RESUMO
The isolation and characterization of Drosophila mutations in receptor protein tyrosine kinases (RPTKs) have allowed a detailed analysis of the cellular processes regulated by these proteins. Recent investigations have identified a number of putative ligands involved in the activation of the receptors, and have demonstrated that these RPTKs trigger an evolutionarily conserved biochemical pathway. In addition to molecules previously identified from vertebrate studies, i.e. Grb2, Sos, Ras-Gap, p21ras, Raf, MEK and MAPK, genetic studies have suggested that two novel proteins, the protein tyrosine phosphatase (PTPase) Csw and the transmembrane protein Rho, are involved in RPTK signalling.
Assuntos
Drosophila/fisiologia , Receptores Proteína Tirosina Quinases/metabolismo , Transdução de Sinais , Animais , Evolução Biológica , Drosophila/embriologia , Drosophila/genética , Embrião não Mamífero/fisiologia , Modelos Estruturais , Mutação , Células Fotorreceptoras de Invertebrados/fisiologia , Estrutura Secundária de Proteína , Receptores Proteína Tirosina Quinases/química , Receptores Proteína Tirosina Quinases/genéticaRESUMO
Heparan sulfate proteoglycans (HSPGs) are associated with the cell surface and covalently linked to a small number of long unbranched chains of repeating disaccharides. Numerous biochemical studies of these extracellular matrix molecules have implicated them in a variety of biological phenomena, in particular cell-cell interactions. Recent genetic studies in Drosophila have begun to clarify the function of HSPGs in vivo and recent findings have implicated HSPGs in Wnt, Hedgehog, fibroblast growth factor and transforming growth factor-beta signaling pathways during development.
Assuntos
Proteínas de Drosophila , Drosophila/fisiologia , Proteoglicanas de Heparan Sulfato/metabolismo , Animais , Drosophila/metabolismo , Fatores de Crescimento de Fibroblastos/metabolismo , Proteínas Hedgehog , Proteínas de Insetos/metabolismo , Ligação Proteica , Proteínas Proto-Oncogênicas/fisiologia , Transdução de Sinais , Proteína Wnt1RESUMO
One major challenge in the fields of signal transduction and pattern formation is to understand how multiple signals are integrated to determine cell fates. Two developmental systems, vulval development in Caenorhabditis elegans and axis formation during Drosophila melanogaster oogenesis, require the epidermal growth factor receptor tyrosine kinase and the NOTCH signaling pathways to specify cell fates. Current work in both systems has provided new opportunities to investigate the potential for the cross-talk between these different signaling pathways.
Assuntos
Caenorhabditis elegans/fisiologia , Proteínas de Drosophila , Drosophila melanogaster/fisiologia , Receptores ErbB/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Quinases , Transdução de Sinais/fisiologia , Animais , Feminino , Previsões , Humanos , Oócitos , Receptores de Peptídeos de Invertebrados/metabolismo , Receptores NotchRESUMO
The actin cytoskeleton orders cellular space and transduces many of the forces required for morphogenesis. Here we combine genetics and cell biology to identify genes that control the polarized distribution of actin filaments within the Drosophila follicular epithelium. We find that profilin and cofilin regulate actin-filament formation throughout the cell cortex. In contrast, CAP-a Drosophila homologue of Adenylyl Cyclase Associated Proteins-functions specifically to limit actin-filament formation catalysed by Ena at apical cell junctions. The Abl tyrosine kinase also collaborates in this process. We therefore propose that CAP, Ena and Abl act in concert to modulate the subcellular distribution of actin filaments in Drosophila.
Assuntos
Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Proteínas de Ciclo Celular/metabolismo , Proteínas do Citoesqueleto , Proteínas de Drosophila , Drosophila melanogaster/citologia , Células Epiteliais/metabolismo , Proteínas de Insetos/metabolismo , Proteínas dos Microfilamentos , Citoesqueleto de Actina/ultraestrutura , Actinas/genética , Animais , Polaridade Celular/genética , Proteínas de Ligação a DNA/metabolismo , Drosophila melanogaster/genética , Feminino , Genes abl , Microscopia de Fluorescência , Modelos Biológicos , Folículo Ovariano/citologiaRESUMO
In the March 24 issue of Science, a flurry of papers report on the impending completion of the Drosophila melanogaster genome sequence. This historic achievement is the result of a unique collaboration between the Berkeley Drosophila Genome Project (BDGP), led by Gerry Rubin, and the genomics company Celera, headed by Craig Venter. With its genome almost completely sequenced ahead of schedule, Drosophila is another important model organism to enter the postgenomic age, and represents the largest genome sequenced to date.
