Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 13.785
Filtrar
1.
Life Sci ; 231: 116517, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31150684

RESUMO

Our previous study indicated that microRNA 145 (miR-145) and its predicated target, erythropoietin-producing hepatoma (EPH) receptor A4 (EPHA4), was closely associated with ischemic stroke. In this study, we aimed to further explore their function in a model of oxygen-glucose deprivation (OGD). The expression of miR-145 in the blood of 44 patients with ischemic stroke and 37 normal controls was detected by qRT-PCR. After transfection with either the wild- or mutant-type pGL3-promoter EPHA4 3'UTR into the miR-145 mimic and miR-145 inhibitor, a dual-luciferase reporter assay was performed to explore the interaction between miR-145 and EPHA4. qRT-PCR and Western blot were performed to further explore the effects of miR-145 on EPHA4 expression after an miR-145 mimic, an miR-145 inhibitor or LV-sh-EPHA4 was transfected into cerebral cortical neurons. The expression of miR-145 was significantly upregulated in the blood of patients with ischemic stroke compared to that of normal controls. Dual-luciferase reporter assay, qRT-PCR and Western blot results indicated that miR-145 indeed targets EPHA4 through its 3'-UTR and regulates the expression level of EPHA4 at both the mRNA and protein levels. Moreover, the OGD model was successfully constructed, and miR-145 exerted a protective effects in cell viability in the OGD model by downregulating EPHA4. The expression of LOC105376244 could be regulated by the miR-145-EPHA4 interaction. MiR-145 exerted a protective effects in cell viability in the OGD model by downregulating EPHA4, which suggested their potential roles in ischemic stroke and requires further research.


Assuntos
Isquemia Encefálica/metabolismo , Córtex Cerebral/citologia , MicroRNAs/genética , Neurônios/citologia , Receptor EphA4/metabolismo , Idoso , Apoptose/efeitos dos fármacos , Isquemia Encefálica/patologia , Hipóxia Celular/fisiologia , Sobrevivência Celular/genética , Córtex Cerebral/metabolismo , Regulação para Baixo , Feminino , Glucose/metabolismo , Humanos , Masculino , MicroRNAs/sangue , Pessoa de Meia-Idade , Neurônios/metabolismo , Oxigênio/metabolismo , Cultura Primária de Células , RNA Mensageiro/metabolismo , Acidente Vascular Cerebral/metabolismo
2.
Nat Neurosci ; 22(7): 1061-1065, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31209378

RESUMO

A key assumption of optogenetics is that light only affects opsin-expressing neurons. However, illumination invariably heats tissue, and many physiological processes are temperature-sensitive. Commonly used illumination protocols increased the temperature by 0.2-2 °C and suppressed spiking in multiple brain regions. In the striatum, light delivery activated an inwardly rectifying potassium conductance and biased rotational behavior. Thus, careful consideration of light-delivery parameters is required, as even modest intracranial heating can confound interpretation of optogenetic experiments.


Assuntos
Córtex Cerebral/fisiologia , Corpo Estriado/fisiologia , Hipocampo/fisiologia , Neurônios/fisiologia , Temperatura Ambiente , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/efeitos da radiação , Animais , Compostos de Bário/farmacologia , Córtex Cerebral/citologia , Cloretos/farmacologia , Corpo Estriado/citologia , Hipocampo/citologia , Temperatura Alta , Transporte de Íons/efeitos dos fármacos , Transporte de Íons/efeitos da radiação , Luz , Camundongos , Atividade Motora/efeitos da radiação , Neurônios/efeitos dos fármacos , Neurônios/efeitos da radiação , Optogenética/métodos , Técnicas de Patch-Clamp , Potássio/metabolismo , Canais de Potássio Corretores do Fluxo de Internalização/efeitos dos fármacos , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Canais de Potássio Corretores do Fluxo de Internalização/efeitos da radiação , Projetos de Pesquisa
3.
Nat Commun ; 10(1): 2091, 2019 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-31064994

