Related Experiment Video
Updated: Oct 16, 2025
Monitoring eIF4F Assembly by Measuring eIF4E-eIF4G Interaction in Live Cells
Published on: May 1, 2020
Translational repression of NMD targets by GIGYF2 and EIF4E2
Boris Zinshteyn1,2, Niladri K Sinha1,2, Syed Usman Enam1,2
1Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
Abstract:
Translation of messenger RNAs (mRNAs) with premature termination codons produces truncated proteins with potentially deleterious effects. This is prevented by nonsense-mediated mRNA decay (NMD) of these mRNAs. NMD is triggered by ribosomes terminating upstream of a splice site marked by an exon-junction complex (EJC), but also acts on many mRNAs lacking a splice junction after their termination codon. We developed a genome-wide CRISPR flow cytometry screen to identify regulators of mRNAs with premature termination codons in K562 cells. This screen recovered essentially all core NMD factors and suggested a role for EJC factors in degradation of PTCs without downstream splicing. Among the strongest hits were the translational repressors GIGYF2 and EIF4E2. GIGYF2 and EIF4E2 mediate translational repression but not mRNA decay of a subset of NMD targets and interact with NMD factors genetically and physically. Our results suggest a model wherein recognition of a stop codon as premature can lead to its translational repression through GIGYF2 and EIF4E2.
Insights
Nonsense-mediated mRNA decay (NMD) prevents harmful truncated proteins. This study identifies GIGYF2 and EIF4E2 as key regulators, linking premature stop codon recognition to translational repression.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Premature termination codons (PTCs) in messenger RNAs (mRNAs) lead to truncated proteins, potentially causing harm.
- Nonsense-mediated mRNA decay (NMD) is a crucial cellular surveillance pathway that degrades mRNAs with PTCs, preventing the production of aberrant proteins.
- While NMD is often associated with splice sites marked by exon-junction complexes (EJCs), its mechanisms for mRNAs without downstream splicing remain less understood.
Purpose of the Study:
- To identify novel regulators of mRNA decay and translational control in response to premature termination codons.
- To elucidate the mechanisms by which cells recognize and process mRNAs containing PTCs, particularly those lacking downstream splicing.
- To investigate the roles of translational repressors in the NMD pathway.
Main Methods:
- A genome-wide CRISPR-Cas9 screening approach coupled with flow cytometry was employed in K562 cells to identify genes regulating mRNAs with PTCs.
- Genetic and physical interaction studies were conducted to validate the roles of candidate regulators.
- Functional assays were performed to assess the impact of identified factors on mRNA decay and translation.
Main Results:
- The CRISPR screen successfully identified known core NMD factors and implicated exon-junction complex (EJC) factors in the degradation of PTC-containing mRNAs lacking downstream splicing.
- The translational repressors GIGYF2 and EIF4E2 emerged as strong hits, indicating a significant role in regulating mRNAs with PTCs.
- GIGYF2 and EIF4E2 were found to mediate translational repression, but not mRNA decay, for a subset of NMD targets, and they interact with NMD factors both genetically and physically.
Conclusions:
- The findings suggest a model where the recognition of a stop codon as premature can trigger translational repression via GIGYF2 and EIF4E2.
- This study expands our understanding of NMD regulation, highlighting the involvement of translational repressors in managing mRNAs with PTCs, even in the absence of downstream splicing.
- The results provide new insights into the complex interplay between translation, mRNA decay, and cellular quality control mechanisms.
Related Concept Videos
01:52Eukaryotic Transcription Inhibitors
Eukaryotic transcription inhibitors usually contain two distinct domains, a...
01:29Translational Regulation
02:27Nonsense-mediated mRNA Decay
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...
01:23Regulation of Expression at Multiple Steps
01:42What is Gene Expression?
Gene expression is the process in which DNA directs the synthesis of functional products, that is, proteins. Cells can regulate gene expression at various stages. It allows organisms to generate different cell types and enables cells to adapt to internal and external factors.
Genetic Information Flows from DNA to RNA to Protein
A gene is a stretch of DNA that serves as the blueprint for functional RNAs and proteins. Since DNA is made up of nucleotides and proteins consist of amino...
02:24Regulation of Expression Occurs at Multiple Steps
Transcription results in the generation of precursor (pre-mRNA) that consists of both exons and introns, which needs further processing before being translated to a...