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1.
Cereb Cortex ; 26(7): 3219-36, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-26209842

RESUMO

Disabled-1 (Dab1) is an essential intracellular protein in the Reelin pathway. It has a nuclear localization signal (NLS; hereafter referred to as "NLS1") and 2 nuclear export signals, and shuttles between the nucleus and the cytoplasm. In this study, we found that Dab1 has an additional unidentified NLS, and that the Dab1 NLS1 mutant could translocate to the nucleus in an unconventional ATP/temperature-dependent and cytoplasmic factor/RanGTP gradient-independent manner. Additional mutations in the NLS1 mutant revealed that K(67) and K(69) are important for the nuclear transport. Furthermore, an excess of the intracellular domain of the Reelin receptors inhibited the nuclear translocation of Dab1. An in utero electroporation study showed that a large amount of Dab1 in the cytoplasm in migrating neurons inhibited the migration, and that forced transport of Dab1 into the nucleus attenuated this inhibitory effect. In addition, rescue experiments using yotari, an autosomal recessive mutant of dab1, revealed that cells expressing Dab1 NLS1 mutant tend to distribute at more superficial positions than those expressing wild-type Dab1. Taken together, these findings suggest that Dab1 has at least 2 NLSs, and that the regulation of the subcellular localization of Dab1 is important for the proper migration of excitatory neurons.


Assuntos
Transporte Ativo do Núcleo Celular/fisiologia , Movimento Celular/fisiologia , Córtex Cerebral/metabolismo , Citoplasma/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Córtex Cerebral/embriologia , Córtex Cerebral/patologia , Citoplasma/patologia , Guanosina Trifosfato/metabolismo , Células HeLa , Humanos , Proteínas Relacionadas a Receptor de LDL/metabolismo , Camundongos Endogâmicos ICR , Camundongos Transgênicos , Mutação , Proteínas do Tecido Nervoso/genética , Neurônios/patologia , Receptores de Superfície Celular/metabolismo , Receptores de LDL/metabolismo , Receptores Notch/metabolismo , Temperatura Ambiente , Proteína ran de Ligação ao GTP/metabolismo
2.
Proc Natl Acad Sci U S A ; 112(36): E4985-94, 2015 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-26305926

RESUMO

The preoptic area (POa) of the rostral diencephalon supplies the neocortex and the amygdala with GABAergic neurons in the developing mouse brain. However, the molecular mechanisms that determine the pathway and destinations of POa-derived neurons have not yet been identified. Here we show that Chicken ovalbumin upstream promoter transcription factor II (COUP-TFII)-induced expression of Neuropilin-2 (Nrp2) and its down-regulation control the destination of POa-derived GABAergic neurons. Initially, a majority of the POa-derived migrating neurons express COUP-TFII and form a caudal migratory stream toward the caudal subpallium. When a subpopulation of cells steers toward the neocortex, they exhibit decreased expression of COUP-TFII and Nrp2. The present findings show that suppression of COUP-TFII/Nrp2 changed the destination of the cells into the neocortex, whereas overexpression of COUP-TFII/Nrp2 caused cells to end up in the medial part of the amygdala. Taken together, these results reveal that COUP-TFII/Nrp2 is a molecular switch determining the pathway and destination of migrating GABAergic neurons born in the POa.


Assuntos
Encéfalo/metabolismo , Fator II de Transcrição COUP/metabolismo , Diencéfalo/metabolismo , Neurônios GABAérgicos/metabolismo , Neuropilina-2/metabolismo , Tonsila do Cerebelo/embriologia , Tonsila do Cerebelo/metabolismo , Animais , Western Blotting , Encéfalo/embriologia , Fator II de Transcrição COUP/genética , Movimento Celular/genética , Diencéfalo/embriologia , Neurônios GABAérgicos/citologia , Regulação da Expressão Gênica no Desenvolvimento , Hibridização In Situ , Camundongos Endogâmicos ICR , Camundongos Knockout , Microscopia Confocal , Neocórtex/embriologia , Neocórtex/metabolismo , Neuropilina-2/genética , Área Pré-Óptica/embriologia , Área Pré-Óptica/metabolismo , Interferência de RNA , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Técnicas de Cultura de Tecidos
3.
J Neurosci ; 35(11): 4776-87, 2015 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-25788693

