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1.
J Cell Biol ; 221(6)2022 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-35404399

RESUMO

During tissue morphogenesis, the changes in cell shape, resulting from cell-generated forces, often require active regulation of intracellular trafficking. How mechanical stimuli influence intracellular trafficking and how such regulation impacts tissue mechanics are not fully understood. In this study, we identify an actomyosin-dependent mechanism involving Rab11-mediated trafficking in regulating apical constriction in the Drosophila embryo. During Drosophila mesoderm invagination, apical actin and Myosin II (actomyosin) contractility induces apical accumulation of Rab11-marked vesicle-like structures ("Rab11 vesicles") by promoting a directional bias in dynein-mediated vesicle transport. At the apical domain, Rab11 vesicles are enriched near the adherens junctions (AJs). The apical accumulation of Rab11 vesicles is essential to prevent fragmented apical AJs, breaks in the supracellular actomyosin network, and a reduction in the apical constriction rate. This Rab11 function is separate from its role in promoting apical Myosin II accumulation. These findings suggest a feedback mechanism between actomyosin activity and Rab11-mediated intracellular trafficking that regulates the force generation machinery during tissue folding.


Assuntos
Actomiosina , Proteínas de Drosophila , Drosophila melanogaster , Proteínas rab de Ligação ao GTP , Actomiosina/metabolismo , Animais , Constrição , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriologia , Drosophila melanogaster/metabolismo , Morfogênese , Miosina Tipo II/metabolismo , Proteínas rab de Ligação ao GTP/metabolismo
2.
G3 (Bethesda) ; 12(4)2022 04 04.
Artigo em Inglês | MEDLINE | ID: mdl-35143618

RESUMO

MicroRNAs can have subtle and combinatorial effects on the levels of the targets and pathways they act on. Studying the consequences of a single microRNA knockout often proves difficult as many such knockouts exhibit phenotypes only under stress conditions. This has often led to the hypothesis that microRNAs buffer the effects of intrinsic and environmental stochasticity on gene expression. Observing and understanding this buffering effect entails quantitative analysis of microRNA and target expression in single cells. To this end, we have employed single-molecule fluorescence in situ hybridization, immunofluorescence, and high-resolution confocal microscopy to investigate the effects of miR-9a loss on the expression of the serine-protease Rhomboid in Drosophila melanogaster early embryos. Our single-cell quantitative approach shows that spatially, the rhomboid mRNA pattern is identical in WT and miR-9a knockout embryos. However, we find that the number of mRNA molecules per cell is higher when miR-9a is absent, and the level and temporal accumulation of rhomboid protein shows a more dramatic increase in the miR-9a knockout. Specifically, we see accumulation of rhomboid protein in miR-9a mutants by stage 5, much earlier than in WT. The data, therefore, show that miR-9a functions in the regulation of rhomboid mRNA and protein levels. While further work is required to establish whether rhomboid is a direct target of miR-9 in Drosophila, our results further establish the miR-9 family microRNAs as conserved regulators of timing in neurogenic processes. This study shows the power of single-cell quantification as an experimental tool to study phenotypic consequences of microRNA mis-regulation.


Assuntos
Proteínas de Drosophila , MicroRNAs , Animais , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriologia , Drosophila melanogaster/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Hibridização in Situ Fluorescente , MicroRNAs/genética , RNA Mensageiro/genética
3.
Sci Rep ; 12(1): 2056, 2022 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-35136137

RESUMO

Drosophila melanogaster tumor models are growing in popularity, driven by the high degree of genetic as well as functional conservation to humans. The most common method to measure the effects of a tumor on distant organs of a human cancer patient is to use computed tomography (CT), often used in diagnosing cachexia, a debilitating cancer-induced syndrome most visibly characterized by loss of muscle mass. Successful application of high resolution micro-CT scanning of D. melanogaster was recently reported and we here present the segmentation of all visible larval organs at several stages of tumor development. We previously showed the strong expected reduction in muscle mass as the tumor develops, and we here report a surprisingly strong reduction also in gut and Malpighian tubules (kidney) volume. Time-point of tumor development was found to have a stronger correlation to cachectic organ volume loss than tumor volume, giving support to the previously proposed idea that tumor size does not directly determine degree of cachexia.


