RESUMEN
The cerebral vasculature is a dense network of arteries, capillaries, and veins. Quantifying variations of the vascular organization across individuals, brain regions, or disease models is challenging. We used immunolabeling and tissue clearing to image the vascular network of adult mouse brains and developed a pipeline to segment terabyte-sized multichannel images from light sheet microscopy, enabling the construction, analysis, and visualization of vascular graphs composed of over 100 million vessel segments. We generated datasets from over 20 mouse brains, with labeled arteries, veins, and capillaries according to their anatomical regions. We characterized the organization of the vascular network across brain regions, highlighting local adaptations and functional correlates. We propose a classification of cortical regions based on the vascular topology. Finally, we analysed brain-wide rearrangements of the vasculature in animal models of congenital deafness and ischemic stroke, revealing that vascular plasticity and remodeling adopt diverging rules in different models.
Asunto(s)
Adaptación Fisiológica , Encéfalo/irrigación sanguínea , Capilares/anatomía & histología , Arterias Cerebrales/anatomía & histología , Venas Cerebrales/anatomía & histología , Remodelación Vascular , Animales , Capilares/patología , Arterias Cerebrales/patología , Venas Cerebrales/patología , Femenino , Masculino , Ratones , Ratones Endogámicos C57BL , Privación Sensorial , Estrés Psicológico/etiología , Estrés Psicológico/patología , Accidente Cerebrovascular/patologíaRESUMEN
Current opinion holds that pigment cells, melanocytes, are derived from neural crest cells produced at the dorsal neural tube and that migrate under the epidermis to populate all parts of the skin. Here, we identify growing nerves projecting throughout the body as a stem/progenitor niche containing Schwann cell precursors (SCPs) from which large numbers of skin melanocytes originate. SCPs arise as a result of lack of neuronal specification by Hmx1 homeobox gene function in the neural crest ventral migratory pathway. Schwann cell and melanocyte development share signaling molecules with both the glial and melanocyte cell fates intimately linked to nerve contact and regulated in an opposing manner by Neuregulin and soluble signals including insulin-like growth factor and platelet-derived growth factor. These results reveal SCPs as a cellular origin of melanocytes, and have broad implications on the molecular mechanisms regulating skin pigmentation during development, in health and pigmentation disorders.
Asunto(s)
Melanocitos/citología , Células de Schwann/citología , Piel/inervación , Animales , Diferenciación Celular , Movimiento Celular , Proteínas de Homeodominio , Ratones , Neuroglía , Receptor ErbB-3/metabolismo , Células Madre/citología , Factores de Transcripción/metabolismoRESUMEN
Although cardiac neural crest cells are required at early stages of arterial valve development, their contribution during valvular leaflet maturation remains poorly understood. Here, we show in mouse that neural crest cells from pre-otic and post-otic regions make distinct contributions to the arterial valve leaflets. Genetic fate-mapping analysis of Krox20-expressing neural crest cells shows a large contribution to the borders and the interleaflet triangles of the arterial valves. Loss of Krox20 function results in hyperplastic aortic valve and partially penetrant bicuspid aortic valve formation. Similar defects are observed in neural crest Krox20-deficient embryos. Genetic lineage tracing in Krox20-/- mutant mice shows that endothelial-derived cells are normal, whereas neural crest-derived cells are abnormally increased in number and misplaced in the valve leaflets. In contrast, genetic ablation of Krox20-expressing cells is not sufficient to cause an aortic valve defect, suggesting that adjacent cells can compensate this depletion. Our findings demonstrate a crucial role for Krox20 in arterial valve development and reveal that an excess of neural crest cells may be associated with bicuspid aortic valve.
