ON THE SYNTHESIS AND DESTRUCTION OF A-TYPE AND B-TYPE CYCLINS DURING OOGENESIS AND MEIOTIC MATURATION IN XENOPUS-LAEVIS
ON THE SYNTHESIS AND DESTRUCTION OF A-TYPE AND B-TYPE CYCLINS DURING OOGENESIS AND MEIOTIC MATURATION IN XENOPUS-LAEVIS
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DOI：
10.1083/jcb.114.4.755
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发表时间：
1991-08-01
影响因子：
7.8
通讯作者：
HUNT, T
中科院分区：
文献类型：
--
作者：
KOBAYASHI, H;MINSHULL, J;HUNT, T
我们已经测量了周期蛋白mRNA和多肽的水平在卵子发生过程中，胆甾酮诱导的卵母细胞成熟，并立即在青蛙，非洲爪蟾卵激活后。从卵子发生的最早阶段直到受精后，每个卵母细胞中每种细胞周期蛋白的mRNA都以大约5 × 10（7）个分子的恒定水平存在。多肽的水平显示出更复杂的积累模式。B型细胞周期蛋白首先在IV期和V期卵母细胞中检测到。到VI期，细胞周期蛋白B2多肽约为2 × 10（9）分子/卵母细胞（150 pg）。孕酮处理后，数量增加，但GVBD后恢复到以前的水平，并没有进一步的变化，直到它被破坏受精。周期蛋白B1在VI期卵母细胞中以每个卵母细胞4 × 10（8）个分子的量存在，并在成熟过程中稳步上升，最终达到与未受精卵中的周期蛋白B2相似的水平。与B型细胞周期蛋白不同，周期蛋白A在VI期卵母细胞中几乎检测不到，并且只有在卵母细胞暴露于孕酮后才开始大量产生。在卵母细胞成熟过程中，细胞周期蛋白B1和B2也经历了翻译后修饰。孕激素强烈刺激细胞周期蛋白和p34 cdc 2的合成在这些卵母细胞，但尽管细胞周期蛋白的合成继续在鸡蛋和受精后，合成的p34 cdc 2 GVBD后强烈下降。这些结果的意义进行了讨论，在激活和失活的促成熟因子。
We have measured the levels of cyclin mRNAs and polypeptides during oogenesis, progesterone-induced oocyte maturation, and immediately after egg activation in the frog, Xenopus laevis. The mRNA for each cyclin is present at a constant level of approximately 5 x 10(7) molecules per oocyte from the earliest stages of oogenesis until after fertilization. The levels of polypeptides show more complex patterns of accumulation. The B-type cyclins are first detectable in stage IV and V oocytes. Cyclin B2 polypeptide is present at approximately 2 x 10(9) molecules (150 pg) per oocyte by stage VI. The amount increases after progesterone treatment, but returns to its previous level after GVBD and undergoes no further change until it is destroyed at fertilization. Cyclin B1 is present at 4 x 10(8) molecules per oocyte in stage VI oocytes, and rises steadily during maturation, ultimately reaching similar levels to cyclin B2 in unfertilized eggs. Unlike the B-type cyclins, cyclin A is barely detectable in stage VI oocytes, and only starts to be made in significant amounts after oocytes are exposed to progesterone. A portion of all the cyclins are destroyed after germinal vesicle breakdown (GVBD), and cyclins B1 and B2 also experience posttranslational modifications during oocyte maturation. Progesterone strongly stimulates both cyclin and p34cdc2 synthesis in these oocytes, but whereas cyclin synthesis continues in eggs and after fertilization, synthesis of p34cdc2 declines strongly after GVBD. The significance of these results is discussed in terms of the activation and inactivation of maturation-promoting factor.