Department of Cell Science, Institute of Biomedical Sciences, School of Medicine, Fukushima Medical University, 1 Hikarigaoka, Fukushima City, Fukushima 960-1295, Japan
Department of Cell Science, Institute of Biomedical Sciences, School of Medicine, Fukushima Medical University, 1 Hikarigaoka, Fukushima City, Fukushima 960-1295, Japan.
Development. 2020 Aug 14;147(15):dev189985. doi: 10.1242/dev.189985.
Gamete fusion is an indispensable process for bearing offspring. In mammals, sperm IZUMO1-oocyte JUNO recognition essentially carries out the primary step of this process. In oocytes, CD9 is also known to play a crucial role in gamete fusion. In particular, microvilli biogenesis through CD9 involvement appears to be a key event for successful gamete fusion, because CD9-disrupted oocytes produce short and sparse microvillous structures, resulting in almost no fusion ability with spermatozoa. In order to determine how CD9 and JUNO cooperate in gamete fusion, we analyzed the molecular profiles of each molecule in CD9- and JUNO-disrupted oocytes. Consequently, we found that CD9 is crucial for the exclusion of GPI-anchored proteins, such as JUNO and CD55, from the cortical actin cap region, suggesting strict molecular organization of the unique surface of this region. Through distinct surface compartmentalization due to CD9 governing, GPI-anchored proteins are confined to the appropriate fusion site of the oocyte.
配子融合是生育后代所必需的过程。在哺乳动物中，精子 IZUMO1-卵母细胞 JUNO 识别基本上执行了这个过程的第一步。在卵母细胞中，CD9 也被认为在配子融合中起着至关重要的作用。特别是，通过 CD9 参与的微绒毛发生似乎是配子融合成功的关键事件，因为 CD9 破坏的卵母细胞产生短而稀疏的微绒毛结构，导致与精子几乎没有融合能力。为了确定 CD9 和 JUNO 如何在配子融合中合作，我们分析了 CD9 和 JUNO 破坏的卵母细胞中每个分子的分子特征。结果，我们发现 CD9 对于将 GPI-锚定蛋白（如 JUNO 和 CD55）排除在皮质肌动蛋白帽区域至关重要，这表明该区域独特表面的严格分子组织。通过 CD9 控制的独特表面区室化，GPI-锚定蛋白被限制在卵母细胞的适当融合部位。
