expression of the mutated serotonin transporter in CSD neurons did not influence other behaviors associated with food seeking such as olfactory learning and memory or food consumption. We provide evidence that the change in the attraction by serotonin transporter function might be achieved by increased serotonin signaling and by different serotonin receptors. The 5-HT1B receptor positively regulated the attraction to low and negatively regulated the attraction to high concentrations of acetic acid. In contrast, 5-HT1A and 5-HT2A receptors negatively regulated the attraction in projection neurons to high acetic acid concentrations. These results provide insights into how serotonin signaling in two serotonergic neurons selectively regulates the behavioral response to key odorants during food seeking.


Assuntos
Comportamento Animal , Comportamento Alimentar , Proteínas da Membrana Plasmática de Transporte de Serotonina/metabolismo , Animais , Drosophila melanogaster/citologia , Drosophila melanogaster/metabolismo , Serotonina/metabolismo , Transdução de Sinais
5.
PLoS Genet ; 15(12): e1008553, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31841513

RESUMO

Many tissues rely on resident stem cell population to maintain homeostasis. The balance between cell proliferation and differentiation is critical to permit tissue regeneration and prevent dysplasia, particularly following tissue damage. Thus, understanding the cellular processes and genetic programs that coordinate these processes is essential. Here, we report that the conserved transcription factor zfh2 is specifically expressed in Drosophila adult intestinal stem cell and progenitors and is a critical regulator of cell differentiation in this lineage. We show that zfh2 expression is required and sufficient to drive the activation of enteroblasts, the non-proliferative progenitors of absorptive cells. This transition is characterized by the transient formation of thin membrane protrusions, morphological changes characteristic of migratory cells and compensatory stem cell proliferation. We found that zfh2 acts in parallel to insulin signaling and upstream of the TOR growth-promoting pathway during early differentiation. Finally, maintaining zfh2 expression in late enteroblasts blocks terminal differentiation and leads to the formation of highly dysplastic lesions, defining a new late cell differentiation transition. Together, our study greatly improves our understanding of the cascade of cellular changes and regulatory steps that control differentiation in the adult fly midgut and identifies zfh2 as a major player in these processes.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Mucosa Intestinal/citologia , Células-Tronco/citologia , Animais , Diferenciação Celular , Proliferação de Células , Drosophila melanogaster/metabolismo , Feminino , Regulação da Expressão Gênica , Insulina/metabolismo , Absorção Intestinal , Mucosa Intestinal/metabolismo , Transdução de Sinais , Células-Tronco/metabolismo
6.
PLoS Biol ; 17(10): e3000145, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31589603

RESUMO

Male reproductive glands like the mammalian prostate and the paired Drosophila melanogaster accessory glands secrete seminal fluid components that enhance fecundity. In humans, the prostate, stimulated by environmentally regulated endocrine and local androgens, grows throughout adult life. We previously showed that in fly accessory glands, secondary cells (SCs) and their nuclei also grow in adults, a process enhanced by mating and controlled by bone morphogenetic protein (BMP) signalling. Here, we demonstrate that BMP-mediated SC growth is dependent on the receptor for the developmental steroid ecdysone, whose concentration is reported to reflect sociosexual experience in adults. BMP signalling appears to regulate ecdysone receptor (EcR) levels via one or more mechanisms involving the EcR's N terminus or the RNA sequence that encodes it. Nuclear growth in virgin males is dependent on ecdysone, some of which is synthesised in SCs. However, mating induces additional BMP-mediated nuclear growth via a cell type-specific form of hormone-independent EcR signalling, which drives genome endoreplication in a subset of adult SCs. Switching to hormone-independent endoreplication after mating allows growth and secretion to be hyperactivated independently of ecdysone levels in SCs, permitting more rapid replenishment of the accessory gland luminal contents. Our data suggest mechanistic parallels between this physiological, behaviour-induced signalling switch and altered pathological signalling associated with prostate cancer progression.


