RESUMEN
Asymmetric stem cell division (ASCD) is a key mechanism in development, cancer, and stem cell biology. Drosophila neural stem cells, called neuroblasts (NBs), divide asymmetrically through intrinsic mechanisms. Here, we show that the extrinsic axon guidance cues Netrins, secreted by a glial niche surrounding larval brain neural stem cell lineages, regulate NB ASCD. Netrin-Frazzled/DCC signaling modulates, through Abelson kinase, Robo1 signaling threshold levels in Drosophila larval brain neural stem and progenitor cells of NBII lineages. Unbalanced Robo1 signaling levels induce ectopic NBs and progenitor cells due to failures in the ASCD process. Mechanistically, Robo1 signaling directly impinges on the intrinsic ASCD machinery, such as aPKC, Canoe/Afadin, and Numb, through the small GTPases Rac1 and Cdc42, which are required for the localization in mitotic NBs of Par-6, a Cdc42 physical partner and a core component of the Par (Par-6-aPKC-Par3/Bazooka) apical complex.
Asunto(s)
Proteínas de Drosophila , Células-Madre Neurales , Animales , División Celular Asimétrica , Drosophila/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/fisiología , Proteínas de Unión al GTP , Hormonas Juveniles , Larva/metabolismo , Proteínas del Tejido Nervioso/genética , Netrinas , Células-Madre Neurales/metabolismo , Receptores InmunológicosRESUMEN
A connection between compromised asymmetric cell division (ACD) and tumorigenesis was proven some years ago using Drosophila larval brain neural stem cells, called neuroblasts (NBs), as a model system. Since then, we have learned that compromised ACD does not always promote tumorigenesis, as ACD is an extremely well-regulated process in which redundancy substantially overcomes potential ACD failures. Considering this, we have performed a pilot RNAi screen in Drosophila larval brain NB lineages using RasV12 scribble (scrib) mutant clones as a sensitized genetic background, in which ACD is affected but does not cause tumoral growth. First, as a proof of concept, we have tested known ACD regulators in this sensitized background, such as lethal (2) giant larvae and warts. Although the downregulation of these ACD modulators in NB clones does not induce tumorigenesis, their downregulation along with RasV12 scrib does cause tumor-like overgrowth. Based on these results, we have randomly screened 79 RNAi lines detecting 15 potential novel ACD regulators/tumor suppressor genes. We conclude that RasV12 scrib is a good sensitized genetic background in which to identify tumor suppressor genes involved in NB ACD, whose function could otherwise be masked by the high redundancy of the ACD process.
Asunto(s)
División Celular Asimétrica/genética , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Genes Supresores de Tumor/fisiología , Células-Madre Neurales/metabolismo , Animales , Regulación hacia Abajo , Proteínas de Drosophila/genética , Larva/citología , Larva/genética , Larva/metabolismo , Proteínas de la Membrana/genética , Interferencia de ARN , Proteínas ras/genética , Proteínas ras/metabolismoRESUMEN
Non-muscle myosin II molecules are actin-binding proteins with ATPase activity, this latter capacity providing the energy required for actin filament cross-linking and contraction. The activation of these molecular motors relies on direct phosphorylation at conserved sites through different protein kinases, including the Rho-associated coiled coil-containing kinase (ROCK). In the light of some recent results found in our lab, we comment on the necessity of additional regulatory mechanisms to control the subcellular distribution of non-muscle myosin II proteins to ensure their full activation.
Asunto(s)
Adenosina Trifosfatasas/metabolismo , Proteínas de Microfilamentos/metabolismo , Cadenas Pesadas de Miosina/metabolismo , Quinasas Asociadas a rho/metabolismo , Humanos , FosforilaciónRESUMEN
The Scribble polarity module is composed by Scribble (Scrib), Discs large 1 (Dlg1) and Lethal (2) giant larvae (L(2)gl), a group of highly conserved neoplastic tumor suppressor genes (TSGs) from flies to humans. Even though the Scribble module has been profusely studied in epithelial cell polarity, the number of tissues and processes in which it is involved is increasingly growing. Here we discuss the role of the Scribble module in the asymmetric division of Drosophila neuroblasts (NBs), as well as the underlying mechanisms by which those TSGs act in this process. Finally, we also describe what we know about the consequences of mutating these genes in impairing the process of asymmetric NB division and promoting tumor-like overgrowth.
