Calcium signaling differentiation during Xenopus oocyte maturation
Calcium signaling differentiation during Xenopus oocyte maturation
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DOI：
10.1016/j.ydbio.2005.10.034
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发表时间：
2005-12-15
影响因子：
2.7
通讯作者：
Machaca, K
中科院分区：
文献类型：
--
作者：
El-Jouni, W;Jang, B;Machaca, K
Ca2+是所有有性生殖物种受精时卵子激活的普遍信号。受精时的Ca2+信号是卵子激活所必需的，并表现出特殊的时空动态。卵子在卵母细胞成熟过程中获得产生受精特异性Ca2+信号的能力。然而，在卵母细胞成熟过程中调节Ca2+信号分化的机制在很大程度上仍然未知。在受精时，爪蟾卵产生持续几分钟的细胞质Ca2+ (Ca2+)上升，这是卵子激活所必需的。在这里，我们发现在卵母细胞成熟过程中钙转运效应被紧密调节。质膜Ca2+ atp酶（PMCA）在成熟过程中完全内化，因此无法将Ca2+挤出细胞。此外，IP3依赖性的Ca2+释放是卵子中持续的钙细胞（2+）上升所必需的，这表明被泵入内质网的钙通过IP3受体漏出，这种明显的徒劳循环允许卵子维持升高的细胞质Ca2+，尽管细胞内储存的可用Ca2+有限。因此，在非洲爪蟾卵母细胞成熟过程中，Ca2+信号以高度协调的方式分化，赋予卵子在受精时产生持续Ca-cyt（2+）瞬态的能力，这决定了卵子激活和启动胚胎发育的能力。(c) 2005爱思唯尔公司版权所有。
Ca2+ is the universal signal for egg activation at fertilization in all sexually reproducing species. The Ca2+ signal at fertilization is necessary for egg activation and exhibits specialized spatial and temporal dynamics. Eggs acquire the ability to produce the fertilization-specifie Ca2+, signal during oocyte maturation. However, the mechanisms regulating Ca2+ signaling differentiation during oocyte maturation remain largely unknown. At fertilization, Xenopus eggs produce a cytoplasmic Ca2+ (Ca2+) rise that lasts for several minutes, and is required for egg activation. Here, we show that during oocyte maturation Ca transport effectors are tightly modulated. The plasma membrane Ca2+ ATPase (PMCA) is completely internalized during maturation, and is therefore unable to extrude Ca2+ out of the cell. Furthermore, IP3-dependent Ca2+ release is required for the sustained Ca-cyt(2+) rise in eggs, showing that Ca that is pumped into the ER leaks back out through IP3 receptors, This, appartent futile cycle allows eggs to maintain elevated cytoplasmic Ca2+ despite the limited available Ca2+ in intracellular stores. Therefore, Ca2+ signaling differentiates in a highly orchestrated fashion during Xenopus oocyte maturation endowing the egg with the capacity to produce a sustained Ca-cyt(2+) transient at fertilization, which defines the egg's competence to activate and initiate embryonic development. (c) 2005 Elsevier Inc. All rights reserved.