Asunto(s)
Válvula Aórtica/anomalías , Proteína 2 de la Respuesta de Crecimiento Precoz/metabolismo , Células Endoteliales/metabolismo , Enfermedades de las Válvulas Cardíacas/embriología , Miocardio/metabolismo , Cresta Neural/metabolismo , Animales , Válvula Aórtica/citología , Válvula Aórtica/embriología , Enfermedad de la Válvula Aórtica Bicúspide , Proteína 2 de la Respuesta de Crecimiento Precoz/genética , Células Endoteliales/citología , Ratones , Ratones Noqueados , Miocardio/citología , Cresta Neural/citologíaRESUMEN
A mismatch between optical power and ocular axial length results in refractive errors. Uncorrected refractive errors constitute the most common cause of vision loss and second leading cause of blindness worldwide. Although the retina is known to play a critical role in regulating ocular growth and refractive development, the precise factors and mechanisms involved are poorly defined. We have previously identified a role for the secreted serine protease PRSS56 in ocular size determination and PRSS56 variants have been implicated in the etiology of both hyperopia and myopia, highlighting its importance in refractive development. Here, we use a combination of genetic mouse models to demonstrate that Prss56 mutations leading to reduced ocular size and hyperopia act via a loss of function mechanism. Using a conditional gene targeting strategy, we show that PRSS56 derived from Müller glia contributes to ocular growth, implicating a new retinal cell type in ocular size determination. Importantly, we demonstrate that persistent activity of PRSS56 is required during distinct developmental stages spanning the pre- and post-eye opening periods to ensure optimal ocular growth. Thus, our mouse data provide evidence for the existence of a molecule contributing to both the prenatal and postnatal stages of human ocular growth. Finally, we demonstrate that genetic inactivation of Prss56 rescues axial elongation in a mouse model of myopia caused by a null mutation in Egr1. Overall, our findings identify PRSS56 as a potential therapeutic target for modulating ocular growth aimed at preventing or slowing down myopia, which is reaching epidemic proportions.
Asunto(s)
Ojo/crecimiento & desarrollo , Regulación del Desarrollo de la Expresión Génica , Errores de Refracción/genética , Serina Proteasas/metabolismo , Animales , Modelos Animales de Enfermedad , Proteína 1 de la Respuesta de Crecimiento Precoz/genética , Proteína 1 de la Respuesta de Crecimiento Precoz/metabolismo , Ojo/citología , Ojo/embriología , Femenino , Humanos , Hiperopía/genética , Masculino , Ratones Mutantes , Ratones Transgénicos , Miopía/genética , Miopía/patología , Neuroglía/metabolismo , Refracción Ocular/genética , Refracción Ocular/fisiología , Errores de Refracción/prevención & control , Serina Proteasas/genéticaRESUMEN
Central nervous system (CNS) lesions are a leading cause of death and disability worldwide. Three-dimensional neural cultures in biomaterials offer more physiologically relevant models for disease studies, toxicity screenings or in vivo transplantations. Herein, we describe the development and use of pullulan/dextran polysaccharide-based scaffolds for 3D neuronal culture. We first assessed scaffolding properties upon variation of the concentration (1%, 1.5%, 3% w/w) of the cross-linking agent, sodium trimetaphosphate (STMP). The lower STMP concentration (1%) allowed us to generate scaffolds with higher porosity (59.9 ± 4.6%), faster degradation rate (5.11 ± 0.14 mg/min) and lower elastic modulus (384 ± 26 Pa) compared with 3% STMP scaffolds (47 ± 2.1%, 1.39 ± 0.03 mg/min, 916 ± 44 Pa, respectively). Using primary cultures of embryonic neurons from PGKCre, Rosa26tdTomato embryos, we observed that in 3D culture, embryonic neurons remained in aggregates within the scaffolds and did not attach, spread or differentiate. To enhance neuronal adhesion and neurite outgrowth, we then functionalized the 1% STMP scaffolds with laminin. We found that treatment of the scaffold with a 100 µg/mL solution of laminin, combined with a subsequent freeze-drying step, created a laminin mesh network that significantly enhanced embryonic neuron adhesion, neurite outgrowth and survival. Such scaffold therefore constitutes a promising neuron-compatible and biodegradable biomaterial.
Asunto(s)
Materiales Biocompatibles/química , Técnicas de Cultivo Tridimensional de Células/métodos , Embrión de Mamíferos/citología , Neuronas/citología , Polisacáridos/química , Andamios del Tejido/química , Animales , Adhesión Celular , Supervivencia Celular , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos DBA , Porosidad , Ingeniería de TejidosRESUMEN
Schwann cells (SC) enter the central nervous system (CNS) in pathophysiological conditions. However, how SC invade the CNS to remyelinate central axons remains undetermined. We studied SC migratory behavior ex vivo and in vivo after exogenous transplantation in the demyelinated spinal cord. The data highlight for the first time that SC migrate preferentially along blood vessels in perivascular extracellular matrix (ECM), avoiding CNS myelin. We demonstrate in vitro and in vivo that this migration route occurs by virtue of a dual mode of action of Eph/ephrin signaling. Indeed, EphrinB3, enriched in myelin, interacts with SC Eph receptors, to drive SC away from CNS myelin, and triggers their preferential adhesion to ECM components, such as fibronectin via integrinß1 interactions. This complex interplay enhances SC migration along the blood vessel network and together with lesion-induced vascular remodeling facilitates their timely invasion of the lesion site. These novel findings elucidate the mechanism by which SC invade and contribute to spinal cord repair.
