RESUMO
Neural stem cells (NSCs) in the adult brain transit from the quiescent state to proliferation to produce new neurons. The mechanisms regulating this transition in freely behaving animals are, however, poorly understood. We customized in vivo imaging protocols to follow NSCs for several days up to months, observing their activation kinetics in freely behaving mice. Strikingly, NSC division is more frequent during daylight and is inhibited by darkness-induced melatonin signaling. The inhibition of melatonin receptors affected intracellular Ca2+ dynamics and promoted NSC activation. We further discovered a Ca2+ signature of quiescent versus activated NSCs and showed that several microenvironmental signals converge on intracellular Ca2+ pathways to regulate NSC quiescence and activation. In vivo NSC-specific optogenetic modulation of Ca2+ fluxes to mimic quiescent-state-like Ca2+ dynamics in freely behaving mice blocked NSC activation and maintained their quiescence, pointing to the regulatory mechanisms mediating NSC activation in freely behaving animals.
Assuntos
Células-Tronco Adultas/metabolismo , Cálcio/metabolismo , Ritmo Circadiano , Espaço Intracelular/metabolismo , Células-Tronco Neurais/metabolismo , Células-Tronco Adultas/citologia , Células-Tronco Adultas/efeitos dos fármacos , Animais , Astrócitos/efeitos dos fármacos , Astrócitos/metabolismo , Comportamento Animal/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Ritmo Circadiano/efeitos dos fármacos , Citosol/metabolismo , Fator de Crescimento Epidérmico/farmacologia , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Melatonina/metabolismo , Camundongos , Células-Tronco Neurais/citologia , Células-Tronco Neurais/efeitos dos fármacos , Optogenética , Transdução de Sinais/efeitos dos fármacos , Triptaminas/farmacologiaRESUMO
We report that astrocytic insulin signaling co-regulates hypothalamic glucose sensing and systemic glucose metabolism. Postnatal ablation of insulin receptors (IRs) in glial fibrillary acidic protein (GFAP)-expressing cells affects hypothalamic astrocyte morphology, mitochondrial function, and circuit connectivity. Accordingly, astrocytic IR ablation reduces glucose-induced activation of hypothalamic pro-opio-melanocortin (POMC) neurons and impairs physiological responses to changes in glucose availability. Hypothalamus-specific knockout of astrocytic IRs, as well as postnatal ablation by targeting glutamate aspartate transporter (GLAST)-expressing cells, replicates such alterations. A normal response to altering directly CNS glucose levels in mice lacking astrocytic IRs indicates a role in glucose transport across the blood-brain barrier (BBB). This was confirmed in vivo in GFAP-IR KO mice by using positron emission tomography and glucose monitoring in cerebral spinal fluid. We conclude that insulin signaling in hypothalamic astrocytes co-controls CNS glucose sensing and systemic glucose metabolism via regulation of glucose uptake across the BBB.
Assuntos
Astrócitos/metabolismo , Glucose/metabolismo , Hipotálamo/metabolismo , Insulina/metabolismo , Transdução de Sinais , Sistema X-AG de Transporte de Aminoácidos/genética , Sistema X-AG de Transporte de Aminoácidos/metabolismo , Animais , Barreira Hematoencefálica , Retículo Endoplasmático/metabolismo , Proteína Glial Fibrilar Ácida/genética , Proteína Glial Fibrilar Ácida/metabolismo , Homeostase , Camundongos , Mitocôndrias/metabolismo , Neurônios/citologia , Neurônios/metabolismo , Pró-Opiomelanocortina/metabolismo , Receptor de Insulina/genética , Receptor de Insulina/metabolismoRESUMO
Posttranscriptional gene expression including splicing, RNA transport, translation, and RNA decay provides an important regulatory layer in many if not all molecular pathways. Research in the last decades has positioned RNA-binding proteins (RBPs) right in the center of posttranscriptional gene regulation. Here, we propose interdependent networks of RBPs to regulate complex pathways within the central nervous system (CNS). These are involved in multiple aspects of neuronal development and functioning, including higher cognition. Therefore, it is not sufficient to unravel the individual contribution of a single RBP and its consequences but rather to study and understand the tight interplay between different RBPs. In this review, we summarize recent findings in the field of RBP biology and discuss the complex interplay between different RBPs. Second, we emphasize the underlying dynamics within an RBP network and how this might regulate key processes such as neurogenesis, synaptic transmission, and synaptic plasticity. Importantly, we envision that dysfunction of specific RBPs could lead to perturbation within the RBP network. This would have direct and indirect (compensatory) effects in mRNA binding and translational control leading to global changes in cellular expression programs in general and in synaptic plasticity in particular. Therefore, we focus on RBP dysfunction and how this might cause neuropsychiatric and neurodegenerative disorders. Based on recent findings, we propose that alterations in the entire regulatory RBP network might account for phenotypic dysfunctions observed in complex diseases including neurodegeneration, epilepsy, and autism spectrum disorders.
