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1.
Science ; 371(6530)2021 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-33574181

RESUMO

Circadian clocks temporally coordinate physiology and align it with geophysical time, which enables diverse life-forms to anticipate daily environmental cycles. In complex organisms, clock function originates from the molecular oscillator within each cell and builds upward anatomically into an organism-wide system. Recent advances have transformed our understanding of how clocks are connected to achieve coherence across tissues. Circadian misalignment, often imposed in modern society, disrupts coordination among clocks and has been linked to diseases ranging from metabolic syndrome to cancer. Thus, uncovering the physiological circuits whereby biological clocks achieve coherence will inform on both challenges and opportunities in human health.


Assuntos
Encéfalo/fisiologia , Relógios Circadianos/fisiologia , Ritmo Circadiano/fisiologia , Homeostase , Animais , Astrócitos/fisiologia , Comunicação Celular , Sinais (Psicologia) , Retroalimentação Fisiológica , Regulação da Expressão Gênica , Humanos , Neurônios do Núcleo Supraquiasmático/fisiologia
2.
Int J Mol Sci ; 21(24)2020 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-33348878

RESUMO

Astrocytes, the most abundant cell type in the brain, are non-excitable cells and play critical roles in brain function. Mature astrocytes typically exhibit a linear current-voltage relationship termed passive conductance, which is believed to enable astrocytes to maintain potassium homeostasis in the brain. We previously demonstrated that TWIK-1/TREK-1 heterodimeric channels mainly contribute to astrocytic passive conductance. However, the molecular identity of astrocytic passive conductance is still controversial and needs to be elucidated. Here, we report that spadin, an inhibitor of TREK-1, can dramatically reduce astrocytic passive conductance in brain slices. A series of gene silencing experiments demonstrated that spadin-sensitive currents are mediated by TWIK-1/TREK-1 heterodimeric channels in cultured astrocytes and hippocampal astrocytes from brain slices. Our study clearly showed that TWIK-1/TREK-1-heterodimeric channels can act as the main molecular machinery of astrocytic passive conductance, and suggested that spadin can be used as a specific inhibitor to control astrocytic passive conductance.


Assuntos
Astrócitos/fisiologia , Encéfalo/fisiologia , Regulação da Expressão Gênica/efeitos dos fármacos , Peptídeos/farmacologia , Canais de Potássio de Domínios Poros em Tandem/antagonistas & inibidores , Multimerização Proteica , Animais , Astrócitos/citologia , Astrócitos/efeitos dos fármacos , Encéfalo/citologia , Encéfalo/efeitos dos fármacos , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL
3.
Science ; 370(6512)2020 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-33004487

RESUMO

Injuries to the central nervous system (CNS) are inefficiently repaired. Resident neural stem cells manifest a limited contribution to cell replacement. We have uncovered a latent potential in neural stem cells to replace large numbers of lost oligodendrocytes in the injured mouse spinal cord. Integrating multimodal single-cell analysis, we found that neural stem cells are in a permissive chromatin state that enables the unfolding of a normally latent gene expression program for oligodendrogenesis after injury. Ectopic expression of the transcription factor OLIG2 unveiled abundant stem cell-derived oligodendrogenesis, which followed the natural progression of oligodendrocyte differentiation, contributed to axon remyelination, and stimulated functional recovery of axon conduction. Recruitment of resident stem cells may thus serve as an alternative to cell transplantation after CNS injury.


Assuntos
Células-Tronco Neurais/fisiologia , Neurogênese/fisiologia , Oligodendroglia/fisiologia , Regeneração da Medula Espinal/fisiologia , Animais , Astrócitos/fisiologia , Axônios/fisiologia , Linhagem da Célula , Epêndima/citologia , Epêndima/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Neurogênese/genética , Fator de Transcrição 2 de Oligodendrócitos/metabolismo , Oligodendroglia/citologia , Recuperação de Função Fisiológica/genética , Recuperação de Função Fisiológica/fisiologia , Remielinização/genética , Remielinização/fisiologia , Análise de Célula Única , Traumatismos da Medula Espinal/fisiopatologia , Regeneração da Medula Espinal/genética
5.
J Toxicol Sci ; 45(9): 559-567, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32879255

