蛋白激酶A对小鼠受精卵早期发育过程中M期促进因子活性的影响

为研究小鼠体内 1 细胞期受精卵M期蛋白激酶A(PKA)对M期促进因子 (MPF)活性的影响 ,应用PKA激动剂cAMP及热稳定性抑制剂PKI显微注射入 1 细胞期受精卵内 ,观察MPF及PKA活性变化 .未经注射的对照组MPF活性在分裂期增高 ,分裂间期下降 ;而PKA活性在进入分裂期下降 ,分裂间期升高 .cAMP组PKA活性维持高峰值 ,直至注射HCG后 2 8h ,MPF活性高峰延迟 30min出现 ;PKI显微注射组PKA活性低 ,而MPF活性在注射HCG后 2 7 5h即达高峰 ,且维持高峰时间达1 5h .结果表明 ,PKA活性在细胞周期中也呈波动性 ,间期活性高 ,分裂期活性低 ;PKA高活性抑制MPF活性 ,而抑制PKA活性则MPF活性高峰提前出现 .

Effect of Protein Kinase A on M-Phase Promoting Factor Activity in EarlyDevelopment of Mouse Fertilized Eggs

The cAMP dependent protein kinase (PKA) stimulator cAMP and thermal stable inhibitor PKI (protein kinase A inhibitor) were microinjected into mouse 1-cell stage fertilized eggs in order to study the effect of PKA on M-phase promoting factor (MPF) activity and cell cycle progression.For the control group,MPF activity began to rise at 27\^5 hours after adding HCG,after 0\^5 hours reached to a plateau of about 1 hour and then decreased rapidly.The PKA activity sustained a high level during the interphase before 27 hours and after 29 hours after adding HCG and low during M phase (28—29 hours after adding HCG).In the cAMP group,PKA activity sustained a high level at the first 28 hours and the MPF activity reached to a high plateau after 30 min.In the PKI group,the PKA activity was low in the period from 27 hours to 29 hours,but the MPF activity reached to a high value at 27\^5 hours and lasted for 1\^5 hours at that level.These results showed that both the activities of PKA and MPF oscillated during the cell cycle.PKA activity was high during interphase and low during M phase,stimulation of PKA induced interphase arrest preventing the activation of the M phase promoting factor.Inhibition of endogenous PKA in interphase increased MPF activity,hastened the onset of mitosis.