Study reveals widespread stop codon readthrough as major regulatory mechanism in fruit flies
Researchers systematically characterized stop codon readthrough (SCR) in Drosophila melanogaster, identifying approximately 1,400 genes where ribosomes continue translating past the stop codon. Using ribosome profiling, comparative genomics, proteomics, and functional screening, they found both constitutive and tissue-restricted forms of SCR and identified conserved sequence elements that can trigger the process even in mammalian cells. The findings reframe SCR not as a rare translational error but as a pervasive regulatory mechanism in insects with potential implications for understanding gene expression more broadly.
A new preprint on bioRxiv reports a comprehensive characterization of stop codon readthrough (SCR) in the fruit fly Drosophila melanogaster, catalogued in a resource called the Drosophila Stop Codon Readthrough Atlas. The study identified roughly 1,400 SCR genes by integrating multiple high-throughput approaches, including ribosome profiling, comparative genomics, proteomics, and functional screening. The researchers distinguished between constitutive SCR—occurring in all tissues—and tissue-restricted SCR, and pinpointed conserved cis-regulatory elements sufficient to stimulate the process. Notably, many of these elements retained functionality when tested in mammalian cells, suggesting the underlying molecular machinery is broadly conserved. Contrary to expectations, the key difference between insect and mammalian SCR was not the efficiency of translation termination itself, but rather the responsiveness of insect cells to SCR-promoting regulatory elements. The study also found that SCR was associated with increased overall protein output, implying a functional role beyond simply diversifying the proteome. These results establish SCR as a major, previously underappreciated layer of gene regulation in insects.
What's missing
As a preprint, this study has not yet undergone formal peer review, so findings should be interpreted with caution. The authors do not fully resolve the downstream functional consequences of the ~1,400 identified SCR events—it remains unclear for most genes what biological roles the readthrough protein extensions serve. The mechanism by which insect cells are specifically responsive to SCR-promoting elements, but mammalian cells are not, is described but not fully explained at a molecular level. Additionally, whether the tissue-restricted SCR patterns are driven by tissue-specific trans-acting factors remains an open question.
What different sources said
- bioRxivCenter
Regulatory landscape of widespread stop codon readthrough in Drosophila
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