7 results on '"Kano, Masanobu"'
Search Results
2. Multiple Phases of Climbing Fiber Synapse Elimination in the Developing Cerebellum
- Author
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Kano, Masanobu, Watanabe, Takaki, Uesaka, Naofumi, and Watanabe, Masahiko
- Published
- 2018
- Full Text
- View/download PDF
3. Climbing fiber synapse elimination in cerebellar Purkinje cells
- Author
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Watanabe, Masahiko and Kano, Masanobu
- Subjects
cerebellum ,parallel fiber ,climbing fiber ,Purkinje cell ,synapse elimination ,development - Abstract
Innervation of Purkinje cells (PCs) by multiple climbing fibers (CFs) is refined into mono-innervation during the first three postnatal weeks of rodents' life. In this review article, we will integrate the current knowledge on developmental process and mechanisms of CF synapse elimination. In the "creeper" stage of CF innervation (postnatal day 0 (P0)∼), CFs creep among PC somata to form transient synapses on immature dendrites. In the "pericellular nest" stage (P5∼), CFs densely surround and innervate PC somata. Then, CF innervation is displaced to the apical portion of PC somata in the "capuchon" stage (P9∼), and translocate to dendrites in the "dendritic" (P12∼) stage. Along with the developmental changes of CF wiring, functional and morphological distinctions become larger among CF inputs. PCs are initially innervated by >5 CFs with similar strengths (∼P3). Only a single CF is selectively strengthened during P3-P7 (functional differentiation), and undergoes dendritic translocation from P9 on (dendritic translocation). Following the functional differentiation, perisomatic CF synapses are eliminated non-selectively, which proceeds in two distinct phases. The early phase (P7-P11) is conducted independently of parallel fiber (PF)-PC synapse formation, while the late phase (P12-P17) critically depends on it. The P/Q-type voltage-dependent Ca2+ channel in PCs triggers selective strengthening of single CF inputs, promotes dendritic translocation of the strengthened CFs, and drives the early phase of CF synapse elimination. On the other hand, the late phase is mediated by mGluR1-Gαq-PLCβ4-PKCγ signaling cascade in PCs driven at PF-PC synapses, whose structural connectivity is stabilized and maintained by the GluRδ2-Cbln1-neurexin system.
- Published
- 2011
4. Role of pre- and postsynaptic activity in thalamocortical axon branching.
- Author
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Yamada, Akito, Uesaka, Naofumi, Hayano, Yasufumi, Tabata, Toshihide, Kano, Masanobu, and Yamamoto, Nobuhiko
- Subjects
AXONS ,POTASSIUM channels ,NEUROPHYSIOLOGY ,GENE transfection ,CELL physiology ,PROTEINS - Abstract
Axonal branching is thought to be regulated not only by genetically defined programs but also by neural activity in the developing nervous system. Here we investigated the role of preand postsynaptic activity in axon branching in the thalamocortical (IC) projection using organotypic coculture preparations of the thalamus and cortex. Individual TC axons were labeled with enhanced yellow fluorescent protein by transfection into thalamic neurons. To manipulate firing activity, a vector encoding an inward rectifying potassium channel (Kir2.1) was introduced into either thalamic or cortical cells. Firing activity was monitored with multielectrode dishes during culturing. We found that axon branching was markedly suppressed in Kir2.1-overexpressing thalamic cells, in which neural activity was silenced. Similar suppression of TC axon branching was also found when cortical cell activity was reduced by expressing Kir2.1. These results indicate that both preand postsynaptic activity is required for TC axon branching during development [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
5. P/Q-Type Ca2+ Channel α1A Regulates Synaptic Competition on Developing Cerebellar Purkinje Cells.
- Author
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Miyazaki, Taisuke, Hashimoto, Kouichi, Hee-Sup Shin, Kano, Masanobu, and Watanabe, Masahiko
- Subjects
NEURONS ,PURKINJE cells ,CALCIUM channels ,SYNAPSES ,NEUROSCIENCES - Abstract
Synapse formation depends critically on the competition among inputs of multiple sources to individual neurons. Cerebellar Purkinje cells have highly organized synaptic wiring from two distinct sources of excitatory afferents. Single climbing fibers innervate proximal dendrites of Purkinje cells, whereas numerous parallel fibers converge on their distal dendrites. Here, we demonstrate that the P/Q-type Ca
2+ channel α1A, a major Ca2+ channel subtype in Purkinje cells, is crucial for this organized synapse formation. In the α1A knock-out mouse, many ectopic spines were protruded from proximal dendrites and somata of Purkinje cells. Innervation territory of parallel fibers was expanded proximally to innervate the ectopic spines, whereas that of climbing fibers was regressed to the basal portion of proximal dendrites and somata. Furthermore, multiple climbing fibers consisting of a strong climbing fiber and one or a few weaker climbing fibers, persisted in the majority of Purkinje cells and were cowired to the same somata, proximal dendrites, or both. Therefore, the lack of α1A results in the persistence of parallel fibers and surplus climbing fibers, which should normally be expelled from the compartment innervated by the main climbing fiber. These results suggest that a P/Q-type Ca2+ channel α1A fuels heterosynaptic competition between climbing fibers and parallel fibers and also fuels homosynaptic competition among multiple climbing fibers. This molecular function facilitates the distal extension of climbing fiber innervation along the dendritic tree of the Purkinje cell and also establishes climbing fiber monoinnervation of individual Purkinje cells. [ABSTRACT FROM AUTHOR]- Published