RESUMO

Lead is a main threat to human health due to its neurotoxicity and the astrocyte is known to be a common deposit site of lead in vivo. However, the detailed mechanisms related to lead exposure in the astrocytes were unclear. In order to deeply investigate this issue, we used Sprague-Dawley (SD) rats and astrocytes isolated from the hippocampus of SD rats to establish the lead-exposed animal and cell models through treating with lead acetate. The expression levels of GFAP, LC3, and p62 in the rat hippocampus were detected by immunofluorescence and Western blot after lead exposure. The effects of autophagy on lead-exposed astrocytes were studied by further autophagy inhibitor 3-methyladenine (3-MA) induction. Transmission electron microscopy was used to observe autophagosomes in astrocytes after lead acetate treatment, followed by assessing related autophagy protein markers. In addition, some inflammatory cytokines and oxidative stress markers were also evaluated after lead exposure and 3-MA administration. We found that lead exposure induced activation of astrocytes, as evidenced by increased GFAP levels and GFAP-positive staining cells in the rat hippocampus. Moreover, lead exposure induced autophagy in astrocytes, as evidenced by increased LC3II and Beclin 1 protein levels and decreased p62 expression in both the rat hippocampus and astrocytes, and it was confirmed that this autophagy was activated through blocking the downstream Akt/target of the rapamycin (mTOR) pathway in astrocytes. Furthermore, it was shown that treatment of lead acetate increased the release of tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß), and the accumulation of malondialdehyde (MDA) and myeloperoxidase (MPO) in astrocytes, which could be alleviated by further 3-MA induction. Therefore, we conclude that lead exposure can induce the autophagy of astrocytes via blocking the Akt/mTOR pathway, leading to accelerated release of inflammatory factors and oxidative stress indicators in astrocytes.


Assuntos
Astrócitos/metabolismo , Astrócitos/fisiologia , Autofagia/efeitos dos fármacos , Autofagia/genética , Compostos Organometálicos/toxicidade , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais/efeitos dos fármacos , Serina-Treonina Quinases TOR/metabolismo , Animais , Células Cultivadas , Proteína Glial Fibrilar Ácida/genética , Proteína Glial Fibrilar Ácida/metabolismo , Hipocampo/citologia , Interleucina-1beta/genética , Interleucina-1beta/metabolismo , Masculino , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/metabolismo , Estresse Oxidativo/genética , Ratos Sprague-Dawley , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/metabolismo
6.
J Pharmacol Sci ; 144(3): 147-150, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32800684

RESUMO

Astrocytes are the most abundant glial cells in the central nervous system (CNS), including the spinal cord. Neuronal damage induces astrocytes to become reactive and contribute to various CNS pathologies. Recent studies have demonstrated that astrocytes in the spinal dorsal horn (SDH) become reactive in a transcription factor signal transducer and activator of transcription 3-dependent manner without neuronal damage under chronic itch conditions, causing release of the factor lipocalin-2, leading to induction of sensitization of gastrin releasing peptide-induced chemical itch signaling in the SDH. In this review, we describe recent advances in our understanding of SDH neuronal pathways for itch transmission, the mechanisms of SDH astrocytic activation and its contribution to abnormal itch processing and discuss the role of reactive astrocytes in the SDH in abnormal sensory processing under chronic itch conditions.


Assuntos
Astrócitos/fisiologia , Prurido/etiologia , Corno Dorsal da Medula Espinal/citologia , Doença Crônica , Peptídeo Liberador de Gastrina/metabolismo , Humanos , Lipocalina-2/metabolismo , Vias Neurais , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais
7.
PLoS One ; 15(8): e0238104, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32822415

RESUMO

PURPOSE: To delineate responses of optic nerve head astrocytes to sustained intraocular pressure (IOP) elevation in mice. METHODS: We elevated IOP for 1 day to 6 weeks by intracameral microbead injection in 4 strains of mice. Astrocyte alterations were studied by transmission electron microscopy (TEM) including immunogold molecular localization, and by laser scanning microscopy (LSM) with immunofluorescence for integrin ß1, α-dystroglycan, and glial fibrillary acidic protein (GFAP). Astrocyte proliferation and apoptosis were quantified by Ki67 and TUNEL labeling, respectively. RESULTS: Astrocytes in normal optic nerve head expressed integrin ß1 and α-dystroglycan by LSM and TEM immunogold labeling at electron dense junctional complexes that were found only on cell membrane zones bordering their basement membranes (BM) at the peripapillary sclera (PPS) and optic nerve head capillaries. At 1-3 days after IOP elevation, abnormal extracellular spaces appeared between astrocytes near PPS, and axonal vesical and mitochondrial accumulation indicated axonal transport blockade. By 1 week, abnormal spaces increased, new collagen formation occurred, and astrocytes separated from their BM, leaving cell membrane fragments. Electron dense junctional complexes separated or were absent at the BM. Astrocyte proliferation was modest during the first week, while only occasional apoptotic astrocytes were observed by TEM and TUNEL. CONCLUSIONS: Astrocytes normally exhibit junctions with their BM which are disrupted by extended IOP elevation. Responses include reorientation of cell processes, new collagen formation, and cell proliferation.


