Ribosomal protein S7 ubiquitination during ER stress in yeast is associated with selective mRNA translation and stress outcome.
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ABSTRACT:
ORGANISM(S): Saccharomyces cerevisiae
PROVIDER: GSE128578 | GEO | 2020/11/12
REPOSITORIES: GEO
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Project description:The ribosome is a translational apparatus that comprises about 80 ribosomal proteins and four rRNAs. Recent studies reported that ubiquitination of the ribosomal proteins plays a pivotal role in translational control and ribosome-associated quality control (RQC). However, little is known about the dynamics of ribosome ubiquitination under complex biological processes of multicellular organisms. To study ribosome ubiquitination during animal development, we generated a zebrafish strain that expresses a FLAG-tagged ribosomal protein Rpl36/eL36 from its endogenous locus. Combining affinity purification of ribosomes from rpl36-FLAG zebrafish embryos with immunoblotting analysis, we analyzed ribosome ubiquitination during zebrafish development. Our data showed that ubiquitination of ribosomal proteins dynamically changed as development proceeded. We further revealed that Znf598, an E3 ubiquitin ligase that triggers RQC, contributed to the ribosome ubiquitination during zebrafish development. LC-MS/MS analysis and immunoblotting analysis identified lysines 139 of ribosomal protein Rps10/eS10 as pivotal ubiquitination sites on the ribosome during development. Finally, we demonstrated that an Rps10 K139/140R mutation reduced overall ribosome ubiquitination pattern. Collectively, these results reveal dynamics and complexity of ribosome ubiquitination in zebrafish development.
2023-10-11 | PXD039560 | JPOST Repository
Project description:Disruptions of protein homeostasis in the endoplasmic reticulum (ER) elicit activation of the unfolded protein response (UPR), a translation- and transcription-coupled proteostatic stress response pathway. The primary translational control arm of the UPR is initiated by the PERK-dependent phosphorylation of eIF2α, leading to a large-scale reprogramming of translation and subsequent activation of an ATF4-mediated transcriptional program. It has remained challenging, however, to accurately evaluate the contribution of each component of the eIF2α/ATF4 pathway to the remodelling of transcription and translation. Here, we have used mouse embryonic fibroblasts containing either a knock-in of the non-phosphorylatable eIF2α S51A mutant or knock-out for ATF4 by ribosome profiling and mRNA-seq to define the specific contributions of eIF2α phosphoryation and ATF4 in controlling the translational and transcriptional components of the UPR. These studies show that the transcriptional and translational targets of each P-eIF2α, ATF4, and the other UPR gene expression programs overlapped extensively, leading to a core set of UPR genes whose robust expression in response to ER stress is driven by multiple mechanisms. The identification of other, more factor-specific targets illustrated the potential for functional specialization of the UPR. As the UPR progressed temporally, cells employed distinct combinations of transcriptional and translational mechanisms, initiated by different factors, to adapt to ongoing stress. These effects were accompanied by a buffering effect where changes in mRNA levels were coupled to opposing changes in ribosome loading, a property which makes cooperation between transcription and translation essential to confer robust protein expression. Translational analysis by ribosome profiling and mRNA-seq of PERK pathways mutants during the UPR. Mouse embryonic fibroblasts (MEFs) lacking components of the PERK pathway (eIF2a phosphorylation and ATF4) were subjected to ER stress and analyzed by ribosome profiling.
