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2.
Blood ; 116(19): 4025-33, 2010 Nov 11.
Artículo en Inglés | MEDLINE | ID: mdl-20705756

RESUMEN

Sprouting of developing blood vessels is mediated by specialized motile endothelial cells localized at the tips of growing capillaries. Following behind the tip cells, endothelial stalk cells form the capillary lumen and proliferate. Expression of the Notch ligand Delta-like-4 (Dll4) in tip cells suppresses tip cell fate in neighboring stalk cells via Notch signaling. In DLL4(+/-) mouse mutants, most retinal endothelial cells display morphologic features of tip cells. We hypothesized that these mouse mutants could be used to isolate tip cells and so to determine their genetic repertoire. Using transcriptome analysis of retinal endothelial cells isolated from DLL4(+/-) and wild-type mice, we identified 3 clusters of tip cell-enriched genes, encoding extracellular matrix degrading enzymes, basement membrane components, and secreted molecules. Secreted molecules endothelial-specific molecule 1, angiopoietin 2, and apelin bind to cognate receptors on endothelial stalk cells. Knockout mice and zebrafish morpholino knockdown of apelin showed delayed angiogenesis and reduced proliferation of stalk cells expressing the apelin receptor APJ. Thus, tip cells may regulate angiogenesis via matrix remodeling, production of basement membrane, and release of secreted molecules, some of which regulate stalk cell behavior.


Asunto(s)
Células Endoteliales/metabolismo , Neovascularización Fisiológica/genética , Proteínas Adaptadoras Transductoras de Señales , Adipoquinas , Animales , Apelina , Receptores de Apelina , Proteínas de Unión al Calcio , Capilares/citología , Capilares/crecimiento & desarrollo , Capilares/metabolismo , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Células Endoteliales/citología , Células Endoteliales/efectos de los fármacos , Matriz Extracelular/metabolismo , Perfilación de la Expresión Génica , Haploinsuficiencia , Péptidos y Proteínas de Señalización Intercelular , Péptidos y Proteínas de Señalización Intracelular/deficiencia , Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Proteínas de la Membrana/deficiencia , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Familia de Multigenes , Análisis de Secuencia por Matrices de Oligonucleótidos , Receptores Acoplados a Proteínas G/deficiencia , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Vasos Retinianos/citología , Vasos Retinianos/crecimiento & desarrollo , Vasos Retinianos/metabolismo , Transducción de Señal , Serina-Treonina Quinasas TOR/metabolismo , Factor A de Crecimiento Endotelial Vascular/farmacología , Pez Cebra
3.
Nature ; 432(7014): 179-86, 2004 Nov 11.
Artículo en Inglés | MEDLINE | ID: mdl-15510105

RESUMEN

Blood vessels and nerves are complex, branched structures that share a high degree of anatomical similarity. Guidance of vessels and nerves has to be exquisitely regulated to ensure proper wiring of both systems. Several regulators of axon guidance have been identified and some of these are also expressed in endothelial cells; however, the extent to which their guidance functions are conserved in the vascular system is still incompletely understood. We show here that the repulsive netrin receptor UNC5B is expressed by endothelial tip cells of the vascular system. Disruption of the Unc5b gene in mice, or of Unc5b or netrin-1a in zebrafish, leads to aberrant extension of endothelial tip cell filopodia, excessive vessel branching and abnormal navigation. Netrin-1 causes endothelial filopodial retraction, but only when UNC5B is present. Thus, UNC5B functions as a repulsive netrin receptor in endothelial cells controlling morphogenesis of the vascular system.


