Involvement of Ca2+-dependent proteasome in the degradation of both cyclin B1 and Mos during spontaneous activation of matured rat oocytes
Involvement of Ca2+-dependent proteasome in the degradation of both cyclin B1 and Mos during spontaneous activation of matured rat oocytes
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DOI：
10.1016/j.theriogenology.2006.08.012
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发表时间：
2007-02-01
期刊：
影响因子：
2.8
通讯作者：
Hirabayashi, Masumi
中科院分区：
文献类型：
--
作者：
Ito, Junya;Shimada, Masayuki;Hirabayashi, Masumi
在成熟的大鼠卵母细胞中，中期II期(MII)的自发激活发生在从输卵管采集后。众所周知，丝裂原活化蛋白激酶(MAPK)途径和p34(Cdc2)激酶在其他物种的MII停滞中起着重要作用。然而，没有关于这些因素在不同品系的老鼠之间的差异的信息。在本研究中，Wistar大鼠自发激活的卵母细胞中，MOS蛋白水平和MAPK/MAPK活性在120min时降低(分别为13.8、25.7和19.3，P<0.05)，而非自发激活的SD卵母细胞具有较高的MOS蛋白水平和MEK/MAPK活性(分别为75.9、76.2和87.9，P<；0.05)。在60min时，MEK抑制剂U0126显著抑制SD卵母细胞中MAPK的磷酸化；这种处理通过降解细胞周期蛋白B1而降低p34(Cdc2)的活性，并呈时间依赖性。蛋白酶体抑制剂MG132或钙离子螯合剂BAPTA-AM以剂量依赖的方式克服了MOS和Cyclin 131在Wistar卵母细胞中的自发降解。用BAPTA-AM处理的Wistar卵母细胞，90%以上的卵母细胞在MII中滞留到120min。总之，携带Mos/MEK/MAPK的SD卵母细胞通过稳定细胞周期蛋白B1来维持p34(Cdc2)的高活性，从而参与其减数分裂停滞。相比之下，Wistar卵母细胞的细胞抑制因子活性相对较低；MOS/MEK/MAPK的快速下降不能稳定Cyclin B1和MOS，这些卵母细胞可能会自发激活。(C)2006 Elsevier Inc.保留所有权利。
In matured rat oocytes, spontaneous activation from the metaphase-II (MII) stage occurred after collection from the oviducts. It is well known that the mitogen-activated protein kinase (MAPK) pathway and p34(cdc2) kinase play an important role in the arrest at MII in other species. However, there is no information about the difference in these factors among strains of rats. In the present study, in spontaneously activated oocytes from the Wistar rat, the Mos protein level and the activity of MAPK kinase (MEK)/MAPK were decreased at 120 min (13.8, 25.7, and 19.3, respectively, P < 0.05), whereas Sprague-Dawley (SD) oocytes, which were not spontaneously activated, had a high level of Mos protein and MEK/MAPK activity (75.9, 76.2, and 87.9, respectively, P < 0.05). Phosphorylation of MAPK in the SD oocytes was significantly suppressed by MEK inhibitor, U0126 at 60 min; this treatment decreased p34(cdc2) kinase activity via cyclin B I degradation in a time-dependent manner. The treatment with proteasome inhibitor, MG132 or Ca2+-chelator, BAPTA-AM, overcame the spontaneous degradation of both Mos and cyclin 131 in a dose-dependent manner in Wistar oocytes. More than 90% of Wistar oocytes treated with BAPTA-AM were arrested at MII until 120 min. In conclusion, SD oocytes carrying Mos/MEK/MAPK, maintained a high activity of p34(cdc2) kinase by stabilizing cyclin B1, thus involved in their meiotic arrest. In contrast, Wistar oocytes had a relatively low cytostatic factor activity; rapid decrease of Mos/ MEK/MAPK failed to stabilize both cyclin B1 and Mos, and these oocytes were likely to spontaneously activate. (c) 2006 Elsevier Inc. All rights reserved.