Assuntos
Astrócitos/fisiologia , Glaucoma/patologia , Nervo Óptico/fisiologia , Animais , Apoptose , Astrócitos/citologia , Astrócitos/patologia , Proliferação de Células , Modelos Animais de Doenças , Proteína Glial Fibrilar Ácida/metabolismo , Pressão Intraocular , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Confocal , Microscopia Eletrônica de Transmissão , Nervo Óptico/citologia , Nervo Óptico/patologia
8.
J Pharmacol Sci ; 144(2): 76-82, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32736867

RESUMO

Astrocytes, comprising the primary glial-cell type, are involved in the formation and maturation of synapses, and thus contribute to sustainable synaptic transmission between neurons. Given that the animals in higher phylogenetic tree have brains with a higher density of glial cells with respect to neurons, there is a possibility that the relative astrocytic density directly influences synaptic transmission. However, the notion has not been tested thoroughly. Here we addressed it, by using a primary culture preparation where single hippocampal neurons are surrounded by a variable but a countable number of cortical astrocytes in dot-patterned microislands, and recording synaptic transmission by patch-clamp electrophysiology. Neurons with a higher astrocytic density showed a higher amplitude of the evoked excitatory postsynaptic current than that of neurons with a lower astrocytic density. The size of the readily releasable pool of synaptic vesicles per neuron was significantly larger. The frequency of spontaneous synaptic transmission was higher, but the amplitude was unchanged. The number of morphologically identified glutamatergic synapses was comparable, but the percentage of functional ones was increased, indicating a lower ratio of presynaptically silent synapses. Taken together, the higher astrocytic density enhanced excitatory synaptic transmission by increasing the fraction of functional synapses through presynaptic un-silencing.


Assuntos
Astrócitos/fisiologia , Encéfalo/citologia , Neurônios/fisiologia , Sinapses/fisiologia , Transmissão Sináptica , Animais , Astrócitos/patologia , Células Cultivadas , Potenciais Pós-Sinápticos Excitadores , Feminino , Camundongos Endogâmicos ICR , Neurônios/patologia , Filogenia , Gravidez
9.
PLoS One ; 15(7): e0234614, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32649728

RESUMO

Exosomes appear to be effective inter-cellular communicators delivering several types of molecules, such as proteins and RNAs, suggesting that they could influence neural stem cell (NSC) differentiation. Our RNA sequencing studies demonstrated that the RNAs related to cell proliferation and astrocyte differentiation were upregulated in human mesenchymal stem cells (hMSC) when co-cultured with exosomes obtained from the culture medium of human glioma cells (U87). Metallothionein 3 and elastin genes, which are related to cell proliferation, increased 10 and 7.2 fold, respectively. Expression of genes for astrocyte differentiation, such as tumor growth factor alpha, induced protein 3 of the NOTCH1 family, colony stimulating factor and interleukin 6 of the STAT3 family and Hes family bHLH transcription factor 1 also increased by 2.3, 10, 4.7 and 2.9 fold, respectively. We further examined the effects of these exosomes on rat fetal neural stem cell (rNSC) differentiation using the secreted exosomes from U87 glioma cells or exosomes from U87 cells that were stimulated with interleukin 1ß (IL-1ß). The rNSCs, extracted from rat brains at embryonic day 14 (E14), underwent a culture protocol that normally leads to predominant (~90%) differentiation to ODCs. However, in the presence of the exosomes from untreated or IL-1ß-treated U87 cells, significantly more cells differentiated into astrocytes, especially in the presence of exosomes obtained from the IL-1ß-challenged glioma cells. Moreover, glioma-derived exosomes appeared to inhibit rNSC differentiation into ODCs or astrocytes as indicated by a significantly increased population of unlabeled cells. A portion of the resulting astrocytes co-expressed both CD133 and glial fibrillary acidic protein (GFAP) suggesting that exosomes from U87 cells could promote astrocytic differentiation of NSCs with features expected from a transformed cell. Our data clearly demonstrated that exosomes secreted by human glioma cells provide a strong driving force for rat neural stem cells to differentiate into astrocytes, uncovering potential pathways and therapeutic targets that might control this aggressive tumor type.


