Reproductive and Developmental Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709.
Department of Biology and Chemistry, Faculty of Basic Sciences, Universidad Católica del Maule, 3480112 Talca, Chile.
Proc Natl Acad Sci U S A. 2018 Oct 30;115(44):E10370-E10378. doi: 10.1073/pnas.1810422115. Epub 2018 Oct 15.
The success of mammalian development following fertilization depends on a series of transient increases in egg cytoplasmic Ca, referred to as Ca oscillations. Maintenance of these oscillations requires Ca influx across the plasma membrane, which is mediated in part by T-type, Ca3.2 channels. Here we show using genetic mouse models that TRPM7 channels are required to support this Ca influx. Eggs lacking both TRPM7 and Ca3.2 stop oscillating prematurely, indicating that together they are responsible for the majority of Ca influx immediately following fertilization. Fertilized eggs lacking both channels also frequently display delayed resumption of Ca oscillations, which appears to require sperm-egg fusion. TRPM7 and Ca3.2 channels almost completely account for Ca influx observed following store depletion, a process previously attributed to canonical store-operated Ca entry mediated by STIM/ORAI interactions. TRPM7 serves as a membrane sensor of extracellular Mg and Ca concentrations and mediates the effects of these ions on Ca oscillation frequency. When bred to wild-type males, female mice carrying eggs lacking TRPM7 and Ca3.2 are subfertile, and their offspring have increased variance in postnatal weight. These in vivo findings confirm previous observations linking in vitro experimental alterations in Ca oscillatory patterns with developmental potential and offspring growth. The identification of TRPM7 and Ca3.2 as key mediators of Ca influx following fertilization provides a mechanistic basis for the rational design of culture media that optimize developmental potential in research animals, domestic animals, and humans.
哺乳动物受精后胚胎的成功发育取决于卵细胞质 Ca 的一系列短暂增加，称为 Ca 振荡。这些振荡的维持需要 Ca 通过质膜内流，部分由 T 型 Ca3.2 通道介导。在这里，我们使用遗传小鼠模型表明，TRPM7 通道对于支持这种 Ca 内流是必需的。缺乏 TRPM7 和 Ca3.2 的卵子会过早停止振荡，表明它们共同负责受精后立即发生的大部分 Ca 内流。缺乏这两种通道的受精卵也经常显示 Ca 振荡恢复延迟，这似乎需要精子-卵子融合。TRPM7 和 Ca3.2 通道几乎完全解释了储存耗尽后观察到的 Ca 内流，这一过程以前归因于由 STIM/ORAI 相互作用介导的经典储存操纵的 Ca 内流。TRPM7 作为细胞外 Mg 和 Ca 浓度的膜传感器，并介导这些离子对 Ca 振荡频率的影响。当与野生型雄性交配时，携带缺乏 TRPM7 和 Ca3.2 的卵子的雌性小鼠繁殖力下降，其后代在出生后体重的变化更大。这些体内发现证实了先前的观察结果，即体外实验改变 Ca 振荡模式与发育潜力和后代生长有关。鉴定 TRPM7 和 Ca3.2 作为受精后 Ca 内流的关键介质，为优化研究动物、家畜和人类的发育潜力的培养基的合理设计提供了机制基础。
