The Experts below are selected from a list of 6597 Experts worldwide ranked by ideXlab platform
Mitsuharu Hattori - One of the best experts on this subject based on the ideXlab platform.
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Regulation of Reelin functions by specific proteolytic processing in the brain.
Journal of biochemistry, 2021Co-Authors: Mitsuharu Hattori, Takao KohnoAbstract:The secreted glycoprotein Reelin plays important roles in both brain development and function. During development, Reelin regulates neuronal migration and dendrite development. In the mature brain, the glycoprotein is involved in synaptogenesis and synaptic plasticity. It has been suggested that Reelin loss or decreased function contributes to the onset and/or deterioration of neuropsychiatric diseases, including schizophrenia and Alzheimer's disease. While the molecular mechanisms underpinning Reelin function remain unclear, recent studies have suggested that the specific proteolytic cleavage of Reelin may play central roles in the embryonic and postnatal brain. In this review, we focus on Reelin proteolytic processing and review its potential physiological roles.
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Physiological significance of proteolytic processing of Reelin revealed by cleavage-resistant Reelin knock-in mice.
Scientific reports, 2020Co-Authors: Eisuke Okugawa, Takao Kohno, Himari Ogino, Tomofumi Shigenobu, Yuko Yamakage, Hitomi Tsuiji, Hisashi Oishi, Mitsuharu HattoriAbstract:Reelin is a secreted protein that plays versatile roles in neuronal development and function. The strength of Reelin signaling is regulated by proteolytic processing, but its importance in vivo is not yet fully understood. Here, we generated Reelin knock-in (PA-DV KI) mice in which the key cleavage site of Reelin was abolished by mutation. As expected, the cleavage of Reelin was severely abrogated in the cerebral cortex and hippocampus of PA-DV KI mice. The amount of Dab1, whose degradation is induced by Reelin signaling, decreased in these tissues, indicating that the signaling strength of Reelin was augmented. The brains of PA-DV KI mice were largely structurally normal, but unexpectedly, the hippocampal layer was disturbed. This phenotype was ameliorated in hemizygote PA-DV KI mice, indicating that excess Reelin signaling is detrimental to hippocampal layer formation. The neuronal dendrites of PA-DV KI mice had more branches and were elongated compared to wild-type mice. These results present the first direct evidence of the physiological importance of Reelin cleavage.
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Physiological significance of proteolytic processing of Reelin revealed by cleavage-resistant Reelin knock-in mice
2020Co-Authors: Eisuke Okugawa, Takao Kohno, Himari Ogino, Tomofumi Shigenobu, Yuko Yamakage, Hitomi Tsuiji, Hisashi Oishi, Mitsuharu HattoriAbstract:Reelin is a secreted protein that plays versatile roles in neuronal development and function, and hypoactivity of Reelin is implicated in many neuropsychiatric disorders. The strength of Reelin signaling is regulated by proteolytic processing, but its importance in vivo is not yet fully understood. Here, we generated Reelin knock-in (PA-DV KI) mice in which the key cleavage site of Reelin was abolished by mutation. As expected, the cleavage of Reelin was severely abrogated in the cerebral cortex and hippocampus of PA-DV KI mice. The amount of Dab1, whose degradation is induced by Reelin signaling, decreased in these tissues, indicating that the signaling strength of Reelin was augmented. The brains of PA-DV KI mice were largely structurally normal, but unexpectedly, the hippocampal layer was disturbed. This phenotype was ameliorated in hemizygote PA-DV KI mice, indicating that excess Reelin signaling is detrimental to hippocampal layer formation. The neuronal dendrites of PA-DV KI mice had more branches and were elongated compared to wild-type mice. These results present the first direct evidence of the physiological importance of Reelin cleavage and suggest that inhibition of Reelin cleavage would counteract neuropsychiatric disorders without causing severe systemic side effects.
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Assay for Reelin-Cleaving Activity of ADAMTS and Detection of Reelin and Its Fragments in the Brain.
