RESUMO
Neural stem cells (NSCs) in the subventricular zone (SVZ) located along the lateral ventricles (LVs) of the mammalian brain continue to self-renew to produce new neurons after birth and into adulthood. Quiescent LV cells, which are situated close to the ependymal cells lining the LVs, are activated by choline acetyltransferase-positive (ChAT+) neurons within the subependymal (subep) region of the SVZ when these neurons are stimulated by projections from the anterior cingulate cortex (ACC). Here, we uncovered a signaling pathway activated by the ACC-subep-ChAT+ circuit responsible for the activation and proliferation of quiescent LV NSCs specifically in the ventral area of the SVZ. This circuit activated muscarinic M3 receptors on quiescent LV NSCs, which subsequently induced signaling mediated by the inositol 1,4,5-trisphosphate receptor type 1 (IP3R1). Downstream of IP3R1 activation, which would be expected to increase intracellular Ca2+, Ca2+-/calmodulin-dependent protein kinase II δ and the MAPK10 signaling pathway were stimulated and required for the proliferation of quiescent LV NSCs in the SVZ. These findings reveal the mechanisms that regulate quiescent LV NSCs and underscore the critical role of projections from the ACC in promoting their proliferative activity within the ventral SVZ.
Assuntos
Receptores de Inositol 1,4,5-Trifosfato , Ventrículos Laterais , Células-Tronco Neurais , Transdução de Sinais , Animais , Células-Tronco Neurais/metabolismo , Células-Tronco Neurais/citologia , Ventrículos Laterais/metabolismo , Ventrículos Laterais/citologia , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Camundongos , Colina O-Acetiltransferase/metabolismo , Colina O-Acetiltransferase/genética , Proliferação de Células , Receptor Muscarínico M3/metabolismo , Receptor Muscarínico M3/genética , Giro do Cíngulo/metabolismo , Giro do Cíngulo/citologia , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismoRESUMO
Neural stem cells (NSCs) persist in the adult mammalian brain and are able to give rise to new neurons and glia throughout life. The largest stem cell niche in the adult mouse brain is the ventricular-subventricular zone (V-SVZ) lining the lateral ventricles. Adult NSCs in the V-SVZ coexist in quiescent and actively proliferating states, and they exhibit a regionalized molecular identity. The importance of such spatial diversity is just emerging, as depending on their position within the niche, adult NSCs give rise to distinct subtypes of olfactory bulb interneurons and different types of glia. However, the functional relevance of stem cell heterogeneity in the V-SVZ is still poorly understood. Here, we put into perspective findings highlighting the importance of adult NSC diversity for brain plasticity, and how the body signals to brain stem cells in different physiological states to regulate their behavior.
Assuntos
Células-Tronco Adultas , Células-Tronco Neurais , Nicho de Células-Tronco , Animais , Células-Tronco Neurais/metabolismo , Células-Tronco Neurais/citologia , Células-Tronco Adultas/citologia , Células-Tronco Adultas/metabolismo , Humanos , Ventrículos Laterais/citologia , Neurogênese , Bulbo Olfatório/citologia , Bulbo Olfatório/metabolismo , Camundongos , Encéfalo/citologia , Diferenciação CelularRESUMO
The brain's neuroreparative capacity after injuries such as ischemic stroke is partly contained in the brain's neurogenic niches, primarily the subventricular zone (SVZ), which lies in close contact with the cerebrospinal fluid (CSF) produced by the choroid plexus (ChP). Despite the wide range of their proposed functions, the ChP/CSF remain among the most understudied compartments of the central nervous system (CNS). Here, we report a mouse genetic tool (the ROSA26iDTR mouse line) for noninvasive, specific, and temporally controllable ablation of CSF-producing ChP epithelial cells to assess the roles of the ChP and CSF in brain homeostasis and injury. Using this model, we demonstrate that ChP ablation causes rapid and permanent CSF volume loss in both aged and young adult brains, accompanied by disruption of ependymal cilia bundles. Surprisingly, ChP ablation did not result in overt neurological deficits at 1 mo postablation. However, we observed a pronounced decrease in the pool of SVZ neuroblasts (NBs) following ChP ablation, which occurs due to their enhanced migration into the olfactory bulb. In the middle cerebral artery occlusion model of ischemic stroke, NB migration into the lesion site was also reduced in the CSF-depleted mice. Thus, our study establishes an important role of ChP/CSF in regulating the regenerative capacity of the adult brain under normal conditions and after ischemic stroke.
