Elucidation of the transcriptional regulation of ROS in Spermatogonial Stem cells

• Project/Area Number: 17K08136
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Integrative animal science
• Research Institution: Kyoto University
• Principal Investigator: Morimoto Hiroko 京都大学, 医学研究科, 助教 (90540097)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000); Fiscal Year 2019: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000); Fiscal Year 2018: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2017: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
• Keywords: 精子幹細胞 / 活性酸素

Outline of Final Research Achievements

We found that the MAPK14/MAPK7/BCL6B pathway creates a positive feedback loop to drive spermatogonial stem cell (SSC) self-renewal via ROS amplification. The activation of MAPK14 induced MAPK7 phosphorylation in cultured SSCs, and targeted deletion of Mapk14 or Mapk7 resulted in significant SSC deficiency after spermatogonial transplantation. The activation of this signaling pathway not only induced Nox1 but also increased ROS levels. Chemical screening of MAPK7 targets revealed many ROS-dependent spermatogonial transcription factors, of which BCL6B was found to initiate ROS production by increasing Nox1 expression via ETV5-induced nuclear translocation. Because hydrogen peroxide or Nox1 transfection also induced BCL6B nuclear translocation, our results suggest that BCL6B initiates and amplifies ROS signals to activate ROS-dependent spermatogonial transcription factors by forming a positive feedback loop.

Academic Significance and Societal Importance of the Research Achievements

生殖細胞研究ではROSは生殖細胞に悪影響を与えるものである考えられていた。ROSの過剰をもたらすSod2やNrf2のノックアウトマウスにおいては精子形成が不完全となり不妊となる。男性不妊治療の臨床現場でもROSの抑制が試みられている。ROSが精子幹細胞の自己複製に必要であるという結果は大きな反響があった。しかしこれらの異なるノックアウトマウスが何故異なった表現型を示すのかについては未だ回答が得られておらず、本研究でアプローチする問題は次の大事なステップであると申請者は考えている。このようにROSが精子幹細胞の自己複製に及ぼす影響を解析することは臨床での不妊治療にも影響を及ぼす重要課題である。

Research Products

• [Journal Article] Expression and functional analyses of EPHA2 in mouse spermatogonial stem cells. (2020)
  • Author(s): Morimoto, H., Kanatsu-Shinohara, M., Orwig, K. E. and Shinohara, T.
  • Journal Title: Biol. Reprod. Volume: 102 Issue: 1 Pages: 220-232
  • DOI: 10.1093/biolre/ioz156
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] CD2 is a surface marker for mouse and rat spermatogonial stem cells. (2020)
  • Author(s): Kanatsu-Shinohara M, Chen G, Morimoto H, Shinohara T.
  • Journal Title: J Reprod Dev. Volume: Mar 26. Issue: 4 Pages: 1-32
  • DOI: 10.1262/jrd.2020-019
  • NAID: 130007888738
  • Peer Reviewed / Open Access
• [Journal Article] ROS amplification drives mouse spermatogonial stem cell self-renewal. (2019)
  • Author(s): Morimoto H, Kanatsu-Shinohara M, Ogonuki N, Kamimura S, Ogura A, Yabe-Nishimura C, Mori Y, Morimoto T, Watanabe S, Otsu K, Yamamoto T, *Shinohara T.
  • Journal Title: Life Sci Alliance Volume: 2 Issue: 2 Pages: 2-2
  • DOI: 10.26508/lsa.201900374
  • Peer Reviewed / Open Access
• [Journal Article] Reversible inhibition of the blood-testis barrier protein improves stem cell homing in mouse testes (2018)
  • Author(s): Kanatsu-Shinohara M, Morimoto H, Watanabe S, Shinohara T.
  • Journal Title: Journal of Reproduction and Development Volume: 64 Issue: 6 Pages: 511-522
  • DOI: 10.1262/jrd.2018-093
  • NAID: 130007530501
  • ISSN: 0916-8818, 1348-4400
  • Peer Reviewed
• [Journal Article] Transfer of a mouse artificial chromosome into spermatogonial stem cells genetates transchromosomic mice, (2017)
  • Author(s): Shinohara T, Kazuki K, Ogonuki N, Morimoto H, Matoba S, Hiramatsu K, Honma K, Suzuki T, Hara T, Ogura A, Oshimura M, Kanatsu-Shinohara M, Kazuki Y.
  • Journal Title: Stem Cell Reports. Volume: 9(4) Issue: 4 Pages: 1180-1191
  • DOI: 10.1016/j.stemcr.2017.08.012
  • Peer Reviewed / Open Access