El FGF2 como regulador de la actividad mitogénica de precursores neurales en el nicho celular del cerebro embrionario de ratón

A lo largo de la vida del individuo, las células precursoras neurales se encuentran alojadas en microentornos especializados conocidos como nichos germinales neurogénicos, que garantizan su mantenimiento y posibilitan la generación de nuevas neuronas, experimentando su momento de máxima actividad neurogénica durante el desarrollo. El fluido cerebroespinal embrionario (eCSF) ha sido identificado como uno de los elementos esenciales del nicho neurogénico del cerebro embrionario, contactando de manera directa con todas las células precursoras neuroepiteliales y demostrando, en virtud de mecanismos físicos y bioquímicos, una participación clave en la regulación de su comportamiento celular básico (supervivencia, replicación, diferenciación). En particular, el conocimiento de las bases moleculares de los mecanismos regulatorios de la proliferación de las NPCs en los nichos neurogénicos de los mamíferos, resulta indispensable para abordar el diseño de estrategias de neurorregeneración. El FGF2 es una de las moléculas que ha sido directamente relacionada con la expansión de la ‘reserva’ de NPCs en el cerebro embrionario y adulto, y ha sido identificada como uno de los componentes del eCSF en vertebrados. La presente tesis doctoral pretende estudiar la actividad del FGF2 presente en el eCSF, como regulador de la expansión/proliferación de las células precursoras neurales en el nicho germinal del cerebro embrionario de ratón.Departamento de Anatomía y RadiologíaDoctorado en Investigación Biomédic

Papel del FGF2 en la proliferación de las células neuroepiteliales en estadios tempranos del desarrollo embrionario del ratón

El sistema nervioso de los vertebrados se origina a partir de las células neuroepiteliales que constituyen la pared del tubo neural del embrión en desarrollo. Este tubo se origina mediante un proceso denominado neurulación, en el cual, una región del ectodermo de la superficie dorsal del embrión denominada placa neural, se invagina y, progresivamente, fusiona sus bordes y se aísla del resto del ectodermo, formando así una estructura cilíndrica inmersa en el mesénquima embrionario. A continuación, se da inicio a una “fase de expansión y vesiculación cerebral”, en la cual, el tubo neural se expande aceleradamente en su región anterior y se diferencia en cinco vesículas, precursoras del sistema nervioso central completo del adulto: telencéfalo, diencéfalo, mesencéfalo, metencéfalo y mielencéfalo (eje anteroposterior). Finalmente, se desarrolla la histiogénesis a lo largo de todo el neuroepitelioDepartamento de Anatomía y RadiologíaMáster en Investigación Biomédic

Embryonic cerebrospinal fluid influence in the subependymal neurogenic niche in adult mouse hippocampus

Producción CientíficaThe adult mouse hippocampal neurogenic niche is a complex structure which is not completely understood. It has mainly been related to the Subgranular layer of the dentate gyrus; however, as a result of differential neural stem cell populations reported in the subventricular zone of the lateral ventricle and associated with the hippocampus, the possibility remains of a multifocal niche reproducing developmental stages. Here, using a set of molecular markers for neural precursors, we describe in the adult mouse brain hippocampus the existence of a disperse population of neural precursors in the Subependymal Zone, the Dentate Migratory Stream and the hilus; these display dynamic behaviour compatible with neurogenesis. This supports the idea that the adult hippocampal niche cannot be restricted to the dentate gyrus subgranular layer. In other neurogenic niches such as the Subventricular Zone, a functional periventricular dependence has been shown due to the ability to respond to embryonic cerebro-spinal fluid. In this study, we demonstrate that neural precursors from the three areas studied (Sub-ependymal Zone, Dentate Migratory Stream and hilus) are able to modify their behaviour by increasing neurogenesis in a locally differential manner. Our results are compatible with the persistence in the adult mouse hippocampus of a neurogenic niche with the same spatial structure as that seen during development and early postnatal stages.Ministerio de Educación y Ciencia (BFU207/6516)Junta de Castilla y León (Consejería de Educación, GR195

