Eum Jin Hee, Park Miseon, Yoon Jung Ah, Yoon Sook Young
Fertility Center of CHA Gangnam Medical Center, Seoul 06125, Korea.
Dev Reprod. 2020 Dec;24(4):297-306. doi: 10.12717/DR.2020.24.4.297. Epub 2020 Dec 31.
Repetitive changes in the intracellular calcium concentration ([Ca]i) triggers egg activation, including cortical granule exocytosis, resumption of second meiosis, block to polyspermy, and initiating embryonic development. [Ca]i oscillations that continue for several hours, are required for the early events of egg activation and possibly connected to further development to the blastocyst stage. The sources of Ca ion elevation during [Ca]i oscillations are Ca release from endoplasmic reticulum through inositol 1,4,5 tri-phosphate receptor and Ca ion influx through Ca channel on the plasma membrane. Ca channels have been characterized into voltage-dependent Ca channels (VDCCs), ligand-gated Ca channel, and leak-channel. VDCCs expressed on muscle cell or neuron is specified into L, T, N, P, Q, and R type VDCs by their activation threshold or their sensitivity to peptide toxins isolated from cone snails and spiders. The present study was aimed to investigate the localization pattern of N and P/Q type voltage-dependent calcium channels in mouse eggs and the role in fertilization. [Ca]i oscillation was observed in a Ca contained medium with sperm factor or adenophostin A injection but disappeared in Ca free medium. Ca influx was decreased by Lat A. N-VDCC specific inhibitor, ω-Conotoxin CVIIA induced abnormal [Ca]i oscillation profiles in SrCl treatment. N or P/Q type VDC were distributed on the plasma membrane in cortical cluster form, not in the cytoplasm. Ca influx is essential for [Ca]i oscillation during mammalian fertilization. This Ca influx might be controlled through the N or P/Q type VDCCs. Abnormal VDCCs expression of eggs could be tested in fertilization failure or low fertilization eggs in subfertility women.
细胞内钙浓度（[Ca]i）的反复变化触发卵子激活，包括皮质颗粒胞吐、第二次减数分裂恢复、多精受精阻断以及启动胚胎发育。持续数小时的[Ca]i振荡是卵子激活早期事件所必需的，并且可能与进一步发育到囊胚阶段有关。[Ca]i振荡期间钙离子升高的来源是通过肌醇1,4,5-三磷酸受体从内质网释放的钙以及通过质膜上的钙通道流入的钙离子。钙通道已被分为电压依赖性钙通道（VDCCs）、配体门控钙通道和渗漏通道。在肌肉细胞或神经元上表达的VDCCs根据其激活阈值或对从锥螺和蜘蛛中分离出的肽毒素的敏感性分为L、T、N、P、Q和R型VDCCs。本研究旨在研究N型和P/Q型电压依赖性钙通道在小鼠卵子中的定位模式及其在受精中的作用。在含有精子因子或注射了腺嘌呤毒素A的含钙培养基中观察到[Ca]i振荡，但在无钙培养基中消失。Lat A降低了钙内流。N-VDCC特异性抑制剂ω-芋螺毒素CVIIA在SrCl处理中诱导了异常的[Ca]i振荡模式。N型或P/Q型VDC以皮质簇的形式分布在质膜上，而不是在细胞质中。钙内流对于哺乳动物受精期间的[Ca]i振荡至关重要。这种钙内流可能通过N型或P/Q型VDCCs来控制。卵子中异常的VDCCs表达可以在不育女性的受精失败或低受精率卵子中进行检测。