Assuntos
Proteínas Morfogenéticas Ósseas/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Ecdisona/metabolismo , Genoma de Inseto , Proteínas de Insetos/genética , Receptores de Esteroides/genética , Animais , Proteínas Morfogenéticas Ósseas/metabolismo , Núcleo Celular/metabolismo , Núcleo Celular/ultraestrutura , Copulação/fisiologia , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Drosophila melanogaster/crescimento & desenvolvimento , Drosophila melanogaster/metabolismo , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Insetos/antagonistas & inibidores , Proteínas de Insetos/metabolismo , Masculino , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Receptores de Esteroides/antagonistas & inibidores , Receptores de Esteroides/metabolismo , Transdução de Sinais
7.
PLoS Biol ; 17(10): e3000509, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31613895

RESUMO

The Hippo signalling pathway restricts cell proliferation in animal tissues by inhibiting Yes-associated protein (YAP or YAP1) and Transcriptional Activator with a PDZ domain (TAZ or WW-domain-containing transcriptional activator [WWTR1]), coactivators of the Scalloped (Sd or TEAD) DNA-binding transcription factor. Drosophila has a single YAP/TAZ homolog named Yorkie (Yki) that is regulated by Hippo pathway signalling in response to epithelial polarity and tissue mechanics during development. Here, we show that Yki translocates to the nucleus to drive Sd-mediated cell proliferation in the ovarian follicle cell epithelium in response to mechanical stretching caused by the growth of the germline. Importantly, mechanically induced Yki nuclear localisation also requires nutritionally induced insulin/insulin-like growth factor 1 (IGF-1) signalling (IIS) via phosphatidyl inositol-3-kinase (PI3K), phosphoinositide-dependent kinase 1 (PDK1 or PDPK1), and protein kinase B (Akt or PKB) in the follicular epithelium. We find similar results in the developing Drosophila wing, where Yki becomes nuclear in the mechanically stretched cells of the wing pouch during larval feeding, which induces IIS, but translocates to the cytoplasm upon cessation of feeding in the third instar stage. Inactivating Akt prevents nuclear Yki localisation in the wing disc, while ectopic activation of the insulin receptor, PI3K, or Akt/PKB is sufficient to maintain nuclear Yki in mechanically stimulated cells of the wing pouch even after feeding ceases. Finally, IIS also promotes YAP nuclear localisation in response to mechanical cues in mammalian skin epithelia. Thus, the Hippo pathway has a physiological function as an integrator of epithelial cell polarity, tissue mechanics, and nutritional cues to control cell proliferation and tissue growth in both Drosophila and mammals.


Assuntos
Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Células Epiteliais/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas Nucleares/genética , Fosfatidilinositol 3-Quinase/genética , Proteínas Serina-Treonina Quinases/genética , Proteínas Proto-Oncogênicas c-akt/genética , Transativadores/genética , Proteínas Quinases Dependentes de 3-Fosfoinositídeo/genética , Proteínas Quinases Dependentes de 3-Fosfoinositídeo/metabolismo , Animais , Fenômenos Biomecânicos , Núcleo Celular/metabolismo , Núcleo Celular/ultraestrutura , Polaridade Celular , Proliferação de Células , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Drosophila melanogaster/crescimento & desenvolvimento , Drosophila melanogaster/metabolismo , Células Epiteliais/citologia , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Fator de Crescimento Insulin-Like I/genética , Fator de Crescimento Insulin-Like I/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Larva/citologia , Larva/genética , Larva/crescimento & desenvolvimento , Larva/metabolismo , Mecanotransdução Celular , Camundongos , Proteínas Nucleares/metabolismo , Folículo Ovariano/citologia , Folículo Ovariano/crescimento & desenvolvimento , Folículo Ovariano/metabolismo , Fosfatidilinositol 3-Quinase/metabolismo , Transporte Proteico , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptor de Insulina/genética , Receptor de Insulina/metabolismo , Transativadores/metabolismo , Asas de Animais/citologia , Asas de Animais/crescimento & desenvolvimento , Asas de Animais/metabolismo
8.
Nature ; 574(7779): 559-564, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31645735

