一般口演
神経細胞死とアポトーシス / 軸索と樹状突起の伸長と回路形成など
Neuronal Death and Apoptosis / Axon/Dendrite Growth and Circuit Formation
座長：桐生 寿美子（名古屋大学医学系研究科） |
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| 2022年7月1日 14:00～14:15 ラグナガーデンホテル 羽衣：東 第8会場
2O08a1-01
ニューロン間およびニューロン-グリア間の相互作用を介した軸索変性機序の解明
Analysis of the mechanism underlying axonal degeneration via neuron-neuron and neuron-glial interactions
*杉江 淳(1)
1. 新潟大学脳研究所
*Atsushi Sugie(1)
1. Niigata University
Keyword: axonal degeneration, Drosophila, tripartite synapse
Synaptic loss is an early symptom in several neurodegenerative diseases. It has a strong pathological correlation with cognitive decline. In addition to synaptic loss, axonal degeneration is also an early event in neurodegenerative diseases. It ultimately leads to degeneration of the cell body through a retrograde degenerative process called 'dying back pathology'. We attempted to elucidate the pathological mechanism with changes in synaptic connection and axonal degeneration that underlie early stages in neurodegenerative diseases. For this purpose, we use Drosophila photoreceptor neurons as a model and developed a system that causes synaptic loss and axonal degeneration when flies are exposed to constant but excessive physiological stimuli. In this system, we selected a subset of the photoreceptors, R7s, which project axons precisely into the specific layer of the second optic ganglion, medulla, and have a highly regular distribution. During the axonal degeneration, the terminal of individual R7 axon is easy to identify the random loss. In this study, we found that the synaptic connections between R7s and the postsynaptic partners, Dm8s, were first lost, followed by axonal degeneration. Importantly, axonal degeneration of R7 was not associated with retinal cell body degeneration or apoptosis, reproducing the characteristics of human neurodegenerative diseases. Our observations also indicate that neurotransmission to the postsynaptic partner of R7 is required during degeneration and imply that the postsynaptic cell returns unknown signal to the photoreceptor cell to maintain axonal structure. We would like to define the early changes that happen within neurons at the time point in which their resilience capacity is overcome. | | 2022年7月1日 14:15～14:30 ラグナガーデンホテル 羽衣：東 第8会場
2O08a1-02
コンドロイチン硫酸結合ペプチドはdystrophic endballを解消し脊髄損傷に伴う運動障害を改善する
Chondroitin sulfate-binding peptide rescues the dystrophic endballs and improves spinal cord injury-induced dysmotility
*尾崎 智也(1,2)、坂元 一真(1)、鈴木 佑治(1)、門松 健治(1)
1. 名古屋大学大学院医学系研究科 分子生物学、2. 名古屋市立大学大学院医学研究科 脳神経科学研究所 神経毒性学
*Tomoya Ozaki(1,2), Kazuma Sakamoto(1), Yuji Suzuki(1), Kenji Kadomatsu(1)
1. Molecular Biology, Grad Sch Med, Nagoya Univ, Nagoya, Japan, 2. Neurotoxicology, Inst Brain Sci, Grad Sch Med Sci, Nagoya City Univ, Nagoya, Japan
Keyword: axon injury, axon regeneration, chondroitin sulfate, dystrophic endball
Spinal cord injury (SCI) results in the damage in neural circuits that cause long-term locomotor disability. There is still no effective treatment for SCI. This problem is because of the lack of a solution to a powerful inhibitor for axon regeneration. Chondroitin sulfate proteoglycans (CSPGs) accumulate abnormally in the damaged area after SCI. The CS on the CSPGs strongly inhibits the re-growth of nerve axons. The CS induces abnormal round morphology in the injured axon tips. This pathology of damaged axons was discovered nearly 100 years ago and is called dystrophic endball. Recently, as part of the molecular mechanism of dystrophic endball formation, it was found that CS triggers autophagy interruption in damaged axon terminals, and the involvement of cortactin as a new substrate for the CS receptor, RPTPσ (receptor-type protein tyrosine phosphatase), was reported. It is also a widely accepted fact that targeting CS promotes axonal regeneration and functional recovery. However, the strategies have not been fully examined and it has not led to the practical therapeutics. This study aims to evaluate whether an existing drug, chondroitin sulfate-binding peptide can be a therapeutic agent for spinal cord injury. First, we examined the rescue effect of CSBP to in vitro dystrophic endballs using a culture model that mimics the CS accumulation at the site of spinal cord injury. As a result, axons with dystrophic endball and incapable of re-growth by CS resumed elongation after CSBP treatment and were able to pass through the CS barrier. In addition, CSBP eliminated autophagosome accumulation inside the dystrophic endball. Next, we administered 1 mg/kg of CSBP through the tail vein to mice suffering from hindlimb motor dysfunction by spinal cord injury surgery. Then, we evaluated whether CSBP induced recovery of hindlimb motor function. CSBP administrations have improved the hindlimb motor function. This study has revealed that the existing drug CSBP cancels the CS inhibitory effect on axonal re-growth. In addition, administration of CSBP relieved the hindlimb motor dysfunction in SCI mice. Our results have suggested an effective therapeutic agent for spinal cord injury and also showed a possibility of drug repositioning. Moreover, it is also expected to have therapeutic effects on brain injury. | | 2022年7月1日 14:30～14:45 ラグナガーデンホテル 羽衣：東 第8会場
2O08a1-03
齧歯類とヒトの成長軸索における複数のJNK依存的GAP-43リン酸化サイトの同定
JNK-dependent phosphorylation sites of GAP-43 in the growing axons of rodents and human
*岡田 正康(1,2,3)、河嵜 麻実(3)、 金子 奈穂子(4)、野住 素広(3)、山崎 博幸(5)、福角 勇人(6)、金村 米博(6)、澤本 和延(4)、藤井 幸彦(2)、五十嵐 道弘(3)
1. 新潟大学医歯学総合病院、2. 新潟大学脳研究所脳神経外科分野、3. 新潟大学医歯学系神経生化学分野、4. 名古屋市立大学大学院医学研究科脳神経科学研究所 神経発達・再生医学分野、5. 群馬医療福祉大学社会福祉学部、6. 大阪医療センター 臨床研究センター 先進医療研究開発部
*Masayasu Okada(1,2,3), Asami Kawasaki(3), Naoko Kaneko(4), Motohiro Nozumi(3), Hiroyuki Yamazaki(5), Hayato Fukusumi(6), Yonehiro Kanemura(6), Kazunobu Sawamoto(4), Yukihiko Fujii(2), Michihiro Igarashi(3)
1. Dept Neurosurg, Niigata Univ Med and Dent Hospital, Niigata, Japan, 2. Dept Neurosurg, BRI, Niigata Univ, Niigata, Japan, 3. Dept Neurochem, Med & Dent Sci, Niigata Univ, Niigata, Japan, 4. Dept Dev & Reg Biol, Inst of Br Sci, Nagoya City Univ Grad Sch of Med Sci, Nagoya, Japan, 5. Faculty of Social Welfare, Gunma Univ of Health and Welfare, Maebashi, Japan, 6. Dept of Biomed Res and Innov, Inst for Clin Res, Natl Hosp Org Osaka Natl Hosp, Osaka, Japan
Keyword: Neural development, GAP-43, Phosphorylation
Growth-associated protein-43 kDa (GAP-43) was identified as a protein related to axon growth and regeneration more than 45 years ago, however, its function is not yet clearly understood. So far, we performed phosphoproteomics of the neonatal rodent growth cone. As a result, we have succeeded in characterizing our research on serine 96 (S96) and threonine 172 (T172) of GAP- 43 (iScience 2018; Molecular Brain 2021). Furthermore, phosphoproteomics of mouse brain GAP-43 on postnatal day 8 (P8) and marmoset P1 brain revealed that S142, in addition to T172, is a phosphorylation site of GAP-43 existing in both rodents and human (Okada et al., in revision). We produced phospho-specific antibodies of GAP-43 S96 (pS96), T172 (pT172), S142 (pS142), and obtained the following results: (1) These three antibodies were more specific markers for rodent nerve growth and axon regeneration than GAP-43 antibody itself; (2) The kinase phosphorylating these three residues commonly was c-jun N-terminal kinase (JNK), which is currently believed to be essential for normal brain development; (3) pT172 and pS142 were detected using phosphoproteomics in neonatal common marmoset brains, and immunohistochemical studies confirmed the presence of pT172 in in vivogrowing axons; (4) Differentiated neurons derived from human iPS cells (hiPSC) had pT172- and pS142-positive growing axons and growth cones. Taken together, pS96, pT172, and pS142 are tightly associated with axonal growth, and common JNK-regulated sites of GAP-43. In addition, pT172 and pS142 are concluded to be markers for human axon growth, suggesting the molecular probes, which we established here. The neurons differentiated from hiPSC are available to the basic studies on human neurons, but the identification of molecules involved in axonal growth or synaptogenesis, related to human events, is the issue to be solved. pT172 and pS142 Antibodies are useful tools for elucidating the mechanism of human axonal growth. | | 2022年7月1日 14:45～15:00 ラグナガーデンホテル 羽衣：東 第8会場
2O08a1-04
Chromatin regulation of human cortical development by LSD1
*Muralidharan Bhavana(1)、D'Souza Leora(1)、Kalia Kishan(1)
*Bhavana Muralidharan(1), Leora D'Souza(1), Kishan Kalia(1)
1. Institute for Stem Cell Science and Regenerative Medicine
Keyword: Epigenetic, Cortical development, Progenitor, Neuron
The cerebral cortex is the seat of all higher order functions in the brain namely, sensory perception, decision-making, language, learning and memory.
Chromatin and epigenetic regulations play a critical role in cerebral cortical development. Studying the chromatin regulatory mechanisms is important to our understanding of the fundamental process of building the brain and it is mutations in the very same networks, which lead to a range of neurodevelopmental disorders. LSD1 is a histone lysine-specific demethylase which functions in the demethylation of mono- and di- methylated H3K4 and H3K9. Its role in human corticogensis is unexplored. We have performed LSD1 ChIP-seq in human neural stem cells to ascertain its genome -wide downstream targets. Our study has revealed that LSD1 predominantly binds to promoters and intergenic regions in the human cerebral cortical stem cell genome. The genes regulated by LSD1 are crucial for forebrain development, axon guidance, synapse organization and WNT signalling pathway. We further compared our dataset with published dataset from human fetal cortex single cell transcriptome analysis to delineate the specific targets along the span of neuronal differentiation from apical progenitors to basal progenitors to newly post mitotic neurons. Ventricular or apical radial glia are bipolar and are contacting the apical surface. These divide to give rise to the outer radial glia which migrate to the outer SVZ thereby contacting the pial surface. Our analysis reveals that a large number of LSD1 target genes are genes expressed in apical radial glia and outer radial glia thereby suggesting its role in regulating the progenitor. Further analysis is underway to functionally validate these targets genes by performing genome-wide RNA-seq upon LSD1 inhibition. Thus this study will augment our fundamental understanding of how the genome is deployed to build the human cerebral cortex. | |
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