Asunto(s)
División Celular Asimétrica/genética , Polaridad Celular/genética , Transformación Celular Neoplásica/genética , Proteínas de la Membrana/genética , Modelos Biológicos , Células-Madre Neurales/metabolismo , Proteínas Supresoras de Tumor/genética , Animales , Diferenciación Celular/genética , Transformación Celular Neoplásica/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster , Humanos , Proteínas de la Membrana/metabolismo , Células-Madre Neurales/patología , Neurogénesis , Transducción de Señal , Proteínas Supresoras de Tumor/metabolismoRESUMEN
The orientation of the mitotic spindle is a crucial process during development and adult tissue homeostasis and multiple mechanisms have been shown to intrinsically regulate this process. However, much less is known about the extrinsic cues involved in modulating spindle orientation. We have recently uncovered a novel function of Eph intercellular signaling in regulating spindle alignment by ultimately ensuring the correct cortical distribution of central components within the intrinsic spindle orientation machinery. Here, we comment on these results, novel questions that they open and potential additional research to address in the future.
Asunto(s)
Drosophila/crecimiento & desarrollo , Drosophila/metabolismo , Receptores de la Familia Eph/metabolismo , Transducción de Señal/fisiología , Huso Acromático/metabolismo , Animales , División Celular Asimétrica/fisiología , Carcinogénesis/metabolismo , Polaridad Celular/fisiología , Efrinas/metabolismo , Células Neuroepiteliales/metabolismo , Lóbulo Óptico de Animales no Mamíferos/citologíaRESUMEN
Mitotic spindle orientation must be tightly regulated during development and adult tissue homeostasis. It determines cell-fate specification and tissue architecture during asymmetric and symmetric cell division, respectively. Here, we uncover a novel role for Ephrin-Eph intercellular signaling in controlling mitotic spindle alignment in Drosophila optic lobe neuroepithelial cells through aPKC activity-dependent myosin II regulation. We show that conserved core components of the mitotic spindle orientation machinery, including Discs Large1, Mud/NuMA, and Canoe/Afadin, mislocalize in dividing Eph mutant neuroepithelial cells and produce spindle alignment defects in these cells when they are down-regulated. In addition, the loss of Eph leads to a Rho signaling-dependent activation of the PI3K-Akt1 pathway, enhancing cell proliferation within this neuroepithelium. Hence, Eph signaling is a novel extrinsic mechanism that regulates both spindle orientation and cell proliferation in the Drosophila optic lobe neuroepithelium. Similar mechanisms could operate in other Drosophila and vertebrate epithelia.
Asunto(s)
Polaridad Celular , Proliferación Celular , Proteínas de Drosophila/metabolismo , Proteínas de la Membrana/metabolismo , Células Neuroepiteliales/enzimología , Lóbulo Óptico de Animales no Mamíferos/enzimología , Huso Acromático/enzimología , Animales , Proteínas de Drosophila/genética , Drosophila melanogaster , Regulación del Desarrollo de la Expresión Génica , Regulación Enzimológica de la Expresión Génica , Proteínas de la Membrana/genética , Mutación , Miosina Tipo II/genética , Miosina Tipo II/metabolismo , Lóbulo Óptico de Animales no Mamíferos/citología , Fosfatidilinositol 3-Quinasa/genética , Fosfatidilinositol 3-Quinasa/metabolismo , Proteína Quinasa C/genética , Proteína Quinasa C/metabolismo , Proteínas Proto-Oncogénicas c-akt/genética , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal , Huso Acromático/genética , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismoRESUMEN
The positioning and the cleavage plane orientation of mitotic cells in pseudostratified epithelia (PSE) must be tightly regulated since failures in any of these processes might have fatal consequences during development. Here we present a simple method to determine the spindle orientation as well as the positioning of neuroepithelial mitotic cells within the Outer Proliferation Center (OPC) of Drosophila larval brains.
RESUMEN
Asymmetric cell division (ACD) is an essential process during development for generating cell diversity. In addition, a more recent connection between ACD, cancer and stem cell biology has opened novel and highly intriguing venues in the field. This connection between compromised ACD and tumorigenesis was first demonstrated using Drosophila neural stem cells (neuroblasts, NBs) more than a decade ago and, over the past years, it has also been established in vertebrate stem cells. Here, focusing on Drosophila larval brain NBs, and in light of results recently obtained in our lab, we revisit this connection emphasizing two main aspects: 1) the differences in tumor suppressor activity of different ACD regulators and 2) the potential relevance of environment and temporal window frame for compromised ACD-dependent induction of tumor-like overgrowth.