Assuntos
Caquexia/patologia , Drosophila melanogaster/genética , Trato Gastrointestinal/patologia , Túbulos de Malpighi/patologia , Neoplasias/patologia , Animais , Modelos Animais de Doenças , Drosophila melanogaster/embriologia , Drosophila melanogaster/crescimento & desenvolvimento , Humanos , Larva/crescimento & desenvolvimento , Tamanho do Órgão/fisiologia , Microtomografia por Raio-X
4.
Nat Commun ; 13(1): 859, 2022 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-35165263

RESUMO

Maternal RNA degradation is critical for embryogenesis and is tightly controlled by maternal RNA-binding proteins. Fragile X mental-retardation protein (FMR1) binds target mRNAs to form ribonucleoprotein (RNP) complexes/granules that control various biological processes, including early embryogenesis. However, how FMR1 recognizes target mRNAs and how FMR1-RNP granule assembly/disassembly regulates FMR1-associated mRNAs remain elusive. Here we show that Drosophila FMR1 preferentially binds mRNAs containing m6A-marked "AGACU" motif with high affinity to contributes to maternal RNA degradation. The high-affinity binding largely depends on a hydrophobic network within FMR1 KH2 domain. Importantly, this binding greatly induces FMR1 granule condensation to efficiently recruit unmodified mRNAs. The degradation of maternal mRNAs then causes granule de-condensation, allowing normal embryogenesis. Our findings reveal that sequence-specific mRNAs instruct FMR1-RNP granules to undergo a dynamic phase-switch, thus contributes to maternal mRNA decay. This mechanism may represent a general principle that regulated RNP-granules control RNA processing and normal development.


Assuntos
Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriologia , Desenvolvimento Embrionário/genética , Proteína do X Frágil de Retardo Mental/metabolismo , Metiltransferases/metabolismo , Estabilidade de RNA/genética , Animais , Grânulos Citoplasmáticos/metabolismo , Embrião não Mamífero/embriologia , Metilação , Domínios Proteicos/genética , RNA Mensageiro/genética , Proteínas de Ligação a RNA/metabolismo
5.
Sci Rep ; 12(1): 292, 2022 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-34997175

RESUMO

Neurogenesis in the Drosophila central brain progresses dynamically in order to generate appropriate numbers of neurons during different stages of development. Thus, a central challenge in neurobiology is to reveal the molecular and genetic mechanisms of neurogenesis timing. Here, we found that neurogenesis is significantly impaired when a novel mutation, Nuwa, is induced at early but not late larval stages. Intriguingly, when the Nuwa mutation is induced in neuroblasts of olfactory projection neurons (PNs) at the embryonic stage, embryonic-born PNs are generated, but larval-born PNs of the same origin fail to be produced. Through molecular characterization and transgenic rescue experiments, we determined that Nuwa is a loss-of-function mutation in Drosophila septin interacting protein 1 (sip1). Furthermore, we found that SIP1 expression is enriched in neuroblasts, and RNAi knockdown of sip1 using a neuroblast driver results in formation of small and aberrant brains. Finally, full-length SIP1 protein and truncated SIP1 proteins lacking either the N- or C-terminus display different subcellular localization patterns, and only full-length SIP1 can rescue the Nuwa-associated neurogenesis defect. Taken together, these results suggest that SIP1 acts as a crucial factor for specific neurogenesis programs in the early developing larval brain.


Assuntos
Encéfalo/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Neurogênese , Neurônios/metabolismo , Animais , Animais Geneticamente Modificados , Encéfalo/embriologia , Proteínas de Drosophila/genética , Drosophila melanogaster/embriologia , Drosophila melanogaster/genética , Regulação da Expressão Gênica no Desenvolvimento , Larva/genética , Larva/metabolismo , Mutação com Perda de Função , Transdução de Sinais
6.
Cells ; 11(2)2022 01 14.
Artigo em Inglês | MEDLINE | ID: mdl-35053396

