Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 39
Filtrar
Filtros adicionais











País/Região como assunto
Intervalo de ano
1.
J Comp Neurol ; 527(10): 1577-1597, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30636008

RESUMO

During development of the mammalian cerebral neocortex, postmitotic excitatory neurons migrate toward the outermost region of the neocortex. We previously reported that this outermost region is composed of densely packed relatively immature neurons; we named this region, which is observed during the late stage of mouse neocortical development, the "primitive cortical zone (PCZ)." Here, we report that postmigratory immature neurons spend about 1-1.5 days in the PCZ. An electron microscopic analysis showed that the neurons in the PCZ tend to be in direct contact with each other, mostly in a radial direction, forming "primitive neuronal clusters" with a height of 3-7 cells and a width of 1-2 cells. A time-course analysis of fluorescently labeled neurons revealed that the neurons took their positions within the primitive clusters in an inside-out manner. The neurons initially participated in the superficial part of the clusters, gradually shifted their relative positions downward, and then left the clusters at the bottom of this structure. GABAergic inhibitory interneurons were also found within the primitive clusters in the developing mouse neocortex, suggesting that some clusters are composed of both excitatory neurons and inhibitory interneurons. Similar clusters were also observed in the outermost region of embryonic day (E) 78 cynomolgus monkey occipital cortex and 23 gestational week (GW) human neocortices. In the primate neocortices, including human, the presumptive primitive clusters seemed to expand in the radial direction more than that observed in mice, which might contribute to the functional integrity of the primate neocortex.

2.
J Neurosci ; 2018 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-30504273

RESUMO

The actin cytoskeleton is crucial for neuronal migration in the mammalian developing cerebral cortex. The adaptor protein Drebrin-like (Dbnl) plays important roles in reorganization of the actin cytoskeleton, dendrite formation, and endocytosis by interacting with F-actin, cobl, and dynamin. While Dbnl is known to be expressed in the brain, the functions of this molecule during brain development are largely unknown. In this study, to examine the roles of Dbnl in the developing cerebral cortex, we conducted experiments using of both sexes mice with knockdown of Dbnl, effected by in utero electroporation, in the migrating neurons of the embryonic cortex. Time-lapse imaging of the Dbnl-knockdown neurons revealed that the presence of Dbnl is a prerequisite for appropriate formation of processes in the multipolar neurons in the multipolar cell accumulation zone (MAZ) or the deep part of the subventricular zone (SVZ), and for neuronal polarization and entry into the cortical plate. We found that Dbnl knockdown decreased the amount of N-cadherin protein expressed on the plasma membrane of the cortical neurons. The defect in neuronal migration caused by Dbnl knockdown was rescued by moderate overexpression of N-cadherin and αN-catenin or by transfection of the phospho-mimic form (Y337E, Y347E), but not the phospho-resistant form (Y337F, Y347F), of Dbnl. These results suggest that Dbnl controls neuronal migration, neuronal multipolar morphology, and cell polarity in the developing cerebral cortex via regulating N-cadherin expression.SIGNIFICANCE STATEMENTDisruption of neuronal migration can cause neuronal disorders such as lissencephaly and subcortical band heterotopia. During cerebral cortical development, the actin cytoskeleton plays a key role in neuronal migration, however, the mechanisms of regulation of neuronal migration by the actin cytoskeleton still remain unclear. Herein, we report that the novel protein Dbnl, an actin-binding protein, controls multiple events during neuronal migration in the developing mouse cerebral cortex. We also showed that this regulation is mediated by phosphorylation of Dbnl at tyrosine residues 337 and 347 and αN-catenin/N-cadherin, suggesting that the Dbnl-αN-catenin/N-cadherin pathway is important for neuronal migration in the developing cortex.