RESUMO

Caspase-1 activated in inflammasomes triggers a programmed necrosis called pyroptosis, which is mediated by gasdermin D (GSDMD). However, GSDMD-deficient cells are still susceptible to caspase-1-mediated cell death. Therefore, here, we investigate the mechanism of caspase-1-initiated cell death in GSDMD-deficient cells. Inflammasome stimuli induce apoptosis accompanied by caspase-3 activation in GSDMD-deficient macrophages, which largely relies on caspase-1. Chemical dimerization of caspase-1 induces pyroptosis in GSDMD-sufficient cells, but apoptosis in GSDMD-deficient cells. Caspase-1-induced apoptosis involves the Bid-caspase-9-caspase-3 axis, which can be followed by GSDME-dependent secondary necrosis/pyroptosis. However, Bid ablation does not completely abolish the cell death, suggesting the existence of an additional mechanism. Furthermore, cortical neurons and mast cells exhibit little or low GSDMD expression and undergo apoptosis after oxygen glucose deprivation and nigericin stimulation, respectively, in a caspase-1- and Bid-dependent manner. This study clarifies the molecular mechanism and biological roles of caspase-1-induced apoptosis in GSDMD-low/null cell types.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Caspase 1/fisiologia , Inflamassomos/imunologia , Piroptose/imunologia , Receptores Estrogênicos/metabolismo , Animais , Proteínas Reguladoras de Apoptose/genética , Proteína Agonista de Morte Celular de Domínio Interatuante com BH3/genética , Proteína Agonista de Morte Celular de Domínio Interatuante com BH3/metabolismo , Caspase 3/metabolismo , Caspase 9/metabolismo , Linhagem Celular Tumoral , Córtex Cerebral/citologia , Embrião de Mamíferos , Técnicas de Inativação de Genes , Macrófagos/citologia , Macrófagos/imunologia , Macrófagos/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Nigericina/farmacologia , Cultura Primária de Células , Piroptose/efeitos dos fármacos , Células RAW 264.7 , Salmonella typhimurium/imunologia
4.
Nat Commun ; 10(1): 2129, 2019 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-31086189

RESUMO

De novo heterozygous missense variants in the γ-tubulin gene TUBG1 have been linked to human malformations of cortical development associated with intellectual disability and epilepsy. Here, we investigated through in-utero electroporation and in-vivo studies, how four of these variants affect cortical development. We show that TUBG1 mutants affect neuronal positioning, disrupting the locomotion of new-born neurons but without affecting progenitors' proliferation. We further demonstrate that pathogenic TUBG1 variants are linked to reduced microtubule dynamics but without major structural nor functional centrosome defects in subject-derived fibroblasts. Additionally, we developed a knock-in Tubg1Y92C/+ mouse model and assessed consequences of the mutation. Although centrosomal positioning in bipolar neurons is correct, they fail to initiate locomotion. Furthermore, Tubg1Y92C/+ animals show neuroanatomical and behavioral defects and increased epileptic cortical activity. We show that Tubg1Y92C/+ mice partially mimic the human phenotype and therefore represent a relevant model for further investigations of the physiopathology of cortical malformations.


Assuntos
Malformações do Desenvolvimento Cortical/genética , Microtúbulos/metabolismo , Neurogênese/genética , Neurônios/fisiologia , Tubulina (Proteína)/genética , Animais , Comportamento Animal , Movimento Celular/genética , Centrossomo/metabolismo , Córtex Cerebral/anormalidades , Córtex Cerebral/citologia , Córtex Cerebral/diagnóstico por imagem , Modelos Animais de Doenças , Embrião de Mamíferos , Epilepsia/genética , Feminino , Fibroblastos/citologia , Fibroblastos/metabolismo , Fibroblastos/ultraestrutura , Técnicas de Introdução de Genes , Predisposição Genética para Doença , Células HeLa , Humanos , Microscopia Intravital , Masculino , Camundongos , Camundongos Transgênicos , Microscopia Confocal , Microscopia Eletrônica , Microtúbulos/genética , Mutação de Sentido Incorreto
5.
Nat Commun ; 10(1): 1817, 2019 04 18.
Artigo em Inglês | MEDLINE | ID: mdl-31000720

RESUMO

Neurodegenerative diseases like Alzheimer's disease, Parkinson's disease and Huntington's disease manifest with the neuronal accumulation of toxic proteins. Since autophagy upregulation enhances the clearance of such proteins and ameliorates their toxicities in animal models, we and others have sought to re-position/re-profile existing compounds used in humans to identify those that may induce autophagy in the brain. A key challenge with this approach is to assess if any hits identified can induce neuronal autophagy at concentrations that would be seen in humans taking the drug for its conventional indication. Here we report that felodipine, an L-type calcium channel blocker and anti-hypertensive drug, induces autophagy and clears diverse aggregate-prone, neurodegenerative disease-associated proteins. Felodipine can clear mutant α-synuclein in mouse brains at plasma concentrations similar to those that would be seen in humans taking the drug. This is associated with neuroprotection in mice, suggesting the promise of this compound for use in neurodegeneration.


Assuntos
Autofagia/efeitos dos fármacos , Reposicionamento de Medicamentos , Felodipino/farmacologia , Doenças Neurodegenerativas/tratamento farmacológico , Fármacos Neuroprotetores/farmacologia , Animais , Animais Geneticamente Modificados , Linhagem Celular , Córtex Cerebral/citologia , Córtex Cerebral/patologia , Modelos Animais de Doenças , Embrião de Mamíferos , Embrião não Mamífero , Felodipino/uso terapêutico , Feminino , Humanos , Células-Tronco Pluripotentes Induzidas , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mutação , Doenças Neurodegenerativas/genética , Doenças Neurodegenerativas/patologia , Neurônios/efeitos dos fármacos , Neurônios/patologia , Fármacos Neuroprotetores/uso terapêutico , Cultura Primária de Células , Suínos , Porco Miniatura , Resultado do Tratamento , Peixe-Zebra , alfa-Sinucleína/genética , alfa-Sinucleína/metabolismo
6.
PLoS Comput Biol ; 15(4): e1006902, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30939135