Assuntos
Astrócitos/metabolismo , Diferenciação Celular/fisiologia , Exossomos/fisiologia , Células-Tronco Neurais/metabolismo , Animais , Astrócitos/fisiologia , Proliferação de Células , Células Cultivadas , Técnicas de Cocultura , Elastina/metabolismo , Exossomos/metabolismo , Regulação da Expressão Gênica/genética , Glioma/metabolismo , Humanos , Interleucina-6/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Células-Tronco Neurais/fisiologia , Neurônios/metabolismo , Cultura Primária de Células , Ratos , Fator de Transcrição STAT3/metabolismo
10.
Proc Natl Acad Sci U S A ; 117(31): 18810-18821, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32690710

RESUMO

In the central nervous system, glycogen-derived bioenergetic resources in astrocytes help promote tissue survival in response to focal neuronal stress. However, our understanding of the extent to which these resources are mobilized and utilized during neurodegeneration, especially in nearby regions that are not actively degenerating, remains incomplete. Here we modeled neurodegeneration in glaucoma, the world's leading cause of irreversible blindness, and measured how metabolites mobilize through astrocyte gap junctions composed of connexin 43 (Cx43). We elevated intraocular pressure in one eye and determined how astrocyte-derived metabolites in the contralateral optic projection responded. Remarkably, astrocyte networks expand and redistribute metabolites along distances even 10 mm in length, donating resources from the unstressed to the stressed projection in response to intraocular pressure elevation. While resource donation improves axon function and visual acuity in the directly stressed region, it renders the donating tissue susceptible to bioenergetic, structural, and physiological degradation. Intriguingly, when both projections are stressed in a WT animal, axon function and visual acuity equilibrate between the two projections even when each projection is stressed for a different length of time. This equilibration does not occur when Cx43 is not present. Thus, Cx43-mediated astrocyte metabolic networks serve as an endogenous mechanism used to mitigate bioenergetic stress and distribute the impact of neurodegenerative disease processes. Redistribution ultimately renders the donating optic nerve vulnerable to further metabolic stress, which could explain why local neurodegeneration does not remain confined, but eventually impacts healthy regions of the brain more broadly.


Assuntos
Astrócitos , Glaucoma/metabolismo , Doenças Neurodegenerativas/metabolismo , Animais , Astrócitos/metabolismo , Astrócitos/fisiologia , Conexina 43/genética , Conexina 43/metabolismo , Feminino , Junções Comunicantes/metabolismo , Pressão Intraocular/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos
11.
Neuron ; 107(3): 436-453.e12, 2020 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-32485136

RESUMO

New methods for investigating human astrocytes are urgently needed, given their critical role in the central nervous system. Here we show that CD49f is a novel marker for human astrocytes, expressed in fetal and adult brains from healthy and diseased individuals. CD49f can be used to purify fetal astrocytes and human induced pluripotent stem cell (hiPSC)-derived astrocytes. We provide single-cell and bulk transcriptome analyses of CD49f+ hiPSC-astrocytes and demonstrate that they perform key astrocytic functions in vitro, including trophic support of neurons, glutamate uptake, and phagocytosis. Notably, CD49f+ hiPSC-astrocytes respond to inflammatory stimuli, acquiring an A1-like reactive state, in which they display impaired phagocytosis and glutamate uptake and fail to support neuronal maturation. Most importantly, we show that conditioned medium from human reactive A1-like astrocytes is toxic to human and rodent neurons. CD49f+ hiPSC-astrocytes are thus a valuable resource for investigating human astrocyte function and dysfunction in health and disease.


Assuntos
Astrócitos/metabolismo , Células-Tronco Pluripotentes Induzidas/metabolismo , Integrina alfa6/metabolismo , Doença de Alzheimer/metabolismo , Animais , Astrócitos/fisiologia , Biomarcadores/metabolismo , Citometria de Fluxo , Perfilação da Expressão Gênica , Ácido Glutâmico/metabolismo , Humanos , Inflamação/metabolismo , Inflamação/fisiopatologia , Camundongos , Técnicas de Patch-Clamp , Fagocitose/fisiologia , RNA-Seq , Análise de Célula Única
12.
Ann N Y Acad Sci ; 1471(1): 72-85, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32449961

RESUMO

Astroglial complexity and pleomorphism have increased significantly with hominid evolution. This suggests a potential association between glial evolution and the development of human cognition, as well as between glial evolution and the advent of human-selective neurodegenerative and neuropsychiatric disorders.


