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1.
Nat Commun ; 11(1): 3744, 2020 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-32719346

RESUMO

Epilepsy and autism spectrum disorders (ASD) are two distinct brain disorders but have a high rate of co-occurrence, suggesting shared pathogenic mechanisms. Neuroligins are cell adhesion molecules important in synaptic function and ASD, but their role in epilepsy remains unknown. In this study, we show that Neuroligin 2 (NLG2) knockout mice exhibit abnormal spike and wave discharges (SWDs) and behavioral arrests characteristic of absence seizures. The anti-absence seizure drug ethosuximide blocks SWDs and rescues behavioral arrests and social memory impairment in the knockout mice. Restoring GABAergic transmission either by optogenetic activation of the thalamic reticular nucleus (nRT) presynaptic terminals or postsynaptic NLG2 expression in the thalamic neurons reduces the SWDs and behavioral arrests in the knockout mice. These results indicate that NLG2-mediated GABAergic transmission at the nRT-thalamic circuit represents a common mechanism underlying both epileptic seizures and ASD.


Assuntos
Comportamento Animal , Moléculas de Adesão Celular Neuronais/metabolismo , Epilepsia Tipo Ausência/metabolismo , Epilepsia Tipo Ausência/fisiopatologia , Neurônios GABAérgicos/metabolismo , Rede Nervosa/fisiopatologia , Proteínas do Tecido Nervoso/metabolismo , Transmissão Sináptica , Tálamo/fisiopatologia , Potenciais de Ação , Animais , Ansiedade/fisiopatologia , Eletrodos , Eletroencefalografia , Eletromiografia , Etossuximida , Núcleos Intralaminares do Tálamo/fisiopatologia , Locomoção , Memória , Camundongos Endogâmicos C57BL , Camundongos Knockout
2.
Proc Natl Acad Sci U S A ; 117(27): 15620-15631, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32576689

RESUMO

Repulsive guidance molecules (RGMs) are cell surface proteins that regulate the development and homeostasis of many tissues and organs, including the nervous, skeletal, and immune systems. They control fundamental biological processes, such as migration and differentiation by direct interaction with the Neogenin (NEO1) receptor and function as coreceptors for the bone morphogenetic protein (BMP)/growth differentiation factor (GDF) family. We determined crystal structures of all three human RGM family members in complex with GDF5, as well as the ternary NEO1-RGMB-GDF5 assembly. Surprisingly, we show that all three RGMs inhibit GDF5 signaling, which is in stark contrast to RGM-mediated enhancement of signaling observed for other BMPs, like BMP2. Despite their opposite effect on GDF5 signaling, RGMs occupy the BMP type 1 receptor binding site similar to the observed interactions in RGM-BMP2 complexes. In the NEO1-RGMB-GDF5 complex, RGMB physically bridges NEO1 and GDF5, suggesting cross-talk between the GDF5 and NEO1 signaling pathways. Our crystal structures, combined with structure-guided mutagenesis of RGMs and BMP ligands, binding studies, and cellular assays suggest that RGMs inhibit GDF5 signaling by competing with GDF5 type 1 receptors. While our crystal structure analysis and in vitro binding data initially pointed towards a simple competition mechanism between RGMs and type 1 receptors as a possible basis for RGM-mediated GDF5 inhibition, further experiments utilizing BMP2-mimicking GDF5 variants clearly indicate a more complex mechanism that explains how RGMs can act as a functionality-changing switch for two structurally and biochemically similar signaling molecules.


Assuntos
Moléculas de Adesão Celular Neuronais/metabolismo , Proteínas Ligadas por GPI/metabolismo , Fator 5 de Diferenciação de Crescimento/metabolismo , Proteína da Hemocromatose/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Proteína Morfogenética Óssea 2/metabolismo , Proteína Morfogenética Óssea 2/ultraestrutura , Moléculas de Adesão Celular Neuronais/ultraestrutura , Cristalografia por Raios X , Proteínas Ligadas por GPI/ultraestrutura , Fator 5 de Diferenciação de Crescimento/ultraestrutura , Proteína da Hemocromatose/ultraestrutura , Proteínas de Membrana/metabolismo , Proteínas de Membrana/ultraestrutura , Proteínas do Tecido Nervoso/ultraestrutura , Domínios Proteicos , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/ultraestrutura , Transdução de Sinais
3.
Nat Commun ; 11(1): 2674, 2020 05 29.
Artigo em Inglês | MEDLINE | ID: mdl-32471987

