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KOMADA Munekazu

    Department of Life Science　Lecturer
Last Updated :2024/04/25

Researcher Information

URL

J-Global ID

Research Areas

  • Life sciences / Anatomy

Academic & Professional Experience

  • 2020/04 - Today  Kindai UniversityFaculty of Science and Engnieering, Life ScienceLecturer

Association Memberships

  • 日本毒性学会   THE JAPAN NEUROSCIENCE SOCIETY   THE JAPANESE TERATOLOGY SOCIETY   

Published Papers

  • Munekazu Komada; Tetsuji Nagao; Nao Kagawa
    Journal of applied toxicology : JAT 2020/07 [Refereed]
     
    Di-2-ethylhexyl phthalate (DEHP) is the most commonly used phthalate for the production of flexible polyvinyl chloride. Recent studies in humans reported a widespread DEHP exposure, raising concerns in infants whose metabolic and excretory systems are immature. DEHP is a potential endocrine-disrupting chemical, but the effects of postnatal DEHP exposure on neuronal development are unclear. The dentate gyrus (DG) is critical in the consolidation of information from short- to long-term memory, as well as spatial learning. We evaluated neurodevelopmental toxicity due to neonatal DEHP exposure by assessing neurogenesis in the DG. Newborn mice were orally administered DEHP from postnatal day (PND) 12 to 25. We performed immunostaining using neuronal markers at different stages to assess whether DEHP exposure affects neurons at specific differentiation stages at PND 26 and PND 110. We found that in mice, postnatal DEHP exposure led to a decrease in the number of Type-1, -2a, -2b, and -3 neural progenitor cells, as well as granule cells in the hippocampal DG at PND 26. Further, the results showed that neural progenitor cell proliferation and differentiation were also reduced in the hippocampal DG of the DEHP-exposed mice. However, no effect on memory and learning was observed. Overall, our results suggest that neurodevelopmental toxicity due to postnatal DEHP exposure might affect postnatal DG morphogenesis.
  • Munekazu Komada; Tetsuji Nagao; Nao Kagawa
    The Journal of toxicological sciences 45 (10) 639 - 650 2020 [Refereed]
     
    Bisphenol A (BPA), an endocrine disruptor with estrogenic effects, is widely used as a raw material for manufacturing polycarbonate plastic and epoxy resins. Prenatal and postnatal exposure to BPA affects brain morphogenesis. However, the effects of prenatal and postnatal BPA exposure on postnatal neurogenesis in mice are poorly understood. In this study, we developed a mouse model of prenatal and postnatal BPA exposure and analyzed its effects on hippocampal neurogenesis. The hippocampal dentate gyrus is vulnerable to chemical exposure, as neurogenesis continues in this region even after birth. Our results showed that in mice, prenatal and postnatal BPA exposure decreased the number of type-1, 2a, 2b, and 3 neural progenitor cells, as well as in granule cells, in the hippocampal dentate gyrus on postnatal days 16 and 70. The effect of prenatal and postnatal BPA exposure on neural progenitors were affected at all differentiation stages. In addition, prenatal and postnatal BPA exposure affects the maintenance of long-term memory on postnatal day 70. Our results suggest that neurodevelopmental toxicity due to prenatal and postnatal BPA exposure might affect postnatal morphogenesis and functional development of the hippocampal dentate gyrus.
  • Mifumi Takahashi; Munekazu Komada; Ken Miyazawa; Shigemi Goto; Yayoi Ikeda
    Toxicology Letters Elsevier Ireland Ltd 284 113 - 119 1879-3169 2018/03 [Refereed]
     
    Bisphenol A (BPA) is a widely used compound in the food packaging industry. Prenatal exposure to BPA induces histological abnormalities in the neocortex and hypothalamus in association with abnormal behaviors. Yet, the molecular and cellular neurodevelopmental toxicological mechanisms of BPA are incompletely characterized on neuroinflammatory-related endopoints. To evaluate the neurodevelopmental effects of BPA exposure in mouse embryos, we examined microglial numbers as well as the expression of microglial-related factors in the E15.5 embryonic brain. BPA-exposed embryos exhibited significant increases in Iba1-immunoreactive microglial numbers in the dorsal telencephalon and the hypothalamus compared to control embryos. Further, the expression levels of microglial markers (Iba1, CD16, iNOS, and CD206), inflammatory factors (TNFα and IL4), signal transducing molecules (Cx3Cr1 and Cx3Cl1), and neurotrophic factor (IGF1) were altered in BPA-exposed embryos. These findings suggest that BPA exposure increases microglial numbers in the brain and alters the neuroinflammatory status at a transcriptional level. Together, these changes may represent a novel target for neurodevelopmental toxicity assessment after BPA exposure.
  • 高橋 美文; 駒田 致和; 田渕 雅子; 宮澤 健; 後藤 滋巳; 池田 やよい
    愛知学院大学歯学会誌 愛知学院大学歯学会 55 (4) 311 - 321 0044-6912 2017/12 
    チミジン類似物質である5-Chloro-2'-deoxyuridine(CldU)と5-Iodo-2'-deoxyuridine(IdU)を、異なる時期に妊娠マウスに投与し胎仔に取り込ませ、胎仔の増殖中の細胞をラベリングした。胎仔から作製した脳の切片に、細胞増殖マーカーに対する2つの抗体を用いて多重免疫染色を行った。増殖中の細胞を増殖時期の違いによって異なる色で示し、視床下部の増殖細胞の分布と細胞の誕生時期を解析した。その結果、視床下部の神経細胞は第3脳室に面する脳室帯最内層で誕生後、脳室帯の外側へ移動し、細胞増殖は胎生12.5日に最も活発で、胎生18.5日に終了した。次いで、視床下部の背側に発現するOrthopedia(Otp)陽性神経細胞、腹側に発現するSteroidgenic factor 1(SF1)陽性神経細胞の誕生時期を解析し、視床下部背側および腹側領域の発生について検討した。その結果、胎生12.5日にOtp陽性神経細胞は視床下部の背側に、SF1陽性神経細胞は腹側に存在し、胎生18.5日には両域に存在した。以上、視床下部の神経細胞は背側でより早期に誕生している可能性が示唆された。
  • Munekazu Komada; Nao Hara; Satoko Kawachi; Kota Kawachi; Nao Kagawa; Tetsuji Nagao; Yayoi Ikeda
    SCIENTIFIC REPORTS NATURE PUBLISHING GROUP 7 (1) 4934  2045-2322 2017/07 [Refereed]
     
    Fetal alcohol spectrum disorders (FASD) constitute a wide range of disorders that arise from prenatal exposure to ethanol (EtOH). However, detailed reports regarding the adverse effects of prenatal EtOH exposure on neocortical morphology and its underlying pathogenic mechanisms are limited. In the present study, we aimed to characterize the anatomical abnormalities of neocortical development and their correlation with microglial properties and neuro-inflammation in a mouse model of FASD. We evaluated the development and maturation of the neocortex in ICR mice prenatally exposed to 25% (w/v) EtOH using histological and molecular analyses. Reduced proliferation and excessive cell death were observed in the dorsal telencephalon. Abnormal neuronal distribution, layer formation, and dopaminergic neuronal projections were observed in the neocortex. Disruption of microglial differentiation (M-1/M-2 microglial ratio) and abnormal expression of pro-inflammatory and neurotrophic factors were induced, and these abnormalities were ameliorated by co-treatment with an antiinflammatory drug (pioglitazone). FASD model mice displayed histological abnormalities, microglial abnormalities, and neuro-inflammation in both the embryonic and newborn stages. Thus, antiinflammatory therapeutics may provide a novel preventive approach for the treatment of FASD.
  • Yayoi Ikeda; Ayako Tagami; Munekazu Komada; Mifumi Takahashi
    NEUROENDOCRINOLOGY KARGER 105 (4) 357 - 371 0028-3835 2017 [Refereed]
     
