Jung T, Lee C, Moor R M
Institute of Animal Physiology and Genetics Research, Department of Molecular Embryology, Babraham, Cambridge, UK.
Reprod Nutr Dev. 1992;32(5-6):461-73. doi: 10.1051/rnd:19920506.
Normal oocyte maturation depends on signal transmission between granulosa cells and the oocyte. We have analysed the effects of inhibiting (I) cyclic AMP-dependent protein kinase (protein kinase A, PK-A), (II) Ca2+/phospholipid-dependent protein kinase (protein kinase C, PK-C) and (III) calmodulin (CaM) on pig oocyte maturation in vitro, protein synthesis and phosphorylation. The inhibition of PK-A using a specific inhibitor H8, decreased the maturation rate (rate of germinal vesicle breakdown, GVBD) of cumulus-enclosed pig oocytes in a dose-dependent manner by approximately 12%, reaching a plateau at 100 microM. The inhibition of PK-C with H7, an inhibitor with some side-effects on PK-A, decreased the maturation rate of cumulus-enclosed oocytes in a dose-dependent manner to a maximum of 20% at a concentration of 100 microM. The calmodulin antagonist W7 up to a concentration of 200 microM had no effects on maturation of cumulus-enclosed pig oocytes. None of the inhibitors (H7, H8 and W7) altered the patterns of protein synthesis of either pig oocytes and cumulus cells after maturation in vitro. Oocyte phosphoprotein patterns were, however, clearly changed by W7. Cumulus cell protein phosphorylation patterns were changed by all 3 agents. Since inhibition of cyclic AMP and Ca2+ phospholipid pathways by PK-A and PK-C blocking chemicals affected only a limited proportion of oocytes (12 and 20%, respectively) and inhibition of Ca2+ binding to CaM was without effect on oocyte maturation, we conclude that these pathways modulate rather than regulate oocyte maturation in the pig.
正常的卵母细胞成熟依赖于颗粒细胞与卵母细胞之间的信号传递。我们分析了抑制（I）环磷酸腺苷依赖性蛋白激酶（蛋白激酶A，PK-A）、（II）Ca2+/磷脂依赖性蛋白激酶（蛋白激酶C，PK-C）和（III）钙调蛋白（CaM）对猪卵母细胞体外成熟、蛋白质合成及磷酸化的影响。使用特异性抑制剂H8抑制PK-A，以剂量依赖性方式使卵丘包裹的猪卵母细胞的成熟率（生发泡破裂率，GVBD）降低了约12%，在100 microM时达到平台期。使用对PK-A有一些副作用的抑制剂H7抑制PK-C，以剂量依赖性方式使卵丘包裹的卵母细胞成熟率降低，在浓度为100 microM时最大降低20%。钙调蛋白拮抗剂W7浓度高达200 microM时，对卵丘包裹的猪卵母细胞成熟没有影响。在体外成熟后，这些抑制剂（H7、H8和W7）均未改变猪卵母细胞和卵丘细胞的蛋白质合成模式。然而，W7明显改变了卵母细胞磷蛋白模式。所有3种试剂均改变了卵丘细胞蛋白磷酸化模式。由于通过PK-A和PK-C阻断化学物质抑制环磷酸腺苷和Ca2+磷脂途径仅影响有限比例的卵母细胞（分别为12%和20%），且抑制Ca2+与CaM结合对卵母细胞成熟没有影响，我们得出结论，这些途径调节而非调控猪的卵母细胞成熟。