Assuntos
Astrócitos/fisiologia , Encéfalo/fisiologia , Cognição/fisiologia , Neuroglia/fisiologia , Evolução Biológica , Humanos
13.
Nat Med ; 26(5): 769-780, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32284590

RESUMO

Our understanding of Alzheimer's disease (AD) pathophysiology remains incomplete. Here we used quantitative mass spectrometry and coexpression network analysis to conduct the largest proteomic study thus far on AD. A protein network module linked to sugar metabolism emerged as one of the modules most significantly associated with AD pathology and cognitive impairment. This module was enriched in AD genetic risk factors and in microglia and astrocyte protein markers associated with an anti-inflammatory state, suggesting that the biological functions it represents serve a protective role in AD. Proteins from this module were elevated in cerebrospinal fluid in early stages of the disease. In this study of >2,000 brains and nearly 400 cerebrospinal fluid samples by quantitative proteomics, we identify proteins and biological processes in AD brains that may serve as therapeutic targets and fluid biomarkers for the disease.


Assuntos
Doença de Alzheimer/metabolismo , Astrócitos/metabolismo , Encéfalo/metabolismo , Líquido Cefalorraquidiano/metabolismo , Metabolismo Energético , Microglia/metabolismo , Doença de Alzheimer/líquido cefalorraquidiano , Doença de Alzheimer/patologia , Animais , Astrócitos/patologia , Astrócitos/fisiologia , Biomarcadores/líquido cefalorraquidiano , Biomarcadores/metabolismo , Encéfalo/patologia , Estudos de Casos e Controles , Líquido Cefalorraquidiano/química , Estudos de Coortes , Progressão da Doença , Feminino , Redes Reguladoras de Genes/fisiologia , Humanos , Masculino , Espectrometria de Massas , Redes e Vias Metabólicas , Camundongos , Microglia/patologia , Microglia/fisiologia , Proteínas do Tecido Nervoso/análise , Proteínas do Tecido Nervoso/líquido cefalorraquidiano , Proteínas do Tecido Nervoso/metabolismo , Neurogênese/fisiologia , Proteômica/métodos , Tamanho da Amostra , Fatores de Tempo
14.
Neuron ; 106(6): 992-1008.e9, 2020 06 17.
Artigo em Inglês | MEDLINE | ID: mdl-32320644

RESUMO

Astrocytes play essential roles in brain function by supporting synaptic connectivity and associated circuits. How these roles are regulated by transcription factors is unknown. Moreover, there is emerging evidence that astrocytes exhibit regional heterogeneity, and the mechanisms controlling this diversity remain nascent. Here, we show that conditional deletion of the transcription factor nuclear factor I-A (NFIA) in astrocytes in the adult brain results in region-specific alterations in morphology and physiology that are mediated by selective DNA binding. Disruptions in astrocyte function following loss of NFIA are most pronounced in the hippocampus, manifested by impaired interactions with neurons, coupled with diminution of learning and memory behaviors. These changes in hippocampal astrocytes did not affect basal neuronal properties but specifically inhibited synaptic plasticity, which is regulated by NFIA in astrocytes through calcium-dependent mechanisms. Together, our studies reveal region-specific transcriptional dependencies for astrocytes and identify astrocytic NFIA as a key transcriptional regulator of hippocampal circuits.


Assuntos
Astrócitos/metabolismo , Encéfalo/metabolismo , Cálcio/metabolismo , Regulação da Expressão Gênica , Aprendizagem/fisiologia , Fatores de Transcrição NFI/genética , Animais , Astrócitos/fisiologia , Encéfalo/citologia , Encéfalo/fisiopatologia , Tronco Encefálico/citologia , Tronco Encefálico/metabolismo , Tronco Encefálico/fisiopatologia , Região CA1 Hipocampal/citologia , Região CA1 Hipocampal/metabolismo , Região CA1 Hipocampal/fisiopatologia , Hipocampo/citologia , Hipocampo/metabolismo , Hipocampo/fisiopatologia , Potenciação de Longa Duração/fisiologia , Memória/fisiologia , Camundongos , Camundongos Knockout , Vias Neurais , Plasticidade Neuronal , Neurônios , Bulbo Olfatório/citologia , Bulbo Olfatório/metabolismo , Bulbo Olfatório/fisiopatologia , Técnicas de Patch-Clamp , Córtex Pré-Frontal/citologia , Córtex Pré-Frontal/metabolismo , Córtex Pré-Frontal/fisiopatologia , Memória Espacial/fisiologia
15.
PLoS One ; 15(4): e0231752, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32330152