Asunto(s)
Vasos Sanguíneos , Movimiento Celular/fisiología , Efrina-B3/metabolismo , Remielinización/fisiología , Células de Schwann/fisiología , Médula Espinal/metabolismo , Animales , Enfermedades Desmielinizantes/patología , Femenino , Fibronectinas/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Transducción de Señal/fisiología , Médula Espinal/patologíaRESUMEN
Boundary cap cells (BC), which express the transcription factor Krox20, participate in the formation of the boundary between the central nervous system and the peripheral nervous system. To study BC stemness, we developed a method to purify and amplify BC in vitro from Krox20(Cre/+), R26R(YFP/+) mouse embryos. We show that BC progeny are EGF/FGF2-responsive, form spheres, and express neural crest markers. Upon growth factor withdrawal, BC progeny gave rise to multiple neural crest and CNS lineages. Transplanted into the developing murine forebrain, they successfully survived, migrated, and integrated within the host environment. Surprisingly, BC progeny generated exclusively CNS cells, including neurons, astrocytes, and myelin-forming oligodendrocytes. In vitro experiments indicated that a sequential combination of ventralizing morphogens and glial growth factors was necessary to reprogram BC into oligodendrocytes. Thus, BC progeny are endowed with differentiation plasticity beyond the peripheral nervous system. The demonstration that CNS developmental cues can reprogram neural crest-derived stem cells into CNS derivatives suggests that BC could serve as a source of cell type-specific lineages, including oligodendrocytes, for cell-based therapies to treat CNS disorders.
Asunto(s)
Diferenciación Celular , Sistema Nervioso Periférico/citología , Células Madre/citología , Animales , Linaje de la Célula , Movimiento Celular , Células Cultivadas , Citometría de Flujo , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos DBA , Oligodendroglía/metabolismoRESUMEN
Neural cells are segregated into their distinct central nervous system (CNS) and peripheral nervous system (PNS) domains. However, at specialized regions of the nervous system known as transition zones (TZs), glial cells from both the CNS and PNS are uniquely present with other specialized TZ cells. Herein we review the current understanding of vertebrate TZ cells. The article discusses the distinct cells at vertebrate TZs with a focus on cells that are located on the peripheral side of the spinal cord TZs. In addition to the developmental origin and differentiation of these TZ cells, the functional importance and the role of TZ cells in disease are highlighted. This article also reviews the common and unique features of vertebrate TZs from zebrafish to mice. We propose challenges and open questions in the field that could lead to exciting insights in the field of glial biology.
RESUMEN
Congenital pseudarthrosis of the tibia (CPT) is a severe pathology marked by spontaneous bone fractures that fail to heal, leading to fibrous nonunion. Half of patients with CPT are affected by the multisystemic genetic disorder neurofibromatosis type 1 (NF1) caused by mutations in the NF1 tumor suppressor gene, a negative regulator of RAS-mitogen-activated protein kinase (MAPK) signaling pathway. Here, we analyzed patients with CPT and Prss56-Nf1 knockout mice to elucidate the pathogenic mechanisms of CPT-related fibrous nonunion and explored a pharmacological approach to treat CPT. We identified NF1-deficient Schwann cells and skeletal stem/progenitor cells (SSPCs) in pathological periosteum as affected cell types driving fibrosis. Whereas NF1-deficient SSPCs adopted a fibrotic fate, NF1-deficient Schwann cells produced critical paracrine factors including transforming growth factor-ß and induced fibrotic differentiation of wild-type SSPCs. To counteract the elevated RAS-MAPK signaling in both NF1-deficient Schwann cells and SSPCs, we used MAPK kinase (MEK) and Src homology 2 containing protein tyrosine phosphatase 2 (SHP2) inhibitors. Combined MEK-SHP2 inhibition in vivo prevented fibrous nonunion in the Prss56-Nf1 knockout mouse model, providing a promising therapeutic strategy for the treatment of fibrous nonunion in CPT.
