Translation of nonSTOP mRNA is repressed post-initiation in mammalian cells
Translation of nonSTOP mRNA is repressed post-initiation in mammalian cells
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DOI：
10.1038/sj.emboj.7601679
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发表时间：
2007-05-02
期刊：
影响因子：
11.4
通讯作者：
Pelletier, Jerry
中科院分区：
文献类型：
--
作者：
Akimitsu, Nobuyoshi;Tanaka, Junichi;Pelletier, Jerry
我们研究了哺乳动物细胞中缺乏框内终止密码子的异常mRNA（称为nonSTOP mRNA）的命运。我们发现，nonSTOP mRNA的翻译受到相当大的抑制，虽然没有观察到相应的mRNA减少。抑制似乎是在起始后，因为（i）受抑制的nonSTOP mRNA与多聚核糖体相关，（ii）IRES启动的和未加帽的nonSTOP mRNA的翻译受到抑制，（iii）当用于编程体外径流翻译测定时，与多聚核糖体相关的nonSTOP mRNA的蛋白质产生显著减少。与编码终止密码子的对照mRNA相比，非停止mRNA分布在较轻的多核糖体部分中，并且在非停止RNA的体外翻译过程中产生了大量的异源多肽，这表明翻译非停止mRNA的核糖体提前终止。此外，使用马尿酸和RNA酶保护试验的径流翻译试验表明，在nonSTOP mRNA的30末端存在核糖体停滞。综上所述，这些数据表明，核糖体在nonSTOP mRNA的30端停滞可以通过阻止上游翻译事件来阻断翻译。
We investigated the fate of aberrant mRNAs lacking in- frame termination codons (called nonSTOP mRNA) in mammalian cells. We found that translation of nonSTOP mRNA was considerably repressed although a corresponding reduction of mRNA was not observed. The repression appears to be post-initiation since (i) repressed nonSTOP mRNAs were associated with polysomes, (ii) translation of IRES-initiated and uncapped nonSTOP mRNA were repressed, and (iii) protein production from nonSTOP mRNA associating with polysomes was significantly reduced when used to program an in vitro run-off translation assay. NonSTOP mRNAs distributed into lighter polysome fractions compared to control mRNAs encoding a stop codon, and a significant amount of heterogeneous polypeptides were produced during in vitro translation of nonSTOP RNAs, suggesting premature termination of ribosomes translating nonSTOP mRNA. Moreover, a run-off translation assay using hippuristanol and RNAse protection assays suggested the presence of a ribosome stalled at the 30 end of nonSTOP mRNAs. Taken together, these data indicate that ribosome stalling at the 30 end of nonSTOP mRNAs can block translation by preventing upstream translation events.