    Background: Kisspeptins are important regulators of the development and function of the hypothalamic-pituitary-gonadal axis. However, the importance of kisspeptin at the pituitary level is unclear. Methods: We examined the expression profile of kisspeptin in the mouse pituitary during development and in adulthood using RT-PCR, quantitative PCR and immunohistochemistry. Results: Kiss1 mRNA was detected in both embryonic and postnatal pituitaries. Kisspeptin- immunoreactive (+) cells were detected from embryonic day (E) 13.5 throughout adulthood, being localized to the rostroventral portion in the anterior pituitary (AP) in embryos, and also to the dorsocaudal AP postnatally. A large proportion of kisspeptin(+) cells were double-labeled with gonadotrope markers including Foxl2, SF-1, and LH beta, and the percentage of LH beta(+) cells in kisspeptin(+) cells increased during development. No kisspeptin(+) cells were positive for the proliferating cell marker MCM7 (minichromosome maintenance protein 7), but a few kisspeptin(+) cells co-expressed the stem/progenitor cell marker Sox2. Kisspeptin expression was similar between sexes and between agonadal SF-1 knockout embryos and wild-type littermates. Kiss1 mRNA levels were not significantly different between sexes or during early postnatal development, but levels in females increased when puberty began and were significantly higher than in males at postpubertal ages. Conclusions: These results suggest that kisspeptin is expressed in gonadotrope precursors during gonadotrope differentiation, and that kisspeptin expression begins soon after the initiation of aGSU production and is extinguished soon after the initiation of LH production. Furthermore, pituitary kisspeptin expression may be regulated in a gonad-independent manner during development, but may be associated with gonadotrope function in adulthood. (C) 2016 S. Karger AG, Basel
  • Munekazu Komada; Yuuya Gendai; Nao Kagawa; Tetsuji Nagao
    TOXICOLOGY LETTERS ELSEVIER IRELAND LTD 259 69 - 79 0378-4274 2016/09 [Refereed]
     
    Di(2-ethylhexyl) phthalate (DEHP) is currently the most commonly used phthalate for the production of flexible polyvinyl chloride. Phthalates including DEHP have been labeled as potential endocrine disruptors. The effect on the development of the neocortex, however, is unknown. To evaluate the neurodevelopmental effects of prenatal DEHP exposure at 1 and 100 mg/kg/day or 100 and 500 mg/kg/day in fetal and newborn mice, we performed a detailed histologic analysis of the developing dorsal telencephalon and neocortex. The observation of fetuses exposed to DEHP revealed reductions of proliferation and neurogenesis (1 and 100 mg/kg) and an increase in cell death (500 mg/kg). In addition, the newborns prenatally exposed to DEHP showed an abnormal neuronal distribution and a decrease in neurons. These findings suggest that prenatal DEHP exposure induces neurodevelopmental toxicity associated with the neural stem cell niche and corticogenesis. (C) 2016 Elsevier Ireland Ltd. All rights reserved.
  • Momoko Nagai; Katsura Minegishi; Munekazu Komada; Maiko Tsuchiya; Tomomi Kameda; Shigehito Yamada
    CONGENITAL ANOMALIES WILEY-BLACKWELL 56 (3) 112 - 118 0914-3505 2016/05 [Refereed]
     
    The "Kyoto Collection of Human Embryos" at Kyoto University was begun in 1961. Although morphological analyses of samples in the Kyoto Collection have been performed, these embryos have been considered difficult to genetically analyze because they have been preserved in formalin or Bouin's solution for 20-50 years. Owing to the recent advances in molecular biology, it has become possible to extract DNA from long-term fixed tissues. The purpose of this study was to extract DNA from wet preparations of human embryo samples after long-term preservation in fixing solution. We optimized the DNA extraction protocol to be suitable for tissues that have been damaged by long-term fixation, including DNA-protein crosslinking damage. Diluting Li2CO3 with 70% ethanol effectively removed picric acid from samples fixed in Bouin's solution. Additionally, 20.0mg/mL proteinase was valuable to lyse the long-term fixed samples. The extracted DNA was checked with PCR amplification using several sets of primers and sequence analysis. The PCR products included at least 295- and 838-bp amplicons. These results show that the extracted DNA is applicable for genetic analyses, and indicate that old embryos in the Kyoto Collection should be made available for future studies. The protocol described in this study can successfully extract DNA from old specimens and, with improvements, should be applicable in research aiming to understand the molecular mechanisms of human congenital anomalies.
  • KOMADA Munekazu; KAWACHI Kota; ITO Saki; HARA Nao; NAGAO Tetsuji; IKEDA Yayoi
    Annual Meeting of the Japanese Society of Toxicology The Japanese Society of Toxicology 43 O - 22 2016 
    胎児期あるいは新生児期にアルコールに曝露すると、特徴的な頭部顔面の形成異常や、発達・学習障害、行動異常などを示す胎児アルコール症候群を発症することが知られている。アルコールは妊娠・授乳中にも摂取しやすく、また他の催奇形物質と異なり毒性の閾値が明確でないこと、個人差が大きいことなどから、その危険性や発症機序を明らかにすることは急務であるが、特に発達・学習障害や行動異常の原因については不明な点が多い。そこで本研究課題では、エタノール曝露モデルマウスとして、妊娠6日から18日（12：00と18：00の2回投与、投与前2時間は絶食）まで25％(w/v)のエタノール0.5、1、2 g/kg体重をICRマウスに強制経口投与し、その胎児・新生児を用いて形態学・行動学的解析を行った。胎児期においては細胞増殖に異常が見られた。これらの異常は新生児期に、神経細胞の分布や投射の異常、大脳皮質の層構造の形成異常に繋がっていることが示唆された。さらに、新生児期と成熟期の神経機能の異常を調べるために行動解析を行ったところ、新生児期（生後1日）の振戦が増加し、成熟期においても活動量の亢進が見られた。近年、胎児期のエタノール曝露は脳内に炎症を引き起こし、それが一因となりミクログリアに影響を及ぼしていることが示唆されている。本モデルマウスにおいても、胎児期、新生児期において異常な増加や活性化が見られた。また、ミクログリアの活性に関連するサイトカイン、栄養因子、細胞外シグナルにも影響が確認された。これらの異常は、大脳皮質の発生において細胞増殖に異常を誘発し、組織構築や神経投射に影響を及ぼし、さらには新生児、成熟期に活動量の亢進といった行動異常の原因となる可能性を示した。
  • Yagi, H; Oka, Y; Komada, M; Xie, M.J; Noguchi, K; Sato, M
    Neuroscience Letters 612 18 - 24 1872-7972 2016/01 [Refereed]
     
    The callosal connections between the two hemispheres of the neocortex are altered in certain psychiatric disorders including schizophrenia. However, how and why the callosal connection is impaired in patients suffering from psychiatric diseases remain unclear. Filamin A interacting protein (FILIP), whose alteration through mutation relates to schizophrenic pathogenesis, binds to actin-binding proteins and controls neurotransmission. Because cortical excitatory neurons, including callosal projection neurons, migrate to the cortical plate during development, with the actin-binding proteins playing crucial roles during migration, we evaluated whether FILIP is involved in the development of the callosal projection neurons by histological analysis of Filip-knockout mice. The positioning of the callosal projection neurons, especially those expressing Plxnd1, in the superficial layer of the cortex is disturbed in these mice, which suggests that FILIP is a key molecule that links callosal projections to the pathogenesis of brain disorders.
  • Hideshi Yagi; Yuichiro Oka; Munekazu Komada; Min-Jue Xie; Koichi Noguchi; Makoto Sato
    NEUROSCIENCE LETTERS ELSEVIER IRELAND LTD 612 18 - 24 0304-3940 2016/01 [Refereed]
     
    The callosal connections between the two hemispheres of the neocortex are altered in certain psychiatric disorders including schizophrenia. However, how and why the callosal connection is impaired in patients suffering from psychiatric diseases remain unclear. Filamin A interacting protein (FILIP), whose alteration through mutation relates to schizophrenic pathogenesis, binds to actin-binding proteins and controls neurotransmission. Because cortical excitatory neurons, including callosal projection neurons, migrate to the cortical plate during development, with the actin-binding proteins playing crucial roles during migration, we evaluated whether FILIP is involved in the development of the callosal projection neurons by histological analysis of Filip-knockout mice. The positioning of the callosal projection neurons, especially those expressing Plxnd1, in the superficial layer of the cortex is disturbed in these mice, which suggests that FILIP is a key molecule that links callosal projections to the pathogenesis of brain disorders. (C) 2015 Elsevier Ireland Ltd. All rights reserved.
  • Munekazu Komada; Mifumi Takahashi; Yayoi Ikeda
    NEUROSCIENCE LETTERS ELSEVIER IRELAND LTD 600 85 - 90 0304-3940 2015/07 [Refereed]
     