Assuntos
Plexo Corióideo , Ventrículos Laterais , Neurogênese , Animais , Plexo Corióideo/metabolismo , Neurogênese/fisiologia , Camundongos , Ventrículos Laterais/metabolismo , Ventrículos Laterais/citologia , Células-Tronco Neurais/metabolismo , Células-Tronco Neurais/citologia , Acidente Vascular Cerebral/patologia , Acidente Vascular Cerebral/metabolismo , Acidente Vascular Cerebral/fisiopatologia , Masculino , Movimento Celular , Ventrículos Cerebrais/metabolismoRESUMO
Isolation and expansion of neural stem cells (NSCs) from the subventricular zone (SVZ) of the adult mouse brain can be achieved in a medium supplemented with basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) as mitogens, producing clonal aggregates known as neurospheres. This in vitro system is a valuable tool for studying NSC potential. Transfection of siRNAs or genes carried in plasmids can be used to induce perturbations to gene expression and study NSC biology. However, the exogenous nucleic acid delivery to NSC cultures is challenging due to the low efficiency of central nervous system (CNS) cells transfection. Here, we present an improved nucleofection system that achieves high efficiency of gene delivery in expanded NSCs from adult murine SVZ. We demonstrate that this relatively simple method enhances gene perturbation in adult NSCs, surpassing traditional transfection protocols with survival rates exceeding 80%. Moreover, this method can also be applied in primary isolated NSCs, providing a crucial advancement in gene function studies through gene expression manipulation via knockdown or overexpression in neurosphere cultures.
Assuntos
Células-Tronco Neurais , Transfecção , Animais , Células-Tronco Neurais/citologia , Células-Tronco Neurais/metabolismo , Camundongos , Transfecção/métodos , Ventrículos Laterais/citologia , Técnicas Citológicas/métodosRESUMO
The intricate process of neuronal differentiation integrates multiple signals to induce transcriptional, morphological, and electrophysiological changes that reshape the properties of neural precursor cells during their maturation and migration process. An increasing number of neurotransmitters and biomolecules have been identified as molecular signals that trigger and guide this process. In this sense, taurine, a sulfur-containing, non-essential amino acid widely expressed in the mammal brain, modulates the neuronal differentiation process. In this study, we describe the effect of taurine acting via the ionotropic GABAA receptor and the metabotropic GABAB receptor on the neuronal differentiation and electrophysiological properties of precursor cells derived from the subventricular zone of the mouse brain. Taurine stimulates the number of neurites and favors the dendritic complexity of the neural precursor cells, accompanied by changes in the somatic input resistance and the strength of inward and outward membranal currents. At the pharmacological level, the blockade of GABAA receptors inhibits these effects, whereas the stimulation of GABAB receptors has no positive effects on the taurine-mediated differentiation process. Strikingly, the blockade of the GABAB receptor with CGP533737 stimulates neurite outgrowth, dendritic complexity, and membranal current kinetics of neural precursor cells. The effects of taurine on the differentiation process involve Ca2+ mobilization and the activation of intracellular signaling cascades since chelation of intracellular calcium with BAPTA-AM, and inhibition of the CaMKII, ERK1/2, and Src kinase inhibits the neurite outgrowth of neural precursor cells of the subventricular zone.
Assuntos
Diferenciação Celular , Ventrículos Laterais , Células-Tronco Neurais , Receptores de GABA-A , Receptores de GABA-B , Animais , Células-Tronco Neurais/metabolismo , Células-Tronco Neurais/citologia , Células-Tronco Neurais/efeitos dos fármacos , Receptores de GABA-B/metabolismo , Camundongos , Diferenciação Celular/efeitos dos fármacos , Receptores de GABA-A/metabolismo , Ventrículos Laterais/citologia , Ventrículos Laterais/metabolismo , Taurina/farmacologia , Neurogênese/efeitos dos fármacos , Cálcio/metabolismoRESUMO
Neural precursor cells (NPCs) that persist in the postnatal/adult subventricular zone (SVZ) express connexins that form hemichannels and gap junctions. Gap junctional communication plays a role in NPC proliferation and differentiation during development, but its relevance on postnatal age remains to be elucidated. In this work we aimed to evaluate the effect of the blockade of gap junctional communication on proliferation and cell fate of NPCs obtained from the SVZ of postnatal rats. NPCs were isolated and expanded in culture as neurospheres. Electron microscopy revealed the existence of gap junctions among neurosphere cells. Treatment of cultures with octanol, a broad-spectrum gap junction blocker, or with Gap27, a specific blocker for gap junctions formed by connexin43, produced a significant decrease in bromodeoxyuridine incorporation. Octanol treatment also exerted a dose-dependent antiproliferative effect on glioblastoma cells. To analyze possible actions on NPC fate, cells were seeded in the absence of mitogens. Treatment with octanol led to an increase in the percentage of astrocytes and oligodendrocyte precursors, whereas the percentage of neurons remained unchanged. Gap27 treatment, in contrast, did not modify the differentiation pattern of SVZ NPCs. Our results indicate that general blockade of gap junctions with octanol induces significant effects on the behavior of postnatal SVZ NPCs, by reducing proliferation and promoting glial differentiation.