Assuntos
Encefalopatias/metabolismo , Encéfalo/metabolismo , Proteínas de Ligação a RNA/metabolismo , Animais , HumanosRESUMO
Adult stem cells are important for tissue turnover and regeneration. However, in most adult systems it remains elusive how stem cells assume different functional states and support spatially patterned tissue architecture. Here, we dissected the diversity of neural stem cells in the adult zebrafish brain, an organ that is characterized by pronounced zonation and high regenerative capacity. We combined single-cell transcriptomics of dissected brain regions with massively parallel lineage tracing and in vivo RNA metabolic labeling to analyze the regulation of neural stem cells in space and time. We detected a large diversity of neural stem cells, with some subtypes being restricted to a single brain region, while others were found globally across the brain. Global stem cell states are linked to neurogenic differentiation, with different states being involved in proliferative and non-proliferative differentiation. Our work reveals principles of adult stem cell organization and establishes a resource for the functional manipulation of neural stem cell subtypes.
Assuntos
Células-Tronco Adultas , Células-Tronco Neurais , Animais , Peixe-Zebra/fisiologia , Células-Tronco Neurais/metabolismo , Neurogênese , Encéfalo , Diferenciação CelularRESUMO
Regulation of adult neural stem cell (NSC) number is critical for lifelong neurogenesis. Here, we identified a post-transcriptional control mechanism, centered around the microRNA 204 (miR-204), to control the maintenance of quiescent (q)NSCs. miR-204 regulates a spectrum of transcripts involved in cell cycle regulation, neuronal migration, and differentiation in qNSCs. Importantly, inhibition of miR-204 function reduced the number of qNSCs in the subependymal zone (SEZ) by inducing pre-mature activation and differentiation of NSCs without changing their neurogenic potential. Strikingly, we identified the choroid plexus of the mouse lateral ventricle as the major source of miR-204 that is released into the cerebrospinal fluid to control number of NSCs within the SEZ. Taken together, our results describe a novel mechanism to maintain adult somatic stem cells by a niche-specific miRNA repressing activation and differentiation of stem cells.
Assuntos
Plexo Corióideo/química , MicroRNAs/genética , Células-Tronco Neurais/citologia , Adulto , Animais , Ciclo Celular , Diferenciação Celular , Movimento Celular , Feminino , Regulação da Expressão Gênica , Humanos , Masculino , Camundongos , MicroRNAs/líquido cefalorraquidiano , Pessoa de Meia-Idade , Células-Tronco Neurais/química , Nicho de Células-TroncoRESUMO
Multiciliated cells are abundant in the epithelial surface of different tissues, including cells lining the walls of the lateral ventricles in the brain and the airway epithelium. Their main role is to control fluid flow and defects in their differentiation are implicated in many human disorders, such as hydrocephalus, accompanied by defects in adult neurogenesis and mucociliary disorder in the airway system. Here we show that Mcidas, which is mutated in human mucociliary clearance disorder, and GemC1 (Gmnc or Lynkeas), previously implicated in cell cycle progression, are key regulators of multiciliated ependymal cell generation in the mouse brain. Overexpression and knockdown experiments show that Mcidas and GemC1 are sufficient and necessary for cell fate commitment and differentiation of radial glial cells to multiciliated ependymal cells. Furthermore, we show that GemC1 and Mcidas operate in hierarchical order, upstream of Foxj1 and c-Myb transcription factors, which are known regulators of ependymal cell generation, and that Notch signaling inhibits GemC1 and Mcidas function. Our results suggest that Mcidas and GemC1 are key players in the generation of multiciliated ependymal cells of the adult neurogenic niche.