3.
Cereb Cortex ; 28(1): 223-235, 2018 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-27909010

RESUMO

Neuronal migration contributes to the establishment of mammalian brain. The extracellular protein Reelin sends signals to various downstream molecules by binding to its receptors, the apolipoprotein E receptor 2 (ApoER2) and very low-density lipoprotein receptor and exerts essential roles in the neuronal migration and formation of the layered neocortex. However, the cellular and molecular functions of Reelin signaling in the cortical development are not yet fully understood. Here, to gain insight into the role of Reelin signaling during cortical development, we examined the migratory behavior of Apoer2-deficient neurons in the developing brain. Stage-specific labeling of newborn neurons revealed that the neurons ectopically invaded the marginal zone (MZ) and that neuronal migration of both early- and late-born neurons was disrupted in the intermediate zone (IZ) in the Apoer2 KO mice. Rescue experiments showed that ApoER2 functions both in cell-autonomous and noncell-autonomous manners, that Rap1, integrin, and Akt are involved in the termination of migration beneath the MZ, and that Akt also controls neuronal migration in the IZ downstream of ApoER2. These data indicate that ApoER2 controls multiple processes in neuronal migration, including the early stage of radial migration and termination of migration beneath the MZ in the developing neocortex.


Assuntos
Movimento Celular/fisiologia , Córtex Cerebral/crescimento & desenvolvimento , Córtex Cerebral/metabolismo , Proteínas Relacionadas a Receptor de LDL/metabolismo , Neurônios/metabolismo , Animais , Região CA1 Hipocampal/citologia , Região CA1 Hipocampal/crescimento & desenvolvimento , Região CA1 Hipocampal/metabolismo , Córtex Cerebral/citologia , Proteoglicanas de Sulfatos de Condroitina/metabolismo , Integrinas/metabolismo , Proteínas Relacionadas a Receptor de LDL/genética , Camundongos Knockout , Proteínas Associadas aos Microtúbulos/metabolismo , Neurônios/citologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas rap1 de Ligação ao GTP/metabolismo
4.
PLoS One ; 12(8): e0183497, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28820910

RESUMO

The basic helix-loop-helix (bHLH) transcription factors exert multiple functions in mammalian cerebral cortex development. The aryl hydrocarbon receptor (AhR), a member of the bHLH-Per-Arnt-Sim subfamily, is a ligand-activated transcription factor reported to regulate nervous system development in both invertebrates and vertebrates, but the functions that AhR signaling pathway may have for mammalian cerebral cortex development remains elusive. Although the endogenous ligand involved in brain developmental process has not been identified, the environmental pollutant dioxin potently binds AhR and induces abnormalities in higher brain function of laboratory animals. Thus, we studied how activation of AhR signaling influences cortical development in mice. To this end, we produced mice expressing either constitutively active-AhR (CA-AhR), which has the capacity for ligand-independent activation of downstream genes, or AhR, which requires its ligands for activation. In brief, CA-AhR-expressing plasmid and AhR-expressing plasmid were each transfected into neural stems cells in the developing cerebrum by in utero electroporation on embryonic day 14.5. On postnatal day 14, mice transfected in utero with CA-AhR, but not those transfected with AhR, exhibited drastically reduced dendritic arborization of layer II/III pyramidal neurons and impaired neuronal positioning in the developing somatosensory cortex. The effects of CA-AhR were observed for dendrite development but not for the commissural fiber projection, suggesting a preferential influence on dendrites. The present results indicate that over-activation of AhR perturbs neuronal migration and morphological development in mammalian cortex, supporting previous observations of impaired dendritic structure, cortical dysgenesis, and behavioral abnormalities following perinatal dioxin exposure.


Assuntos
Dendritos , Células Piramidais/metabolismo , Receptores de Hidrocarboneto Arílico/metabolismo , Transdução de Sinais , Animais , Camundongos , Camundongos Endogâmicos C57BL
5.
JCI Insight ; 2(10)2017 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-28515367

RESUMO

Many extremely preterm infants (born before 28 gestational weeks [GWs]) develop cognitive impairment in later life, although the underlying pathogenesis is not yet completely understood. Our examinations of the developing human neocortex confirmed that neuronal migration continues beyond 23 GWs, the gestational week at which extremely preterm infants have live births. We observed larger numbers of ectopic neurons in the white matter of the neocortex in human extremely preterm infants with brain injury and hypothesized that altered neuronal migration may be associated with cognitive impairment in later life. To confirm whether preterm brain injury affects neuronal migration, we produced brain damage in mouse embryos by occluding the maternal uterine arteries. The mice showed delayed neuronal migration, ectopic neurons in the white matter, altered neuronal alignment, and abnormal corticocortical axonal wiring. Similar to human extremely preterm infants with brain injury, the surviving mice exhibited cognitive deficits. Activation of the affected medial prefrontal cortices of the surviving mice improved working memory deficits, indicating that decreased neuronal activity caused the cognitive deficits. These findings suggest that altered neuronal migration altered by brain injury might contribute to the subsequent development of cognitive impairment in extremely preterm infants.

