WD repeat-containing protein 41 (WDR41) is involved in fertilization and interacts with IZUMO1 and JUNO.

During mammalian fertilization, sperm-oocyte recognition, binding, and subsequent plasma membrane fusion are facilitated by specific protein-protein interactions. Among these interactions, the IZUMO1-JUNO receptor pair is considered important for the adhesion and fusion of sperm and oocyte. However, the IZUMO1-JUNO interaction alone is insufficient to mediate membrane fusion, suggesting that the coordinated interactions of other proteins are required. In this study, we aimed to identify novel molecular players that interact with IZUMO1 and JUNO and investigate their functional roles in fertilization. We identified WD repeat-containing protein 41 (WDR41) as a potential interactor, which is present in the sperm head and metaphase II oocytes and interacts with IZUMO1 and JUNO. Functional inhibition of WDR41 using a specific anti-WDR41 antibody significantly reduced in vitro fertilization rates, regardless of whether the antibody was used to capacitate sperm or zona pellucida-free oocytes. Furthermore, the fertilization rate reduced from 84.1 ± 3.0% (control) to 64.0 ± 1.5% when the antibody was applied to capacitated sperm (p < 0.01), and from 83.0 ± 2.9% (control) to 45.3 ± 1.3% when applied to zona pellucida-free oocytes (p < 0.01). Furthermore, high-resolution co-localization analyses showed that WDR41 co-localizes with IZUMO1 on the sperm head and with JUNO on the oolemma. Altogether, our results suggest that WDR41, a previously unrecognized regulator of fertilization, functions as an accessory protein alongside the IZUMO1-JUNO axis and contributes to the molecular network involved in fertilization.