Asunto(s)
División Celular , Drosophila melanogaster/citología , Animales , Encéfalo/citología , Carcinogénesis , Drosophila melanogaster/genética , Genes Supresores de Tumor , Larva/citología , Células MadreRESUMEN
Over the past decade an intriguing connection between asymmetric cell division, stem cells and tumorigenesis has emerged. Neuroblasts, which are the neural stem cells of the Drosophila central nervous system, divide asymmetrically and constitute an excellent paradigm for investigating this connection further. Here we show that the simultaneous loss of the asymmetric cell division regulators Canoe (afadin in mammals) and Scribble in neuroblast clones leads to tumor-like overgrowth through both a severe disruption of the asymmetric cell division process and canoe loss-mediated Ras-PI3K-Akt activation. Moreover, canoe loss also interacts synergistically with scribble loss to promote overgrowth in epithelial tissues, here just by activating the Ras-Raf-MAPK pathway. discs large 1 and lethal (2) giant larvae, which are functionally related to scribble, contribute to repress the Ras-MAPK signaling cascade in epithelia. Hence, our work uncovers novel cooperative interactions between all these well-conserved tumor suppressors that ensure tight regulation of the Ras signaling pathway.
Asunto(s)
Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , IMP Deshidrogenasa/metabolismo , Proteínas de la Membrana/genética , Mutación , Células-Madre Neurales/citología , Células-Madre Neurales/metabolismo , Animales , Animales Modificados Genéticamente , Apoptosis , División Celular Asimétrica/genética , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/metabolismo , Transformación Celular Neoplásica/patología , Proteínas de Drosophila/deficiencia , Drosophila melanogaster/citología , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Células Epiteliales/citología , Células Epiteliales/metabolismo , Femenino , Técnicas de Inactivación de Genes , Genes de Insecto , IMP Deshidrogenasa/genética , Sistema de Señalización de MAP Quinasas , Masculino , Proteínas de la Membrana/deficiencia , Proteínas de la Membrana/metabolismo , Modelos Biológicos , Transducción de SeñalRESUMEN
Asymmetric cell division (ACD) is a crucial process during development, homeostasis, and cancer. Stem and progenitor cells divide asymmetrically, giving rise to two daughter cells, one of which retains the parent cell self-renewal capacity, while the other is committed to differentiation. Any imbalance in this process can induce overgrowth or even a cancer-like state. Here, we show that core components of the Hippo signaling pathway, an evolutionarily conserved organ growth regulator, modulate ACD in Drosophila. Hippo pathway inactivation disrupts the asymmetric localization of ACD regulators, leading to aberrant mitotic spindle orientation and defects in the generation of unequal-sized daughter cells. The Hippo pathway downstream kinase Warts, LATS1-2 in mammals, associates with the ACD modulators Inscuteable and Bazooka in vivo and phosphorylates Canoe, the ortholog of Afadin/AF-6, in vitro. Moreover, phosphosite mutant Canoe protein fails to form apical crescents in dividing neuroblasts in vivo, and the lack of Canoe phosphorylation by Warts leads to failures of Discs Large apical localization in metaphase neuroblasts. Given the relevance of ACD in stem cells during tissue homeostasis, and the well-documented role of the Hippo pathway as a tumor suppressor, these results represent a potential route for perturbations in the Hippo signaling to induce tumorigenesis via aberrant stem cell divisions.
Asunto(s)
División Celular Asimétrica/fisiología , Proteínas de Drosophila/metabolismo , Proteínas Quinasas/metabolismo , Animales , Proteínas Portadoras/metabolismo , Diferenciación Celular/fisiología , Polaridad Celular/fisiología , Proteínas del Citoesqueleto/metabolismo , Drosophila , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Neuronas/fisiología , Fosforilación , Proteínas Serina-Treonina Quinasas/metabolismo , Transducción de Señal , Células Madre/citologíaRESUMEN
The indusium griseum (IG), a thin layer of gray matter in contact with the dorsal surface of the corpus callosum and the lateral gray matter of the cingulate gyrus, has a common origin with hippocampus and shows similar organization with the dentate gyrus. Although some studies have examined the effect of methamphetamine (METH), an addictive and an illegal psychostimulant on this structure, quantitative effects and possible mechanism of actions of METH in this area are lacking. By applying two different protocols of equivalent METH administration (i.e., a high dose of 1 × 30 mg/kg and a lower and repeated injection dose of 3 × 10 mg/kg) and using a specific silver staining method in mice, we demonstrate that this drug produces degeneration in IG with both protocols, without affecting the dopaminergic system. Moreover, we observed quantitative increases in labeling of GFAP and Iba-1, markers of astro- and microgliosis, respectively, which suggest astrogliosis and microgliosis. Thus, our study provides morphological and semi-quantitative evidence that METH induces neurodegeneration in IG and that this damage is associated with astrogliosis and microgliosis in this area.
