Researchers Database

osanai yasuyuki

    HistologyandcellBiology Research Associate
Last Updated :2021/11/23

Researcher Information


  • PhD(Sokendai)

Research funding number

  • 90758004

J-Global ID

Academic & Professional Experience

  • 2020/04 - Today  Jichi Medical University解剖学講座組織学部門助教
  • 2017/05 - 2020/03  Monash University, research fellow
  • 2015/04 - 2017/04  生理学研究所 博士研究員
  • 2012/04 - 2015/03  The Graduate University for Advanced Studies分子神経生理部門(池中研究室)
  • 2010/04 - 2012/03  神奈川県立平塚農業高校 理科教諭

Published Papers

  • Reiji Yamazaki, Yasuyuki Osanai, Tom Kouki, Yoshiaki Shinohara, Jeffrey K Huang, Nobuhiko Ohno
    Scientific reports 11 (1) 16906 - 16906 2021/08 
    Lysophosphatidylcholine (LPC)-induced demyelination is a versatile animal model that is frequently used to identify and examine molecular pathways of demyelination and remyelination in the central (CNS) and peripheral nervous system (PNS). However, identification of focally demyelinated lesion had been difficult and usually required tissue fixation, sectioning and histological analysis. Recently, a method for labeling and identification of demyelinated lesions in the CNS by intraperitoneal injection of neutral red (NR) dye was developed. However, it remained unknown whether NR can be used to label demyelinated lesions in PNS. In this study, we generated LPC-induced demyelination in sciatic nerve of mice, and demonstrated that the demyelinated lesions at the site of LPC injection were readily detectable at 7 days postlesion (dpl) by macroscopic observation of NR labeling. Moreover, NR staining gradually decreased from 7 to 21 dpl over the course of remyelination. Electron microscopy analysis of NR-labeled sciatic nerves at 7 dpl confirmed demyelination and myelin debris in lesions. Furthermore, fluorescence microscopy showed NR co-labeling with activated macrophages and Schwann cells in the PNS lesions. Together, NR labeling is a straightforward method that allows the macroscopic detection of demyelinated lesions in sciatic nerves after LPC injection.
  • Tatsuhide Tanaka, Nobuhiko Ohno, Yasuyuki Osanai, Sei Saitoh, Truc Quynh Thai, Kazuya Nishimura, Takeaki Shinjo, Shoko Takemura, Kouko Tatsumi, Akio Wanaka
    Glia 2021/06 
    Single oligodendrocytes produce myelin sheaths around multiple axons in the central nervous system. Interfascicular oligodendrocytes (IOs) facilitate nerve conduction, but their detailed morphologies remain largely unknown. In the present study, we three-dimensionally reconstructed IOs in the corpus callosum of adult mouse using serial block face scanning electron microscopy. The cell bodies of IOs were morphologically polarized and extended thick processes from the cytoplasm-rich part of the cell. Processes originating from the cell body of each IO can be classified into two types: one myelinates an axon without branching, while the other type branches and each branch myelinates a distinct axon. Myelin sheaths originating from a particular IO have biased thicknesses, wrapping axons of a limited range of diameters. Consistent with this finding, IOs transduced and visualized with a rabies viral vector expressing GFP showed statistically significant variation in their myelination patterns. We further reconstructed the sheath immediately adjacent to that derived from each of the analyzed IOs; the thicknesses of the pair of sheaths were significantly correlated despite emanating from different IOs. These results suggest that a single axon could regulate myelin sheath thicknesses, even if the sheaths are derived from distinct IOs. Collectively, our results indicate that the IOs have their own myelin profiles defined by myelin thickness and axonal diameter although axons may regulate thickness of myelin sheath.
  • Kazuo Kunisawa, Nobuhiko Hatanaka, Takeshi Shimizu, Kenta Kobayashi, Yasuyuki Osanai, Akihiro Mouri, Qian Shi, Manzoor A Bhat, Atsushi Nambu, Kazuhiro Ikenaka
    Molecular brain 13 (1) 159 - 159 2020/11 
    Paranodal axoglial junctions are essential for rapid nerve conduction and the organization of axonal domains in myelinated axons. Neurofascin155 (Nfasc155) is a glial cell adhesion molecule that is also required for the assembly of these domains. Previous studies have demonstrated that general ablation of Nfasc155 disorganizes these domains, reduces conduction velocity, and disrupts motor behaviors. Multiple sclerosis (MS), a typical disorder of demyelination in the central nervous system, is reported to have autoantibody to Nfasc. However, the impact of focal loss of Nfasc155, which may occur in MS patients, remains unclear. Here, we examined whether restricted focal loss of Nfasc155 affects the electrophysiological properties of the motor system in vivo. Adeno-associated virus type5 (AAV5) harboring EGFP-2A-Cre was injected into the glial-enriched internal capsule of floxed-Neurofascin (NfascFlox/Flox) mice to focally disrupt paranodal junctions in the cortico-fugal fibers from the motor cortex to the spinal cord. Electromyograms (EMGs) of the triceps brachii muscles in response to electrical stimulation of the motor cortex were successively examined in these awake mice. EMG analysis showed significant delay in the onset and peak latencies after AAV injection compared to control (Nfasc+/+) mice. Moreover, EMG half-widths were increased, and EMG amplitudes were gradually decreased by 13 weeks. Similar EMG changes have been reported in MS patients. These findings provide physiological evidence that motor outputs are obstructed by focal ablation of paranodal junctions in myelinated axons. Our findings may open a new path toward development of a novel biomarker for an early phase of human MS, as Nfasc155 detects microstructural changes in the paranodal junction.