RESUMO

Experimental studies have begun revealing essential properties of the structural connectivity and the spatiotemporal activity dynamics of cortical circuits. To integrate these properties from anatomy and physiology, and to elucidate the links between them, we develop a novel cortical circuit model that captures a range of realistic features of synaptic connectivity. We show that the model accounts for the emergence of higher-order connectivity structures, including highly connected hub neurons that form an interconnected rich-club. The circuit model exhibits a rich repertoire of dynamical activity states, ranging from asynchronous to localized and global propagating wave states. We find that around the transition between asynchronous and localized propagating wave states, our model quantitatively reproduces a variety of major empirical findings regarding neural spatiotemporal dynamics, which otherwise remain disjointed in existing studies. These dynamics include diverse coupling (correlation) between spiking activity of individual neurons and the population, dynamical wave patterns with variable speeds and precise temporal structures of neural spikes. We further illustrate how these neural dynamics are related to the connectivity properties by analysing structural contributions to variable spiking dynamics and by showing that the rich-club structure is related to the diverse population coupling. These findings establish an integrated account of structural connectivity and activity dynamics of local cortical circuits, and provide new insights into understanding their working mechanisms.


Assuntos
Córtex Cerebral/fisiologia , Modelos Neurológicos , Rede Nervosa/fisiologia , Potenciais de Ação , Animais , Córtex Cerebral/citologia , Biologia Computacional , Simulação por Computador , Humanos , Vias Neurais/fisiologia , Neurônios/fisiologia , Análise Espaço-Temporal
7.
Nat Commun ; 10(1): 1662, 2019 04 10.
Artigo em Inglês | MEDLINE | ID: mdl-30971684

RESUMO

Large-scale microscopy approaches are transforming brain imaging, but currently lack efficient multicolor contrast modalities. We introduce chromatic multiphoton serial (ChroMS) microscopy, a method integrating one-shot multicolor multiphoton excitation through wavelength mixing and serial block-face image acquisition. This approach provides organ-scale micrometric imaging of spectrally distinct fluorescent proteins and label-free nonlinear signals with constant micrometer-scale resolution and sub-micron channel registration over the entire imaged volume. We demonstrate tridimensional (3D) multicolor imaging over several cubic millimeters as well as brain-wide serial 2D multichannel imaging. We illustrate the strengths of this method through color-based 3D analysis of astrocyte morphology and contacts in the mouse cerebral cortex, tracing of individual pyramidal neurons within densely Brainbow-labeled tissue, and multiplexed whole-brain mapping of axonal projections labeled with spectrally distinct tracers. ChroMS will be an asset for multiscale and system-level studies in neuroscience and beyond.


Assuntos
Córtex Cerebral/diagnóstico por imagem , Imagem Tridimensional/métodos , Proteínas Luminescentes/química , Microscopia de Fluorescência por Excitação Multifotônica/métodos , Neuroimagem/métodos , Animais , Astrócitos/metabolismo , Córtex Cerebral/citologia , Cor , Feminino , Vetores Genéticos/administração & dosagem , Vetores Genéticos/genética , Células HEK293 , Humanos , Proteínas Luminescentes/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Modelos Animais , Nestina/genética , Técnicas de Rastreamento Neuroanatômico/métodos , Parvovirinae/genética , Células Piramidais/metabolismo , Transfecção
8.
BMC Res Notes ; 12(1): 225, 2019 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-30987672

RESUMO

OBJECTIVE: Delivery of constructs for silencing or over-expressing genes or their modified versions is a crucial step for studying neuronal cell biology. Therefore, efficient transfection is important for the success of these experimental techniques especially in post-mitotic cells like neurons. In this study, we have assessed the transfection rate, using a previously established protocol, in both primary cortical cultures and neuroblastoma cell lines. Transfection efficiencies in these preparations have not been systematically determined before. RESULTS: Transfection efficiencies obtained herein were (10-12%) for neuroblastoma, (5-12%) for primary astrocytes and (1.3-6%) for primary neurons. We also report on cell-type specific transfection efficiency of neurons and astrocytes within primary cortical cultures when applying cell-type selective transfection protocols. Previous estimations described in primary cortical or hippocampal cultures were either based on general observations or on data derived from unspecified number of biological and/or technical replicates. Also to the best of our knowledge, transfection efficiency of pure primary neuronal cultures or astrocytes cultured in the context of pure or mixed (neurons/astrocytes) population cultures have not been previously determined. The transfection strategy used herein represents a convenient, and a straightforward tool for targeted cell transfection that can be utilized in a variety of in vitro applications.