Asunto(s)
Vasos Sanguíneos/embriología , Vasos Sanguíneos/metabolismo , Morfogénesis , Receptores de Superficie Celular/metabolismo , Animales , Vasos Sanguíneos/anomalías , Vasos Sanguíneos/citología , Movimiento Celular/efectos de los fármacos , Tamaño de la Célula/efectos de los fármacos , Células Endoteliales/citología , Células Endoteliales/efectos de los fármacos , Células Endoteliales/metabolismo , Endotelio Vascular/citología , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/metabolismo , Ratones , Datos de Secuencia Molecular , Mutación/genética , Factores de Crecimiento Nervioso/genética , Factores de Crecimiento Nervioso/metabolismo , Factores de Crecimiento Nervioso/farmacología , Receptores de Netrina , Netrina-1 , Seudópodos/efectos de los fármacos , Seudópodos/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Receptores de Superficie Celular/genética , Proteínas Supresoras de Tumor , Pez Cebra/embriología , Pez Cebra/genética , Pez Cebra/metabolismo , Proteínas de Pez Cebra
4.
Nat Neurosci ; 9(3): 340-8, 2006 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-16462734

RESUMEN

Vascular endothelial growth factor C (VEGF-C) was first identified as a regulator of the vascular system, where it is required for the development of lymphatic vessels. Here we report actions of VEGF-C in the central nervous system. We detected the expression of the VEGF-C receptor VEGFR-3 in neural progenitor cells in Xenopus laevis and mouse embryos. In Xenopus tadpole VEGF-C knockdowns and in mice lacking Vegfc, the proliferation of neural progenitors expressing VEGFR-3 was severely reduced, in the absence of intracerebral blood vessel defects. In addition, Vegfc-deficient mouse embryos showed a selective loss of oligodendrocyte precursor cells (OPCs) in the embryonic optic nerve. In vitro, VEGF-C stimulated the proliferation of OPCs expressing VEGFR-3 and nestin-positive ventricular neural cells. VEGF-C thus has a new, evolutionary conserved function as a growth factor selectively required by neural progenitor cells expressing its receptor VEGFR-3.


Asunto(s)
Encéfalo/embriología , Diferenciación Celular/fisiología , Factores de Crecimiento Nervioso/metabolismo , Neuronas/metabolismo , Células Madre/metabolismo , Factor C de Crecimiento Endotelial Vascular/metabolismo , Animales , Encéfalo/citología , Encéfalo/metabolismo , Células Cultivadas , Evolución Molecular , Proteínas de Filamentos Intermediarios/metabolismo , Larva , Ventrículos Laterales/citología , Ventrículos Laterales/embriología , Ventrículos Laterales/metabolismo , Ratones , Ratones Noqueados , Ratones Transgénicos , Proteínas del Tejido Nervioso/metabolismo , Nestina , Neuronas/citología , Oligodendroglía/citología , Oligodendroglía/metabolismo , Nervio Óptico/citología , Nervio Óptico/embriología , Nervio Óptico/metabolismo , Ratas , Ratas Wistar , Células Madre/citología , Factor C de Crecimiento Endotelial Vascular/genética , Receptor 3 de Factores de Crecimiento Endotelial Vascular/metabolismo , Xenopus laevis
5.
Dev Biol ; 318(1): 172-83, 2008 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-18439993

RESUMEN

Netrin-1 is a bifunctional axonal guidance cue, capable of attracting or repelling developing axons via activation of receptors of the deleted in colorectal cancer (DCC) and uncoordinated 5 (UNC5) families, respectively. In addition to its role in axon guidance, Netrin-1 has been implicated in angiogenesis, where it may also act as a bifunctional cue. Attractive effects of Netrin-1 on endothelial cells appear to be mediated by an as yet unknown receptor, while repulsion of developing blood vessels in mouse embryos is mediated by the UNC5B receptor. To explore evolutionary conservation of vascular UNC5B expression and function, we have cloned the chick unc5b homologue. Chick and quail embryos showed unc5b expression in arterial EC and sprouting angiogenic capillaries. To test if Netrin-1 displayed pro- or anti-angiogenic activities in the avian embryo, we grafted cell lines expressing recombinant chick or human Netrin-1 at different stages of development. Netrin-1 expressing cells inhibited angiogenic sprouting of unc5b expressing blood vessels, but had no pro-angiogenic activity at any stage of development examined. Netrin-1 also had no effect on the recruitment of circulating endothelial precursor cells. Taken together, these data indicate that vascular unc5b expression and function is conserved between chick and mice.