Methods in molecular biology (Clifton N.J.), 2019Co-Authors: Himari Ogino, Takao Kohno, Yuko Yamakage, Mihoshi B Yamashita, Mitsuharu HattoriAbstract:Proteolytic cleavage of the secreted signaling protein Reelin has been suggested to play causative roles in many neuropsychiatric and neurodegenerative disorders. Therefore, characterization of the proteolytic activity against Reelin is important not only for understanding how the brain works but also for the development of novel therapy for these disorders. Notably, ADAMTS family proteases are the primary suspects of Reelin-cleaving proteases under many, though not all, circumstances. Here we describe how to measure the Reelin-cleaving activity of ADAMTS (or of any other protease that may cleave Reelin), how to purify the Reelin-cleaving protease ADAMTS-3 from the culture supernatant of cortical neurons, and how to detect endogenous Reelin protein and its fragments in the brain.
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Differential binding of anti-Reelin monoclonal antibodies reveals the characteristics of Reelin protein under various conditions.
Biochemical and biophysical research communications, 2019Co-Authors: Keisuke Ishii, Takao Kohno, Mitsuharu HattoriAbstract:Abstract Reelin is a large secreted protein that is essential for the development and function of the central nervous system. Dimerization and/or oligomerization is required for its biological activity, but the underlying mechanism is not fully understood. There are several widely used anti-Reelin antibodies and we noticed that their reactivity to monomeric or dimeric Reelin protein is different. We also found that their reactivity to Reelin in the solution or in fixed brain tissues also differs. Our results provide the information regarding how the N-terminal region of Reelin folds and contributes to the formation of higher order structure. We also provide a caveat that appropriate use of anti-Reelin antibody is necessary for quantitative analyses.
Michael Frotscher - One of the best experts on this subject based on the ideXlab platform.
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proteolytic cleavage of transmembrane cell adhesion molecule l1 by extracellular matrix molecule Reelin is important for mouse brain development
Scientific Reports, 2017Co-Authors: David Lutz, Ahmed Sharaf, Dagmar Drexler, Hardeep Kataria, Gerrit Wolterseisfeld, Bianka Brunne, Ralf Kleene, Gabriele Loers, Michael Frotscher, Melitta SchachnerAbstract:The cell adhesion molecule L1 and the extracellular matrix protein Reelin play crucial roles in the developing nervous system. Reelin is known to activate signalling cascades regulating neuronal migration by binding to lipoprotein receptors. However, the interaction of Reelin with adhesion molecules, such as L1, has remained poorly explored. Here, we report that full-length Reelin and its N-terminal fragments N-R2 and N-R6 bind to L1 and that full-length Reelin and its N-terminal fragment N-R6 proteolytically cleave L1 to generate an L1 fragment with a molecular mass of 80 kDa (L1-80). Expression of N-R6 and generation of L1-80 coincide in time at early developmental stages of the cerebral cortex. Reelin-mediated generation of L1-80 is involved in neurite outgrowth and in stimulation of migration of cultured cortical and cerebellar neurons. Morphological abnormalities in layer formation of the cerebral cortex of L1-deficient mice partially overlap with those of Reelin-deficient reeler mice. In utero electroporation of L1-80 into reeler embryos normalised the migration of cortical neurons in reeler embryos. The combined results indicate that the direct interaction between L1 and Reelin as well as the Reelin-mediated generation of L1-80 contribute to brain development at early developmental stages.
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Go or Stop? Divergent Roles of Reelin in Radial Neuronal Migration
The Neuroscientist : a review journal bringing neurobiology neurology and psychiatry, 2010Co-Authors: Shanting Zhao, Michael FrotscherAbstract:Neuronal migration is an essential step of brain development and is controlled by a variety of cellular proteins and extracellular matrix molecules. Reelin, an extracellular matrix protein, is required for neuronal migration. Over the past 10 years, the Reelin signaling cascade has been studied intensively. However, the role of Reelin in neuronal migration has remained unclear. Different Reelin fragments and different Reelin receptors suggest multiple functions of Reelin. In this review, the authors focus on Reelin effects on the actin cytoskeleton of migrating neurons.
