GIGYF2 and 4EHP Inhibit Translation Initiation of Defective Messenger RNAs to Assist Ribosome-Associated Quality Control
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE153597 | GEO | 2020/07/01
REPOSITORIES: GEO
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Project description:Viral infection both activates stress signaling pathways and redistributes ribosomes away from host mRNAs to translate viral mRNAs. The intricacies of this ribosome shuffle from host to viral mRNAs are poorly understood Here, we uncover a role for the ribosome associated quality control (RQC) factor, ZNF598, during vaccinia virus mRNA translation. ZNF598 acts on collided ribosomes to ubiquitylate 40S subunit proteins uS10 and eS10 initiating RQC-dependent nascent chain degradation and ribosome recycling We show that vaccinia infection in human cells enhances uS10 ubiquitylation indicating an increased burden on RQC pathways during viral propagation. Consistent with an increased RQC demand, we demonstrate that vaccinia virus replication is impaired in cells which either lack ZNF598 or express a ubiquitylation deficient version of uS10 Using SILAC-based proteomics and concurrent RNAseq analysis, we determine that translation and not transcription of vaccinia virus mRNAs is compromised in cells with deficient RQC activity. Additionally, vaccinia virus infection reduces cellular RQC activity, suggesting that co-option of ZNF598 by vaccinia virus plays a critical role in translational reprogramming that is needed for optimal viral propagation.
2021-04-14 | GSE165732 | GEO
Project description:Translation of messenger RNAs (mRNAs) with premature translation 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.
2021-10-12 | PXD027487 | Pride
Project description:Translation of messenger RNAs (mRNAs) with premature translation 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.
2021-10-12 | PXD027479 | Pride
Project description:Ribosomes are highly abundant cellular machines that perform the essential task of translating the genetic code into proteins. Cellular translation activity is finely tuned and proteostasis insults, such as those incurred upon viral infection, activate stress signaling pathways that result in translation reprogramming. Viral infection selectively shuts down host mRNA while redistributing ribosomes for selective translation of viral mRNAs. The intricacies of this selective ribosome shuffle from host to viral mRNAs are poorly understood. Here, we uncover a role for the ribosome associated quality control (RQC) factor ZNF598, a sensor for collided ribosomes, as a critical factor for vaccinia virus mRNA translation. Collided ribosomes are sensed by ZNF598, which ubiquitylates 40S subunit proteins uS10 and eS10 and thereby initiates RQC-dependent nascent chain degradation and ribosome recycling. We show that vaccinia infection in human cells enhances uS10 ubiquitylation indicating an increased burden on RQC pathways during viral propagation. Consistent with an increased RQC demand, we demonstrate that vaccinia virus replication is impaired in cells which either lack ZNF598 or contain a ubiquitylation deficient version of uS10. Using SILAC-based proteomics and concurrent RNAseq analysis, we determine that host translation of vaccinia virus mRNAs is compromised in cells that lack RQC activity as compared to control cells whereas there was little evidence of differences in host or viral transcription. Additionally, vaccinia virus infection resulted in a loss of cellular RQC activity, suggesting that ribosomes engaged in viral protein production recruit ZNF598 away from its function in host translation. Thus, co-option of ZNF598 by vaccinia virus plays a critical role in translational reprogramming that is needed for optimal viral propagation.
2021-01-05 | MSV000086660 | MassIVE
Project description:Ribosome-associated quality control (RQC) represents a rescue pathway in eukaryotic cells triggered upon translational stalling. Collided ribosomes are recognized for subsequent dissociation followed by targeting of the faulty nascent peptides for degradation. However, endogenous RQC inducing sequences and the mechanism underlying the ubiquitin-dependent ribosome dissociation remain poorly understood. Here, we identified the SDD1 mRNA from S. cerevisiae as an endogenous RQC substrate and reveal its mRNA and nascent peptide dependent stalling mechanism by mutational and cryo-EM analyses. In vitro translation of SDD1 mRNA enabled the reconstitution of Hel2-dependent poly-ubiquitination of colliding di- and preferentially tri-ribosomes. Their distinct architecture is visualized by cryo-EM and provides the structural basis for more efficient recognition by Hel2 over disomes. Subsequently, the Slh1/Rqt2 helicase subunit of the RQC trigger (RQT) complex preferentially dissociates the first stalled poly-ubiquitinated ribosome in an ATP dependent manner. Together, these findings provide fundamental mechanistic insights into RQC and its physiological role in dealing with endogenous substrates to maintain cellular protein homeostasis.
