3′ Terminal oligo U-tract-mediated stimulation of decapping
3′ Terminal oligo U-tract-mediated stimulation of decapping
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DOI：
10.1261/rna.765807
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发表时间：
2007-12-01
期刊：
影响因子：
4.5
通讯作者：
Kiledjian, Megerditch
中科院分区：
文献类型：
--
作者：
Song, Man-Gen;Kiledjian, Megerditch
Decapping is a critical step in the control of gene expression and is regulated by both positive and negative trans factors. Less is known about cis elements that promote decapping. In plants, following microRNA (miRNA)-directed cleavage of an mRNA, a uridine tract can be added onto the exposed 39 end of the resulting 59 fragment, which can promote 59 end decay. We now demonstrate that in mammalian cell extract, addition of five uridine residues to the 39 end of an RNA (U-5) promotes decapping relative to an RNA lacking the uridines (U-0). Although the decapping stimulation observed in extract required hDcp2, recombinant hDcp2 was unable to support differential decapping of the U-0 and U-5 RNAs, indicating that the stimulation was likely due to an indirect recruitment of hDcp2 to the RNA. Consistent with the promotion of 59 end decapping by the uridine tract, affinity purification with the U5 RNA revealed the presence of a decapping subcomplex at least consisting of hDcp2, Dcp1a, Edc4, LSm1, and LSm4 that were specifically bound to the U-5 RNA but not the U-0 RNA. In addition to promoting decapping, the U-tract stabilized the 3' end of the RNA by preventing 3' to 5' exonucleolytic decay to ensure 5' end directional degradation. These data suggest that following post-transcriptional oligo uridylation of an mRNA or mRNA fragment, the U-tract has the capacity to specifically stimulate 5' end decapping to expedite mRNA decay.