Asunto(s)
Gliosis/inducido químicamente , Lóbulo Límbico/efectos de los fármacos , Lóbulo Límbico/patología , Metanfetamina/toxicidad , Animales , Astrocitos/efectos de los fármacos , Astrocitos/patología , Masculino , Metanfetamina/administración & dosificación , Ratones , Ratones Endogámicos C57BL , Microglía/efectos de los fármacos , Microglía/patologíaRESUMEN
Cell polarity is inherent to the process of asymmetric cell division, which relies on the asymmetric distribution of multiple polarity proteins and cell-fate determinants in the cell cortex. The establishment and maintenance of cell polarity require the orchestration of numerous cellular processes. These include cytoplasmic movements, cytoskeleton dynamics, and different signaling events. Equally relevant is the plasma membrane composition, such as the lipid environment that endows particular membrane subdomains with specific characteristics. Sorting receptors and sorting determinants, including posttranslational modifications, also contribute to cell polarization. Together, all these mechanisms would be expected to have great relevance in the context of asymmetric cell division, an essential process in both physiological and pathological conditions.
Asunto(s)
División Celular Asimétrica/genética , Citoplasma/metabolismo , Citoesqueleto/metabolismo , Células Eucariotas/metabolismo , Procesamiento Proteico-Postraduccional , Animales , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Membrana Celular/química , Membrana Celular/metabolismo , Polaridad Celular , Citoesqueleto/genética , Citoesqueleto/ultraestructura , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Endocitosis , Células Eucariotas/citología , Exocitosis , Transporte de Proteínas , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Transducción de SeñalRESUMEN
It is firmly established that interactions between neurons and glia are fundamental across species for the correct establishment of a functional brain. Here, we found that the glia of the Drosophila larval brain display an essential non-autonomous role during the development of the optic lobe. The optic lobe develops from neuroepithelial cells that proliferate by dividing symmetrically until they switch to asymmetric/differentiative divisions that generate neuroblasts. The proneural gene lethal of scute (l'sc) is transiently activated by the epidermal growth factor receptor (EGFR)-Ras signal transduction pathway at the leading edge of a proneural wave that sweeps from medial to lateral neuroepithelium, promoting this switch. This process is tightly regulated by the tissue-autonomous function within the neuroepithelium of multiple signaling pathways, including EGFR-Ras and Notch. This study shows that the Notch ligand Serrate (Ser) is expressed in the glia and it forms a complex in vivo with Notch and Canoe, which colocalize at the adherens junctions of neuroepithelial cells. This complex is crucial for interactions between glia and neuroepithelial cells during optic lobe development. Ser is tissue-autonomously required in the glia where it activates Notch to regulate its proliferation, and non-autonomously in the neuroepithelium where Ser induces Notch signaling to avoid the premature activation of the EGFR-Ras pathway and hence of L'sc. Interestingly, different Notch activity reporters showed very different expression patterns in the glia and in the neuroepithelium, suggesting the existence of tissue-specific factors that promote the expression of particular Notch target genes or/and a reporter response dependent on different thresholds of Notch signaling.
