A novel function for the sperm adhesion protein IZUMO1 in cell–cell fusion
HIGASHIYAMA Tetsuya
Nov. 19, 2023
Mammalian sperm–egg adhesion depends on the trans-interaction between the sperm-specific type I glycoprotein IZUMO1 and its oocyte-specific GPI-anchored receptor JUNO. However, the mechanisms and proteins (fusogens) that mediate the following step of gamete fusion remain unknown. Using live imaging and content mixing assays in a heterologous system and structure-guided mutagenesis, we unveil an unexpected function for IZUMO1 in cell-to-cell fusion. We show that IZUMO1 alone is sufficient to induce fusion, and that this ability is retained in a mutant unable to bind JUNO. On the other hand, a triple mutation in exposed aromatic residues prevents this fusogenic activity without impairing JUNO interaction. Our findings suggest a second function for IZUMO1 as a unilateral mouse gamete fusogen.
Brukman Nicolas G., Nakajima Kohdai P., Valansi Clari, Flyak Kateryna, Li Xiaohui, Higashiyama Tetsuya, Podbilewicz Benjamin
Journal of Cell Biology (222) e202207147
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