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Role for Reelin in stabilizing cortical architecture.
Trends in neurosciences, 2010Co-Authors: Michael FrotscherAbstract:Reelin controls the migration of neurons and layer formation during brain development. However, recent studies have shown that disrupting Reelin function in the adult hippocampus induces repositioning of fully differentiated neurons, suggesting a stabilizing effect of Reelin on mature neuronal circuitry. Indeed, Reelin was recently found to stabilize the actin cytoskeleton by inducing cofilin phosphorylation. When unphosphorylated, cofilin acts as an actin-depolymerizing protein that promotes the disassembly of F-actin. Here, a novel hypothesis is proposed whereby decreased Reelin expression in the mature brain causes destabilization of neurons and their processes, leading to aberrant plasticity and aberrant wiring of brain circuitry. This has implications for brain disorders, such as epilepsy and schizophrenia, in which deficiencies in Reelin expression occur.
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Emerging topics in Reelin function
The European journal of neuroscience, 2010Co-Authors: Eckart Forster, Michael Frotscher, Joachim Herz, Hans H. Bock, Xuejun Chai, Shanting ZhaoAbstract:Reelin signalling in the early developing cortex regulates radial migration of cortical neurons. Later in development, Reelin promotes maturation of dendrites and dendritic spines. Finally, in the mature brain, it is involved in modulating synaptic function. In recent years, efforts to identify downstream signalling events induced by binding of Reelin to lipoprotein receptors led to the characterization of novel components of the Reelin signalling cascade. In the present review, we first address distinct functions of the Reelin receptors Apoer2 and Vldlr in cortical layer formation, followed by a discussion on the recently identified downstream effector molecule n-cofilin, involved in regulating actin cytoskeletal dynamics required for coordinated neuronal migration. Next, we discuss possible functions of the recently identified Reelin-Notch signalling crosstalk, and new aspects of the role of Reelin in the formation of the dentate radial glial scaffold. Finally, progress in characterizing the function of Reelin in modulating synaptic function in the adult brain is summarized. The present review has been inspired by a session entitled 'Functions of Reelin in the developing and adult hippocampus', held at the Spring Hippocampal Research Conference in Verona/Italy, June 2009.
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Reelin deficiency causes granule cell dispersion in epilepsy.
Experimental brain research, 2009Co-Authors: Carola A. Haas, Michael FrotscherAbstract:Cortical migration defects are often associated with epilepsy. In mesial temporal lobe epilepsy (MTLE), granule cell dispersion (GCD), a migration defect of dentate granule cells, is frequently observed. Little is known how GCD develops and to which extent it contributes to the development of seizure activity. Since the Reelin-deficient reeler mouse mutant shows a similar migration defect of dentate cells, we performed a series of studies investigating whether Reelin deficiency is involved in GCD development. We show that in MTLE patients and in a mouse model of MTLE, the development of GCD correlates with a loss of the extracellular matrix protein Reelin. In addition, we present evidence that GCD occurs in the absence of neurogenesis, thus representing a displacement of mature neurons due to a Reelin deficiency. Accordingly, antibody blockade of Reelin function in naive, adult mice induced GCD. Finally, we show that GCD formation can be prevented by infusion of exogenous Reelin. In summary, these studies show that in epilepsy Reelin dysfunction causes GCD development and that Reelin is important for the maintenance of layered structures in the adult brain.
Takao Kohno - One of the best experts on this subject based on the ideXlab platform.
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Regulation of Reelin functions by specific proteolytic processing in the brain.
Journal of biochemistry, 2021Co-Authors: Mitsuharu Hattori, Takao KohnoAbstract:The secreted glycoprotein Reelin plays important roles in both brain development and function. During development, Reelin regulates neuronal migration and dendrite development. In the mature brain, the glycoprotein is involved in synaptogenesis and synaptic plasticity. It has been suggested that Reelin loss or decreased function contributes to the onset and/or deterioration of neuropsychiatric diseases, including schizophrenia and Alzheimer's disease. While the molecular mechanisms underpinning Reelin function remain unclear, recent studies have suggested that the specific proteolytic cleavage of Reelin may play central roles in the embryonic and postnatal brain. In this review, we focus on Reelin proteolytic processing and review its potential physiological roles.