Asunto(s)
Proteínas de Unión al Calcio/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila/metabolismo , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Proteínas de la Membrana/metabolismo , Células Neuroepiteliales/metabolismo , Neuroglía/metabolismo , Lóbulo Óptico de Animales no Mamíferos/crecimiento & desarrollo , Receptores Notch/metabolismo , Animales , Proteínas de Unión al Calcio/genética , Drosophila/genética , Drosophila/crecimiento & desarrollo , Proteínas de Drosophila/genética , Péptidos y Proteínas de Señalización Intercelular/genética , Proteína Jagged-1 , Proteínas de la Membrana/genética , Lóbulo Óptico de Animales no Mamíferos/metabolismo , Unión Proteica , Receptores Notch/genética , Proteínas Serrate-Jagged , Transducción de SeñalRESUMEN
Axon guidance is a key process during nervous system development and regeneration. One of the best established paradigms to study the mechanisms underlying this process is the axon decision of whether or not to cross the midline in the Drosophila CNS. An essential regulator of that decision is the well conserved Slit-Robo signaling pathway. Slit guidance cues act through Robo receptors to repel axons from the midline. Despite good progress in our knowledge about these proteins, the intracellular mechanisms associated with Robo function remain poorly defined. In this work, we found that the scaffolding protein Canoe (Cno), the Drosophila orthologue of AF-6/Afadin, is essential for Slit-Robo signaling. Cno is expressed along longitudinal axonal pioneer tracts, and longitudinal Robo/Fasciclin2-positive axons aberrantly cross the midline in cno mutant embryos. cno mutant primary neurons show a significant reduction of Robo localized in growth cone filopodia and Cno forms a complex with Robo in vivo. Moreover, the commissureless (comm) phenotype (i.e., lack of commissures due to constitutive surface presentation of Robo in all neurons) is suppressed in comm, cno double-mutant embryos. Specific genetic interactions between cno, slit, robo, and genes encoding other components of the Robo pathway, such as Neurexin-IV, Syndecan, and Rac GTPases, further confirm that Cno functionally interacts with the Slit-Robo pathway. Our data argue that Cno is a novel regulator of the Slit-Robo signaling pathway, crucial for regulating the subcellular localization of Robo and for transducing its signaling to the actin cytoskeleton during axon guidance at the midline.
Asunto(s)
Axones/metabolismo , Proteínas de Drosophila/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Neuronas/metabolismo , Receptores Inmunológicos/metabolismo , Transducción de Señal/fisiología , Actinas/metabolismo , Animales , Animales Modificados Genéticamente , Sistema Nervioso Central/citología , Sistema Nervioso Central/metabolismo , Quimiotaxis/fisiología , Citoesqueleto/metabolismo , Drosophila , Proteínas de Drosophila/genética , Femenino , Conos de Crecimiento/metabolismo , Masculino , Proteínas del Tejido Nervioso/genética , Neuronas/citología , Receptores Inmunológicos/genética , Proteínas RoundaboutRESUMEN
Members of the Ras superfamily of small guanosine triphosphatases (GTPases) function as key nodes within signaling networks in a remarkable range of cellular processes, including cell proliferation, differentiation, growth, cell-cell adhesion and apoptosis. We recently described a novel role for the Ras-like small GTPases Rap1 and Ral in regulating cortical polarity and spindle orientation during asymmetric neuroblast division in Drosophila. The participation of these proteins in promoting cell polarization seems to be a common theme throughout evolution.
Asunto(s)
Proteínas de Unión al GTP Monoméricas/metabolismo , Animales , Polaridad Celular , Drosophila/citología , Drosophila/metabolismo , Proteínas de Drosophila/metabolismo , Humanos , Saccharomyces cerevisiae/citología , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Transducción de Señal , Proteínas de Unión al GTP ral/metabolismo , Proteínas de Unión al GTP rap1/metabolismoRESUMEN
A crucial first step in asymmetric cell division is to establish an axis of cell polarity along which the mitotic spindle aligns. Drosophila melanogaster neural stem cells, called neuroblasts (NBs), divide asymmetrically through intrinsic polarity cues, which regulate spindle orientation and cortical polarity. In this paper, we show that the Ras-like small guanosine triphosphatase Rap1 signals through the Ral guanine nucleotide exchange factor Rgl and the PDZ protein Canoe (Cno; AF-6/Afadin in vertebrates) to modulate the NB division axis and its apicobasal cortical polarity. Rap1 is slightly enriched at the apical pole of metaphase/anaphase NBs and was found in a complex with atypical protein kinase C and Par6 in vivo. Loss of function and gain of function of Rap1, Rgl, and Ral proteins disrupt the mitotic axis orientation, the localization of Cno and Mushroom body defect, and the localization of cell fate determinants. We propose that the Rap1-Rgl-Ral signaling network is a novel mechanism that cooperates with other intrinsic polarity cues to modulate asymmetric NB division.