Asunto(s)
Embrión de Pollo , Neovascularización Fisiológica , Factores de Crecimiento Nervioso/metabolismo , Codorniz/embriología , Proteínas Supresoras de Tumor/metabolismo , Animales , Vasos Sanguíneos/citología , Vasos Sanguíneos/embriología , Vasos Sanguíneos/metabolismo , Línea Celular , Movimiento Celular/fisiología , Regulación del Desarrollo de la Expresión Génica , Humanos , Ratones , Neoplasias/metabolismo , Neoplasias/patología , Factores de Crecimiento Nervioso/genética , Receptores de Netrina , Netrina-1 , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/metabolismo , Proteínas Supresoras de Tumor/genética , Factor A de Crecimiento Endotelial Vascular/genética , Factor A de Crecimiento Endotelial Vascular/metabolismo
6.
Novartis Found Symp ; 283: 77-80; discussion 80-6, 238-41, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-18300415

RESUMEN

Blood vessels and nerves are structurally similar, complex branched networks that require guidance to ensure their proper positioning in the body. Recent studies have demonstrated that specialized endothelial cells, resembling axonal growth cones, are located at the tips of growing capillaries. These endothelial tip cells guide outgrowing capillaries in response to gradients of extracellular matrix-bound vascular endothelial growth factor (VEGF). Here we show that endothelial tip cell formation and vessel branching are negatively regulated by the Notch ligand Delta-like 4 (Dll4). Heterozygous deletion of Dll4 or pharmacological inhibition of Notch signalling using gamma-secretase inhibitor revealed a striking vascular phenotype, with greatly increased numbers of filopodia-extending endothelial tip cells and increased expression of tip cell marker genes compared to controls. Filopodia extension in Dll4+/- retinal vessels required VEGF and was inhibited when VEGF signalling was blocked. While VEGF expression was not significantly altered in Dll4+- retinas, Dll4+/- vessels showed increased expression of VEGF Receptor 2 and decreased expression of VEGF Receptor 1 compared to wildtype, suggesting that they could be more responsive to VEGF stimulation. In addition, expression of Dll4 in wildtype tip cells was itself decreased when VEGF signalling was blocked, indicating that Dll4 may act downstream of VEGF as a 'brake' on VEGF-mediated angiogenic sprouting. Taken together, these data reveal Dll4 as a novel negative regulator of vascular sprouting and vessel branching that is required for normal vascular network formation during development.


Asunto(s)
Vasos Sanguíneos/embriología , Tipificación del Cuerpo , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Proteínas de la Membrana/metabolismo , Proteínas Adaptadoras Transductoras de Señales , Animales , Proteínas de Unión al Calcio , Ratones , Receptores Notch/metabolismo , Vasos Retinianos/embriología , Transducción de Señal
7.
Int J Dev Biol ; 49(2-3): 259-67, 2005.
Artículo en Inglés | MEDLINE | ID: mdl-15906240

RESUMEN

The adult vascular system is composed of an arterial, a venous and a lymphatic compartment. These different compartments respectively provide oxygen and nutrients to peripheral organs, remove carbon dioxide and waste products and maintain an immune barrier to defend the host against foreign organisms. Malfunctions of the vascular system represent a major cause of mortality and disease in developed countries. Understanding of the molecular mechanisms regulating vascular system development and maintenance is thus crucial for the design of therapies to cure vascular diseases. The molecules implicated in the control of physiological and pathological angiogenesis in the adult already function during embryonic development. Indeed, the survival of the embryo also critically depends on the establishment of a functional circulatory loop. Here we review our current knowledge about the emergence of endothelial precursor cells in the embryo, of their assembly into the primary vascular plexus and of the remodeling of this plexus into arteries and veins. We also focus on the molecular mechanisms controlling the development of arteries, veins and lymphatic vessels.