6.
Proc Natl Acad Sci U S A ; 114(8): 2048-2053, 2017 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-28174271

RESUMO

Reelin is an essential glycoprotein for the establishment of the highly organized six-layered structure of neurons of the mammalian neocortex. Although the role of Reelin in the control of neuronal migration has been extensively studied at the molecular level, the mechanisms underlying Reelin-dependent neuronal layer organization are not yet fully understood. In this study, we directly showed that Reelin promotes adhesion among dissociated neocortical neurons in culture. The Reelin-mediated neuronal aggregation occurs in an N-cadherin-dependent manner, both in vivo and in vitro. Unexpectedly, however, in a rotation culture of dissociated neocortical cells that gradually reaggregated over time, we found that it was the neural progenitor cells [radial glial cells (RGCs)], rather than the neurons, that tended to form clusters in the presence of Reelin. Mathematical modeling suggested that this clustering of RGCs could be recapitulated if the Reelin-dependent promotion of neuronal adhesion were to occur only transiently. Thus, we directly measured the adhesive force between neurons and N-cadherin by atomic force microscopy, and found that Reelin indeed enhanced the adhesiveness of neurons to N-cadherin; this enhanced adhesiveness began to be observed at 30 min after Reelin stimulation, but declined by 3 h. These results suggest that Reelin transiently (and not persistently) promotes N-cadherin-mediated neuronal aggregation. When N-cadherin and stabilized ß-catenin were overexpressed in the migrating neurons, the transfected neurons were abnormally distributed in the superficial region of the neocortex, suggesting that appropriate regulation of N-cadherin-mediated adhesion is important for correct positioning of the neurons during neocortical development.


Assuntos
Caderinas/metabolismo , Moléculas de Adesão Celular Neuronais/fisiologia , Adesão Celular/fisiologia , Proteínas da Matriz Extracelular/fisiologia , Neocórtex/embriologia , Proteínas do Tecido Nervoso/fisiologia , Neurônios/fisiologia , Serina Endopeptidases/fisiologia , beta Catenina/metabolismo , Animais , Caderinas/genética , Moléculas de Adesão Celular Neuronais/genética , Movimento Celular , Células Cultivadas , Células Ependimogliais , Proteínas da Matriz Extracelular/genética , Feminino , Técnicas de Silenciamento de Genes , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Endogâmicos ICR , Camundongos Transgênicos , Microscopia de Força Atômica , Proteínas do Tecido Nervoso/genética , Neurogênese , Neurônios/ultraestrutura , Serina Endopeptidases/genética , Imagem Individual de Molécula
7.
J Toxicol Sci ; 42(1): 25-30, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28070106

RESUMO

The aryl hydrocarbon receptor (AhR) avidly binds dioxin, a ubiquitous environmental contaminant. Disruption of downstream AhR signaling has been reported to alter neuronal development, and rodent offspring exposed to dioxin during gestation and lactation showed abnormalities in learning and memory, emotion, and social behavior. However, the mechanism behind the disrupted AhR signaling and developmental neurotoxicity induced by xenobiotic ligands remains elusive. Therefore, we studied how excessive AhR activation affects neuronal migration in the hippocampal CA1 region of the developing mouse brain. We transfected constitutively active (CA)-AhR, AhR, or control vector plasmids into neurons via in utero electroporation on gestational day 14 and analyzed neuronal positioning in the hippocampal CA1 region of offspring on postnatal day 14. CA-AhR transfection affected neuronal positioning, whereas no change was observed in AhR-transfected or control hippocampus. These results suggest that constitutively activated AhR signaling disrupts neuronal migration during hippocampal development. Further studies are needed to investigate whether such developmental disruption in the hippocampus leads to the abnormal cognition and behavior of rodent offspring upon maternal exposure to AhR xenobiotic ligands.