Assuntos
Astrócitos/metabolismo , Células-Tronco Neurais/metabolismo , Neurônios/metabolismo , Plasmídeos/metabolismo , Transfecção/métodos , Animais , Antígenos Nucleares/genética , Antígenos Nucleares/metabolismo , Astrócitos/citologia , Astrócitos/efeitos dos fármacos , Biomarcadores/metabolismo , Diferenciação Celular , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Córtex Cerebral/citologia , Córtex Cerebral/metabolismo , Técnicas de Cocultura , Expressão Gênica , Genes Reporter , Proteína Glial Fibrilar Ácida/genética , Proteína Glial Fibrilar Ácida/metabolismo , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Humanos , Lipídeos/química , Lipídeos/farmacologia , Camundongos , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/metabolismo , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Células-Tronco Neurais/citologia , Células-Tronco Neurais/efeitos dos fármacos , Neurônios/citologia , Neurônios/efeitos dos fármacos , Especificidade de Órgãos , Plasmídeos/química , Cultura Primária de Células
9.
J Neuroinflammation ; 16(1): 71, 2019 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-30947729

RESUMO

BACKGROUND: HIV-associated neurocognitive disorders (HANDs) afflict more than half of HIV-1-positive individuals. The transactivator of transcription (Tat) produced by HIV virus elicits inflammatory process and is a major neurotoxic mediator that induce neuron damage during HAND pathogenesis. Activated astrocytes are important cells involved in neuroinflammation and neuronal damage. Purinergic receptors expressed in astrocytes participate in a positive feedback loop in virus-induced neurotoxicity. Here, we investigated that whether P2Y4R, a P2Y receptor subtype, that expressed in astrocyte participates in Tat-induced neuronal death in vitro and in vivo. METHODS: Soluble Tat protein was performed to determine the expression of P2Y4R and proinflammatory cytokines in astrocytes using siRNA technique via real-time PCR, Western blot, and immunofluorescence assays. Cytometric bead array was used to measure proinflammatory cytokine release. The TUNEL staining and MTT cell viability assay were analyzed for HT22 cell apoptosis and viability, and the ApopTag® peroxidase in situ apoptosis detection kit and cresyl violet staining for apoptosis and death of hippocampal neuron in vivo. RESULTS: We found that Tat challenge increased the expression of P2Y4R in astrocytes. P2Y4R signaling in astrocytes was involved in Tat-induced inflammatory cytokine production via PI3K/Akt- and ERK1/2-dependent pathways. Knockdown of P2Y4R expression significantly reduced inflammatory cytokine production and relieved Tat-mediated neuronal apoptosis in vitro. Furthermore, in vivo challenged with Tat, P2Y4R knockdown mice showed decreased inflammation and neuronal damage, especially in hippocampal CA1 region. CONCLUSIONS: Our data provide novel insights into astrocyte-mediated neuron damage during HIV-1 infection and suggest a potential therapeutic target for HANDs.


Assuntos
Astrócitos/efeitos dos fármacos , Citocinas/metabolismo , Neurônios/efeitos dos fármacos , Receptores Purinérgicos P2/metabolismo , Transdução de Sinais/fisiologia , Produtos do Gene tat do Vírus da Imunodeficiência Humana/farmacologia , Trifosfato de Adenosina/metabolismo , Animais , Animais Recém-Nascidos , Células Cultivadas , Córtex Cerebral/citologia , Inibidores Enzimáticos/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Proteína Glial Fibrilar Ácida/genética , Proteína Glial Fibrilar Ácida/metabolismo , Glioma/patologia , Humanos , Sistema de Sinalização das MAP Quinases , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/patologia , Proteína Oncogênica v-akt , Fosfatidilinositol 3-Quinases , RNA Mensageiro/metabolismo , Receptores Purinérgicos P2/genética , Transdução de Sinais/genética , Transdução Genética , Produtos do Gene tat do Vírus da Imunodeficiência Humana/genética , Produtos do Gene tat do Vírus da Imunodeficiência Humana/metabolismo
10.
PLoS Comput Biol ; 15(3): e1006755, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30883546

RESUMO

We use stochastic neural field theory to analyze the stimulus-dependent tuning of neural variability in ring attractor networks. We apply perturbation methods to show how the neural field equations can be reduced to a pair of stochastic nonlinear phase equations describing the stochastic wandering of spontaneously formed tuning curves or bump solutions. These equations are analyzed using a modified version of the bivariate von Mises distribution, which is well-known in the theory of circular statistics. We first consider a single ring network and derive a simple mathematical expression that accounts for the experimentally observed bimodal (or M-shaped) tuning of neural variability. We then explore the effects of inter-network coupling on stimulus-dependent variability in a pair of ring networks. These could represent populations of cells in two different layers of a cortical hypercolumn linked via vertical synaptic connections, or two different cortical hypercolumns linked by horizontal patchy connections within the same layer. We find that neural variability can be suppressed or facilitated, depending on whether the inter-network coupling is excitatory or inhibitory, and on the relative strengths and biases of the external stimuli to the two networks. These results are consistent with the general observation that increasing the mean firing rate via external stimuli or modulating drives tends to reduce neural variability.