  • Takeshi Shimizu, Yasuyuki Osanai, Kenji F Tanaka, Truc Quynh Thai, Manabu Abe, Rie Natsume, Kenji Sakimura, Kazuhiro Ikenaka
    Journal of neurochemistry 150 (2) 158 - 172 2019/07 [Refereed][Not invited]
    Oligodendrocytes (OLs) are myelinating cells of the central nervous system. Recent studies have shown that mechanical factors influence various cell properties. Mechanical stimulation can be transduced into intracellular biochemical signals through mechanosensors, such as integrin, p130Cas, talin and vinculin. However, the molecular mechanisms underlying the mechanical regulation of OLs by mechanosensors remain largely unknown. We found that morphology of OL was affected by knockdown of the mechanosensors p130Cas or talin1. Stretching of OL precursor cells induced the phosphorylation of p130Cas and talin-associated assembly of vinculin. Shear stress decreased the number of OL processes, whereas these effects were mechanically suppressed by dominant-negative (DN) p130Cas, but not by DN-talin1. To investigate the roles of p130Cas in post-natal OLs in vivo, we constructed a novel p130Cas knock-in mouse and found overexpression of p130Cas in vivo affected the number of mature OLs in the cortex. These results indicate that the mechanosensor p130Cas controls both OL morphogenesis and maturation.
  • Kazuo Kunisawa, Takeshi Shimizu, Itaru Kushima, Branko Aleksic, Daisuke Mori, Yasuyuki Osanai, Kenta Kobayashi, Anna M Taylor, Manzoor A Bhat, Akiko Hayashi, Hiroko Baba, Norio Ozaki, Kazuhiro Ikenaka
    Journal of neurochemistry 147 (3) 395 - 408 2018/11 [Refereed][Not invited]
    Myelinated axons segregate the axonal membrane into four defined regions: the node of Ranvier, paranode, juxtaparanode, and internode. The paranodal junction consists of specific component proteins, such as neurofascin155 (NF155) on the glial side, and Caspr and Contactin on the axonal side. Although paranodal junctions are thought to play crucial roles in rapid saltatory conduction and nodal assembly, the role of their interaction with neurons is not fully understood. In a previous study, conditional NF155 knockout in oligodendrocytes led to disorganization of the paranodal junctions. To examine if disruption of paranodal junctions affects neuronal gene expression, we prepared total RNA from the retina of NF155 conditional knockout, and performed expression analysis. We found that the expression level of 433 genes changed in response to paranodal junction ablation. Interestingly, expression of aquaporin 3 (AQP3) was significantly reduced in NF155 conditional knockout mice, but not in cerebroside sulfotransferase knockout (CST-KO) mice, whose paranodes are not originally formed during development. Copy number variations have an important role in the etiology of schizophrenia (SCZ). We observed rare duplications of AQP3 in SCZ patients, suggesting a correlation between abnormal AQP3 expression and SCZ. To determine if AQP3 over-expression in NF155 conditional knockout mice influences neuronal function, we performed adeno-associated virus (AAV)-mediated over-expression of AQP3 in the motor cortex of mice and found a significant increase in caspase 3-dependent neuronal apoptosis in AQP3-transduced cells. This study may provide new insights into therapeutic approaches for SCZ by regulating AQP3 expression, which is associated with paranodal disruption.
  • Yasuyuki Osanai, Takeshi Shimizu, Takuma Mori, Nobuhiko Hatanaka, Yoshitaka Kimori, Kenta Kobayashi, Shinsuke Koyama, Yumiko Yoshimura, Atsushi Nambu, Kazuhiro Ikenaka
    Glia 66 (11) 2514 - 2525 2018/11 [Refereed][Not invited]
    Oligodendrocytes myelinate neuronal axons to increase conduction velocity in the vertebrate central nervous system (CNS). Recent studies revealed that myelin formed on highly active axons is more stable compared to activity-silenced axons, and length of the myelin sheath is longer in active axons as well in the zebrafish larva. However, it is unclear whether oligodendrocytes preferentially myelinate active axons compared to sensory input-deprived axons in the adult mammalian CNS. It is also unknown if a single oligodendrocyte forms both longer myelin sheaths on active axons and shorter sheaths on input-deprived axons after long-term sensory deprivation. To address these questions, we applied simultaneous labeling of both neuronal axons and oligodendrocytes to mouse models of long-term monocular eyelid suturing and unilateral whisker removal. We found that individual oligodendrocytes evenly myelinated normal and input-deprived axons in the adult mouse CNS, and myelin sheath length on normal axons and input-deprived axons formed by a single oligodendrocyte were comparable. Importantly, the average length of the myelin sheath formed by individual oligodendrocytes did change depending on relative abundance of normal against sensory-input deprived axons, indicating an abundance of deprived axons near an oligodendrocyte impacts on myelination program by a single oligodendrocyte.
