EIF3 associates with 80S ribosomes to promote translation elongation, mitochondrial homeostasis, and muscle health
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens Saccharomyces cerevisiae
PROVIDER: GSE149697 | GEO | 2020/06/15
REPOSITORIES: GEO
Similar Datasets
Project description:eIF3 is a multi-subunit complex thought to execute numerous functions in canonical translation initiation, including mRNA recruitment to the 40S ribosome, scanning for the start codon, and inhibition of 60S subunit joining 1–3. eIF3 was also found to interact with 40S and 60S ribosomal proteins and translation elongation factors 4, but a direct involvement in translation elongation has never been demonstrated. Using selective ribosome profiling, we made the unexpected observation that eIF3 remains bound to post-initiation 80S ribosomes, followed by release after translation of ~50 codons. Furthermore, eIF3 deficiency reduces early ribosomal elongation speed, particularly on mRNAs encoding proteins associated with membrane-associated functions, resulting in defective synthesis of their encoded proteins and abnormal mitochondrial and lysosomal physiology. Accordingly, heterozygous eIF3e+/- knockout mice accumulate giant mitochondria in skeletal muscle and show a progressive decline in muscle strength with age. Hence, in addition to its canonical role in translation initiation, eIF3 interacts with 80S ribosomes to enhance, at the level of early elongation, the synthesis of proteins with membrane-associated functions, an activity that is critical for normal muscle health.
2020-06-01 | GSE131074 | GEO
Project description:The recycling of ribosomal subunits after translation termination is critical for efficient gene expression. Tma64 (eIF2D), Tma20 (MCT-1), and Tma22 (DENR) function as 40S recycling factors in vitro, but it is unknown whether they perform this function in vivo or serve as alternative initiation factors. Ribosome profiling of strains missing these factors revealed 80S ribosomes queued behind the stop codon, consistent with a block in 40S recycling. We found that unrecycled ribosomes could reinitiate translation at AUG codons in the 3’UTR, as evidenced by peaks in the footprint data and 3’UTR reporter analysis. In vitro translation experiments using reporter mRNAs containing upstream ORFs (uORFs) further established that reinitiation increased in the absence of these proteins. In some cases, 40S ribosomes appeared to rejoin with 60S subunits and undergo an alternative 80S reinitiation process in 3’UTRs. These results support a crucial role for Tma64, Tma20, and Tma22 in the recycling of 40S ribosomal subunits at stop codons and translation reinitiation.
2018-08-30 | GSE108942 | GEO
Project description:Hcr1/eIF3j is a sub-stoichiometric subunit of eukaryotic initiation factor 3 (eIF3) that can dissociate the post-termination 40S ribosomal subunit from mRNA in vitro. We examined this ribosome recycling role in vivo by ribosome profiling and reporter assays and found that loss of Hcr1 led to reinitiation of translation in 3’UTRs, consistent with a defect in recycling. However, the defect appeared to be in recycling of the 60S subunit, rather than the 40S subunit, because reinitiation did not require an AUG codon and was suppressed by overexpression of the 60S dissociation factor Rli1/ABCE1. Consistent with a 60S recycling role, overexpression of Hcr1 could not compensate for loss of 40S recycling factors Tma64/eIF2D and Tma20/MCT-1. Intriguingly, loss of Hcr1 triggered higher expression of RLI1 via an apparent feedback loop. These findings suggest Hcr1/eIF3j is recruited to ribosomes at stop codons and may coordinate the transition to a new round of translation.
2019-05-23 | GSE124204 | GEO
Project description:eIF3 associates with 80S ribosomes to promote translation elongation, mitochondrial homeostasis, and muscle health
| PRJNA629777 | ENA
Project description:Firczuk2013 - Eukaryotic mRNA translation machinery
This is a model of Saccharomyces cerevisiae
mRNA translation which includes the initiation, elongation and termination phases. The model is for 20 condon mRNAs. The building of a multi-factor complex in initiation and also the different processes in elongation and termination are modelled in detail. The model takes into account that ribosomes cover more than one codon of mRNA so that the movement of ribosomes are effectively blocked by other ribosomes several codons downstream. It is assumed that 15 codons are occupied by each ribosome. This blocking effect is considered in reaction R18 in initiation and also reaction R26, the reaction where translocation of ribosomes takes place in elongation. The kinetic functions of these two reactions are based on MacDonald et al. 1968 and Heinrich & Rapaport 1980. All other kinetic functions follow mass-action kinetics. The concentrations of transfer RNA species (Met-tRNA, aa-tRNA and tRNA in the model) are kept constant, while the other species' concentrations can change in the course of the simulation. The model describes the translation of a short mRNA with 20 codons. Therefore, all reactions in the elongation cycle (R22, R23, R25, R26, R28 and R29) and the corresponding species are replicated accordingly to model the species with ribosomes bound at different positions. In summary, the model contains 165 different species and 141 reactions.
