一般口演
シナプス可塑性 / 翻訳語修飾とタンパク分解など
Synaptic Plasticity / Posttranslational Modulation and Proteolysis
座長：山本 亘彦（大阪大学） |
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| 2022年7月2日 10:00～10:15 沖縄コンベンションセンター 会議場B2 第5会場
3O05m2-01
Plasticity of synaptic fidelity in the intact brain
*Dmitri Rusakov(1)
1. UCL Queen Square Institute of Neurology, London, UK
Keyword: Synaptic plasticity, Multiplexed glutamate and calcium imaging in vivo, LTP, Release probability
Presynaptic mechanisms that control release of neurotransmitters are fundamental to our understanding of how the brain works, in health and disease. The recent emergence of genetically encoded optical indicators for major neurotransmitters has triggered important breakthroughs, both methodological and conceptual, in this quest. We have advanced a multiplexed imaging technique to monitor glutamate release and, simultaneously, presynaptic Ca2+ dynamics at small excitatory synapses in situ. This helped us to find that glutamate release efficacy, but not its short-term plasticity, varies with the fluctuations in presynaptic resting Ca2+ and in spike-evoked Ca2+ entry. We combined this approach with targeted viral transduction of optical indicators in vivo and employed a sensory stimulation paradigm to monitor dynamic changes of synaptic fidelity at individual synaptic connections. Our data suggest that a whisker-stimulation induced long-term potentiation (LTP) of transmission in the thalamocortical circuit of the rat involves increased synaptic release probability while moderating afferent input to the barrel cortex. High-resolution multiplexed imaging unveils significant extrasynaptic escape of glutamate in this circuitry, which is further exacerbated upon the induction of LTP. We have also found that the latter involves local withdrawal of perisynaptic astroglial processes enriched in high-affinity glutamate transporters. These observations introduce a novel form of synaptic plasticity in the intact brain and challenge the traditional view on excitatory circuits as a 'wired' network of one-to-one connections. | | 2022年7月2日 10:15～10:30 沖縄コンベンションセンター 会議場B2 第5会場
3O05m2-02
シナプス活動依存的な樹状突起スパインへの滑面小胞体伸展は記憶固定化に寄与する
Activity-triggered extension of endoplasmic reticulum into dendritic spines as a synaptic basis of memory consolidation
*上田(石原) 奈津実(1,2)、深澤 有吾(3)、小坂 優介(1)、水上 真智(1)、高雄 啓三(4)、見学 美根子(5)、宮川 剛(6)、井ノ口 馨(4)、尾藤 晴彦(7)、木下 専(1)
1. 名古屋大学大学院理学研究科、2. JSTさきがけ、3. 福井大学学術研究院医学系部門、4. 富山大学学術研究部医学系、5. 京都大学高等研究院iCeMS、6. 藤田医科大学 総合医科学研究所、7. 東京大学大学院医学系研究科
*Natsumi Ageta-Ishihara(1,2), Yugo Fukazawa(3), Yusuke Kosaka(1), Masato Mizukami(1), Keizo Takao(4), Mineko Kengaku(5), Tsuyoshi Miyakawa(6), Kaoru Inokuchi(4), Haruhiko Bito(7), Makoto Kinoshita(1)
1. Grad Sch Sci, Nagoya Univ, Nagoya, Japan, 2. JST, PRESTO, Saitama, Japan, 3. Sch Med, Univ of Fukui, Fukui, Japan, 4. Fac Med, Univ of Toyama, Toyama, Japan, 5. KUIAS-iCeMS, Kyoto Univ, Kyoto, Japan, 6. ICMS, Fujita Health Univ, Toyoake, Japan, 7. Grad Sch Med, Univ of Tokyo, Tokyo, Japan
Keyword: memory consolidation