Assuntos
Proteínas de Transporte/metabolismo , Proteínas de Ciclo Celular/metabolismo , Epêndima/citologia , Células Ependimogliais/citologia , Células Ependimogliais/metabolismo , Neurogênese , Proteínas Nucleares/metabolismo , Animais , Proteínas de Transporte/genética , Proteínas de Ciclo Celular/genética , Epêndima/metabolismo , Fatores de Transcrição Forkhead/metabolismo , Camundongos , Proteínas Nucleares/genética , Proteínas Proto-Oncogênicas c-myb/metabolismo , Receptores Notch/metabolismo , Transdução de Sinais , Células-Tronco/citologia , Células-Tronco/metabolismoRESUMO
Aging leads to adverse outcomes after traumatic brain injury. The mechanisms underlying these defects, however, are not yet clear. In this study, we found that astrocytes in the aged post-traumatic cerebral cortex develop a significantly reduced proliferative response, resulting in reduced astrocyte numbers in the penumbra. Moreover, experiments of reactive astrocytes in vitro reveal that their diminished proliferation is due to an age-related switch in the division mode with reduced cell-cycle re-entry rather than changes in cell-cycle length. Notably, reactive astrocytes in vivo and in vitro become refractory to stimuli increasing their proliferation during aging, such as Sonic hedgehog signaling. These data demonstrate for the first time that age-dependent, most likely intrinsic changes in the proliferative program of reactive astrocytes result in their severely hampered proliferative response to traumatic injury thereby affecting astrocyte homeostasis.
Assuntos
Envelhecimento/fisiologia , Astrócitos/fisiologia , Lesões Encefálicas/fisiopatologia , Proliferação de Células/fisiologia , Homeostase/fisiologia , Córtex Somatossensorial/fisiopatologia , Envelhecimento/patologia , Animais , Astrócitos/patologia , Lesões Encefálicas/patologia , Células Cultivadas , Modelos Animais de Doenças , Gliose/patologia , Gliose/fisiopatologia , Proteínas Hedgehog/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Transdução de Sinais , Córtex Somatossensorial/lesões , Córtex Somatossensorial/patologia , Ferimentos PerfurantesRESUMO
During development of the CNS, stem and progenitor cell proliferation, cell fate designation, and patterning decisions are tightly regulated by interdependent networks of key transcriptional regulators. In a genetic approach we analyzed divergent functionality of the PAI and RED sub-domains of the Pax6 Paired domain (PD) during progenitor zone formation, motor and interneuron development, and peripheral connectivity at distinct levels within the neural tube: within the hindbrain, mutation of the PAI sub-domain severely affected patterning of the p3 and pMN domains and establishment of the corresponding motor neurons. Exit point designation of hypoglossal axons was disturbed in embryos harboring either mutations in the PD sub-domains or containing a functional Pax6 Null allele. At brachial spinal levels, we propose a selective involvement of the PAI sub-domain during patterning of ventral p2 and pMN domains, critically disturbing generation of specific motor neuron subtypes and increasing V2 interneuron numbers. Our findings present a novel aspect of how Pax6 not only utilizes its modular structure to perform distinct functions via its paired and homeodomain. Individual sub-domains can exert distinct functions, generating a new level of complexity for transcriptional regulation by one single transcription factor not only in dorso-ventral, but also rostro-caudal neural tube patterning.
