一般口演（若手道場）

一般口演（若手道場）若手道場　グリアと疾患 Wakate Dojo: Glia and Disorders 座長：池中建介（大阪大学大学院医学系研究科　神経内科学講座）・東田千尋（富山大学和漢医薬学総合研究所）

2022年7月1日　15:00～15:15　沖縄コンベンションセンター会議場B2　第5会場 2WD05a2-01 オリゴデンドロサイト特異的な変異型TDP-43過剰発現はマウスの運動機能障害を惹起する Oligodendrocyte-specific overexpression of mutant TDP-43 induces motor dysfunction in mice 堀内麻衣(1)、渡邊征爾(1)、山中宏二(1) 1. 名古屋大学環境医学研究所 Mai Horiuchi(1), Seiji Watanabe(1), Koji Yamanaka(1) 1. Research Institute of Environmental Medicine, Nagoya University, Aichi, Japan Keyword: Amyotrophic lateral sclerosis, TDP-43, Oligodendrocyte 筋萎縮性側索硬化症(ALS)は上位および下位の運動神経が選択的に障害される進行性の神経変性疾患であり、一部は遺伝性に発症する。 TAR-DNA結合タンパク質43(TDP-43) はALSの原因遺伝子として同定されており、翻訳やスプライシングといった多面的なRNA代謝に関わっている。TDP-43は通常、核に局在するが、ALSおよび前頭側頭型認知症の一部では細胞質に移行して凝集体を形成する。この病理像は神経細胞およびオリゴデンドロサイトで観察され、これらの細胞群の異常が示唆される。神経細胞特異的にTDP-43を過剰発現させたマウスでは運動神経細胞死が生じることが報告されており、gain of toxicityの機序による細胞毒性の獲得が示唆される。一方で、オリゴデンドロサイトにTDP-43を過剰発現させた場合の毒性については未だ評価されていない。我々は、オリゴデンドロサイトにおける変異型TDP-43過剰発現の影響を解析するため、相同組換え法を利用してTDP-43をCre依存的に過剰発現するトランスジェニックマウスを作成した(cTg-TDP-43^M337V)。CAGプロモーターの下流にALS関連変異であるhumanTDP-43^M337VのcDNA配列を組み込んだ発現カセットを、Rosa26遺伝子座に挿入した。このマウスとMbp-Creマウスを交配して得られた仔マウスにおいて、Cre依存的な変異型TDP-43の発現変化を脳および脊髄組織で確認した。Cre陽性のマウスは加齢に伴って全身性の振戦および低体重傾向を示した。神経症状を認める12ヶ月齢の脊髄では、白質の髄鞘淡明化とミエリン塩基性蛋白の発現低下傾向を認めた。さらにミクログリアおよびアストロサイトが活性化しており、脊髄白質において活性化ミクログリアによるオリゴデンドロサイトの貪食を示唆する像がみられた。これらの結果より、変異型TDP-43の過剰発現がオリゴデンドロサイトの生理的機能を障害し、グリア細胞がオリゴデンドロサイトを除去することによって運動機能障害を惹起することが示唆された。オリゴデンドロサイト異常の詳細なメカニズムを解明するため、初代培養法などの手法を用いて検討を続けている。		2022年7月1日　15:15～15:30　沖縄コンベンションセンター会議場B2　第5会場 2WD05a2-02 MARK2によるグリア細胞の免疫応答調節とその神経変性に対する役割 MARK2 modulates glial immune responses and neurodegeneration 福地葵(1)、中嶋翔(1)、斎藤太郎(1,2)、淺田明子(1,2)、安藤香奈絵(1,2) 1. 東京都立大学大学院理学研究科生命科学専攻神経分子機能研究室、2. 東京都立大学理学部生命科学科 Aoi Fukuchi(1), Sho Nakajima(1), Taro Saito(1,2), Akiko Asada(1,2), Kanae Ando(1,2) 1. Dept Bio Sci, Grad Sch Sci, Tokyo Metropolitan Univ, 2. Dept Bio Sci, Sch Sci, Tokyo Metropolitan Univ Keyword: glial cell, immune response, MARK2, neurodegeneration Microglia are resident immune cells in the brain and protect neurons from external substances, stress, and infection. On the other hand, their chronic or excessive responses lead to neuronal damage. Microglia are activated in neurodegenerative diseases and trigger neuroinflammation, which has been suggested to facilitate neurodegeneration. Activated microglia release pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) and influence the surrounding brain tissue. However, it is not fully understood how microglial activation is regulated under disease conditions. Microtubule affinity-regulating kinase 2 (MARK2) belongs to an evolutionary conserved Ser/Thr kinase family, Par-1/MARK. Recently, MARK2 was reported to function in immune cells. Here we report that MARK2 suppresses microglial activation in response to pro-inflammatory stimuli. We found that MARK2 knockdown in the immortalized murine microglial cell line BV2 cells promotes the release of the pro-inflammatory cytokine IL-6 after the lipopolysaccharide (LPS) treatment and Imiquimod. In contrast, MARK2 did not affect IL-6 release after stimulation by a murine STING ligand DMXAA or a specific agonist of retinoic-acid-inducible protein 1, 3p-hpRNA. Since LPS and Imiquimod activate Toll-like receptor (TLR) 4 and TLR7, these results suggest that MARK2 negatively regulates these signaling pathways. We also found that LPS stimulation suppressed the kinase activity of MARK2. Next, we investigated the role of MARK homolog Par-1 in glial cells in neurodegeneration in a Drosophila model of tau toxicity. Tau expression in the retina causes photoreceptor degeneration as well as upregulation of toxic cytokines. Interestingly, knocking down Par-1 specifically in glial cells in the retina enhanced tau-induced neurodegeneration. These results suggest that Par-1 in glial cells regulates its activity to modify tau-induced photoreceptor degeneration. Our results suggest that MARK2 modulates glial inflammatory responses and that its inactivation may cause the overactivation of microglia. Disruption of MARK2 activity in neurodegenerative conditions may facilitate neuronal damage in disease brains.

