Short interfering RNA induced generation and translation of stable 5 ′ mRNA cleavage intermediates

Publication date: August 2016 Source:Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms, Volume 1859, Issue 8 Author(s): Richa Singhania, Sandra Pavey, Elizabeth Payne, Wenyi Gu, Jennifer Clancy, Luqman Jubair, Thomas Preiss, Nicholas Saunders, Nigel A.J. McMillan Sequence-specific degradation of homologous mRNA is the main mechanism by which short-interfering RNAs (siRNAs) suppress gene expression. Generally, it is assumed that the mRNA fragments resulting from Ago2 cleavage are rapidly degraded, thus making the transcript translation-incompetent. However, the molecular mechanisms involved in the post-cleavage mRNA decay are not completely understood and the fate of cleavage intermediates has been poorly studied. Using specific siRNAs and short-hairpin RNAs (shRNAs) we show that the 5′ and 3′ mRNA cleavage fragments of human papilloma virus type 16 (HPV-16) E6/7 mRNA, over-expressed in cervical malignancies, are unevenly degraded. Intriguingly, the 5′ mRNA fragment was more abundant and displayed a greater stability than the corresponding 3′ mRNA fragment in RNAi-treated cells. Further analysis revealed that the 5′ mRNA fragment was polysome-associated, indicating its active translation, and this was further confirmed by using tagged E7 protein to show that C-terminally truncated proteins were produced in treated cells. Overall, our findings provide new insight into the degradation of siRNA-targeted transcripts and show that RNAi can alter ...
Source: Biochimica et Biophysica Acta (BBA) Gene Regulatory Mechanisms - Category: Genetics & Stem Cells Source Type: research