Assuntos
Proteínas do Olho/genética , Proteínas de Homeodomínio/genética , Tubo Neural/embriologia , Fatores de Transcrição Box Pareados/genética , Sistema Nervoso Periférico/embriologia , Proteínas Repressoras/genética , Alelos , Animais , Axônios/metabolismo , Axônios/fisiologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Padronização Corporal , Linhagem da Célula , Proliferação de Células , Proteínas de Ligação a DNA/genética , Proteínas do Olho/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Genótipo , Proteínas de Fluorescência Verde/metabolismo , Proteínas de Homeodomínio/fisiologia , Imuno-Histoquímica , Hibridização In Situ , Interneurônios/metabolismo , Camundongos , Neurônios Motores/metabolismo , Mutação , Proteínas do Tecido Nervoso/genética , Fator de Transcrição PAX6 , Fatores de Transcrição Box Pareados/fisiologia , Fenótipo , Estrutura Terciária de Proteína , Proteínas Repressoras/fisiologia , Rombencéfalo/metabolismo , Células-Tronco/citologia , Fatores de Transcrição/genéticaRESUMO
Astrocytes are the most abundant cell type of the central nervous system and cover a broad range of functionalities. We report here the generation of a novel monoclonal antibody, anti-astrocyte cell surface antigen-2 (Anti-ACSA-2). Flow cytometry, immunohistochemistry and immunocytochemistry revealed that Anti-ACSA-2 reacted specifically with a not yet identified glycosylated surface molecule of murine astrocytes at all developmental stages. It did not show any labeling of non-astroglial cells such as neurons, oligodendrocytes, NG2+ cells, microglia, endothelial cells, leukocytes, or erythrocytes. Co-labeling studies of GLAST and ACSA-2 showed largely overlapping expression. However, there were also notable differences in protein expression levels and frequencies of single-positive subpopulations of cells in some regions of the CNS such as cerebellum, most prominently at early postnatal stages. In the neurogenic niches, the dentate gyrus of the hippocampus and the subventricular zone (SVZ), again a general overlap with slight differences in expression levels were observed. ACSA-2 was unlike GLAST not sensitive to papain-based tissue dissociation and allowed for a highly effective, acute, specific, and prospective purification of viable astrocytes based on a new rapid sorting procedure using Anti-ACSA-2 directly coupled to superparamagnetic MicroBeads. In conclusion, ACSA-2 appears to be a new surface marker for astrocytes, radial glia, neural stem cells and bipotent glial progenitor cells which opens up the possibility of further dissecting the characteristics of astroglial subpopulations and lineages.
Assuntos
Anticorpos Monoclonais/imunologia , Antígenos de Superfície/análise , Antígenos de Superfície/imunologia , Astrócitos/citologia , Astrócitos/imunologia , Separação Imunomagnética/métodos , Animais , Animais Recém-Nascidos , Especificidade de Anticorpos , Antígenos de Superfície/metabolismo , Encéfalo/citologia , Encéfalo/crescimento & desenvolvimento , Células Cultivadas , Células Endoteliais/citologia , Células Endoteliais/imunologia , Eritrócitos/citologia , Eritrócitos/metabolismo , Transportador 1 de Aminoácido Excitatório/análise , Leucócitos/citologia , Leucócitos/imunologia , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microglia/citologia , Microglia/imunologia , Células-Tronco Neurais/imunologia , Neurônios/citologia , Neurônios/metabolismo , Oligodendroglia/citologia , Oligodendroglia/imunologia , Ratos WistarRESUMO
Histone posttranslational modifications and histone variants control the epigenetic regulation of gene expression and affect a wide variety of biological processes. A complex pattern of such modifications and variants defines the identity of cells within complex organ systems and can therefore be used to characterize cells at a molecular level. However, their detection and identification in situ has been limited so far due to lack of specificity, selectivity, and availability of antihistone antibodies. Here, we describe a novel MALDI imaging MS based workflow, which enables us to detect and characterize histones by their intact mass and their correlation with cytological properties of the tissue using novel statistical and image analysis tools. The workflow allows us to characterize the in situ distribution of the major histone variants and their modification in the mouse brain. This new analysis tool is particularly useful for the investigation of expression patterns of the linker histone H1 variants for which suitable antibodies are so far not available.