2022年7月1日　15:30～15:45　沖縄コンベンションセンター会議場B2　第5会場 2WD05a2-03 内在性DNAを介したミクログリア活性化によるレット症候群発症の可能性 Possible involvement of endogenous DNA-induced microglial activation in the pathogenesis of Rett syndrome 中嶋秀行(1)、中島欽一(1) 1. 九州大学 Hideyuki Nakashima(1), Kinichi Nakashima(1) 1. Kyushu university Keyword: RTT, MeCP2, microglia, TLR9 Rett syndrome (RTT) is a severe progressive neurodevelopmental disorder in females, mainly caused by mutations in the X-linked gene encoding methyl-CpG binding protein 2 (MeCP2). Substantial evidence has shown that morphological and functional abnormalities of neurons are involved in RTT pathogenesis, therefore, it has been considered that symptoms of RTT are attributed to neuron-intrinsic dysfunction in the patients. However, increasing evidence has suggested that glial abnormalities associate with the pathogenesis of RTT, e.g., activation of microglia, brain-resident immune cells resembling macrophage, has been observed in MeCP2 knock-out (KO) RTT model mice, whereas the underlying mechanisms still remains unknown. We have previously shown that the expression of retrotransposon LINE1 (L1) and the transposition of its reverse transcript (cDNA) into the genome are increased in MeCP2-KO mouse brains. Furthermore, taken together with our recent finding that endogenous DNAs activate hippocampal microglia via DNA-recognizing Toll-like receptor 9 (TLR9), we have hypothesized that L1cDNA-induced microglia activation mediated by TLR9 is involved in RTT pathogenesis. Here, we report that aberrant microglial activation and RTT phenotypes in MeCP2 deficient mice are ameliorated in TLR9-heterozygous background. We also found that abnormal neuronal morphology observed in MeCP2-KO mouse brain was improved in the TLR9-heterozygous background. Although we have not proved that the microglia-activating endogenous DNAs are the L1cDNAs, these results suggest that as yet unidentified endogenous DNAs activate microglia through TLR9 in MeCP2 deficient brain and pertain to the RTT pathogenesis. Therefore, it is conceivable that endogenous DNA-TLR9-microglial activation axis can be a potential therapeutic target of RTT.		2022年7月1日　15:45～16:00　沖縄コンベンションセンター会議場B2　第5会場 2WD05a2-04 タウはPQBP1-cGAS-STING経路を介してミクログリアの炎症応答を促進する Tau activates microglia via the PQBP1-cGAS-STING pathway to promote brain inflammation 金美花(1)、塩飽裕紀(3)、田中ひかり(1)、吉岡優希(1)、Jin Xiaocen(1)、近藤叶(1)、藤田慶大(1)、本間秀典(1)、岡澤均(1,2) 1. 東京医科歯科大学難治疾患研究所神経病理学分野、2. 脳統合機能研究センター、3. 東京医科歯科大学　精神行動医科学分野 MEIHUA JIN(1), Hiroki Shiwaku(3), Hikari Tanaka(1), Yuki Yoshioka(1), Xiaocen Jin(1), Kanoh Kondo(1), Kyota Fujita(1), Hidenori Homma(1), Hitoshi Okazawa(1,2) 1. Department of Neuropathology, Medical Research Institute,Tokyo Medical and Dental University, 2. Center for Brain Integration Research, 3. Department of Psychiatry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University Keyword: PQBP1, Tau, Microglia, inflammation Brain inflammation generally accompanies and accelerates neurodegeneration. PQBP1 has been previously shown to sense and bind HIV DNA and trigger an immune pathway known as the cGAS-STING pathway to initiate an inflammatory response. While PQBP1 has also been shown to interact with dysfunctional proteins such as those implicated in the neurodegenerative disorder Huntington’s disease, the specific role of PQBP1 in neurodegenerative inflammatory responses was unclear. In this study, we report a microglial mechanism in which polyglutamine binding protein 1 (PQBP1) senses extrinsic tau 3R/4R proteins by direct interaction and triggers an innate immune response by activating a cyclic GMP-AMP synthase (cGAS)-Stimulator of interferon genes (STING) pathway. Tamoxifen-inducible and microglia-specific depletion of PQBP1 in primary culture in vitro and mouse brain in vivo shows that PQBP1 is essential for sensing-tau to induce nuclear translocation of nuclear factor kB (NFkB), NFkB-dependent transcription of inflammation genes, brain inflammation in vivo, and eventually mouse cognitive impairment. Collectively, PQBP1 is an intracellular receptor in the cGAS-STING pathway not only for cDNA of human immunodeficiency virus (HIV) but also for the transmissible neurodegenerative disease protein tau. This research sheds new light on the role of PQBP1 in the detection of dysfunctional proteins associated with neurodegenerative disorders. It also clarifies a mechanism of inflammation in the brain that functions in both viral infection and neurodegenerative disease. Unexpectedly, intracellular dynamics of tau protein such as direct incorporation into rough ER was also homologous to that of corona viruses including SARS-CoV-2 of COVID-19. Moreover, results obtained in this study have provided us with a further perspective that tau-propagation-induced pathologies of tauopathy are based not only on prionoid propagation among neurons, which possesses a kind of speciﬁcity in propagation pattern, but also on substance diffusion between neurons and microglia, which by itself does not deﬁne a speciﬁcity for expansion pattern in the brain.