Repetitive oscillations in cytoplasmic Ca2+ due to periodic Ca2+ release from the endoplasmic reticulum (ER) drive mammalian embryo development following fertilization. Influx of extracellular Ca2+ to support the refilling of ER stores is required for sustained Ca2+ oscillations, but the mechanisms underlying this Ca2+ influx are controversial. Although store-operated Ca2+ entry (SOCE) is an appealing candidate mechanism, several groups have arrived at contradictory conclusions regarding the importance of SOCE in oocytes and eggs. To definitively address this question, Ca2+ influx was assessed in oocytes and eggs lacking the major components of SOCE, the ER Ca2+ sensor STIM proteins, and the plasma membrane Ca2+ channel ORAI1. We generated oocyte-specific conditional knockout (cKO) mice for Stim1 and Stim2, and also generated Stim1/2 double cKO mice. Females lacking one or both STIM proteins were fertile and their ovulated eggs displayed normal patterns of Ca2+ oscillations following fertilization. In addition, no impairment was observed in ER Ca2+ stores or Ca2+ influx following store depletion. Similar studies were performed on eggs from mice globally lacking ORAI1; no abnormalities were observed. Furthermore, spontaneous Ca2+ influx was normal in oocytes from Stim1/2 cKO and ORAI1-null mice. Finally, we tested if TRPM7-like channels could support spontaneous Ca2+ influx, and found that it was largely prevented by NS8593, a TRPM7-specific inhibitor. Fertilization-induced Ca2+ oscillations were also impaired by NS8593. Combined, these data robustly show that SOCE is not required to support appropriate Ca2+ signaling in mouse oocytes and eggs, and that TRPM7-like channels may contribute to Ca2+ influx that was previously attributed to SOCE.

中文翻译：

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受精诱导的小鼠卵中Ca2 +信号传导不需要商店操作的Ca2 +进入。

由于周期性地从内质网（ER）释放Ca2 +，导致细胞质Ca2 +的重复振荡驱动受精后的哺乳动物胚胎发育。持续的Ca2 +振荡需要大量的细胞外Ca2 +流入以支持ER储存的补充，但是引起Ca2 +流入的机制尚存争议。尽管通过存储操作的Ca2 +进入（SOCE）是一个有吸引力的候选机制，但是关于SOCE在卵母细胞和卵子中的重要性，一些研究小组得出了相互矛盾的结论。为了明确解决这个问题，在缺乏SOCE，ER Ca2 +传感器STIM蛋白和质膜Ca2 +通道ORAI1的主要成分的卵母细胞和卵中评估了Ca2 +流入。我们为Stim1和Stim2生成了卵母细胞特异性条件基因敲除（cKO）小鼠，并且还产生了Stim1 / 2 double cKO小鼠。缺少一种或两种STIM蛋白的雌性可育，其排卵卵在受精后表现出正常的Ca2 +振荡模式。此外，在ER Ca2 +储库中未观察到损害或在库耗尽后Ca2 +涌入。对全球缺乏ORAI1的小鼠的卵进行了类似的研究。没有观察到异常。此外，来自Stim1 / 2 cKO和ORAI1-null小鼠的卵母细胞中自发的Ca2 +内流正常。最后，我们测试了TRPM7样通道是否可以支持自发的Ca2 +流入，并发现它很大程度上被TRPM7特异性抑制剂NS8593阻止了。受精诱导的Ca2 +振荡也被NS8593削弱。综合起来，这些数据有力地表明，不需要SOCE支持小鼠卵母细胞和卵中适当的Ca2 +信号传导，