Asunto(s)
Ratones Noqueados , Neurofibromina 1 , Proteína Tirosina Fosfatasa no Receptora Tipo 11 , Seudoartrosis , Células de Schwann , Animales , Femenino , Humanos , Masculino , Ratones , Diferenciación Celular/efectos de los fármacos , Fibrosis , Quinasas de Proteína Quinasa Activadas por Mitógenos/metabolismo , Quinasas de Proteína Quinasa Activadas por Mitógenos/antagonistas & inhibidores , Neurofibromatosis 1/patología , Neurofibromatosis 1/metabolismo , Neurofibromatosis 1/complicaciones , Neurofibromina 1/metabolismo , Neurofibromina 1/genética , Proteína Tirosina Fosfatasa no Receptora Tipo 11/metabolismo , Proteína Tirosina Fosfatasa no Receptora Tipo 11/antagonistas & inhibidores , Seudoartrosis/patología , Seudoartrosis/metabolismo , Seudoartrosis/congénito , Células de Schwann/metabolismo , Células de Schwann/efectos de los fármacos , Células de Schwann/patología , Células Madre/metabolismo , Células Madre/efectos de los fármacos , Tibia/patologíaRESUMEN
The transcription factor EGR2 is expressed in Schwann cells, where it controls peripheral nerve myelination. Mutations of EGR2 have been found in patients with congenital hypomyelinating neuropathy or Charcot-Marie-Tooth disease type 1D. In a patient with congenital amyelinating neuropathy, we observed pathological abnormalities recapitulating the peripheral nervous system phenotype of homozygous Egr2-null mice. This patient, born from consanguineous parents, showed no EGR2 immunoreactivity in Schwann cells and harbored a homozygous 10.7-kilobase-long deletion encompassing a myelin-specific enhancer of EGR2. This regulatory mutation is the first genetic abnormality associated with congenital amyelinating neuropathy in humans.
Asunto(s)
Enfermedad de Charcot-Marie-Tooth/genética , Enfermedad de Charcot-Marie-Tooth/patología , Proteína 2 de la Respuesta de Crecimiento Precoz/genética , Elementos de Facilitación Genéticos/genética , Vaina de Mielina/patología , Secuencia de Bases , Femenino , Homocigoto , Humanos , Lactante , Recién Nacido , Datos de Secuencia Molecular , Linaje , Reacción en Cadena de la Polimerasa , Eliminación de SecuenciaRESUMEN
In addition to their roles in protecting nerves and increasing conduction velocity, peripheral glia plays key functions in blood vessel development by secreting molecules governing arteries alignment and maturation with nerves. Here, we show in mice that a specific, nerve-attached cell population, derived from boundary caps (BCs), constitutes a major source of mural cells for the developing skin vasculature. Using Cre-based reporter cell tracing and single-cell transcriptomics, we show that BC derivatives migrate into the skin along the nerves, detach from them, and differentiate into pericytes and vascular smooth muscle cells. Genetic ablation of this population affects the organization of the skin vascular network. Our results reveal the heterogeneity and extended potential of the BC population in mice, which gives rise to mural cells, in addition to previously described neurons, Schwann cells, and melanocytes. Finally, our results suggest that mural specification of BC derivatives takes place before their migration along nerves to the mouse skin.
Asunto(s)
Cresta Neural , Tubo Neural , Ratones , Animales , Cresta Neural/fisiología , Neuroglía , Células de Schwann , Piel , Diferenciación Celular/fisiologíaRESUMEN
Cutaneous neurofibromas (cNFs) are a hallmark of patients with the neurofibromatosis type 1 (NF1) genetic disorder. These benign nerve sheath tumors, which can amount to thousands, develop from puberty onward, often cause pain and are considered by patients to be the primary burden of the disease. Mutations of NF1, encoding a negative regulator of the RAS signaling pathway, in the Schwann cell (SCs) lineage are considered to be at the origin of cNFs. The mechanisms governing cNFs development are poorly understood, and therapeutics to reduce cNFs are missing, mainly due to the lack of appropriate animal models. To address this, we designed the Nf1-KO mouse model that develops cNFs. Using this model, we found that cNFs development is a singular event and goes through 3 successive stages: initiation, progression, and stabilization characterized by changes in the proliferative and MAPK activities of tumor SCs. We found that skin trauma accelerated the development of cNFs and further used this model to explore the efficacy of the MEK inhibitor binimetinib to cure these tumors. We showed that while topically delivered binimetinib has a selective and minor effect on mature cNFs, the same drug prevents their development over long periods.