RESUMO

Astrocytes (AC) are the most abundant cells in the central nervous system. In the retina, astrocytes play important roles in the development and integrity of the retinal neurovasculature. Astrocytes dysfunction contributes to pathogenesis of a variety of neurovascular diseases including diabetic retinopathy. Recent studies have demonstrated the expression of Cyp1b1 in the neurovascular cells of the central nervous system including AC. We recently showed retinal AC constitutively express Cyp1b1, and global Cyp1b1-deficiency (Cyp1b1-/-) attenuates retinal ischemia-mediated neovascularization in vivo and the pro-angiogenic activity of retinal vascular cells in vitro. We also demonstrated that Cyp1b1 expression is a key regulator of retinal AC function. However, the underlying mechanisms involved need further investigation. Here we determined changes in the transcriptome profiles of Cyp1b1+/+ and Cyp1b1-/- retinal AC by RNA sequencing. We identified 585 differentially expressed genes, whose pathway enrichment analysis revealed the most significant pathways impacted in Cyp1b1-/- AC. These genes included those of axon guidance, extracellular matrix proteins and their receptors, cancer, cell adhesion molecules, TGF-ß signaling, and the focal adhesion modulation. The expression of a selected set of differentially expressed genes was confirmed by RT-qPCR analysis. To our knowledge, this is the first report of RNAseq investigation of the retinal AC transcriptome and the molecular pathways impacted by Cyp1b1 expression. These results demonstrated an important role for Cyp1b1 expression in the regulation of various retinal AC functions, which are important in neurovascular development and integrity.


Assuntos
Astrócitos/fisiologia , Adesão Celular/genética , Citocromo P-450 CYP1B1/metabolismo , Regulação da Expressão Gênica/fisiologia , Retina/fisiologia , Animais , Movimento Celular/genética , Células Cultivadas , Citocromo P-450 CYP1B1/genética , Feminino , Masculino , Camundongos , Camundongos Knockout , Cultura Primária de Células , RNA-Seq , Retina/citologia
16.
Proc Natl Acad Sci U S A ; 117(17): 9413-9422, 2020 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-32291340

RESUMO

Astrogenesis is repressed in the early embryonic period and occurs in the late embryonic period. A variety of external and internal signals contribute to the sequential differentiation of neural stem cells. Here, we discovered that immune-related CD93 plays a critical negative role in the regulation of astrogenesis in the mouse cerebral cortex. We show that CD93 expression is detected in neural stem cells and neurons but not in astrocytes and declines as differentiation proceeds. Cd93 knockout increases astrogenesis at the expense of neuron production during the late embryonic period. CD93 responds to the extracellular matrix protein Multimerin 2 (MMRN2) to trigger the repression of astrogenesis. Mechanistically, CD93 delivers signals to ß-Catenin through a series of phosphorylation cascades, and then ß-Catenin transduces these signals to the nucleus to activate Zfp503 transcription. The transcriptional repressor ZFP503 inhibits the transcription of glial fibrillary acidic protein (Gfap) by binding to the Gfap promoter with the assistance of Grg5. Furthermore, Cd93 knockout mice exhibit autism-like behaviors. Taken together, our results reveal that CD93 is a negative regulator of the onset of astrogenesis and provide insight into therapy for psychiatric disorders.


Assuntos
Astrócitos/fisiologia , Proteínas da Matriz Extracelular/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Glicoproteínas de Membrana/metabolismo , Subfamília D de Receptores Semelhantes a Lectina de Células NK/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Animais , Transtorno Autístico , Córtex Cerebral/citologia , Córtex Cerebral/embriologia , Eletroporação , Proteínas da Matriz Extracelular/genética , Feminino , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Inflamação , Peptídeos e Proteínas de Sinalização Intercelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/genética , Glicoproteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos ICR , Subfamília D de Receptores Semelhantes a Lectina de Células NK/genética , Proteínas do Tecido Nervoso/genética , Neurogênese , Neuroglia , Gravidez
17.
J Neurosci ; 40(15): 3052-3062, 2020 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-32132265