Assuntos
Córtex Cerebral/citologia , Modelos Neurológicos , Neurônios/fisiologia , Processos Estocásticos , Animais
11.
Nat Neurosci ; 22(4): 669-679, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30886407

RESUMO

Neural organoids have the potential to improve our understanding of human brain development and neurological disorders. However, it remains to be seen whether these tissues can model circuit formation with functional neuronal output. Here we have adapted air-liquid interface culture to cerebral organoids, leading to improved neuronal survival and axon outgrowth. The resulting thick axon tracts display various morphologies, including long-range projection within and away from the organoid, growth-cone turning, and decussation. Single-cell RNA sequencing reveals various cortical neuronal identities, and retrograde tracing demonstrates tract morphologies that match proper molecular identities. These cultures exhibit active neuronal networks, and subcortical projecting tracts can innervate mouse spinal cord explants and evoke contractions of adjacent muscle in a manner dependent on intact organoid-derived innervating tracts. Overall, these results reveal a remarkable self-organization of corticofugal and callosal tracts with a functional output, providing new opportunities to examine relevant aspects of human CNS development and disease.


Assuntos
Córtex Cerebral/crescimento & desenvolvimento , Neurônios/fisiologia , Organoides/crescimento & desenvolvimento , Técnicas de Cultura de Tecidos/métodos , Axônios/fisiologia , Sobrevivência Celular , Córtex Cerebral/citologia , Feminino , Humanos , Masculino , Vias Neurais/citologia , Vias Neurais/fisiologia , Neurônios/citologia , Organoides/citologia , Células-Tronco Pluripotentes/fisiologia
12.
Nat Neurosci ; 22(4): 618-626, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30858601

RESUMO

Hippocampus, granular retrosplenial cortex (RSCg), and anterior thalamic nuclei (ATN) interact to mediate diverse cognitive functions. To identify cellular mechanisms underlying hippocampo-thalamo-retrosplenial interactions, we investigated the potential circuit suggested by projections to RSCg layer 1 (L1) from GABAergic CA1 neurons and ATN. We find that CA1→RSCg projections stem from GABAergic neurons with a distinct morphology, electrophysiology, and molecular profile. Their long-range axons inhibit L5 pyramidal neurons in RSCg via potent synapses onto apical tuft dendrites in L1. These inhibitory inputs intercept L1-targeting thalamocortical excitatory inputs from ATN to coregulate RSCg activity. Subicular axons, in contrast, excite proximal dendrites in deeper layers. Short-term plasticity differs at each connection. Chemogenetically abrogating CA1→RSCg or ATN→RSCg connections oppositely affects the encoding of contextual fear memory. Our findings establish retrosplenial-projecting CA1 neurons as a distinct class of long-range dendrite-targeting GABAergic neuron and delineate an unusual cortical circuit specialized for integrating long-range inhibition and thalamocortical excitation.


Assuntos
Núcleos Anteriores do Tálamo/citologia , Núcleos Anteriores do Tálamo/fisiologia , Região CA1 Hipocampal/citologia , Região CA1 Hipocampal/fisiologia , Córtex Cerebral/citologia , Córtex Cerebral/fisiologia , Neurônios GABAérgicos/citologia , Neurônios GABAérgicos/fisiologia , Animais , Condicionamento Clássico/fisiologia , Medo/fisiologia , Feminino , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Inibição Neural , Vias Neurais/citologia , Vias Neurais/fisiologia , Neurônios/citologia , Neurônios/fisiologia , Potenciais Sinápticos
13.
eNeuro ; 6(1)2019 Jan-Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30899776

RESUMO

Vestibulospinal neurons are organized into discrete groups projecting from brainstem to spinal cord, enabling vertebrates to maintain proper balance and posture. The two largest groups are the lateral vestibulospinal tract (LVST) group and the contralateral medial vestibulospinal tract (cMVST) group, with different projection lateralities and functional roles. In search of a molecular basis for these differences, we performed RNA sequencing on LVST and cMVST neurons from mouse and chicken embryos followed by immunohistofluorescence validation. Focusing on transcription factor (TF)-encoding genes, we identified TF signatures that uniquely distinguish the LVST from the cMVST group and further parse different rhombomere-derived portions comprising the cMVST group. Immunohistofluorescence assessment of the CNS from spinal cord to cortex demonstrated that these TF signatures are restricted to the respective vestibulospinal groups and some neurons in their immediate vicinity. Collectively, these results link the combinatorial expression of TFs to developmental and functional subdivisions within the vestibulospinal system.