RESUMO

During brain development, Reelin exerts a variety of effects in a context-dependent manner, whereas its underlying molecular mechanisms remain poorly understood. We previously showed that the C-terminal region (CTR) of Reelin is required for efficient induction of phosphorylation of Dab1, an essential adaptor protein for canonical Reelin signaling. However, the physiological significance of the Reelin CTR in vivo remains unexplored. To dissect out Reelin functions, we made a knock-in (KI) mouse in which the Reelin CTR is deleted. The amount of Dab1, an indication of canonical Reelin signaling strength, is increased in the KI mouse, indicating that the CTR is necessary for efficient induction of Dab1 phosphorylation in vivo. Formation of layer structures during embryonic development is normal in the KI mouse. Intriguingly, the marginal zone (MZ) of the cerebral cortex becomes narrower at postnatal stages because upper-layer neurons invade the MZ and their apical dendrites are misoriented and poorly branched. Furthermore, Reelin undergoes proteolytic cleavage by proprotein convertases at a site located 6 residues from the C terminus, and it was suggested that this cleavage abrogates the Reelin binding to the neuronal cell membrane. Results from ectopic expression of mutant Reelin proteins in utero suggest that the dendrite development and maintenance of the MZ require Reelin protein with an intact CTR. These results provide a novel model regarding Reelin functions involving its CTR, which is not required for neuronal migration during embryonic stages but is required for the development and maintenance of the MZ in the postnatal cerebral cortex.


Assuntos
Moléculas de Adesão Celular Neuronais/genética , Moléculas de Adesão Celular Neuronais/metabolismo , Córtex Cerebral/crescimento & desenvolvimento , Córtex Cerebral/metabolismo , Proteínas da Matriz Extracelular/genética , Proteínas da Matriz Extracelular/metabolismo , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismo , Animais , Células COS , Cercopithecus aethiops , Técnicas de Introdução de Genes/métodos , Células HEK293 , Humanos , Camundongos , Camundongos Endogâmicos ICR , Proteólise
4.
J Comp Neurol ; 523(3): 463-78, 2015 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-25308109

RESUMO

In mammalian developing brain, neuronal migration is regulated by a variety of signaling cascades, including Reelin signaling. Reelin is a glycoprotein that is mainly secreted by Cajal-Retzius neurons in the marginal zone, playing essential roles in the formation of the layered neocortex via its receptors, apolipoprotein E receptor 2 (ApoER2) and very low density lipoprotein receptor (VLDLR). However, the precise mechanisms by which Reelin signaling controls the neuronal migration process remain unclear. To gain insight into how Reelin signaling controls individual migrating neurons, we generated monoclonal antibodies against ApoER2 and VLDLR and examined the localization of Reelin receptors in the developing mouse cerebral cortex. Immunohistochemical analyses revealed that VLDLR is localized to the distal portion of leading processes in the marginal zone (MZ), whereas ApoER2 is mainly localized to neuronal processes and the cell membranes of multipolar cells in the multipolar cell accumulation zone (MAZ). These different expression patterns may contribute to the distinct actions of Reelin on migrating neurons during both the early and late migratory stages in the developing cerebral cortex.


Assuntos
Córtex Cerebral/crescimento & desenvolvimento , Córtex Cerebral/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/genética , Proteínas Relacionadas a Receptor de LDL/metabolismo , Receptores de LDL/metabolismo , Animais , Moléculas de Adesão Celular Neuronais/metabolismo , Proteínas da Matriz Extracelular/metabolismo , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Células HEK293 , Humanos , Proteínas Relacionadas a Receptor de LDL/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Mutantes Neurológicos , Proteínas do Tecido Nervoso/metabolismo , Receptores de Superfície Celular/metabolismo , Receptores de LDL/genética , Serina Endopeptidases/metabolismo , Transfecção
5.
Hum Mol Genet ; 24(6): 1630-45, 2015 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-25398948

