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Ikawa Lab／Bioinformatics Center  Department of Experimental Genome Research

In the past, animals harboring natural mutations have been used to elucidate the mechanisms underlying various diseases.
In the “post-genome project era,” genetically modified animals play a key role in basic molecular biological investigations and act as models of human disease. Our laboratory studies the mechanisms underlying mammalian reproductive systems through genetic manipulation of animal models.

Alalysis of molecular mechanisms involved in mammalian reproduction

Our laboratory focuses to mechanistically study the mammalian reproduction system in vivo using gene-manipulated animals. We were the first laboratory in the world to produce genetically modified mice that express a green fluorescent protein (GFP) throughout the body (Fig. 1).

These green fluorescent mice are useful for many types of research projects. Indeed, we used these animals to label sperm with a fluorescent protein and visualized the fertilization process (Exp Anim. 2010; JCS. 2010, 2012; PNAS. 2012, 2013) (Fig. 2)

 

We introduced the cutting edge CRISPR/Cas9 system and have been improving the technology (SciRep. 2013, 2016; Science 2018). By utilizing the system, we have recently elucidated the lumicrine system; testis derived NELL2 go through the male reproductive tract's luminal space and triggers differentiation of epididymal epithelial cells through ROS1 receptor kinase. Then, activated epididymal cells secrets OVCH2 protease that modulate sperm fertilizing ability by trimming sperm membrane ADAM3 protein (Publication 3). We also found that sperm calcineurin (PPP3CC/PPP3R2) is essential for sperm motility and male fertility (publication 6). Inhibiting sperm calcineurin may lead to the development of a reversible male contraceptive.

More recently, besides IZUMO1 (Nature 2005), we found novel sperm proteins essential for the sperm-oocyte fusion process (Publications 4 and 5). Our laboratory will continue elucidating the mammalian fertilization mechanism.

Development of new technologies for producing genetically modified animals

Another tool improved by work in our laboratory is lentiviral (LV) vector-mediated genetic manipulation in vivo. We developed the technique of placenta-specific gene manipulation by transducing blastocyst stage embryos with LV vectors (Nat Biotechnol. 2007; PNAS. 2011). Using this technique, we are trying to elucidate the mechanism underlying implantation and placentation.

 

Our laboratory and the Animal Resource Center for Infectious Diseases support services such as the generation of genetically modified animals, in vitro fertilization, and cryopreservation of mouse strains.

 

For more information about our research and services, please visit our homepage (https://egr.biken.osaka-u.ac.jp/).

 

 

  • Fig. 1. GFP-expressing mice. Our “Green mice” have been used for more than hundreds of researchers and are good models for studying human disease (FEBS Lett 1997;407:313-319). Fig. 2. RBGS sperm. Transgenic spermatozoa carrying GFP and dDsRed2 in their acrosome and mitochondria. These gametes are useful to visualize the fertilization process (Exp Anim 2010;59:105-107).

  • Fig. 3. Calcineurin deficient sperm. Serm calcineurin is required for sperm motility for successful fertilization (Science 2015;350:442-445).

  • Fig. 4. Lentirival vector-mediated transgenesis in mice. Lentiviral vectors are not able to transduce eggs with zona pellucida (ZP) (left). Without ZP, transductions of fertilized egg and blastocyst result in the whole transgenic (middle) and placenta-specific transgenic (right), respectively (Nat Biotechnol 2007;25:233-237).

Staff

  • Prof.: Masahito Ikawa
  • Assoc. Prof.: Haruhiko Miyata
  • SA Assoc. Prof.: Yonggang Lu (concur.)
  • SA Assoc. Prof.: Hideto Mori (concur.)
  • Asst. Prof.: Keisuke Shimada(concur.)
  • Asst. Prof.: Chihiro Emori
  • Asst. Prof.: Maki Kamoshita(concur.)
  • SA Asst. Prof. : Takehiro Hiraoka
  • SA Asst. Prof. : Daisuke Mashiko(concur.)
  • SA Asst. Prof. : Yuki Hatanaka(concur.)
  • Postdoc. : Rie Iida
  • Postdoc. : Shingo Tonai

Website

Publications

  • 1) ARMC12 regulates spatiotemporal mitochondrial dynamics during spermiogenesis and is required for male fertility. Shimada K., PNAS. 2021 Feb 9;118(6):e2018355118.
    2）Bi-allelic DNAH8 Variants Lead to Multiple Morphological Abnormalities of the Sperm Flagella and Primary Male Infertility. Liu C., et al. Am J Hum Genet. 2020 Aug 6;107(2):330-341.
    3) NELL2-mediated lumicrine signaling through OVCH2 is required for male fertility. Kiyozumi D., et al. Science. 2020 Jun 5;368(6495):1132-1135.
    4) Sperm proteins SOF1, TMEM95, and SPACA6 are required for sperm-oocyte fusion in mice. Noda T., et al. PNAS. 2020 May 26;117(21):11493-11502.
    5) Spermatozoa lacking Fertilization Influencing Membrane Protein (FIMP) fail to fuse with oocytes in mice. Fujihara Y., et al. PNAS. 2020 Apr 28;117(17):9393-9400.
    6) Sperm calcineurin inhibition prevents mouse fertility with implications for male contraceptive. Miyata H., Science. 2015 Oct 23;350(6259):442-5.

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