RESUMO

Patients with Alzheimer's disease suffer from a decrease in brain mass and a prevalence of amyloid-ß plaques. These plaques are thought to play a role in disease progression, but their exact role is not entirely established. We developed an optogenetic model to induce amyloid-ß intracellular oligomerization to model distinct disease etiologies. Here, we examine the effect of Wnt signaling on amyloid in an optogenetic, Drosophila gut stem cell model. We observe that Wnt activation rescues the detrimental effects of amyloid expression and oligomerization. We analyze the gene expression changes downstream of Wnt that contribute to this rescue and find changes in aging related genes, protein misfolding, metabolism, and inflammation. We propose that Wnt expression reduces inflammation through repression of Toll activating factors. We confirm that chronic Toll activation reduces lifespan, but a decrease in the upstream activator Persephone extends it. We propose that the protective effect observed for lithium treatment functions, at least in part, through Wnt activation and the inhibition of inflammation.


Assuntos
Peptídeos beta-Amiloides/toxicidade , Drosophila melanogaster/metabolismo , Intestinos/patologia , Células-Tronco/patologia , Via de Sinalização Wnt , Animais , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/efeitos dos fármacos , Drosophila melanogaster/embriologia , Embrião não Mamífero/efeitos dos fármacos , Embrião não Mamífero/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Longevidade/efeitos dos fármacos , Optogenética , Células-Tronco/efeitos dos fármacos , Células-Tronco/metabolismo , Via de Sinalização Wnt/efeitos dos fármacos , Via de Sinalização Wnt/genética
7.
J Cell Biol ; 221(3)2022 03 07.
Artigo em Inglês | MEDLINE | ID: mdl-35061016

RESUMO

Membrane trafficking plays many roles in morphogenesis, from bulk membrane provision to targeted delivery of proteins and other cargos. In tracheal terminal cells of the Drosophila respiratory system, transport through late endosomes balances membrane delivery between the basal plasma membrane and the apical membrane, which forms a subcellular tube, but it has been unclear how the direction of growth of the subcellular tube with the overall cell growth is coordinated. We show here that endosomes also organize F-actin. Actin assembles around late endocytic vesicles in the growth cone of the cell, reaching from the tip of the subcellular tube to the leading filopodia of the basal membrane. Preventing nucleation of endosomal actin disturbs the directionality of tube growth, uncoupling it from the direction of cell elongation. Severing actin in this area affects tube integrity. Our findings show a new role for late endosomes in directing morphogenesis by organizing actin, in addition to their known role in membrane and protein trafficking.


Assuntos
Actinas/metabolismo , Membrana Celular/metabolismo , Drosophila melanogaster/metabolismo , Endossomos/metabolismo , Animais , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriologia , Endocitose , Proteínas de Fluorescência Verde/metabolismo , Lasers , Frações Subcelulares/metabolismo , Fatores de Tempo
8.
PLoS Genet ; 18(1): e1010002, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34986144

RESUMO

A critical step in animal development is the specification of primordial germ cells (PGCs), the precursors of the germline. Two seemingly mutually exclusive mechanisms are implemented across the animal kingdom: epigenesis and preformation. In epigenesis, PGC specification is non-autonomous and depends on extrinsic signaling pathways. The BMP pathway provides the key PGC specification signals in mammals. Preformation is autonomous and mediated by determinants localized within PGCs. In Drosophila, a classic example of preformation, constituents of the germ plasm localized at the embryonic posterior are thought to be both necessary and sufficient for proper determination of PGCs. Contrary to this longstanding model, here we show that these localized determinants are insufficient by themselves to direct PGC specification in blastoderm stage embryos. Instead, we find that the BMP signaling pathway is required at multiple steps during the specification process and functions in conjunction with components of the germ plasm to orchestrate PGC fate.