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Physiological significance of proteolytic processing of Reelin revealed by cleavage-resistant Reelin knock-in mice.
Scientific reports, 2020Co-Authors: Eisuke Okugawa, Takao Kohno, Himari Ogino, Tomofumi Shigenobu, Yuko Yamakage, Hitomi Tsuiji, Hisashi Oishi, Mitsuharu HattoriAbstract:Reelin is a secreted protein that plays versatile roles in neuronal development and function. The strength of Reelin signaling is regulated by proteolytic processing, but its importance in vivo is not yet fully understood. Here, we generated Reelin knock-in (PA-DV KI) mice in which the key cleavage site of Reelin was abolished by mutation. As expected, the cleavage of Reelin was severely abrogated in the cerebral cortex and hippocampus of PA-DV KI mice. The amount of Dab1, whose degradation is induced by Reelin signaling, decreased in these tissues, indicating that the signaling strength of Reelin was augmented. The brains of PA-DV KI mice were largely structurally normal, but unexpectedly, the hippocampal layer was disturbed. This phenotype was ameliorated in hemizygote PA-DV KI mice, indicating that excess Reelin signaling is detrimental to hippocampal layer formation. The neuronal dendrites of PA-DV KI mice had more branches and were elongated compared to wild-type mice. These results present the first direct evidence of the physiological importance of Reelin cleavage.
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Physiological significance of proteolytic processing of Reelin revealed by cleavage-resistant Reelin knock-in mice
2020Co-Authors: Eisuke Okugawa, Takao Kohno, Himari Ogino, Tomofumi Shigenobu, Yuko Yamakage, Hitomi Tsuiji, Hisashi Oishi, Mitsuharu HattoriAbstract:Reelin is a secreted protein that plays versatile roles in neuronal development and function, and hypoactivity of Reelin is implicated in many neuropsychiatric disorders. The strength of Reelin signaling is regulated by proteolytic processing, but its importance in vivo is not yet fully understood. Here, we generated Reelin knock-in (PA-DV KI) mice in which the key cleavage site of Reelin was abolished by mutation. As expected, the cleavage of Reelin was severely abrogated in the cerebral cortex and hippocampus of PA-DV KI mice. The amount of Dab1, whose degradation is induced by Reelin signaling, decreased in these tissues, indicating that the signaling strength of Reelin was augmented. The brains of PA-DV KI mice were largely structurally normal, but unexpectedly, the hippocampal layer was disturbed. This phenotype was ameliorated in hemizygote PA-DV KI mice, indicating that excess Reelin signaling is detrimental to hippocampal layer formation. The neuronal dendrites of PA-DV KI mice had more branches and were elongated compared to wild-type mice. These results present the first direct evidence of the physiological importance of Reelin cleavage and suggest that inhibition of Reelin cleavage would counteract neuropsychiatric disorders without causing severe systemic side effects.
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Assay for Reelin-Cleaving Activity of ADAMTS and Detection of Reelin and Its Fragments in the Brain.
Methods in molecular biology (Clifton N.J.), 2019Co-Authors: Himari Ogino, Takao Kohno, Yuko Yamakage, Mihoshi B Yamashita, Mitsuharu HattoriAbstract:Proteolytic cleavage of the secreted signaling protein Reelin has been suggested to play causative roles in many neuropsychiatric and neurodegenerative disorders. Therefore, characterization of the proteolytic activity against Reelin is important not only for understanding how the brain works but also for the development of novel therapy for these disorders. Notably, ADAMTS family proteases are the primary suspects of Reelin-cleaving proteases under many, though not all, circumstances. Here we describe how to measure the Reelin-cleaving activity of ADAMTS (or of any other protease that may cleave Reelin), how to purify the Reelin-cleaving protease ADAMTS-3 from the culture supernatant of cortical neurons, and how to detect endogenous Reelin protein and its fragments in the brain.
