Thapsigargin activates a calcium influx pathway in the unfertilized mouse egg and suppresses repetitive calcium transients in the fertilized egg.
Thapsigargin activates a calcium influx pathway in the unfertilized mouse egg and suppresses repetitive calcium transients in the fertilized egg.
复制标题
DOI：
10.1016/s0021-9258(19)37088-7
复制
发表时间：
1992-09
期刊：
影响因子：
--
通讯作者：
D. Kline;J. T. Kline
中科院分区：
文献类型：
--
作者：
D. Kline;J. T. Kline
在受精时，精子通过诱导细胞内Ca 2+浓度（[Ca 2 +]i）的大量瞬时增加来启动小鼠卵子的发育，随后是[Ca 2 +]i的重复瞬时增加。为了确定重复的Ca 2+瞬变是如何产生的，毒胡萝卜素，内质网Ca-ATP酶的抑制剂，被用来消耗细胞内的Ca 2+储存在鸡蛋。在未受精卵中，毒胡萝卜素（1-50 μ M）引起[Ca 2 +]i的缓慢上升和下降的瞬时增加，有或没有细胞外Ca 2+。钙内流途径被毒胡萝卜素激活，因为在无Ca 2+、Mg（2+）的培养基中，毒胡萝卜素处理后，当向卵中加入Ca 2+时，[Ca 2 +]i立即增加。这表明小鼠卵细胞中的Ca 2+进入可能与细胞内储存的排空有关。受精时的第一个Ca 2+瞬变的幅度减少了多达84%，在用毒胡萝卜素预处理的鸡蛋。减少细胞外Ca 2+，通过添加一个Ca 2+螯合剂，抑制受精后的重复Ca 2+瞬变。Ca 2+瞬变也需要填补细胞内的存储，他们被抑制时，毒胡萝卜素受精前或受精后加入。这些结果支持的假设，即第一个精子诱导的Ca 2+瞬态在受精耗尽细胞内Ca 2+存储，触发质膜Ca 2+渗透性的增加，和增强的Ca 2+内流导致重复的Ca 2+瞬态由于周期性的填充和排空的细胞内Ca 2+存储。
At fertilization, the sperm initiates development of the mouse egg by inducing a large transient increase in the intracellular Ca2+ concentration ([Ca2+]i), which is followed by repetitive transient increases in [Ca2+]i. To determine how the repetitive Ca2+ transients are produced, thapsigargin, an inhibitor of the endoplasmic reticulum Ca-ATPase, was used to deplete intracellular Ca2+ stores within the egg. In the unfertilized egg, thapsigargin (1-50 microM) caused a slowly rising and falling transient increase in [Ca2+]i with or without extracellular Ca2+. An influx pathway for Ca2+ is activated by thapsigargin, since an immediate increase in [Ca2+]i occurred when Ca2+ was added to eggs after thapsigargin treatment in a Ca2+, Mg(2+)-free medium. This suggests that Ca2+ entry in the mouse egg may be coupled to the emptying of an intracellular store. The magnitude of the first Ca2+ transient at fertilization was reduced by as much as 84% in eggs pretreated with thapsigargin. Reduction of extracellular Ca2+, by addition of a Ca2+ chelator, suppressed the repetitive Ca2+ transients following fertilization. The Ca2+ transients also require filling of an intracellular store; they were suppressed when thapsigargin was added before or after fertilization. These results support the hypothesis that the first sperm-induced Ca2+ transient at fertilization depletes an intracellular Ca2+ store, triggering an increase in plasma membrane Ca2+ permeability, and that the enhanced Ca2+ influx causes repetitive Ca2+ transients due to the periodic filling and emptying of an intracellular Ca2+ store.