| First Author | Fujihara Y | Year | 2020 |
| Journal | Proc Natl Acad Sci U S A | Volume | 117 |
| Issue | 17 | Pages | 9393-9400 |
| PubMed ID | 32295885 | Mgi Jnum | J:287619 |
| Mgi Id | MGI:6415482 | Doi | 10.1073/pnas.1917060117 |
| Citation | Fujihara Y, et al. (2020) Spermatozoa lacking Fertilization Influencing Membrane Protein (FIMP) fail to fuse with oocytes in mice. Proc Natl Acad Sci U S A 117(17):9393-9400 |
| abstractText | Sperm-oocyte fusion is a critical event in mammalian fertilization, categorized by three indispensable proteins. Sperm membrane protein IZUMO1 and its counterpart oocyte membrane protein JUNO make a protein complex allowing sperm to interact with the oocyte, and subsequent sperm-oocyte fusion. Oocyte tetraspanin protein CD9 also contributes to sperm-oocyte fusion. However, the fusion process cannot be explained solely by these three essential factors. In this study, we focused on analyzing a testis-specific gene 4930451I11Rik and generated mutant mice using the CRISPR/Cas9 system. Although IZUMO1 remained in 4930451I11Rik knockout (KO) spermatozoa, the KO spermatozoa were unable to fuse with oocytes and the KO males were severely subfertile. 4930451I11Rik encodes two isoforms: a transmembrane (TM) form and a secreted form. Both CRISPR/Cas9-mediated TM deletion and transgenic (Tg) rescue with the TM form revealed that only the TM form plays a critical role in sperm-oocyte fusion. Thus, we renamed this TM form Fertilization Influencing Membrane Protein (FIMP). The mCherry-tagged FIMP TM form was localized to the sperm equatorial segment where the sperm-oocyte fusion event occurs. Thus, FIMP is a sperm-specific transmembrane protein that is necessary for the sperm-oocyte fusion process. |