RESUMO

Although glucose-sensing neurons were identified more than 50 years ago, the physiological role of glucose sensing in metazoans remains unclear. Here we identify a pair of glucose-sensing neurons with bifurcated axons in the brain of Drosophila. One axon branch projects to insulin-producing cells to trigger the release of Drosophila insulin-like peptide 2 (dilp2) and the other extends to adipokinetic hormone (AKH)-producing cells to inhibit secretion of AKH, the fly analogue of glucagon. These axonal branches undergo synaptic remodelling in response to changes in their internal energy status. Silencing of these glucose-sensing neurons largely disabled the response of insulin-producing cells to glucose and dilp2 secretion, disinhibited AKH secretion in corpora cardiaca and caused hyperglycaemia, a hallmark feature of diabetes mellitus. We propose that these glucose-sensing neurons maintain glucose homeostasis by promoting the secretion of dilp2 and suppressing the release of AKH when haemolymph glucose levels are high.


Assuntos
Encéfalo/metabolismo , Drosophila melanogaster/citologia , Drosophila melanogaster/metabolismo , Glucagon/metabolismo , Glucose/metabolismo , Insulina/metabolismo , Neurônios/metabolismo , Animais , Axônios/metabolismo , Encéfalo/anatomia & histologia , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/anatomia & histologia , Glucose/análise , Hormônios de Inseto/metabolismo , Masculino , Inibição Neural , Vias Neurais , Neuropeptídeos/química , Neuropeptídeos/metabolismo , Neurotransmissores/metabolismo , Oligopeptídeos/metabolismo , Ácido Pirrolidonocarboxílico/análogos & derivados , Ácido Pirrolidonocarboxílico/metabolismo
9.
Nat Commun ; 10(1): 4123, 2019 09 11.
Artigo em Inglês | MEDLINE | ID: mdl-31511511

RESUMO

In adult epithelial stem cell lineages, the precise differentiation of daughter cells is critical to maintain tissue homeostasis. Notch signaling controls the choice between absorptive and entero-endocrine cell differentiation in both the mammalian small intestine and the Drosophila midgut, yet how Notch promotes lineage restriction remains unclear. Here, we describe a role for the transcription factor Klumpfuss (Klu) in restricting the fate of enteroblasts (EBs) in the Drosophila intestine. Klu is induced in Notch-positive EBs and its activity restricts cell fate towards the enterocyte (EC) lineage. Transcriptomics and DamID profiling show that Klu suppresses enteroendocrine (EE) fate by repressing the action of the proneural gene Scute, which is essential for EE differentiation. Loss of Klu results in differentiation of EBs into EE cells. Our findings provide mechanistic insight into how lineage commitment in progenitor cell differentiation can be ensured downstream of initial specification cues.


Assuntos
Linhagem da Célula , Proteínas de Ligação a DNA/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Enterócitos/citologia , Intestinos/citologia , Células-Tronco/citologia , Fatores de Transcrição/metabolismo , Animais , Carcinogênese/metabolismo , Carcinogênese/patologia , Diferenciação Celular , Proliferação de Células , Modelos Biológicos , Ligação Proteica , Receptores Notch/metabolismo , Transdução de Sinais , Células-Tronco/metabolismo
10.
Adv Mater ; 31(42): e1903599, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31486161

RESUMO

Fluorescence imaging is an indispensable tool in biology, with applications ranging from single-cell to whole-animal studies and with live mapping of neuronal activity currently receiving particular attention. To enable fluorescence imaging at cellular scale in freely moving animals, miniaturized microscopes and lensless imagers are developed that can be implanted in a minimally invasive fashion; but the rigidity, size, and potential toxicity of the involved light sources remain a challenge. Here, narrowband organic light-emitting diodes (OLEDs) are developed and used for fluorescence imaging of live cells and for mapping of neuronal activity in Drosophila melanogaster via genetically encoded Ca2+ indicators. In order to avoid spectral overlap with fluorescence from the sample, distributed Bragg reflectors are integrated onto the OLEDs to block their long-wavelength emission tail, which enables an image contrast comparable to conventional, much bulkier mercury light sources. As OLEDs can be fabricated on mechanically flexible substrates and structured into arrays of cell-sized pixels, this work opens a new pathway for the development of implantable light sources that enable functional imaging and sensing in freely moving animals.