The value of the 56 rate constant parameters were estimated by fitting the model against a series of experimental data consisting of modulation of the various translation factors (Figures 2, 3 and S3). Overall the parameter estimation was carried out over 212 different data points (steady states).
This model is described in the article:
An in vivo control map for the eukaryotic mRNA translation machinery
Helena Firczuk, Shichina Kannambath, Jürgen Pahle, Amy Claydon, Robert Beynon, John Duncan, Hans Westerhoff, Pedro Mendes and John EG McCarthy
Molecular Systems Biology. 9:635
Abstract:
Rate control analysis defines the in vivo control map governing yeast protein synthesis and generates an extensively parameterized digital model of the translation pathway. Among other non-intuitive outcomes, translation demonstrates a high degree of functional modularity and comprises a non-stoichiometric combination of proteins manifesting functional convergence on a shared maximal translation rate. In exponentially growing cells, polypeptide elongation (eEF1A, eEF2, and eEF3) exerts the strongest control. The two other strong control points are recruitment of mRNA and tRNAi to the 40S ribosomal subunit (eIF4F and eIF2) and termination (eRF1; Dbp5). In contrast, factors that are found to promote mRNA scanning efficiency on a longer than-average 5′untranslated region (eIF1, eIF1A, Ded1, eIF2B, eIF3, and eIF5) exceed the levels required for maximal control. This is expected to allow the cell to minimize scanning transition times, particularly for longer 5′UTRs. The analysis reveals these and other collective adaptations of control shared across the factors, as well as features that reflect functional modularity and system robustness. Remarkably, gene duplication is implicated in the fine control of cellular protein synthesis.
This model is hosted on BioModels Database
and identified by: BIOMD0000000457
.
To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource
for published quantitative kinetic models
.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to the public
domain worldwide. Please refer to CC0 Public Domain
Dedication
for more information.
2024-09-02 | BIOMD0000000457 | BioModels
Project description:Translation regulation occurs largely during initiation. Currently, translation initiation can be studied in vitro, but these systems lack features present in vivo and on endogenous mRNAs. Here we develop selective 40S footprinting for visualizing initiating 40S ribosomes on endogenous mRNAs in vivo. It pinpoints where on an mRNA initiation factors join the ribosome to act, and where they leave. We discover that in human cells most scanning ribosomes remain attached to the 5’ cap. Consequently, only one ribosome scans a 5’UTR at a time, and 5’UTR length affects translation efficiency. We discover that eIF3B, eIF4G1 and eIF4E remain on translating 80S ribosomes with a decay half-length of ~12 codons. Hence ribosomes retain these initiation factors while translating short upstream Open Reading Frames (uORFs), providing an explanation for how ribosomes can re-initiate translation after uORFs in humans. This method will be of use for studying translation initiation mechanisms in vivo.
2020-06-25 | GSE139391 | GEO
Project description:Recent studies have revealed that the mRNA translation is punctuated by ribosomal pauses through the body of transcripts. However, little is known about its physiological significance and regulatory aspects. Here we present a multi-dimensional ribosome profiling approach to quantify the dynamics of initiation and elongation of 80S ribosomes across the entire transcriptome in mammalian cells. We show that a subset of transcripts have a significant pausing of 80S ribosome around the start codon, creating a major barrier to the commitment of translation elongation. Intriguingly, genes encoding ribosome proteins themselves exhibit an exceptionally high initiation pausing on their transcripts. Our studies also reveal that the initiation pausing is dependent on the 5’ untranslated region (5’ UTR) of mRNAs and subject to the regulation of mammalian target of rapamycin complex 1 (mTORC1). Thus, the initiation pausing of 80S ribosome represents a novel regulatory step in translational control mediated by nutrient signaling pathway. Untreated TSC2 WT MEFs, TSC2 KO MEFs and TSC2 WT MEFs, TSC2 KO MEFs treated with 20nM rapamycin for 30 minutes or 3hours were harvested for ribosme profiling. The fraction samples were pooled into three groups based on velocity sedimentation: single ribosome fraction (Small group), fractions with 2 ~ 4 ribosomes (Medium group), and the one with ≥5 ribosomes (Large group). RNA were extracted from the whole cell lysis and each fraction group.
