EFFECTS OF PROTEIN KINASE-C STIMULATION AND FREE CA-2+ RISE IN MAMMALIAN EGG ACTIVATION
EFFECTS OF PROTEIN KINASE-C STIMULATION AND FREE CA-2+ RISE IN MAMMALIAN EGG ACTIVATION
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DOI：
10.1002/mrd.1120240205
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发表时间：
1989-10-01
期刊：
影响因子：
--
通讯作者：
MANGIA, F
中科院分区：
文献类型：
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作者：
COLONNA, R;TATONE, C;MANGIA, F
已经在通过特异性PKC刺激剂如4 β-PKC激活剂孤雌激活的小鼠卵中研究了蛋白磷酸化活性、染色体分离和皮质颗粒胞吐作用（CGE）。佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA）和1-油基-2-乙酰基甘油（OAG），或通过诱导细胞溶质钙浓度（[Ca 2 +]i）立即增加的试剂，如乙醇和Ca-离子载体A23187。当在不同活化处理后10分钟分析小鼠卵的蛋白磷酸化活性时，32 kDa多肽的磷酸化是所使用的所有不同孤雌生殖剂的共同特征。这种标记的出现与[Ca 2 +]i的增加无关，如通过1）用fura-2直接测量胞质Ca 2+浓度和2）外源Ca 2+进入激活的卵所指示的。在PMA引起的孤雌生殖细胞中，第二极体的发射被阻断，而在OAG处理的卵中，第二极体的发射显然是正常的，除非卵连续暴露于OAG。CGE几乎是立即在乙醇激活的鸡蛋，但在PMA处理的细胞，它发生显着晚，与时间相对应的发现在这个系统中持续的Ca 2+振荡的外观。在这里，我们提出，在哺乳动物卵1）PKC刺激代表了早期的调节步骤，在卵激活; 2）这种激酶活性关闭前第二次减数分裂分裂;和3）胞质游离Ca 2+的上升是必不可少的CGE的发生。
Protein phosphorylation activity, chromosome segregation, and cortical granule exocytosis (CGE) have been studied in mouse eggs activated parthenogenetically by specific PKC stimulators such as 4.beta.-phorbol 12-myristate 13-acetate (PMA) and 1-oleyl-2-acetylglycerol (OAG), or by agents inducing an immediate increase in cytosolic calcium concentration ([Ca2+]i) such as ethanol and Ca-ionophore A23187. When protein phosphorylation activity of mouse eggs was analyzed 10 min after different activation treatments, the phosphorylation of a 32 kDa polypeptide was a feature common to all different parthenogentic agents used. The appearance of such labeling was independent of an increasing [Ca2+]i, as indicated by direct measurements of 1) cytosolic Ca2+ concentration with fura-2 and 2) exogenous Ca2+ entrance into activated eggs. Emission of the second polar body was blocked in PMA-elicited parthenogenones, whereas it was apparently normal in OAG-treated eggs, unless the eggs were continuously exposed to OAG. CGE was almost immediate in ethanol-activated eggs, but in PMA-treated cells, it occurred significantly later, with a timing corresponding to that found for the appearance of sustained Ca2+ oscillations in this system. Here, we propose that in mammalian eggs 1) PKC stimulation represents an early regulatory step in egg activation; 2) this kinase activity is turned off before the second meiotic cleavage; and 3) cytosolic free Ca2+ rise is essential for CGE occurrence.