Assuntos
Região CA1 Hipocampal/fisiologia , Neurônios/fisiologia , Receptores de Hidrocarboneto Arílico/genética , Animais , Região CA1 Hipocampal/embriologia , Movimento Celular , Eletroporação , Embrião de Mamíferos , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Gravidez , Transdução de Sinais
8.
Front Cell Neurosci ; 10: 229, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27803648

RESUMO

Proper neuronal migration and laminar formation during corticogenesis is essential for normal brain function. Disruption of these developmental processes is thought to be involved in the pathogenesis of some neuropsychiatric conditions. Especially, Reelin, a glycoprotein mainly secreted by the Cajal-Retzius cells and a subpopulation of GABAergic interneurons, has been shown to play a critical role, both during embryonic and postnatal periods. Indeed, animal studies have clearly revealed that Reelin is an essential molecule for proper migration of cortical neurons and finally regulates the cell positioning in the cortex during embryonic and early postnatal stages; by contrast, Reelin signaling is closely involved in synaptic function in adulthood. In humans, genetic studies have shown that the reelin gene (RELN) is associated with a number of psychiatric diseases, including Schizophrenia (SZ), bipolar disorder (BP) and autistic spectrum disorder. Indeed, Reln haploinsufficiency has been shown to cause cognitive impairment in rodents, suggesting the expression level of the Reelin protein is closely related to the higher brain functions. However, the molecular abnormalities in the Reelin pathway involved in the pathogenesis of psychiatric disorders are not yet fully understood. In this article, we review the current progress in the understanding of the Reelin functions that could be related to the pathogenesis of psychiatric disorders. Furthermore, we discuss the basis for selecting Reelin and molecules in its downstream signaling pathway as potential therapeutic targets for psychiatric illnesses.

10.
Mol Neuropsychiatry ; 2(1): 20-27, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27525255

RESUMO

DISC1 is a multifunctional, intracellular scaffold protein. At the cellular level, DISC1 plays a pivotal role in neural progenitor proliferation, migration, and synaptic maturation. Perturbation of the biological pathways involving DISC1 is known to lead to behavioral changes in rodents, which supports a clinical report of a Scottish pedigree in which the majority of family members with disruption of the DISC1 gene manifest depression, schizophrenia, and related mental conditions. The discrepancy of modest evidence in genetics but strong biological support for the role of DISC1 in mental conditions suggests a working hypothesis that regulation of DISC1 at the protein level, such as posttranslational modification, may play a role in the pathology of mental conditions. In this study, we report the SUMOylation of DISC1. This posttranslational modification occurs on lysine residues where small ubiquitin-related modifier (SUMO) and its homologs are conjugated to a large number of cellular proteins, which in turn regulates their subcellular distribution and protein stability. By using in silico, biochemical, and cell biological approaches, we now demonstrate that human DISC1 is SUMOylated at one specific lysine 643 (K643). We also show that this residue is crucial for proper neural progenitor proliferation in the developing cortex.

11.
Artigo em Inglês | MEDLINE | ID: mdl-26869994

RESUMO

Bisphenol A (BPA) has been known to have endocrine-disrupting activity to induce reproductive and behavioral abnormalities in offspring of laboratory animal species. However, morphological basis of this abnormality during brain development is largely unknown. Cerebral cortex plays a crucial role in higher brain function, and its precisely laminated structure is formed by neuronal migration. In the present study, transfecting a plasmid (pCAG-mCherry) by in utero electroporation (IUE), we visualized developing neurons and investigated the possible effects of in utero BPA exposure on neuronal migration. Pregnant mice were exposed to BPA by osmotic pump at estimated daily doses of 0, 40 (BPA-40), or 400 (BPA-400) µg/kg from embryonic day 14.5 (E14.5) to E18.5. IUE was performed at E14.5 and neuronal migration was analyzed at E18.5. Compared with the control group, neuronal migration in the cortical plate was significantly decreased in the BPA-40 group; however, there was no significant difference in the BPA-400 group. Among several neuronal migration-related genes and cortical layer-specific genes, TrkB in the BPA-400 group was found significantly upregulated. In conclusion, in utero exposure to low BPA dose was found to disrupt neuronal migration in the cerebral cortex in a dose-specific manner.

12.
Schizophr Res ; 171(1-3): 92-6, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26805409

RESUMO

The resilience levels between patients with schizophrenia residing in a rural island and a metropolitan area in Tokyo, Japan, was compared and the factors associated with resilience were explored. The Resilience Scale (RS) and EuroQol were assessed, together with biological markers and multiple demographic variables. No significant difference was found in the RS scores between the two groups (40 subjects each). However, longer duration of illness and higher EuroQol score were significantly associated with a greater RS score, which indicates that potentially successful adaptation and subjective perspectives appear more pertinent than the degree of urbanicity in determining resilience levels.