RESUMO

The expansion of the GGGGCC hexanucleotide repeat in the non-coding region of the chromosome 9 open-reading frame 72 (C9orf72) gene is the most common cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) (c9FTD/ALS). Recently, it was reported that an unconventional mechanism of repeat-associated non-ATG (RAN) translation arises from C9orf72 expansion. Sense and anti-sense transcripts of the expanded C9orf72 repeat, i.e. the dipeptide repeat protein (DRP) of glycine-alanine (poly-GA), glycine-proline (poly-GP), glycine-arginine (poly-GR), proline-arginine (poly-PR) and proline-alanine (poly-PA), are deposited in the brains of patients with c9FTD/ALS. However, the pathological significance of RAN-translated peptides remains unknown. We generated synthetic cDNAs encoding 100 repeats of DRP without a GGGGCC repeat and evaluated the effects of these proteins on cultured cells and cortical neurons in vivo. Our results revealed that the poly-GA protein formed highly aggregated ubiquitin/p62-positive inclusion bodies in neuronal cells. In contrast, the highly basic proteins poly-GR and PR also formed unique ubiquitin/p62-negative cytoplasmic inclusions, which co-localized with the components of RNA granules. The evaluation of cytotoxicity revealed that overexpressed poly-GA, poly-GP and poly-GR increased the substrates of the ubiquitin-proteasome system (UPS), including TDP-43, and enhanced the sensitivity to a proteasome inhibitor, indicating that these DRPs are cytotoxic, possibly via UPS dysfunction. The present data indicate that a gain-of-function mechanism of toxic DRPs possibly contributes to pathogenesis in c9FTD/ALS and that DRPs may serve as novel therapeutic targets in c9FTD/ALS.


Assuntos
Esclerose Amiotrófica Lateral/genética , Expansão das Repetições de DNA , Demência Frontotemporal/genética , Corpos de Inclusão/metabolismo , Proteínas/genética , Ubiquitina/metabolismo , Animais , Proteína C9orf72 , Cercopithecus aethiops , Córtex Cerebral/fisiopatologia , Demência Frontotemporal/metabolismo , Humanos , Camundongos , Neurônios/patologia , Proteínas/metabolismo , Sequências Repetitivas de Aminoácidos
6.
Neuron ; 76(2): 353-69, 2012 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-23083738

RESUMO

Birthdate-dependent neuronal layering is fundamental to neocortical functions. The extracellular protein Reelin is essential for the establishment of the eventual neuronal alignments. Although this Reelin-dependent neuronal layering is mainly established by the final neuronal migration step called "terminal translocation" beneath the marginal zone (MZ), the molecular mechanism underlying the control by Reelin of terminal translocation and layer formation is largely unknown. Here, we show that after Reelin binds to its receptors, it activates integrin α5ß1 through the intracellular Dab1-Crk/CrkL-C3G-Rap1 pathway. This intracellular pathway is required for terminal translocation and the activation of Reelin signaling promotes neuronal adhesion to fibronectin through integrin α5ß1. Since fibronectin is localized in the MZ, the activated integrin α5ß1 then controls terminal translocation, which mediates proper neuronal alignments in the mature cortex. These data indicate that Reelin-dependent activation of neuronal adhesion to the extracellular matrix is crucial for the eventual birth-date-dependent layering of the neocortex.


Assuntos
Moléculas de Adesão Celular Neuronais/metabolismo , Adesão Celular/fisiologia , Movimento Celular/fisiologia , Proteínas da Matriz Extracelular/metabolismo , Regulação da Expressão Gênica/fisiologia , Integrina alfa5beta1/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Neurônios/fisiologia , Serina Endopeptidases/metabolismo , Proteínas Adaptadoras de Transdução de Sinal , Análise de Variância , Animais , Adesão Celular/efeitos dos fármacos , Adesão Celular/genética , Moléculas de Adesão Celular Neuronais/efeitos dos fármacos , Moléculas de Adesão Celular Neuronais/genética , Linhagem Celular Transformada , Movimento Celular/efeitos dos fármacos , Movimento Celular/genética , Eletroporação , Embrião de Mamíferos , Proteínas da Matriz Extracelular/efeitos dos fármacos , Proteínas da Matriz Extracelular/genética , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Proteínas de Fluorescência Verde/genética , Humanos , Integrina alfa5beta1/genética , Camundongos , Camundongos Endogâmicos ICR , Camundongos Mutantes Neurológicos , Camundongos Transgênicos , Mutação/genética , Proteínas do Tecido Nervoso/efeitos dos fármacos , Proteínas do Tecido Nervoso/genética , Neurônios/efeitos dos fármacos , Proteínas Nucleares , Gravidez , Proteínas Proto-Oncogênicas c-crk/metabolismo , Serina Endopeptidases/efeitos dos fármacos , Serina Endopeptidases/genética , Transdução de Sinais/genética , Transdução de Sinais/fisiologia , Córtex Somatossensorial/citologia , Proteínas rap1 de Ligação ao GTP/metabolismo
7.
Eur J Neurosci ; 36(3): 2284-92, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22612501