Assuntos
Proteínas Morfogenéticas Ósseas/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriologia , Células Germinativas/fisiologia , Animais , Blastoderma , Padronização Corporal , Diferenciação Celular , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Epigênese Genética , Feminino , Células Germinativas/metabolismo , Masculino , Transdução de Sinais
9.
PLoS Biol ; 20(1): e3001494, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34990456

RESUMO

The infiltration of immune cells into tissues underlies the establishment of tissue-resident macrophages and responses to infections and tumors. Yet the mechanisms immune cells utilize to negotiate tissue barriers in living organisms are not well understood, and a role for cortical actin has not been examined. Here, we find that the tissue invasion of Drosophila macrophages, also known as plasmatocytes or hemocytes, utilizes enhanced cortical F-actin levels stimulated by the Drosophila member of the fos proto oncogene transcription factor family (Dfos, Kayak). RNA sequencing analysis and live imaging show that Dfos enhances F-actin levels around the entire macrophage surface by increasing mRNA levels of the membrane spanning molecular scaffold tetraspanin TM4SF, and the actin cross-linking filamin Cheerio, which are themselves required for invasion. Both the filamin and the tetraspanin enhance the cortical activity of Rho1 and the formin Diaphanous and thus the assembly of cortical actin, which is a critical function since expressing a dominant active form of Diaphanous can rescue the Dfos macrophage invasion defect. In vivo imaging shows that Dfos enhances the efficiency of the initial phases of macrophage tissue entry. Genetic evidence argues that this Dfos-induced program in macrophages counteracts the constraint produced by the tension of surrounding tissues and buffers the properties of the macrophage nucleus from affecting tissue entry. We thus identify strengthening the cortical actin cytoskeleton through Dfos as a key process allowing efficient forward movement of an immune cell into surrounding tissues.


Assuntos
Citoesqueleto de Actina/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/imunologia , Macrófagos/fisiologia , Animais , Movimento Celular , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriologia , Genes de Insetos , Genes fos , Análise de Sequência de RNA , Tetraspaninas , Fatores de Transcrição/metabolismo
10.
Dev Biol ; 482: 7-16, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34822846

RESUMO

Regeneration is a response mechanism aiming to reconstruct lost or damaged structures. To achieve this, the cells repopulating the lost tissue often have to change their original identity, a process that involves chromatin remodelling.We have analysed the issue of chromatin remodelling during regeneration in the wing disc of Drosophila . In this disc the ablation of the central region (the pouch) induces the regenerative response of the cells from the lateral region (the hinge), which reconstitute the wing pouch. We have examined euchromatin and heterochromatin histone marks during the process and find that heterochromatin marks disappear but are recovered when regeneration is complete. Euchromatin marks are not modified. We also describe the transcription of two retrotransposons, Roo and F-element in the regenerating cells. We have established a temporal correlation between the alterations of heterochromatin marks and the levels of transcription of two retrotransposons, Roo and F-element, both during embryonic development and in the regeneration process.


Assuntos
Montagem e Desmontagem da Cromatina/genética , Drosophila melanogaster/embriologia , Discos Imaginais/crescimento & desenvolvimento , Regeneração/fisiologia , Retroelementos/genética , Asas de Animais/embriologia , Acetilação , Animais , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Drosophila melanogaster/fisiologia , Eucromatina/metabolismo , Heterocromatina/metabolismo , Histonas/metabolismo , Elementos Nucleotídeos Longos e Dispersos/genética , Metilação , Asas de Animais/crescimento & desenvolvimento
11.
Environ Pollut ; 294: 118646, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34896224

RESUMO

With the rapidly increasing popularity of 5G mobile technology, the effect of radiofrequency radiation on human health has caused public concern. This study explores the effects of a simulated 3.5 GHz radiofrequency electromagnetic radiation (RF-EMF) environment on the development and microbiome of flies under intensities of 0.1 W/m2, 1 W/m2 and 10 W/m2. We found that the pupation percentages in the first 3 days and eclosion rate in the first 2 days were increased under exposure to RF-EMF, and the mean development time was shortened. In a study on third-instar larvae, the expression levels of the heat shock protein genes hsp22, hsp26 and hsp70 and humoral immune system genes AttC, TotC and TotA were all significantly increased. In the oxidative stress system, DuoX gene expression was decreased, sod2 and cat gene expression levels were increased, and SOD and CAT enzyme activity also showed a significant increase. According to the 16S rDNA results, the diversity and species abundance of the microbial community decreased significantly, and according to the functional prediction analysis, the genera Acetobacter and Lactobacillus were significantly increased. In conclusion, 3.5 GHz RF-EMF may enhance thermal stress, oxidative stress and humoral immunity, cause changes in the microbial community, and regulate the insulin/TOR and ecdysteroid signalling pathways to promote fly development.