Assuntos
Diferenciação Celular , Proliferação de Células , Junções Comunicantes , Células-Tronco Neurais , Neuroglia , Octanóis , Animais , Junções Comunicantes/efeitos dos fármacos , Junções Comunicantes/metabolismo , Células-Tronco Neurais/efeitos dos fármacos , Células-Tronco Neurais/metabolismo , Células-Tronco Neurais/citologia , Proliferação de Células/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Ratos , Octanóis/farmacologia , Neuroglia/efeitos dos fármacos , Neuroglia/metabolismo , Neuroglia/citologia , Células Cultivadas , Ventrículos Laterais/citologia , Ventrículos Laterais/metabolismo , Ventrículos Laterais/efeitos dos fármacos , Conexina 43/metabolismo , Ratos Wistar , Astrócitos/efeitos dos fármacos , Astrócitos/metabolismo , Astrócitos/citologia , Animais Recém-Nascidos , HumanosRESUMO
Neural stem cells (NSCs) reside in discrete regions of the adult mammalian brain where they can differentiate into neurons, astrocytes, and oligodendrocytes. Several studies suggest that mitochondria have a major role in regulating NSC fate. Here, we evaluated mitochondrial properties throughout NSC differentiation and in lineage-specific cells. For this, we used the neurosphere assay model to isolate, expand, and differentiate mouse subventricular zone postnatal NSCs. We found that the levels of proteins involved in mitochondrial fusion (Mitofusin [Mfn] 1 and Mfn 2) increased, whereas proteins involved in fission (dynamin-related protein 1 [DRP1]) decreased along differentiation. Importantly, changes in mitochondrial dynamics correlated with distinct patterns of mitochondrial morphology in each lineage. Particularly, we found that the number of branched and unbranched mitochondria increased during astroglial and neuronal differentiation, whereas the area occupied by mitochondrial structures significantly reduced with oligodendrocyte maturation. In addition, comparing the three lineages, neurons revealed to be the most energetically flexible, whereas astrocytes presented the highest ATP content. Our work identified putative mitochondrial targets to enhance lineage-directed differentiation of mouse subventricular zone-derived NSCs.
Assuntos
Astrócitos , Diferenciação Celular , Linhagem da Célula , Dinaminas , Mitocôndrias , Dinâmica Mitocondrial , Células-Tronco Neurais , Neurônios , Oligodendroglia , Animais , Células-Tronco Neurais/metabolismo , Células-Tronco Neurais/citologia , Mitocôndrias/metabolismo , Camundongos , Diferenciação Celular/genética , Linhagem da Célula/genética , Astrócitos/metabolismo , Astrócitos/citologia , Oligodendroglia/metabolismo , Oligodendroglia/citologia , Neurônios/metabolismo , Neurônios/citologia , Células Cultivadas , Proteínas Mitocondriais/metabolismo , Proteínas Mitocondriais/genética , GTP Fosfo-Hidrolases/metabolismo , GTP Fosfo-Hidrolases/genética , Neurogênese , Ventrículos Laterais/citologia , Ventrículos Laterais/metabolismoRESUMO
Outer radial glia (oRG) emerge as cortical progenitor cells that support the development of an enlarged outer subventricular zone (oSVZ) and the expansion of the neocortex. The in vitro generation of oRG is essential to investigate the underlying mechanisms of human neocortical development and expansion. By activating the STAT3 signaling pathway using leukemia inhibitory factor (LIF), which is not expressed in guided cortical organoids, we define a cortical organoid differentiation method from human pluripotent stem cells (hPSCs) that recapitulates the expansion of a progenitor pool into the oSVZ. The oSVZ comprises progenitor cells expressing specific oRG markers such as GFAP, LIFR, and HOPX, closely matching human fetal oRG. Finally, incorporating neural crest-derived LIF-producing cortical pericytes into cortical organoids recapitulates the effects of LIF treatment. These data indicate that increasing the cellular complexity of the organoid microenvironment promotes the emergence of oRG and supports a platform to study oRG in hPSC-derived brain organoids routinely.