Assuntos
Encéfalo/metabolismo , Cromatina/química , Epigênese Genética , Histonas/genética , Processamento de Proteína Pós-Traducional , Acetilação , Animais , Encéfalo/ultraestrutura , Química Encefálica , Cromatina/metabolismo , Histonas/metabolismo , Masculino , Metilação , Camundongos , Imagem Molecular/métodos , Fosforilação , Análise de Componente Principal , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Biologia de Sistemas/instrumentação , Biologia de Sistemas/métodosRESUMO
To achieve adequate organ development and size, cell proliferation and differentiation have to be tightly regulated and coordinated. The transcription factor Pax6 regulates patterning, neurogenesis and proliferation in forebrain development. The molecular basis of this regulation is not well understood. As the bipartite DNA-binding paired domain of Pax6 regulates forebrain development, we examined mice with point mutations in its individual DNA-binding subdomains PAI (Pax6(Leca4), N50K) and RED (Pax6(Leca2), R128C). This revealed distinct roles in regulating proliferation in the developing cerebral cortex, with the PAI and RED subdomain mutations reducing and increasing, respectively, the number of mitoses. Conversely, neurogenesis was affected only by the PAI subdomain mutation, phenocopying the neurogenic defects observed in full Pax6 mutants. Genome-wide expression profiling identified molecularly discrete signatures of Pax6(Leca4) and Pax6(Leca2) mutations. Comparison to Pax6 targets identified by chromatin immunoprecipitation led to the identification and functional characterization of distinct DNA motifs in the promoters of target genes dysregulated in the Pax6(Leca2) or Pax6(Leca4) mutants, further supporting the distinct regulatory functions of the DNA-binding subdomains. Thus, Pax6 achieves its key roles in the developing forebrain by utilizing particular subdomains to coordinate patterning, neurogenesis and proliferation simultaneously.
Assuntos
Proliferação de Células , Proteínas do Olho/química , Proteínas do Olho/genética , Proteínas do Olho/fisiologia , Proteínas de Homeodomínio/química , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/fisiologia , Neurogênese/genética , Fatores de Transcrição Box Pareados/química , Fatores de Transcrição Box Pareados/genética , Fatores de Transcrição Box Pareados/fisiologia , Proteínas Repressoras/química , Proteínas Repressoras/genética , Proteínas Repressoras/fisiologia , Animais , Animais Geneticamente Modificados , Padronização Corporal/genética , Padronização Corporal/fisiologia , Embrião de Mamíferos , Proteínas do Olho/metabolismo , Proteínas de Homeodomínio/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Modelos Biológicos , Mutagênese Sítio-Dirigida , Fator de Transcrição PAX6 , Fatores de Transcrição Box Pareados/metabolismo , Prosencéfalo/embriologia , Prosencéfalo/metabolismo , Mapeamento de Interação de Proteínas , Estrutura Terciária de Proteína/genética , Estrutura Terciária de Proteína/fisiologia , Proteínas Repressoras/metabolismo , Transdução de Sinais/genéticaRESUMO
Neuronal differentiation relies on a set of interconnected molecular events to achieve the differentiation of pan-neuronal hallmarks, together with neuronal subtype-specific features. Here, we propose a conceptual framework for these events, based on recent findings. This framework encompasses a dimension in time during development, progressing from early master regulators to later expressed effector genes and terminal selector genes. As a horizontal intersection, we propose the action of permissive fate determinants that are critical in allowing progression through the above transcriptional phases. Typically, these are widely expressed and often interact with the chromatin remodeling machinery. We conclude by discussing this model in the context of the direct fate conversion of various somatic cells into neurons.
Assuntos
Sistema Nervoso Central/citologia , Sistema Nervoso Central/metabolismo , Neurogênese , Neurônios/citologia , Animais , Linhagem da Célula , Humanos , Transcrição GênicaRESUMO
In the adult mammalian brain, neurogenesis is restricted to few regions, while gliogenesis continues in a wide-spread manner. Here we discuss our knowledge of extrinsic and intrinsic factors regulating neuro- and gliogenesis in the adult brain and propose a model of fate specification identifying the states of easiest transition between glio- and neurogenesis, highlighting the unique mechanisms stabilising the neural stem cell state. The model also encompasses the fate alterations achieved by direct reprogramming, and hence addresses a novel avenue for repair, namely eliciting neurogenesis from glial cells outside the neurogenic niches.
