Cytoplasmic polyadenylation elements mediate masking and unmasking of cyclin B1 mRNA
Cytoplasmic polyadenylation elements mediate masking and unmasking of cyclin B1 mRNA
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DOI：
10.1093/emboj/18.8.2294
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发表时间：
1999-04-15
期刊：
影响因子：
11.4
通讯作者：
Richter, JD
中科院分区：
文献类型：
--
作者：
de Moor, CH;Richter, JD
在卵母细胞成熟过程中，细胞周期蛋白B1 mRNA被细胞质聚腺苷酸化激活。这一过程依赖于mRNA 3'非翻译区（UTR）的胞质聚腺苷化元件（cpe）。为了确定一个可滴定的因子是否可能参与该mRNA的初始翻译抑制（掩蔽），将高水平的细胞周期蛋白B1 3' UTR注射到卵母细胞中。虽然该处理对内源性细胞周期蛋白B1 mRNA的多(A)尾长度没有影响，但它诱导了细胞周期蛋白B1的合成。突变分析显示，cyclin 3' UTR中最有效的揭膜元件是CPE。然而，其他在结构上与CPE相似但不结合CPE结合的聚腺苷化因子CPEB的富u序列，未能诱导揭露。当细胞周期蛋白B1 3' UTR融合到氯霉素乙酰转移酶（CAT）编码区时，细胞周期蛋白B1 3' UTR抑制了注射卵母细胞中CAT的翻译。此外，含有多个CPE拷贝的合成3' UTR也抑制翻译，并且以剂量依赖的方式起作用。此外，有效的cpe介导的屏蔽需要帽依赖翻译。在黄体酮诱导的正常成熟过程中，胞质聚腺苷化是mRNA去掩蔽所必需的。提出了一个模型来解释CPE如何调节细胞周期蛋白B1 mRNA的掩蔽和解除掩蔽。
During oocyte maturation, cyclin B1 mRNA is translationally activated by cytoplasmic polyadenylation. This process is dependent on cytoplasmic polyadenylation elements (CPEs) in the 3' untranslated region (UTR) of the mRNA. To determine whether a titratable factor might be involved in the initial translational repression (masking) of this mRNA, high levels of cyclin B1 3' UTR were injected into oocytes. While this treatment had no effect on the poly(A) tail length of endogenous cyclin B1 mRNA, it induced cyclin B1 synthesis. A mutational analysis revealed that the most efficient unmasking element in the cyclin 3' UTR was the CPE. However, other U-rich sequences that resemble the CPE in structure, but which do not bind the CPE-binding polyadenylation factor CPEB, failed to induce unmasking. When fused to the chloramphenical acetyl transferase (CAT) coding region, the cyclin B1 3' UTR inhibited CAT translation in injected oocytes. In addition, a synthetic 3' UTR containing multiple copies of the CPE also inhibited translation, and did so in a dose-dependent manner. Furthermore, efficient CPE-mediated masking required cap-dependent translation. During the normal course of progesterone-induced maturation, cytoplasmic polyadenylation was necessary for mRNA unmasking. A model to explain how cyclin B1 mRNA masking and unmasking could be regulated by the CPE is presented.