RESUMEN
Aggressive neoplastic growth can be initiated by a limited number of genetic alterations, such as the well-established cooperation between loss of cell architecture and hyperactive signaling pathways. However, our understanding of how these different alterations interact and influence each other remains very incomplete. Using Drosophila paradigms of imaginal wing disc epithelial growth, we have monitored the changes in Notch pathway activity according to the polarity status of cells (scrib mutant). We show that the scrib mutation impacts the direct transcriptional output of the Notch pathway, without altering the global distribution of Su(H), the Notch-dedicated transcription factor. The Notch-dependent neoplasms require, however, the action of a group of transcription factors, similar to those previously identified for Ras/scrib neoplasm (namely AP-1, Stat92E, Ftz-F1 and basic leucine zipper factors), further suggesting the importance of this transcription factor network during neoplastic growth. Finally, our work highlights some Notch/scrib specificities, in particular the role of the PAR domain-containing basic leucine zipper transcription factor and Notch direct target Pdp1 for neoplastic growth.
Asunto(s)
Proteínas de Drosophila/metabolismo , Drosophila/metabolismo , Receptores Notch/metabolismo , Animales , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/antagonistas & inhibidores , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/genética , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/metabolismo , Carcinogénesis , Drosophila/crecimiento & desarrollo , Proteínas de Drosophila/antagonistas & inhibidores , Proteínas de Drosophila/genética , Células Epiteliales/citología , Células Epiteliales/metabolismo , Larva/metabolismo , Proteínas de la Membrana/antagonistas & inhibidores , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Mutación , Neoplasias/metabolismo , Neoplasias/patología , Interferencia de ARN , Transducción de Señal , Alas de Animales/metabolismoRESUMEN
Differentiating left and right hand sides during embryogenesis represents a major event in body patterning. Left-Right (L/R) asymmetry in bilateria is essential for handed positioning, morphogenesis and ultimately the function of organs (including the brain), with defective L/R asymmetry leading to severe pathologies in human. How and when symmetry is initially broken during embryogenesis remains debated and is a major focus in the field. Work done over the past 20 years, in both vertebrate and invertebrate models, has revealed a number of distinct pathways and mechanisms important for establishing L/R asymmetry and for spreading it to tissues and organs. In this review, we summarize our current knowledge and discuss the diversity of L/R patterning from cells to organs during evolution.
Asunto(s)
Evolución Biológica , Tipificación del Cuerpo , Desarrollo Embrionario/genética , Animales , Humanos , Invertebrados/genética , Vertebrados/genéticaRESUMEN
In bilateria, positioning and looping of visceral organs requires proper left-right (L/R) asymmetry establishment. Recent work in Drosophila has identified a novel situs inversus gene encoding the unconventional type ID myosin (MyoID). In myoID mutant flies, the L/R axis is inverted, causing reversed looping of organs, such as the gut, spermiduct and genitalia. We have previously shown that MyoID interacts physically with ß-Catenin, suggesting a role of the adherens junction in Drosophila L/R asymmetry. Here, we show that DE-Cadherin co-immunoprecipitates with MyoID and is required for MyoID L/R activity. We further demonstrate that MyoIC, a closely related unconventional type I myosin, can antagonize MyoID L/R activity by preventing its binding to adherens junction components, both in vitro and in vivo. Interestingly, DE-Cadherin inhibits MyoIC, providing a protective mechanism to MyoID function. Conditional genetic experiments indicate that DE-Cadherin, MyoIC and MyoID show temporal synchronicity for their function in L/R asymmetry. These data suggest that following MyoID recruitment by ß-Catenin at the adherens junction, DE-Cadherin has a twofold effect on Drosophila L/R asymmetry by promoting MyoID activity and repressing that of MyoIC. Interestingly, the product of the vertebrate situs inversus gene inversin also physically interacts with ß-Catenin, suggesting that the adherens junction might serve as a conserved platform for determinants to establish L/R asymmetry both in vertebrates and invertebrates.