Assuntos
Resiliência Psicológica , Esquizofrenia , Psicologia do Esquizofrênico , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Feminino , Humanos , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Escalas de Graduação Psiquiátrica , Qualidade de Vida/psicologia , Estudos Retrospectivos , População Rural , Esquizofrenia/epidemiologia , Inquéritos e Questionários , População Urbana , Adulto Jovem
13.
Neurotoxicol Teratol ; 52(Pt A): 42-50, 2015 Nov-Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26526904

RESUMO

Increased prevalence of mental disorders cannot be solely attributed to genetic factors and is considered at least partly attributable to chemical exposure. Among various environmental chemicals, in utero and lactational dioxin exposure has been extensively studied and is known to induce higher brain function abnormalities in both humans and laboratory animals. However, how the perinatal dioxin exposure affects neuromorphological alterations has remained largely unknown. Therefore, in this study, we initially studied whether and how the over-expression of aryl hydrocarbon receptor (AhR), a dioxin receptor, would affect the dendritic growth in the hippocampus of the developing brain. Transfecting a constitutively active AhR plasmid into the hippocampus via in utero electroporation on gestational day (GD) 14 induced abnormal dendritic branch growth. Further, we observed that 14-day-old mice born to dams administered with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; dose: 0, 0.6, or 3.0 µg/kg) on GD 12.5 exhibited disrupted dendritic branch growth in both the hippocampus and amygdala. Finally, we observed that 16-month-old mice born to dams exposed to perinatal TCDD as described above exhibited significantly reduced spine densities. These results indicated that abnormal micromorphology observed in the developing brain may persist until adulthood and may induce abnormal higher brain function later in life.


Assuntos
Dendritos/efeitos dos fármacos , Dendritos/patologia , Poluentes Ambientais/toxicidade , Hipocampo/efeitos dos fármacos , Hipocampo/crescimento & desenvolvimento , Hipocampo/patologia , Dibenzodioxinas Policloradas/toxicidade , Receptores de Hidrocarboneto Arílico/metabolismo , Tonsila do Cerebelo/efeitos dos fármacos , Tonsila do Cerebelo/crescimento & desenvolvimento , Tonsila do Cerebelo/patologia , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/crescimento & desenvolvimento , Encéfalo/patologia , Espinhas Dendríticas/efeitos dos fármacos , Espinhas Dendríticas/patologia , Relação Dose-Resposta a Droga , Poluentes Ambientais/análise , Feminino , Hipocampo/metabolismo , Masculino , Exposição Materna , Camundongos , Camundongos Endogâmicos C57BL , Dibenzodioxinas Policloradas/análise , Células Piramidais/efeitos dos fármacos , Células Piramidais/metabolismo , Células Piramidais/patologia
14.
J Neurosci ; 35(36): 12432-45, 2015 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-26354912

RESUMO

Neuronal heterotopia refers to brain malformations resulting from deficits of neuronal migration. Individuals with heterotopias show a high incidence of neurological deficits, such as epilepsy. More recently, it has come to be recognized that focal heterotopias may also show a range of psychiatric problems, including cognitive and behavioral impairments. However, because focal heterotopias are not always located in the brain areas responsible for the symptoms, the causal relationship between the symptoms and heterotopias remains elusive. In this study, we showed that mice with focal heterotopias in the somatosensory cortex generated by in utero electroporation exhibited spatial working memory deficit and low competitive dominance behavior, which have been shown to be closely associated with the activity of the medial prefrontal cortex (mPFC) in rodents. Analysis of the mPFC activity revealed that the immediate-early gene expression was decreased and the local field potentials of the mPFC were altered in the mice with heterotopias compared with the control mice. Moreover, activation of these ectopic and overlying sister neurons using the DREADD (designer receptor exclusively activated by designer drug) system improved the working memory deficits. These findings suggest that cortical regions containing focal heterotopias can affect distant brain regions and give rise to behavioral abnormalities. Significance statement: Recent studies reported that patients with heterotopias have a variety of clinical symptoms, such as cognitive disturbance, psychiatric symptoms, and autistic behavior. However, the causal relationship between the symptoms and heterotopias remains elusive. Here we showed that mice with focal heterotopias in the somatosensory cortex generated by in utero electroporation exhibited behavioral deficits that have been shown to be associated with the mPFC activity in rodents. The existence of heterotopias indeed altered the neural activities of the mPFC, and direct manipulation of the neural activity of the ectopic neurons and their sister neurons in the overlying cortex improved the behavioral deficit. Thus, our results indicate that focal heterotopias could affect the activities of distant brain areas and cause behavioral abnormalities.