RESUMO

Leucine-rich glioma inactivated 1 (Lgi1) is a secreted synaptic protein that organizes a transsynaptic protein complex throughout the brain. Mutations in the Lgi1 gene have been found in patients with autosomal dominant lateral temporal lobe epilepsy (ADLTE). Although a large number of studies have focused on the expression and function of Lgi1 in the postnatal brain, information regarding its functions and distribution during development remains sparse. Here we report that Lgi1 mRNA is preferentially expressed in the caudal ganglionic eminence (CGE) of the early embryonic telencephalon, and LGI1 protein is unexpectedly localized in the nucleus of dissociated CGE neurons. Using bioinformatics analysis, we found that LGI1 contains a putative nuclear localization signal (NLS) in its leucine-rich repeat C-terminal domain. Furthermore, we show that the transient expression of Lgi1 in CGE neurons resulted in nuclear translocation of the LGI1 protein, and a mutation in the NLS led to the retention of LGI1 in the cytoplasm. We also confirmed that the NLS sequence of LGI1 had the ability to mediate the nuclear localization by using the NLS-containing fusion protein. Interestingly, when Lgi1 was expressed in neurons obtained from the medial ganglionic eminence or cerebral cortex, almost no nuclear localization of LGI1 was observed. These results raise the possibility of a novel role of Lgi1 within embryonic neurons through nuclear translocation and may provide insight into its potential effects on the development of the central nervous system and ADLTE pathogenesis.


Assuntos
Núcleo Celular/química , Citosol/química , Neurônios/química , Sinais de Localização Nuclear , Proteínas/análise , Proteínas/química , Telencéfalo/química , Transporte Ativo do Núcleo Celular , Animais , Núcleo Celular/metabolismo , Células Cultivadas , Camundongos , Camundongos Endogâmicos ICR , Camundongos Knockout , Mutação , Neurônios/metabolismo , Sinais de Localização Nuclear/genética , Proteínas/genética , RNA Mensageiro/biossíntese , Telencéfalo/embriologia , Telencéfalo/metabolismo
8.
J Neurosci ; 31(25): 9426-39, 2011 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-21697392

RESUMO

Mammalian neocortex has a laminated structure that develops in a birth-date-dependent "inside-out" pattern. This layered structure is established by neuronal migration with sequential changes of the migratory mode regulated by several signaling cascades, including the Reelin-Disabled homolog 1 (Dab1) pathway. Although the importance of "locomotion," the major migratory mode, has been well established, the physiological significance of the mode change from locomotion to "terminal translocation," the final migratory mode, is unknown. In this study, we found that the outermost region of the mouse cortical plate has several histologically distinct features and named this region the primitive cortical zone (PCZ). Time-lapse analyses revealed that "locomoting" neurons paused transiently just beneath the PCZ before migrating into it by "terminal translocation." Furthermore, whereas Dab1-knockdown (KD) neurons could reach beneath the PCZ, they failed to enter the PCZ, suggesting that the Dab1-dependent terminal translocation is necessary for entry of the neurons into the PCZ. Importantly, sequential in utero electroporation experiments directly revealed that failure of the Dab1-dependent terminal translocation resulted in disruption of the inside-out alignment within the PCZ and that this disrupted pattern was still preserved in the mature cortex. Conversely, Dab1-KD locomoting neurons could pass by both wild-type and Dab1-KD predecessors beneath the PCZ. Our data indicate that the PCZ is a unique environment, passage of neurons through which involves molecularly and behaviorally different migratory mechanisms, and that the migratory mode change from locomotion to terminal translocation just beneath the PCZ is critical for the Dab1-dependent inside-out lamination in the mature cortex.


