Interspersed poly(A) RNAs of amphibian oocytes are not translatable.
Interspersed poly(A) RNAs of amphibian oocytes are not translatable.
复制标题
两栖类卵母细胞中散布的聚腺苷酸RNA (poly(A) RNA) 不可翻译。
DOI：
10.1016/0022-2836(84)90191-8
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发表时间：
1984
影响因子：
5.6
通讯作者：
Davidson,EH
中科院分区：
文献类型：
--
作者：
Richter,JD;Smith,LD;Anderson,DM;Davidson,EH
爪蟾细胞的多聚（A）RNA已被证明包括单拷贝和散布的转录物。散布的母体 Poly(A) RNA 含有分布在由单拷贝序列转录的区域内的重复序列元件。当复性时，这些 RNA 形成部分双链 RNA 网络，如前所述，这可用于将散布的母本转录本与复性后仍保持单链的母本转录本进行制备性分离 (Andersonet al., 1982)。这些 RNA 片段的翻译活性在体外、小麦胚芽和网织红细胞系统中进行了测试。虽然单链部分支持蛋白质合成，但散布的卵母细胞 RNA 表现出很少的翻译活性。通过注射到爪蟾母细胞体内测量翻译活性。向先前注射珠蛋白mRNA的卵母细胞注射逐渐增加量的单链、双链或变性双链RNA级分，并测定珠蛋白合成的量。研究发现，单链 RNA 与珠蛋白 mRNA 竞争卵母细胞有限的翻译装置，这表现为珠蛋白合成的数量减少。然而，当注射复性或变性形式的双链RNA时，珠蛋白合成不受影响。我们得出的结论是，散布的 RNA 不在卵母细胞内翻译。还测定了注射卵母细胞中多核糖体上加载的单链和双链 RNA 的量。在注射的卵母细胞中，67% 的放射性碘单链 RNA 与多聚核糖体一起沉淀，而不到 20% 的类似标记的双链 RNA 与多聚核糖体一起沉淀。该值与注射部分水解的RNA时获得的值相似，再次表明散布的RNA基本上没有在体内被翻译。讨论了这些发现在卵子发生和早期发育过程中与翻译调控相关的重要性。
The poly(A) RNA of theXenopusoocytes has been shown to include both single copy and interspersed transcripts. Interspersed maternal poly(A) RNAs contain repetitive sequence elements distributed within regions transcribed from single copy sequences. When renatured these RNAs form partially double-stranded RNA networks, and as shown earlier this can be utilized for preparative separation of interspersed maternal transcripts from maternal transcripts that remain single-stranded after renaturation (Andersonet al., 1982). The translational activity of these RNA fractions was testedin vitro, in wheat germ and reticulocyte systems. While the single-stranded fractions supported protein synthesis, the interspersed oocyte RNAs displayed little translational activity. Translational activity was measuredin vivoby injection into theXenopusoocyte. Oocytes previously injected with globin mRNA were injected with increasing amounts of single-stranded, double-stranded, or denatured double-stranded RNA fractions, and the amount of globin synthesis was determined. It was found that single-stranded RNA competes with globin mRNA for the limited translational apparatus of the oocyte, as manifested by a quantitative reduction of globin synthesis. However, globin synthesis was not affected when double-stranded RNA, either in renatured or denatured form, was injected. We conclude that the interspersed RNAs are not translated within the oocyte. The amount of single and double-stranded RNAs loaded onto polysomes in the injected oocytes was also determined. Sixty seven per cent of radio-iodinated single-stranded RNA pelleted with polysomes in injected oocytes, whereas less than 20% of similarly labeled double-stranded RNA pelleted with polysomes. This value is similar to that obtained when partially hydrolyzed RNA is injected, suggesting again that essentially none of the interspersed RNA is translatedin vivo. The significance of these findings in relation to translational regulation during oogenesis and early development is discussed.