Phosphorylation of inositol 1,4,5-triphosphate receptor 1 during in vitro maturation of porcine oocytes
Phosphorylation of inositol 1,4,5-triphosphate receptor 1 during in vitro maturation of porcine oocytes
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DOI：
10.1111/j.1740-0929.2009.00699.x
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发表时间：
2010-01-01
影响因子：
2
通讯作者：
Kashiwazaki, Naomi
中科院分区：
文献类型：
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作者：
Ito, Junya;Yoshida, Tomoko;Kashiwazaki, Naomi
在哺乳动物受精过程中，精子诱导的细胞内 Ca2+ 信号 ([Ca2+](i)) 介导减数分裂的退出和卵母细胞的激活。最近，我们在小鼠卵母细胞中证明，肌醇 1,4,5 三磷酸受体 1 型 (IP(3)R1)（负责受精过程中 Ca2+ 释放和振荡的通道）的磷酸化水平在成熟和受精过程中发生变化。因此，我们检测了猪卵母细胞体外成熟过程中IP(3)R1的表达和磷酸化。在这里，我们目前的研究表明，IP(3)R1 蛋白的表达在成熟过程中没有变化，尽管受体的磷酸化状态，特别是 MPM-2 表位的磷酸化状态发生了变化。我们发现，虽然在成熟开始时IP(3)R1缺乏MPM-2免疫反应性，但它在24小时时变得具有MPM-2反应性，并在36小时时达到最大反应性。有趣的是，MPM-2 反应性的获得与 p34(cdc2) 激酶和丝裂原激活蛋白激酶 (MAPK) 的激活同时发生，它们参与减数分裂进程。成熟完成后，U0126 灭活 MAPK 并不影响 IP(3)R1 磷酸化，尽管 roscovitine 灭活 p34(cdc2) 激酶显着降低 IP(3)R1 磷酸化。两种抑制剂均不影响 IP(3)R1 的总表达。总而言之，我们的结果表明 IP(3)R1 在成熟过程中经历动态磷酸化，这可能是受精时振荡产生的基础。
During fertilization in mammalian species, a sperm-induced intracellular Ca2+ signal ([Ca2+](i)) mediates both exit of meiosis and oocyte activation. Recently, we demonstrated in mouse oocytes that the phosphorylation levels of inositol 1,4,5 trisphosphate receptor type1 (IP(3)R1), the channel responsible for Ca2+ release and oscillations during fertilization, changed during maturation and fertilization. Therefore, we examined the expression and phosphorylation of IP(3)R1 during in vitro maturation of pig oocytes. Here, our present study shows that expression of IP(3)R1 protein did not change during maturation, although the phosphorylation status of the receptor, specifically at an MPM-2 epitope, did. We found that while at the beginning of maturation IP(3)R1 lacked MPM-2 immunoreactivity, it became MPM-2 reactive by 24 h and reached maximal reactivity by 36 h. Interestingly, the acquisition of MPM-2 reactivity coincided with the activation of p34(cdc2) kinase and mitogen-activated protein kinase (MAPK), which are involved in meiotic progression. Following completion of maturation, inactivation of MAPK by U0126 did not affect IP(3)R1 phosphorylation, although inactivation of p34(cdc2) kinase by roscovitine dramatically reduced IP(3)R1 phosphorylation. Neither inhibitor affected total expression of IP(3)R1. Altogether, our results show that IP(3)R1 undergoes dynamic phosphorylation during maturation and this might underlie the generation of oscillations at fertilization.