Assuntos
Diferenciação Celular , Ventrículos Laterais , Fator Inibidor de Leucemia , Organoides , Células-Tronco Pluripotentes , Humanos , Organoides/metabolismo , Organoides/citologia , Fator Inibidor de Leucemia/metabolismo , Fator Inibidor de Leucemia/farmacologia , Células-Tronco Pluripotentes/metabolismo , Células-Tronco Pluripotentes/citologia , Ventrículos Laterais/citologia , Ventrículos Laterais/metabolismo , Fator de Transcrição STAT3/metabolismo , Neuroglia/metabolismo , Neuroglia/citologia , Transdução de SinaisRESUMO
Adult neural stem cells (NSCs) contribute to lifelong brain plasticity. In the adult mouse ventricular-subventricular zone, NSCs are heterogeneous and, depending on their location in the niche, give rise to different subtypes of olfactory bulb (OB) interneurons. Here, we show that multiple regionally distinct NSCs, including domains that are usually quiescent, are recruited on different gestation days during pregnancy. Synchronized activation of these adult NSC pools generates transient waves of short-lived OB interneurons, especially in layers with less neurogenesis under homeostasis. Using spatial transcriptomics, we identified molecular markers of pregnancy-associated interneurons and showed that some subsets are temporarily needed for own pup recognition. Thus, pregnancy triggers transient yet behaviorally relevant neurogenesis, highlighting the physiological relevance of adult stem cell heterogeneity.
Assuntos
Interneurônios , Ventrículos Laterais , Comportamento Materno , Neurogênese , Plasticidade Neuronal , Bulbo Olfatório , Gravidez , Olfato , Animais , Feminino , Camundongos , Gravidez/fisiologia , Células-Tronco Adultas/fisiologia , Interneurônios/citologia , Interneurônios/fisiologia , Ventrículos Laterais/citologia , Ventrículos Laterais/crescimento & desenvolvimento , Células-Tronco Neurais/fisiologia , Neurogênese/fisiologia , Bulbo Olfatório/citologia , Bulbo Olfatório/crescimento & desenvolvimento , Bulbo Olfatório/metabolismo , Transcriptoma , Comportamento Materno/fisiologiaRESUMO
The insulin receptor (INSR) is an evolutionarily conserved signaling protein that regulates development and cellular metabolism. INSR signaling promotes neurogenesis in Drosophila; however, a specific role for the INSR in maintaining adult neural stem cells (NSCs) in mammals has not been investigated. We show that conditionally deleting the Insr gene in adult mouse NSCs reduces subventricular zone NSCs by â¼70% accompanied by a corresponding increase in progenitors. Insr deletion also produced hyposmia caused by aberrant olfactory bulb neurogenesis. Interestingly, hippocampal neurogenesis and hippocampal-dependent behaviors were unperturbed. Highly aggressive proneural and mesenchymal glioblastomas had high INSR/insulin-like growth factor (IGF) pathway gene expression, and isolated glioma stem cells had an aberrantly high ratio of INSR:IGF type 1 receptor. Moreover, INSR knockdown inhibited GBM tumorsphere growth. Altogether, these data demonstrate that the INSR is essential for a subset of normal NSCs, as well as for brain tumor stem cell self-renewal.
Assuntos
Células-Tronco Adultas , Ventrículos Laterais/metabolismo , Células-Tronco Neurais , Receptor de Insulina/metabolismo , Somatomedinas , Células-Tronco Adultas/citologia , Células-Tronco Adultas/metabolismo , Animais , Ventrículos Laterais/citologia , Camundongos , Células-Tronco Neurais/citologia , Células-Tronco Neurais/metabolismo , Neurogênese , Somatomedinas/metabolismoRESUMO
In the adult ventricular-subventricular zone (V-SVZ), neural stem cells (NSCs) give rise to transit-amplifying progenitor (TAP) cells. These progenitors reside in different subniche locations, implying that cell movement must accompany lineage progression, but the dynamic behaviors of adult NSCs and TAPs remain largely unexplored. Here, we performed live time-lapse imaging with computer-based image analysis of young and aged 3D V-SVZ wholemounts from transgenic mice with fluorescently distinguished NSCs and TAP cells. Young V-SVZ progenitors are highly dynamic, with regular process outgrowth and retraction and cell migration. However, these activities dramatically declined with age. An examination of single-cell RNA sequencing (RNA-seq) data revealed age-associated changes in the Rho-Rock pathway that are important for cell motility. Applying a small molecule to inhibit ROCK transformed young into old V-SVZ progenitor cell dynamic behaviors. Hence RHO-ROCK signaling is critical for normal adult NSC and TAP movement and interactions, which are compromised with age, concomitant with the loss of regenerative ability.