Assuntos
Drosophila melanogaster , Campos Eletromagnéticos , Microbiota/efeitos da radiação , Ondas de Rádio , Animais , Telefone Celular , Drosophila melanogaster/embriologia , Drosophila melanogaster/microbiologia , Drosophila melanogaster/efeitos da radiação , Expressão Gênica , Proteínas de Choque Térmico , Larva/efeitos da radiação
12.
Nat Commun ; 12(1): 7153, 2021 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-34887421

RESUMO

During Drosophila embryogenesis, the essential pioneer factor Zelda defines hundreds of cis-regulatory regions and in doing so reprograms the zygotic transcriptome. While Zelda is essential later in development, it is unclear how the ability of Zelda to define cis-regulatory regions is shaped by cell-type-specific chromatin architecture. Asymmetric division of neural stem cells (neuroblasts) in the fly brain provide an excellent paradigm for investigating the cell-type-specific functions of this pioneer factor. We show that Zelda synergistically functions with Notch to maintain neuroblasts in an undifferentiated state. Zelda misexpression reprograms progenitor cells to neuroblasts, but this capacity is limited by transcriptional repressors critical for progenitor commitment. Zelda genomic occupancy in neuroblasts is reorganized as compared to the embryo, and this reorganization is correlated with differences in chromatin accessibility and cofactor availability. We propose that Zelda regulates essential transitions in the neuroblasts and embryo through a shared gene-regulatory network driven by cell-type-specific enhancers.


Assuntos
Cromatina/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriologia , Drosophila melanogaster/metabolismo , Proteínas Nucleares/metabolismo , Animais , Diferenciação Celular , Cromatina/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Desenvolvimento Embrionário , Regulação da Expressão Gênica no Desenvolvimento , Proteínas Nucleares/genética , Receptores Notch/genética , Receptores Notch/metabolismo , Células-Tronco/citologia , Células-Tronco/metabolismo
13.
Nat Methods ; 18(12): 1506-1514, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34857936

RESUMO

Mapping the cell phylogeny of a complex multicellular organism relies on somatic mutations accumulated from zygote to adult. Available cell barcoding methods can record about three mutations per barcode, enabling only low-resolution mapping of the cell phylogeny of complex organisms. Here we developed SMALT, a substitution mutation-aided lineage-tracing system that outperforms the available cell barcoding methods in mapping cell phylogeny. We applied SMALT to Drosophila melanogaster and obtained on average more than 20 mutations on a three-kilobase-pair barcoding sequence in early-adult cells. Using the barcoding mutations, we obtained high-quality cell phylogenetic trees, each comprising several thousand internal nodes with 84-93% median bootstrap support. The obtained cell phylogenies enabled a population genetic analysis that estimates the longitudinal dynamics of the number of actively dividing parental cells (Np) in each organ through development. The Np dynamics revealed the trajectory of cell births and provided insight into the balance of symmetric and asymmetric cell division.


Assuntos
Biologia Computacional/métodos , Drosophila melanogaster/metabolismo , Microscopia/métodos , Mutação , Alelos , Animais , Animais Geneticamente Modificados , Divisão Celular , Linhagem da Célula , Replicação do DNA , Drosophila melanogaster/embriologia , Endonucleases/metabolismo , Funções Verossimilhança , Masculino , Mutagênese , Fenótipo , Filogenia , Saccharomyces cerevisiae/genética , Análise de Célula Única
14.
Genetics ; 219(4)2021 12 10.
Artigo em Inglês | MEDLINE | ID: mdl-34849867