    The nuclear receptor steroidogenic factor-1 (SF-1) plays essential roles in the development and function of the endocrine and reproductive systems. During embryogenesis, SF-1 is expressed in the ventromedial hypothalamic nucleus (VMH) and regulates the migratibn and terminal differentiation of the VMH neurons. Additionally, in situ hybridization data indicated SF-1 expression in the dorsal telencephalon at embryonic day (E) 13.5. In this study, we investigated the neocortical development in SF-1 knockout (KO) mouse embryos. The number of neurons was increased in the intermediate/subventricular zones and decreased in the cortical plate in the SF-1 KO embryos. SF-1 KO embryos produced more neural stem/progenitor cells, especially apical progenitor cells, and showed abnormal radial glial fiber morphology. The increase in neural stem/progenitor cells was caused by an increased S-phase fraction in the proliferative cells and the inhibition of cell cycle exit in these cells. The mRNA expression of the estrogen receptor ESR alpha was up-regulated and that of the estrogen synthetase Cyp19a1 was down-regulated in the dorsal telencephalon of SF-1 KO embryos. We showed that SF-I is expressed in the dorsal telencephalon at E15.5 and E18.5, but not in adult animals. Our data demonstrated that SF-1 is involved in cell cycle regulation, neurogenesis, and neuronal migration via controlling the estrogen signaling for proper neocortical development. (C) 2015 Elsevier Ireland Ltd. All rights reserved.
  • Kagawa,N; M. Komada; T. Nagao
    Fundam. Toxicol. Sci. The Japanese Society of Toxicology 2 (2) 79 - 82 2189-115X 2015/05 [Refereed]
     
    Studies on the low-dose effects of xenoestrogens have yielded conflicting results that may have resulted from differences in estrogen sensitivity between the mouse strains used. We developed a mouse newborn behavioral testing method for evaluating the risk of neurotoxicity of environmental chemicals, by means of determining a newborn's motor activity through applying the tare function of an analytical balance. Motor activities including crawling, pivoting, and tremors of C57BL/6J and ICR mouse newborns exposed to bisphenol A (BPA) at 200 µg/kg/day on embryonic days 6 through 18 were evaluated for 5 min on postnatal day 1 by the testing method. Motor activities of mature male offspring exposed prenatally to BPA were also evaluated in wheel cage and open field tests. Maternal BPA oral dosing increased the motor activity in newborns of both strains and mature offspring of the C57BL/6J strain. The findings indicate that both mouse strains provide adequate models for the newborn neurobehavioral study of prenatal exposure to environmentally relevant levels of estrogen-mimicking chemicals.
  • Masayuki Okamoto; Tokuichi Iguchi; Tsuyoshi Hattori; Shinsuke Matsuzaki; Yoshihisa Koyama; Manabu Taniguchi; Munekazu Komada; Min-Jue Xie; Hideshi Yagi; Shoko Shimizu; Yoshiyuki Konishi; Minoru Omi; Tomohiko Yoshimi; Taro Tachibana; Shigeharu Fujieda; Taiichi Katayama; Akira Ito; Shinji Hirotsune; Masaya Tohyama; Makoto Sato
    JOURNAL OF NEUROSCIENCE SOC NEUROSCIENCE 35 (7) 2942 - 2958 0270-6474 2015/02 [Refereed]
     
    Cell positioning and neuronal network formation are crucial for proper brain function. Disrupted-in-Schizophrenia 1 (DISC1) is anterogradely transported to the neurite tips, together with Lis1, and functions in neurite extension via suppression of GSK3 beta activity. Then, transported Lis1 is retrogradely transported and functions in cell migration. Here, we show that DISC1-binding zinc finger protein (DBZ), together with DISC1, regulates mouse cortical cell positioning and neurite development in vivo. DBZ hindered Ndel1 phosphorylation at threonine 219 and serine 251. DBZ depletion or expression of a double-phosphorylated mimetic form of Ndel1 impaired the transport of Lis1 and DISC1 to the neurite tips and hampered microtubule elongation. Moreover, application of DISC1 or a GSK3 beta inhibitor rescued the impairments caused by DBZ insufficiency or double-phosphorylated Ndel1 expression. We concluded that DBZ controls cell positioning and neurite development by interfering with Ndel1 from disproportionate phosphorylation, which is critical for appropriate anterograde transport of the DISC1-complex.
  • KOMADA Munekazu; KAWACHI Kota; ITO Saki; HARA Nao; KAWACHI Satoko; IKEDA Yayoi; NAGAO Tetsuji
    Annual Meeting of the Japanese Society of Toxicology The Japanese Society of Toxicology 42 P - 26 2015 
    胎児期あるいは新生児期にアルコールに曝露すると、特徴的な頭部顔面の形成異常や、発達・学習障害、行動異常などを示す胎児アルコール症候群を発症することが知られている。アルコールは妊娠・授乳中にも摂取しやすく、また他の催奇形物質と異なり毒性の閾値が明確でないこと、個人差が大きいことなどから、その危険性や発症機序を明らかにすることは急務である。エタノールの胎児期曝露による頭部顔面の正中部の形成異常はアポトーシスに因ることが示されているが、発達・学習障害や行動異常の原因については不明な点が多い。そこで本研究課題では、高次脳機能の中枢である大脳皮質の形態異常に着目した解析を行った。エタノール曝露モデルマウスとして、妊娠6日から18日（12：00と18：00の2回投与、投与前2時間は絶食）まで25％(w/v)のエタノール0.5、1、2 g/kg体重をICRマウスに強制経口投与し、その胎児・新生児を用いて形態学・行動学的解析を行った。胎児期においては細胞増殖や神経新生に異常が見られた。これらの異常は新生児期に、神経細胞の分布や投射の異常、大脳皮質の層構造の形成異常に繋がっていることが示唆された。さらに、新生児期と成熟期の神経機能の異常を調べるために行動解析を行ったところ、新生児期の振戦が増加し、成熟期においても活動量の亢進が見られた。以上のことから、胎児期のエタノール曝露は大脳皮質の発生において神経新生や細胞増殖に異常を誘発し、組織構築や神経投射に影響を及ぼしていることが示された。また、これらの器質的異常は新生児、成熟個体に対して活動量の亢進といった行動異常の原因となることが明らかになった。しかし、本モデルマウスでは大脳皮質においてアポトーシスの亢進は認められなかったことから、別の発症機序によると考えられる。
  • Munekazu Komada; Saki Itoh; Kota Kawachi; Nao Kagawa; Yayoi Ikeda; Tetsuji Nagao
    TOXICOLOGY ELSEVIER IRELAND LTD 323 51 - 60 0300-483X 2014/09 [Refereed]
     
    The central nervous system is especially susceptible to toxic insults during development. Prenatal administration of bisphenol A (BPA) induces histologic anomalies in the dorsal telencephalon of the embryo. Whether these anomalies affect the morphogenesis and maturation of neuronal function of the newborn neocortex, however, is unknown. To evaluate the neurodevelopmental and behavioral effects of prenatal BPA exposure at 20 and 200 mu g/kg/day in newborn mice, we performed a detailed histologic analysis of the neocortex and tested for the presence of behavioral abnormalities in newborn mice prenatally exposed to BPA using our newly developed behavioral test. Observations of newborn mice prenatally exposed to BPA revealed abnormal neuronal distribution and layer formation, hypoplasia of layer 6b, and abnormal dopaminergic neuronal projections in the neocortex. Further, the newborn mice exhibited hyperactivity. These findings suggest that prenatal BPA exposure induces neurobehavioral toxicity associated with abnormal dopaminergic neuronal projections, and abnormal corticogenesis and lamination. Histologic and behavioral analyses of newborn mice are considered useful for assessing the neurodevelopmental and behavioral toxicity of chemicals. (C) 2014 Elsevier Ireland Ltd. All rights reserved.
  • Hideshi Yagi; Takashi Nagano; Min-Jue Xie; Hiroshi Ikeda; Kazuki Kuroda; Munekazu Komada; Tokuichi Iguchi; Rahman M. Tariqur; Soichi Morikubo; Koichi Noguchi; Kazuyuki Murase; Masaru Okabe; Makoto Sato
    SCIENTIFIC REPORTS NATURE PUBLISHING GROUP 4 6353  2045-2322 2014/09 [Refereed]
     
