Miyazaki S, Shirakawa H, Nakada K, Honda Y
Department of Physiology, Tokyo Women's Medical College, Japan.
Dev Biol. 1993 Jul;158(1):62-78. doi: 10.1006/dbio.1993.1168.
At fertilization mammalian eggs exhibit repetitive rises in the cytoplasmic Ca2+ concentration (Ca2+ oscillations), associated with propagating Ca2+ waves in the initial responses. The Ca2+ oscillation causes cortical granule exocytosis and resumption of second meiosis and affects later embryonic development. Recent studies using a function-blocking monoclonal antibody to the inositol 1,4,5-trisphosphate (InsP3) receptor/Ca2+ release channel demonstrated direct evidence that InsP3-induced Ca2+ release (IICR) from intracellular stores operates at fertilization of the hamster egg and that IICR is essential in the initiation, propagation, and oscillation of the sperm-induced Ca2+ rises. Ca(2+)-induced Ca2+ release (CICR) has also been suggested, but a sensitizing action of Ca2+ on the InsP3 receptor, i.e., Ca(2+)-sensitized IICR, can serve as a regenerative process of Ca2+ release and could be the basis for Ca2+ waves and Ca2+ oscillations. It is now apparent that signal transduction at fertilization is dependent on sperm-stimulated activation of phospholipase C which causes hydrolysis of phosphatidylinositol bisphosphate and production of InsP3, leading to IICR. On the other hand, Ca2+ signaling at fertilization of the sea urchin egg may also involve ryanodine receptor-mediated CICR.
在受精时，哺乳动物卵子的细胞质钙离子浓度会出现重复性升高（钙离子振荡），这与初始反应中传播的钙离子波有关。钙离子振荡会导致皮质颗粒胞吐和第二次减数分裂的恢复，并影响后期胚胎发育。最近使用针对肌醇1,4,5-三磷酸（InsP3）受体/钙离子释放通道的功能阻断单克隆抗体进行的研究，直接证明了细胞内储存库中InsP3诱导的钙离子释放（IICR）在仓鼠卵子受精时起作用，并且IICR在精子诱导的钙离子升高的起始、传播和振荡中至关重要。也有人提出了钙离子诱导的钙离子释放（CICR），但是钙离子对InsP3受体的敏化作用，即钙离子敏化的IICR，可以作为钙离子释放的再生过程，并且可能是钙离子波和钙离子振荡的基础。现在很明显，受精时的信号转导依赖于精子刺激激活磷脂酶C，磷脂酶C会导致磷脂酰肌醇二磷酸水解并产生InsP3，从而导致IICR。另一方面，海胆卵子受精时的钙离子信号传导也可能涉及雷诺丁受体介导的CICR。