RESUMO

Increasing evidence indicates that guidance molecules used during development for cellular and axonal navigation also play roles in synapse maturation and homeostasis. In C. elegans the netrin receptor UNC-40/DCC controls the growth of dendritic-like muscle cell extensions towards motoneurons and is required to recruit type A GABA receptors (GABAARs) at inhibitory neuromuscular junctions. Here we show that activation of UNC-40 assembles an intracellular synaptic scaffold by physically interacting with FRM-3, a FERM protein orthologous to FARP1/2. FRM-3 then recruits LIN-2, the ortholog of CASK, that binds the synaptic adhesion molecule NLG-1/Neuroligin and physically connects GABAARs to prepositioned NLG-1 clusters. These processes are orchestrated by the synaptic organizer CePunctin/MADD-4, which controls the localization of GABAARs by positioning NLG-1/neuroligin at synapses and regulates the synaptic content of GABAARs through the UNC-40-dependent intracellular scaffold. Since DCC is detected at GABA synapses in mammals, DCC might also tune inhibitory neurotransmission in the mammalian brain.


Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/metabolismo , Moléculas de Adesão Celular/metabolismo , Receptores de Superfície Celular/metabolismo , Receptores de GABA-A/metabolismo , Transmissão Sináptica/fisiologia , Animais , Orientação de Axônios/fisiologia , Moléculas de Adesão Celular Neuronais/metabolismo , Proteínas do Citoesqueleto/metabolismo , Proteínas de Helminto/metabolismo , Proteínas de Membrana/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Junção Neuromuscular/metabolismo , Sinapses/fisiologia
4.
Neuron ; 106(5): 759-768.e7, 2020 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-32243781

RESUMO

Autism spectrum disorder (ASD) is more prevalent in males; however, the etiology for this sex bias is not well understood. Many mutations on X-linked cell adhesion molecule NLGN4X result in ASD or intellectual disability. NLGN4X is part of an X-Y pair, with NLGN4Y sharing ∼97% sequence homology. Using biochemistry, electrophysiology, and imaging, we show that NLGN4Y displays severe deficits in maturation, surface expression, and synaptogenesis regulated by one amino acid difference with NLGN4X. Furthermore, we identify a cluster of ASD-associated mutations surrounding the critical amino acid in NLGN4X, and these mutations phenocopy NLGN4Y. We show that NLGN4Y cannot compensate for the functional deficits observed in ASD-associated NLGN4X mutations. Altogether, our data reveal a potential pathogenic mechanism for male bias in NLGN4X-associated ASD.


Assuntos
Moléculas de Adesão Celular Neuronais/genética , Cromossomos Humanos X/genética , Cromossomos Humanos Y/genética , Neurônios/metabolismo , Transtorno do Espectro Autista/genética , Moléculas de Adesão Celular Neuronais/metabolismo , Feminino , Predisposição Genética para Doença , Células HEK293 , Humanos , Células-Tronco Pluripotentes Induzidas , Deficiência Intelectual/genética , Masculino , Mutação , Transporte Proteico/genética
5.
Neuron ; 106(5): 806-815.e6, 2020 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-32209430

RESUMO

During development of the peripheral nervous system (PNS), Schwann-cell-secreted gliomedin induces the clustering of Na+ channels at the edges of each myelin segment to form nodes of Ranvier. Here we show that bone morphogenetic protein-1 (BMP1)/Tolloid (TLD)-like proteinases confine Na+ channel clustering to these sites by negatively regulating the activity of gliomedin. Eliminating the Bmp1/TLD cleavage site in gliomedin or treating myelinating cultures with a Bmp1/TLD inhibitor results in the formation of numerous ectopic Na+ channel clusters along axons that are devoid of myelin segments. Furthermore, genetic deletion of Bmp1 and Tll1 genes in mice using a Schwann-cell-specific Cre causes ectopic clustering of nodal proteins, premature formation of heminodes around early ensheathing Schwann cells, and altered nerve conduction during development. Our results demonstrate that by inactivating gliomedin, Bmp1/TLD functions as an additional regulatory mechanism to ensure the correct spatial and temporal assembly of PNS nodes of Ranvier.