Assuntos
Córtex Cerebral/citologia , Neurônios/citologia , Medula Espinal/citologia , Fatores de Transcrição/metabolismo , Núcleos Vestibulares/citologia , Animais , Evolução Biológica , Córtex Cerebral/metabolismo , Embrião de Galinha , Camundongos Transgênicos , Vias Neurais/citologia , Vias Neurais/metabolismo , Neurônios/metabolismo , Medula Espinal/metabolismo , Transcriptoma , Núcleos Vestibulares/metabolismo
14.
Artigo em Inglês | MEDLINE | ID: mdl-30814934

RESUMO

Adaptation is a mechanism by which cortical neurons adjust their responses according to recently viewed stimuli. Visual information is processed in a circuit formed by feedforward (FF) and feedback (FB) synaptic connections of neurons in different cortical layers. Here, the functional role of FF-FB streams and their synaptic dynamics in adaptation to natural stimuli is assessed in psychophysics and neural model. We propose a cortical model which predicts psychophysically observed motion adaptation aftereffects (MAE) after exposure to geometrically distorted natural image sequences. The model comprises direction selective neurons in V1 and MT connected by recurrent FF and FB dynamic synapses. Psychophysically plausible model MAEs were obtained from synaptic changes within neurons tuned to salient direction signals of the broadband natural input. It is conceived that, motion disambiguation by FF-FB interactions is critical to encode this salient information. Moreover, only FF-FB dynamic synapses operating at distinct rates predicted psychophysical MAEs at different adaptation time-scales which could not be accounted for by single rate dynamic synapses in either of the streams. Recurrent FF-FB pathways thereby play a role during adaptation in a natural environment, specifically in inducing multilevel cortical plasticity to salient information and in mediating adaptation at different time-scales.


Assuntos
Adaptação Fisiológica/fisiologia , Córtex Cerebral/citologia , Modelos Neurológicos , Rede Nervosa/fisiologia , Neurônios/fisiologia , Animais , Humanos , Psicofísica , Sinapses/fisiologia
15.
Emerg Microbes Infect ; 8(1): 307-326, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30866785

RESUMO

The harmful effects of ZIKA virus (ZIKV) infection are reflected by severe neurological manifestations such as microcephaly in neonates and other complications associated with Guillain-Barré syndrome in adults. The transmission dynamics of ZIKV in or between neurons, or within the developing brains of the foetuses are not fully understood. Using primary cultures of murine cortical neurons, we show that ZIKV uses exosomes as mediators of viral transmission between neurons. Cryo-electron microscopy showed heterogeneous population of neuronal exosomes with a size range of 30-200 nm. Increased production of exosomes from neuronal cells was noted upon ZIKV infection. Neuronal exosomes contained both ZIKV viral RNA and protein(s) that were highly infectious to naïve cells. RNaseA and neutralizing antibodies treatment studies suggest the presence of viral RNA/proteins inside exosomes. Exosomes derived from time- and dose-dependent incubations showed increasing viral loads suggesting higher packaging and delivery of ZIKV RNA and proteins. Furthermore, we noted that ZIKV induced both activity and gene expression of neutral Sphingomyelinase (nSMase)-2/SMPD3, an important molecule that regulates production and release of exosomes. Silencing of SMPD3 in neurons resulted in reduced viral burden and transmission through exosomes. Treatment with SMPD3 specific inhibitor GW4869, significantly reduced ZIKV loads in both cortical neurons and in exosomes derived from these neuronal cells. Taken together, our results suggest that ZIKV modulates SMPD3 activity in cortical neurons for its infection and transmission through exosomes perhaps leading to severe neuronal death that may result in neurological manifestations such as microcephaly in the developing embryonic brains.


Assuntos
Córtex Cerebral/virologia , Exossomos/virologia , Esfingomielina Fosfodiesterase/genética , Esfingomielina Fosfodiesterase/metabolismo , Zika virus/fisiologia , Compostos de Anilina/farmacologia , Animais , Compostos de Benzilideno/farmacologia , Células Cultivadas , Córtex Cerebral/citologia , Microscopia Crioeletrônica , Exossomos/genética , Exossomos/metabolismo , Regulação Enzimológica da Expressão Gênica , Camundongos , Neurônios/citologia , Neurônios/virologia , Fatores de Tempo , Carga Viral/efeitos dos fármacos , Montagem de Vírus/efeitos dos fármacos
16.
J Mol Neurosci ; 68(1): 29-37, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30806968

RESUMO

Acyl ghrelin, a novel brain-gut peptide, is an endogenous ligand for the growth hormone secretagogue receptor. Accumulated research data have shown that acyl ghrelin exercises a significant neuroprotective effect against cerebral ischemia/reperfusion (I/R) injury in animal models and in cultured neurons during the acute phase, usually, 1 day after cerebral ischemia. The chronic effects of acyl ghrelin 1 week after brain ischemia remain largely unknown. In this study, we explored the effects of acyl ghrelin on cultured organotypic brain slices and cortical neurons which were injured by oxygen-glucose deprivation/reperfusion(OGD/R) for 7 days. The underlying molecular mechanisms were deciphered based on label-free proteomic analysis. Acyl ghrelin treatment promoted neurite (axons and dendrites) growth and alleviated the neuronal damage in both cultured brain slices and neurons. Proteomic analysis showed that cell division control protein 42 (Cdc42) mediates the effects of acyl ghrelin on neurite growth. Acyl ghrelin stimulated the expression of Cdc42 and neurite growth in cultured neurons comparing with OGD/R group. Inhibition of Cdc42 attenuated the effects of acyl ghrelin. These results suggest that acyl ghrelin promotes neurite growth during the later stage after OGD/R injury via Cdc42. Our study suggests that acyl ghrelin may be promising to restore the neuronal structure in the late phase after stroke.