Assuntos
Mapeamento Cromossômico/tendências , Drosophila melanogaster/genética , Genoma , Biologia Molecular/tendências , AnimaisRESUMO
The precise regulation of growth factor signalling is crucial to the molecular control of development in Drosophila. Post-translational modification of signalling molecules is one of the mechanisms that modulate developmental signalling specificity. We describe a new gene, fringe connection (frc), that encodes a nucleotide-sugar transporter that transfers UDP-glucuronic acid, UDP-N-acetylglucosamine and possibly UDP-xylose from the cytoplasm into the lumen of the endoplasmic reticulum/Golgi. Embryos with the frc mutation display defects in Wingless, Hedgehog and fibroblast growth factor signalling. Clonal analysis shows that fringe-dependent Notch signalling is disrupted in frc mutant tissue.
Assuntos
Drosophila melanogaster/genética , Glicosiltransferases/metabolismo , Heparitina Sulfato/metabolismo , N-Acetilglucosaminiltransferases , Transdução de Sinais/fisiologia , Sequência de Aminoácidos , Animais , Citoplasma/metabolismo , Proteínas de Drosophila , Drosophila melanogaster/embriologia , Drosophila melanogaster/crescimento & desenvolvimento , Retículo Endoplasmático/metabolismo , Glicosiltransferases/genética , Complexo de Golgi/metabolismo , Humanos , Dados de Sequência Molecular , Morfogênese , Fenótipo , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Uridina Difosfato Ácido Glucurônico/metabolismo , Uridina Difosfato N-Acetilglicosamina/metabolismo , Uridina Difosfato Xilose/metabolismo , Asas de Animais/embriologia , Asas de Animais/crescimento & desenvolvimentoRESUMO
Loss of cell polarity and tissue architecture are characteristics of malignant cancers derived from epithelial tissues. We provide evidence from Drosophila that a group of membrane-associated proteins act in concert to regulate both epithelial structure and cell proliferation. Scribble (Scrib) is a cell junction-localized protein required for polarization of embryonic and, as demonstrated here, imaginal disc and follicular epithelia. We show that the tumor suppressors lethal giant larvae (lgl) and discs-large (dlg) have identical effects on all three epithelia, and that scrib also acts as a tumor suppressor. Scrib and Dlg colocalize and overlap with Lgl in epithelia; activity of all three genes is required for cortical localization of Lgl and junctional localization of Scrib and Dlg. scrib, dlg, and lgl show strong genetic interactions. Our data indicate that the three tumor suppressors act together in a common pathway to regulate cell polarity and growth control.
Assuntos
Polaridade Celular , Proteínas de Drosophila , Drosophila/citologia , Genes Supressores de Tumor , Proteínas de Insetos/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Supressoras de Tumor , Animais , Divisão Celular , Membrana Celular/metabolismo , Transformação Celular Neoplásica , Citoplasma/metabolismo , Drosophila/genética , Drosophila/crescimento & desenvolvimento , Embrião não Mamífero/citologia , Epiderme/embriologia , Epiderme/metabolismo , Epiderme/ultraestrutura , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Feminino , Genes de Insetos , Proteínas de Insetos/genética , Junções Intercelulares/metabolismo , Junções Intercelulares/ultraestrutura , Proteínas de Membrana/genética , Morfogênese , Mutação , FenótipoRESUMO
In Drosophila, the Wingless and Notch signaling pathways function in m any of the same developmental patterning events. Genetic analysis demonstrates that the dishevelled gene, which encodes a molecule previously implicated in implementation of the Winglass signal, interacts antagonistically with Notch and one of its known ligands, Delta. A direct physical interaction between Dishevelled and the Notch carboxyl terminus, distal to the cdc10/ankyrin repeats, suggests a mechanism for this interaction. It is proposed that Dishevelled, in addition to transducing the Wingless signal, blocks Notch signaling directly, thus providing a molecular mechanism for the inhibitory cross talk observed between these pathways.