Assuntos
Envelhecimento , Células-Tronco Neurais/metabolismo , Nicho de Células-Tronco/fisiologia , Proteínas rho de Ligação ao GTP/metabolismo , Quinases Associadas a rho/metabolismo , Amidas/farmacologia , Animais , Movimento Celular/efeitos dos fármacos , Ventrículos Laterais/citologia , Ventrículos Laterais/metabolismo , Camundongos , Camundongos Transgênicos , Células-Tronco Neurais/citologia , Piridinas/farmacologia , Transdução de Sinais , Imagem com Lapso de Tempo , Quinases Associadas a rho/antagonistas & inibidoresRESUMO
Human MYCN is an oncogene amplified in neuroblastoma and many other tumors. Both human MYCN and mouse Mycn genes are important in embryonic brain development, but their functions in adult healthy nerve system are completely unknown. Here, with Mycn-eGFP mice and quantitative RT-PCR, we found that Mycn was expressed in specific brain regions of young adult mice, including subventricular zone (SVZ), subgranular zone (SGZ), olfactory bulb (OB), subcallosal zone (SCZ), and corpus callosum (CC). With immunohistochemistry (IHC), we found that many Mycn-expressing cells expressed neuroblast marker doublecortin (DCX) and proliferation marker Ki67. With Dcx-creER and Mki67-creER mouse lines, we fate mapped Dcx-expressing neuroblasts and Mki67-expressing proliferation cells, along with deleting Mycn from these cells in adult mice. We found that knocking out Mycn from adult neuroblasts or proliferating cells significantly reduced cells in proliferation in SVZ, SGZ, OB, SCZ, and CC. We also demonstrated that the Mycn-deficient neuroblasts in SGZ matured quicker than wild-type neuroblasts, and that Mycn-deficient proliferating cells were more likely to survive in SVZ, SGZ, OB, SCZ, and CC compared to wild type. Thus, our results demonstrate that, in addition to causing tumors in the nervous system, oncogene Mycn has a crucial function in neurogenesis and oligodendrogenesis in adult healthy brain.
Assuntos
Proteína Proto-Oncogênica N-Myc/metabolismo , Células-Tronco Neurais/metabolismo , Neurogênese/fisiologia , Oligodendroglia/metabolismo , Animais , Proliferação de Células/fisiologia , Ventrículos Laterais/citologia , Ventrículos Laterais/metabolismo , Camundongos , Camundongos Transgênicos , Proteína Proto-Oncogênica N-Myc/genética , Células-Tronco Neurais/citologia , Bulbo Olfatório/citologia , Bulbo Olfatório/metabolismo , Oligodendroglia/citologiaRESUMO
Basal progenitors (BPs), including intermediate progenitors and basal radial glia, are generated from apical radial glia and are enriched in gyrencephalic species like humans, contributing to neuronal expansion. Shortly after generation, BPs delaminate towards the subventricular zone, where they further proliferate before differentiation. Gene expression alterations involved in BP delamination and function in humans are poorly understood. Here, we study the role of LGALS3BP, so far known as a cancer biomarker, which is a secreted protein enriched in human neural progenitors (NPCs). We show that individuals with LGALS3BP de novo variants exhibit altered local gyrification, sulcal depth, surface area and thickness in their cortex. Additionally, using cerebral organoids, human fetal tissues and mice, we show that LGALS3BP regulates the position of NPCs. Single-cell RNA-sequencing and proteomics reveal that LGALS3BP-mediated mechanisms involve the extracellular matrix in NPCs' anchoring and migration within the human brain. We propose that its temporal expression influences NPCs' delamination, corticogenesis and gyrification extrinsically.
