若手道場

若手道場1

2021/9/30　10:00～11:00　ZOOM 若手道場 WD1-1 正常脳と傷害脳内において鎖状移動する新生ニューロンの細胞間接着制御 Regulation of cellular adhesion in chains of migrating neuroblasts in the normal and injured brain ^○松本真実^1,2, Masato Sawada¹, Katsuyoshi Matsushita¹, Huy Bang Nguyen¹, Truc Quynh Thai¹, Nobuhiko Ohno¹, Kazunobu Sawamoto¹ 1.自然科学研究機構　生理学研究所　電子顕微鏡室, 2.Section of Electron Microscopy, Supportive Center for Brain Research, National Institute for Physiological Sciences, 3.Department of Biological Sciences, Osaka University, 4.Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, 5.Division of Histology and Cell Biology, Department of Anatomy, Jichi Medical University School of Medicine, 6.Division of Neural Development and Regeneration, National Institute for Physiological Sciences ^○Mami Matsumoto^1,2, Masato Sawada¹, Katsuyoshi Matsushita¹, Huy Bang Nguyen¹, Truc Quynh Thai¹, Nobuhiko Ohno¹, Kazunobu Sawamoto¹ 1.Department of Developmental and Regenerative Biology, Nagoya City University Graduate School of Medical Sciences, 2.Section of Electron Microscopy, Supportive Center for Brain Research, National Institute for Physiological Sciences, 3.Department of Biological Sciences, Osaka University, 4.Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, 5.Division of Histology and Cell Biology, Department of Anatomy, Jichi Medical University School of Medicine, 6.Division of Neural Development and Regeneration, National Institute for Physiological Sciences Neural stem cells reside and continuously produce neuroblasts in the adult rodent ventricular-subventricular zone (V-SVZ). These neuroblasts form chain-like cell aggregates and migrate through the rostral migratory stream toward the olfactory bulb, where they differentiate into mature interneurons. Within chains, migrating neuroblasts show saltatory movement along their neighboring ones, in which they extend a long leading process followed by somal translocation. V-SVZ-derived neuroblasts migrating toward a lesion also form chain-like aggregates in injured brain tissues, suggesting that chain formation is important for the migration of neuroblasts in the adult brain. However, it remains unknown how these neuroblasts control their adhesion in chains. To observe the cellular adhesions between chain-forming neuroblasts in the normal brain, we performed electron microscopic analyses. Three-dimensional distribution of cellular adhesions between migrating neuroblasts visualized using serial block-face scanning electron microscopy (SBF-SEM) suggests that cellular adhesion is dynamically controlled during their saltatory movement. To investigate the effect of cellular adhesion on neuronal migration, we used a mathematical model of collective cell migration. The results of computational analyses using our mathematical model revealed that efficiency chain migration depends on appropriate levels of cellular adhesion. Furthermore, we found that the cellular adhesion patterns between neuroblasts were altered in the injured brain. Taken together, these results suggest that the regulation of cellular adhesions in chains is important for efficient neuroblast migration in the adult brain.		2021/9/30　10:00～11:00　ZOOM 若手道場 WD1-2 マウスの大脳新皮質神経細胞移動に関与するカドヘリンの検索 Screening for the cadherin molecules that are involved in neuronal migration in the mouse cerebral ^○齋藤里香穂¹, 野﨑恵太¹, 佐野ひとみ¹, 廣田ゆき¹, 仲嶋一範¹ 1.慶應義塾大学　医学部解剖学教室　仲嶋研究室, 2.Division of Pharmacology, Faculty of Pharmacy, Keio University ^○Rikaho Saito¹, 恵太野﨑¹, ひとみ佐野¹, ゆき廣田¹, 一範仲嶋¹ 1.Department of Anatomy, Keio University School of Medicine, 2.Division of Pharmacology, Faculty of Pharmacy, Keio University Various cadherins are expressed in the developing brain, but in what aspect of development each cadherin is involved remains poorly understood. Neurons in the neocortex, which greatly develops especially in higher mammals, compose a 6-layered structure parallel to the brain surface. Most of the excitatory neurons are born in the ventricular zone and subventricular zone and migrate radially toward the brain surface. Upon arriving near the outermost part of the cortical plate, they finally migrate in the terminal translocation mode, in which neurons shorten their leading processes while maintaining their tip in the marginal zone (MZ) to pull up their cell bodies to just beneath the MZ. In this study, we aimed to identify cadherins that are involved in neuronal migration during neocortical development. We first searched for the cadherins expressed in migrating neurons in the developing neocortex using a public single cell RNA-seq database and Allen atlas of mRNA expression in the brain. We then investigated their expression patterns in detail in the developing neocortex using fluorescent in situ HCR and immunohistochemical analyses. The shRNA-mediated KD experiments revealed that some cadherins are required for neuronal migration in the intermediate zone, while inhibition of other cadherins affected the terminal translocation. We created expression plasmids for these cadherins fused with a fluorescent tag, transfected them into migrating neurons in the developing neocortex, and observed the localization of the tagged proteins. Results showed that some cadherins whose inhibition affected the terminal translocation tended to localize on the neurites extending into the MZ. These results suggest possible roles of these cadherins in neuronal migration.

2021/9/30　10:00～11:00　ZOOM 若手道場 WD1-3 C9ORF72遺伝子変異FTD患者iPS細胞由来神経細胞を用いた病態モデリング Pathophysiological model using iPSC-derived cortical neurons from FTD patients with C9ORF72 repeat expansion ^○佐藤月花, Kent Imaizumi, Hideyuki Okano 未記入 ^○Tsukika Sato, Kent Imaizumi, Hideyuki Okano Department of Physiology, Keio University School of Medicine The C9ORF72 hexanucleotide repeat expansion is the most common genetic cause of　familial frontotemporal dementia (FTD), which mainly affects the frontal and temporal lobes of the cerebral cortex. Some studies have recently suggested that one of the major pathomechanisms underlying FTD is the generation of toxic dipeptide repeat (DPR) proteins produced by C9ORF72 expansion. However, DPR-driven pathogenesis of FTD has not been fully verified in human neural cell models. While the development of human induced pluripotent stem cell (iPSC) technology has enabled the generation of patient-derived neural cells in a dish, there are no reports on iPSC-based modeling of C9ORF72-mediated FTD. In this study, we aimed to generate pathophysiological disease models using iPSCs-derived cortical neurons from FTD patients with C9ORF72 repeat expansion. First, we succeeded in generating frontal lobe-specific neurons from patient-derived iPSCs by modulating Wnt and FGF8 signaling pathway. Gene expression patterns of generated neurons were closely similar to those of human embryonic frontal lobes. Next, we found that p62 protein, which associated with autophagy, were accumulated in frontal lobe-specific neurons derived from FTD patient iPSCs, whereas such phenotypes were not detected in neurons with other brain region identities than the frontal lobe, suggesting that the frontal lobe-specific phenotypes of FTD could be recapitulated in our culture system. p62 accumulation was also observed when DPR proteins were overexpressed in neurons from healthy control iPSCs, which indicates that DPR protein toxicity would primarily underlie the FTD pathomechanisms. Further studies into the DPR protein toxicity by C9ORF72 repeat expansions should be explored in this iPSC-based FTD models.