Assuntos
Proteínas de Drosophila , Drosophila/metabolismo , Proteínas de Membrana/metabolismo , Fosfoproteínas , Proteínas/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Transdução de Sinais , Proteínas Adaptadoras de Transdução de Sinal , Sequência de Aminoácidos , Animais , Células Clonais , Proteínas Desgrenhadas , Drosophila/genética , Drosophila/crescimento & desenvolvimento , Genes de Insetos , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas de Membrana/antagonistas & inibidores , Proteínas de Membrana/genética , Dados de Sequência Molecular , Mutação , Fenótipo , Proteínas/genética , Proteínas Proto-Oncogênicas/genética , Pupa/metabolismo , Receptores Notch , Asas de Animais/citologia , Asas de Animais/crescimento & desenvolvimento , Proteína Wnt1RESUMO
An elegant combination of genetic and biochemical approaches has been used to investigate a variety of signal transduction pathways in developmental processes. Here, we describe the 'terminal' signaling system in the Drosophila embryo, which is responsible for pattern formation in the polar regions of the embryo. This pathway involves a membrane-bound receptor tyrosine kinase (RTK) that is similar to other Drosophila RTKs, such as sevenless, and the mammalian RTKs, such as the epidermal growth factor or platelet-derived growth factor receptors.
Assuntos
Drosophila/genética , Embrião não Mamífero/fisiologia , Transdução de Sinais/genética , Animais , Drosophila/embriologia , Drosophila/metabolismo , Embrião não Mamífero/metabolismo , Idade Gestacional , Transcrição GênicaRESUMO
BACKGROUND: Cell lineage analysis and mosaic analysis of mutations are important techniques that are used to study the development of many organisms. Unfortunately, the methods employed for such analyses are usually inefficient, technically demanding or labor intensive. In Drosophila, the most common methodology used for the generation of mosaic animals is mitotic recombination, which is induced by X-rays. Although this technique is simple, it has the undesirable characteristics of a low efficiency and a high rate of cell death. Furthermore, although a large number of marker systems has been employed to detect mitotic recombinants, none allows easy identification of clones for all cell types. RESULTS: A system is described here that allows a highly efficient generation of clones with the concomitant expression of an easily detectable cellular marker. This method can be applied to cell lineage and mosaic analysis in Drosophila. The site-specific yeast FLP recombinase, under the control of a heat shock-inducible promoter, efficiently catalyses mitotic recombination specifically at the site of a FLP recombination target (FRT). In this system, recombination fuses the alpha-tubulin promoter to the lacZ gene, allowing transcription of the marker. Recombinant cells and their progeny can, therefore, be detected by standard assays for beta-galactosidase. Of particular importance is the fact that only the cells of interest stain, thus allowing their simple detection in any tissue. CONCLUSIONS: We demonstrate that, by intermolecular recombination, we can use FLIP recombinase to generate marked clones efficiently in embryonic, larval and adult tissues. This simple and efficient technique is well suited to cell-lineage analysis and can be easily extended to the generation and detection of mutant clones in mosaic animals.
RESUMO
The Drosophila JAK-STAT pathway and its ligand Unpaired are required for a wide range of developmental processes. Recent results have identified Unpaired as an activator of sex-lethal and revealed a new role for the JAK-STAT pathway in sex determination.
Assuntos
Proteínas de Drosophila , Drosophila melanogaster/genética , Glicoproteínas/genética , Hormônios de Inseto/genética , Proteínas Tirosina Quinases/metabolismo , Proteínas de Ligação a RNA/genética , Processos de Determinação Sexual , Fatores de Transcrição , Animais , Proteínas de Ligação a DNA/metabolismo , Drosophila melanogaster/fisiologia , Feminino , Regulação da Expressão Gênica , Glicoproteínas/metabolismo , Hormônios de Inseto/metabolismo , Masculino , Proteínas de Ligação a RNA/metabolismo , Fator de Transcrição STAT1 , Cromossomos Sexuais/genética , Cromossomos Sexuais/metabolismo , Transdução de Sinais , Transativadores/metabolismoRESUMO
BACKGROUND: A polarised cytoskeleton is required to pattern cellular space, and for many aspects of cell behaviour. While the mechanisms ordering the actin cytoskeleton have been extensively studied in yeast, little is known about the analogous processes in other organisms. We have used Drosophila oogenesis as a model genetic system in which to investigate control of cytoskeletal organisation and cell polarity in multicellular eukaryotes. RESULTS: In a screen to identify genes required for Drosophila oocyte polarity, we isolated a Drosophila homologue of the yeast cyclase-associated protein, CAP. Here we show that CAP preferentially accumulates in the oocyte, where it inhibits actin polymerisation. CAP also has a role in oocyte polarity, as cap mutants fail to establish the proper, asymmetric distribution of mRNA determinants within the oocyte. Similarly in yeast, loss of CAP causes analogous polarity defects, altering the distribution of actin filaments and mRNA determinants. CONCLUSIONS: This study identifies CAP as a new effector of actin dynamics in Drosophila. As CAP controls the spatial distribution of actin filaments and mRNA determinants in both yeast and Drosophila, we conclude that CAP has an evolutionarily conserved function in the genesis of eukaryotic cell polarity.
