The regulation of calcium/calmodulin-dependent protein kinase II during oocyte activation in the rat
The regulation of calcium/calmodulin-dependent protein kinase II during oocyte activation in the rat
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DOI：
10.1262/jrd.17047
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发表时间：
2006-06-01
影响因子：
1.8
通讯作者：
Hirabayashi, Masumi
中科院分区：
文献类型：
--
作者：
Ito, Junya;Kaneko, Ryosuke;Hirabayashi, Masumi
卵母细胞活化和随后的发育需要细胞内Ca2+的增加。钙调素依赖性蛋白激酶II（CaMKII）在卵母细胞激活中起着至关重要的作用。然而，CaMKII在此过程中如何调节尚未得到很好的表征。我们首次在大鼠卵母细胞中发现，卵母细胞激活过程中CaMKII被磷酸化。CaMKII磷酸化被CaMKII抑制剂KN 93抑制，但不被KN 92抑制，KN 92是KN 93的无活性类似物。电刺激大鼠卵母细胞导致细胞周期蛋白B和Mos的降解，推测是由于电脉冲诱导的Ca 2+升高。KN 93阻断了电脉冲诱导的两种蛋白质的降解。添加蛋白磷酸酶抑制剂冈田酸（OA）进一步增加了CaMKII的量，也增加了磷酸化酶的量。重要的是，在经历自发激活的卵母细胞中，CaMKII的积累和磷酸化也以时间依赖性方式发生。与此一致，添加KN 93抑制自发激活。总的来说，我们的研究结果表明，在卵母细胞活化过程中，CaMKII磷酸化，这种磷酸化参与失活的p34（cdc2）激酶，并在一定程度上参与降解的莫斯。此外，CaMKII磷酸化由蛋白磷酸酶负调控。
Increases in intracellular Ca2+ are required for oocyte activation and subsequent development. Calmodulin-dependent protein kinase II (CaMKII) plays a crucial role in oocyte activation. However, how CaMKII is regulated during this process is not well characterized. We show here for the first time in rat oocytes that CaMKII is phosphorylated during oocvte activation. CaMKII phosphorylation was suppressed by KN93, a CaMKII inhibitor, but not KN92, which is the inactive analogue of KN93. Electrical stimulation of rat oocytes resulted in degradation of both cyclin B and Mos, presumably due a rise in Ca2+ induced by the electrical pulse. KN93 blocked the degradation of both proteins induced by the electrical pulse. Addition of a protein phosphatase inhibitor, okadaic acid (OA), further increased the amount of CaMKII and also increased the amount of phosphorylated enzyme. Importantly, in oocytes undergoing spontaneous activation, accumulation and phosphorylation of CaMKII also occurs in a time-dependent manner. Consistent with this, addition of KN93 inhibited spontaneous activation. Collectively, our results show that CaMKII is phosphorylated during oocyte activation and that this phosphorylation is involved in inactivation of p34(cdc2) kinase and somewhat involved in degradation of Mos. Furthermore, CaMKII phosphorylation is negatively regulated by a protein phosphatase.