RESUMO

Maintenance of cardiorespiratory homeostasis depends on autonomic reflexes controlled by neuronal circuits of the brainstem. The neurophysiology and neuroanatomy of these reflex pathways are well understood, however, the mechanisms and functional significance of autonomic circuit modulation by glial cells remain largely unknown. In the experiments conducted in male laboratory rats we show that astrocytes of the nucleus of the solitary tract (NTS), the brain area that receives and integrates sensory information from the heart and blood vessels, respond to incoming afferent inputs with [Ca2+]i elevations. Astroglial [Ca2+]i responses are triggered by transmitters released by vagal afferents, glutamate acting at AMPA receptors and 5-HT acting at 5-HT2A receptors. In conscious freely behaving animals blockade of Ca2+-dependent vesicular release mechanisms in NTS astrocytes by virally driven expression of a dominant-negative SNARE protein (dnSNARE) increased baroreflex sensitivity by 70% (p < 0.001). This effect of compromised astroglial function was specific to the NTS as expression of dnSNARE in astrocytes of the ventrolateral brainstem had no effect. ATP is considered the principle gliotransmitter and is released by vesicular mechanisms blocked by dnSNARE expression. Consistent with this hypothesis, in anesthetized rats, pharmacological activation of P2Y1 purinoceptors in the NTS decreased baroreflex gain by 40% (p = 0.031), whereas blockade of P2Y1 receptors increased baroreflex gain by 57% (p = 0.018). These results suggest that glutamate and 5-HT, released by NTS afferent terminals, trigger Ca2+-dependent astroglial release of ATP to modulate baroreflex sensitivity via P2Y1 receptors. These data add to the growing body of evidence supporting an active role of astrocytes in brain information processing.SIGNIFICANCE STATEMENT Cardiorespiratory reflexes maintain autonomic balance and ensure cardiovascular health. Impaired baroreflex may contribute to the development of cardiovascular disease and serves as a robust predictor of cardiovascular and all-cause mortality. The data obtained in this study suggest that astrocytes are integral components of the brainstem mechanisms that process afferent information and modulate baroreflex sensitivity via the release of ATP. Any condition associated with higher levels of "ambient" ATP in the NTS would be expected to decrease baroreflex gain by the mechanism described here. As ATP is the primary signaling molecule of glial cells (astrocytes, microglia), responding to metabolic stress and inflammatory stimuli, our study suggests a plausible mechanism of how the central component of the baroreflex is affected in pathological conditions.


Assuntos
Astrócitos/fisiologia , Barorreflexo/fisiologia , Núcleo Solitário/fisiologia , Trifosfato de Adenosina/fisiologia , Animais , Sinalização do Cálcio/fisiologia , Masculino , Neurônios Aferentes/metabolismo , Neurotransmissores/metabolismo , Neurotransmissores/fisiologia , Agonistas do Receptor Purinérgico P2Y/farmacologia , Antagonistas do Receptor Purinérgico P2Y/farmacologia , Ratos , Ratos Sprague-Dawley , Receptor 5-HT2A de Serotonina/efeitos dos fármacos , Receptores de AMPA/efeitos dos fármacos , Receptores Purinérgicos P2Y1/efeitos dos fármacos , Proteínas SNARE/fisiologia , Serotonina/farmacologia , Estimulação do Nervo Vago
18.
Sci Rep ; 10(1): 5137, 2020 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-32198485

RESUMO

While astrocytes have been traditionally described as passive supportive cells, studies during the last decade have shown they are active players in many aspects of CNS physiology and function both in normal and disease states. However, the precise mechanisms regulating astrocytes function and interactions within the CNS are still poorly understood. This knowledge gap is due in large part to the limitations of current image analysis tools that cannot process astrocyte images efficiently and to the lack of methods capable of quantifying their complex morphological characteristics. To provide an unbiased and accurate framework for the quantitative analysis of fluorescent images of astrocytes, we introduce a new automated image processing pipeline whose main novelties include an innovative module for cell detection based on multiscale directional filters and a segmentation routine that leverages deep learning and sparse representations to reduce the need of training data and improve performance. Extensive numerical tests show that our method performs very competitively with respect to state-of-the-art methods also in challenging images where astrocytes are clustered together. Our code is released open source and freely available to the scientific community.


Assuntos
Astrócitos/fisiologia , Encéfalo/citologia , Encéfalo/fisiologia , Aprendizado Profundo , Processamento de Imagem Assistida por Computador/métodos , Algoritmos , Humanos , Redes Neurais de Computação
19.
Pak J Pharm Sci ; 33(1(Spec)): 469-479, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-32173645

