Degradation of hsp70 and other mRNAs in Drosophila via the 5′-3′ pathway and its regulation by heat shock
Degradation of hsp70 and other mRNAs in Drosophila via the 5′-3′ pathway and its regulation by heat shock
复制标题
DOI：
10.1074/jbc.m702998200
复制
发表时间：
2007-07-27
影响因子：
4.8
通讯作者：
Wahle, Elmar
中科院分区：
文献类型：
--
作者：
Boenisch, Clemens;Temme, Claudia;Wahle, Elmar
酵母中有两种常见的信使核糖核酸衰变途径。两者都是以去烯基化开始的。主要途径是通过帽水解和5‘-核外降解进行，而次要途径是3’-核外降解，然后是剩余的帽结构的水解。在高等真核生物中，这些信使核糖核酸衰变的途径被认为是保守的，但还没有得到很好的描述。我们研究了果蝇施耐德细胞中HSP70mRNA的衰变。报告结构的使用表明，该mRNA的快速去烯化是由其3‘-非翻译区指导的。主要的死烯基酶是CCR4中心点，而不是复合体；泛核酸酶的贡献较小。热休克不仅可以阻止HSP70的去烯化，还可以阻止主体mRNA的去烯化。一个完全无烯基化的带帽的HSP70信使核糖核酸衰变中间体瞬间积累，并通过帽状水解物和5‘-衰变被降解。因此，摘除是退化过程中缓慢的一步。在热休克过程中，帽的水解度也受到抑制。来自3‘端的报告RNA的降解只有在抑制5’-衰变时才能检测到，因此代表了一条轻微的衰变途径。由于两个报告RNA和至少两个内源RNA主要从5‘端降解，帽水解是一个缓慢的步骤，这一途径似乎对果蝇mRNA的衰退具有普遍的重要性。
Two general pathways of mRNA decay have been characterized in yeast. Both start with deadenylation. The major pathway then proceeds via cap hydrolysis and 5'-exonucleolytic degradation whereas the minor pathway consists of 3'-exonucleolytic decay followed by hydrolysis of the remaining cap structure. In higher eukaryotes, these pathways of mRNA decay are believed to be conserved but have not been well characterized. We have investigated the decay of the hsp70 mRNA in Drosophila Schneider cells. As shown by the use of reporter constructs, rapid deadenylation of this mRNA is directed by its 3'-untranslated region. The main deadenylase is the CCR4 center dot NOT complex; the PAN nuclease makes a lesser contribution. Heat shock prevents deadenylation not only of the hsp70 but also of bulk mRNA. A completely deadenylated capped hsp70 mRNA decay intermediate accumulates transiently and is degraded via cap hydrolysis and 5'-decay. Thus, decapping is a slow step in the degradation pathway. Cap hydrolysis is also inhibited during heat shock. Degradation of reporter RNAs from the 3'-end became detectable only upon inhibition of 5'-decay and thus represents a minor decay pathway. Because two reporter RNAs and at least two endogenous mRNAs were degraded primarily from the 5'-end with cap hydrolysis as a slow step, this pathway appears to be of general importance for mRNA decay in Drosophila.