Asunto(s)
Neurofibroma , Neurofibromatosis 1 , Neoplasias Cutáneas , Humanos , Ratones , Animales , Neurofibromatosis 1/tratamiento farmacológico , Neurofibromatosis 1/genética , Neurofibromatosis 1/metabolismo , Neurofibroma/tratamiento farmacológico , Neurofibroma/genética , Bencimidazoles , Neoplasias Cutáneas/tratamiento farmacológico , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/prevención & control , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Quinasas Activadas por MitógenosRESUMEN
Neurofibromatosis type 1 (NF1) is caused by a nonfunctional copy of the NF1 tumor suppressor gene that predisposes patients to the development of cutaneous neurofibromas (cNFs), the skin tumor that is the hallmark of this condition. Innumerable benign cNFs, each appearing by an independent somatic inactivation of the remaining functional NF1 allele, form in nearly all patients with NF1. One of the limitations in developing a treatment for cNFs is an incomplete understanding of the underlying pathophysiology and limitations in experimental modeling. Recent advances in preclinical in vitro and in vivo modeling have substantially enhanced our understanding of cNF biology and created unprecedented opportunities for therapeutic discovery. We discuss the current state of cNF preclinical in vitro and in vivo model systems, including two- and three-dimensional cell cultures, organoids, genetically engineered mice, patient-derived xenografts, and porcine models. We highlight the models' relationship to human cNFs and how they can be used to gain insight into cNF development and therapeutic discovery.
Asunto(s)
Neurofibroma , Neurofibromatosis 1 , Neoplasias Cutáneas , Ratones , Humanos , Animales , Porcinos , Neurofibromatosis 1/genética , Neurofibromatosis 1/terapia , Mutación , Neurofibroma/genética , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/patología , AlelosRESUMEN
Peripheral nerves are vascularized by a dense network of blood vessels to guarantee their complex function. Despite the crucial role of vascularization to ensure nerve homeostasis and regeneration, the mechanisms governing nerve invasion by blood vessels remain poorly understood. We found, in mice, that the sciatic nerve invasion by blood vessels begins around embryonic day 16 and continues until birth. Interestingly, intra-nervous blood vessel density significantly decreases during post-natal period, starting from P10. We show that, while the axon guidance molecule Netrin-1 promotes nerve invasion by blood vessels via the endothelial receptor UNC5B during embryogenesis, myelinated Schwann cells negatively control intra-nervous vascularization during post-natal period.
Asunto(s)
Neovascularización Fisiológica , Fibras Nerviosas Mielínicas/fisiología , Netrina-1/genética , Células de Schwann/fisiología , Nervio Ciático/fisiología , Animales , Movimiento Celular , Femenino , Masculino , Ratones , Neovascularización Patológica , Regeneración Nerviosa , Netrina-1/metabolismo , Nervio Ciático/crecimiento & desarrolloRESUMEN
CNS/PNS interfaces constitute cell boundaries, because they delimit territories with different neuronal and glial contents. Despite their potential interest in regenerative medicine, the mechanisms restricting oligodendrocytes and astrocytes to the CNS and Schwann cells to the PNS in mammals are not known. To investigate the involvement of peripheral glia and myelin in the maintenance of the CNS/PNS boundary, we have first made use of different mouse mutants. We show that depletion of Schwann cells and boundary cap cells or inactivation of Krox20/Egr2, a master regulatory gene for myelination in Schwann cells, results in transgression of the CNS/PNS boundary by astrocytes and oligodendrocytes and in myelination of nerve root axons by oligodendrocytes. In contrast, such migration does not occur with the Trembler(J) mutation, which prevents PNS myelination without affecting Krox20 expression. Altogether, these data suggest that maintenance of the CNS/PNS boundary requires a Krox20 function separable from myelination control. Finally, we have analyzed a human patient affected by a congenital amyelinating neuropathy, associated with the absence of the KROX20 protein in Schwann cells. In this case, the nerve roots were also invaded by oligodendrocytes and astrocytes. This indicates that transgression of the CNS/PNS boundary by central glia can occur in pathological situations in humans and suggests that the underlying mechanisms are common with the mouse.