Assuntos
Antígenos de Neoplasias/metabolismo , Biomarcadores Tumorais/metabolismo , Córtex Cerebral/citologia , Vesículas Extracelulares/metabolismo , Células-Tronco Pluripotentes Induzidas/citologia , Neocórtex/citologia , Células-Tronco Neurais/citologia , Neuroglia/metabolismo , Animais , Diferenciação Celular , Córtex Cerebral/metabolismo , Feminino , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Ventrículos Laterais/citologia , Ventrículos Laterais/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Modelos Animais , Neocórtex/metabolismo , Células-Tronco Neurais/metabolismoRESUMO
Galectin-3 (Gal-3) is an evolutionarily conserved and multifunctional protein that drives inflammation in disease. Gal-3's role in the central nervous system has been less studied than in the immune system. However, recent studies show it exacerbates Alzheimer's disease and is upregulated in a large variety of brain injuries, while loss of Gal-3 function can diminish symptoms of neurodegenerative diseases such as Alzheimer's. Several novel molecular pathways for Gal-3 were recently uncovered. It is a natural ligand for TREM2 (triggering receptor expressed on myeloid cells), TLR4 (Toll-like receptor 4), and IR (insulin receptor). Gal-3 regulates a number of pathways including stimulation of bone morphogenetic protein (BMP) signaling and modulating Wnt signalling in a context-dependent manner. Gal-3 typically acts in pathology but is now known to affect subventricular zone (SVZ) neurogenesis and gliogenesis in the healthy brain. Despite its myriad interactors, Gal-3 has surprisingly specific and important functions in regulating SVZ neurogenesis in disease. Gal-1, a similar lectin often co-expressed with Gal-3, also has profound effects on brain pathology and adult neurogenesis. Remarkably, Gal-3's carbohydrate recognition domain bears structural similarity to the SARS-CoV-2 virus spike protein necessary for cell entry. Gal-3 can be targeted pharmacologically and is a valid target for several diseases involving brain inflammation. The wealth of molecular pathways now known further suggest its modulation could be therapeutically useful.
Assuntos
Galectina 3/metabolismo , Doenças do Sistema Nervoso/patologia , Neurogênese , Animais , Encéfalo/metabolismo , Encéfalo/patologia , COVID-19/metabolismo , COVID-19/patologia , Movimento Celular , Galectina 3/química , Galectina 3/genética , Humanos , Inflamação , Ventrículos Laterais/citologia , Ventrículos Laterais/crescimento & desenvolvimento , Ventrículos Laterais/patologia , Doenças do Sistema Nervoso/metabolismo , Células-Tronco Neurais/citologia , Transdução de SinaisRESUMO
The generation of new neurons in the adult brain is a currently accepted phenomenon. Over the past few decades, the subventricular zone and the hippocampal dentate gyrus have been described as the two main neurogenic niches. Neurogenic niches generate new neurons through an asymmetric division process involving several developmental steps. This process occurs throughout life in several species, including humans. These new neurons possess unique properties that contribute to the local circuitry. Despite several efforts, no other neurogenic zones have been observed in many years; the lack of observation is probably due to technical issues. However, in recent years, more brain niches have been described, once again breaking the current paradigms. Currently, a debate in the scientific community about new neurogenic areas of the brain, namely, human adult neurogenesis, is ongoing. Thus, several open questions regarding new neurogenic niches, as well as this phenomenon in adult humans, their functional relevance, and their mechanisms, remain to be answered. In this review, we discuss the literature and provide a compressive overview of the known neurogenic zones, traditional zones, and newly described zones. Additionally, we will review the regulatory roles of some molecular mechanisms, such as miRNAs, neurotrophic factors, and neurotrophins. We also join the debate on human adult neurogenesis, and we will identify similarities and differences in the literature and summarize the knowledge regarding these interesting topics.
Assuntos
Giro Denteado/citologia , Ventrículos Laterais/citologia , Neurogênese/fisiologia , Neurônios/citologia , Estriado Ventral/citologia , Adulto , Animais , Hipocampo/citologia , Humanos , Camundongos , MicroRNAs/genética , Células-Tronco Neurais/citologia , Neurogênese/genética , RatosRESUMO
Neural precursors originating in the subventricular zone (SVZ), the largest neurogenic region of the adult brain, migrate several millimeters along a restricted migratory pathway, the rostral migratory stream (RMS), toward the olfactory bulb (OB), where they differentiate into interneurons and integrate into the local neuronal circuits. Migration of SVZ-derived neuroblasts in the adult brain differs in many aspects from that in the embryonic period. Unlike in that period, postnatally-generated neuroblasts in the SVZ are able to divide during migration along the RMS, as well as they migrate independently of radial glia. The homophilic mode of migration, i.e., using each other to move, is typical for neuroblast movement in the RMS. In addition, it has recently been demonstrated that specifically-arranged blood vessels navigate SVZ-derived neuroblasts to the OB and provide signals which promote migration. Here we review the development of vasculature in the presumptive neurogenic region of the rodent brain during the embryonic period as well as the development of the vascular scaffold guiding neuroblast migration in the postnatal period, and the significance of blood vessel reorganization during the early postnatal period for proper migration of RMS neuroblasts in adulthood.