2016-07-03 | E-GEOD-68265 | biostudies-arrayexpress
Project description:Sse1, yeast cytosolic Hsp110 chaperone, is a wellknown Nucleotide Exchange Factor (NEF), a protein-disaggregase and a Chaperone linked to Protein Synthesis (CLIPS). Here we demonstrate SSE1’s genetic interaction with IRE1 and HAC1, the Endoplasmic Reticulum-Unfolded Protein Response (ER-UPR) sensors. sse1Δ strain exhibits an ER-UPR signalling-dependent resistance to tunicamycin-induced ER stress. Importantly, ER-stress-responsive reorganization of translating ribosomes from polysomes to monosomes is inefficient in SSE1 deleted strain leading to uninterrupted protein translation and starkly different ER-UPR kinetics. sse1Δ exhibits faster ER-UPR induction and quicker reversal to basal state compared to wildtype (WT) cells. Interestingly, ER-stress mediated yeast cell division arrest is escaped in sse1Δ strain during long term tunicamycin stress indicating important role of this chaperone in controlling cell division during ER stress. Furthermore, sse1Δ strain shows significantly higher cell viability in comparison to WT yeast, following short-term as well as long-term tunicamycin stress. In summary, we show that cytosolic chaperone Sse1 genetically interacts with ER-UPR pathway, controls the kinetics of ER-UPR, stress-induced cell division arrest and cell viability during global ER stress by tunicamycin.
2024-04-19 | PXD045382 | Pride
Project description:The accumulation of unfolded proteins in the lumen of the endoplasmic reticulum (ER) causes stress and induces the unfolded protein response (UPR) which is characterised in part by the transcriptional induction of genes involved in assisting protein folding. Translational responses to ER stress have been less well described and here we report on a genome-wide analysis of translational regulation in the response to the ER stress-inducing agent dithiothreitol (DTT) in Saccharomyces cerevisiae. Although the observed polysome profiles were similar under control and ER stress conditions microarray analysis identified transcipt-specific translational regulation. Genes with functions in ribosomal biogenesis and assembly were translationally repressed under ER stress. In contrast mRNAs for known UPR genes, including the UPR transcription factor HAC1, the ER-oxidoreductase ERO1 and the ER-associated protein degradation (ERAD) gene DER1 were enriched in polysomal fractions under ER stress conditions. In addition, we show that splicing of HAC1 mRNA is required for efficient ribosomal loading and that Gcn2p is required for normal HAC1 splicing, so shedding light on the role of this protein kinase in the UPR pathway. Experiment Overall Design: Polyribosomes were extracted from S. cerevisiae cells treated with 2 mM DTT or water (control), and fractionated according to ribosome loading. Following RNA purification from these fractions, for each sub-polysomal and polysomal RNA sample, fractions from three independent extracts per treatment (DTT/control) were pooled.
2008-06-11 | E-GEOD-10091 | biostudies-arrayexpress
Project description:Accumulation of misfolded proteins in the endoplasmic reticulum (ER) triggers the unfolded protein response (UPR), which results in the increased phosphorylation of the eukaryotic initiation factor, eIF2a, and widespread translational repression. Protein synthesis is subsequently restored following the stress-induced transcriptional upregulation of GADD34 (growth arrest and DNA damage transcript 34) protein, a regulator of an eIF2a phosphatase. Genome-wide ribosome foot-printing in WT and GADD34-/- MEFs established that GADD34 mRNA is translated in unstressed cells and identified numerous mRNAs, whose translation was dependent on GADD34 even in the absence of ER stress. Following UPR activation, temporal analyses showed that the translational profile in GADD34-/- MEFs was stalled, displaying a pattern that mirrors the early response to UPR in WT MEFs. Basal GADD34 expression is also required for de-repression of translation and displacement of ER-bound polysomes that occur in early UPR. Thus, the overall UPR response is delayed in the GADD34-/- MEFs, gradually recovering as CReP expression increased. These studies reveal a critical role for basal GADD34 in the propagation of UPR signals in MEFs and mice and suggest that delayed UPR signaling protects GADD34-/- mice from tunicamycin-induced renal toxicity.