Assuntos
Actinas/metabolismo , Proteínas de Ciclo Celular/metabolismo , Polaridade Celular/fisiologia , Proteínas do Citoesqueleto , Proteínas de Drosophila , Drosophila/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Proteínas dos Microfilamentos , Oócitos/fisiologia , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/citologia , Proteínas Adaptadoras de Transdução de Sinal , Sequência de Aminoácidos , Animais , Proteínas de Ciclo Celular/genética , Citoesqueleto/metabolismo , Drosophila/genética , Regulação Fúngica da Expressão Gênica , Humanos , Dados de Sequência Molecular , Oogênese/fisiologia , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismoRESUMO
BACKGROUND: The Drosophila eye is composed of about 800 ommatidia, each of which becomes dorsoventrally polarised in a process requiring signalling through the Notch, JAK/STAT and Wingless pathways. These three pathways are thought to act by setting up a gradient of a signalling molecule (or molecules) often referred to as the 'second signal'. Thus far, no candidate for a second signal has been identified. RESULTS: The four-jointed locus encodes a type II transmembrane protein that is expressed in a dorsoventral gradient in the developing eye disc. We have analysed the function and regulation of four-jointed during eye patterning. Loss-of-function clones or ectopic expression of four-jointed resulted in strong non-autonomous defects in ommatidial polarity on the dorsoventral axis. Ectopic expression experiments indicated that localised four-jointed expression was required at the time during development when ommatidial polarity was being determined. In contrast, complete removal of four-jointed function resulted in only a mild ommatidial polarity defect. Finally, we found that four-jointed expression was regulated by the Notch, JAK/STAT and Wingless pathways, consistent with it mediating their effects on ommatidial polarity. CONCLUSIONS: The clonal phenotypes, time of requirement and regulation of four-jointed are consistent with it acting in ommatidial polarity determination as a second signal downstream of Notch, JAK/STAT and Wingless. Interestingly, it appears to act redundantly with unknown factors in this process, providing an explanation for the previous failure to identify a second signal.
Assuntos
Padronização Corporal/genética , Proteínas de Drosophila , Drosophila/embriologia , Olho/embriologia , Proteínas de Insetos/fisiologia , Glicoproteínas de Membrana/fisiologia , Animais , Sequência de Bases , Clonagem Molecular , Proteínas de Ligação a DNA/metabolismo , Olho/metabolismo , Receptores Frizzled , Janus Quinase 3 , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteínas de Membrana/fisiologia , Microscopia Confocal , Dados de Sequência Molecular , Mutação , Reação em Cadeia da Polimerase , Proteínas Tirosina Quinases/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Receptores Acoplados a Proteínas G , Receptores Notch , Fator de Transcrição STAT1 , Transdução de Sinais , Transativadores/metabolismo , Proteína Wnt1RESUMO
The study of serine/threonine kinases in Drosophila is coming of age. Recently several kinases have been identified and their role in cell determination has been established. This review discusses these recent findings and describes the potential for genetic analyses of kinase activity and signal transduction.
Assuntos
Drosophila/genética , Proteínas Quinases/genética , Transdução de Sinais , Animais , Diferenciação Celular/genética , Drosophila/enzimologia , Drosophila/crescimento & desenvolvimento , Proteínas Quinases/metabolismo , Proteínas Serina-Treonina QuinasesRESUMO
Recent studies in Drosophila have identified a single JAK and a single STAT protein. Genetic and biochemical analyses reveal that these two proteins operate in the same signal transduction pathway. Phenotypic analyses of JAK and STAT mutants implicate this pathway in a number of developmental decisions, in particular the regulation of pair-rule genes and fly hematopoiesis.