Assuntos
Malformações do Desenvolvimento Cortical/fisiopatologia , Transtornos Mentais/fisiopatologia , Córtex Pré-Frontal/fisiopatologia , Córtex Somatossensorial/fisiopatologia , Animais , Genes Precoces , Aprendizagem em Labirinto , Memória , Camundongos , Córtex Pré-Frontal/anormalidades , Córtex Pré-Frontal/metabolismo , Comportamento Social , Córtex Somatossensorial/anormalidades , Córtex Somatossensorial/metabolismo
15.
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
16.
Front Neurosci ; 9: 135, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25964735

RESUMO

A fine structure of the hippocampus is required for proper functions, and disruption of this formation by neuronal migration defects during development may play a role in some psychiatric illnesses. During hippocampal development in rodents, pyramidal neurons in the Ammon's horn are mostly generated in the ventricular zone (VZ), spent as multipolar cells just above the VZ, and then migrate radially toward the pial surface, ultimately settling into the hippocampal plate. Although this process is similar to that of neocortical projection neurons, these are not identical. In addition to numerous histological studies, the development of novel techniques gives a clear picture of the cellular dynamics of hippocampal neurons, as well as neocortical neurons. In this article, we provide an overview of the cellular mechanisms of rodent hippocampal neuronal migration including those of dentate granule cells, especially focusing on the differences of migration modes between hippocampal neurons and neocortical neurons. The unique migration mode of hippocampal pyramidal neurons might enable clonally related cells in the Ammon's horn to distribute in a horizontal fashion.

17.
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
18.
Neurosci Res ; 96: 30-6, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25573715

RESUMO

Reelin has recently attracted attention because of its connection to several neuropsychiatric diseases. We previously reported the finding that prior transplantation of GABAergic neuron precursor cells into the medial prefrontal cortex (mPFC) of mice significantly prevented the induction of cognitive and sensory-motor gating deficits induced by phencyclidine (PCP). The majority of the precursor cells transplanted into the mPFC of the recipient mice differentiated into members of a somatostatin/Reelin-expressing class of GABAergic interneurons. These findings raised the possibility that Reelin secreted by the transplanted cells plays an important role in preventing the deficits induced by PCP. In this study, we investigated whether Reelin itself has a preventive effect on PCP-induced behavioral phenotypes by injecting conditioned medium containing Reelin into the lateral ventricle of the brains of 6- to 7-week-old male mice before administrating PCP. Behavioral analyses showed that the prior Reelin injection had a preventive effect against induction of the cognitive and sensory-motor gating deficits associated with PCP. Moreover, one of the types of Reelin receptor was found to be expressed by neurons in the mPFC. The results of this study point to the Reelin signaling pathway as a candidate target for the pharmacologic treatment of neuropsychiatric diseases.


Assuntos
Moléculas de Adesão Celular Neuronais/administração & dosagem , Moléculas de Adesão Celular Neuronais/metabolismo , Transtornos Cognitivos/prevenção & controle , Proteínas da Matriz Extracelular/administração & dosagem , Proteínas da Matriz Extracelular/metabolismo , Proteínas do Tecido Nervoso/administração & dosagem , Proteínas do Tecido Nervoso/metabolismo , Filtro Sensorial/efeitos dos fármacos , Serina Endopeptidases/administração & dosagem , Serina Endopeptidases/metabolismo , Animais , Transtornos Cognitivos/induzido quimicamente , Neurônios GABAérgicos , Infusões Intraventriculares , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos ICR , Neurônios/metabolismo , Fenciclidina/toxicidade , Córtex Pré-Frontal/metabolismo , Receptores de LDL/metabolismo
19.
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
20.
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
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA