若手道場

若手道場　グループＢ Wakate Dojo group B

2020/9/11　13:30～13:45　オンデマンドA-2 WD5 Diosgeninがアルツハイマー病モデルマウスの脳内において軸索を再伸長させる分子メカニズムの解明 Clarification of the mechanisms for diosgenin-induced accurate axonal regrowth in the brain of a mouse model of Alzheimer's disease 楊熙蒙¹、東田千尋¹ 1. 富山大学和漢医薬学総合研究所神経機能学領域 Ximeng Yang¹, Chihiro Tohda¹ 1. Section of Neuromedical Science, Institute of Natural Medicine, University of Toyama Alzheimer's disease (AD) is a progressing neurodegenerative disorder developed by deposition of amyloid plaques in the brain. We previously found that diosgenin, a constituent of Dioscorea Rhizoma, improved memory function in a mouse model of AD, 5XFAD. Besides, importantly, we firstly clarified that diosgenin promoted axonal regrowth in 5XFAD mice brains (in vivo). Therefore, in the present study, we aimed to clarify molecular mechanisms for accurate pathfinding of degenerated axons in AD brains. At first, axonal regrowth effect of diosgenin was investigated in the circuits contributing memory formation; the hippocampus to the prefrontal cortex in 5XFAD mice brain. Retrograde tracing revealed that axonal projections from the hippocampus to the prefrontal cortex were significantly decreased in 5XFAD compared with wild-type mice. However, 14-day administration of diosgenin to 5XFAD mice significantly promoted axonal regrowth in this circuit. After that, naïve neurons and axon-regrew neurons in the brain slices were separately captured by laser microdissection to serve DNA microarray. We focused on the gene, its expression was the most elevated in axon-regrew neurons, and this gene was overexpressed in cultured neurons and in the hippocampus of 5XFAD mice brains. As results, axonal growth was significantly promoted in cultured neurons and memory function was significantly recovered in 5XFAD mice by overexpression of this gene (the name is closed currently). Our study suggests for the first time that degenerated axons in AD brains have capacities to regrow toward their native projecting area. Furthermore, there should be molecular mechanisms for controlling accurate pathfinding of injured axons in adult brains, which proposes a novel therapeutic strategy for AD treatment.		2020/9/11　13:50～14:05　オンデマンドA-2 WD6 アンモニアはアストロサイトにおいてアミロイドβ42の産生を促進する。 Ammonia promotes amyloid beta42 production in astrocytes. 小松彩夏^1,2、岸川咲吏²、伊藤元貴²、飯田和泉²、那須優介²、照沼美穂² 1. 新潟大学大学院医歯学総合研究科口腔生命福祉学専攻、2. 新潟大学大学院医歯学総合研究科口腔生化学分野 Ayaka Komatsu^1,2, Sari Kishikawa², Genki Ito², Izumi Iida², Yusuke Nasu², Miho Terunuma² 1. Div of Oral Health and Welfare, Grad Sch of Med and Dent Sci, Niigata Univ, 2. Div of Oral Biochemistry, Grad Sch of Med and Dent Sci, Niigata Univ Ammonia has long been known as a neurotoxin in the brain, and astrocytes, the most abundant non-neuronal cells in the central nervous system, are found to be involved in the clearance of ammonia. Interestingly, high levels of ammonia have been detected in Alzheimer's disease (AD) patients, but their pathophysiological association is still unclear. To study if ammonia induces the expression of AD pathology, we examined two major AD-related molecules, beta-amyloid (Aβ) and amyloid precursor protein (APP) in cultured astrocytes. We first treated astrocytes prepared from rat embryos with ammonium chloride (NH₄Cl). A 72-hour NH₄Cl treatment significantly increased the expression of APP but not the APP mRNA, suggesting that the degradation of APP is suppressed. We also confirmed that ammonia is the cause of APP accumulation using ammonium acetate. By examining the cellular location of APP in astrocytes, we found that NH₄Cl facilitates the accumulation of APP in the endoplasmic reticulum (ER). Therefore, we investigated if Aβ production is occurred in the ER. We observed a significant production of Aβ₄₂, the most amyloidogenic form of the Aβ peptide, in the ER. Together, our results suggest that ammonia induces AD pathology by promoting Aβ₄₂ production in astrocytes.