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Differential binding of anti-Reelin monoclonal antibodies reveals the characteristics of Reelin protein under various conditions.
Biochemical and biophysical research communications, 2019Co-Authors: Keisuke Ishii, Takao Kohno, Mitsuharu HattoriAbstract:Abstract Reelin is a large secreted protein that is essential for the development and function of the central nervous system. Dimerization and/or oligomerization is required for its biological activity, but the underlying mechanism is not fully understood. There are several widely used anti-Reelin antibodies and we noticed that their reactivity to monomeric or dimeric Reelin protein is different. We also found that their reactivity to Reelin in the solution or in fixed brain tissues also differs. Our results provide the information regarding how the N-terminal region of Reelin folds and contributes to the formation of higher order structure. We also provide a caveat that appropriate use of anti-Reelin antibody is necessary for quantitative analyses.
Eckart Forster - One of the best experts on this subject based on the ideXlab platform.
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Reelin promotes microtubule dynamics in processes of developing neurons
Histochemistry and Cell Biology, 2013Co-Authors: Maurice Meseke, Ersin Cavus, Eckart ForsterAbstract:The extracellular matrix protein Reelin controls radial migration and layer formation of cortical neurons, in part by modulation of cytoskeletal dynamics. A stabilizing effect of Reelin on the actin cytoskeleton has been described recently. However, it is poorly understood how Reelin modulates microtubule dynamics. Here, we provide evidence that Reelin increases microtubule assembly. This effect is mediated, at least in part, by promoting microtubule plus end dynamics in processes of developing neurons. Thus, we treated primary neuronal cultures with nocodazole to disrupt microtubules. After nocodazole washout, we found microtubule reassembly to be accelerated in the presence of Reelin. Moreover, we show that Reelin treatment promoted the formation of microtubule plus end binding protein 3 (EB3) comets in developing dendrites, and that EB3 immunostaining in the developing wild-type neocortex is most intense in the Reelin-rich marginal zone where leading processes of radially migrating neurons project to. This characteristic EB3 staining pattern was absent in reeler. Also reassembly of nocodazole-dispersed dendritic Golgi apparati, which are closely associated to microtubules, was accelerated by Reelin treatment, though with a substantially slower time course when compared to microtubule reassembly. In support of our in vitro results, we found that the subcellular distribution of α-tubulin and acetylated tubulin in reeler cortical sections differed from wild-type and from mice lacking the very low density lipoprotein receptor (VLDLR), known to bind Reelin. Taken together, our results suggest that Reelin promotes microtubule assembly, at least in part, by increasing microtubule plus end dynamics.
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Emerging topics in Reelin function
The European journal of neuroscience, 2010Co-Authors: Eckart Forster, Michael Frotscher, Joachim Herz, Hans H. Bock, Xuejun Chai, Shanting ZhaoAbstract:Reelin signalling in the early developing cortex regulates radial migration of cortical neurons. Later in development, Reelin promotes maturation of dendrites and dendritic spines. Finally, in the mature brain, it is involved in modulating synaptic function. In recent years, efforts to identify downstream signalling events induced by binding of Reelin to lipoprotein receptors led to the characterization of novel components of the Reelin signalling cascade. In the present review, we first address distinct functions of the Reelin receptors Apoer2 and Vldlr in cortical layer formation, followed by a discussion on the recently identified downstream effector molecule n-cofilin, involved in regulating actin cytoskeletal dynamics required for coordinated neuronal migration. Next, we discuss possible functions of the recently identified Reelin-Notch signalling crosstalk, and new aspects of the role of Reelin in the formation of the dentate radial glial scaffold. Finally, progress in characterizing the function of Reelin in modulating synaptic function in the adult brain is summarized. The present review has been inspired by a session entitled 'Functions of Reelin in the developing and adult hippocampus', held at the Spring Hippocampal Research Conference in Verona/Italy, June 2009.