2015-10-01 | GSE69800 | GEO
Project description:Translation elongation rates are regulated to ensure proper conformation and biological function of proteins. Translation of either non-stop mRNA or transcripts coding for poly-basic sequences induces ribosome stalling, and the arrest product is degraded by the ribosome-mediated quality control system (RQC). During this process, the stalled ribosome is dissociated into subunits, and the polypeptide is ubiquitinated by the E3 ubiquitin ligase Listerin on the 60S large ribosomal subunit (LSU) leading to subsequent proteasomal degradation. However, it is largely unknown how stalled ribosomes are recognized and dissociated into subunits. Here we report that ubiquitination of the ribosomal protein uS10 by the E3 ubiquitin ligase Hel2 is required for the production of the RQC substrate. RQC-trigger (RQT) factors, a RNA helicase-family protein Slh1/Rqt2, ubiquitin binding protein Cue3/Rqt3 and yKR023W/Rqt4, were also required for the primary steps of RQC, and associated with Hel2-ribosome complexes. Rqt2-4 factors were dispensable for the ubiquitination of uS10 by Hel2/Rqt1 and associated with ribosomes independent of the ubiquitination of uS10. However, the ubiquitin-binding activity of Rqt3 were crucial to trigger RQC. Cryo-electron microscopy (cryo-EM) analysis revealed that Hel2 bound ribosomes are in an rotated state containing hybrid state AP- and PE-tRNAs. Furthermore, ribosome profiling revealed that short footprints, hallmarks of hybrid state ribosomes18, were accumulated at tandem CGA rare codons at the beginning of the poly arginine stalling sequence and long footprints at subsequent codons, respectively. Short footprints at CGA codons were decreased in rqt1 mutant but drastically increased in uS10 mutants defective in the ubiquitination or rqt2 mutant. Collectively, our results demonstrate that Hel2 stabilizes ratcheted ribosomes leading to ubiquitination of uS10. Subsequently, Rqt2-4 factors target these hybrid state ribosomes specifically, allowing subsequent RQC reactions.
2017-07-31 | GSE79622 | GEO
Project description:Translation elongation stalling has the potential to produce toxic truncated protein fragments. Translation of either non-stop mRNA or transcripts coding for poly-basic sequences induces ribosome stalling, and the arrest product is degraded by the ribosome-mediated quality control (RQC) system. During this process, the stalled ribosome is dissociated into subunits, and the polypeptide is ubiquitinated by the E3 ubiquitin ligase Listerin on the 60S large ribosomal subunit, leading to subsequent proteasomal degradation. However, it is largely unknown how the specific stalled ribosomes are recognized as aberrant to engage the RQC system. Here, we report that ubiquitination of the ribosomal protein uS10 of the 40S small ribosomal subunit, by the E3 ubiquitin ligase Hel2 (or RQC-trigger (Rqt) 1) initiates RQC. We identified a novel RQC-trigger (RQT) complex composed of the RNA helicase-family protein Slh1/Rqt2, the ubiquitin binding protein Cue3/Rqt3, and yKR023W/Rqt4 that is required for RQC. The defects in RQC of the RQT mutants correlated with sensitivity to anisomycin, which stalls ribosome at the rotated form, suggesting that RQT factors rescue ribosomes stalled by this drug. Our un-biased survey by ribosome profiling revealed that ribosomes stalled at the rotated state with specific pairs of codons at P-A sites serve as RQC substrates. Rqt1 specifically ubiquitinates these arrested ribosomes to target them to the RQT complex, allowing subsequent RQC reactions including dissociation of the stalled ribosome into subunits. Our results provide mechanistic insight into the surveillance system for aberrant proteins induced by ribosome stalling and mediated by ribosome ubiquitination.
2017-07-31 | GSE90919 | GEO
Project description:Ribosome-associated quality control pathways respond to defects in translational elongation to recycle arrested ribosomes and degrade aberrant polypeptides and mRNAs. Loss of an individual tRNA gene leads to ribosomal pausing that is resolved by the translational GTPase GTPBP2, and in its absence causes neuron death. Here we show that loss of the homologous protein GTPBP1 during tRNA deficiency in the mouse brain also leads to codon-specific ribosome pausing and neurodegeneration, suggesting that these non-redundant translational GTPases function in the same pathway to mitigate ribosome pausing. Ribosome stalling in the mutant brain led to activation of the integrated stress response (ISR) mediated by GCN2 and decreased mTORC1 signaling. However, in contrast to the ISR, which enhanced neuron survival, reduced mTORC1 signaling increased neuronal death. Our data demonstrate that GTPBP1 functions as an important quality control mechanism during translation elongation and suggest that translational signaling pathways intricately interact to regulate neuronal homeostasis during defective translation elongation.