Asunto(s)
Tipificación del Cuerpo/fisiología , Cadherinas/metabolismo , Proteínas de Drosophila/metabolismo , Miosinas/metabolismo , Animales , Tipificación del Cuerpo/genética , Cadherinas/genética , Drosophila , Proteínas de Drosophila/genética , Inmunoprecipitación , Miosina Tipo I/genética , Miosina Tipo I/metabolismo , Miosinas/genética , Unión Proteica , beta Catenina/genética , beta Catenina/metabolismoRESUMEN
Drosophila is a classical model to study body patterning, however left-right (L/R) asymmetry had remained unexplored, until recently. The discovery of the conserved myosin ID gene as a major determinant of L/R asymmetry has revealed a novel L/R pathway involving the actin cytoskeleton and the adherens junction. In this process, the HOX gene Abdominal-B plays a major role through the control of myosin ID expression and therefore symmetry breaking. In this review, we present organs and markers showing L/R asymmetry in Drosophila and discuss our current understanding of the underlying molecular genetic mechanisms. Drosophila represents a valuable model system revealing novel strategies to establish L/R asymmetry in invertebrates and providing an evolutionary perspective to the problem of laterality in bilateria.
Asunto(s)
Tipificación del Cuerpo/fisiología , Drosophila/genética , Drosophila/metabolismo , Miosina Tipo I/genética , Miosina Tipo I/metabolismo , Transducción de Señal , Animales , Regulación de la Expresión Génica , Morfogénesis/fisiologíaRESUMEN
In metazoans, factors of the insulin family control growth, metabolism, longevity, and fertility in response to environmental cues. In Drosophila, a family of seven insulin-like peptides, called Dilps, activate a common insulin receptor. Some Dilp peptides carry both metabolic and growth functions, raising the possibility that various binding partners specify their functions. Here we identify dALS, the fly ortholog of the vertebrate insulin-like growth factor (IGF)-binding protein acid-labile subunit (ALS), as a Dilp partner that forms a circulating trimeric complex with one molecule of Dilp and one molecule of Imp-L2, an IgG-family molecule distantly related to mammalian IGF-binding proteins (IGFBPs). We further show that dALS antagonizes Dilp function to control animal growth as well as carbohydrate and fat metabolism. These results lead us to propose an evolutionary perspective in which ALS function appeared prior to the separation between metabolic and growth effects that are associated with vertebrate insulin and IGFs.
Asunto(s)
Proteínas de Drosophila/metabolismo , Drosophila/crecimiento & desarrollo , Drosophila/metabolismo , Proteínas de Unión a Factor de Crecimiento Similar a la Insulina/metabolismo , Somatomedinas/metabolismo , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Western Blotting , Proteínas de Drosophila/genética , Metabolismo Energético , Regulación de la Expresión Génica , Proteínas de Unión a Factor de Crecimiento Similar a la Insulina/genética , Larva/crecimiento & desarrollo , Larva/metabolismo , Complejos Multiproteicos/química , Complejos Multiproteicos/metabolismo , Estrés FisiológicoRESUMEN
Alterations to cell polarization or to intercellular junctions are often associated with epithelial cancer progression, including breast cancers (BCa). We show here that the loss of the junctional scaffold protein MAGI1 is associated with bad prognosis in luminal BCa, and promotes tumorigenesis. E-cadherin and the actin binding scaffold AMOTL2 accumulate in MAGI1 deficient cells which are subjected to increased stiffness. These alterations are associated with low YAP activity, the terminal Hippo-pathway effector, but with an elevated ROCK and p38 Stress Activated Protein Kinase activities. Blocking ROCK prevented p38 activation, suggesting that MAGI1 limits p38 activity in part through releasing actin strength. Importantly, the increased tumorigenicity of MAGI1 deficient cells is rescued in the absence of AMOTL2 or after inhibition of p38, demonstrating that MAGI1 acts as a tumor-suppressor in luminal BCa by inhibiting an AMOTL2/p38 stress pathway.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Angiomotinas/metabolismo , Neoplasias de la Mama/prevención & control , Carcinogénesis/patología , Moléculas de Adhesión Celular/metabolismo , Guanilato-Quinasas/metabolismo , Transducción de Señal , Estrés Fisiológico , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismo , Proteínas Adaptadoras Transductoras de Señales/deficiencia , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Cadherinas/metabolismo , Carcinogénesis/metabolismo , Moléculas de Adhesión Celular/deficiencia , Línea Celular Tumoral , Proliferación Celular , Células Epiteliales/metabolismo , Células Epiteliales/patología , Femenino , Guanilato-Quinasas/deficiencia , Humanos , Fenotipo , Unión Proteica , Proteínas Señalizadoras YAP/metabolismo , beta Catenina/metabolismo , Quinasas Asociadas a rho/metabolismoRESUMEN
The establishment of left-right (LR) asymmetry is fundamental to animal development, but the identification of a unifying mechanism establishing laterality across different phyla has remained elusive. A cilia-driven, directional fluid flow is important for symmetry breaking in numerous vertebrates, including zebrafish. Alternatively, LR asymmetry can be established independently of cilia, notably through the intrinsic chirality of the acto-myosin cytoskeleton. Here, we show that Myosin1D (Myo1D), a previously identified regulator of Drosophila LR asymmetry, is essential for the formation and function of the zebrafish LR organizer (LRO), Kupffer's vesicle (KV). Myo1D controls the orientation of LRO cilia and interacts functionally with the planar cell polarity (PCP) pathway component VanGogh-like2 (Vangl2), to shape a productive LRO flow. Our findings identify Myo1D as an evolutionarily conserved regulator of animal LR asymmetry, and show that functional interactions between Myo1D and PCP are central to the establishment of animal LR asymmetry.
