Wang Huizhen, Kinsey William H
Department of Anatomy & Cell Biology, University of Kansas School of Medicine, Kansa City, KS, United States.
Front Cell Dev Biol. 2022 May 13;10:886664. doi: 10.3389/fcell.2022.886664. eCollection 2022.
Sperm interaction with the oocyte plasma membrane triggers a localized response in the mouse oocyte that leads to remodeling of oocyte surface as well as the underlying cortical actin layer. The recent demonstration that PTK2B is recruited and activated at the sperm binding site raised the possibility that multiple signaling events may be activated during this stage of fertilization. The present study demonstrated that β-catenin and Rho A were recruited to the cortex underlying bound/fused sperm. To determine whether sperm-oocyte contact was sufficient to initiate β-catenin recruitment, -null, and PTK2b-null oocytes were tested for the ability to recruit β-catenin to sperm binding sites. Both and ablation reduced β-catenin recruitment raising the possibility that PTK2B may act downstream of CD9 in the response to sperm binding/fusion. Further immunofluorescence study revealed that β-catenin co-localized with f-actin in the interstitial regions between actin layer fenestrae. Rho A, in contrast, was arranged underneath the actin layer in both the fenestra and the interstitial regions suggesting that they may play different roles in the oocyte.
精子与卵母细胞质膜的相互作用会在小鼠卵母细胞中引发局部反应，这会导致卵母细胞表面以及其下方的皮质肌动蛋白层发生重塑。最近有研究表明，PTK2B在精子结合位点被募集并激活，这增加了在受精这个阶段可能会激活多个信号事件的可能性。本研究表明，β-连环蛋白和Rho A被募集到与精子结合/融合部位下方的皮质。为了确定精子与卵母细胞的接触是否足以启动β-连环蛋白的募集，对缺失CD9和PTK2b的卵母细胞进行了检测，以评估其将β-连环蛋白募集到精子结合位点的能力。CD9和PTK2b的缺失均降低了β-连环蛋白的募集，这增加了PTK2B可能在对精子结合/融合的反应中作用于CD9下游的可能性。进一步的免疫荧光研究表明，β-连环蛋白在肌动蛋白层窗孔之间的间隙区域与f-肌动蛋白共定位。相比之下，Rho A在窗孔和间隙区域的肌动蛋白层下方排列，这表明它们可能在卵母细胞中发挥不同的作用。