Assuntos
Proteína Morfogenética Óssea 1/genética , Moléculas de Adesão Celular Neuronais/metabolismo , Bainha de Mielina/metabolismo , Nós Neurofibrosos/metabolismo , Metaloproteases Semelhantes a Toloide/genética , Canais de Sódio Disparados por Voltagem/metabolismo , Animais , Proteína Morfogenética Óssea 1/metabolismo , Camundongos , Camundongos Knockout , Condução Nervosa , Sistema Nervoso Periférico , Transporte Proteico , Células de Schwann/metabolismo , Metaloproteases Semelhantes a Toloide/metabolismo
6.
Nat Commun ; 11(1): 1457, 2020 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-32193381

RESUMO

While several clathrin-independent endocytic processes have been described so far, their biological relevance often remains elusive, especially in pathophysiological contexts such as cancer. In this study, we find that the tumor marker CD166/ALCAM (Activated Leukocyte Cell Adhesion Molecule) is a clathrin-independent cargo. We show that endophilin-A3-but neither A1 nor A2 isoforms-functionally associates with CD166-containing early endocytic carriers and physically interacts with the cargo. Our data further demonstrates that the three endophilin-A isoforms control the uptake of distinct subsets of cargoes. In addition, we provide strong evidence that the construction of endocytic sites from which CD166 is taken up in an endophilin-A3-dependent manner is driven by extracellular galectin-8. Taken together, our data reveal the existence of a previously uncharacterized clathrin-independent endocytic modality, that modulates the abundance of CD166 at the cell surface, and regulates adhesive and migratory properties of cancer cells.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Antígenos CD/metabolismo , Moléculas de Adesão Celular Neuronais/metabolismo , Endocitose , Proteínas Fetais/metabolismo , Galectinas/metabolismo , Neoplasias/patologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Adesão Celular , Linhagem Celular Tumoral , Membrana Celular/metabolismo , Movimento Celular , Chlorocebus aethiops , Clatrina/metabolismo , Fibroblastos , Galectinas/genética , Técnicas de Silenciamento de Genes , Humanos , Microscopia Intravital , Camundongos , RNA Interferente Pequeno , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
7.
J Neurosci ; 40(14): 2817-2827, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32122953

RESUMO

Perturbations to postsynaptic glutamate receptors (GluRs) trigger retrograde signaling to precisely increase presynaptic neurotransmitter release, maintaining stable levels of synaptic strength, a process referred to as homeostatic regulation. However, the structural change of homeostatic regulation remains poorly defined. At wild-type Drosophila neuromuscular junction synapse, there is one Bruchpilot (Brp) ring detected by superresolution microscopy at active zones (AZs). In the present study, we report multiple Brp rings (i.e., multiple T-bars seen by electron microscopy) at AZs of both male and female larvae when GluRs are reduced. At GluRIIC-deficient neuromuscular junctions, quantal size was reduced but quantal content was increased, indicative of homeostatic presynaptic potentiation. Consistently, multiple Brp rings at AZs were observed in the two classic synaptic homeostasis models (i.e., GluRIIA mutant and pharmacological blockade of GluRIIA activity). Furthermore, postsynaptic overexpression of the cell adhesion protein Neuroligin 1 partially rescued multiple Brp rings phenotype. Our study thus supports that the formation of multiple Brp rings at AZs might be a structural basis for synaptic homeostasis.SIGNIFICANCE STATEMENT Synaptic homeostasis is a conserved fundamental mechanism to maintain efficient neurotransmission of neural networks. Active zones (AZs) are characterized by an electron-dense cytomatrix, which is largely composed of Bruchpilot (Brp) at the Drosophila neuromuscular junction synapses. It is not clear how the structure of AZs changes during homeostatic regulation. To address this question, we examined the structure of AZs by superresolution microscopy and electron microscopy during homeostatic regulation. Our results reveal multiple Brp rings at AZs of glutamate receptor-deficient neuromuscular junction synapses compared with single Brp ring at AZs in wild type (WT). We further show that Neuroligin 1-mediated retrograde signaling regulates multiple Brp ring formation at glutamate receptor-deficient synapses. This study thus reveals a regulatory mechanism for synaptic homeostasis.