Asunto(s)
Tipificación del Cuerpo/genética , Miosinas/genética , Proteínas de Pez Cebra/genética , Pez Cebra/genética , Animales , Animales Modificados Genéticamente , Polaridad Celular/genética , Cilios/genética , Cilios/metabolismo , Embrión no Mamífero/embriología , Embrión no Mamífero/metabolismo , Regulación del Desarrollo de la Expresión Génica , Factores de Determinación Derecha-Izquierda/genética , Factores de Determinación Derecha-Izquierda/metabolismo , Mutación , Miosinas/metabolismo , Pez Cebra/embriología , Pez Cebra/metabolismo , Proteínas de Pez Cebra/metabolismoRESUMEN
During development, cell numbers are tightly regulated, ensuring that tissues and organs reach their correct size and shape. Recent evidence has highlighted the intricate connections between the cytoskeleton and the regulation of the key growth control Hippo pathway. Looking for apical scaffolds regulating tissue growth, we describe that Drosophila melanogaster big bang (Bbg), a poorly characterized multi-PDZ scaffold, controls epithelial tissue growth without affecting epithelial polarity and architecture. bbg-mutant tissues are smaller, with fewer cells that are less apically constricted than normal. We show that Bbg binds to and colocalizes tightly with the ß-heavy-Spectrin/Kst subunit at the apical cortex and promotes Yki activity, F-actin enrichment, and the phosphorylation of the myosin II regulatory light chain Spaghetti squash. We propose a model in which the spectrin cytoskeleton recruits Bbg to the cortex, where Bbg promotes actomyosin contractility to regulate epithelial tissue growth.
Asunto(s)
Proteínas de Drosophila/metabolismo , Discos Imaginales/embriología , Modelos Biológicos , Mutación , Alas de Animales/embriología , Animales , Proteínas de Drosophila/genética , Drosophila melanogaster , Discos Imaginales/citología , Alas de Animales/citologíaRESUMEN
Left-right (LR) asymmetry is essential for organ development and function in metazoans, but how initial LR cue is relayed to tissues still remains unclear. Here, we propose a mechanism by which the Drosophila LR determinant Myosin ID (MyoID) transfers LR information to neighboring cells through the planar cell polarity (PCP) atypical cadherin Dachsous (Ds). Molecular interaction between MyoID and Ds in a specific LR organizer controls dextral cell polarity of adjoining hindgut progenitors and is required for organ looping in adults. Loss of Ds blocks hindgut tissue polarization and looping, indicating that Ds is a crucial factor for both LR cue transmission and asymmetric morphogenesis. We further show that the Ds/Fat and Frizzled PCP pathways are required for the spreading of LR asymmetry throughout the hindgut progenitor tissue. These results identify a direct functional coupling between the LR determinant MyoID and PCP, essential for non-autonomous propagation of early LR asymmetry.
Asunto(s)
Tipificación del Cuerpo/fisiología , Cadherinas/fisiología , Sistema Digestivo/crecimiento & desarrollo , Proteínas de Drosophila/fisiología , Drosophila melanogaster/crecimiento & desarrollo , Drosophila melanogaster/fisiología , Animales , Animales Modificados Genéticamente , Tipificación del Cuerpo/genética , Cadherinas/genética , Polaridad Celular/genética , Polaridad Celular/fisiología , Sistema Digestivo/citología , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Regulación del Desarrollo de la Expresión Génica , Técnicas de Silenciamiento del Gen , Genes de Insecto , Modelos Biológicos , Miosinas/genética , Miosinas/fisiologíaRESUMEN
During the differentiation of erythroid cells, a vast program of maturation takes place, leading to decay or elimination of organelles, including the nucleus, mitochondria, ribosomes, lysosomes, endoplasmic reticulum and Golgi apparatus. During the last step of red cell maturation, remaining organelles, primarily mitochondria and ribosomes but also vestiges of others are finally cleared from the cell. This cleaning session also affects specific proteins that are partially or entirely removed from the cell surface. The interplay of the various events and their causal relationships are approached here.
