| First Author | Saito T | Year | 2019 |
| Journal | Sci Rep | Volume | 9 |
| Issue | 1 | Pages | 3151 |
| PubMed ID | 30816314 | Mgi Jnum | J:275429 |
| Mgi Id | MGI:6304658 | Doi | 10.1038/s41598-019-40130-7 |
| Citation | Saito T, et al. (2019) Alternative splicing of the Izumo1 gene ensures triggering gamete fusion in mice. Sci Rep 9(1):3151 |
| abstractText | IZUMO1 is a sperm acrosomal membrane protein that is essential for mammalian fertilization through recognition of JUNO on the oocyte surface and accompanying IZUMO1-JUNO complex formation. Here, we report a new Izumo1 gene splicing variant (IZUMO1_v2) with a unique 52-amino-acid-long signal sequence transcribed from Exon 1b. Although the mRNA amount of Izumo1_v2 is 76 times lower than that of the original Izumo1 (IZUMO1_v1) in the testis, the cell-oocyte assay indicates that IZUMO1_v2-expressing COS-7 cells have the ability to attach to the oocyte equivalent of IZUMO1_v1. To clarify the physiological function of IZUMO1_v2, we produced an IZUMO1_v1-specific knockout mouse line with a nine-base deletion adjacent to the initial methionine codon of IZUMO1_v1 by the CRISPR/Cas9 system. The IZUMO1_v1 knockout male mice carry 0.19-fold lower level of IZUMO1 protein in the spermatozoon; however, reduction in fertility was only minimally affected compared to the wild-type mice, suggesting that only a small fraction of IZUMO1 is sufficient for triggering sperm-egg fusion. We propose that the alternative splicing generating IZUMO1_v2 might function as a fail-safe in mouse for when splicing is disturbed. |