Asunto(s)
Sistema Nervioso Central/fisiología , Proteína 2 de la Respuesta de Crecimiento Precoz/metabolismo , Neuroglía/fisiología , Sistema Nervioso Periférico/fisiología , Animales , Astrocitos/fisiología , Astrocitos/ultraestructura , Axones/fisiología , Axones/ultraestructura , Movimiento Celular/fisiología , Sistema Nervioso Central/ultraestructura , Proteína 2 de la Respuesta de Crecimiento Precoz/genética , Humanos , Lactante , Ratones , Ratones Transgénicos , Vaina de Mielina/fisiología , Vaina de Mielina/ultraestructura , Neuroglía/ultraestructura , Oligodendroglía/fisiología , Oligodendroglía/ultraestructura , Sistema Nervioso Periférico/ultraestructura , Enfermedades del Sistema Nervioso Periférico/metabolismo , Enfermedades del Sistema Nervioso Periférico/patología , Células de Schwann/fisiología , Células de Schwann/ultraestructura , Raíces Nerviosas Espinales/fisiología , Raíces Nerviosas Espinales/ultraestructuraRESUMEN
CNS/PNS interfaces constitute cell boundaries, defining territories with different neuronal and glial contents. Despite their potential implications for regenerative medicine, the mechanisms that restrict oligodendrocytes and astrocytes to the CNS and Schwann cells to the PNS are not known in mammals. To investigate the involvement of peripheral glia and myelin in CNS/PNS boundary maintenance, we first studied mutant mice. We found that inactivation of Krox20/Egr2, a master regulatory gene for myelination in Schwann cells, resulted in CNS/PNS boundary transgression by astrocytes and oligodendrocytes, and in myelination of nerve root axons by oligodendrocytes. In contrast, no such migration was observed in mice with the Trembler(J) mutation, which prevents PNS myelination without affecting Krox20 expression. These findings suggest that CNS/PNS boundary maintenance requires a new Krox20 function independent of myelination control. We also examined a patient with congenital amyelinating neuropathy, whose Schwann cells lack KROX20 protein. Interestingly, the patient's nerve roots were also invaded by oligodendrocytes and astrocytes, indicating that CNS/PNS boundary transgression by central glia can occur in human pathological situations and that the underlying mechanisms are the same as in mutant mice.
Asunto(s)
Sistema Nervioso Central/fisiología , Proteína 2 de la Respuesta de Crecimiento Precoz/fisiología , Sistema Nervioso Periférico/fisiología , HumanosRESUMEN
Neural crest (NC) cells are a multipotent, highly migratory cell population that generates most of the components of the peripheral nervous system (PNS), including the glial Schwann cells (SC) and boundary cap (BC) cells. These latter cells are located at the interface between the central nervous system and PNS, at the exit/entry points of ventral motor/dorsal sensory axons and give rise to all SC in the nerve roots and to a subset of nociceptive neurons and satellite cells in the dorsal root ganglia. In the present study we have compared BC cells with two closely related cell types, NC and Schwann cell precursors (SCpr), by RNA profiling. This led to the definition of a set of 10 genes that show specific expression in BC cells and/or in their derivatives along the nerve roots. Analysis of the expression of these genes during mouse development revealed novel features, of those most important are: (i) dorsal and ventral nerve root BC cell derivatives express different sets of genes, suggesting that they have distinct properties; (ii) these cells undergo major modifications in their gene expression pattern between embryonic days 14.5 and 17.5, possibly linked to the SCpr-immature Schwann cell transition; (iii) nerve roots SC differ from more distal SC not only in their origins and locations, but also in their gene expression patterns. In conclusion, the identification of these novel makers opens the way for a detailed characterization of BC cells in both mouse and man.