Asunto(s)
Mitocondrias/metabolismo , Reticulocitos/metabolismo , Adenosina Trifosfato/metabolismo , Araquidonato 15-Lipooxigenasa/metabolismo , Caspasas/metabolismo , Membrana Celular/metabolismo , Activación Enzimática , Aparato de Golgi/metabolismo , Modelos Biológicos , Proteínas/metabolismo , Especies Reactivas de Oxígeno , Receptores de Transferrina/metabolismo , Relación Estructura-Actividad , TemperaturaRESUMEN
In Drosophila, left/right (LR) asymmetry is apparent in the directional looping of the gut and male genitalia. The dextral orientation of the organs depends on the activity of a single gene, MyosinID (myoID), whose mutation leads to a fully inverted LR axis, thus revealing the activity of a recessive sinistral pathway. Here, we present the identification of the Hox gene Abdominal-B (Abd-B) as an upstream regulator of LR determination. This role appears distinct from its function in anteroposterior patterning. We show that the Abd-Bm isoform binds to regulatory sequences of myoID and controls MyoID expression in the organ LR organizer. Abd-Bm is also required for the sinistral pathway. Thus, when Abd-B activity is missing, no symmetry breaking occurs and flies develop symmetrically. These findings identify the Hox gene Abd-B as directing the earliest events of LR asymmetry establishment in Drosophila.
Asunto(s)
Tipificación del Cuerpo , Anomalías del Sistema Digestivo/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/crecimiento & desarrollo , Tracto Gastrointestinal/metabolismo , Gónadas/metabolismo , Proteínas de Homeodominio/metabolismo , Miosina Tipo I/metabolismo , Animales , Anomalías del Sistema Digestivo/embriología , Proteínas de Drosophila/genética , Drosophila melanogaster/metabolismo , Tracto Gastrointestinal/anomalías , Tracto Gastrointestinal/embriología , Gónadas/anomalías , Gónadas/embriología , Proteínas de Homeodominio/genética , Técnicas para Inmunoenzimas , Masculino , Miosina Tipo I/genética , Isoformas de ProteínasRESUMEN
Insulin-like peptides (ILPs) couple growth, metabolism, longevity, and fertility with changes in nutritional availability. In Drosophila, several ILPs called Dilps are produced by the brain insulin-producing cells (IPCs), from which they are released into the hemolymph and act systemically. We show here that in response to nutrient deprivation, brain Dilps are no longer secreted and accumulate in the IPCs. We further demonstrate that the larval fat body, a functional homolog of vertebrate liver and white fat, couples the level of circulating Dilps with dietary amino acid levels by remotely controlling Dilp release through a TOR/RAPTOR-dependent mechanism. We finally use ex vivo tissue coculture to demonstrate that a humoral signal emitted by the fat body transits through the hemolymph and activates Dilp secretion in the IPCs. Thus, the availability of nutrients is remotely sensed in fat body cells and conveyed to the brain IPCs by a humoral signal controlling ILP release.
Asunto(s)
Adipocitos/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Insulina/metabolismo , Neuropéptidos/metabolismo , Animales , Encéfalo/metabolismo , Secreción de Insulina , Células Secretoras de Insulina/metabolismo , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Larva/metabolismoRESUMEN
Reticulocyte maturation into erythrocytes is the final step of erythropoiesis that occurs in the blood circulation. This terminal differentiation period corresponds to a cellular remodeling phase following expulsion of the nucleus into the bone marrow. Among other events, this remodeling leads to the disappearance of intracellular organelles and acquisition of the typical cellular biconcave form. Here, we propose that exosome biogenesis and secretion, which contributes to net loss of the cell surface membrane via selective vesicular membrane secretion, is also closely interconnected with upstream (nucleus expulsion), accompanying (mitoptosis) and downstream (vesicle clearance) events.