RESUMO

Proper development depends on precise spatiotemporal gene expression patterns. Most developmental genes are regulated by multiple enhancers and often by multiple core promoters that generate similar transcripts. We hypothesize that multiple promoters may be required either because enhancers prefer a specific promoter or because multiple promoters serve as a redundancy mechanism. To test these hypotheses, we studied the expression of the knirps locus in the early Drosophila melanogaster embryo, which is mediated by multiple enhancers and core promoters. We found that one of these promoters resembles a typical "sharp" developmental promoter, while the other resembles a "broad" promoter usually associated with housekeeping genes. Using synthetic reporter constructs, we found that some, but not all, enhancers in the locus show a preference for one promoter, indicating that promoters provide both redundancy and specificity. By analyzing the reporter dynamics, we identified specific burst properties during the transcription process, namely burst size and frequency, that are most strongly tuned by the combination of promoter and enhancer. Using locus-sized reporters, we discovered that enhancers with no promoter preference in a synthetic setting have a preference in the locus context. Our results suggest that the presence of multiple promoters in a locus is due both to enhancer preference and a need for redundancy and that "broad" promoters with dispersed transcription start sites are common among developmental genes. They also imply that it can be difficult to extrapolate expression measurements from synthetic reporters to the locus context, where other variables shape a gene's overall expression pattern.


Assuntos
Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Elementos Facilitadores Genéticos , Regiões Promotoras Genéticas , Proteínas Repressoras/genética , Animais , Drosophila melanogaster/embriologia , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Genes Essenciais
15.
PLoS Genet ; 17(11): e1009843, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34780465

RESUMO

Intergenic transcription is a common feature of eukaryotic genomes and performs important and diverse cellular functions. Here, we investigate the iab-8 ncRNA from the Drosophila Bithorax Complex and show that this RNA is able to repress the transcription of genes located at its 3' end by a sequence-independent, transcriptional interference mechanism. Although this RNA is expressed in the early epidermis and CNS, we find that its repressive activity is limited to the CNS, where, in wild-type embryos, it acts on the Hox gene, abd-A, located immediately downstream of it. The CNS specificity is achieved through a 3' extension of the transcript, mediated by the neuronal-specific, RNA-binding protein, ELAV. Loss of ELAV activity eliminates the 3' extension and results in the ectopic activation of abd-A. Thus, a tissue-specific change in the length of a ncRNA is used to generate a precise pattern of gene expression in a higher eukaryote.


Assuntos
Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Proteínas ELAV/genética , Genes Homeobox , Proteínas Nucleares/genética , Fatores de Transcrição/genética , Transcrição Genética , Animais , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Drosophila melanogaster/embriologia , Genes Reporter , MicroRNAs/genética , RNA Longo não Codificante/genética , Deleção de Sequência
16.
Biol Open ; 10(11)2021 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-34842274

RESUMO

Tissues build complex structures like lumens and microvilli to carry out their functions. Most of the mechanisms used to build these structures rely on cells remodelling their apical plasma membranes, which ultimately constitute the specialised compartments. In addition to apical remodelling, these shape changes also depend on the proper attachment of the basal plasma membrane to the extracellular matrix (ECM). The ECM provides cues to establish apicobasal polarity, and it also transduces forces that allow apical remodelling. However, physical crosstalk mechanisms between basal ECM attachment and the apical plasma membrane remain understudied, and the ones described so far are very diverse, which highlights the importance of identifying the general principles. Here, we review apicobasal crosstalk of two well-established models of membrane remodelling taking place during Drosophila melanogaster embryogenesis: amnioserosa cell shape oscillations during dorsal closure and subcellular tube formation in tracheal cells. We discuss how anchoring to the basal ECM affects apical architecture and the mechanisms that mediate these interactions. We analyse this knowledge under the scope of other morphogenetic processes and discuss what aspects of apicobasal crosstalk may represent widespread phenomena and which ones are used to build subsets of specialised compartments.


Assuntos
Comunicação Celular , Drosophila melanogaster/embriologia , Matriz Extracelular/fisiologia , Morfogênese , Animais , Polaridade Celular
17.
Elife ; 102021 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-34605405

RESUMO

PERK is an endoplasmic reticulum (ER) transmembrane sensor that phosphorylates eIF2α to initiate the Unfolded Protein Response (UPR). eIF2α phosphorylation promotes stress-responsive gene expression most notably through the transcription factor ATF4 that contains a regulatory 5' leader. Possible PERK effectors other than ATF4 remain poorly understood. Here, we report that the bZIP transcription factor Xrp1 is required for ATF4-independent PERK signaling. Cell-type-specific gene expression profiling in Drosophila indicated that delta-family glutathione-S-transferases (gstD) are prominently induced by the UPR-activating transgene Rh1G69D. Perk was necessary and sufficient for such gstD induction, but ATF4 was not required. Instead, Perk and other regulators of eIF2α phosphorylation regulated Xrp1 protein levels to induce gstDs. The Xrp1 5' leader has a conserved upstream Open Reading Frame (uORF) analogous to those that regulate ATF4 translation. The gstD-GFP reporter induction required putative Xrp1 binding sites. These results indicate that antioxidant genes are highly induced by a previously unrecognized UPR signaling axis consisting of PERK and Xrp1.