Assuntos
Encéfalo/irrigação sanguínea , Ventrículos Laterais/fisiologia , Neovascularização Fisiológica/fisiologia , Células-Tronco Neurais/fisiologia , Neurogênese/fisiologia , Bulbo Olfatório/fisiologia , Animais , Vasos Sanguíneos/metabolismo , Encéfalo/embriologia , Movimento Celular/fisiologia , Ventrículos Laterais/citologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos ICR , Neurônios/citologia , Neurônios/fisiologia , Bulbo Olfatório/citologiaRESUMO
The ventricular-subventricular zone (V-SVZ), on the walls of the lateral ventricles, harbors the largest neurogenic niche in the adult mouse brain. Previous work has shown that neural stem/progenitor cells (NSPCs) in different locations within the V-SVZ produce different subtypes of new neurons for the olfactory bulb. The molecular signatures that underlie this regional heterogeneity remain largely unknown. Here, we present a single-cell RNA-sequencing dataset of the adult mouse V-SVZ revealing two populations of NSPCs that reside in largely non-overlapping domains in either the dorsal or ventral V-SVZ. These regional differences in gene expression were further validated using a single-nucleus RNA-sequencing reference dataset of regionally microdissected domains of the V-SVZ and by immunocytochemistry and RNAscope localization. We also identify two subpopulations of young neurons that have gene expression profiles consistent with a dorsal or ventral origin. Interestingly, a subset of genes are dynamically expressed, but maintained, in the ventral or dorsal lineages. The study provides novel markers and territories to understand the region-specific regulation of adult neurogenesis.
Nerve cells, or neurons, are the central building blocks of brain circuits. Their damage, death or loss of function leads to cognitive decline. Neural stem/progenitor cells (NSPCs) first appear during embryo development, generating most of the neurons found in the nervous system. However, the adult brain retains a small subpopulation of NSPCs, which in some species are an important source of new neurons throughout life. In the adult mouse brain the largest population of NSPCs, known as B cells, is found in an area called the ventricular-subventricular zone (V-SVZ). These V-SVZ B cells have properties of specialized support cells known as astrocytes, but they can also divide and generate intermediate 'progenitor cells' called C cells. These, in turn, divide to generate large numbers of young 'A cells' neurons that undertake a long and complex migration from V-SVZ to the olfactory bulb, the first relay in the central nervous system for the processing of smells. Depending on their location in the V-SVZ, B cells can generate different kinds of neurons, leading to at least ten subtypes of neurons. Why this is the case is still poorly understood. To examine this question, Cebrián-Silla, Nascimento, Redmond, Mansky et al. determined which genes were expressed in B, C and A cells from different parts of the V-SVZ. While cells within each of these populations had different expression patterns, those that originated in the same V-SVZ locations shared a set of genes, many of which associated with regional specification in the developing brain. Some, however, were intriguingly linked to hormonal regulation. Salient differences between B cells depended on whether the cells originated closer to the top ('dorsal' position) or to the bottom of the brain ('ventral' position). This information was used to stain slices of mouse brains for the RNA and proteins produced by these genes in different regions. These experiments revealed dorsal and ventral territories containing B cells with distinct 'gene expression'. This study highlights the heterogeneity of NSPCs, revealing key molecular differences among B cells in dorsal and ventral areas of the V-SVZ and reinforcing the concept that the location of NSPCs determines the types of neuron they generate. Furthermore, the birth of specific types of neurons from B cells that are so strictly localized highlights the importance of neuronal migration to ensure that young neurons with specific properties reach their appropriate destination in the olfactory bulb. The work by Cebrián-Silla, Nascimento, Redmond, Mansky et al. has identified sets of genes that are differentially expressed in dorsal and ventral regions which may contribute to regional regulation. Furthering the understanding of how adult NSPCs differ according to their location will help determine how various neuron types emerge in the adult brain.
