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Translation reinitiation after uORFs does not fully protect mRNAs from nonsense-mediated decay
Paul J Russell1,2,3,4, Jacob A Slivka3,5, Elaina P Boyle3,4
1Cellular, Molecular, and Biochemical Sciences Program, The Ohio State University, Columbus, Ohio 43210, USA.
RNA (New York, N.Y.)
|March 6, 2023
Summary
Upstream open reading frames (uORFs) can influence mRNA stability. This study shows that while translation reinitiation after uORFs is possible, it does not effectively prevent nonsense-mediated decay (NMD) in mammalian cells.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Nearly 50% of mammalian transcripts feature upstream open reading frames (uORFs).
- uORFs are typically small and can inhibit translation or facilitate reinitiation.
- uORF termination can trigger nonsense-mediated mRNA decay (NMD).
Purpose of the Study:
- To investigate the influence of uORF length on translation reinitiation.
- To determine the impact of uORF translation reinitiation on mRNA stability.
- To assess the role of reinitiation in preventing NMD.
Main Methods:
- Constructed custom 5' UTRs and uORF sequences in HeLa cells.
- Measured reporter mRNA half-lives.
- Analyzed available mRNA half-life datasets for uORF length correlations.
Main Results:
- Translation reinitiation occurs on heterologous sequences and favors smaller uORFs.
- Reinitiation is enhanced by increased initiation factors.
- uORF length and reinitiation did not robustly prevent NMD, as mRNA half-lives were not significantly prolonged.
Conclusions:
- Translation reinitiation after uORFs is not a reliable mechanism for preventing NMD in mammalian cells.
- The decision to initiate NMD appears to occur prior to ribosome reinitiation after uORF translation.
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