Assuntos
Morfogênese/fisiologia , Neocórtex/embriologia , Neocórtex/fisiologia , Proteínas do Tecido Nervoso/metabolismo , Neurogênese/fisiologia , Animais , Movimento Celular , Camundongos , Camundongos Endogâmicos ICR , Neurônios/fisiologia
9.
Neurochem Res ; 36(7): 1270-9, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21253854

RESUMO

Reeler is a mutant mouse with defects in layered structures of the central nervous system, such as the cerebral cortex, hippocampus, and cerebellum, and has been extensively examined for more than half a century. The full-length cDNA for the responsible gene for reeler, reelin, was serendipitously identified, revealing that Reelin encodes a large secreted protein. So far, two Reelin receptors, apolipoprotein E receptor 2 and very low-density lipoprotein receptor, and the cytoplasmic adaptor protein Disabled homolog 1 (Dab1) have been shown to be essential for Reelin signaling. Although a number of downstream cascades of Dab1 have also been reported using various experimental systems, the physiological functions of Reelin in vivo remain controversial. Here, we review recent advances in the understanding of the Reelin-Dab1 signaling pathway in the developing cerebral cortex.


Assuntos
Moléculas de Adesão Celular Neuronais/fisiologia , Córtex Cerebral/embriologia , Proteínas da Matriz Extracelular/fisiologia , Proteínas do Tecido Nervoso/fisiologia , Serina Endopeptidases/fisiologia , Transdução de Sinais/fisiologia , Animais , Movimento Celular/fisiologia , Interneurônios/fisiologia , Proteínas Relacionadas a Receptor de LDL/metabolismo , Camundongos , Camundongos Mutantes Neurológicos , Proteínas do Tecido Nervoso/metabolismo , Receptores de LDL/fisiologia
10.
J Neurosci ; 30(33): 10953-66, 2010 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-20720102

RESUMO

Neurons in the developing mammalian neocortex form the cortical plate (CP) in an "inside-out" manner; that is, earlier-born neurons form the deeper layers, whereas later-born neurons migrate past the existing layers and form the more superficial layers. Reelin, a glycoprotein secreted by Cajal-Retzius neurons in the marginal zone (MZ), is crucial for this "inside-out" layering, because the layers are inverted in the Reelin-deficient mouse, reeler (Reln(rl)). Even though more than a decade has passed since the discovery of reelin, the biological effect of Reelin on individual migrating neurons remains unclear. In addition, although the MZ is missing in the reeler cortex, it is unknown whether Reelin directly regulates the development of the cell-body-sparse MZ. To address these issues, we expressed Reelin ectopically in the developing mouse cortex, and the results showed that Reelin caused the leading processes of migrating neurons to assemble in the Reelin-rich region, which in turn induced their cell bodies to form cellular aggregates around Reelin. Interestingly, the ectopic Reelin-rich region became cell-body-sparse and dendrite-rich, resembling the MZ, and the late-born neurons migrated past their predecessors toward the central Reelin-rich region within the aggregates, resulting in a birthdate-dependent "inside-out" alignment even ectopically. Reelin receptors and intracellular adaptor protein Dab1 were found to be necessary for formation of the aggregates. The above findings indicate that Reelin signaling is capable of inducing the formation of the dendrite-rich, cell-body-sparse MZ and a birthdate-dependent "inside-out" alignment of neurons independently of other factors/structures near the MZ.


Assuntos
Moléculas de Adesão Celular Neuronais/metabolismo , Movimento Celular/fisiologia , Proteínas da Matriz Extracelular/metabolismo , Neocórtex/embriologia , Neocórtex/fisiologia , Proteínas do Tecido Nervoso/metabolismo , Neurônios/fisiologia , Serina Endopeptidases/metabolismo , Animais , Moléculas de Adesão Celular Neuronais/genética , Agregação Celular/fisiologia , Linhagem Celular , Dendritos/fisiologia , Proteínas da Matriz Extracelular/genética , Humanos , Camundongos , Camundongos Endogâmicos ICR , Camundongos Transgênicos , Neocórtex/cirurgia , Proteínas do Tecido Nervoso/genética , Serina Endopeptidases/genética , Fatores de Tempo
11.
Dev Biol ; 331(2): 140-51, 2009 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-19409883