Asunto(s)
Diferenciación Celular , Vesículas Citoplasmáticas/fisiología , Reticulocitos/metabolismo , Animales , Vesículas Citoplasmáticas/inmunología , Vesículas Citoplasmáticas/metabolismo , Eritropoyesis , Humanos , Proteínas de la Membrana/metabolismo , Fagocitosis , Reticulocitos/citologíaRESUMEN
Reticulocytes release small membrane vesicles termed exosomes during their maturation in erythrocytes. The transferrin receptor (TfR) is completely lost from the red cell surface by its segregation in the secreted vesicles where it interacts with the heat shock cognate 70 kDa protein (hsc70). We have now determined a region of the TfR that can potentially interact with hsc70. The peptide P1 (YTRFSLARQV) from the TfR cytosolic domain: (i). binds to hsc70 (ii). with an increased affinity in oxidative conditions, (iii). competes for binding of an unfolded protein to hsc70, and (iv). inhibits the interaction of hsc70 with a recombinant protein corresponding to the cytosolic domain of the receptor. This peptide encompasses the internalization motif (YTRF) of the receptor, and accordingly an affinity column made with the immobilized peptide retains hsc70 and also the AP2 adaptor complex. On the other hand, we show that AP2 is degraded by the proteasome system during reticulocyte maturation and that the presence of the proteasome inhibitor during in vitro red cell maturation inhibits AP2 degradation and specifically decreases TfR secretion via exosomes. Finally, coimmunoprecipitation of Alix with the exosomal TfR, and binding of P1 peptide to the Alix homolog PalA suggest that Alix also interacts with the YTRF motif and contributes to exosomal TfR sorting.
Asunto(s)
Complejo 2 de Proteína Adaptadora/metabolismo , Proteínas de Unión al Calcio/metabolismo , Proteínas Portadoras/metabolismo , Exocitosis , Proteínas HSP70 de Choque Térmico/metabolismo , Receptores de Transferrina/metabolismo , Reticulocitos/citología , Reticulocitos/metabolismo , Subunidades alfa de Complejo de Proteína Adaptadora/metabolismo , Secuencia de Aminoácidos , Animales , Sitios de Unión , Biotinilación , Cromatografía de Afinidad , Dimerización , Eritrocitos/citología , Eritrocitos/metabolismo , Proteínas del Choque Térmico HSC70 , Proteínas HSP70 de Choque Térmico/genética , Humanos , Leupeptinas/farmacología , Datos de Secuencia Molecular , Fragmentos de Péptidos/química , Fragmentos de Péptidos/metabolismo , Unión Proteica , Procesamiento Proteico-Postraduccional , Ratas , Receptores de Transferrina/química , TemperaturaRESUMEN
Multivesicular bodies contain membrane vesicles which either undergo lysosomal digestion or are released in the extracellular environment as exosomes. Evidence is accumulating that supports a physiological role for exosomes in, for example, antigen presentation or removal of transferrin receptor during reticulocyte development. Here, inspired by observations on exosomal release from reticulocytes, we discuss the potential involvement of the so-called ESCRT mechanism in the entrapment of both lysosomal and exosomal cargo within the intralumenal vesicles of multivesicular bodies. We propose that this mechanism operates at different sites in the endocytic itinerary in different cells, thereby providing a tool for directional sorting. We also explore the possibility that the efficiency of sorting of molecules into exosomes increases when the recycling kinetics of molecules decreases, exosomal sorting being favored by intermolecular interactions occurring within lipid domains, or with protein webs, that slow lateral mobility. These considerations are mirrored in the context of current knowledge on the mechanism of protein sorting for degradation in lysosomes, and the hijacking of such mechanisms by some retroviruses for particle budding.
Asunto(s)
Exocitosis , Reticulocitos/citología , Secuencias de Aminoácidos , Animales , Transporte Biológico , Endocitosis , Endosomas/metabolismo , Humanos , Cinética , Lisosomas/metabolismo , Microdominios de Membrana/metabolismo , Modelos Biológicos , Estructura Terciaria de Proteína , Transporte de ProteínasRESUMEN
A subcellular fractionation procedure was developed to isolate the different endosomal compartments present during reticulocyte maturation. After reticulocyte lysis and removal of excess haemoglobin by gel chromatography, membrane vesicles were separated over a discontinuous sucrose gradient (10-40%). Two fractions were isolated: P1 at the 25-35% sucrose interface and P2 at the 17-25% sucrose interface. These fractions were morphologically characterized by electron microscopy and the distribution of endocytic markers in the fractions was detected by Western blot. Moreover, this fractionation technique was used to study the effect of 3-methyladenine (3-MA), an autophagy inhibitor, on reticulocyte maturation. The presence of 3-MA during in vitro maturation of reticulocytes induced a decrease in exosome secretion, as measured by the amount of transferrin receptor (TfR) released in the extracellular medium. The subcellular fractionation results suggested that multivesicular endosome formation from early endosomes is the step affected by 3-MA.