Asunto(s)
Arterias/embriología , Células Madre Hematopoyéticas/citología , Venas/embriología , Animales , Capilares/citología , Capilares/embriología , Capilares/fisiología , Diferenciación Celular , Desarrollo Embrionario , Células Madre Hematopoyéticas/fisiología , Humanos , Sistema Linfático/embriología , Morfogénesis
8.
Dev Cell ; 20(1): 33-46, 2011 Jan 18.
Artículo en Inglés | MEDLINE | ID: mdl-21238923

RESUMEN

Robo4 is an endothelial cell-specific member of the Roundabout axon guidance receptor family. To identify Robo4 binding partners, we performed a protein-protein interaction screen with the Robo4 extracellular domain. We find that Robo4 specifically binds to UNC5B, a vascular Netrin receptor, revealing unexpected interactions between two endothelial guidance receptors. We show that Robo4 maintains vessel integrity by activating UNC5B, which inhibits signaling downstream of vascular endothelial growth factor (VEGF). Function-blocking monoclonal antibodies against Robo4 and UNC5B increase angiogenesis and disrupt vessel integrity. Soluble Robo4 protein inhibits VEGF-induced vessel permeability and rescues barrier defects in Robo4(-/-) mice, but not in mice treated with anti-UNC5B. Thus, Robo4-UNC5B signaling maintains vascular integrity by counteracting VEGF signaling in endothelial cells, identifying a novel function of guidance receptor interactions in the vasculature.


Asunto(s)
Vasos Sanguíneos/metabolismo , Vasos Sanguíneos/patología , Neovascularización Patológica/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Receptores de Superficie Celular/metabolismo , Receptores Inmunológicos/metabolismo , Animales , Anticuerpos Bloqueadores/farmacología , Vasos Sanguíneos/efectos de los fármacos , Vasos Sanguíneos/enzimología , Permeabilidad Capilar/efectos de los fármacos , Activación Enzimática/efectos de los fármacos , Humanos , Ligandos , Ratones , Modelos Biológicos , Receptores de Netrina , Unión Proteica/efectos de los fármacos , Vasos Retinianos/efectos de los fármacos , Vasos Retinianos/metabolismo , Vasos Retinianos/patología , Transducción de Señal/efectos de los fármacos , Sus scrofa , Factor A de Crecimiento Endotelial Vascular/metabolismo , Familia-src Quinasas/metabolismo
9.
Nat Med ; 16(4): 420-8, 2010 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-20364125

RESUMEN

Hereditary hemorrhagic telangiectasia (HHT) is an inherited disorder characterized by vascular malformations. Many affected individuals develop recurrent nosebleeds, which can severely affect their quality of life and are clinically difficult to treat. We report here that treatment with thalidomide reduced the severity and frequency of nosebleeds (epistaxis) in the majority of a small group of subjects with HHT tested. The blood hemoglobin levels of the treated individuals rose as a result of reduced hemorrhage and enhanced blood vessel stabilization. In mice heterozygous for a null mutation in the Eng gene (encoding endoglin), an experimental model of HHT, thalidomide treatment stimulated mural cell coverage and thus rescued vessel wall defects. Thalidomide treatment increased platelet-derived growth factor-B (PDGF-B) expression in endothelial cells and stimulated mural cell activation. The effects of thalidomide treatment were partially reversed by pharmacological or genetic interference with PDGF signaling from endothelial cells to pericytes. Biopsies of nasal epithelium from individuals with HHT treated or not with thalidomide showed that similar mechanisms may explain the effects of thalidomide treatment in humans. Our findings demonstrate the ability of thalidomide to induce vessel maturation, which may be useful as a therapeutic strategy for the treatment of vascular malformations.