Assuntos
Antioxidantes/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/enzimologia , Glutationa Transferase/metabolismo , Discos Imaginais/enzimologia , eIF-2 Quinase/metabolismo , Animais , Animais Geneticamente Modificados , Sítios de Ligação , Proteínas de Ligação a DNA/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/embriologia , Drosophila melanogaster/genética , Estresse do Retículo Endoplasmático , Fator de Iniciação 2 em Eucariotos/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Glutationa Transferase/genética , Discos Imaginais/embriologia , Fases de Leitura Aberta , Fosforilação , Rodopsina/genética , Rodopsina/metabolismo , Transdução de Sinais , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Resposta a Proteínas não Dobradas , eIF-2 Quinase/genética
18.
Cell Rep ; 37(2): 109830, 2021 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-34644570

RESUMO

Fat stores are critical for reproductive success and may govern maturation initiation. Here, we report that signaling and sensing fat sufficiency for sexual maturation commitment requires the lipid carrier apolipophorin in fat cells and Sema1a in the neuroendocrine prothoracic gland (PG). Larvae lacking apolpp or Sema1a fail to initiate maturation despite accruing sufficient fat stores, and they continue gaining weight until death. Mechanistically, sensing peripheral body-fat levels via the apolipophorin/Sema1a axis regulates endocytosis, endoplasmic reticulum remodeling, and ribosomal maturation for the acquisition of the PG cells' high biosynthetic and secretory capacity. Downstream of apolipophorin/Sema1a, leptin-like upd2 triggers the cessation of feeding and initiates sexual maturation. Human Leptin in the insect PG substitutes for upd2, preventing obesity and triggering maturation downstream of Sema1a. These data show how peripheral fat levels regulate the control of the maturation decision-making process via remodeling of endomembranes and ribosomal biogenesis in gland cells.


Assuntos
Tecido Adiposo/metabolismo , Adiposidade , Drosophila melanogaster/metabolismo , Glândulas Endócrinas/metabolismo , Ribossomos/metabolismo , Maturidade Sexual , Tecido Adiposo/embriologia , Animais , Animais Geneticamente Modificados , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriologia , Drosophila melanogaster/genética , Glândulas Endócrinas/embriologia , Proteínas de Ligação a Ácido Graxo/genética , Proteínas de Ligação a Ácido Graxo/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Glicoproteínas/genética , Glicoproteínas/metabolismo , Larva/genética , Larva/metabolismo , Lipogênese , Transporte Proteico , Ribossomos/genética , Semaforinas/genética , Semaforinas/metabolismo , Transdução de Sinais
19.
Cell Rep ; 37(3): 109874, 2021 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-34686334

RESUMO

Embryos repair wounds rapidly, with no inflammation or scarring, in a process that involves polarization of the actomyosin cytoskeleton. Actomyosin polarization results in the assembly of a contractile cable around the wound that drives wound closure. Here, we demonstrate that a contractile actomyosin cable is not sufficient for rapid wound repair in Drosophila embryos. We show that wounding causes activation of the serine/threonine kinase p38 mitogen-activated protein kinase (MAPK) in the cells adjacent to the wound. p38 activation reduces the levels of wound-induced reactive oxygen species in the cells around the wound, limiting wound size. In addition, p38 promotes an increase in volume in the cells around the wound, thus facilitating the collective cell movements that drive rapid wound healing. Our data indicate that p38 regulates cell volumes through the sodium-potassium-chloride cotransporter NKCC1. Our work reveals cell growth and cell survival as cell behaviors critical for embryonic wound repair.


