GALECTIN-1 is involved in sperm-egg fusion via interaction with JUNO in rats

Abstract Background: Sexual reproduction is the basic way for higher eukaryotes to reproduce. Fusion of sperm with oocyte is the key process for success of sexual reproduction. Multiple proteins have been identified to be implicated in mammalian sperm-egg fusion, in which only a few, such as IZUMO1 of sperm and JUNO of egg, have been verified by knockout mice to be indispensable to gamete fusion. However, interaction between IZUMO1 and its receptor JUNO mediates sperm-egg recognition and binding, but is unqualified for membrane fusion. Thus, there might be other accessorial proteins interacting with IZUMO1 or/and JUNO for the sperm-egg binding and succeeding membrane fusion. Results: Here, we reported that treatment of rat sperm and egg with anti-Galectin-1 antibody significantly inhibits IVF rate. Galectin-1 was detected on the head and the front half flagellum of rat sperms and in cytoplasm of spermatocytes and the Sertoli cells. It was also found on cell membrane of rat MII eggs as well as in cytoplasm of cumulus cells. Galectin-1 interacts with JUNO and co-localizes with JUNO on the cell membrane and in cytoplasm of rat MII eggs. Conclusions: Our results suggested that Galectin-1 be involved in the process of sperm-egg fusion through interaction with JUNO.