- 2004
- Full Text
- View/download PDF
6. Patterns of expression for the mRNA corresponding to the four isoforms of phospholipase Cβ in mouse brain.
- Author
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Watanabe, Masahiko, Nakamura, Michiko, Sato, Kazunori, Kano, Masanobu, Simon, Melvin I., and Inoue, Yoshiro
- Subjects
PHOSPHOLIPASE C ,PURKINJE cells ,TELENCEPHALON ,MESSENGER RNA ,PHYSIOLOGY ,REACTIVITY (Chemistry) - Abstract
Ligand binding to neurotransmitter and hormone receptors which couple to the Gq subclass of GTP-binding protein leads to the activation of phospholipase Cβ (PLCβ) which hydrolyses phosphatidyl-inositol 4,5-bisphosphate, yielding a pair of second messengers, diacylglycerol and inositol 1,4,5-trisphosphate (IP[sub 3]). The expression of PLCβ1–4 mRNAs was comparatively examined by in situ hybridization in the mouse brain. In adults, PLCβ1 mRNA was expressed predominantly in the telencephalon, including the cerebral cortex, hippocampus, amygdala, lateral septum and olfactory bulb, with little expression in most thalamic nuclei. PLCβ2 mRNA was distributed in the white matter, suggesting its expression in non-neuronal cells, most likely oligodendrocytes. PLCβ3 mRNA was specifically expressed in cerebellar Purkinje cells. The highest levels of PLCβ4 mRNA were detected in Purkinje cells. High levels of PLCβ4 mRNA were also found in the thalamus and medial septum, whereas weak signals were detected in most telencephalic regions, thus showing an expression pattern almost reciprocal to that of PLCβ1 mRNA. During development, such characteristic regional expression of PLCβ1 and PLCβ4 were observed starting in late foetal stages, while specific expression of PLCβ2 and PLCβ3 appeared in early postnatal stages. We conclude that despite the existence of four PLCβ isoforms, only one or two of them is expressed in individual neurons and glial cells. The distinct expression of PLCβs provides a molecular basis for analysing the nature of the specific signal transduction pathway leading to the production of diacylglycerol and IP[sub 3] in distinct cell types and in different regions of the brain. [ABSTRACT FROM AUTHOR]
- Published
- 1998
- Full Text
- View/download PDF
7. mGluR1 signaling in cerebellar Purkinje cells: Subcellular organization and involvement in cerebellar function and disease.
- Author
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Yamasaki, Miwako, Aiba, Atsu, Kano, Masanobu, and Watanabe, Masahiko
- Subjects
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PURKINJE cells , *CEREBELLAR cortex , *NEURAL pathways , *COGNITIVE ability , *GLUTAMATE receptors , *LABORATORY mice - Abstract
The cerebellum is essential for the control, coordination, and learning of movements, and for certain aspects of cognitive function. Purkinje cells are the sole output neurons in the cerebellar cortex and therefore play crucial roles in the diverse functions of the cerebellum. The type 1 metabotropic glutamate receptor (mGluR1) is prominently enriched in Purkinje cells and triggers downstream signaling pathways that are required for functional and structural plasticity, and for synaptic responses. To understand how mGluR1 contributes to cerebellar functions, it is important to consider not only the operational properties of this receptor, but also its spatial organization and the molecular interactions that enable its proper functioning. In this review, we highlight how mGluR1 and its related signaling molecules are organized into tightly coupled microdomains to fulfill physiological functions. We also describe emerging evidence that altered mGluR1 signaling in Purkinje cells underlies cerebellar dysfunction in ataxias of human patients and mouse models. • mGluR1 signaling in Purkinje cells is crucial for various cerebellar functions. • mGluR1 triggers intracellular pathways for neural plasticity and modulation. • mGluR1 and its interacting partners are arranged into tightly coupled microdomains. • mGluR1 signaling is a promising therapeutic target for cerebellar dysfunctions. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
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