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Ogiwara Katsueki

Faculty of Science　Biological Sciences　Reproductive and Developmental BiologyAssociate Professor

Researcher basic information

■ Degree
  • 博士（理学）, 北海道大学
■ URL
researchmap URLホームページURL■ Various IDs
Researcher number
  • 00422006
J-Global ID■ Research Keywords and Fields
Research Keyword
  • ovulation
  • ovary
  • mouse
  • protease
  • medaka
  • transgenic
  • reproduction
  • RNAi
Research Field
  • Life Science, Morphology and anatomical structure
■ Educational Organization

Career

■ Career
Career
  • Oct. 2017 - Present
    Hokkaido University, Faculty of science, Associate professor
  • Apr. 2008 - Sep. 2017
    Graduate school of science, Hokkaido university, Assistant Professor

Research activity information

■ Papers
■ Other Activities and Achievements
■ Syllabus
  • 生命システム科学基礎論, 2024年, 修士課程, 生命科学院
  • 生殖発生機構学特論, 2024年, 修士課程, 生命科学院
  • 細胞生物学概論, 2024年, 学士課程, 理学部
  • 科学・技術の世界（1単位）, 2024年, 学士課程, 全学教育
  • 一般教育演習(ﾌﾚｯｼｭﾏﾝｾﾐﾅｰ), 2024年, 学士課程, 全学教育
  • 生物学Ⅱ, 2024年, 学士課程, 全学教育
  • 自然科学実験, 2024年, 学士課程, 全学教育
  • 基礎生化学実習, 2024年, 学士課程, 理学部
  • 基礎生化学実習, 2024年, 学士課程, 理学部
  • 生殖発生生物学Ⅱ, 2024年, 学士課程, 理学部
  • 基礎形態学実習, 2024年, 学士課程, 理学部
  • 基礎形態学実習, 2024年, 学士課程, 理学部
■ Research Themes
  • アクチビン・インヒビン・エストラジオール経路は濾胞閉鎖を制御するか？
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Apr. 2021 - Mar. 2024
    荻原 克益
    本研究は、マウス濾胞選択の分子機構解明を目指した研究課題である。何らかの刺激により成長を開始した原始濾胞のうち、大部分は成長途中でアポトーシスにより死滅してしまう。そして、生き残った濾胞のみが成熟し排卵される。この様に死滅する濾胞と生き残り排卵される濾胞を選択する過程が、「濾胞選択」である。濾胞選択に関わる数多くの研究報告があるにもかかわらず、今なお、その詳細な分子機構は解明されていない。一般的な過排卵誘導法（PMSG/hCG等）で20-30個程度の卵が排卵されるが、特殊な薬剤を用いた排卵誘導法では100個程度の卵が排卵されることが知られている。そこで、本研究ではこの薬剤を用いて濾胞選択の研究を展開している。これまでの研究結果から、その薬剤が濾胞選択（アポトーシス）を抑制すること、その薬剤により卵巣内における活性型アクチビン量が有意に増加すること、また、血中および卵巣内エスタジオール量が有意に上昇することが明らかとなっている。そこで今回は、アクチビンと濾胞選択の関係について詳細に解析を行った。その結果、アクチビンを発現する濾胞ではアポトーシスが検出されないこと、卵巣をアクチビン存在下で器官培養するとエストラジオールの産生、分泌が誘導され、また、その受容体の発現も有意に上昇することが明らかとなった。これらの結果は、卵巣内で増加するアクチビンによりエストラジオールの産生、分泌が誘導され、そのエストラジオールによりアポトーシスが抑制されるされるというモデルを強く支持する結果である。
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 21K06241
  • Mechanism of follicle selection in mammalian ovary- Is the selection induced by inhibin?
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Apr. 2018 - Mar. 2021
    OGIWARA Katsueki
    The present study aims to elucidate a molecular mechanism of mouse follicle selection. Most primordial follicles that have started growing die by apoptosis, and only the survived follicles are ovulated. Many investigators have studied about it, but the detail is still unclear. The present study was carried out using a hormone substance that is suggested to suppress follicle selection (apoptosis). The results suggest that production and secretion of estradiol 17b (E2) are regulated by Activin-A induced by FSH and that E2 is involved in apoptosis. Based on the results, we propose a model that apoptosis is controlled by E2.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 18K06306
  • A study on medaka ovulation with an emphasis on the relation with oocyte maturational event
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Apr. 2016 - Mar. 2019
    Takahashi Takayuki
    The purpose of this project was to examine whether ovualtion and oocyte maturation, which are both triggered by the ovulatory surge of LH in vertebrates, would be closely linked, and if any, what would be the mechanism by which the two processes occur in harmony? To this end, we used an in vitro ovulation system established for medaka ovarian follicles. Assuming that gap junctional communication between follicle cells and the oocyte and/or between two neighboring follicle cells might play an important role in ovulating follicles, we examine the effect of gap junction blockers on ovulation and oocyte maturation. In vitro follicle ovulation, but not oocyte maturation, was strongly inhibited by the blockers. The inhibition of follicle ovulation by gap junction blockers was demonstrated to be accompanied by the inhibition of MT2-MMP expression. In addition, we suggest that several connexin species may be involved in the gap junctional communication for successful ovulation.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 16H04810