Embryonic cerebrospinal fluid in brain development: neural progenitor control

Producción CientíficaDue to the effort of several research teams across the world, today we have a solid base of knowledge on the liquid contained in the brain cavities, its composition, and biological roles. Although the cerebrospinal fluid (CSF) is among the most relevant parts of the central nervous system from the physiological point of view, it seems that it is not a permanent and stable entity because its composition and biological properties evolve across life. So, we can talk about different CSFs during the vertebrate life span. In this review, we focus on the CSF in an interesting period, early in vertebrate development before the formation of the choroid plexus. This specific entity is called “embryonic CSF.” Based on the structure of the compartment, CSF composition, origin and circulation, and its interaction with neuroepithelial precursor cells (the target cells) we can conclude that embryonic CSF is different from the CSF in later developmental stages and from the adult CSF. This article presents arguments that support the singularity of the embryonic CSF, mainly focusing on its influence on neural precursor behavior during development and in adult life

Lens capsule HSPG-Perlecan regulates lens fibre differentiation during chick embryo development

Producción CientíficaLens fibre differentiation is a life-long process related with lens transparency, and is particularly intense during development, being related with an FGF-2 antero-posterior gradient at the equator level as the main growth factor involved which has been related with the basal membrane of the lens anlagen known as “Lens capsule”. However the lens fibre differentiation induced by FGF2 depends, as in other biological systems, on the local bioavailability of FGF-2 regulated by their relationship with extracellular matrix molecules as Heparan Sulphate Proteoglycans. Here, we try to clarify how Perlecan (a heparan sulphate proteoglycan specific from basement membranes) is involved in lens fibre differentiation at earliest stages of eye development. Our results show that Perlecan, is a major component in the lens capsule during the earliest stages of lens development in chick embryos being present during lens plate induction, lens vesicle stage and the onset of lens fibre differentiation. In order to demonstrate a direct involvement of HSPG-Perlecan in lens fibre differentiation, we generate depleted lenses by HSPG-Perlecan synthesis disruption and specific enzymatic digestion. The HSPG-Perlecan depleted lens show a significant delay or abolition in the lens fibre differentiation which remains in an immature cells displaying DNA synthesis in the posterior epithelium and a decrease in FGF2 lens expression. These data support the hypothesis that lens capsule HSPG-Perlecan is a key molecule involved in lens fibre differentiation during development, probably by involvement in FGF-2 biodisponibility.Ministerio de Educación y Ciencia (Grant BFU207/6516)Instituto de Salud Carlos III (Grant PIO20961)Junta de Castilla y León (Grants VA21A07, VA049/04, SAN673/VA15/08

Retinoic acid, under cerebrospinal fluid control, induces neurogenesis during early brain development

Producción CientíficaOne of the more intriguing subjects in neuroscience is how a precursor or stem cell is induced to differentiate into a neuron. Neurogenesis begins early in brain development and suddenly becomes a very intense process, which is related with the influence of Retinoic Acid. Here, using a biological test (F9-1.8 cells) in chick embryos, we show that ―in vivo‖ embryonic cerebrospinal fluid regulates mesencephalic-rombencephalic Isthmic Retinoic Acid synthesis and this effect has a direct influence on mesencephalic neuroepithelial precursors, inducing a significant increase in neurogenesis. This effect is mediated by the Retinol Binding Protein present in the embryonic cerebrospinal fluid. The knowledge of embryonic neurogenetic stimulus could be useful in the control of adult brain neurogenesis.Ministerio de Educación y Ciencia (BFU207/6516)Junta de Castilla y León (Consejería de Educación, GR195

Embryonic Cerebrospinal Fluid Activates Neurogenesis of Neural Precursors within the Subventricular Zone of the Adult Mouse Brain

Producción CientíficaIntroduction: There is a nondeveloped neurogenic potential in the adult mammalian brain, which could be the basis for neuroregenerative strategies. Many research efforts have been made to understand the control mechanisms which regulate the transition from a neural precursor to a neuron in the adult brain. Embryonic cerebrospinal fluid (CSF) is a complex fluid which has been shown to play a key role in neural precursor behavior during development, working as a powerful neurogenic inductor. We tested if the neurogenic properties of embryonic CSF are able to increase the neurogenic activity of neuronal precursors from the subventricular zone (SVZ) in the brains of adult mice. Results: Our results show that mouse embryonic CSF significantly increases the neurogenic activity in precursor cells from adult brain SVZ. This intense neurogenic effect was specific for embryonic CSF and was not induced by adult CSF. Conclusions: Embryonic CSF is a powerful neurogenesis inductor in homologous neuronal precursors in the adult brain. This property of embryonic CSF could be a useful tool in neuroregeneration strategies

Cultivo organotípico de neuroepitelio

Se explica el cultivo organotípico de neuroepitelio. Tambien, se realiza una demostración experimental.Departamento de Anatomía y Radiologí