Assuntos
Proliferação de Células , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/enzimologia , Cicatrização , Ferimentos e Lesões/enzimologia , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo , Animais , Animais Geneticamente Modificados , Tamanho Celular , Proteínas de Drosophila/genética , Drosophila melanogaster/embriologia , Drosophila melanogaster/genética , Ativação Enzimática , Regulação da Expressão Gênica no Desenvolvimento , Miosina Tipo II/metabolismo , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais , Membro 2 da Família 12 de Carreador de Soluto/genética , Membro 2 da Família 12 de Carreador de Soluto/metabolismo , Fatores de Tempo , Ferimentos e Lesões/genética , Ferimentos e Lesões/patologia , Proteínas Quinases p38 Ativadas por Mitógeno/genética
20.
Elife ; 102021 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-34636720

RESUMO

Associative learning allows animals to use past experience to predict future events. The circuits underlying memory formation support immediate and sustained changes in function, often in response to a single example. Larval Drosophila is a genetic model for memory formation that can be accessed at molecular, synaptic, cellular, and circuit levels, often simultaneously, but existing behavioral assays for larval learning and memory do not address individual animals, and it has been difficult to form long-lasting memories, especially those requiring synaptic reorganization. We demonstrate a new assay for learning and memory capable of tracking the changing preferences of individual larvae. We use this assay to explore how activation of a pair of reward neurons changes the response to the innately aversive gas carbon dioxide (CO2). We confirm that when coupled to CO2 presentation in appropriate temporal sequence, optogenetic reward reduces avoidance of CO2. We find that learning is switch-like: all-or-none and quantized in two states. Memories can be extinguished by repeated unrewarded exposure to CO2 but are stabilized against extinction by repeated training or overnight consolidation. Finally, we demonstrate long-lasting protein synthesis dependent and independent memory formation.


Brains learn from experience. They take events from the past, link them together, and use them to predict the future. This is true for fruit flies, Drosophila melanogaster, as well as for humans. One of the main questions in the field of neuroscience is, how does this kind of associative learning happen? Fruit fly larvae can learn to associate a certain smell with a sugar reward. When a group of larvae learn to associate a smell with sugar, most but not all of them will approach that smell in the future. This shows associative learning in action, but it raises a big question. Did the larvae that failed to approach the smell fail to learn, or did they just happen to make a mistake finding the smell? Given another chance, would exactly the same larvae approach the smell as the first time? In other words, did all the larvae learn a little, or did some larvae learn completely and others learn nothing? To find out, Lesar et al. built a computer-controlled maze to test whether individual fruit fly larvae liked or avoided a smell. Whenever a larva reached the middle of the Y-shaped maze, it could choose to go down one of two remaining corridors. One corridor contained air and the other carbon dioxide, a gas they would naturally avoid. Lesar et al. taught each larva to like carbon dioxide by activating reward neurons in its brain while filling the maze with carbon dioxide gas. Studying each larva as it navigated the maze revealed that they learn in a single jump, a 'lightbulb moment'. When Lesar et al. activated the reward neurons, the larva either 'got it' and stopped avoiding carbon dioxide altogether, or it did not. In the second case, it behaved as if it had received no training at all. Classic and modern experiments on people suggest that humans might also learn in jumps, but research on our own brains is challenging. Fruit flies are an excellent model organism to study memory formation because they are easy to breed, and it is easy to manipulate their genetic code. Work in flies has already revealed many of the genes and cells responsible for learning and memory. But, to find the specific brain changes that explain learning, researchers need to know whether the animals they are examining have actually learned something. This new maze could help researchers to identify those individuals, making it easier to find out exactly how associative learning works.


Assuntos
Aprendizagem por Associação , Aprendizagem da Esquiva , Comportamento Animal , Drosophila melanogaster/fisiologia , Memória , Animais , Animais Geneticamente Modificados , Dióxido de Carbono , Proteínas de Drosophila/biossíntese , Proteínas de Drosophila/genética , Drosophila melanogaster/embriologia , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Extinção Psicológica , Larva/genética , Larva/metabolismo , Larva/fisiologia , Odorantes , Percepção Olfatória , Optogenética , Recompensa , Olfato , Fatores de Tempo
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