Assuntos
Cálcio/metabolismo , Microscopia de Fluorescência/instrumentação , Semicondutores , Animais , Drosophila melanogaster/citologia , Camundongos , Células NIH 3T3 , Neurônios/metabolismo
11.
Results Probl Cell Differ ; 67: 277-321, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31435800

RESUMO

The first 3 h of Drosophila melanogaster embryo development are exemplified by rapid nuclear divisions within a large syncytium, transforming the zygote to the cellular blastoderm after 13 successive cleavage divisions. As the syncytial embryo develops, it relies on centrosomes and cytoskeletal dynamics to transport nuclei, maintain uniform nuclear distribution throughout cleavage cycles, ensure generation of germ cells, and coordinate cellularization. For the sake of this review, we classify six early embryo stages that rely on processes coordinated by the centrosome and its regulation of the cytoskeleton. The first stage features migration of one of the female pronuclei toward the male pronucleus following maturation of the first embryonic centrosomes. Two subsequent stages distribute the nuclei first axially and then radially in the embryo. The remaining three stages involve centrosome-actin dynamics that control cortical plasma membrane morphogenesis. In this review, we highlight the dynamics of the centrosome and its role in controlling the six stages that culminate in the cellularization of the blastoderm embryo.


Assuntos
Centrossomo/metabolismo , Drosophila melanogaster/citologia , Drosophila melanogaster/embriologia , Embrião não Mamífero/citologia , Animais , Blastoderma , Núcleo Celular
13.
Cell Mol Life Sci ; 76(21): 4309-4317, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31300869

RESUMO

Adult stem cells have a unique capacity to renew themselves and generate differentiated cells that are needed in the body. These cells are recruited and maintained by the surrounding microenvironment, known as the stem cell niche, during organ development. Thus, the stem cell niche is required for proper tissue homeostasis, and its dysregulation is associated with tumorigenesis and tissue degeneration. The identification of niche components and the mechanisms that regulate niche establishment and maintenance, however, are just beginning to be uncovered. Germline stem cells (GSCs) of the Drosophila ovary provide an excellent model for studying the stem cell niche in vivo because of their well-characterized cell biology and the availability of genetic tools. In this review, we introduce the ovarian GSC niche, and the key signaling pathways for niche precursor segregation, niche specification, and niche extracellular environment establishment and niche maintenance that are involved in regulating niche size during development and adulthood.


Assuntos
Drosophila melanogaster , Células-Tronco de Oogônios/citologia , Nicho de Células-Tronco/genética , Animais , Diferenciação Celular/genética , Drosophila melanogaster/citologia , Drosophila melanogaster/fisiologia , Feminino , Células Germinativas/citologia , Células Germinativas/fisiologia , Células-Tronco de Oogônios/fisiologia , Ovário/citologia , Transdução de Sinais/genética
14.
PLoS Genet ; 15(7): e1008062, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31295251

RESUMO

Stem cells rely on instructive cues from their environment. Alterations in microenvironments might contribute to tissue dysfunction and disease pathogenesis. Germline stem cells (GSCs) and cyst stem cells (CySC) in Drosophila testes are normally maintained in the apical area by the testicular hub. In this study, we found that reproduction leads to accumulation of early differentiating daughters of CySCs and GSCs in the testes of aged male flies, due to hyperactivation of Jun-N-terminal kinase (JNK) signaling to maintain self-renewal gene expression in the differentiating cyst cells. JNK activity is normally required to maintain CySCs in the apical niche. A muscle sheath surrounds the Drosophila testis to maintain its long coiled structure. Importantly, reproduction triggers accumulation of the tumor necrosis factor (TNF) Eiger in the testis muscle to activate JNK signaling via the TNF receptor Grindelwald in the cyst cells. Reducing Eiger activity in the testis muscle sheath suppressed reproduction-induced differentiation defects, but had little effect on testis homeostasis of unmated males. Our results reveal that reproduction in males provokes a dramatic shift in the testicular microenvironment, which impairs tissue homeostasis and spermatogenesis in the testes.