  • Takeshi Shimizu, Yasuyuki Osanai, Kazuhiro Ikenaka
    Neurochemical research 43 (1) 190 - 194 2018/01 [Refereed][Not invited]
    In the past, glial cells were considered to be 'glue' cells whose primary role was thought to be merely filling gaps in neural circuits. However, a growing number of reports have indicated the role of glial cells in higher brain function through their interaction with neurons. Myelin was originally thought to be just a sheath structure surrounding neuronal axons, but recently it has been shown that myelin exerts effects on the conduction velocity of neuronal axons even after myelin formation. Therefore, the investigation of glial cell properties and the neuron-glial interactions is important for understanding higher brain function. Moreover, since there are many neurological disorders caused by glial abnormalities, further understanding of glial cell-related diseases and the development of effective therapeutic strategies are warranted. In this review, we focused on oligodendrocyte-neuron interactions, with particular attention on (1) axonal signals underlying oligodendrocyte differentiation and myelination, (2) neuronal activity-dependent myelination and (3) the effects of myelination on higher brain function.
  • Takeshi Shimizu, Yasuyuki Osanai, Kenji F Tanaka, Manabu Abe, Rie Natsume, Kenji Sakimura, Kazuhiro Ikenaka
    Glia 65 (2) 360 - 374 2017/02 [Refereed][Not invited]
    Oligodendrocytes (OLs) are myelinating cells of the central nervous system. Recent studies have shown that mechanical factors influence various cell properties. Mechanical stimuli can be transduced into intracellular biochemical signals through mechanosensors and intracellular mechanotransducers, such as YAP. However, the molecular mechanisms underlying mechanical regulation of OLs by YAP remain unknown. We found that OL morphology and interactions between OLs and neuronal axons were affected by knocking down YAP. Mechanical stretching of OL precursor cells induced nuclear YAP accumulation and assembly of focal adhesion, key platforms for mechanotransduction. Shear stress decreased the number of OL processes, whereas a dominant-negative form of YAP suppressed these effects. To investigate the roles of YAP in postnatal OLs in vivo, we constructed a novel YAP knock-in mouse and found that in vivo overexpression of YAP widely affected OL maturation. These results indicate that YAP regulates OL morphology and maturation in response to mechanical factors. GLIA 2017;65:360-374.
  • Yasuyuki Osanai, Takeshi Shimizu, Takuma Mori, Yumiko Yoshimura, Nobuhiko Hatanaka, Atsushi Nambu, Yoshitaka Kimori, Shinsuke Koyama, Kenta Kobayashi, Kazuhiro Ikenaka
    Glia 65 (1) 93 - 105 2017/01 [Refereed][Not invited]
    Oligodendrocytes myelinate neuronal axons during development and increase conduction velocity of neuronal impulses in the central nervous system. Neuronal axons extend from multiple brain regions and pass through the white matter; however, whether oligodendrocytes ensheath a particular set of axons or do so randomly within the mammalian brain remains unclear. We developed a novel method to visualize individual oligodendrocytes and axon derived from a particular brain region in mouse white matter using a combinational injection of attenuated rabies virus and adeno-associated virus. Using this method, we found that some populations of oligodendrocytes in the corpus callosum predominantly ensheathed axons derived from motor cortex or sensory cortex, while others ensheathed axons from both brain regions, suggesting heterogeneity in preference of myelination toward a particular subtype of neurons. Moreover, our newly established method is a versatile tool for analyzing precise morphology of each oligodendrocyte in animal models for demyelinating disorders and addressing the role of oligodendrocyte in higher brain functions. GLIA 2016. GLIA 2017;65:93-105.

Awards & Honors

  • 2016/09 Japanese Society for Neurochemistry Best young oral presentation

Research Grants & Projects

  • 新規オリゴデンドロサイト-神経軸索同時標識法の開発と応用
    日本学術振興会:科学研究費助成事業 若手研究
    Date (from‐to) : 2021/04 -2024/03
  • 視覚神経回路形成におけるオリゴデンドロサイトの機能解析
    日本学術振興会:科学研究費助成事業 研究活動スタート支援
    Date (from‐to) : 2020/09 -2022/03 
    Author : 長内 康幸
  • オリゴデンドロサイトによる髄鞘形成の記憶や学習における役割の解明
    The Naito Foundation:The Naito Foundation Grant for Studying Overseas

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