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Role of Reelin in the development and maintenance of cortical lamination
Journal of neural transmission (Vienna Austria : 1996), 2009Co-Authors: Michael Frotscher, Eckart Forster, Hans H. Bock, Xuejun Chai, Carola A. Haas, Shanting ZhaoAbstract:Reelin is a large extracellular matrix molecule, synthesized by early generated Cajal–Retzius cells in the marginal zone of the cortex. It plays an important role in the migration of cortical neurons and the development of cortical lamination. We recently discovered that Reelin is required not only for the formation of cortical layers during development but also for their maintenance in adulthood. Thus, decreased Reelin expression in a mouse model of epilepsy and in epileptic patients was accompanied by a loss of granule cell lamination, called granule cell dispersion, in the dentate gyrus of the hippocampal formation. Moreover, antibody blockade of Reelin in normal, adult mice resulted in granule cell dispersion. Collectively these findings point to a role for Reelin in the formation and maintenance of a laminated cortical structure. How does Reelin act on the cytoskeleton in the migration process of cortical neurons? It has been shown that Reelin signalling involves the lipoprotein receptors apolipoprotein E receptor 2 and very low density lipoprotein receptor, the adapter protein Disabled1, and phosphatidylinositol-3-kinase, but it has remained unclear how activation of the Reelin signalling cascade controls cytoskeletal reorganization. Here, we provide evidence that Reelin signalling leads to serine3 phosphorylation of cofilin, an actin-depolymerizing protein that promotes the disassembly of F-actin. Phosphorylation at serine3 renders cofilin unable to depolymerize F-actin, thereby stabilizing the cytoskeleton. Phosphorylation of cofilin in the leading processes of migrating neurons anchors them to the marginal zone containing Reelin. Our results indicate that Reelin-induced stabilization of the neuronal cytoskeleton is an important component of Reelin’s function in the development and maintenance of cortical architecture.
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Reelin stabilizes the actin cytoskeleton of neuronal processes by inducing n cofilin phosphorylation at serine3
The Journal of Neuroscience, 2009Co-Authors: Xuejun Chai, Eckart Forster, Shanting Zhao, Hans H. Bock, Michael FrotscherAbstract:The extracellular matrix protein Reelin, secreted by Cajal-Retzius cells in the marginal zone of the cortex, controls the radial migration of cortical neurons. Reelin signaling involves the lipoprotein receptors apolipoprotein E receptor 2 (ApoER2) and very low density lipoprotein receptor (VLDLR), the adapter protein Disabled1 (Dab1), and phosphatidylinositol-3-kinase (PI3K). Eventually, Reelin signaling acts on the cytoskeleton; however, these effects on cytoskeletal organization have remained elusive. In Reelin-deficient mutant mice, most cortical neurons are unable to migrate to their destinations, suggesting a role for Reelin signaling in the dynamic cytoskeletal reorganization that is required for neurons to migrate. Here, we show that Reelin signaling leads to serine3 phosphorylation of n-cofilin, an actin-depolymerizing protein that promotes the disassembly of F-actin. Phosphorylation at serine3 renders n-cofilin unable to depolymerize F-actin, thereby stabilizing the cytoskeleton. We provide evidence for ApoER2, Dab1, Src family kinases (SFKs), and PI3K to be involved in n-cofilin serine3 phosphorylation. Phosphorylation of n-cofilin takes place in the leading processes of migrating neurons as they approach the Reelin-containing marginal zone. Immunostaining for phospho-cofilin in dissociated reeler neurons is significantly increased after incubation in Reelin-containing medium compared with control medium. In a stripe choice assay, neuronal processes are stable on Reelin-coated stripes but grow on control stripes by forming lamellipodia. These novel findings suggest that Reelin-induced stabilization of neuronal processes anchors them to the marginal zone which appears to be required for the directional migration process.