Assuntos
Homeostase/fisiologia , Junção Neuromuscular/fisiologia , Junção Neuromuscular/ultraestrutura , Sinapses/metabolismo , Sinapses/ultraestrutura , Transmissão Sináptica/fisiologia , Animais , Moléculas de Adesão Celular Neuronais/metabolismo , Drosophila , Proteínas de Drosophila/metabolismo , Feminino , Masculino , Receptores de Glutamato/metabolismo
8.
Bratisl Lek Listy ; 121(2): 107-110, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32115961

RESUMO

AIM: Diabetes is one of the most common diseases which can attenuate brain function by destroying hippocampus neurons, while reelin is a largely secreted extracellular matrix glycoprotein in the hippocampus causing synaptic plasticity, promoting postsynaptic structures and maturing neurons. The aim of this study was to assess the effect of exercise, as an external factor for neurogenesis in the brain, on reelin levels and memory improvement in diabetic rats. METHOD: Thirty rats were randomly allocated into three groups; healthy sedentary, diabetic sedentary and diabetic exercise-trained. The experimental group was treadmill-exercised at speed 22 m/min for 1 hour, 5 days per week. Finally, spatial memory of rats was tested and reelin levels were measured. RESULTS: The results showed that short-term exercise improved spatial memory in diabetic rats but had no effect on reelin levels in the hippocampus of diabetic rats. CONCLUSION: Diabetes reduced the spatial memory without altering the reelin levels while exercise improved spatial memory without altering the reelin levels (Fig. 4, Ref. 33).


Assuntos
Moléculas de Adesão Celular Neuronais/metabolismo , Diabetes Mellitus Experimental , Proteínas da Matriz Extracelular/metabolismo , Hipocampo , Proteínas do Tecido Nervoso/metabolismo , Condicionamento Físico Animal , Serina Endopeptidases/metabolismo , Memória Espacial , Animais , Hipocampo/metabolismo , Neurogênese , Plasticidade Neuronal , Ratos
9.
Nat Commun ; 11(1): 1092, 2020 02 27.
Artigo em Inglês | MEDLINE | ID: mdl-32107390

RESUMO

Micro(mi)RNA-based post-transcriptional regulatory mechanisms have been broadly implicated in the assembly and modulation of synaptic connections required to shape neural circuits, however, relatively few specific miRNAs have been identified that control synapse formation. Using a conditional transgenic toolkit for competitive inhibition of miRNA function in Drosophila, we performed an unbiased screen for novel regulators of synapse morphogenesis at the larval neuromuscular junction (NMJ). From a set of ten new validated regulators of NMJ growth, we discovered that miR-34 mutants display synaptic phenotypes and cell type-specific functions suggesting distinct downstream mechanisms in the presynaptic and postsynaptic compartments. A search for conserved downstream targets for miR-34 identified the junctional receptor CNTNAP4/Neurexin-IV (Nrx-IV) and the membrane cytoskeletal effector Adducin/Hu-li tai shao (Hts) as proteins whose synaptic expression is restricted by miR-34. Manipulation of miR-34, Nrx-IV or Hts-M function in motor neurons or muscle supports a model where presynaptic miR-34 inhibits Nrx-IV to influence active zone formation, whereas, postsynaptic miR-34 inhibits Hts to regulate the initiation of bouton formation from presynaptic terminals.


Assuntos
Proteínas de Ligação a Calmodulina/genética , Moléculas de Adesão Celular Neuronais/genética , Proteínas de Drosophila/genética , Regulação da Expressão Gênica no Desenvolvimento , MicroRNAs/metabolismo , Terminações Pré-Sinápticas/fisiologia , Animais , Animais Geneticamente Modificados , Proteínas de Ligação a Calmodulina/metabolismo , Moléculas de Adesão Celular Neuronais/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/fisiologia , Larva/crescimento & desenvolvimento , Morfogênese/genética , Mutação , Junção Neuromuscular/citologia , Junção Neuromuscular/crescimento & desenvolvimento
10.
Cell Mol Life Sci ; 77(16): 3117-3127, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32077971

RESUMO

Complex brain circuitry with feedforward and feedback systems regulates neuronal activity, enabling neural networks to process and drive the entire spectrum of cognitive, behavioral, sensory, and motor functions. Simultaneous orchestration of distinct cells and interconnected neural circuits is underpinned by hundreds of synaptic adhesion molecules that span synaptic junctions. Dysfunction of a single molecule or molecular interaction at synapses can lead to disrupted circuit activity and brain disorders. Neuroligins, a family of cell adhesion molecules, were first identified as postsynaptic-binding partners of presynaptic neurexins and are essential for synapse specification and maturation. Here, we review recent advances in our understanding of how this family of adhesion molecules controls neuronal circuit assembly by acting in a synapse-specific manner.


Assuntos
Encéfalo/fisiologia , Rede Nervosa/fisiologia , Neurônios/fisiologia , Animais , Encéfalo/metabolismo , Moléculas de Adesão Celular Neuronais/metabolismo , Humanos , Rede Nervosa/metabolismo , Neurônios/metabolismo , Sinapses/metabolismo , Sinapses/fisiologia , Transmissão Sináptica/fisiologia
11.
Neurobiol Aging ; 87: 132-137, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31952867

RESUMO

The glycoprotein reelin has been implicated in both memory-related synaptic plasticity and Alzheimer's disease pathogenesis. Aged rats with memory impairment display decreased reelin expression in layer II of the entorhinal cortex (EC) relative to memory-intact subjects, and here we tested whether this effect extends to the primate brain. Seven young adult (8-10 years) and 14 aged (27-38 years) rhesus monkeys (Macaca mulatta) were examined, including 7 old animals classified as impaired based on their scores from a delayed nonmatching-to-sample recognition memory test. Histological sections spanning the rostrocaudal extent of the intermediate and caudal divisions of EC were processed by immunohistochemistry and the total number of reelin-positive neurons in layer II was estimated using design-based stereological techniques. The main finding was that the number of reelin-expressing neurons in EC layer II is decreased selectively in aged monkeys with memory deficits relative to young adult and aged subjects with intact memory. The results add to evidence implicating EC-hippocampal integrity in neurocognitive aging, and they suggest that disrupted reelin signaling may be among the mechanisms that mediate the associated vulnerability of this circuitry in Alzheimer's disease.


Assuntos
Moléculas de Adesão Celular Neuronais/metabolismo , Córtex Entorrinal/metabolismo , Córtex Entorrinal/patologia , Proteínas da Matriz Extracelular/metabolismo , Transtornos da Memória/metabolismo , Transtornos da Memória/patologia , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismo , Neurônios/patologia , Serina Endopeptidases/metabolismo , Doença de Alzheimer/etiologia , Doença de Alzheimer/patologia , Animais , Envelhecimento Cognitivo , Macaca mulatta , Transtornos da Memória/etiologia , Ratos , Transdução de Sinais/genética , Transdução de Sinais/fisiologia
12.
Chemistry ; 26(8): 1834-1845, 2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-31773792

RESUMO

Chemical chaperones prevent protein aggregation. However, the use of chemical chaperones as drugs against diseases due to protein aggregation is limited by the very high active concentrations (mm range) required to mediate their effect. One of the most common chemical chaperones is 4-phenylbutyric acid (4-PBA). Despite its unfavorable pharmacokinetic properties, 4-PBA was approved as a drug to treat ornithine cycle diseases. Here, we report that 2-isopropyl-4-phenylbutanoic acid (5) has been found to be 2-10-fold more effective than 4-PBA in several in vitro models of protein aggregation. Importantly, compound 5 reduced the secretion rate of autism-linked Arg451Cys Neuroligin3 (R451C NLGN3).


Assuntos
Fenilbutiratos/química , Proteínas/química , Animais , Moléculas de Adesão Celular Neuronais/química , Moléculas de Adesão Celular Neuronais/genética , Moléculas de Adesão Celular Neuronais/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Células HEK293 , Humanos , Proteínas de Membrana/química , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Mutagênese Sítio-Dirigida , Proteínas do Tecido Nervoso/química , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Células PC12 , Fenilbutiratos/farmacologia , Agregados Proteicos/efeitos dos fármacos , Dobramento de Proteína , Proteínas/metabolismo , Ratos
13.
Methods Mol Biol ; 2043: 93-104, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31463905

RESUMO

Reelin is a large secreted protein that is essential for the brain development and function. Reelin is negatively regulated by the specific cleavage by a disintegrin and metalloproteinase with thrombospondin type 1 motifs 3 (ADAMTS-3) which is also secreted from neurons. It is likely that there are other proteases that can cleave Reelin. This chapter describes the protocol for expression and handling of recombinant Reelin and ADAMTS-3 proteins to facilitate investigation of these proteins.