Asunto(s)
Vasos Sanguíneos/efectos de los fármacos , Epistaxis/tratamiento farmacológico , Telangiectasia Hemorrágica Hereditaria/tratamiento farmacológico , Talidomida/uso terapéutico , Anciano , Animales , Vasos Sanguíneos/crecimiento & desarrollo , Vasos Sanguíneos/fisiología , Modelos Animales de Enfermedad , Células Endoteliales/efectos de los fármacos , Células Endoteliales/fisiología , Hemoglobinas/análisis , Humanos , Ratones , Ratones Mutantes , Persona de Mediana Edad , Neovascularización Fisiológica/efectos de los fármacos , Proteínas Proto-Oncogénicas c-sis/biosíntesis , Talidomida/farmacología
10.
Proc Natl Acad Sci U S A ; 104(9): 3225-30, 2007 Feb 27.
Artículo en Inglés | MEDLINE | ID: mdl-17296941

RESUMEN

Delta-like 4 (Dll4) is a transmembrane ligand for Notch receptors that is expressed in arterial blood vessels and sprouting endothelial cells. Here we show that Dll4 regulates vessel branching during development by inhibiting endothelial tip cell formation. Heterozygous deletion of dll4 or pharmacological inhibition of Notch signaling using gamma-secretase inhibitor revealed a striking vascular phenotype, with greatly increased numbers of filopodia-extending endothelial tip cells and increased expression of tip cell marker genes compared with controls. Filopodia extension in dll4(+/-) retinal vessels required the vascular growth factor VEGF and was inhibited when VEGF signaling was blocked. Although VEGF expression was not significantly altered in dll4(+/-) retinas, dll4(+/-) vessels showed increased expression of VEGF receptor 2 and decreased expression of VEGF receptor 1 compared with wild-type, suggesting they could be more responsive to VEGF stimulation. In addition, expression of dll4 in wild-type tip cells was itself decreased when VEGF signaling was blocked, indicating that dll4 may act downstream of VEGF as a "brake" on VEGF-mediated angiogenic sprouting. Taken together, these data reveal Dll4 as a negative regulator of vascular sprouting and vessel branching that is required for normal vascular network formation during development.


Asunto(s)
Endotelio Vascular/embriología , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Proteínas de la Membrana/metabolismo , Vasos Retinianos/embriología , Transducción de Señal/fisiología , Factor A de Crecimiento Endotelial Vascular/metabolismo , Proteínas Adaptadoras Transductoras de Señales , Secretasas de la Proteína Precursora del Amiloide/antagonistas & inhibidores , Animales , Proteínas de Unión al Calcio , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/metabolismo , Inmunohistoquímica , Hibridación in Situ , Ratones , Ratones Mutantes , Receptores de Factores de Crecimiento Endotelial Vascular/metabolismo , Vasos Retinianos/efectos de los fármacos , Vasos Retinianos/metabolismo , Transducción de Señal/efectos de los fármacos , Triglicéridos/farmacología , Ácido gamma-Aminobutírico/análogos & derivados , Ácido gamma-Aminobutírico/farmacología
11.
Genes Dev ; 21(19): 2433-47, 2007 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-17908930

RESUMEN

Netrins are secreted molecules with roles in axonal growth and angiogenesis. The Netrin receptor UNC5B is required during embryonic development for vascular patterning, suggesting that it may also contribute to postnatal and pathological angiogenesis. Here we show that unc5b is down-regulated in quiescent adult vasculature, but re-expressed during sprouting angiogenesis in matrigel and tumor implants. Stimulation of UNC5B-expressing neovessels with an agonist (Netrin-1) inhibits sprouting angiogenesis. Genetic loss of function of unc5b reduces Netrin-1-mediated angiogenesis inhibition. Expression of UNC5B full-length receptor also triggers endothelial cell repulsion in response to Netrin-1 in vitro, whereas a truncated UNC5B lacking the intracellular signaling domain fails to induce repulsion. These data show that UNC5B activation inhibits sprouting angiogenesis, thus identifying UNC5B as a potential anti-angiogenic target.