    Learning and memory depend on morphological and functional changes to neural spines. Non-muscle myosin 2b regulates actin dynamics downstream of long-term potentiation induction. However, the mechanism by which myosin 2b is regulated in the spine has not been fully elucidated. Here, we show that filamin A-interacting protein (FILIP) is involved in the control of neural spine morphology and is limitedly expressed in the brain. FILIP bound near the ATPase domain of non-muscle myosin heavy chain IIb, an essential component of myosin 2b, and modified the function of myosin 2b by interfering with its actin-binding activity. In addition, FILIP altered the subcellular distribution of myosin 2b in spines. Moreover, subunits of the NMDA receptor were differently distributed in FILIP-expressing neurons, and excitation propagation was altered in FILIP-knockout mice. These results indicate that FILIP is a novel, region-specific modulator of myosin 2b.
  • Tetsuji Nagao; Kota Kawachi; Nao Kagawa; Munekazu Komada
    JOURNAL OF TOXICOLOGICAL SCIENCES JAPANESE SOC TOXICOLOGICAL SCIENCES 39 (2) 231 - 235 0388-1350 2014/04 [Refereed]
     
    There have been few neurobehavioral toxicology studies on newborn animals. Thus, we developed a mouse newborn behavioral testing method for evaluating the risk of neurotoxicity of environmental toxicants, by means of determining the newborn's motor activity applying the tare function of an analytical balance. Motor activities including crawling, pivoting, righting or tremors of mouse newborns were evaluated. Tremors of newborns of dams exposed to bisphenol A at 2, 20 or 200 mu g/kg/day on days 5 through 18 of gestation were significantly increased when evaluated on postnatal day 1, as well as those of newborns exposed prenatally to diethylstilbestrol at 0.5 mu g/kg/day. We suggest that our developed testing method may provide a useful addition to neurobehavioral assessment in very young rodents exposed to environmental hormone mimics.
  • Tetsuji Nagao; Nao Kagawa; Munekazu Komada
    JOURNAL OF APPLIED TOXICOLOGY WILEY-BLACKWELL 33 (12) 1514 - 1519 0260-437X 2013/12 [Refereed]
     
    Although there have been a vast number of behavioral toxicology studies carried out on adult mice and rats, there have been few neurobehavioral studies utilizing their newborn animals. Thus, we developed a mouse newborn behavioral testing method for evaluating the risk of neurotoxicity of chemicals, by means of determining the newborn's activity using the tare function of an analytical balance. The unstable weighing values resulting from movement of the newborn on the balance recorded by a personal computer every 0.1s, and the total activities of a newborn from the start time of weighing to individual times of evaluation were calculated. In addition, we confirmed the usefulness of our method by determining the activity of mouse newborns with microcephaly induced by prenatal exposure to a neurotoxicant, methylnitrosourea. Copyright (c) 2012 John Wiley & Sons, Ltd.
  • Tetsuji Nagao; Nao Kagawa; Yoshiaki Saito; Munekazu Komada
    JOURNAL OF APPLIED TOXICOLOGY WILEY-BLACKWELL 33 (11) 1213 - 1221 0260-437X 2013/11 [Refereed]
     
    Placental growth and function are of biological significance in that placental tissue promotes prenatal life and the maintenance of pregnancy. Exposure to synthetic estrogens causes embryonic mortality and placental growth restriction in mice. The aim of the present study was to examine the effects of diethylstilbestrol (DES) on placenta in mice. DES at 1, 5, 10 or 15 mu g kg(-1) day(-1), or 17-estradiol (E-2) at 50 mu g kg(-1) day(-1), was administered orally to ICR mice on days 4 through to 8 of gestation. Expression of ER, ER, ERR or ERR mRNA in the junctional or labyrinth zone of the placentas on day 13 was assessed using RT-PCR, as well as the embrynic mortality, embryonic and placental weight, histological changes of labyrinth and ultrastructural changes of the trophoblast giant cells (TGCs). Embryo mortalities in the DES 10 and 15 mu g kg(-1) day(-1) groups were markedly increased. No significant changes in embryonic and placental weight were observed in any DES- or E-2-exposed groups. Expression of ER mRNA in the junctional zone with male embryos in the 5 mu g kg(-1) day(-1) group was significantly higher than that in the control, whereas expression was not determined in the 15 mu g kg(-1) day(-1) group. Histological observation revealed that the placentas exposed to DES at 10 mu g kg(-1) day(-1) lacked the developing labyrinth. Ultrastructural observation of the TGCs showed poor rough-surfaced endoplasmic reticulum in the DES 10 mu g kg(-1) day(-1) group. The present data suggest that developmental changes induced by DES may be related to interference with the nutrition and oxygen exchange between mother and embryo or decreased protein synthesis, resulting in a high frequency of embryo mortality. Copyright (c) 2012 John Wiley & Sons, Ltd.
  • Min-Jue Xie; Hideshi Yagi; Kazuki Kuroda; Chen-Chi Wang; Munekazu Komada; Hong Zhao; Akira Sakakibara; Takaki Miyata; Koh-Ichi Nagata; Yuichiro Oka; Tokuichi Iguchi; Makoto Sato
    Cerebral Cortex 23 (6) 1410 - 1423 1047-3211 2013/06 [Refereed]
     
    Glia-guided migration (glia-guided locomotion) during radial migration is a characteristic yet unique mode of migration. In this process, the directionality of migration is predetermined by glial processes and not by growth cones. Prior to the initiation of glia-guided migration, migrating neurons transform from multipolar to bipolar, but the molecular mechanisms underlying this multipolar-bipolar transition and the commencement of glia-guided migration are not fully understood. Here, we demonstrate that the multipolar-bipolar transition is not solely a cell autonomous event instead, the interaction of growth cones with glial processes plays an essential role. Time-lapse imaging with lattice assays reveals the importance of vigorously active growth cones in searching for appropriate glial scaffolds, completing the transition, and initiating glia-guided migration. These growth cone activities are regulated by Abl kinase and Cdk5 via WAVE2-Abi2 through the phosphorylation of tyrosine 150 and serine 137 of WAVE2. Neurons that do not display such growth cone activities are mispositioned in a more superficial location in the neocortex, suggesting the significance of growth cones for the final location of the neurons. This process occurs in spite of the "inside-out" principle in which later-born neurons are situated more superficially. © 2012 The Author.
  • Komada M; Iguchi T; Takeda T; Ishibashi M; Sato M
    Neuroscience letters 547 87 - 91 0304-3940 2013/06 [Refereed]
     
    Translocation of the Smoothened to the cell membrane is critical for sonic hedgehog activity. However, the biological importance of Smoothened itself has not been fully studied. To address this issue, we disabled Smoothened specifically in the dorsal telencephalon. Birth-date analysis and layer marker expression patterns revealed the slightly impaired development of the superficial layer neurons in the embryos of Emx1-Cre; Smoothened(fl/-) conditional knockout mice. Further analysis of the mutant embryos revealed a decrease in the number of intermediate progenitor cells. In the knockout mice, the expression of cyclin D2, but not cyclin D1 or cyclin E, was reduced in the dorsal telencephalon. In addition, the projections of dopaminergic neurons were affected during development, and the number of activated astrocytes was increased in the neocortex of the mutant mice. Our data suggest that Smoothened signaling, acting through cyclin D2, is critical for the proper development and maturation of the neocortex. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.
  • Munekazu Komada
    CONGENITAL ANOMALIES WILEY-BLACKWELL 52 (2) 72 - 77 0914-3505 2012/06 [Refereed]
     
    Sonic hedgehog (Shh) acts as a morphogen in normal development of various vertebrate tissues and organs. Shh signaling is essential for patterning and cell-fate specification, particularly in the central nervous system. Shh signaling plays different roles depending on its concentration, area, and timing of exposure. During the development of the neocortex, a low level of Shh is expressed in the neural stem/progenitor cells as well as in mature neurons in the dorsal telencephalon. Shh signaling in neocortex development has been shown to regulate cell cycle kinetics of radial glial cells and intermediate progenitor cells, thereby maintaining the proliferation, survival and differentiation of neurons in the neocortex. During the development of the telencephalon, endogenous Shh signaling is involved in the transition of slow-cycling neural stem cells to fast-cycling neural progenitor cells. It seems that high-level Shh signaling in the ventral telencephalon is essential for ventral specification, while low-level Shh signaling in the dorsal telencephalon plays important roles in the fine-tuning of cell cycle kinetics. The Shh levels and multiple functions of Shh signaling are important for proper corticogenesis in the developing brain. The present paper discusses the roles of Shh signaling in the proliferation and differentiation of neural stem/progenitor cells.
  • Munekazu Komada; Yasuko Asai; Mina Morii; Michie Matsuki; Makoto Sato; Tetsuji Nagao
    TOXICOLOGY ELSEVIER IRELAND LTD 295 (1-3) 31 - 38 0300-483X 2012/05 [Refereed]
     