Asunto(s)
Polaridad Celular/fisiología , Drosophila melanogaster/citología , Células-Madre Neurales/citología , Huso Acromático/metabolismo , Proteínas de Unión al GTP ral/metabolismo , Factor de Intercambio de Guanina Nucleótido ral/metabolismo , Proteínas de Unión al GTP rap1/metabolismo , Animales , Drosophila melanogaster/metabolismo , Femenino , Masculino , Células-Madre Neurales/metabolismo , Transducción de SeñalRESUMEN
Vertebrates and insects alike use glial cells as intermediate targets to guide growing axons. Similar to vertebrate oligodendrocytes, Drosophila midline glia ensheath and separate axonal commissures. Neuron-glia interactions are crucial during these events, although the proteins involved remain largely unknown. Here, we show that Canoe (Cno), the Drosophila ortholog of AF-6, and the DE-cadherin Shotgun (Shg) are highly restricted to the interface between midline glia and commissural axons. cno mutant analysis, genetic interactions and co-immunoprecipitation assays unveil Cno function as a novel regulator of neuron-glia interactions, forming a complex with Shg, Wrapper and Neurexin IV, the homolog of vertebrate Caspr/paranodin. Our results also support additional functions of Cno, independent of adherens junctions, as a regulator of adhesion and signaling events in non-epithelial tissues.
Asunto(s)
Cadherinas/metabolismo , Moléculas de Adhesión Celular Neuronal/metabolismo , Sistema Nervioso Central/metabolismo , Proteínas de Drosophila/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Neuroglía/metabolismo , Neuronas/metabolismo , Animales , Sistema Nervioso Central/citología , Drosophila , Proteínas de Drosophila/genética , Técnica del Anticuerpo Fluorescente , Inmunohistoquímica , Inmunoprecipitación , Unión ProteicaRESUMEN
The past decade has witnessed an explosion in the growth of proteomics. The completion of numerous genome sequences, the development of powerful protein analytical technologies, as well as the design of innovative bioinformatics tools have marked the beginning of a new post-genomic era. Proteomics, the large-scale analysis of proteins in an organism, organ or organelle encompasses different aspects: (1) the identification, analysis of post-translational modifications and quantification of proteins; (2) the study of protein-protein interactions; and (3) the functional analysis of interactome networks. Here, we briefly summarize the emerging analytical tools and databases that are paving the way for studying Drosophila development by proteomic approaches.
Asunto(s)
Bases de Datos de Proteínas , Drosophila/crecimiento & desarrollo , Proteómica , Animales , Proteínas de Drosophila/metabolismo , Unión Proteica , Procesamiento Proteico-PostraduccionalRESUMEN
Remarkable progress in genetics and molecular biology has made possible the sequencing of the genomes from numerous species. In the post-genomic era, technical developments in the fields of proteomics and bioinformatics are poised to further catapult our understanding of protein structure, function and organization into complex signaling networks. One of the greatest challenges in the field now is to unravel the functional signaling networks and their spatio-temporal regulation in living cells. Here, the need for such in vivo system-wide level approach is illustrated in relation to the mechanisms that underlie the biological process of asymmetric cell division. Genomic, post-genomic and live imaging techniques are reviewed in light of the huge impact they are having on this field for the discovering of new proteins and for the in vivo analysis of asymmetric cell division. The proteins, signals and the emerging networking of functional connections that is arising between them during this process in the Drosophila nervous system will be also discussed.
Asunto(s)
División Celular , Drosophila melanogaster/citología , Drosophila melanogaster/embriología , Transducción de Señal , Animales , Sistema Nervioso/citología , Sistema Nervioso/embriologíaRESUMEN
Asymmetric cell division is a conserved mechanism to generate cellular diversity during animal development and a key process in cancer and stem cell biology. Despite the increasing number of proteins characterized, the complex network of proteins interactions established during asymmetric cell division is still poorly understood. This suggests that additional components must be contributing to orchestrate all the events underlying this tightly modulated process. The PDZ protein Canoe (Cno) and its mammalian counterparts AF-6 and Afadin are critical to regulate intracellular signaling and to organize cell junctions throughout development. Here, we show that Cno functions as a new effector of the apical proteins Inscuteable (Insc)-Partner of Inscuteable (Pins)-Galphai during the asymmetric division of Drosophila neuroblasts (NBs). Cno localizes apically in metaphase NBs and coimmunoprecipitates with Pins in vivo. Furthermore, Cno functionally interacts with the apical proteins Insc, Galphai, and Mushroom body defect (Mud) to generate correct neuronal lineages. Failures in muscle and heart lineages are also detected in cno mutant embryos. Our results strongly support a new function for Cno regulating key processes during asymmetric NB division: the localization of cell-fate determinants, the orientation of the mitotic spindle, and the generation of unequal-sized daughter cells.