Assuntos
Células-Tronco Germinativas Adultas/citologia , Drosophila melanogaster/fisiologia , Reprodução , Células-Tronco Germinativas Adultas/metabolismo , Animais , Diferenciação Celular , Autorrenovação Celular , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Feminino , Homeostase , Sistema de Sinalização das MAP Quinases , Masculino , Proteínas de Membrana/metabolismo , Comportamento Sexual Animal , Espermatogênese , Nicho de Células-Tronco , Testículo/citologia , Testículo/metabolismo
15.
Nat Commun ; 10(1): 2951, 2019 07 04.
Artigo em Inglês | MEDLINE | ID: mdl-31273212

RESUMO

Epithelial-mesenchymal transition (EMT) is an essential process both in physiological and pathological contexts. Intriguingly, EMT is often associated with tissue invagination during development; however, the impact of EMT on tissue remodeling remain unexplored. Here, we show that at the initiation of the EMT process, cells produce an apico-basal force, orthogonal to the surface of the epithelium, that constitutes an important driving force for tissue invagination in Drosophila. When EMT is ectopically induced, cells starting their delamination generate an orthogonal force and induce ectopic folding. Similarly, during mesoderm invagination, cells undergoing EMT generate an apico-basal force through the formation of apico-basal structures of myosin II. Using both laser microdissection and in silico physical modelling, we show that mesoderm invagination does not proceed if apico-basal forces are impaired, indicating that they constitute driving forces in the folding process. Altogether, these data reveal the mechanical impact of EMT on morphogenesis.


Assuntos
Drosophila melanogaster/embriologia , Transição Epitelial-Mesenquimal , Epitélio/embriologia , Morfogênese , Animais , Polaridade Celular , Simulação por Computador , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Drosophila melanogaster/metabolismo , Embrião não Mamífero/citologia , Embrião não Mamífero/metabolismo , Epitélio/metabolismo , Mesoderma/citologia , Mesoderma/embriologia , Mesoderma/metabolismo , Modelos Moleculares , Miosina Tipo II/metabolismo
16.
BMC Mol Cell Biol ; 20(Suppl 1): 7, 2019 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-31284878

RESUMO

BACKGROUND: The calmodulin-regulated spectrin-associated proteins (CAMSAPs) belong to a conserved protein family, which includes members that bind the polymerizing mcrotubule (MT) minus ends and remain associated with the MT lattice formed by minus end polymerization. Only one of the three mammalian CAMSAPs, CAMSAP1, localizes to the mitotic spindle but its function is unclear. In Drosophila, there is only one CAMSAP, named Patronin. Previous work has shown that Patronin stabilizes the minus ends of non-mitotic MTs and is required for proper spindle elongation. However, the precise role of Patronin in mitotic spindle assembly is poorly understood. RESULTS: Here we have explored the role of Patronin in Drosophila mitosis using S2 tissue culture cells as a model system. We show that Patronin associates with different types of MT bundles within the Drosophila mitotic spindle, and that it is required for their stability. Imaging of living cells expressing Patronin-GFP showed that Patronin displays a dynamic behavior. In prometaphase cells, Patronin accumulates on short segments of MT bundles located near the chromosomes. These Patronin "seeds" extend towards the cell poles and stop growing just before reaching the poles. Our data also suggest that Patronin localization is largely independent of proteins acting at the MT minus ends such as Asp and Klp10A. CONCLUSION: Our results suggest a working hypothesis about the mitotic role of Patronin. We propose that Patronin binds the minus ends within MT bundles, including those generated from the walls of preexisting MTs via the augmin-mediated pathway. This would help maintaining MT association within the mitotic bundles, thereby stabilizing the spindle structure. Our data also raise the intriguing possibility that the minus ends of bundled MTs can undergo a limited polymerization.