RESUMO

The neocortex and the hippocampus comprise several specific layers containing distinct neurons that originate from progenitors at specific development times, under the control of an adequate cell-division patterning mechanism. Although many molecules are known to regulate this cell-division patterning process, its details are not well understood. Here, we show that, in the developing cerebral cortex, the RP58 transcription repressor protein was expressed both in postmitotic glutamatergic projection neurons and in their progenitor cells, but not in GABAergic interneurons. Targeted deletion of the RP58 gene led to dysplasia of the neocortex and of the hippocampus, reduction of the number of mature cortical neurons, and defects of laminar organization, which reflect abnormal neuronal migration within the cortical plate. We demonstrate an impairment of the cell-division patterning during the late embryonic stage and an enhancement of apoptosis of the postmitotic neurons in the RP58-deficient cortex. These results suggest that RP58 controls cell division of progenitor cells and regulates the survival of postmitotic cortical neurons.


Assuntos
Diferenciação Celular/fisiologia , Córtex Cerebral/embriologia , Hipocampo/embriologia , Neurogênese/fisiologia , Neurônios/citologia , Proteínas Repressoras/fisiologia , Sequência de Aminoácidos , Animais , Divisão Celular/fisiologia , Movimento Celular/fisiologia , Córtex Cerebral/citologia , Córtex Cerebral/fisiologia , Hipocampo/citologia , Hipocampo/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Dados de Sequência Molecular , Neurônios/fisiologia , Proteínas Repressoras/genética , Células-Tronco/citologia , Células-Tronco/fisiologia
12.
Biochem Biophys Res Commun ; 372(3): 418-22, 2008 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-18477476

RESUMO

Dynactin is a multi-subunit complex that serves as a critical cofactor of the microtubule motor cytoplasmic dynein. We previously identified dynactin in the nerve growth cone. However, the function of dynactin in the growth cone is still unclear. Here we show that dynactin in the growth cone is required for constant forward movement of the growth cone. Chromophore-assisted laser inactivation (CALI) of dynamitin, a dynactin subunit, within the growth cone markedly decreases the rate of growth cone advance. CALI of dynamitin in vitro dissociates another dynactin subunit, p150(Glued), from dynamitin. These results indicate that dynactin, especially the interaction between dynamitin and p150(Glued), plays an essential role in growth cone advance.


Assuntos
Cones de Crescimento/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Animais , Complexo Dinactina , Lasers , Camundongos , Camundongos Endogâmicos , Proteínas Associadas aos Microtúbulos/efeitos da radiação , Subunidades Proteicas/metabolismo , Subunidades Proteicas/efeitos da radiação
13.
J Biol Chem ; 281(50): 38951-65, 2006 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-17062576

RESUMO

Disabled1 (DAB1) is an intracellular mediator of the Reelin-signaling pathway and essential for correct neuronal positioning during brain development. So far, DAB1 has been considered a cytoplasmic protein. Here, we show that DAB1 is subject to nucleocytoplasmic shuttling. In its steady state, DAB1 is mainly located in the cytoplasm. However, treatment with leptomycine B, a specific inhibitor of the CRM1 (chromosomal region maintenance 1)-RanGTP-dependent nuclear export, resulted in nuclear accumulation of DAB1. By using deletion or substitutional mutants of DAB1 fused with enhanced green fluorescent protein, we have mapped a bipartite nuclear localization signal and two CRM1-dependent nuclear export signals. These targeting signals were functional in both Neuro2a cells and primary cerebral cortical neurons. Using purified recombinant proteins, we have shown that CRM1 binds to DAB1 directly in a RanGTP-dependent manner. We also show that tyrosine phosphorylation of DAB1, which is indispensable for the layer formation of the brain, by Fyn tyrosine kinase or Reelin stimulation did not affect the subcellular localization of DAB1 in vitro. These results suggest that DAB1 is a nucleocytoplasmic shuttling protein and raise the possibility that DAB1 plays a role in the nucleus as well as in the cytoplasm.