2020-02-24 | PXD017196 | Pride
Project description:The control of mRNA stability plays a central role in regulating gene expression patterns. While much is known about the roles of 5´ and 3´ untranslated regions in the mRNA stability control, the impact of protein-coding sequences on mRNA stability had been obscure. Recently, several groups reported that codon composition in the ORF affects mRNA deadenylation and degradation rates in a translation-dependent manner. Hence, codons define not only the amino acid sequences to be synthesized but also the stability of mRNAs. However, how 61 codons differently affect mRNA stability remains unclear. Besides, aberrant stalling of the ribosome induces ribosome quality control (RQC) and No-go decay. The relationship between the two co-translational mRNA decay pathways is not systematically analyzed. To precisely characterize the effects of 61 codons on mRNA stability, we developed a simplified reporter system that allows detection of the effect of every single codon on mRNA stability in zebrafish embryos. Using this system, we show that the effect of codons on mRNA stability is partially but significantly correlated with the translation elongation rate and tRNA abundance. Interestingly, the codon effect is still maintained in zebrafish embryos lacking Znf598, an essential mediator of RQC and NGD. Znf598-dependent NGD targets a particular type of ribosome stalling but has limited impact on endogenous mRNA stability. Our study thus defines two related co-translational mRNA decay pathways during animal development.
2020-05-05 | GSE133392 | GEO
Project description:Translation of aberrant mRNAs can cause ribosomes to stall, leading to collisions with trailing ribosomes. Collided ribosomes are specifically recognized by ZNF598 to initiate protein and mRNA quality control pathways. Here we found using quantitative proteomics of collided ribosomes that EDF1 is a ZNF598-independent sensor of ribosome collisions. EDF1 recruits and stabilizes GIGYF2 at collisions to inhibit translation initiation in cis via 4EHP. The GIGYF2 axis acts independently of the ZNF598 axis, but each pathway’s output is more pronounced without the other. We propose that the widely conserved and highly abundant EDF1 monitors the transcriptome for excessive ribosome density, then triggers a GIGYF2-mediated response to locally and temporarily reduce ribosome loading. Only when collisions persist is translation abandoned to initiate ZNF598-dependent quality control. This tiered response to ribosome collisions would allow cells to dynamically tune translation rates while ensuring fidelity of the resulting protein products.
2020-07-14 | PXD020239 | Pride
Project description:The ribosome-associated protein quality control (RQC) system that resolves stalled translation events is activated when ribosomes collide and form disome, trisome or higher order complexes. However, it is unclear whether this system distinguishes collision complexes formed on defective mRNAs from those with functional roles on endogenous transcripts. Here, we performed disome and trisome footprint profiling in yeast and found collisions were enriched on diverse sequence motifs known to slow translation. When 60S recycling was inhibited, disomes accumulated at stop codons and could move into the 3’UTR to reinitiate translation. The ubiquitin ligase and RQC factor Hel2/ZNF598 generally recognized collisions but did not trigger degradation of endogenous transcripts. However, loss of Hel2 triggered the integrated stress response, via phosphorylation of eIF2alpha, thus linking these pathways. Our results suggest that Hel2 has a role in sensing ribosome collisions on endogenous mRNAs and such events may be important for cellular homeostasis.
2020-05-26 | GSE139036 | GEO
Project description:In the cell, stalled ribosomes are rescued through ribosome-associated protein quality-control (RQC) pathways. We demonstrate that RqcH is responsible for tRNAAla selection during RQC elongation, whereas RqcP lacks any tRNA specificity. The ribosomal protein uL11 is crucial for RqcH, but not RqcP, recruitment to the 50S subunit, and B. subtilis lacking uL11 are RQC-deficient. Through mutational mapping, we identify critical residues within RqcH and RqcP that are important for interaction with the P-site tRNA and/or the 50S subunit. Collectively, our findings provide mechanistic insight into the role of RqcH and RqcP in the bacterial RQC pathway. the synthesis of C-terminal poly-Alanine ‘tail’. While it is well-established that RqcP and RqcH are essential for poly-Alanine-tailing in living cells, here, by reconstituting the RQC elongation biochemically we provide a direct proof that the two factors are sufficient. We demonstrate that while RqcH is responsible for tRNAAla selection during RQC elongation, RqcP lacks the tRNA specificity. Through mutational mapping we show that stable interaction of RqcP with 23S rRNA – but not with tRNA – is crucial for RQC, supporting the role of the E-site bound RqcP as a pawl of RQC elongation ratchet. We show that ribosomal protein uL11 is crucial for RqcH – but nor RqcP – recruitment to 50S, and B. subtilis lacking uL11 is RQC-deficient. Finally, we show that proteins encoded by non-stop mRNAs are not universally efficiently targeted by RQC, and that simultaneous disruption of RQC and trans-translation results in bacterial filamentation
2021-08-19 | GSE174254 | GEO
Project description:GIGYF2 and 4EHP Inhibit Translation Initiation of Defective Messenger RNAs to Assist Ribosome-Associated Quality Control
| PRJNA643292 | ENA