Assuntos
Proteínas ADAMTS/genética , Moléculas de Adesão Celular Neuronais/genética , Proteínas da Matriz Extracelular/genética , Expressão Gênica , Proteínas do Tecido Nervoso/genética , Pró-Colágeno N-Endopeptidase/genética , Serina Endopeptidases/genética , Proteínas ADAMTS/metabolismo , Moléculas de Adesão Celular Neuronais/metabolismo , Proteínas da Matriz Extracelular/metabolismo , Células HEK293 , Humanos , Proteínas do Tecido Nervoso/metabolismo , Pró-Colágeno N-Endopeptidase/metabolismo , Engenharia de Proteínas , Proteínas Recombinantes/metabolismo , Serina Endopeptidases/metabolismo
14.
Sci Total Environ ; 700: 134492, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31627046

RESUMO

Graphene oxide (GO) is a carbon-based engineered nanomaterial (ENM). Using Caenorhabditis elegans as an animal model, we investigated the effect of GO exposure on protein-protein interactions. In nematodes, NLG-1/Neuroligin, a postsynaptic protein, acted only in the neurons to regulate the GO toxicity. In the neurons, DLG-1, a PSD-95 protein, and MAGI-1, a S-SCAM protein, were identified as the downstream targets of NLG-1 in the regulation of GO toxicity. PKC-1, a serine/threonine protein kinase C, further acted downstream of neuronal DLG-1 and MAGI-1 to regulate the GO toxicity. Co-immunoprecipitation analysis demonstrated the protein-protein interaction between NLG-1 and DLG-1 or MAGI-1. After GO expression, this protein-protein interaction between NLG-1 and DLG-1 or MAGI-1 was significantly inhibited. Therefore, our data raised the evidence to suggest the potential of GO exposure in disrupting protein-protein interactions in organisms.


Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/fisiologia , Grafite/toxicidade , Substâncias Perigosas/toxicidade , Animais , Moléculas de Adesão Celular Neuronais/metabolismo , Guanilato Quinases
15.
Development ; 147(2)2020 01 22.
Artigo em Inglês | MEDLINE | ID: mdl-31862845

RESUMO

The development of tissues and organs requires close interaction of cells. To achieve this, cells express adhesion proteins such as the neural cell adhesion molecule (NCAM) or its Drosophila ortholog Fasciclin 2 (Fas2). Both are members of the Ig-domain superfamily of proteins that mediate homophilic adhesion. These proteins are expressed as isoforms differing in their membrane anchorage and their cytoplasmic domains. To study the function of single isoforms, we have conducted a comprehensive genetic analysis of F as2 We reveal the expression pattern of all major Fas2 isoforms, two of which are GPI anchored. The remaining five isoforms carry transmembrane domains with variable cytoplasmic tails. We generated F as2 mutants expressing only single isoforms. In contrast to the null mutation, which causes embryonic lethality, these mutants are viable, indicating redundancy among the different isoforms. Cell type-specific rescue experiments showed that glial-secreted Fas2 can rescue the F as2 mutant phenotype to viability. This demonstrates that cytoplasmic Fas2 domains have no apparent essential functions and indicate that Fas2 has function(s) other than homophilic adhesion. In conclusion, our data suggest novel mechanistic aspects of a long-studied adhesion protein.


Assuntos
Moléculas de Adesão Celular Neuronais/metabolismo , Drosophila melanogaster/citologia , Drosophila melanogaster/metabolismo , Transdução de Sinais , Animais , Adesão Celular , Moléculas de Adesão Celular Neuronais/química , Moléculas de Adesão Celular Neuronais/genética , Movimento Celular , Drosophila melanogaster/embriologia , Drosophila melanogaster/genética , Embrião não Mamífero/citologia , Embrião não Mamífero/metabolismo , Edição de Genes , Regulação da Expressão Gênica no Desenvolvimento , Glicosilfosfatidilinositóis/metabolismo , Mutação/genética , Neuroglia/metabolismo , Domínios Proteicos , Isoformas de Proteínas/metabolismo , Traqueia/embriologia , Traqueia/metabolismo
16.
Neurol India ; 67(6): 1469-1471, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31857537

RESUMO

Objective: To study the DNA methylation profiles in brain tissue of patients with refractory epilepsy due to malformations of cortical development (MCDs). Materials and Methods: Clinical, neuroimaging, and pathology characteristics were defined for 13 patients who underwent resective surgery for epilepsy. Methylation analysis was performed using Illumina® 450k Methylation Microarray. Data analysis was completed, and pathway identification was done using the R/Bioconductor package. Results: Genes associated with Ephrin-Reelin pathway, potassium channels, and glutathione metabolism were differentially methylated in the MCD group when compared with patients who had no evidence of MCD. Conclusions: Our preliminary data reveal that epigenetic pathways may have a role in the pathobiogenesis of MCDs.