Assuntos
Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Proteínas Associadas aos Microtúbulos/metabolismo , Mitose/fisiologia , Animais , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular , Centrossomo/metabolismo , Segregação de Cromossomos , Cinesina/metabolismo , Microtúbulos/metabolismo , Polimerização , Ligação Proteica , Fuso Acromático/metabolismo
17.
Phys Rev E ; 99(6-1): 062401, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31330615

RESUMO

Mechanical strain and stress play a major role in biological processes such as wound healing or morphogenesis. To assess this role quantitatively, fixed or live images of tissues are acquired at a cellular precision in large fields of views. To exploit these data, large numbers of cells have to be analyzed to extract cell shape anisotropy and cell size. Most frequently, this is performed through detailed individual cell contour determination, using so-called segmentation computer programs, complemented if necessary by manual detection and error corrections. However, a coarse-grained and faster technique can be recommended in at least three situations: first, when detailed information on individual cell contours is not required; for instance, in studies which require only coarse-grained average information on cell anisotropy. Second, as an exploratory step to determine whether full segmentation can be potentially useful. Third, when segmentation is too difficult, for instance due to poor image quality or too large a cell number. We developed a user-friendly, Fourier-transform-based image analysis pipeline. It is fast (typically 10^{4} cells per minute with a current laptop computer) and suitable for time, space, or ensemble averages. We validate it on one set of artificial images and on two sets of fully segmented images, one from a Drosophila pupa and the other from a chicken embryo; the pipeline results are robust. Perspectives include in vitro tissues, nonbiological cellular patterns such as foams and xyz stacks.


Assuntos
Forma Celular , Epitélio/diagnóstico por imagem , Análise de Fourier , Imagem Molecular , Animais , Anisotropia , Fenômenos Biomecânicos , Tamanho Celular , Embrião de Galinha , Drosophila melanogaster/citologia , Pupa/citologia , Estresse Mecânico , Fatores de Tempo
18.
Genomics Proteomics Bioinformatics ; 17(3): 297-304, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31195140

RESUMO

Drosophila neural development undergoes extensive chromatin remodeling and precise epigenetic regulation. However, the roles of chromatin remodeling in establishment and maintenance of cell identity during cell fate transition remain enigmatic. Here, we compared the changes in gene expression, as well as the dynamics of nucleosome positioning and key histone modifications between the four major neural cell types during Drosophila neural development. We find that the neural progenitors can be separated from the terminally differentiated cells based on their gene expression profiles, whereas nucleosome distribution in the flanking regions of transcription start sites fails to identify the relationships between the progenitors and the differentiated cells. H3K27me3 signal in promoters and enhancers can not only distinguish the progenitors from the differentiated cells but also identify the differentiation path of the neural stem cells (NSCs) to the intermediate progenitor cells to the glial cells. In contrast, H3K9ac signal fails to identify the differentiation path, although it activates distinct sets of genes with neuron-specific and glia-related functions during the differentiation of the NSCs into neurons and glia, respectively. Together, our study provides novel insights into the crucial roles of chromatin remodeling in determining cell type during Drosophila neural development.


Assuntos
Diferenciação Celular/genética , Drosophila melanogaster/citologia , Histonas/metabolismo , Lisina/metabolismo , Neuroglia/citologia , Sequências Reguladoras de Ácido Nucleico/genética , Células-Tronco/citologia , Animais , Drosophila melanogaster/genética , Elementos Facilitadores Genéticos/genética , Epigênese Genética , Histonas/genética , Metilação , Células-Tronco Neurais/citologia , Células-Tronco Neurais/metabolismo , Neurogênese , Neuroglia/metabolismo , Nucleossomos/metabolismo , Regiões Promotoras Genéticas/genética , Células-Tronco/metabolismo , Sítio de Iniciação de Transcrição
19.
PLoS Genet ; 15(5): e1008072, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31150390