Assuntos
Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Proteínas de Drosophila , Drosophila/genética , Proteínas do Leite , Proteínas Tirosina Quinases/genética , Proteínas Tirosina Quinases/metabolismo , Transativadores/genética , Transativadores/metabolismo , Animais , Divisão Celular/genética , Drosophila/embriologia , Embrião não Mamífero , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Janus Quinases , Larva , Neoplasias/genética , Fatores de Transcrição STAT , Fator de Transcrição STAT5 , Transdução de Sinais , Fatores de TranscriçãoRESUMO
Within the last three years, Frizzled receptors have risen from obscurity to celebrity status owing to their functional identification as receptors for the ubiquitous family of secreted WNT signaling factors. However, the founding member of the Frizzled family, Drosophila Frizzled (FZ), was cloned almost a decade ago because of its role in regulating cell polarity within the plane of an epithelium. In this review, we consider the role of FZ in this intriguing context. We discuss recent progress towards elucidating mechanisms for the intracellular specification of planar polarity, and further review evidence for models of global polarity regulation at the tissue level. The data suggest that a genetic 'cassette', encoding a set of core signaling components, could pattern hair, bristle and ommatidial planar polarity in Drosophila, and that additional tissue-specific factors might explain the diversity of signal responses. Recently described examples from the nematode and frog suggest that the developmental control of cell polarity by FZ receptors might represent a functionally conserved signaling mechanism.
Assuntos
Polaridade Celular/genética , Proteínas de Drosophila , Drosophila/genética , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Membrana/fisiologia , Animais , Caenorhabditis elegans/genética , Receptores Frizzled , Cabelo/fisiologia , Especificidade de Órgãos , Células Fotorreceptoras de Invertebrados/fisiologia , Receptores Acoplados a Proteínas G , Transdução de Sinais , Xenopus laevis/genéticaRESUMO
A murine v-raf probe, representing the kinase domain, was used to identify two unique loci in Drosophila melanogaster DNA. The most closely related to v-raf was mapped by in situ hybridization to position 2F5-6 (Draf-1) on the X chromosome, whereas the other raf-related gene (Draf-2) was found at position 43A2-5 on chromosome 2. The nucleotide and amino acid homologies of Draf-1 to the kinase domain of v-raf are 61 and 65%, respectively. The large amount of a 3.2-kilobase Draf-1 transcript detected in eggs as a maternal message decreases during embryonic development, and significant steady-state levels are observed throughout the remainder of morphogenesis. We speculate that the Draf-1 locus plays an important role in early embryogenesis.
Assuntos
Drosophila melanogaster/genética , Genes , Oncogenes , Proteínas Quinases/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Mapeamento Cromossômico , Clonagem Molecular , Enzimas de Restrição do DNA , Camundongos , Hibridização de Ácido Nucleico , Plasmídeos , Homologia de Sequência do Ácido NucleicoRESUMO
The Drosophila heat shock cognate gene 4 (hsc4), a member of the hsp70 gene family, encodes an abundant protein, hsc70, that is more similar to the constitutively expressed human protein than the Drosophila heat-inducible hsp70. Developmental expression revealed that hsc4 transcripts are enriched in cells active in endocytosis and those undergoing rapid growth and changes in shape.
Assuntos
Drosophila melanogaster/genética , Proteínas de Choque Térmico/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Drosophila melanogaster/embriologia , Embrião não Mamífero/fisiologia , Éxons , Genes , Humanos , Dados de Sequência Molecular , Família Multigênica , Mapeamento por Restrição , Homologia de Sequência do Ácido Nucleico , Transcrição GênicaRESUMO
We have characterized a Drosophila gene that is a highly conserved homolog of the mammalian cyclic AMP (cAMP)-responsive transcription factors CREB and CREM. Uniquely among Drosophila genes characterized to date, it codes for a cAMP-responsive transcriptional activator. An alternatively spliced product of the same gene is a specific antagonist of cAMP-inducible transcription. Analysis of the splicing pattern of the gene suggests that the gene may be the predecessor of the mammalian CREB and CREM genes.