2020/9/11　14:10～14:25　オンデマンドA-2 WD7 IVIgはマウス坐骨神経lysolecithin誘導脱髄領域の活性化cPLA₂に影響を与える IVIg modulate p-cPLA₂ level in the lysolecithin-induced demyelination of mouse sciatic nerve 瀬戸口潔¹、林明子¹、金子真之亮¹、馬場広子¹ 1. 東京薬科大学 Yuki Setoguchi¹, Akiko Hayashi¹, Shinnosuke Kaneko¹, Hiroko Baba¹ 1. Tokyo University of Pharmacy and Life Sciences Intravenous human immunoglobulin (IVIg) is used for treatment of immune-mediated neuropathies, including chronic inflammatory demyelinating polyneuropathy and Guillain-Barre syndrome. IVIg ameliorates muscle weakness and disturbance of motility in demyelinating neuropathy. However, the actions of IVIg on demyelinated nerves and recovery of motor function remain unclear. Previously we reported that IVIg significantly decreased demyelinating area of the sciatic nerve and early accumulation of M2-type macrophages in lysophosphatidylcholine (lysolecithin)-induced demyelination mouse model. Lysolecithin-induced demyelination is caused by the following two-step process; membrane lysis by the surfactant effects and subsequent activation of cytosolic phospholipase A₂ (cPLA₂) that causes expansion of demyelinating area. To clarify mechanism of the action of IVIg on demyelination, we examined distribution of cPLA₂ in the lysolecithin-induced demyelination with or without IVIg treatment by immunofluorescence. ICR mice were injected with 1% lysolecithin directly into bilateral sciatic nerves, and either IVIg or control saline was injected intravenously 24 hours later. The cryostat sections of sciatic nerves were examined on days 3 and 7 after lysolecithin injection. The strongly positive signal of phospho-cPLA₂ (p-cPLA₂; activated cPLA₂) was observed in the demyelinating region. The p-cPLA2-positive signal was colocalized with GFAP-positive signal, suggesting that these cells were non-myelinating Schwann cells in the lesion. The intensities of p-cPLA₂ in the demyelinating region were significantly higher at day 7 when demyelination peaks compared with those at day 3 in saline treated group. In contrast, no significant change of p-cPLA₂ intensities was observed between day 3 and day 7 in IVIg treated group. These results suggest that IVIg treatment modulates expansion of demyelinating lesion by regulating cPLA₂ activation. Thus, regulation of cPLA₂ activation may be one of the mechanisms how IVIg modify demyelinating process.		2020/9/11　14:30～14:45　オンデマンドA-2 WD8 記憶機能における神経回路形成因子LOTUSの機能解析 Functional analysis of LOTUS, a neural circuit formation factor in memory function 西田遼平¹、石川理絵²、喜田聡²、竹居光太郎¹ 1. 横浜市立大学大学院生命医科学研究科、2. 東京大学大学院農学生命科学研究科応用生命化学専攻 Ryohei Nishida¹, Rie Ishikawa², Satoshi Kida², Kohtaro Takei¹ 1. Mol. Med. Biosci. Lab., Yokohama City Univ. Grad. Sch. of Med. Life Sci., Yokohama, Japan, 2. Grad. Sch. of Agr. and Life Sci., The Univ. of Tokyo, Tokyo, Japan Overcoming the higher brain dysfunction that exhibits memory disorders, such as dementia, is an issue currently conducted all over the world. Nogo binds to Nogo receptor 1 (NgR1) and the binding inhibits axon growth and synapse formation, thereby is associated with limitation of nerve regeneration and impaired memory function. We identified the lateral olfactory tract usher substance (LOTUS) as an endogenous NgR1 antagonist. It was reported that decrease of LOTUS expression in hippocampus might be involved in impairment of memory function. However, the role of LOTUS in memory and cognitive functions has remained to be elucidated. In this study, we first examined whether LOTUS is involved in memory function. We performed social recognition test and Morris water maze test in LOTUS-gene knocking-out (LOTUS-KO) and LOTUS gene overexpressing transgenic (LOTUS-Tg) mice. We found that memory function was impaired in LOTUS-KO, whereas the function was enhanced in LOTUS-Tg mice. Next, we examined roles of LOTUS in synapse formation in cultured hippocampal neurons, and found that decrease of synaptic density in LOTUS-KO mice, while increase of the density in LOTUS-Tg mice. These results suggest that LOTUS facilitates synaptic plasticity and consequently memory function. Furthermore, a decrease in LOTUS expression level of the hippocampus was observed in accordance with aging. The memory function in LOTUS-Tg mice at 18 months age was not reduced, while the wild type mice showed decrease of the memory function at the same age. These results suggest that memory function was closely dependent on LOTUS expression level. Taken together, the data suggest that LOTUS expressed in hippocampus is related to memory and cognitive functions and maintenance of LOTUS expression level may protect from senile amnesia.