Assuntos
Isquemia Encefálica/metabolismo , Grelina/metabolismo , Crescimento Neuronal , Animais , Hipóxia Celular , Células Cultivadas , Córtex Cerebral/citologia , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Grelina/farmacologia , Glucose/deficiência , Camundongos , Camundongos Endogâmicos C57BL , Oxigênio/metabolismo , Proteoma/genética , Proteoma/metabolismo , Proteína cdc42 de Ligação ao GTP/metabolismo
17.
J Neuroinflammation ; 16(1): 41, 2019 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-30777083

RESUMO

BACKGROUND: Excessive iron contributes to oxidative stress after central nervous system injury. NADPH oxidase (NOX) enzymes are upregulated in microglia after pro-inflammatory activation and contribute to oxidative stress. The relationship between iron, microglia, NOX, and oxidative stress is currently unclear. METHODS: We evaluated the effects of iron on lipopolysaccharide (LPS)-activated microglia and its secondary effect within neuronal co-cultures. Further, NOX2 and four specific inhibitors were tested to evaluate the relationship with the reactive oxygen species (ROS)-producing enzymes. RESULTS: An iron dose-dependent increase in ROS production among microglia treated with LPS was identified. Interestingly, despite this increase in ROS, inflammatory polarization alterations were not detected among the microglia after exposure to iron and LPS. Co-culture experimentation between primary neurons and exposed microglia (iron and LPS) significantly reduced neuronal cell number at 24 h, suggesting a profound neurotoxic effect despite the lack of a change in polarization phenotype. NOX2 and NOX4 inhibition significantly reduced ROS production among microglia exposed to iron and LPS and reduced neuronal damage and death in response to microglial co-culture. CONCLUSIONS: In conclusion, iron significantly increased ROS production and neurotoxicity without exacerbating LP-activated microglia phenotype in vitro, suggesting that iron contributes to microglia-related oxidative stress, and this may be a viable therapeutic target for injury or neurodegeneration. Further, this study highlights both NOX2 and NOX4 as potential therapeutic targets in the treatment of iron-induced microglia-related inflammation and neurotoxicity.


Assuntos
Ferro/farmacologia , Microglia/efeitos dos fármacos , NADPH Oxidases/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Aminopiridinas/farmacologia , Animais , Animais Recém-Nascidos , Caspase 3/metabolismo , Morte Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Córtex Cerebral/citologia , Técnicas de Cocultura , Inibidores Enzimáticos/farmacologia , Ferritinas/genética , Ferritinas/metabolismo , Ferro/metabolismo , Lipopolissacarídeos/farmacologia , Microglia/fisiologia , Neurônios/efeitos dos fármacos , Estresse Oxidativo/fisiologia , Pirazóis/farmacologia , Piridinas/farmacologia , Ratos , Ratos Sprague-Dawley , Sulfonamidas/farmacologia
18.
Glia ; 67(4): 718-728, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30793389

RESUMO

During development or after brain injury, oligodendrocyte precursor cells (OPCs) differentiate into oligodendrocytes to supplement the number of oligodendrocytes. Although mechanisms of OPC differentiation have been extensively examined, the role of epigenetic regulators, such as histone deacetylases (HDACs) and DNA methyltransferase enzymes (DNMTs), in this process is still mostly unknown. Here, we report the differential roles of epigenetic regulators in OPC differentiation. We prepared primary OPC cultures from neonatal rat cortex. Our cultured OPCs expressed substantial amounts of mRNA for HDAC1, HDAC2, DNMT1, and DNMT3a. mRNA levels of HDAC1 and HDAC2 were both decreased by the time OPCs differentiated into myelin-basic-protein expressing oligodendrocytes. However, DNMT1 or DNMT3a mRNA level gradually decreased or increased during the differentiation step, respectively. We then knocked down those regulators in cultured OPCs with siRNA technique before starting OPC differentiation. While HDAC1 knockdown suppressed OPC differentiation, HDAC2 knockdown promoted OPC differentiation. DNMT1 knockdown also suppressed OPC differentiation, but unlike HDAC1/2, DNMT1-deficient cells showed cell damage during the later phase of OPC differentiation. On the other hand, when OPCs were transfected with siRNA for DNMT3a, the number of OPCs was decreased, indicating that DNMT3a may participate in OPC survival/proliferation. Taken together, these data demonstrate that each epigenetic regulator has different phase-specific roles in OPC survival and differentiation.


