钙离子和冈田酸对亚胺环己酮诱导小鼠卵子孤雌激活的影响

摘要

M Ⅱ mouse eggs can be released from M Ⅱ arrest by various physical and chemical stimuli. Cycloheximide(CHX), a protein synthesis inhibitor, can activate mouse eggs but the underlying mechanism is not fully known. Previousstudies suggest that CHX activation occurs through the inhibition of MOS (a Ser/Thr protein kinase) synthesis. In thisexperiment, mouse eggs were cultured in a medium containing various reagents, including cycloheximide, Ca2 + ionophoreA23187 and Ca2+ chelator. The results show that the parthenogenetic activation of mouse eggs by CHX was calcium-de-pendent, and was enhanced by A23187. Egg activation induced by CHX + A23187 was suppressed by okadaic acid, andMAP kinase dephosphorylation was partially reversed as well. Our results suggest that inhibition of MOS synthesis maynot be the only mechansism by which CHX induces egg activation and that such egg activation can be blocked by proteinphosphotase inhibition.%哺乳动物卵母细胞在排卵后停滞在第二次减数分裂中期,受精和多种物理或是化学刺激可以克服这一阻滞使卵母细胞活化.蛋白合成抑制剂亚胺环己酮可以诱导小鼠卵母细胞发生孤雌活化,但其机制尚未完全阐明.以前的研究提示亚胺环己酮可能是通过抑制蛋白激酶MOS的合成来发挥孤雌激活的作用的.本实验发现,CHX诱导的卵母细胞孤雌活化是Ca2+依赖性的,其效率可被钙离子载体A23187大大提高.免疫蛋白印迹结果表明,卵母细胞孤雌活化后MAPK发生去磷酸化.蛋白磷酸酶抑制剂冈田酸可以克服CHX+A23187对小鼠卵母细胞活化作用,并且部分阻止MAPK去磷酸化.以上结果表明,抑制MOS的合成并非CHX诱导的孤雌活化过程的惟一原因,并且蛋白磷酸酶抑制剂可以阻断这一激活事件.