    Bisphenol A (BPA), an endocrine-disruptor, is widely used in the production of plastics and resins. Human perinatal exposure to this chemical has been proposed to be a potential risk to public health. Animal studies indicate that postnatal exposure to BPA may affect neocortex development in embryos by accelerated neurogenesis and causing neuronal migration defects. The detailed phenotypes and pathogenetic mechanisms, especially with regard to the proliferation and differentiation of neural stem/progenitor cells, however, have not been clarified. C57BL/6J pregnant mice were orally administered BPA at 200 mu g/kg from embryonic day (E) 8.5 to 13.5, and the fetuses were observed histologically at E14.5. To clarify the histological changes, especially in terms of neurogenesis, proliferation and cell cycle, we performed histological analysis using specific markers of neurons/neural stem cells and cell cycle-specific labeling experiments using thymidine-analog substances. Cortical plate was hyperplastic and the number of neural stem/progenitor cells was decreased after the exposure to BPA. In particular, the maternal BPA oral dosing related to the effects on intermediate progenitor cells (IPCs, neural progenitor cells) in the subventricular zone (SVZ) of dorsal telencephalon. Exposure to BPA associated the promotion of the cell cycle exit in radial glial cells (RGCs, neural stem cells) and IPCs, and decreased the proliferation resulting from the prolong cell cycle length of IPCs in the SVZ. Our data show that maternal oral exposure to BPA related to the disruption of the cell cycle in IPCs and the effects of neurogenesis in the developing neocortex. (C) 2012 Elsevier Ireland Ltd. All rights reserved.
  • Munekazu Komada; Tokuichi Iguchi; Kazuki Kuroda; Min-jue Xie; Hideshi Yagi; Makoto Sato
    NEUROSCIENCE RESEARCH ELSEVIER IRELAND LTD 71 E229 - E229 0168-0102 2011 [Refereed]
  • Min-Jue Xie; Hideshi Yagi; Kazuki Kuroda; Munekazu Komada; Tokuichi Iguchi; Makoto Sato
    NEUROSCIENCE RESEARCH ELSEVIER IRELAND LTD 71 E129 - E129 0168-0102 2011 [Refereed]
  • Hideshi Yagi; Min-Jue Xie; Hiroshi Ikeda; Munekazu Komada; Tokuichi Iguchi; Kazuki Kuroda; Masaru Okabe; Makoto Sato
    NEUROSCIENCE RESEARCH ELSEVIER IRELAND LTD 71 E344 - E345 0168-0102 2011 [Refereed]
  • Yukiyasu Sato; Yukiko Izumi; Katsura Minegishi; Munekazu Komada; Shigehito Yamada; Kazuyo Kakui; Keiji Tatsumi; Yoshiki Mikami; Hiroshi Fujiwara; Ikuo Konishi
    FETAL DIAGNOSIS AND THERAPY KARGER 29 (4) 325 - 330 1015-3837 2011 [Refereed]
     
    We here describe a case of congenital leukemia that ended in intrauterine fetal demise at 30 weeks of gestation. Acute enlargement of the fetal trunk, elevated pulsatility index of the umbilical artery with concomitant decline of pulsatility index of the middle cerebral artery, pleural effusion, and polyhydramnios preceded the fetal death. Diagnosis of congenital myeloid leukemia was suggested by microscopic examination of the placental tissue, revealing immature myeloid precursors filling the lumina of fetal vessels in the umbilical cord and chorionic villi. Extensive vascular involvement of the placenta by leukemic cells was considered to be a primary cause of the fetal death. Copyright (C) 2011 S. Karger AG, Basel
  • Saitsu H; Tohyama J; Kumada T; Egawa K; Hamada K; Okada I; Mizuguchi T; Osaka H; Miyata R; Furukawa T; Haginoya K; Hoshino H; Goto T; Hachiya Y; Yamagata T; Saitoh S; Nagai T; Nishiyama K; Nishimura A; Miyake N; Komada M; Hayashi K; Hirai S; Ogata K; Kato M; Fukuda A; Matsumoto N
    American journal of human genetics 86 (6) 881 - 891 0002-9297 2010/06 [Refereed]
     
    A de novo 9q33.3-q34.11 microdeletion involving STXBP1 has been found in one of four individuals (group A) with early-onset West syndrome, severe hypomyelination, poor visual attention, and developmental delay. Although haploinsufficiency of STXBP1 was involved in early infantile epileptic encephalopathy in a previous different cohort study (group B), no mutations of STXBP1 were found in two of the remaining three subjects of group A (one was unavailable). We assumed that another gene within the deletion might contribute to the phenotype of group A. SPTAN1 encoding alpha-II spectrin, which is essential for proper myelination in zebrafish, turned out to be deleted. In two subjects, an in-frame 3 bp deletion and a 6 bp duplication in SPTAN1 were found at the initial nucleation site of the alpha/beta spectrin heterodimer. SPTAN1 was further screened in six unrelated individuals with WS and hypomyelination, but no mutations were found. Recombinant mutant (mut) and wild-type (WT) alpha-II spectrin could assemble heterodimers with beta-II spectrin, but alpha-II (mut)/beta-II spectrin heterodimers were thermolabile compared with the alpha-II (WT)/beta-II heterodimers. Transient expression in mouse cortical neurons revealed aggregation of alpha-II (mut)/beta-II and alpha-II (mut)/beta-III spectrin heterodimers, which was also observed in lymphoblastoid cells from two subjects with in-frame mutations. Clustering of ankyrinG and voltage-gated sodium channels at axon initial segment (AIS) was disturbed in relation to the aggregates, together with an elevated action potential threshold. These findings suggest that pathological aggregation of alpha/beta spectrin heterodimers and abnormal AIS integrity resulting from SPTAN1 mutations were involved in pathogenesis of infantile epilepsy.
  • Munekazu Komada; Fusako Fujiyama; Shigehito Yamada; Kohei Shiota; Tetsuji Nagao
    BIRTH DEFECTS RESEARCH PART B-DEVELOPMENTAL AND REPRODUCTIVE TOXICOLOGY WILEY-LISS 89 (3) 213 - 222 1542-9733 2010/06 [Refereed]
     
    BACKGROUND: Prenatal exposure to methylnitrosourea (MNU), an alkylating agent, induces microcephaly in mice. However, its pathogenetic mechanism has not been clarified, especially that in the development of the cerebral cortex. METHODS: ICR mice were treated with MNU at 10 mg/kg intraperitoneally on day 13.5 or 15.5 of gestation, and the embryos were observed histologically 24 hr after treatment with MNU or at term. To clarify the pathogenesis of microcephaly and histological changes, especially apoptosis, neurogenesis, and neural migration/positioning, we performed histological analysis employing a cell-specific labeling experiment using thymidine-like substances (BrdU, CldU, and IdU) and markers of neurons/neural stem cells. RESULTS: Histological abnormalities of the dorsal telencephalon, and the excessive cell death of proliferative neural progenitor/stem cells were noted in the MNU-treated embryos. The highest frequencies of cell death occurred at 36 hr after MNU treatment, and little or no neurogenesis was observed in the ventricular zone of the dorsal telencephalon. Abnormality of the radial migration was caused by the reduction of radial fibers in the radial glias. Birth-date analysis revealed the abnormal positioning of neurons and aberrant lamination of the cerebral cortex. CONCLUSIONS: Our data suggest that prenatal exposure to MNU induces the excessive cell death of neural precursor/stem cells, and the defective development of the cerebral cortex, resulting in microcephalic abnormalities. Birth Defects Res (Part B) 89:213-222, 2010. (C) 2010 Wiley-Liss,
  • Hisataka Tanaka; Jianmei Ma; Kenji F. Tanaka; Keizo Takao; Munekazu Komada; Koichi Tanda; Ayaka Suzuki; Tomoko Ishibashi; Hiroko Baba; Tadashi Isa; Ryuichi Shigemoto; Katsuhiko Ono; Tsuyoshi Miyakawa; Kazuhiro Ikenaka
    JOURNAL OF NEUROSCIENCE SOC NEUROSCIENCE 29 (26) 8363 - 8371 0270-6474 2009/07 [Refereed]
     