Asunto(s)
Regulación del Desarrollo de la Expresión Génica , Cresta Neural/embriología , Cresta Neural/fisiología , Animales , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Biomarcadores/metabolismo , Proteína 2 de la Respuesta de Crecimiento Precoz/genética , Proteína 2 de la Respuesta de Crecimiento Precoz/metabolismo , Inmunohistoquímica , Hibridación in Situ , Ratones , Ratones Transgénicos , Análisis de Secuencia por Matrices de Oligonucleótidos , ARN/metabolismo , Receptores del Factor Natriurético Atrial/genética , Receptores del Factor Natriurético Atrial/metabolismo , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Proteínas Ribosómicas/genética , Proteínas Ribosómicas/metabolismo , Células de Schwann/fisiología , Raíces Nerviosas Espinales/embriología , Raíces Nerviosas Espinales/fisiología , Células Madre/fisiologíaRESUMEN
Patients carrying an inactive NF1 allele develop tumors of Schwann cell origin called neurofibromas (NF). Genetically engineered mouse models have significantly enriched our understanding of plexiform forms of NFs (pNF). However, this has not been the case for cutaneous neurofibromas (cNF), observed in all NF1 patients, as no previous model recapitulates their development. Here, we show that conditional Nf1 inactivation in Prss56-positive boundary cap cells leads to bona fide pNFs and cNFs. This work identifies subepidermal glia as a likely candidate for the cellular origin of cNFs and provides insights on disease mechanisms, revealing a long, multistep pathologic process in which inflammation-related signals play a pivotal role. This new mouse model is an important asset for future clinical and therapeutic investigations of NF1-associated neurofibromas. SIGNIFICANCE: Patients affected by NF1 develop numerous cNFs. We present a mouse model that faithfully recapitulates cNFs, identify a candidate cell type at their origin, analyze the steps involved in their formation, and show that their development is dramatically accelerated by skin injury. These findings have important clinical/therapeutic implications.This article is highlighted in the In This Issue feature, p. 1.
Asunto(s)
Neurofibroma/metabolismo , Neurofibromatosis 1/metabolismo , Neurofibromina 1/genética , Células de Schwann/metabolismo , Neoplasias Cutáneas/metabolismo , Animales , Modelos Animales de Enfermedad , Femenino , Masculino , Ratones , Ratones Noqueados , Mutación , Neurofibroma/etiología , Neurofibroma/genética , Neurofibroma/fisiopatología , Neurofibromatosis 1/complicaciones , Neurofibromatosis 1/genética , Neurofibromatosis 1/fisiopatología , Células de Schwann/fisiología , Neoplasias Cutáneas/etiología , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/fisiopatologíaRESUMEN
Spinal motor neurons must extend their axons into the periphery through motor exit points (MEPs), but their cell bodies remain within spinal motor columns. It is not known how this partitioning is established in development. We show here that motor neuron somata are confined to the CNS by interactions with a neural crest subpopulation, boundary cap (BC) cells that prefigure the sites of spinal MEPs. Elimination of BC cells by surgical or targeted genetic ablation does not perturb motor axon outgrowth but results in motor neuron somata migrating out of the spinal cord by translocating along their axons. Heterologous neural crest grafts in crest-ablated embryos stop motor neuron emigration. Thus, before the formation of a mature transitional zone at the MEP, BC cells maintain a cell-tight boundary that allows motor axons to cross but blocks neuron migration.
Asunto(s)
Neuronas Motoras/fisiología , Cresta Neural/citología , Cresta Neural/embriología , Médula Espinal/citología , Médula Espinal/embriología , Factores de Transcripción , Animales , Axones/fisiología , Movimiento Celular/fisiología , Embrión de Pollo , Proteínas de Unión al ADN/genética , Desnervación , Ratones , Ratones Mutantes , Microcirugia , Neuronas Motoras/ultraestructura , Cresta Neural/trasplante , Factor de Transcripción PAX3 , Factores de Transcripción Paired Box , Codorniz , Raíces Nerviosas Espinales/citología , Raíces Nerviosas Espinales/embriologíaRESUMEN
Boundary cap (BC) cells are neural crest derivatives that form clusters at the surface of the neural tube, at entry and exit points of peripheral nerve roots. Using various knock-in alleles of the mouse gene Egr2 (also known as Krox20), the expression of which, in trunk regions, is initially restricted to BC cells, we were able to trace BC cell progeny during development and analyze their fate. Trunk BC-derived cells migrated along peripheral axons and colonized spinal nerve roots and dorsal root ganglia (DRG). All Schwann cell precursors occupying the dorsal roots were derived from BC cells. In the DRG, BC-derived cells were the progenitors of both neurons, mainly nociceptive afferents, and satellite cells. These data indicate that BC cells constitute a source of peripheral nervous system (PNS) components that, after the major neural crest ventrolateral migratory stream, feeds a secondary wave of migration to the PNS.