RESUMO

Qingxuan Jiangya Decoction (QXJYD), prescribed by academician Ke-ji Chen, has long been used as a Traditional Chinese Medicine formula in blood pressure control and has achieved good clinical outcomes in hypertensive patients. Qingda granules (QDGs), which is a formula simplified from QXJYD, might serve as a novel anti-hypertensive pharmaceutical. However, the functional mechanism of QDGs remains unclear. This study aimed to evaluate the effect of QDGs against the elevation of blood pressure, systemic inflammation and brain injury in Ang II-mediated hypertensive mice. Ang II-mediated hypertensive mice were treated with 28.63mg QDG of per mouse every day. The blood pressure of all mice was measured on days 0, 1, 3, 5, 7, 14 and 28 by using the tail-cuff plethysmograph method. Following 28 days of treatment, the mice were sacrificed and their whole blood and brain tissues were used for analysis. The results showed that QDGs significantly decreased elevated systolic and diastolic blood pressure in Ang II-mediated hypertensive mice while body weight did not change, which demonstrated anti-hypertensive activities of QDGs without obvious toxicity. QDGs significantly attenuated the level of serum cytokines (IL-6, TNF-a) and chemokines (MCP-1, MIP-1a, RANTES) in the Ang II-mediated hypertensive mice. Moreover, pathological staining showed that QDGs significantly ameliorated cerebral histopathology changes, reduced the loss of neurons and activations of astrocytes. Additionally, QDGs inhibited neuronal apoptosis by down-regulation of Bax expression and up-regulation of Bcl-2 expression. These results suggested that QDGs exhibited excellent anti-hypertensive properties by preventing systemic inflammation and providing neuroprotective effects against Ang II-mediated hypertension.


Assuntos
Angiotensina II/farmacologia , Medicamentos de Ervas Chinesas/farmacologia , Hipertensão/tratamento farmacológico , Inflamação/prevenção & controle , Fármacos Neuroprotetores/farmacologia , Animais , Apoptose/efeitos dos fármacos , Astrócitos/efeitos dos fármacos , Astrócitos/fisiologia , Encéfalo/patologia , Hipertensão/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL
20.
J Neurosci ; 40(11): 2371-2380, 2020 03 11.
Artigo em Inglês | MEDLINE | ID: mdl-32047056

RESUMO

Chronic electroencephalography (EEG) is a widely used tool for monitoring cortical electrical activity in experimental animals. Although chronic implants allow for high-quality, long-term recordings in preclinical studies, the electrodes are foreign objects and might therefore be expected to induce a local inflammatory response. We here analyzed the effects of chronic cranial electrode implantation on glymphatic fluid transport and in provoking structural changes in the meninges and cerebral cortex of male and female mice. Immunohistochemical analysis of brain tissue and dura revealed reactive gliosis in the cortex underlying the electrodes and extensive meningeal lymphangiogenesis in the surrounding dura. Meningeal lymphangiogenesis was also evident in mice prepared with the commonly used chronic cranial window. Glymphatic influx of a CSF tracer was significantly enhanced at 30 d postsurgery in both awake and ketamine-xylazine anesthetized mice with electrodes, supporting the concept that glymphatic influx and intracranial lymphatic drainage are interconnected. Altogether, the experimental results provide clear evidence that chronic implantation of EEG electrodes is associated with significant changes in the brain's fluid transport system. Future studies involving EEG recordings and chronic cranial windows must consider the physiological consequences of cranial implants, which include glial scarring, meningeal lymphangiogenesis, and increased glymphatic activity.SIGNIFICANCE STATEMENT This study shows that implantation of extradural electrodes provokes meningeal lymphangiogenesis, enhanced glymphatic influx of CSF, and reactive gliosis. The analysis based on CSF tracer injection in combination with immunohistochemistry showed that chronically implanted electroencephalography electrodes were surrounded by lymphatic sprouts originating from lymphatic vasculature along the dural sinuses and the middle meningeal artery. Likewise, chronic cranial windows provoked lymphatic sprouting. Tracer influx assessed in coronal slices was increased in agreement with previous reports identifying a close association between glymphatic activity and the meningeal lymphatic vasculature. Lymphangiogenesis in the meninges and altered glymphatic fluid transport after electrode implantation have not previously been described and adds new insights to the foreign body response of the CNS.


Assuntos
Dura-Máter/metabolismo , Eletrodos Implantados/efeitos adversos , Reação a Corpo Estranho/etiologia , Gliose/etiologia , Sistema Glinfático/fisiologia , Linfangiogênese , Animais , Astrócitos/fisiologia , Córtex Cerebral/patologia , Líquido Cefalorraquidiano/fisiologia , Dura-Máter/patologia , Eletroencefalografia/instrumentação , Feminino , Reação a Corpo Estranho/metabolismo , Gliose/metabolismo , Gliose/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microglia/fisiologia , Técnica de Janela Cutânea , Fases do Sono/fisiologia
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