RESUMO

Sister centromere fusion is a process unique to meiosis that promotes co-orientation of the sister kinetochores, ensuring they attach to microtubules from the same pole during metaphase I. We have found that the kinetochore protein SPC105R/KNL1 and Protein Phosphatase 1 (PP1-87B) regulate sister centromere fusion in Drosophila oocytes. The analysis of these two proteins, however, has shown that two independent mechanisms maintain sister centromere fusion. Maintenance of sister centromere fusion by SPC105R depends on Separase, suggesting cohesin proteins must be maintained at the core centromeres. In contrast, maintenance of sister centromere fusion by PP1-87B does not depend on either Separase or WAPL. Instead, PP1-87B maintains sister centromeres fusion by regulating microtubule dynamics. We demonstrate that this regulation is through antagonizing Polo kinase and BubR1, two proteins known to promote stability of kinetochore-microtubule (KT-MT) attachments, suggesting that PP1-87B maintains sister centromere fusion by inhibiting stable KT-MT attachments. Surprisingly, C(3)G, the transverse element of the synaptonemal complex (SC), is also required for centromere separation in Pp1-87B RNAi oocytes. This is evidence for a functional role of centromeric SC in the meiotic divisions, that might involve regulating microtubule dynamics. Together, we propose two mechanisms maintain co-orientation in Drosophila oocytes: one involves SPC105R to protect cohesins at sister centromeres and another involves PP1-87B to regulate spindle forces at end-on attachments.


Assuntos
Proteínas de Ciclo Celular/genética , Centrômero/metabolismo , Proteínas Cromossômicas não Histona/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Meiose , Microtúbulos/metabolismo , Proteína Fosfatase 1/genética , Animais , Proteínas de Ciclo Celular/metabolismo , Centrômero/ultraestrutura , Proteínas Cromossômicas não Histona/metabolismo , Segregação de Cromossomos , Cromossomos de Insetos/química , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Drosophila melanogaster/metabolismo , Feminino , Regulação da Expressão Gênica , Microtúbulos/ultraestrutura , Oócitos/citologia , Oócitos/metabolismo , Proteína Fosfatase 1/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Separase/genética , Separase/metabolismo , Fuso Acromático/metabolismo , Fuso Acromático/ultraestrutura , Complexo Sinaptonêmico/metabolismo , Complexo Sinaptonêmico/ultraestrutura
20.
Artigo em Inglês | MEDLINE | ID: mdl-31150868

RESUMO

The anoxia-tolerant fruit fly, Drosophila melanogaster, has routinely been used to examine cellular mechanisms responsible for anoxic and oxidative stress resistance. Nitric oxide (NO), an important cellular signaling molecule, and its downstream activation of cGMP-dependent protein kinase G (PKG) has been implicated as a protective mechanism against ischemic injury in diverse animal models from insects to mammals. In Drosophila, increased PKG signaling results in increased survival of animals exposed to anoxic stress. To determine if activation of the NO/cGMP/PKG pathway is protective at the cellular level, the present study employed a pharmacological protocol to mimic hypoxic injury in Drosophila S2 cells. The commonly used S2 cell line was derived from a primary culture of late stage (20-24 h old) Drosophila melanogaster embryos. Hypoxic stress was induced by exposure to either sodium azide (NaN3) or cobalt chloride (CoCl2). During chemical hypoxic stress, NO/cGMP/PKG activation protected against cell death and this mechanism involved modulation of downstream mitochondrial ATP-sensitive potassium ion channels (mitoKATP). The cellular protection afforded by NO/cGMP/PKG activation during ischemia-like stress may be an adaptive cytoprotective mechanism and modulation of this signaling cascade could serve as a potential therapeutic target for protection against hypoxia or ischemia-induced cellular injury.


Assuntos
Proteínas Quinases Dependentes de GMP Cíclico/metabolismo , GMP Cíclico/metabolismo , Drosophila melanogaster/citologia , Hipóxia/metabolismo , Óxido Nítrico/metabolismo , Animais , Hipóxia Celular/efeitos dos fármacos , Linhagem Celular , Cobalto/toxicidade , GMP Cíclico/análogos & derivados , GMP Cíclico/farmacologia , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/efeitos dos fármacos , Ativação Enzimática , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Canais de Potássio/metabolismo , Transdução de Sinais/efeitos dos fármacos , Estresse Fisiológico
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA