一般口演
神経変性疾患 2
Neurodegenerative Disorders 2
座長：篠崎 陽一（山梨大学） |
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| 2022年7月3日 9:00～9:15 沖縄コンベンションセンター 会議場B2 第5会場
4O05m1-01
エソサクシミドはSCA42モデルマウスの臨床学的、病理学的表現型を改善させる
Ethosuximide improves clinical and pathological phenotypes of SCA42 mouse model
*大久保 正紀(1)、土井 宏(1)、橋口 俊太(1)、國井 美紗子(1)、高橋 慶太(1)、多田 美紀子(1)、田中 健一(1)、竹内 英之(1)、石川 太郎(2)、田中 章景(1)
1. 横浜市立大学医学部神経内科学・脳卒中医学教室、2. 東京慈恵医科大学薬理学
*Masaki Okubo(1), Hiroshi Doi(1), Shunta Hashiguchi(1), Misako Kunii(1), Keita Takahashi(1), Mikiko Tada(1), Kenichi Tanaka(1), Hideyuki Takeuchi(1), Taro Ishikawa(2), Fumiaki Tanaka(1)
1. Department of Neurology and Stroke Medicine, Yokohama City University Graduate School of Medicine, 2. Department of Pharmacology, The Jikei University School of Medicine
Keyword: SCA42, ethosiximide, T-type voltage-gated Calcium channel, purkinje cell
Objective: Spinocerebellar ataxia 42 (SCA42) is a neurodegenerative disorder caused by c.5144G>A(p.Arg1715His) mutation in CACNA1G, which encodes the T-type voltage-gated calcium channel CaV3.1. We previously established a knock-in mouse model of SCA42 by introducing a c.5168G> A (p.Arg1723His) mutation in Cacna1g which corresponding to the mutation identified in the SCA42 patients, and reported that the mutation directly caused progressive ataxia, Purkinje cell degeneration, and the electrophysiological abnormalities. The aim of this study is to elucidate whether a T-type calcium blocker ameliorates ataxic symptoms, neuronal dysfunction, and neurodegeneration in the SCA42 mouse model. Methods: Under the treatment of SCA42 mice by ethosuximide, a T-type calcium channel blocker, we performed behavioral (Rotarod test, foot print test), pathological (Purkinje cell density and area of cerebellum), and electrophysiological (whole cell patch clamp techniques) analyses. Results: Compared to untreated mice, ethosuximide-treated mice showed significantly improved ataxic phenotype at the age of 30-50 weeks and also decreased Purkinje cell loss at 50 weeks old in the sagittal cerebellar slice. The results of electrophysiological analysis of HEK293T cells co-expressing DsRed and wildtype or mutant CaV3.1 indicated that ethosuximide modulates the voltage dependence of mutant CaV3.1. Conclusions: Using the animal model of SCA42, we demonstrated that ethosuximide suppresses Purkinje cell degeneration and improves ataxic phenotype by modulating the voltage dependence of mutant CaV3.1. | | 2022年7月3日 9:15～9:30 沖縄コンベンションセンター 会議場B2 第5会場
4O05m1-02
アストロサイトのABCA1欠損による細胞非自律的視神経症発症機構の解明
ABCA1 deficiency in astrocytes triggers non-cell-autonomous optic neuropathy via neuroinflammation and excitotoxicity
*篠崎 陽一(1,2)、ルング アレックス(3)、行方 和彦(4)、大野 伸彦(5,6)、繁冨 英治(2,1)、柏木 賢治(7)、原田 高幸(4)、大沼 信一(3)、小泉 修一(1,2)
1. 山梨大学大学院総合研究部医学域基礎医学系薬理学講座、2. 山梨大学GLIAセンター、3. ロンドン大学眼科学研究所、4. 東京都医学研視覚病態、5. 生理研・超微形態、6. 自治医大・解剖、7. 山梨大学大学院総合研究部医学域臨床医学系眼科学講座
*Youichi Shinozaki(1,2), Alex Leung(3), Kazuhiko Namekata(4), Nobuhiko Ohno(5,6), Eiji Shigetomi(2,1), Kenji Kashiwagi(7), Takayuki Harada(4), Shin-Ichi Ohnuma(3), Schuichi Koizumi(1,2)
1. Dept Neuropharmacol, Grad Sch Med, Univ Yamanashi, Yamanashi, Japan, 2. GLIA Cent, Grad Sch Med, Univ Yamanashi, Yamanashi, Japan, 3. UCL Inst Ophthalmol, UCL, London, UK, 4. Vis Res Project, Tokyo Metr Inst Med, Tokyo, Japan, 5. Div Ultrastract Res, Natl Inst Physiol Sci, Aichi, Japan, 6. Div Anatomy, Jichi Med Univ, Tochigi, Japan, 7. Dept Ophthalmol, Interdisp Grad Sch Med, Univ Yamanashi, Yamanashi, Japan
Keyword: Astrocytes, ABCA1, Glaucoma, Retinal ganglion cells
Glaucoma is progressive optic neuropathy which is the first cause of blindness in Japan. Degeneration of retinal ganglion cells (RGCs), a subtype of retinal neurons that transduces visual information to the brain, causes visual impairment in this disease. Although an elevated intraocular pressure (IOP) has long been considered as a primal cause of the pathology, it has become apparent that many risk factors other than IOP are involved in the etiology of glaucoma. Genome-wide association studies have shown that single nucleotide polymorphism of the gene encoding ATP-binding cassette transporter A1 (ABCA1), a membrane cholesterol transporter, is associated with both normal and high IOP types of glaucoma in humans, but the pathological mechanism remains unknown. Here, we report that loss of ABCA1 in astrocytes causes non-cell-autonomous normal-tension glaucoma (NTG)-like optic neuropathy. ABCA1flox/flox::GFAP-Cre (Glia-KO) mice showed no RGC degeneration at 3 months old but showed apoptotic RGC loss at 12 months old. Glia-KO mice at 12 months old also showed glaucoma-related pathological changes such as thinning of retinal nerve fiber layer (NFL), dendritic atrophy of RGCs, synapse and optic nerve loss, and visual dysfunction. We also found age-associated biphasic changes in astrocyte reactivity in Glia-KO mice. Astrocytes became reactive at 3 months old but inactivated at 12 months old. Single-cell RNA sequencing revealed that chemokine pathways such as CXCL12-CXCR4 and CCL5-CCR5 pathways were up-regulated in RGCs and astrocytes. CXCL12 and CCL5 were up-regulated in astrocytes in vitro and in vivo. Because CXCR4 and CCR5 were highly expressed in RGCs, the astrocyte-derived chemokines might affect RGC functions. We identified a novel RGC subclass enriched in a unique set of N-methyl-D-aspartate (NMDA) subunit genes, implicating higher sensitivity to excitotoxicity. Intravitreal NMDA injection caused exacerbated RGC damages in Glia-KO mice than that of Ctr mice. To test the possible link between chemokine signals and excitotoxicity, we tested the blockade of chemokine signals and found that the higher sensitivity of RGC to NMDA was induced by the chemokine signals. Taken together, our data demonstrate that astrocytic dysfunction causes non-cell-autonomous NTG-like optic neuropathy in which neuroinflammation and excitotoxicity were essential. | | 2022年7月3日 9:30～9:45 沖縄コンベンションセンター 会議場B2 第5会場
4O05m1-03
小胞体・ミトコンドリア連関の破綻はTANK結合キナーゼ1（TBK1）を不活性化し、ストレス顆粒形成と運動機能の障害を引き起こす
Disruption of mitochondria-associated membrane inactivates TANK-binding kinase 1, leading to impairment of stress granule formation and motor dysfunction
*渡邊 征爾(1)、大岩 康太郎(1,2)、山中 宏二(1)
1. 名古屋大学環境医学研究所、2. 名古屋大学医学系研究科
*Seiji Watanabe(1), Kotaro Oiwa(1,2), Koji Yamanaka(1)
1. RIEM, Nagoya Univ, Aichi, Japan, 2. Grad Sch Med, Nagoya Univ, Aichi, Japan
Keyword: mitochondria-associated membranes, TANK-binding kinase 1 (TBK1), Sigma 1 receptor, amyotrophic lateral sclerosis (ALS)
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by a selective loss of motor neurons. We previously demonstrated that disruption of the mitochondria-associated membrane (MAM), a contact site of the endoplasmic reticulum (ER) and mitochondria, was involved in ALS pathogenesis. MAM was widely compromised by various ALS-related genes, suggesting that MAM disruption is one of the key pathomechanisms of ALS. Our previous study also showed that abnormal intracellular calcium flux caused by MAM deficiency is closely associated with motor neuron degeneration in ALS. However, it is not fully understood how MAM disruption induces motor neuron degeneration.
In this study, we focused on TANK-binding kinase 1 (TBK1), whose loss of function is considered as a cause of familial ALS. We found that TBK1 activity was significantly decreased in the brains of sporadic ALS patients and SOD1-linked ALS model mice. Intriguingly, TBK1 was also inactivated by MAM impairment induced by a loss of Sigma 1 receptor (Sig1R), another ALS-causative gene product, and a MAM-specific molecular chaperone. TBK1 partially translocated into MAM, and preventing the MAM translocation inactivated TBK1. These results suggest that TBK1 activity is dependent on MAM integrity. Furthermore, TBK1 depletion inhibited the formation of membrane-less organelles composed of RNA and RNA-binding proteins called stress granules (SG). TBK1 deficiency increased apoptotic cells under arsenite-induced oxidative stress conditions in HeLa cells and decreased rotarod score of arsenite-treated Sig1R knock-out mice. These findings suggest that TBK1 regulates cellular stress response through SG formation, which might be compromised in ALS.
In conclusion, we first revealed that MAM integrity is essential for maintaining the TBK1 activity and that reduced TBK1 activity may contribute to motor neurodegeneration by increasing neuronal stress vulnerability. Further study to elucidate how MAM regulates TBK1 activity may lead to a future therapeutic strategy for ALS. | | 2022年7月3日 9:45～10:00 沖縄コンベンションセンター 会議場B2 第5会場
4O05m1-04
神経変性疾患における免疫依存性神経細胞障害機序の解析
Molecular mechanism of immune-mediated neuronal cell death and its relevance to pathogenesis of neurodegenerative diseases
*高橋 文緒(1,3)、張 晨陽(1)、北條 浩彦(2)、 Raveney Ben (1)、山村 隆(1)、林 宣宏(3)、大木 伸司(1)
1. 国立精神・神経医療研究センター 免疫研究部、2. 国立精神・神経医療研究セ・神経研・神経薬理 、3. 東工大・院生命理工
*Fumio Takahashi(1,3), Chenyang Zhang(1), Hirohiko Hohjoh(2), Ben Raveney(1), Takashi Yamamura(1), Nobuhiro Hayashi(3), Shinji Oki(1)
1. Dept. of Immunol., Natl Inst Neurol. NCNP , 2. Dept. of Mol Pharmacol., Natl Inst Neurol. NCNP, 3. Grad. Sch. of Life Sci and Technol., Titech
Keyword: Immune-Mediated Neuronal Cell Death, LINE1, L1, Eomes+ Th cells, Cell Cycle
Neurodegeneration is a pathological process of cell autonomous/non-cell autonomous neuronal loss and subsequent collapse of neural networks. Although proteinopathy has been exclusively underscored in association with neurodegeneration, the true culprit of neuronal cell death is still under debate. Recently, glial cells were attracted attention as an intrinsic component for non-cell autonomous neurodegeneration, where enhanced expression of MHC II molecule and upregulation of IFN signature in disease-associated microglia (DAM) implies a possible pathogenic involvement of dysregulated immune responses in a mouse model of AD. We have been studying the pathogenic mechanism of neurodegeneration observed in a progressive type of multiple sclerosis (MS): secondary progressive MS (SPMS). We have identified that a cytotoxic helper T cell subset expressing Eomesodermin (Eomes+ Th cells) which predominantly accumulated in the CNS during experimental autoimmune encephalomyelitis (EAE) and SPMS, causes neuronal cell death via secretion of neurotoxic granzyme B. Furthermore, we identified that ORF1 protein encoded by retrotransposon long interspersed nuclear element-1 (LINE-1, L1) gene is ectopically expressed in neurons of diseased mice and activates Eomes+ Th cells to secrete granzyme B via MHC class II-dependent manner. Approximately half of the human genome is composed of retrotransposable elements (RE) and a half million copies of L1 genes occupy one-third of such RE. Among them, 80-100 and 3000 copies of L1 genes are retrotransposable in human and mouse respectively, and dysregulated L1 activation causes neurodevelopmental and neurodegenerative diseases. In this study, we demonstrate that Eomes+ Th cells accumulate in the CNS of authentic mouse models of the neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and Alzheimer’s disease (AD), and secrete neurotoxic granzyme B after exposure to ORF1 antigen. Furthermore, we demonstrated that cell cycle-dependent derepression of neuronal L1 is involved in neurodegeneration in animal models of ALS/AD. As aberrant cell cycle progression is a typical feature of neurodegeneration, our data suggest that CNS accumulation of Eomes+ Th cells and the multimodal derepression of L1 gene leading to ectopic supply of L1-derived antigen(s) under chronic inflammation may enhance propagation of immune mediated-neuronal cell death and provide a previously unappreciated pathogenic mechanism of neurodegenerative diseases. | |
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