Transient memories are converted to persistent memories through protein synthesis-dependent consolidation processes at synapse and circuit/systems levels. Synaptic consolidation parallels electrophysiological transition from early- to late-phase long-term potentiation (E-/L-LTP) of synaptic transmission. While glutamate signaling upregulations coupled with dendritic spine enlargement are common underpinnings of E-LTP and L-LTP, synaptic mechanisms conferring persistence on L-LTP remain unclear. Here we show that strong synaptic activities trigger extension of smooth endoplasmic reticulum (sER) from dendritic shaft into enlarged spines, which facilitates Ca2+ responses for sustained synaptic activities: Electrophysiological stimuli that induce L-LTP in the perforant path-hippocampal dentate gyrus synapses elicit remodeling of F-actin and a septin subunit SEPT3. Sept3-/- mice fail to retain spatial contextual memory, whose hippocampal synapses are morphologically normal except for a scarcity of sER-containing spines in the responsible DG granule cells. Chemical stimuli that induce L-LTP in cultured granule cells trigger fast spine enlargement, and slow sER extension that depends on Ca2+-activated association between myosin motor MYO5A and SEPT3. Perturbations of MYO5A or SEPT3 prevent activity-triggered sER extension into enlarged spines, attenuating spontaneous firing of granule cells. The amplitude and duration of glutamate-induced Ca2+ transient are higher in spines with sERs than in those without, which is abolished upon thapsigargin-mediated inhibition of Ca2+ storage/release by sER. These findings indicate that sER extension serves as a positive feedback mechanism underlying synaptic consolidation and memory persistence. | | 2022年7月2日 10:30～10:45 沖縄コンベンションセンター 会議場B2 第5会場
3O05m2-03
神経・筋恒常性に必須の新たな細胞内タンパク質分解経路の同定
Identification of a novel protein-uptake pathway in lysosomes required for neuromuscular homeostasis
*藤原 悠紀(1,2)、Viorica Raluca Contu(1)、株田 千華(1)、小川 恵(1)、宮城 美月(3)、酒井 了平(1)、長谷 勝徳(1)、鈴木 マリ(4)、小山 郁子(5)、井上 道雄(1)、大矢 寧(6)、井上 由紀子(1)、川野 竜司(3)、井上 高良(1)、高橋 良輔(7)、西野 一三(1)、和田 圭司(1)、野口 悟(1)、株田 智弘(1)
1. 国立精神・神経医療研究センター 神経研究所、2. 大阪大学 大学院 連合小児発達学研究科、3. 東京農工大学大学院 工学府、4. 東京都医学総合研究所 疾患制御研究分野、5. 東京大学大学院 医学系研究科、6. 国立精神・神経医療研究センター病院 脳神経内科、7. 京都大学大学院 医学研究科
*Yuuki Fujiwara(1,2), Viorica Raluca Contu(1), Chihana Kabuta(1), Megumu Ogawa(1), Mitsuki Miyagi(3), Ryohei Sakai(1), Katsunori Hase(1), Mari Suzuki(4), Ikuko Koyama-Honda(5), Michio Inoue(1), Yasushi Ohya(6), Yukiko Inoue(1), Ryuji Kawano(3), Takayoshi Inoue(1), Ryosuke Takahashi(7), Ichizo Nishino(1), Keiji Wada(1), Satoru Noguchi(1), Tomohiro Kabuta(1)
1. National Institute of Neuroscience, National Center of Neurology and Psychiatry, 2. United Graduate School of Child Development, Osaka University, 3. Faculty of Engineering, Tokyo University of Agriculture and Technology, 4. Department of Sensory and Motor Systems, Tokyo Metropolitan Institute of Medical Science, 5. Graduate School of Medicine, The University of Tokyo, 6. Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, 7. Graduate School of Medicine, Kyoto University
Keyword: lysosome/autophagy, proteolysis/protein degradation, neuropathy/myopathy, direct-uptake-via/through-membrane-protein (DUMP)
Regulated degradation of cellular components plays an essential role in homeostasis. Lysosomes are largest sites for degradation of virtually all kinds of intracellular macromolecules. Accumulating evidences point out the importance of lysosomal degradation of cellular proteins: Dysfunctions in multiple pathways to deliver cytosolic substrates into lysosomes are related to various diseases, including neurodegenerative diseases and myopathies. However, much of the effort at understanding such pathways has been devoted to studies on "macroautophagy", which entails vast and dynamic rearrangement of membrane structure, and knowledge on other delivery systems and functions of lysosomes per se remains scant.
