Oscillatory CaMKII activity in mouse egg activation
Oscillatory CaMKII activity in mouse egg activation
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DOI：
10.1016/s0012-1606(03)00133-7
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发表时间：
2003-06-15
影响因子：
2.7
通讯作者：
Ducibella, T
中科院分区：
文献类型：
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作者：
Markoulaki, S;Matson, S;Ducibella, T
受精诱导的细胞内钙（Ca2+）振荡刺激哺乳动物发育的开始，关于这些Ca2+信号被转导到卵子激活事件的生化机制知之甚少。该研究提出了一种假设，即与受精时类似的Ca2+的短暂增加刺激振荡Ca2+/钙调素依赖性激酶II （CaMKII）酶活性，逐渐驱动卵子活化事件。由于受精卵群通常是异步振荡的，因此通过使用离子霉素和操纵细胞外钙，在未受精卵中实验诱导了频率与受精相似的同步振荡Ca2+信号。细胞内Ca2+水平和CaMKII活性的共同分析表明，Ca2+的每一次增加都有快速和短暂的酶反应。酶活性在第一次Ca2+升高时增加了370%，约占最大活性的60%，并在Ca2+达到峰值后的5分钟内降至基础水平。对单个受精卵进行Ca2+监测，CaMKII活性平均增加185%。一次和两次离子霉素诱导的Ca2+瞬态分别导致39%和49%的平均皮质颗粒（CG）损失，而CG胞吐和减数分裂的恢复被CaMKII拮抗剂抑制。这些研究表明，Ca2+水平的变化和CaMKII活性的变化可以在同一个细胞中进行研究，并且CaMKII活性对体内实验诱导的Ca2+振荡非常敏感。这些数据支持CaMKII活性在正常受精后振荡一段时间的假设，并暂时调节卵子激活的许多事件。(C) 2003 Elsevier Science（美国）版权所有。
Fertilization-induced intracellular calcium (Ca2+) oscillations stimulate the onset of mammalian development, and little is known about the biochemical mechanism by which these Ca2+ Signals are transduced into the events of egg activation. This study addresses the hypothesis that transient increases in Ca2+ Similar to those at fertilization stimulate oscillatory Ca2+/calmodulin-dependent kinase II (CaMKII) enzyme activity, incrementally driving the events of egg activation. Since groups of fertilized eggs normally oscillate asynchronously, synchronous oscillatory Ca2+ signaling with a frequency similar to fertilization was experimentally induced in unfertilized mouse eggs by using ionomycin and manipulating extracellular calcium. Coanalysis of intracellular Ca2+ levels and CaMKII activity in the same population of eggs demonstrated a rapid and transient enzyme response to each increase in Ca2+. Enzyme activity increased 370% during the first Ca2+ rise, representing about 60% of maximal activity, and had decreased to basal levels within 5 min from the time Ca2+ reached its peak value. Single fertilized eggs monitored for Ca2+ had a mean increase in CaMKII activity of 185%. One and two ionomycin-induced Ca2+ transients resulted in 39 and 49% mean cortical granule (CG) loss, respectively, while CG exocytosis and resumption of meiosis were inhibited by a CaMKII antagonist. These studies demonstrate that changes in the level of Ca2+ and in CaMKII activity can be studied in the same cell and that CaMKII activity is exquisitely sensitive to experimentally induced oscillations of Ca2+ in vivo. The data support the hypothesis that CaMKII activity oscillates for a period of time after normal fertilization and temporally regulates many events of egg activation. (C) 2003 Elsevier Science (USA). All rights reserved.