Assuntos
Encéfalo/citologia , Linhagem da Célula , Neurogênese , Neuroglia/citologia , Adulto , Animais , Humanos , Modelos Biológicos , Nicho de Células-TroncoRESUMO
Successful brain development requires tight regulation of sequential symmetric and asymmetric cell division. Although Pax6 is known to exert multiple roles in the developing nervous system, its role in the regulation of cell division is unknown. Here, we demonstrate profound alterations in the orientation and mode of cell division in the cerebral cortex of mice deficient in Pax6 function (Pax6(Sey/Sey)) or after acute induced deletion of Pax6. Live imaging revealed an increase in non-vertical cellular cleavage planes, resulting in an increased number of progenitors with unequal inheritance of the apical membrane domain and adherens junctions in the absence of Pax6 function. This phenotype appears to be mediated by the direct Pax6 target Spag5, a microtubule-associated protein, reduced levels of which result in the replication of the Pax6 phenotype of altered cell division orientation. In addition, lack of Pax6 also results in premature delamination of progenitor cells from the apical surface due to an overall decrease in proteins mediating anchoring at the ventricular surface. Moreover, continuous long-term imaging in vitro revealed that Pax6-deficient progenitors generate daughter cells with asymmetric fates at higher frequencies. These data demonstrate a cell-autonomous role for Pax6 in regulating the mode of cell division independently of apicobasal polarity and cell-cell interactions. Taken together, our work reveals several direct effects that the transcription factor Pax6 has on the machinery that mediates the orientation and mode of cell division.
Assuntos
Divisão Celular/fisiologia , Polaridade Celular/fisiologia , Córtex Cerebral/citologia , Córtex Cerebral/embriologia , Proteínas do Olho/metabolismo , Proteínas de Homeodomínio/metabolismo , Fatores de Transcrição Box Pareados/metabolismo , Proteínas Repressoras/metabolismo , Células-Tronco/fisiologia , Análise de Variância , Animais , Proteínas de Ciclo Celular , Imunoprecipitação da Cromatina , Primers do DNA/genética , Eletroporação , Feminino , Imuno-Histoquímica , Luciferases , Camundongos , Fator de Transcrição PAX6 , Reação em Cadeia da Polimerase/métodos , GravidezRESUMO
Spatially resolved transcriptomics has revolutionized RNA studies by aligning RNA abundance with tissue structure, enabling direct comparisons between histology and gene expression. Traditional approaches to identifying signature genes often involve preliminary data grouping, which can overlook subtle expression patterns in complex tissues. We present Spatial Gradient Screening, an algorithm which facilitates the supervised detection of histology-associated gene expression patterns without prior data grouping. Utilizing spatial transcriptomic data along with single-cell deconvolution from injured mouse cortex, and TCR-seq data from brain tumors, we compare our methodology to standard differential gene expression analysis. Our findings illustrate both the advantages and limitations of cluster-free detection of gene expression, offering more profound insights into the spatial architecture of transcriptomes. The algorithm is embedded in SPATA2, an open-source framework written in R, which provides a comprehensive set of tools for investigating gene expression within tissue.
Assuntos
Algoritmos , Perfilação da Expressão Gênica , Transcriptoma , Animais , Camundongos , Perfilação da Expressão Gênica/métodos , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/metabolismo , Humanos , Análise de Célula Única/métodosRESUMO
Traumatic brain injury leads to a highly orchestrated immune- and glial cell response partially responsible for long-lasting disability and the development of secondary neurodegenerative diseases. A holistic understanding of the mechanisms controlling the responses of specific cell types and their crosstalk is required to develop an efficient strategy for better regeneration. Here, we combine spatial and single-cell transcriptomics to chart the transcriptomic signature of the injured male murine cerebral cortex, and identify specific states of different glial cells contributing to this signature. Interestingly, distinct glial cells share a large fraction of injury-regulated genes, including inflammatory programs downstream of the innate immune-associated pathways Cxcr3 and Tlr1/2. Systemic manipulation of these pathways decreases the reactivity state of glial cells associated with poor regeneration. The functional relevance of the discovered shared signature of glial cells highlights the importance of our resource enabling comprehensive analysis of early events after brain injury.
Assuntos
Lesões Encefálicas , Ferimentos Perfurantes , Animais , Camundongos , Masculino , Proteína Glial Fibrilar Ácida/metabolismo , Neuroglia/metabolismo , Lesões Encefálicas/metabolismo , Córtex Cerebral/metabolismo , Ferimentos Perfurantes/complicações , Ferimentos Perfurantes/metabolismoRESUMO
Acute brain injuries evoke various response cascades directing the formation of the glial scar. Here, we report that acute lesions associated with hemorrhagic injuries trigger a re-programming of oligodendrocytes. Single-cell RNA sequencing highlighted a subpopulation of oligodendrocytes activating astroglial genes after acute brain injuries. By using PLP-DsRed1/GFAP-EGFP and PLP-EGFPmem/GFAP-mRFP1 transgenic mice, we visualized this population of oligodendrocytes that we termed AO cells based on their concomitant activity of astro- and oligodendroglial genes. By fate mapping using PLP- and GFAP-split Cre complementation and repeated chronic in vivo imaging with two-photon laser-scanning microscopy, we observed the conversion of oligodendrocytes into astrocytes via the AO cell stage. Such conversion was promoted by local injection of IL-6 and was diminished by IL-6 receptor-neutralizing antibody as well as by inhibiting microglial activation with minocycline. In summary, our findings highlight the plastic potential of oligodendrocytes in acute brain trauma due to microglia-derived IL-6.