Here, we show that cytosolic proteins are directly imported into lysosomes in an ATP-dependent manner by a mechanism distinct from any known pathways and degraded. We term this novel pathway as "direct-uptake-via/through-membrane-protein (DUMP)". We find that a lysosomal membrane protein, SIDT2, which was previously reported as a putative nucleic acid transporter, is involved in the translocation of substrate proteins in this system. Gain- and loss-of-function analyses reveal that SIDT2 contributes conspicuously to the lysosomal degradation of a wide range of cytosolic proteins in cells at the constitutive level.
Furthermore, we identified a patient of familial neuropathy and myopathy with rimmed vacuoles, harboring a dominant-negative mutation in SIDT2. Sidt2 knockout mice recapitulated typical features of rimmed vacuolar myopathy/neuropathy, which closely resembles observations seen in the patient, including accumulation of cytoplasmic inclusions.
These results reveal a previously unknown pathway of proteolysis in lysosomes and highlight the importance of noncanonical types of autophagy in physiology and pathophysiology of human. | | 2022年7月2日 10:45～11:00 沖縄コンベンションセンター 会議場B2 第5会場
3O05m2-04
USP10はストレス顆粒の除去を促進することによりTDP-43の異常な細胞質凝集を抑制する
USP10 inhibits aberrant cytoplasmic aggregation of TDP-43 by promoting stress granule clearance
*高橋 雅彦(1)、北浦 弘樹(2)、柿田 明美(2)、垣花 太一(1)、葛城 美徳(1)、小野寺 理(3)、藤井 雅寛(1)
1. 新潟大学大学院医歯学総合研究科ウイルス学分野、2. 新潟大学脳研究所病理学分野、3. 新潟大学脳研究所神経内科学分野
*Masahiko Takahashi(1), Hiroki Kitaura(2), Akiyoshi Kakita(2), Taichi Kakihana(1), Yoshinori Katsuragi(1), Osamu Onodera(3), Masahiro Fujii(1)
1. Division of Virology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan, 2. Department of Pathology, Brain Research Institute, Niigata University, Niigata, Japan, 3. Department of Neurology, Brain Research Institute, Niigata University, Niigata, Japan
Keyword: TAR DNA-binding protein 43 (TDP-43), Ubiquitin-specific protease 10 (USP10), Stress granule, Aggresome
Background
Amyotrophic lateral sclerosis (ALS) is a rapidly progressive, lethal motor neuron disease. Intracytoplasmic inclusions of TAR DNA-binding protein 43 (TDP-43) in neurons in the spinal cord and brain is a hallmark pathology of ALS. Under various stress conditions, TDP-43 localizes to stress granules (SGs), which are cytoplasmic aggregates containing many RNA-binding proteins. Intriguingly, accumulating evidence suggests that delayed clearance of SGs is associated with pathological TDP-43 aggregates in ALS. However, how the clearance of SGs is regulated remains to be fully elucidated. We have shown that ubiquitin-specific protease 10 (USP10) regulates SG formation and protein aggregation in cultured cells. Here, we investigated how USP10 regulates the pathological aggregation of TDP-43 in SGs.
Result
Treatment of cultured neuronal and non-neuronal cells with proteasome inhibitor (PI) induced sequentially TDP-43-positive SGs and TDP-43-positive aggresomes, but knockdown of USP10 delayed the clearance of TDP-43-positive SGs and reduced the formation of TDP-43-positive aggresomes, instead increasing the amount of insoluble cytoplasmic TDP-35, a C-terminal fragment of TDP-43 lacking the N-terminal region. TDP-35 interacted with USP10, but none of the TDP-35 mutants with reduced RNA-binding activity interacted with USP10, resulting in reduced localization to SGs and aggresomes and formation of abnormal USP10-negative TDP-35 aggregates. Furthermore, most cytoplasmic TDP-43/TDP-35 aggregates in neurons from ALS patients did not co-localize with USP10.
Conclusion
These results suggest that USP10 inhibits aberrant aggregation of TDP-43/TDP-35 in the cytoplasm of neuronal cells by promoting the clearance of TDP-43/TDP-35-positive SGs. In addition, these results suggest that TDP-35 may be involved in the abnormal aggregation of TDP-43. | |
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