Assuntos
Núcleo Celular/metabolismo , Citoplasma/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Primers do DNA , Feminino , Carioferinas/metabolismo , Masculino , Camundongos , Dados de Sequência Molecular , Proteínas do Tecido Nervoso/genética , Receptores Citoplasmáticos e Nucleares/metabolismo
14.
Semin Cell Dev Biol ; 14(3): 169-74, 2003 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-12948351

RESUMO

The complicated mammalian brain structure arises from accurate movements of neurons from their birthplace to their final locations. Detailed observation of this migration process by various methods revealed that neuronal migration is highly motile and that there are different modes of migration. Moreover, mouse mutants or human disorders that disrupt normal migration have provided significant insights into molecular pathways that control the neuronal migration. Although our knowledge is still fragmentary, it is becoming clear that various molecules are participating in this process. In this review, we outline about the cellular and molecular mechanisms of neuronal migration in the cerebral cortex.


Assuntos
Movimento Celular/fisiologia , Neocórtex/citologia , Neocórtex/embriologia , Neurônios/citologia , Neurônios/fisiologia , Animais , Humanos
15.
Brain Res Dev Brain Res ; 143(1): 1-13, 2003 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-12763576

RESUMO

Mouse coxsackie virus and adenovirus receptor (mCAR), which was isolated from the nerve growth cone-enriched fraction of newborn mouse brains, is a member of immunoglobulin-super family, and functions as a homophilic adhesion molecule. We observed the expression of mCAR in embryos to adult tissues by means of immunohistochemical analysis with a peptide antibody. mCAR expression was first detected in the embryonic ectoderm in the uterus on embryonic day 6.5 (E6.5). Then it was strongly expressed in the neuroepithelium of the neural tube, the developing brain and the spinal cord from E8.5 to postnatal day 7 (P7), in the cranial motor nerves from E9.5 to E11.5, and in the optic nerve from E13.5 to P7, which agrees with periods of their respective morphogenetic peaks. This expression of mCAR decreased postnatally and was absent in adult tissues. We found that mCAR occurred in a few proliferating cells of the hippocampal dentate gyrus, the subventricular zone (SVZ) of the lateral ventricles, and the rostral migratory stream (RMS) over P21. These observations demonstrate that mCAR was expressed characteristically in the immature neuroepithelium including progenitor cells or radial cells derived from the neural tube and in immature cells in a selected germinal zone of the mature brain. Based on our findings, we propose that mCAR is involved in migration and fasciculation during a restricted period as an adhesion molecule.


Assuntos
Encéfalo/metabolismo , Embrião de Mamíferos/metabolismo , Desenvolvimento Embrionário e Fetal , Regulação da Expressão Gênica no Desenvolvimento , Proteínas do Tecido Nervoso , Receptores Virais/metabolismo , Animais , Animais Recém-Nascidos , Encéfalo/embriologia , Encéfalo/crescimento & desenvolvimento , Proteína de Membrana Semelhante a Receptor de Coxsackie e Adenovirus , Técnicas de Cultura , Diencéfalo/anatomia & histologia , Diencéfalo/embriologia , Diencéfalo/crescimento & desenvolvimento , Diencéfalo/metabolismo , Ectoderma/metabolismo , Epitélio/embriologia , Epitélio/crescimento & desenvolvimento , Epitélio/metabolismo , Olho/anatomia & histologia , Olho/embriologia , Olho/crescimento & desenvolvimento , Olho/metabolismo , Feminino , Proteína Glial Fibrilar Ácida/metabolismo , Hipocampo/citologia , Hipocampo/fisiologia , Imuno-Histoquímica/métodos , Proteínas de Filamentos Intermediários/metabolismo , Camundongos , Mucosa Nasal/metabolismo , Nestina , Proteínas de Neurofilamentos/metabolismo , Nariz/anatomia & histologia , Nariz/embriologia , Nariz/crescimento & desenvolvimento , Fragmentos de Peptídeos/imunologia , Fragmentos de Peptídeos/metabolismo , Gravidez , Antígeno Nuclear de Célula em Proliferação/metabolismo , Medula Espinal/anatomia & histologia , Medula Espinal/embriologia , Medula Espinal/crescimento & desenvolvimento , Medula Espinal/metabolismo , Telencéfalo/anatomia & histologia , Telencéfalo/embriologia , Telencéfalo/crescimento & desenvolvimento , Telencéfalo/metabolismo , Tubulina (Proteína)/metabolismo
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