Assuntos
Encéfalo/metabolismo , Metilação de DNA , Epilepsia/genética , Malformações do Desenvolvimento Cortical/genética , Encéfalo/diagnóstico por imagem , Encéfalo/cirurgia , Moléculas de Adesão Celular Neuronais/genética , Moléculas de Adesão Celular Neuronais/metabolismo , Criança , Pré-Escolar , Epilepsia/etiologia , Epilepsia/cirurgia , Proteínas da Matriz Extracelular/genética , Proteínas da Matriz Extracelular/metabolismo , Feminino , Humanos , Lactente , Masculino , Malformações do Desenvolvimento Cortical/complicações , Malformações do Desenvolvimento Cortical/cirurgia , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Projetos Piloto , Canais de Potássio/genética , Canais de Potássio/metabolismo , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismo , Transdução de Sinais/genética
17.
Yakugaku Zasshi ; 139(11): 1397-1402, 2019.
Artigo em Japonês | MEDLINE | ID: mdl-31685736

RESUMO

Patients with epilepsy are often affected by not only seizures but also a variety of cognitive and psychiatric comorbidities that further impair their quality of life. However, it is unclear whether epilepsy is associated with psychic function. The aim of the present study was to clarify the effects of kindling-induced epileptic seizures on psychic functioning, using behavioral pharmacological tests. Pentylenetetrazol (PTZ)-kindled mice displayed impaired motor coordination (in the rotarod test), and social approach impairment (in the three-chamber social test) compared with vehicle mice. Intraperitoneal ABT-418 treatment (0.05 mg/kg) alleviated these behavioral abnormalities in PTZ-kindled mice. Immunolabeling of tissue sections demonstrated that expression of the α4 subunit of the α4ß2 nicotinic acetylcholine receptor in the piriform cortex was significantly decreased in PTZ-kindled mice. In contrast, expression of the synaptic adhesion molecule neuroligin 3 (NLG3) was significantly higher in the piriform cortex of PTZ-kindled mice compared with vehicle mice. Collectively, our findings suggest that attention deficit/hyperactivity disorder (ADHD)-like or autistic-like behavioral abnormalities associated with epilepsy are closely linked to downregulation of the α4 subunit of the α4ß2 receptor and upregulation of NLG3 in the mouse piriform cortex. In summary, this study indicates that ABT-418 is a good candidate for the treatment of patients with epilepsy complicated by psychiatric symptoms such as autism and ADHD.


Assuntos
Epilepsia/psicologia , Excitação Neurológica , Transtornos Mentais/tratamento farmacológico , Transtornos Mentais/etiologia , Pentilenotetrazol , Receptores Nicotínicos/metabolismo , Convulsões/psicologia , Animais , Moléculas de Adesão Celular Neuronais/metabolismo , Modelos Animais de Doenças , Regulação para Baixo , Epilepsia/induzido quimicamente , Epilepsia/tratamento farmacológico , Epilepsia/etiologia , Isoxazóis/farmacologia , Isoxazóis/uso terapêutico , Proteínas de Membrana/metabolismo , Camundongos , Proteínas do Tecido Nervoso/metabolismo , Córtex Piriforme/metabolismo , Desempenho Psicomotor/efeitos dos fármacos , Pirrolidinas/farmacologia , Pirrolidinas/uso terapêutico , Qualidade de Vida , Convulsões/induzido quimicamente , Convulsões/tratamento farmacológico , Convulsões/etiologia , Comportamento Social
18.
Nat Commun ; 10(1): 4794, 2019 10 22.
Artigo em Inglês | MEDLINE | ID: mdl-31641127

RESUMO

Central nervous system myelin is a multilayered membrane produced by oligodendrocytes to increase neural processing speed and efficiency, but the molecular mechanisms underlying axonal selection and myelin wrapping are unknown. Here, using combined morphological and molecular analyses in mice and zebrafish, we show that adhesion molecules of the paranodal and the internodal segment work synergistically using overlapping functions to regulate axonal interaction and myelin wrapping. In the absence of these adhesive systems, axonal recognition by myelin is impaired with myelin growing on top of previously myelinated fibers, around neuronal cell bodies and above nodes of Ranvier. In addition, myelin wrapping is disturbed with the leading edge moving away from the axon and in between previously formed layers. These data show how two adhesive systems function together to guide axonal ensheathment and myelin wrapping, and provide a mechanistic understanding of how the spatial organization of myelin is achieved.