    Conduction velocity (CV) of myelinated axons has been shown to be regulated by oligodendrocytes even after myelination has been completed. However, how myelinating oligodendrocytes regulate CV, and what the significance of this regulation is for normal brain function remain unknown. To address these questions, we analyzed a transgenic mouse line harboring extra copies of the myelin proteolipid protein 1 (plp1) gene (plp1(tg/-) mice) at 2 months of age. At this stage, the plp1(tg/-) mice have an unaffected myelin structure with a normally appearing ion channel distribution, but the CV in all axonal tracts tested in the CNS is greatly reduced. We also found decreased axonal diameters and slightly abnormal paranodal structures, both of which can be a cause for the reduced CV. Interestingly the plp1(tg/-) mice showed altered anxiety-like behaviors, reduced prepulse inhibitions, spatial learning deficits and working memory deficit, all of which are schizophrenia-related behaviors. Our results implicate that abnormalities in the neuron-glia interactions at the paranodal junctions can result in reduced CV in the CNS, which then induces behavioral abnormalities related to schizophrenia.
  • Takashi Miura; Dirk Hartmann; Masato Kinboshi; Munekazu Komada; Makoto Ishibashi; Kohei Shiota
    MECHANISMS OF DEVELOPMENT ELSEVIER SCIENCE BV 126 (3-4) 160 - 172 0925-4773 2009/03 [Refereed]
     
    The developing avian lung is formed mainly by branching morphogenesis, but there is also a unique cystic structure, the air sac, in the ventral region. It has been shown that mesenchymal tissue is responsible for the differential development of a cystic or branched structure, and that the transcription factor Hoxb may be involved in determining this regional difference. We have previously developed two scenarios for branch-cyst transition, both experimentally and theoretically: increased production or increased diffusion of FGF. The aim of the present study was to discover whether one of these scenarios actually operates in the ventral region of the chick lung. We found that the FGF10 level was lower while the diffusion of FGF10 was more rapid in the ventral lung, indicating that the second scenario is more plausible. There are two possibilities as to why the diffusion of FGF10 differs between the two regions: (1) diffusion is facilitated by the looser tissue organisation of the ventral lung mesenchyme; (2) stronger expression of heparan sulphate proteoglycan ( HSPG) in the dorsal lung traps FGF and decreases the effective diffusion coefficient. Mathematical analysis showed that the dorsal-ventral difference in the amount of HSPG is not sufficient to generate the observed difference in pattern, indicating that both extracellular matrix and tissue architecture play a role in this system. These results suggest that the regional cystic-branched difference within the developing chick lung results from a difference in the rate of diffusion of morphogen between the ventral and dorsal regions due to differential levels of HSPG and a different mesenchymal structure. (C) 2008 Elsevier Ireland Ltd. All rights reserved.
  • Munekazu Komada; Keizo Takao; Tsuyoshi Miyakawa
    Journal of visualized experiments : JoVE 22 (22) 2008/12 [Refereed]
     
    Although the mouse genome is now completely sequenced, the functions of most of the genes expressed in the brain are not known. The influence of a given gene on a specific behavior can be determined by behavioral analysis of mutant mice. If a target gene is expressed in the brain, behavioral phenotype of the mutant mice could elucidate the genetic mechanism of normal behaviors. The elevated plus maze test is one of the most widely used tests for measuring anxiety-like behavior. The test is based on the natural aversion of mice for open and elevated areas, as well as on their natural spontaneous exploratory behavior in novel environments. The apparatus consists of open arms and closed arms, crossed in the middle perpendicularly to each other, and a center area. Mice are given access to all of the arms and are allowed to move freely between them. The number of entries into the open arms and the time spent in the open arms are used as indices of open space-induced anxiety in mice. Unfortunately, the procedural differences that exist between laboratories make it difficult to duplicate and compare results among laboratories. Here, we present a detailed movie demonstrating our protocol for the elevated plus maze test. In our laboratory, we have assessed more than 90 strains of mutant mice using the protocol shown in the movie. These data will be disclosed as a part of a public database that we are now constructing. Visualization of the protocol will promote better understanding of the details of the entire experimental procedure, allowing for standardization of the protocols used in different laboratories and comparisons of the behavioral phenotypes of various strains of mutant mice assessed using this test.
  • Munekazu Komada; Hirotomo Saitsu; Masato Kinboshi; Takashi Miura; Kohei Shiota; Makoto Ishibashi
    DEVELOPMENT COMPANY OF BIOLOGISTS LTD 135 (16) 2717 - 2727 0950-1991 2008/08 [Refereed]
     
    Sonic hedgehog (Shh) function is essential for patterning and cell fate specification, particularly in ventral regions of the central nervous system. It is also a crucial mitogen for cerebellar granule neuron precursors and is important in maintenance of the stem cell niche in the postnatal telencephalon. Although it has been reported that Shh is expressed in the developing dorsal telencephalon, functions of Shh in this region are unclear, and detailed characterization of Shh mRNA transcripts in situ has not been demonstrated. To clarify the roles of Shh signaling in dorsal pallium ( neocortex primordium) development, we have knocked out the Shh and Smo genes specifically in the early developing dorsal telencephalon by using Emx1(cre) mice. The mutants showed a smaller dorsal telencephalon at E18.5, which was caused by cell cycle kinetics defects of the neural progenitor/stem cells. The cell cycle length of the progenitor/stem cells was prolonged, and the number of cycle-exiting cells and neurogenesis were decreased. Birth- date analysis revealed abnormal positioning of neurons in the mutants. The characteristics of the subventricular zone, ventricular zone and subplate cells were also affected. Weak immunoreactivity of Shh was detected in the dorsal telencephalon of wild types. Reduced Shh immunoreactivity in mutant dorsal telencephalons supports the above phenotypes. Our data indicate that Shh signaling plays an important role in development of the neocortex.
  • Munekazu Komada; Hirotomo Saitsu; Kohei Shiota; Makoto Ishibashi
    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS ACADEMIC PRESS INC ELSEVIER SCIENCE 369 (2) 350 - 356 0006-291X 2008/05 [Refereed]
     
    Fibroblast growth factor 15 (Fgf15) is expressed in the medial region of diencephalon and midbrain by the seven-somite stage. In the previous studies, we showed that Sonic hedgehog signaling through Gli protein is required for Fgf15 expression in this region. The Fgf15 expression domain overlapped with that of Gli2 and the Gli-binding site (GliBs) is located in the 3.6-kb 5'-flanking enhancer/promoter region of the Fgf15 gene. In this study, we identified the two additional Gli-binding sites in row, called Gli-responsive elements (GliREs). Chromatin immunoprecipitation assay indicated that Gli2 directly binds to GliREs. The results from luciferase assays indicated that the Gli2 activator form binds to the GliBS and that the Gli2 repressor form binds to the GliREs. These findings suggest that the repressor form of Gli2 preferentially binds to the GliREs to control Fgf15 expression. (c) 2008 Elsevier Inc. All rights reserved.
  • Kohei Shiota; Shigehito Yamada; Munekazu Komada; Makoto Ishibashi
    AMERICAN JOURNAL OF MEDICAL GENETICS PART A WILEY-LISS 143A (24) 3079 - 3087 1552-4825 2007/12 [Refereed]
     
    Holoprosencephaly (HPE) is a malformation of the human brain caused primarily by incomplete division of the prosencephalon into two halves and is often associated with various facial anomalies. Although HPE is rather rare in newborns (1/10,000-15,000 births), it is frequently encountered in therapeutic abortuses (>1/250). To date, nine gene mutations responsible for human HPE have been identified, but the pathogenetic mechanisms of the craniofacial anomalies in HPE have just begun to be understood. Here, we summarize our studies on human embryos with HPE and discuss the embryogenesis and the underlying molecular mechanisms of HPE malformations under the following headings: pathology, pathogenesis, and critical period of development. (C) 2007 Wiley-Liss, Inc.
  • Daisuke Higashiyama; Hirotomo Saitsu; Munekazu Komada; Toshiya Takigawa; Makoto Ishibashi; Kohei Shiota
    BIRTH DEFECTS RESEARCH PART A-CLINICAL AND MOLECULAR TERATOLOGY WILEY-LISS 79 (7) 513 - 523 1542-0752 2007/07 [Refereed]
     