Assuntos
Ventrículos Laterais/citologia , Células-Tronco Neurais/metabolismo , Neurogênese/genética , Transcriptoma/genética , Animais , Feminino , Masculino , Camundongos , Camundongos Transgênicos , Microdissecção , Células-Tronco Neurais/química , Células-Tronco Neurais/citologia , Análise de Célula ÚnicaRESUMO
Neural and oligodendrocyte precursor cells (NPCs and OPCs) in the subventricular zone (SVZ) of the brain contribute to oligodendrogenesis throughout life, in part due to direct regulation by chemokines. The role of the chemokine fractalkine is well established in microglia; however, the effect of fractalkine on SVZ precursor cells is unknown. We show that murine SVZ NPCs and OPCs express the fractalkine receptor (CX3CR1) and bind fractalkine. Exogenous fractalkine directly enhances OPC and oligodendrocyte genesis from SVZ NPCs in vitro. Infusion of fractalkine into the lateral ventricle of adult NPC lineage-tracing mice leads to increased newborn OPC and oligodendrocyte formation in vivo. We also show that OPCs secrete fractalkine and that inhibition of endogenous fractalkine signaling reduces oligodendrocyte formation in vitro. Finally, we show that fractalkine signaling regulates oligodendrogenesis in cerebellar slices ex vivo. In summary, we demonstrate a novel role for fractalkine signaling in regulating oligodendrocyte genesis from postnatal CNS precursor cells.
Assuntos
Receptor 1 de Quimiocina CX3C/metabolismo , Quimiocina CX3CL1/metabolismo , Ventrículos Laterais/metabolismo , Células Precursoras de Oligodendrócitos/metabolismo , Oligodendroglia/metabolismo , Transdução de Sinais , Animais , Receptor 1 de Quimiocina CX3C/genética , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/genética , Células Cultivadas , Quimiocina CX3CL1/farmacologia , Expressão Gênica/efeitos dos fármacos , Ventrículos Laterais/citologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Microscopia Confocal , Células Precursoras de Oligodendrócitos/citologia , Fator de Transcrição 2 de Oligodendrócitos/genética , Fator de Transcrição 2 de Oligodendrócitos/metabolismo , Oligodendroglia/citologia , Fatores de Transcrição SOXB1/genética , Fatores de Transcrição SOXB1/metabolismoRESUMO
We studied the participation of JNK and p53 in the realization of the growth potential of different types of progenitors of the subventricular zone of mouse brain and secretion of neurotrophins by glial cells. The stimulating role of these signaling molecules in mitotic activity and specialization of multipotent neural stem cells was shown. It was found that JNK and p53 do not participate in the regulation of committed neuronal progenitor cells (clonogenic PSA-NCAM+ cells). A dependence of neurotrophic growth factors in individual populations of neuroglia on activity of these protein kinase and transcription factor was revealed. The role of JNK and p53 in astrocytes consists in stimulation of their secretion, and in microglial cells, on the contrary, in its inhibition. The secretory neurotrophic function of oligodendrogliocytes is not associated with JNK and p53 activity.
Assuntos
Astrócitos/metabolismo , MAP Quinase Quinase 4/genética , Células-Tronco Multipotentes/metabolismo , Células-Tronco Neurais/metabolismo , Neuroglia/metabolismo , Proteína Supressora de Tumor p53/genética , Animais , Astrócitos/citologia , Astrócitos/efeitos dos fármacos , Benzotiazóis/farmacologia , Antígeno CD56/genética , Antígeno CD56/metabolismo , Meios de Cultivo Condicionados/farmacologia , Regulação da Expressão Gênica , Ventrículos Laterais/citologia , Ventrículos Laterais/efeitos dos fármacos , Ventrículos Laterais/metabolismo , MAP Quinase Quinase 4/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Células-Tronco Multipotentes/citologia , Células-Tronco Multipotentes/efeitos dos fármacos , Fatores de Crescimento Neural/biossíntese , Fatores de Crescimento Neural/genética , Moléculas de Adesão de Célula Nervosa/genética , Moléculas de Adesão de Célula Nervosa/metabolismo , Células-Tronco Neurais/citologia , Células-Tronco Neurais/efeitos dos fármacos , Neuroglia/citologia , Neuroglia/efeitos dos fármacos , Transdução de Sinais , Tolueno/análogos & derivados , Tolueno/farmacologia , Proteína Supressora de Tumor p53/metabolismoRESUMO
Quiescent neural stem cells (NSCs) in the adult mouse ventricular-subventricular zone (V-SVZ) undergo activation to generate neurons and some glia. Here we show that platelet-derived growth factor receptor beta (PDGFRß) is expressed by adult V-SVZ NSCs that generate olfactory bulb interneurons and glia. Selective deletion of PDGFRß in adult V-SVZ NSCs leads to their release from quiescence, uncovering gliogenic domains for different glial cell types. These domains are also recruited upon injury. We identify an intraventricular oligodendrocyte progenitor derived from NSCs inside the brain ventricles that contacts supraependymal axons. Together, our findings reveal that the adult V-SVZ contains spatial domains for gliogenesis, in addition to those for neurogenesis. These gliogenic NSC domains tend to be quiescent under homeostasis and may contribute to brain plasticity.