  • Studies on the molecular mechanism for the rapid regenaration and degradation of follicle layers of the medaka follicles after ovulation.
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Apr. 2015 - Mar. 2018
    OGIWARA Katsueki
    Ovulation is the process that fertilizable oocytes are released into the ovarian sac.The precess is involved in a breakdown of the follicular wall,which are composed of folicular tissues and ovarian surface tissues.In medaka, which ovulates every day, the tissue repair of the follicle wall starts just after ovulation, and follicular tissues that had released an oocyte are degraded rapidly in the ovary. The aim of the present study is to elucidate the molecular mechanism of the process.Cadherin protein was suggested to be involved in the tissue repair of the follicle wall.Gelatinase B and plasmin, both of which were expressed in follicular tissues that had released an oocyte, were implied to be implicated in the rapid degradation of the follicle tissues in the ovary. We will continue to study to elucidate the molecular mechanism of the rapid tissue repair, based on the results abtained from the present study.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 15K07120
  • Ovulation in medaka: Endocrine regulation and the relation with the event of oocyte maturation
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    May 2012 - Mar. 2016
    Takahashi Takayuki; OGIWARA KATSUEKI
    Using in vitro ovulation system established for medaka ovarian follicles, we investigated the mechanism by which ovulation-related genes/proteins, membrane type-2 matrix metalloproteinase (MT2-MMP) and prostaglandin E2 receptor subtype (EP4b) were induced at ovulation. Expression of both genes/proteins was under the control of LH. Our data indicated that LH induced the expression of a transcription factor nuclear progestin receptor (nPR) in the granulosa cells and that nPR, together with other transcription factors, played roles in the subsequent expression of MT2-MMP and EP4b. We next examined if a communication between granulosa cells and the oocyte in the follicles may be important for successful ovulation. Preovulatory follicles were treated with carbenoxolone, a gap-junction inhibitor, using in vitro ovulation system. We found strong inhibition of MT2-MMP expression by the treatment, indicating that ovulation would be influence by oocyte maturation event occurring in the oocyte.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 24247010
  • Elucidation of the endocrine regulatory mechanism common in vertebrate ovulation.
    Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (A)
    Apr. 2011 - Mar. 2014
    OGIWARA Katsueki
    The aim of the present study is to elucidate the endocrine regulatory mechanism of ovulation in the medaka. The study disclosed a mechanism for inducing nuclear progestin receptor (nPR), which was the essential transcription factor for induction of ovulation-associated genes. It was revealed that nPR was involved in the induction of MT2-MMP and PAI-1, both which played an important role on ovulation. An expression pattern of the synthesizing enzymes for a maturation inducing hormone (17a, 20b-DHP), a ligand of nPR, was elucidated. Based on the results, we propose the novel model of the endocrine regulatory mechanism for inducing the ovulation-related enzymes responsible for degradation of follicle layer during ovulation.
    Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (A), Hokkaido University, 23687009
  • Studies on the role of prostagalandins in the induction of ovulation in vertebrates
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    2009 - 2011
    TAKAHASHI Takayuki; OGIWARA Katsueki
    In in vitro ovulation system using medaka ovarian preovulatory follicles, we confirmed that prostaglandin E2 (PGE2) played a role in the fish ovulation. Activity levels of cyclooxygenase-2, the enzyme responsible for PGE2 synthesis, and intrafollicular levels of PGE2 were both relatively constant, while the transcript levels of EP4b, a PGE2 receptor subtype, were drastically induced at ovulation, indicating the importance of induction of the receptor for PGE2's effect on medaka ovulation. Transcription of EP4b gene was demonstrated to be regulated by luteininzing hormone and nuclear progesterone receptor.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 21370024
  • Identification of mammalian ovulation enzymes using in vitro ovulation system and elucidation of ovulation mechanism.
    Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
    2009 - 2010
    OGIWARA Katsueki
    The aim of the present study were to identify the mouse ovulation enzymes responsible for degradation of the follicle wall during ovulation, and to elucidate the molecular mechanism of degradation of the follicle wall during ovulation. It was also attempted to improve the culture condition by optimizing the buffer system and by changing the supplements added. As results, it was found that two MMPs were changed their expression between before and after ovulation. However, it was suggested that they were not involved in ovulation. Active form of MT2-MMP was found to be increased before ovulation, implying that it was involved in ovulation.
    Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Hokkaido University, 21770067
  • 排卵酵素遺伝子のトランスジェニックRNAiメダカ作製への挑戦
    Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
    2009 - 2010
    高橋 孝行; 荻原 克益
    昨年度の解析から、哺乳類型siRNAがメダカにおいては効率の良いノックダウン効果を示さないことが示唆されたため、始めにこの点についてより詳細な解析を行った。メダカ培養細胞を用いて強制発現させたMT2-MMPおよびuPAのノックダウン効率を調査したところ、化学合成したsiRNA、miRNA発現ベクターを用いて発現させたsiRNAともにほとんど効果がないことが判明した。これらの結果から,メダカ細胞においては、哺乳類型siRNAが作用し難いことが考えられる。この理由として、メダカで作用するsiRNAの長さが哺乳類型とは異なることが考えられる。そこで、この点に焦点を絞って解析を行った。siRNA産生において重要な因子であるDicerのリコンビンナントタンパク質を用いてdsRNAの切断実験を試みたところ、20-30塩基付近に切断産物が得られたため、現在この産物の配列情報を解析中である。また、RISCの主要構成因子であるArgonaute-2のメダカ特異的抗体を作製、この抗体を用いて免疫沈降を行い、共沈してきたsmall RNA分子の長さを解析中である。これらの解析結果から、メダカで作用するsiRNAの長さを明らかにし、効率良くノックダウン可能な発現ベクター構築へと移行していく予定である。さらに、Droshaに関しても全長配列のクローニングが終了し、リコンビナントタンパク質および抗体作製へと移行した。今後は、こちらに関しても、リコンビナントタンパク質の準備ができ次第、詳細な解析を行う予定である。
    マウスではトランスジェニックRNAi技術はすでに確立され、標的とする遺伝子/タンパク質の個体レベルでの解析研究が著しい進展を見せている。本研究は、マウス以外の脊椎動物でも同様の技術を確立することを目指し、メダカを実験材料に2年間の研究計画を提案した。本研究により、マウスとは異なるメカニズムがあることが明らかになったので、これを基盤としてトランスジェニックRNAiメダカの確立に向けてさらに研究を進める予定である。
    Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Hokkaido University, 21657019
  • Establishment of culture system for identification of mammalian ovulatory enzymes and their identification using the system
    Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
    2007 - 2008
    OGIWARA Katsueki
    本研究は、哺乳類(マウス)排卵酵素の探索ならびに同定を目指して実施された。その結果、排卵酵素探索のツールとして重要な生体外排卵培養系について、より排卵数の多い培養条件を突きとめることに成功した。また、メタロプロテアーゼが排卵酵素であることを示唆する結果を得た。さらに、排卵前後で発現変動するいくつかのメタロプロテアーゼを発見した。これらの結果は、哺乳類排卵酵素同定の足がかりとして重要な成果であると考えられる。
    Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Hokkaido University, 19770047
■ Industrial Property Rights
  • 魚類由来のエンテロペプチダーゼ
    Patent right, 高橋 孝行; 荻原 克益, 国立大学法人北海道大学
    特願2004-066632, 10 Mar. 2004
    特開2005-253325, 22 Sep. 2005
    特許第4474543号
    19 Mar. 2010
    200903031561438453