TOP ＞ 一般口演

一般口演 神経発生とグリア発生 3 Neurogenesis and Gliogenesis 3 座長：津田 佐知子（埼玉大学） 2022年7月3日　11:00～11:15　沖縄コンベンションセンター 会議場B1　第3会場 4O03a1-01 ミクログリアによるフォスファチジルセリン依存的な成体新生ニューロンのシナプス貪食 Synaptic pruning of murine adult-born neurons by microglia depends on phosphatidylserine *榑松 千紘(1)、澤田 雅人(1,2)、大村谷 昌樹(3)、田中 基樹(4)、久保山 和哉(1)、荻野 崇(1)、松本 真実(1,2)、大石 久史(1)、稲田 浩之(2)、Huy Bang Nguyen(2,5)、Truc Quynh Thai(2,6)、高坂 新一(7)、大野 伸彦(2,8)、山田 麻紀(9)、浅井 真人(4)、曽我部 正博(10)、鍋倉 淳一(2)、浅野 謙一(11)、田中 正人(11)、澤本 和延(1,2) 1. 名古屋市立大学大学院医学研究科、2. 自然科学研究機構生理学研究所、3. 兵庫医科大学、4. 愛知県医療療育総合センター、5. ベトナム・Ho Chi Minh医科薬科大学、6. ベトナム・Pham Ngoc Thach医科大学、7. 国立精神・神経医療研究センター、8. 自治医科大学医学部、9. 徳島文理大学、10. 名古屋大学大学院医学研究科、11. 東京薬科大学生命科学部 *Chihiro Kurematsu(1), Masato Sawada(1,2), Masaki Ohmuraya(3), Motoki Tanaka(4), Kazuya Kuboyama(1), Takashi Ogino(1), Mami Matsumoto(1,2), Hisashi Ohishi(1), Hiroyuki Inada(2), Huy Bang Nguyen(2,5), Truc Quynh Thai(2,6), Shinichi Kohsaka(7), Nobuhiko Ohno(2,8), Maki Yamada(9), Masato Asai(4), Masahiro Sokabe(10), Junichi Nabekura(2), Kenichi Asano(11), Masato Tanaka(11), Kazunobu Sawamoto(1,2) 1. Nagoya City Univ Grad Sch Med Sci, Nagoya, Japan, 2. NIPS, Okazaki, Japan, 3. Hyogo Col Med, Nishinomiya, Japan, 4. Aichi Dev Disabi Ctr, Kasugai, Japan, 5. Univ of Med and Pharm at Ho Chi Minh City (UMP), Ho Chi Minh city , Vietnam, 6. Pham Ngoc Thach Univ of Med, Ho Chi Minh city , Vietnam, 7. Natl Ctr of Neurol Psychiat, Kodaira, Japan, 8. Jichi Med Univ, Sch Med, Shimotsuke, Japan, 9. Tokushima Bunri Univ, Sanuki, Japan, 10. Nagoya Univ Grad Sch Med, Nagoya, Japan, 11. Tokyo Univ Pharm Life Sci, Hachioji, Japan Keyword: adult neurogenesis, microglia, synapse, phagocytosis In the adult brain, neural stem cells in the ventricular-subventricular zone of the lateral ventricles and the subgranular zone of the hippocampal dentate gyrus continuously generate new neurons, which are integrated into the olfactory bulb (OB) and hippocampal circuits, respectively. Although various molecular mechanisms for the synapse formation of adult-born neurons have been reported, how synaptic pruning, another critical step for the functional integration of new neurons into the circuits, is controlled in adult-born neurons is not fully understood. Microglia, the professional phagocytes in the central nervous system, contribute to various facets of adult neurogenesis. Dead cells in the adult neurogenic regions are rapidly eliminated by microglial phagocytosis. Phosphatidylserine (PS) is an important membrane phospholipid that serves as an eat-me signal for phagocytes to engulf dead cells. Recent studies reported that synapses present PS and are phagocytosed by microglia during postnatal brain development. However, the localization and function of PS in synaptic pruning by microglia in vivo are still unknown. Here we show that synaptic pruning of adult-born neurons by microglia depends on phosphatidylserine, whose exposure on dendritic spines is inversely correlated with their input activity. To study the role of PS in spine pruning by microglia in vivo, we developed an inducible transgenic mouse line, in which the exposed PS is masked by a dominant-negative form of milk fat globule-EGF-factor 8 (MFG-E8), MFG-E8D89E. In this transgenic mouse, the spine pruning of adult-born neurons by microglia is impaired in the OB and hippocampus. Furthermore, the electrophysiological properties of these adult-born neurons are altered in MFG-E8D89E mice. These data suggest that PS is involved in the microglial spine pruning and functional maturation of adult-born neurons. The MFG-E8D89E-based genetic approach shown in this study has broad applications for understanding the biology of PS-mediated phagocytosis in vivo. 2022年7月3日　11:15～11:30　沖縄コンベンションセンター 会議場B1　第3会場 4O03a1-02 DNAポリメラーゼβ欠損は大脳皮質神経細胞の発生において体細胞突然変異を誘発させる Loss of DNA polymerase β induces somatic mutations in developing cortical neurons *菅生 紀之(1)、松本 理沙(1)、中山 宙(1)、松本 敏幸(1)、藤本 翔太(1)、佐藤 康成(2)、若山 清香(3)、若山 照彦(3)、内村 有邦(2)、八木 健(1) 1. 大阪大学、2. 放射線影響研究所、3. 山梨大学 *Noriyuki Sugo(1), Risa Matsumoto(1), Hiro Nakayama(1), Toshiyuki Matsumoto(1), Shota Fujimoto(1), Yasunari Satoh(2), Sayaka Wakayama(3), Teruhiko Wakayama(3), Arikuni Uchimura(2), Takeshi Yagi(1) 1. Osaka University, 2. Radiation Effects Research Foundation, 3. University of Yamanashi Keyword: DNA repair, mutation, genome, epigenetics Cortical developmental disorders, such as autism spectrum disorders and schizophrenia, are thought to be attributable to somatic mutations in neurons. An intriguing question is what mechanism causes genome instability and subsequent mutations in the developing nervous system. Our previous studies demonstrate that loss of DNA polymerase β (Polβ), a component of the base excision repair, in cortical progenitors leads to DNA double-strand breaks during replication, which remain in postmitotic immature neurons (Onishi et al., J Neurosci, 2017). Polβ also maintains genome stability in the active DNA demethylation that occurs during early postnatal neuronal development, thereby contributing to differentiation and learning and memory (Uyeda et al., J Neurosci, 2020). However, how the loss of Polβ influences on neuronal genome at nucleotide-resolution remains unknown. To address this issue, we established ES cells from neuronal nuclear transfer embryos using mouse cloning technology and analyzed these genomes, which reflects the neuronal genome. The cloned embryos were generated from cortical neuronal nuclei in both two littermate E18.5 Emx1-Cre/Polβf/f embryos lacking Polβ in neural progenitors of the dorsal telencephalon and two control Polβf/f embryos. The three to four ES clones from neuronal nuclei in each cortex were subjected to whole genome sequencing for detecting de novo mutations, respectively. Individual ES clones had unique somatic mutations including 30-140 single-nucleotide variants (SNVs), 90-160 insertions and deletions (indels). We found that the number of indels, but not SNVs, proximal to CpG sites significantly increased in individual Polβ-deficient ES cell clones compared to controls, suggesting that Polβ deficiency induces mutations in the process of active DNA demethylation during cortical neurogenesis. Several indels were also found in coding regions of genes associated with autism spectrum disorders. Moreover, the number of structural variants (SVs), which caused large deletions, increased in Polβ-deficient ES cell clones than controls. These results suggest that accumulation of intermediates in Polβ-dependent active DNA demethylation during neurogenesis and neuronal differentiation induces indels and SVs, thereby affecting brain function throughout life. 2022年7月3日　11:30～11:45　沖縄コンベンションセンター 会議場B1　第3会場 4O03a1-03 マウスナー細胞の軸索起始部を取り囲む特徴的なグリア組織 Axon Cap Glia のゼブラフィッシュ幼生から成体までの発生過程 Development of the axon cap glia, a specialized structure surrounding the initial segment of the Mauthner cell, from larval to adult in zebrafish. *岩谷 将太(1)、青木 澪(1)、二階堂 昌孝(1)、八田 公平(1) 1. 兵庫県立大学大学院 *Shota Iwatani(1), Mio Aoki(1), Masataka Nikaido(1), Kohei Hatta(1) 1. Grad.Sch Sci.Univ of Hyogo, Hyogo, Japan Keyword: Transgenic, Development of Glia, Adult Brain, Escape Mauthner (M-) cells are giant excitatory interneurons that exist in pairs on the left and right sides of the rhombencephalon's fourth segment in teleost. They control C-start escape response, a reflex in which the body moves away from the stimulus input to initiate escape behavior. The initial segment of the Mauthner cell is surrounded by axons and terminals of glutamatergic excitatory spiral neurons and glycinergic inhibitory feed-back neurons. This specialized structure is called Axon Cap. In addition, in many teleost species, a specialized group of glial cells, called Axon Cap Glia (ACG), surrounds the Axon Cap to form an electrical insulator. This, in turn, creates depolarizing field potential, derived from action potentials of the inhibitory feed-back neurons, causing an unusually rapid ‘electrical inhibition' before the chemical inhibition via synapses acts (Furukawa and Furshpan, 1963; Hatta and Korn, 1998). Until recently, there were no markers for these glial cells, and research had not progressed. We now discovered that a transgenic fish (Ohno et al. 2021) expresses GFP in ACG, as well as their possible precursors. Based on the observation on the developmental change in the GFP expression, we have proposed that the Axon Cap Glia precursors are initially located at the midline and migrate along the Radial Glia from the ventricular zone to the initial segment of the M-cells from 2.5 dpf, surrounding the Axon Cap by 3 dpf. Here we show that the GFP is also expressed in the ACG in the adult zebrafish. We found a spherical fluorescent ball around the initial segment connected to the midline with a fine string. Different from the larva, GFP expression is also found in the Axon Cap, indicating that the Axon Cap is now filled with processes of the ACG. To elucidate the possible interactions between the M-cell and ACG, we are currently testing the effect of the ablation of either ACG or the M-cell at the larval stage on the development of the other as well as on the escape behavior.