Asunto(s)
Neovascularización Patológica/metabolismo , Factores de Crecimiento Nervioso/farmacología , Receptores de Superficie Celular/agonistas , Proteínas Supresoras de Tumor/farmacología , Animales , Colágeno/metabolismo , Combinación de Medicamentos , Endotelio Vascular/metabolismo , Laminina/metabolismo , Ratones , Ratones Mutantes , Factores de Crecimiento Nervioso/genética , Factores de Crecimiento Nervioso/metabolismo , Receptores de Netrina , Netrina-1 , Proteoglicanos/metabolismo , Seudópodos/efectos de los fármacos , Ratas , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/metabolismo , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismo
12.
Development ; 129(20): 4797-806, 2002 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-12361971

RESUMEN

Neuropilin 2 is a receptor for class III semaphorins and for certain members of the vascular endothelial growth factor family. Targeted inactivation of the neuropilin 2 gene (Nrp2) has previously shown its role in neural development. We report that neuropilin 2 expression in the vascular system is restricted to veins and lymphatic vessels. Homozygous Nrp2 mutants show absence or severe reduction of small lymphatic vessels and capillaries during development. This correlated with a reduction of DNA synthesis in the lymphatic endothelial cells of the mutants. Arteries, veins and larger, collecting lymphatic vessels developed normally, suggesting that neuropilin 2 is selectively required for the formation of small lymphatic vessels and capillaries.


Asunto(s)
Vasos Sanguíneos/anomalías , Sistema Linfático/anomalías , Neuropilina-2/genética , Animales , Vasos Sanguíneos/embriología , Vasos Sanguíneos/crecimiento & desarrollo , Células Epiteliales/fisiología , Femenino , Regulación del Desarrollo de la Expresión Génica , Sistema Linfático/embriología , Ratones , Ratones Mutantes , Neuropilina-2/metabolismo , Receptor 3 de Factores de Crecimiento Endotelial Vascular/metabolismo
13.
Development ; 131(2): 361-75, 2004 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-14681188

RESUMEN

Formation of the yolk sac vascular system and its connection to the embryonic circulation is crucial for embryo survival in both mammals and birds. Most mice with mutations in genes involved in vascular development die because of a failure to establish this circulatory loop. Surprisingly, formation of yolk sac arteries and veins has not been well described in the recent literature. Using time-lapse video-microscopy, we have studied arterial-venous differentiation in the yolk sac of chick embryos. Immediately after the onset of perfusion, the yolk sac exhibits a posterior arterial and an anterior venous pole, which are connected to each other by cis-cis endothelial interactions. To form the paired and interlaced arterial-venous pattern characteristic of mature yolk sac vessels, small caliber vessels of the arterial domain are selectively disconnected from the growing arterial tree and subsequently reconnected to the venous system, implying that endothelial plasticity is needed to fashion normal growth of veins. Arterial-venous differentiation and patterning are controlled by hemodynamic forces, as shown by flow manipulation and in situ hybridization with arterial markers ephrinB2 and neuropilin 1, which show that expression of both mRNAs is not genetically determined but plastic and regulated by flow. In vivo application of ephrinB2 or EphB4 in the developing yolk sac failed to produce any morphological effects. By contrast, ephrinB2 and EphB4 application in the allantois of older embryos resulted in the rapid formation of arterial-venous shunts. In conclusion, we show that flow shapes the global patterning of the arterial tree and regulates the activation of the arterial markers ephrinB2 and neuropilin 1.


Asunto(s)
Arterias/embriología , Venas/embriología , Saco Vitelino/irrigación sanguínea , Animales , Arterias/efectos de los fármacos , Arterias/fisiología , Embrión de Pollo , Coturnix , Efrina-B2/genética , Efrina-B2/farmacología , Regulación del Desarrollo de la Expresión Génica , Hemodinámica , Hibridación in Situ , Microscopía Electrónica de Rastreo , Neuropilina-1/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Receptor EphB4/fisiología , Proteínas Recombinantes/farmacología , Flujo Sanguíneo Regional , Venas/efectos de los fármacos , Venas/fisiología , Membrana Vitelina/irrigación sanguínea , Membrana Vitelina/efectos de los fármacos , Membrana Vitelina/embriología , Saco Vitelino/efectos de los fármacos , Saco Vitelino/embriología
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