Asunto(s)
Adenina/análogos & derivados , Compartimento Celular/fisiología , Diferenciación Celular/fisiología , Fraccionamiento Celular , Endosomas/metabolismo , Reticulocitos/metabolismo , Adenina/farmacología , Animales , Autofagia/efectos de los fármacos , Autofagia/fisiología , Western Blotting , Compartimento Celular/efectos de los fármacos , Diferenciación Celular/efectos de los fármacos , Endosomas/efectos de los fármacos , Endosomas/ultraestructura , Espacio Extracelular/efectos de los fármacos , Espacio Extracelular/metabolismo , Proteínas HSP70 de Choque Térmico/efectos de los fármacos , Proteínas HSP70 de Choque Térmico/metabolismo , Microscopía Electrónica , Ratas , Ratas Sprague-Dawley , Receptores de Transferrina/efectos de los fármacos , Receptores de Transferrina/metabolismo , Reticulocitos/efectos de los fármacos , Reticulocitos/ultraestructura , Vesículas Secretoras/efectos de los fármacos , Vesículas Secretoras/metabolismo , Vesículas Secretoras/ultraestructura , Fracciones Subcelulares/metabolismo , Fracciones Subcelulares/ultraestructura , Proteínas de Unión al GTP rab5/efectos de los fármacos , Proteínas de Unión al GTP rab5/metabolismoRESUMEN
Exosomes are small membrane vesicles secreted by cells upon fusion of multivesicular endosomes with the cell surface. The mechanisms underlying the specific sorting of proteins in exosomal membranes are far from being unraveled. We demonstrate here, using different cells, that some molecules are released in the extracellular medium via their association with lipid raft domains of the exosomal membrane. Various typical raft-associated molecules could be detected by immunoblot in exosomes and Triton X-100-insoluble fractions isolated from exosomes of different origins. Partial localization of major histocompatibility complex (MHC) class II molecules with detergent-resistant fractions isolated from Daudi-secreted exosomes was demonstrated by immunoblot and confirmed by electron microscopy colocalization of MHC class II molecules and ganglioside GM1. Moreover, we found that exosome-associated Lyn (1) had a lower molecular weight compared with Lyn detected in cell-isolated detergent-resistant domains, (2) was absent from the Triton X-100-insoluble fraction isolated from exosomes, and (3) had lost its partitioning capacity in Triton X-114. Exosomal Lyn is probably cleaved by a caspase-3-like activity contained in secreted vesicles. All together, the data highlight the presence of lipid microdomains in exosomal membranes and suggest their participation in vesicle formation and structure, as well as the direct implication of exosomes in regulatory mechanisms.
Asunto(s)
Microdominios de Membrana/metabolismo , Proteínas de la Membrana/metabolismo , Reticulocitos/metabolismo , Animales , Transporte Biológico , Proteínas Sanguíneas/metabolismo , Caspasa 3 , Caspasas/metabolismo , Centrifugación por Gradiente de Densidad , Detergentes/farmacología , Endosomas/fisiología , Gangliósido G(M1)/metabolismo , Antígenos de Histocompatibilidad Clase II/metabolismo , Humanos , Células K562/citología , Células K562/metabolismo , Fusión de Membrana , Microdominios de Membrana/efectos de los fármacos , Octoxinol/farmacología , Polietilenglicoles/farmacología , Ratas , Ratas Sprague-Dawley , Reticulocitos/citología , Células Tumorales Cultivadas/citología , Células Tumorales Cultivadas/metabolismo , Familia-src Quinasas/metabolismoRESUMEN
During the differentiation of erythroid cells, a vast program of maturation takes place, leading to decay or elimination of organelles, including the nucleus, mitochondria, ribosomes, lysosomes, endoplasmic reticulum and Golgi apparatus. During the last step of red cell maturation, remaining organelles, primarily mitochondria and ribosomes but also vestiges of others are finally cleared from the cell. This cleaning session also affects specific proteins that are partially or entirely removed from the cell surface. The interplay of the various events and their causal relationships are approached here.