Assuntos
Epigênese Genética/fisiologia , Células Precursoras de Oligodendrócitos/fisiologia , Animais , Animais Recém-Nascidos , Diferenciação Celular , Córtex Cerebral/citologia , DNA (Citosina-5-)-Metiltransferases/genética , DNA (Citosina-5-)-Metiltransferases/metabolismo , Metilação de DNA/efeitos dos fármacos , Metilação de DNA/genética , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Histona Desacetilases/genética , Histona Desacetilases/metabolismo , Proteína Básica da Mielina/genética , Proteína Básica da Mielina/metabolismo , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Ratos , Ratos Sprague-Dawley , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/genética , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/metabolismo , Transfecção
19.
Brain Struct Funct ; 224(3): 985-1008, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30739157

RESUMO

The classical theory of cortical systematic variation has been independently described in reptiles, monotremes, marsupials and placental mammals, including primates, suggesting a common bauplan in the evolution of the cortex. The Structural Model is based on the systematic variation of the cortex and is a platform for advancing testable hypotheses about cortical organization and function across species, including humans. The Structural Model captures the overall laminar structure of areas by dividing the cortical architectonic continuum into discrete categories (cortical types), which can be used to test hypotheses about cortical organization. By type, the phylogenetically ancient limbic cortices-which form a ring at the base of the cerebral hemisphere-are agranular if they lack layer IV, or dysgranular if they have an incipient granular layer IV. Beyond the dysgranular areas, eulaminate type cortices have six layers. The number and laminar elaboration of eulaminate areas differ depending on species or cortical system within a species. The construct of cortical type retains the topology of the systematic variation of the cortex and forms the basis for a predictive Structural Model, which has successfully linked cortical variation to the laminar pattern and strength of cortical connections, the continuum of plasticity and stability of areas, the regularities in the distribution of classical and novel markers, and the preferential vulnerability of limbic areas to neurodegenerative and psychiatric diseases. The origin of cortical types has been recently traced to cortical development, and helps explain the variability of diseases with an onset in ontogeny.


Assuntos
Evolução Biológica , Córtex Cerebral , Modelos Neurológicos , Vias Neurais/fisiologia , Plasticidade Neuronal/fisiologia , Animais , Córtex Cerebral/citologia , Córtex Cerebral/patologia , Córtex Cerebral/fisiologia , Humanos
20.
J Neuroinflammation ; 16(1): 35, 2019 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-30760285

RESUMO

BACKGROUND: Extracellular accumulation of amyloid ß-peptide (Aß) is one of pathological hallmarks of Alzheimer's disease (AD) and contributes to the neuronal loss. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum (ER) stress-inducible neurotrophic factor. Many groups, including ours, have proved that MANF rescues neuronal loss in several neurological disorders, such as Parkinson's disease and cerebral ischemia. However, whether MANF exerts its protective effect against Aß neurotoxicity in AD remains unknown. METHODS: In the present study, the characteristic expressions of MANF in Aß1-42-treated neuronal cells as well as in the brains of APP/PS1 transgenic mice were analyzed by immunofluorescence staining, qPCR, and Western blot. The effects of MANF overexpression, MANF knockdown, or recombination human MANF protein (rhMANF) on neuron viability, apoptosis, and the expression of ER stress-related proteins following Aß1-42 exposure were also investigated. RESULTS: The results showed the increased expressions of MANF, as well as ER stress markers immunoglobulin-binding protein (BiP) and C/EBP homologous protein (CHOP), in the brains of the APP/PS1 transgenic mice and Aß1-42-treated neuronal cells. MANF overexpression or rhMANF treatment partially protected against Aß1-42-induced neuronal cell death, associated with marked decrease of cleaved caspase-3, whereas MANF knockdown with siRNA aggravated Aß1-42 cytotoxicity including caspase-3 activation. Further study demonstrated that the expressions of BiP, ATF6, phosphorylated-IRE1, XBP1s, phosphorylated-eIF2α, ATF4, and CHOP were significantly downregulated by MANF overexpression or rhMANF treatment in neuronal cells following Aß1-42 exposure, whereas knockdown of MANF has the opposite effect. CONCLUSIONS: These findings demonstrate that MANF may exert neuroprotective effects against Aß-induced neurotoxicity through attenuating ER stress, suggesting that an applicability of MANF as a therapeutic candidate for AD.


Assuntos
Peptídeos beta-Amiloides/toxicidade , Apoptose/efeitos dos fármacos , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Fatores de Crescimento Neural/metabolismo , Fatores de Crescimento Neural/uso terapêutico , Neurônios/efeitos dos fármacos , Fragmentos de Peptídeos/toxicidade , Regulação para Cima/efeitos dos fármacos , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Células Cultivadas , Córtex Cerebral/citologia , Embrião de Mamíferos , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Fatores de Crescimento Neural/genética , Neuroblastoma/patologia , Fosfopiruvato Hidratase/metabolismo , Presenilina-1/genética , Presenilina-1/metabolismo , RNA Interferente Pequeno/farmacologia , RNA Interferente Pequeno/uso terapêutico
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA