Diminished surface clustering and increased perinuclear accumulation of large conductance Ca2+-activated K+ channel in mouse myometrium with pregnancy
Diminished surface clustering and increased perinuclear accumulation of large conductance Ca2+-activated K+ channel in mouse myometrium with pregnancy
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DOI：
10.1074/jbc.m306564200
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发表时间：
2003-11-14
影响因子：
4.8
通讯作者：
Stefani, E
中科院分区：
文献类型：
--
作者：
Eghbali, M;Toro, L;Stefani, E
大电导钙激活的K+通道在调节子宫肌层收缩中起着关键作用。与未孕大鼠相比，晚孕大鼠子宫肌层中它们的电流密度、信使核糖核酸和总蛋白显著降低。与大鼠相反，小鼠妊娠晚期通道mRNA和总蛋白增加，电流密度降低。在这里，我们研究了这些差异的机制。实时定量聚合酶链式反应和免疫印迹显示，在妊娠晚期，大鼠的通道转录量和总蛋白减少，而小鼠的通道转录量和总蛋白上调。对单个心肌细胞的高分辨率共聚焦显微镜显示，在未怀孕的小鼠中，通道在表面膜上呈簇状表达。在妊娠晚期，虽然通道蛋白总体上有所增加，但大部分聚集在核周细胞器中，通道聚集几乎从细胞膜表面消失。这与大鼠子宫肌层形成对比，在那里，通道转录和包括表面膜在内的整体蛋白质水平减少。我们的结论是，大电导钙激活的K+通道表面表达在妊娠晚期的大鼠和小鼠子宫肌层中均减少。然而，在大鼠中，细胞表面通道表达减少的主要机制是转录减少，而在小鼠中，它是到细胞表面的改变的交通。
Large conductance Ca2+-activated K+ channels play a critical role in regulating myometrium contractility. Their current density, mRNA, and total protein are greatly diminished in myometrium of late pregnant rats versus nonpregnant animals. Opposite to rats, in mice, channel mRNA and total protein increase in late pregnancy, but current density decreases as in rats. Here, we investigated the mechanism of these differences. Real time PCR and Western blots demonstrate that, in late pregnancy, channel transcript quantities and total protein were diminished in rats but up-regulated in mice. High resolution confocal microscopy of single myocytes showed that, in nonpregnant mice, channels were expressed in clusters at the surface membrane. In late pregnancy, although there was an overall increase in channel protein, its majority was accumulated in perinuclear organelles, and channel clustering practically disappeared from the surface membrane. This contrasts with rat myometrium, where there is a reduction of channel transcripts and overall protein levels including the surface membrane. We conclude that large conductance Ca2+-activated K+ channel surface expression is reduced in both rat and mouse late pregnant myometrium. However, in rats, the main mechanism for the reduced channel expression at the cell surface is a diminished transcription, whereas in mice, it is an altered traffic to the surface.