Assuntos
Astrócitos , Lesões Encefálicas , Camundongos , Animais , Interleucina-6 , Proteína Glial Fibrilar Ácida/genética , Oligodendroglia , Camundongos TransgênicosRESUMO
The glial environment influences neurological disease progression, yet much of our knowledge still relies on preclinical animal studies, especially regarding astrocyte heterogeneity. In murine models of traumatic brain injury, beneficial functions of proliferating reactive astrocytes on disease outcome have been unraveled, but little is known regarding if and when they are present in human brain pathology. Here we examined a broad spectrum of pathologies with and without intracerebral hemorrhage and found a striking correlation between lesions involving blood-brain barrier rupture and astrocyte proliferation that was further corroborated in an assay probing for neural stem cell potential. Most importantly, proteomic analysis unraveled a crucial signaling pathway regulating this astrocyte plasticity with GALECTIN3 as a novel marker for proliferating astrocytes and the GALECTIN3-binding protein LGALS3BP as a functional hub mediating astrocyte proliferation and neurosphere formation. Taken together, this work identifies a therapeutically relevant astrocyte response and their molecular regulators in different pathologies affecting the human cerebral cortex.
Assuntos
Astrócitos , Células-Tronco Neurais , Humanos , Camundongos , Animais , Astrócitos/patologia , Proteômica , Encéfalo , Sistema Nervoso CentralRESUMO
Reactive glia, including astroglia and oligodendrocyte progenitors (OPCs) are at the core of the reaction to injury in the mammalian brain with initially beneficial and later partially adverse functions such as scar formation. Given the different glial composition in the adult zebrafish brain with radial ependymoglia but no parenchymal astrocytes, we examined the glial response to an invasive stab wound injury model in the adult zebrafish telencephalon. Strikingly, already a few days after injury the wound was closed without any scar tissue. Similar to mammals, microglia cells reacted first and accumulated close to the injury site, while neither GFAP+ radial ependymoglia nor adult OPCs were recruited to the injury site. Moreover, OPCs failed to increase their proliferation after this injury, while the number of proliferating GFAP+ glia was increased until 7 days after injury. Importantly, neurogenesis was also increased after injury, generating additional neurons recruited to the parenchyma which survived for several months. Thus, these data suggest that the specific glial environment in the adult zebrafish telencephalon is not only permissive for long-term neuronal survival, but avoids scar formation. Invasive injury in the adult zebrafish telencephalon may therefore provide a useful model to untangle the molecular mechanisms involved in these beneficial glial reactions.
Assuntos
Modelos Animais de Doenças , Gliose/etiologia , Telencéfalo/lesões , Ferimentos Perfurantes/complicações , Aminoácidos , Animais , Animais Geneticamente Modificados , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Bromodesoxiuridina/metabolismo , Proliferação de Células , Regulação da Expressão Gênica/fisiologia , Proteína Glial Fibrilar Ácida/genética , Proteínas de Fluorescência Verde/genética , Microglia/classificação , Microglia/patologia , Proteínas do Tecido Nervoso/genética , Neurogênese , Fator de Transcrição 2 de Oligodendrócitos , Proteína Proto-Oncogênica c-fli-1/genética , Ferimentos Perfurantes/patologia , Peixe-Zebra , Proteínas de Peixe-Zebra/genéticaRESUMO
A new study finds the spliceosome protein SNRNP70 in cytoplasmic RNA granules in zebrafish motoneurons. Intriguingly, cytoplasmic SNRNP70 is essential for functional neuromuscular junctions, possibly due to a role in alternative splicing of z+agrin mRNA.