Neomycin, an inhibitor of phosphoinositide hydrolysis, inhibits the resumption of bovine oocyte spontaneous meiotic maturation.
Neomycin, an inhibitor of phosphoinositide hydrolysis, inhibits the resumption of bovine oocyte spontaneous meiotic maturation.
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新霉素是磷酸肌醇水解抑制剂，可抑制牛卵母细胞自发减数分裂成熟的恢复。
DOI：
10.1002/jez.1402580111
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Homa,ST
中科院分区：
文献类型：
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作者：
Homa,ST
研究了肌醇磷脂水解产生的细胞内信号参与调控牛卵母细胞自发减数分裂恢复的可能性。大量采集卵母细胞，在添加0.5%牛血清白蛋白的2A-Bmoc培养液中，加入或不加入新霉素(磷脂酰肌醇水解酶的抑制剂)或佛波醇酯(蛋白激酶C的激活剂)。在培养前用BAPTA/AM(一种钙离子螯合剂)预负荷来检测细胞内钙的作用。对减数分裂成熟进行细胞遗传学评分。1)新霉素对生发泡破裂有不可逆的抑制作用，抑制作用不超过60%，且在5 mM或以上浓度时明显。在2.5 mM或更高的浓度下，减数分裂超过中期I的进程被抑制。新霉素只有在卵泡释放后3h内进入卵母细胞才能完全发挥作用，但在对照条件下培养9h才能观察到生发泡破裂。2)PMA单独作用对生发泡破裂无明显影响，但与2 mM IBMX协同作用可抑制生发泡破裂。PMA对卵母细胞中期I以后的减数分裂进程具有双重作用：1 nM PMA具有刺激作用，而1μM PMA则抑制卵母细胞达到后期I或以后的能力。这些观察结果在非肿瘤促进剂佛波酯中没有发现。3)不添加外源钙对减数分裂的自发恢复无显著影响。然而，预先加载BAPTA/AM的卵母细胞显示出剂量依赖的抑制生发泡破裂的作用，即使在细胞外钙存在的情况下也是如此。这些结果为肌醇磷脂代谢在牛卵母细胞成熟中的作用提供了间接证据；提示细胞内钙动员是减数分裂恢复的先决条件，蛋白激酶C可能调节cAMP依赖的抑制这一反应。
The possibility that the intracellular signals generated upon phosphoinositide hydrolysis are involved in regulating bovine oocyte spontaneous meiotic resumption was investigated. Oocytes were mass‐harvested and cultured in 2A‐BMOC medium supplemented with 0.5% bovine serum albumin in the presence or absence of neomycin (an inhibitor of phosphoinositide hydrolysis) or phorbol myristate acetate (an activator of protein kinase C). The role of intracellular calcium was examined by preloading with BAPTA/AM (a calcium chelator) prior to culture. Meiotic maturation was scored cytogenetically. 1) Neomycin induces an irreversible inhibition of germinal vesicle breakdown which does not exceed 60% and is apparent at concentrations of 5 mM or above. Progression of meiosis past metaphase I is inhibited at concentrations of 2.5 mM or above. The full effect of neomycin is only apparent if it is presented to the oocytes within 3 h of follicular release, although germinal vesicle breakdown is not observed until 9 h culture under control conditions. 2) PMA alone has negligible effect on germinal vesicle breakdown, but it acts synergistically with 2 mM IBMX to inhibit this process. PMA has a dual effect on the progression of meiosis past metaphase I: 1 nM PMA has a stimulatory effect while 1 μM PMA blocks the ability of oocytes to reach anaphase I or beyond. These observations are not found with a non‐tumor‐promoting phorbol ester. 3) Spontaneous meiotic resumption is not significantly affected in the absence of added exogenous calcium. However, oocytes preloaded with BAPTA/AM exhibit a dose‐dependent inhibition of germinal vesicle breakdown, even in the presence of extracellular calcium. These results provide indirect evidence for a role for phosphoinositide metabolism in bovine oocyte maturation; it is suggested that intracellular calcium mobilization is prerequisite for meiotic resumption and protein kinase C may modulate cAMP‐dependent inhibition of this response.