    Background Prenatal exposure to ethanol induces holoprosencephalic malformations in both humans and laboratory animals. However, its teratogenic window for inducing holoprosencephaly is narrow, and the teratogenic mechanism is not well understood. In the present study, we examined the morphological changes in the craniofacial structures of mouse embryos/fetuses at intervals following ethanol treatment and evaluated gene expression patterns in the embryos. Methods: Pregnant C57BL/6J mice were given two doses of ethanol (30 mg/kg in total) on the morning (7:00 and 11:00 AM) of day 7. The fetuses were observed at E10.5 and E15.5 grossly and/or histologically. The expression of Shh and Nkx2.1 gene transcripts was examined at E8.5 by in situ hybridization. Results: Gross and histological abnormalities of the brain and face were found in ethanol-exposed fetuses, and their midline structures were most frequently affected. The midline commissural fibers were often lacking in ethanol-exposed fetuses, even in those cases without external gross malformations. In situ hybridization revealed down-regulation of Shh and Nkx2.1 genes in ethanol-exposed embryos. Conclusions: The results indicate that ethanol may perturb the expression of some developmental genes at a critical stage of embryonic development and induce holoprosencephaly and other midline craniofacial malformations, including histological brain abnormalities.
  • Makoto Ishibashi; Hirotomo Saitsu; Munekazu Komada; Kohei Shiota
    Anatomical science international 1 80 (1) 30 - 6 1447-6959 2005/03 [Refereed]
     
    The vertebrate brain is a complex and highly organized structure with numerous neurons and glial cells. During development, undifferentiated progenitor cells proliferate from neural stem/precursor cells and gradually restrict their fates according to their environment. Differentiated cells are arranged precisely to accomplish their function and to maintain integrity as a whole brain. In this respect, cells must receive signals to know where and when they determine their fates. Secreted and membrane molecules convey the information between cells. The secreted glycoprotein Sonic hedgehog (Shh) is one of such signaling molecules. Sonic hedgehog is widely known to specify ventral neuronal types according to the concentration of Shh, whereas differentiation of dorsal neurons is largely independent of Shh. However, in the diencephalon and midbrain, dorsal parts are also affected in Shh-mutant embryos. Detailed analysis demonstrated that Shh signaling indirectly regulates the growth of the dorsal tissue in these regions. One of the fibroblast growth factor (FGF) members, namely FGF15, has been reported to be downstream to Shh signaling in the mouse embryonic brain. Luciferase assays and transgenic analysis revealed that the Fgf15 gene is a direct target of Shh. Downregulation of Tcf4 and upregulation of Bmp4 in Shh mutants suggest that Wnt and BMP signals from the dorsal midline are also involved in the dorsal brain phenotype. These data suggest the coordinating role of the Shh-FGF15-Wnt/BMP signaling cascade between the ventral and dorsal parts of the brain.
  • H Saitsu; M Komada; M Suzuki; R Nakayama; J Motoyama; K Shiota; M Ishibashi
    DEVELOPMENTAL DYNAMICS WILEY-LISS 232 (2) 282 - 292 1058-8388 2005/02 [Refereed]
     
    Sonic hedgehog (Shh) is a secreted molecule that is thought to regulate tissue growth and patterning in vertebrate embryos. Although it has been reported that Gli transcription factors mediate Shh signaling to the nucleus, little is known about developmental target genes of Gli. In the previous genetic study, we showed that Shh is required for Fgt75 expression in the diencephalon and midbrain. Here, we examined whether Fgt75 is a direct target of Shh signaling through Gli. Shh was expressed in the midline cells and Fgt75 in the medial region of the diencephalon/midbrain by the seven-somite stage. The Fgt75 expression domain coincided with that of Gli1 and overlapped with that of Gli2 at this stage. Fgt75 expression in the diencephalon/midbrain was greatly reduced in the seven-somite Shh mutant embryos. Transgenic analysis showed that the 3.6-kb 5'-flanking region of the Fgt75 gene is sufficient for induction of Fgt75 in the medial/ventral diencephalon/midbrain. Luciferase assay showed that the 3.6-kb Fgt75 enhancer/promoter was activated by Gli2. A Gli-binding site was located 1 kb upstream of the transcription start site and was required for expression in the medial/ventral diencephalon/midbrain in transgenic embryos and for activation in luciferase assay. These findings indicate that Fgt75 is directly regulated by Shh signaling through Gli proteins. (C) 2004 Wiley-Liss, Inc.

Books etc

  • Diagnosis, Management and Modeling of Neurodevelopmental Disorders
    Komada Munekazu (Joint workChapter 3: Chemical substances affecting neurodevelopment)Elsevier 2021/05
  • 安東, 賢太郎; 橋本, 敬太郎; 藤森, 観之助 エル・アイ・シー 2009/09 9784900487468 432p

MISC

  • Prenatal exposure to valproic acid induces morphological and functional abnormalities of the neocortex with neuro-inflammation
    駒田致和; 松井拓磨  第48回日本先天異常学会学術集会 抄録集  2021/08  [Refereed]
  • Abnormal neurogenesis due to prenatal exposure to valproic acid affects neurodevelopment
    Komada Munekazu; Matsui Takuma  The 44th Annual Meeting of the Japan Neuroscience Society  2021/07  [Refereed]
  • バルプロ酸の胎児期曝露が誘発するミクログリアの異常が大脳皮質の発生・発達に及ぼす影響
    駒田致和; 松井拓磨  第48回日本毒性学会学術年会 抄録集  2021/06  [Refereed]
  • 胎仔期低用量Bisphenol A曝露が視床下部形成に及ぼす影響
    高橋 美文; 駒田 致和; 田渕 雅子; 宮澤 健; 池田 やよい; 後藤 滋巳  日本矯正歯科学会大会プログラム・抄録集  76回-  176  -176  2017/10
  • 猪口徳一; 猪口徳一; 岡本昌之; 岡本昌之; 服部剛志; 服部剛志; 松崎伸介; 松崎伸介; 駒田致和; 謝敏カク; 謝敏カク; 八木秀司; 八木秀司; 広常真治; 遠山正彌; 遠山正彌; 佐藤真; 佐藤真; 佐藤真; 佐藤真  日本解剖学会総会・全国学術集会講演プログラム・抄録集  121st-  98  2016  [Refereed][Invited]
  • DISC1-binding zinc finger protein (DBZ) regulates cortical cell positioning and neurite elongation through control of Ndel1 dual-phosphorylation
    Iguchi T; Okamoto M; Hattori T; Matsuzaki S; Koyama Y; Taniguchi M; Komada M; Xie M; Yagi H; Shimizu S; Omi M; Katayama T; Ito A; Hirotsune S; Tohyama M; Sato M  Neuroscience 2015, SfN's 45th annual meeting  2015/10  [Refereed]
  • 大脳皮質形成と棘突起形態に対するFILIPの役割(Filip play a role in cortical development and spine morphology)
    八木 秀司; 謝 敏カク; 池田 弘; 駒田 致和; 猪口 徳一; 黒田 一樹; 岡部 勝; 佐藤 真  神経化学  50-  (2-3)  191  -191  2011/09
  • 駒田致和; 猪口徳一; 黒田一樹; 謝敏かく; 八木秀司; 佐藤真  日本先天異常学会学術集会プログラム・抄録集  51st-  63  2011/07
  • ニトロソ尿素の胎児期曝露によって誘発されるマウス小頭症発症機序
    駒田 致和; 藤山 総子; 山田 重人; 塩田 浩平; 長尾 哲二  解剖学雑誌  86-  (2)  55  -55  2011/06
  • M. Komada; F. Fujiyama; S. Yamada; K. Shiota; T. Nagao  BIRTH DEFECTS RESEARCH PART A-CLINICAL AND MOLECULAR TERATOLOGY  88-  (5)  381  -381  2010/05
  • 位相差コントラストX線CTを用いた胚イメージング(Embryo Imaging using phase-contrast X-ray computed tomography)
    山田 重人; 米山 明男; 武田 徹; 峰岸 かつら; 土屋 真衣子; 駒田 致和; 塩田 浩平  解剖学雑誌  85-  (Suppl.)  135  -135  2010/03
  • ホルマリンで長期保存したヒト胚からのDNA抽出(Extraction of DNA from human embryos after long-term preservation in formalin solution)
    峰岸 かつら; 駒田 致和; 土屋 真衣子; 塩田 浩平; 山田 重人  解剖学雑誌  85-  (Suppl.)  135  -135  2010/03
  • ニトロソ尿素投与によって誘発される神経幹細胞細胞死とマウス小頭症の発症機序
    駒田 致和; 藤山 総子; 山田 重人; 塩田 浩平; 長尾 哲二  解剖学雑誌  85-  (Suppl.)  137  -137  2010/03
  • KOMADA Munekazu; TAKAO Keizo; NAKANISHI Kazuo; MIYAKAWA Tsuyoshi  Journal of Information Processing and Management  52-  (2)  69  -76  2009
  • Keizo Takao; Katsunori Kobayashi; Hideo Hagihara; Koji Ohira; Nobuyuki Yamasaki; Munekazu Komada; Keiko Toyama; Tsuyoshi Takagi; Shunsuke Ishii; Tsuyoshi Miyakawa  JOURNAL OF PHYSIOLOGICAL SCIENCES  59-  519  -519  2009
  • Makoto Ishibashi; Munekazu Komada; Hirotomo Saitsu; Masato Kinoshi; Takashi Miura; Kohei Shiota  NEUROSCIENCE RESEARCH  61-  S227  -S227  2008
  • Munekazu Komada; Hirotomo Saitsu; Kohei Shiota; Makoto Ishibashi  NEUROSCIENCE RESEARCH  58-  S82  -S82  2007
  • M Ishibashi; H Saitsu; M Komada; M Suzuki; R Nakayama; J Motoyama; K Shiota  FASEB JOURNAL  20-  (5)  A878  -A878  2006/03