2020-10-26 | GSE157902 | GEO
Project description:Ubiquitination has crucial roles in many cellular processes and dysregulation of ubiquitin machinery enzymes can result in various forms of pathogenesis. Cells only have a limited set of E2 ubiquitin-conjugating enzymes to support the ubiquitination of many cellular targets. As individual E2 enzymes have many different substrates and interactions between E2 enzymes and their substrates can be transient, it is challenging to define all in vivo substrates of an individual E2 and the cellular processes it affects. Particularly challenging in this respect is UBE2D3, a very promiscuous E2 enzyme that affects a broad range of processes. Here, we set out to identify in vivo targets of UBE2D3 by using SILAC-based quantitative ubiquitin diGly proteomics to study global proteome and ubiquitinome changes associated with UBE2D3 depletion. UBE2D3 depletion changed the global proteome, with proteins from metabolic pathways, in particular retinol metabolism, being the most affected. However, the impact of UBE2D3 depletion on the ubiquitinome was much more prominent and, interestingly, identified pathways related to mRNA translation as top pathways being affected. Indeed, we find that ubiquitination of the ribosomal proteins RPS10 and RPS20, critical for ribosome-associated protein quality control (RQC), is dependent on UBE2D3. Moreover, we find that UBE2D3 limits monoubiquitination of histone H2B at lysine 120, mediated by the E3 ligase RNF20. This identifies UBE2D3 as a potential regulator of the diverse and critical cellular processes that are controlled by H2B monoubiquitination. Collectively, our findings show that depletion of an E2 ubiquitin-conjugating enzyme in combination with quantitative diGly-based ubiquitinome profiling is a powerful tool to identify new in vivo E2 substrates, as we have done here for UBE2D3. Together with our identification of RQC factors and H2B as novel in vivo targets of UBE2D3, our work provides an important resource for further studies on the in vivo functions of UBE2D3.
2023-04-12 | PXD026054 | Pride
Project description:The life cycle of the ribosome is highly regulated by ubiquitination and deubiquitination events that are remarkably well conserved across the evolutionary scale. We uncover the role of the ovarian tumor (OTU)-class deubiquitinase OTUD6 in setting the level of protein translation by deubiquitination of the RPS7/eS7 subunit of the 40S ribosome in vivo in Drosophila, using endogenously tagged wild-type and mutant proteins. Coimmunoprecipitation and enrichment of monoubiquitinated proteins from catalytically inactive OTUD6 flies revealed the 40S ribosomal protein RPS7 as the major OTUD6 ribosomal substrate. OTUD6 genetically interacts with the 40S protein RACK1 and the ubiquitin E3 ligases CNOT4 and RNF10 to set alkylation stress sensitivity by regulating the level of RPS7 monoubiquitination. OTUD6 specifically interacts with RPS7 on the free 40S subunit, and not on translation initiation complexes or the 80S translating ribosome. Moreover, mRNAs are depleted of free 40S ribosomal subunits in catalytically inactive OTUD6 flies. OTUD6 bidirectionally promotes the global level of protein translation through its action on RPS7. OTUD6 protein is itself regulated by different physiological conditions and stressors to lower the level of RPS7 monoubiquitination and increase the level of protein translation. We propose that OTUD6 promotes translation initiation, the rate limiting step in protein translation, by titering the availability of 40S subunits for forming the 43S preinitiation complex.
2023-01-10 | MSV000091040 | MassIVE