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Reelin controls granule cell migration in the dentate gyrus by acting on the radial glial scaffold
Cerebral Cortex, 2003Co-Authors: Michael Frotscher, Carola A. Haas, Eckart ForsterAbstract:Reelin, synthesized and secreted by Cajal-Retzius (CR) cells in the marginal zone of the cortex, is an extracellular matrix protein important for the development of cortical layers. In reeler mutant mice lacking Reelin, there are severe malformations of neocortical and hippocampal lamination. It has been assumed that Reelin acts as a stop signal for migrating neurons. Here we show, by using the dentate gyrus as a model in in vivo studies and in vitro assays, that Reelin exerts its effects, at least in part, by acting on the radial glial scaffold required for neuronal migration. Migration defects of dentate granule cells, reminiscent of those seen in reeler mutants, are observed in tissue from patients with temporal lobe epilepsy (TLE). The extent of granule cell dispersion in TLE was found to be inversely correlated with the number of Reelin mRNA synthesizing CR cells and Reelin mRNA expression as revealed in quantitative RT-PCR studies. These findings show that the Reelin signaling pathway is essential for the correct positioning of human hippocampal neurons and that a Reelin deficiency is involved in the pathological changes associated with epilepsy.
Kazunori Nakajima - One of the best experts on this subject based on the ideXlab platform.
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Reelin transiently promotes n cadherin dependent neuronal adhesion during mouse cortical development
Proceedings of the National Academy of Sciences of the United States of America, 2017Co-Authors: Yuki Matsunaga, Takaki Miyata, Ken Ichiro Kubo, Mariko Noda, Hideki Murakawa, Kanehiro Hayashi, Arata Nagasaka, Seika Inoue, Takashi Miura, Kazunori NakajimaAbstract: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 β-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.
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Reelin has a preventive effect on phencyclidine induced cognitive and sensory motor gating deficits
Neuroscience Research, 2015Co-Authors: Kazuhiro Ishii, Ken Ichiro Kubo, Mariko Noda, Taku Nagai, Yuki Hirota, Toshitaka Nabeshima, Kiyofumi Yamada, Kazunori NakajimaAbstract: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.
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importance of Reelin c terminal region in the development and maintenance of the postnatal cerebral cortex and its regulation by specific proteolysis
The Journal of Neuroscience, 2015Co-Authors: Takao Kohno, Takao Honda, Kazunori Nakajima, Yoshimi Nakano, Ken Ichiro Kubo, Ayaka Tsuchiya, Tatsuro Murakami, Hideyuki Banno, Mitsuharu HattoriAbstract: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.
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regulation of cortical neuron migration by the Reelin signaling pathway
Neurochemical Research, 2011Co-Authors: Takao Honda, Kazuma Kobayashi, Katsuhiko Mikoshiba, Kazunori NakajimaAbstract: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.
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Downregulation of functional Reelin receptors in projection neurons implies that primary Reelin action occurs at early/premigratory stages
The Journal of neuroscience : the official journal of the Society for Neuroscience, 2009Co-Authors: Takayuki Uchida, Kazunori Nakajima, Takaki Miyata, Terumasa Hibi, Atsushi Baba, F. Javier Pérez-martínez, Juan M. Luque, Mitsuharu HattoriAbstract:Reelin signaling is essential for correct development of the mammalian brain. Reelin binds to apolipoprotein E receptor 2 and very low-density lipoprotein receptor and induces phosphorylation of Dab1. However, when and where these reactions occur is essentially unknown, and the primary function(s) of Reelin remain unclear. Here, we used alkaline phosphatase fusion of the receptor-binding region of Reelin to quantitatively investigate the localization of functional Reelin receptors (i.e., those on the plasma membrane as mature forms) in the developing brain. In the wild-type cerebral cortex, they are mainly present in the intermediate and subventricular zones, as well as in radial fibers, but much less in the cell bodies of the cortical plate. Functional Reelin receptors are much more abundant in the Reelin-deficient cortical plate, indicating that Reelin induces their downregulation and that it begins before the neurons migrate out of the intermediate zone. In the wild-type cerebellum, functional Reelin receptors are mainly present in the cerebellar ventricular zone but scarcely expressed by Purkinje cells that have migrated out of it. It is thus strongly suggested that Reelin exerts critical actions on migrating projection neurons at their early/premigratory stages en route to their final destinations, in the developing cerebral cortex and cerebellum.
