若手道場 グループＣ
Wakate Dojo group C |
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| 2020/9/12 13:00～13:15 オンデマンドA-1
WD9
新規マイオカインのPKM2は慢性期脊髄損傷の運動機能を回復する
New myokine, PKM2 recovers motor function in chronic phase of spinal cord injury
*須山 真聡1、菊池 高弘、中野 葵、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
*Masato Suyama1, Takahiro Kikuchi, Aoi Nakano, Chihiro Tohda1
1. Toyama Univ. Institute of Natural Medicine, Section of Neuromedical Science
Functional recovery in chronic phase after spinal cord injury (SCI) is very untreatable by any medical treatments. However, establishing effective intervention for SCI, especially for chronic phase SCI was progressed, successful challenges have not been achieved yet.
Our previous study (J. Neurotrauma (2019) 36(12):1935-1948.) found that herbal medicine-derived compound, acteoside, improved motor function in chronic SCI mice by intramuscular injection to hindlimbs. Very interestingly, acteoside treatment activated pyruvate kinase M2 (PKM2) secretion from the skeletal muscle of hindlimbs. Secreted form, that is extracellular PKM2 revealed axonal growth activity in cultured neurons. These results let us suppose that PKM2 might be a new myokine and be responsible for repairing neuraxis. Therefore, this study aimed to investigate PKM2 itself could recover motor function of chronic SCI.
Recombinant PKM2 was continuously infused to the lateral ventricle of SCI mice at chronic phase after injury. Compared with vehicle solution-infused group, PKM2 group significantly improved hindlimb function. Density of raphespinal tracts (5-HT-positive axons) in the spinal cord by PKM2 treatment. In addition, retrograde transsynaptic tracing showed that raphespinal tracts with synaptic connecting to motor neurons were clearly increased by PKM2.
Next, we comprehensively explored a direct target molecule of extracellular PKM2 in neurons. Using DARTS method, we identified Valocin-Containing Protein (VCP) as a direct binding protein of PKM2 in neurons. PKM2 increased ATPase activity of VCP, and the PKM2-induced axonal growth phenomenon and functional recovery in SCI mice were mediated by the VCP activity. These results suggest that PKM2-VCP signaling is a novel important pathway to make possible recovery even after the late phase in SCI. We are now doing additional challenges to achieve further improvement of the efficacy. | | 2020/9/12 13:20～13:35 オンデマンドA-1
WD10
アストロサイトにおけるグルタミン合成酵素の発現はYAPによって制御される
Expression of astrocytic glutamine synthetase is regulated by YAP
*岸川 咲吏1、照沼 美穂1
1. 新潟大学大学院医歯学総合研究科 口腔生化学分野
*Sari Kishikawa1, Miho Terunuma1
1. Div. of Oral Biochemistry, Niigata Univ. Grad. Sch. of Medical and Dental Science, Niigata.
Astrocytes, one of the major cells in the central nervous system, are the only cells in the brain that metabolize a neurotoxic ammonium and glutamate into glutamine using the enzyme called glutamine synthetase (GS). Although the astrocytic GS is an essential enzyme that maintains brain integrity, the mechanism regulating GS expression remains elusive. Here, we report that ammonia plays a central role in regulating GS expression. Ammonium concentration-dependent decrease in GS expression was found at both protein and mRNA level, suggesting that ammonia may regulate GS transcription and/or translation.
Yes-associated protein (YAP) is known as an effector of the Hippo pathway, which promotes cell proliferation and suppresses cell death through the induction of various genes. In astrocytes, YAP has been reported to promote cellular differentiation (Xie et al, J Neurosci, 2020), and recent study has shown that it also regulates the expression of GS in the liver (Cox AG et al., Nat Cell Biol, 2016). To determine if ammonia alters YAP function, we examined its cellular localization. We found that ammonia-treated astrocytes greatly reduced the expression of YAP in the nucleus, suggesting that YAP-dependent transcription is reduced. To examine if YAP is the regulator of astrocytic GS, we used verteporfin, a YAP inhibitor, and found that it significantly inhibits the expression of GS. These findings may link to the pathophysiology of neurological diseases such as epilepsy and ischemia which GS downregulation has been reported. | | 2020/9/12 13:40～13:55 オンデマンドA-1
WD11
光ファイバーマイクロドライブの開発
Development of an optical fiber with micro-drive device
*河野 晏奈1、山浦 克典1、田中 謙二1
1. 慶應義塾大学
*Anna Kono1, Katsunori Yamaura1, Kenji Tanaka1
1. Keio University
Pioneering studies demonstrated that the fiber photometry system enabled compound activity monitoring from defined cell populations. Monitoring of cell activity in the deep brain structure, e.g. the striatum, and that in freely moving condition are the advantages of this system. On the other hand, a low spatial resolution is the disadvantage. Moreover, in the prevailing system, the researcher can examine the only one target brain region where the tips of the optical fiber covers.
To increase the monitoring points, one solution is to use the multi-fiber photometry system. The other solution is to develop the system in which the monitoring point is mobile. We took advantages of the micro-drive device in the electrophysiology and equipped it for the fiber photometry system. An optic fiber with micro-drive device permitted us to move an optic fiber vertically with 2 mm mobile range. As a result, we were able to monitor the activities from the stiatopallidal neurons located the dorsal to the ventral striatum.
We examined the role of striatopallidal neurons along with dorsoventral axis on goal-directed behavior using a new device. We used transgenic mice expressing Ca indicator only in the striatopallidal neurons and employed a food-seeking lever press operant task. After task acquisition, mice conducted the task every day. We started the monitoring from the dorsal striatum and pushed the optic fiber toward the ventral side every 250 µm per day. We found the unique change of activities along with dorsoventral axis by multiple-point monitoring. | | 2020/9/12 14:00～14:15 オンデマンドA-1
WD12
マウス脳においてリン酸化がもたらすタウの微小管結合能への影響
Phosphorylation of microtubule associated protein tau regulates its ability to assemble into microtubules in mice brains
*萩田 彩香1、角田 聡子1、延原 美香1、角田 伸人1、宮坂 知宏1
1. 同志社大学
*Ayaka Hagita1, Satoko Kakuda1, Mika Nobuhara1, Nobuto Kakuda1, Tomohiro Miyasaka1
1. Doshisha Univ.
Tau is a microtubule associated protein (MAP) that has abilities to bind on microtubules (MTs) and stabilize them. Tau is also identified as a framework of insoluble inclusions, formed in the affected neurons in the brains of dementia, tauopathy. Because the abnormal tau purified from neurofibrillary tangles were hyperphosphorylated and lost its functions, it is considered that the phosphorylation of tau may affect its functions onto MTs. However, in fact, the effects of the phosphorylation on the physiological functions of tau in vivo remain obscure.
To analyze the MT-formation in mice brains, we optimized the procedure that enables to quantify not only stable- but also labile-MTs and the behavior of MAPs in vivo. Using this method, we found that more than 80% of tau in adult brains were bound on MTs. Tau recovered in soluble free-tubulin fraction was associated with tubulin and still had an ability to assemble to labile-MTs, but not stable-MTs. In the brains of hypothermia model, hyperphosphorylated tau became free and lost its functions, although the populations of tubulin fractioned into free and labile-MTs were unaffected. We further analyzed the MT-formation in the postnatal stages in mice brains. Stable-MTs were gradually increased according to the days after birth. Tau was highly phosphorylated in MT-unbound fraction in the first week of life, then dephosphorylated until P14. According to its dephosphorylation, tau came to assemble into MTs.
These findings suggest that phosphorylation regulates the functions of tau on MTs in healthy mouse brains. | |
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