2011-11-12 | E-GEOD-25331 | biostudies-arrayexpress
Project description:Recent studies have revealed that the mRNA translation is punctuated by ribosomal pauses through the body of transcripts. However, little is known about its physiological significance and regulatory aspects. Here we present a multi-dimensional ribosome profiling approach to quantify the dynamics of initiation and elongation of 80S ribosomes across the entire transcriptome in mammalian cells. We show that a subset of transcripts have a significant pausing of 80S ribosome around the start codon, creating a major barrier to the commitment of translation elongation. Intriguingly, genes encoding ribosome proteins themselves exhibit an exceptionally high initiation pausing on their transcripts. Our studies also reveal that the initiation pausing is dependent on the 5M-bM-^@M-^Y untranslated region (5M-bM-^@M-^Y UTR) of mRNAs and subject to the regulation of mammalian target of rapamycin complex 1 (mTORC1). Thus, the initiation pausing of 80S ribosome represents a novel regulatory step in translational control mediated by nutrient signaling pathway. Monitor the translational status of transcriptome in mammalian cells under different conditions
2011-11-12 | E-GEOD-25626 | biostudies-arrayexpress
Project description:We use mRNA-seq in combination with polysome profiling to determine translational status for all mRNAs in Drosophila mature oocytes and activated eggs. Puromycin-treated lysates are used as a negative control in polysome profiling experiments. Additionally, we use ribosome footprinting to globally measure translational efficiency of mRNAs in wild type mature oocytes as well as wild type and png mutant activated eggs. Lysates of hand-dissected Drosophila mature oocytes (containing ~540 M-NM-<g of total RNA) were subjected to separation by velocity sedimentation through sucrose gradients. In this way, free mRNAs (present in RNPs fraction) or those comigrating with ribosomal subunits (40S or 60S+80S fractions) or with varying numbers of bound ribosomes (low polysomes (2-4 ribosomes), medium polysomes (5-9 ribosomes), and heavy polysomes (more than 10 ribosomes) can be separated based on their size and collected as sucrose gradient fractions. To compare quantitatively the levels of every mRNA across the polysome gradient fractions, we added 5ng of S. cerevisiae mRNA as an exogenous spike-in to each of the six fractions of interest: RNPs, 40S, 60S+80S, low polysomes, medium polysomes and heavy polysomes. RNA was extraced from these fractions, follwing proteinase K treatment, by hot acid phenol method. In case of unfractionated lysates, RNA was extracted using TRIzol (Invitrogen) according to manufacturerM-bM-^@M-^Ys instructions. mRNA-seq samples were prepared from 1 M-NM-<g of total RNA (in case of sucrose gradient fractions and unfractionated lysates) and subject to Illumina based sequencing. Puromycin-treated lysates of mature oocytes or 0-2h Drosophila activated eggs (containing ~540 M-NM-<g of total RNA) were also subjected to separation by velocity sedimentation through sucrose gradients. Puromycin causes premature termination of elongating ribosomes and thus it can be used to determine whether the mRNAs co-sedimenting with the polysomal peaks (defined here as M-bM-^IM-%5 ribosomes) were actively engaged in translation. As an independent approach to assess translation and obtain information on the position of ribosomes on mRNAs, we employed ribosome footprinting. In addition to analyzing the same samples, as by polysome profiling, we also analyzed png mutant activated eggs by ribosome footprinting. Ribosome footprint profiling measures the number of ribosome-protected fragments (RPFs) derived from the mRNAs of each gene, resulting in a singular value of translational efficiency (TE) for each gene (TE=RPF/RNA).
2014-06-12 | E-GEOD-52799 | biostudies-arrayexpress
Project description:The REIL proteins are required for late ribosomal biogenesis and accumulation of the 60S large ribosome subunit in mature leaves of Arabidopsis thaliana upon acclimation to low temperature. To validate these functions in roots, we conducted a multi-level system analysis targeted at understanding defects and compensations responses of reil mutants before acclimation to low temperature and following temperature shift. Hydroponic root tissue enabled analysis of eukaryotic ribosome complexes with negligible interference of organelle ribosomes. Hydroponic cultivation attenuated the growth defect of reil mutants at low temperature and provided new insights into the primary functions of Arabidopsis REIL proteins. Arabidopsis tightly controls the balance of non-translating 40S and 60S subunits. Reil mutants initially deplete both non-translating subunits upon shift to 10°C and subsequently replenish these pools slowly. Reil mutations compensate the 60S biosynthesis defect by increased baseline levels of non-translating 40S and 60S subunits and depletion of a likely non-translating, KCl-sensitive 80S sub-fraction in the cold. We infer that Arabidopsis buffers fluctuating translation demands following temperature cues by activating non-translating ribosome fractions before de novo synthesis meets temperature-induced demands. Reil1 reil2 double mutants accumulate 43S-preinitiation complexes and pre-60S-maturation complexes and affect the paralog composition of non-translating ribosome fractions. With few exceptions, e.g. RPL3B and RPL24C, these changes were not under transcriptional control. Our study suggests requirement of de novo synthesis of eukaryotic ribosomes for long-term cold acclimation. Double mutant analysis indicates feedback control of REIL-mediated 60S maturation on NUC2 and eIF3C2 transcription and implies functions of two so far non-described proteins in late plant ribosome biogenesis. We propose that Arabidopsis requires biosynthesis of specialized ribosomes for successful cold acclimation.
2021-02-03 | GSE144916 | GEO