Assuntos
Axônios/fisiologia , Sistema Nervoso Central/fisiologia , Bainha de Mielina/fisiologia , Moléculas de Adesão de Célula Nervosa/metabolismo , Animais , Animais Geneticamente Modificados , Adesão Celular/fisiologia , Moléculas de Adesão Celular Neuronais/genética , Moléculas de Adesão Celular Neuronais/metabolismo , Contactina 1/genética , Contactina 1/metabolismo , Feminino , Larva , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Bainha de Mielina/patologia , Glicoproteína Associada a Mielina/genética , Glicoproteína Associada a Mielina/metabolismo , Moléculas de Adesão de Célula Nervosa/genética , Nervo Óptico/metabolismo , Nervo Óptico/patologia , Peixe-Zebra/genética , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismo
19.
Elife ; 82019 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-31577229

RESUMO

The functions of FGF receptors (FGFRs) in early development of the cerebral cortex are well established. Their functions in the migration of neocortical projection neurons, however, are unclear. We have found that FGFRs regulate multipolar neuron orientation and the morphological change into bipolar cells necessary to enter the cortical plate. Mechanistically, our results suggest that FGFRs are activated by N-Cadherin. N-Cadherin cell-autonomously binds FGFRs and inhibits FGFR K27- and K29-linked polyubiquitination and lysosomal degradation. Accordingly, FGFRs accumulate and stimulate prolonged Erk1/2 phosphorylation. Neurons inhibited for Erk1/2 are stalled in the multipolar zone. Moreover, Reelin, a secreted protein regulating neuronal positioning, prevents FGFR degradation through N-Cadherin, causing Erk1/2 phosphorylation. These findings reveal novel functions for FGFRs in cortical projection neuron migration, suggest a physiological role for FGFR and N-Cadherin interaction in vivo and identify Reelin as an extracellular upstream regulator and Erk1/2 as downstream effectors of FGFRs during neuron migration.


Assuntos
Caderinas/metabolismo , Neocórtex/embriologia , Neurogênese , Neurônios/metabolismo , Receptores de Fatores de Crescimento de Fibroblastos/metabolismo , Ubiquitinação , Animais , Moléculas de Adesão Celular Neuronais/metabolismo , Proteínas da Matriz Extracelular/metabolismo , Sistema de Sinalização das MAP Quinases , Camundongos , Proteínas do Tecido Nervoso/metabolismo , Fosforilação , Serina Endopeptidases/metabolismo
20.
EBioMedicine ; 47: 427-435, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31481324

RESUMO

In recent years molecules involved on the immune synapse became successful targets for therapeutic immune modulation. CD6 has been extensively studied, yet, results regarding CD6 biology have been controversial, in spite of the ubiquitous presence of this molecule on virtually all CD4 T cells. We investigated the outcome of murine and human antibodies targeting CD6 domain 1. We found that CD6-targeting had a major impact on the functional specialization of CD4 cells, both human and murine. Differentiation of CD4 T cells towards a Foxp3+ Treg fate was prevented with increasing doses of anti-CD6, while Th1 polarization was favoured. No impact was observed on Th2 or Th17 specialization. These in vitro results provided an explanation for the dose-dependent outcome of in vivo anti-CD6 administration where the anti-inflammatory action is lost at the highest doses. Our data show that therapeutic targeting of the immune synapse may lead to paradoxical dose-dependent effects due to modification of T cell fate.


Assuntos
Antígenos CD/metabolismo , Antígenos de Diferenciação de Linfócitos T/metabolismo , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Animais , Biomarcadores , Linfócitos T CD4-Positivos/citologia , Moléculas de Adesão Celular Neuronais/metabolismo , Diferenciação Celular , Proteínas Fetais/metabolismo , Humanos , Ativação Linfocitária , Camundongos , Camundongos Transgênicos , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo
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