Research Grants & Projects

  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2022/04 -2025/03 
    Author : 駒田 致和
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2017/04 -2021/03 
    Author : Komada Munekazu
     
    The central nerve system during the prenatal period, in which cells proliferate, neurognesis, and neuronal migration, is highly sensitive to environmental factors such as chemical substances, stress exposure, and infectious diseases. Effects on cell dynamics such as neurogensis, maturation, and neuronal projection during this period can cause congenital malformations and brain dysfunctio0n. We focused on abnormal activation of microglia and inflammation in the developing brain. These have been shown to be widespread phenomena due to prenatal exposure to various chemicals and stresses, as well as infectious diseases. In other words, it was shown that morphogenesis and functional maturation of the cerebral cortex and hippocampal dentate gyrus may be hindered by inflammation in the brain caused by various environmental factors, which may cause congenital malformations and developmental disorders.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2017/04 -2020/03 
    Author : NAGAO Tetsuji
     
    Microglia are the immune cells of the central nervous system (CNS), play a critical role in its development and are involved in neural stem cells proliferation, differentiation, and migration in the developing CNS. To evaluate the microglial morphology and the gene expression of pro-inflammatory cytokines in the neocortex, mice were exposed to BPA or VPA at the critical period. Offspring exposed showed an increased number of amoeboid-type microglia, a microglial differentiation disruption, and an abnormal expression of genes encoding pro-inflammatory factors. The abnormalities induced by VPA exposure were ameliorated by co-treatment with anti-inflammatory drug. The findings suggest that the cytoarchitecture of the neocortex can be restored via treatment with anti-inflammatory agents that target microglial abnormalities and neuroinflammation. Anti-inflammatory therapeutics may provide a novel preventive approach for the abnormalities after the exposure to chemicals.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2014/04 -2017/03 
    Author : Komada Munekazu
     
    Estrogen receptors express in the neurons and microglia in the brain and regulate their activity. Neurosteroids are converted by aromatase and are involved in the development and maturation of the brain. In the study, we showed that SF-1, regulated the expression of estrogen-producing enzyme, were expressed in the neocortex and the brain derived estrogen controlled the proliferation, differentiation, and migration of neurons. In addition, toxicity evaluation by the prenatal exposure of estrogenic chemical substances resulted in the abnormalities in the hypothalamus construction, brain-inflammation, and increase of microglia. We suggest that estrogen signaling act on the neurons and microglia, and contribute to the proper development of brain.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2012/04 -2014/03 
    Author : KOMADA Munekazu
     
    The neocortex comprises several neuronal subtypes and neural glial cells. Differentiation of these cells is regulated by various factors during corticogenesis. In this study, to confirm the mechanism of corticogenesis controlled by the morphogen Hedgehog (HH) signaling, we established conditional knockout (cKO) mice in which the expression of Smo, an HH-signaling mediator, was inhibited in the dorsal telencephalon during development. HH signaling coordinates neurogenesis and cell cycle kinetics via its regulation of cyclin D2 expression. In Smo cKO mice, layer 6b exhibited hypoplasticity with decreased dopaminergic neuronal projections in the prefrontal cortex. These findings suggest that the histologic anomalies in the developing neocortex induced neuronal network abnormalities.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2011 -2013 
    Author : XIE Min-Jue; SATO Makoto; KURODA Kazuki; IGUCHI Tokuichi; KOMADA Munekazu
     
    Synapse function and plasticity depend on the morphology of dendritic spine. Here, we report that Phldb2 (pleckstrin homology-like domain, family B, member 2, LL5beta), one binding partner for a well-known actin-cross-linking protein Filamin A, works as a positive regulator of spine maturation. We generated LL5beta knockout mice and found that a proportion of immature spines (filopodia and thin spines) increased in the hippocampus in vivo, which is consistent with our previous observations with LL5beta knocked-down cultured hippocampal neurons. Next, we asked whether or not LL5beta is involved in synaptic plasticity. We observed that NMDA-induced AMPA receptor endocytosis and low-frequency stimulation-induced long-term depression were blocked in hippocampal neurons of the LL5beta knockout mice. Therefore, it is likely that LL5beta plays an important role for the synaptic plasticity and the maturation of dendritic spines.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2011 -2013 
    Author : YAGI Hideshi; SATO Makoto; KURODA Kazuki; KOMADA Munekazu
     
    FILIP has a role in the development of central nervous system through the binding of filamin A that is one of the actin-binding proteins. We investigated the additional function of FILIP on the neuronal morphology in this study. We observed that the expression of FILIP was observed in the limited region of the adult brain. We found that FILIP bound to one of the non-muscle type myosin and altered the subcellular distribution of it. We disclosed that FILIP influenced on the morphology of the excitatory neurons. Our findings suggested that FILIP altered the morphology of neurons through the binding of the myosin. These results indicate that FILIP regulated actomyosin dynamics that have a role on the neuronal morphology.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2011 -2012 
    Author : SATO Makoto; KURODA Kazuki; KOMADA Munekazu
     
    （１） Cortical neurons that had been transfected with Ptf1a expressing vector migrated tangentially into the cortex, of which migratory behavior is typical for GABAergic neurons. （２）Ptf1a expression did not result in transformation of glutamatergic neurons into GABAergic neurons; no specific GABAergic neuronal markers were newly expressed in glutamatergic neurons by Ptf1a expression. （３） We collected RNAs from Ptf1a expressed neurons and searched for any Ptf1a-induced genes, then we identified several candidate genes.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2010 -2011 
    Author : KOMADA Munekazu
     
    Normal morphogenesis of the mammalian cerebral cortex requires orchestration of the proliferation and differentiation of the appropriate number of cells at the appropriate developmental period. Several lines of studies demonstrated that neural stem cells(radial glias : RGs) and neural precursor cells(Intermediate progenitor cells : IPCs) locate in the developing dorsal telencephalon. In particular, IPCs have important roles in the lamination of cerebral cortex layers II and III. We previously reported that Hedgehog(Hh) signaling in the dorsal telencephalon maintains the proliferat ion, survival, and differentiation of RGs and IPCs(Komada et al., 2008). The findings of the present study suggest that Hh signaling controls cell cycle length and regulates the transition from RG to IPCs or neurons and from IPCs to neurons at embryonic day 16. 5 in mice. In the primate cerebral cortex, layers II and III are highly developed and these layers are generated from neurons produced from IPCs. Elucidation of this mechanism is likely to contribute to a better understanding of the constitution of higher brain functions and the pathogenesis of mental disorders.

Teaching Experience

  • Environmental chemical experimentEnvironmental chemical experiment Kindai University

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