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40S ribosome profiling reveals distinct roles for Tma20/Tma22 (MCT-1/DENR) and Tma64 (eIF2D) in 40S subunit recycling

ABSTRACT: 40S ribosome profiling reveals distinct roles for Tma20/Tma22 (MCT-1/DENR) and Tma64 (eIF2D) in 40S subunit recycling

PROVIDER: PRJNA608705 | ENA |

REPOSITORIES: ENA

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40S ribosome profiling reveals distinct roles for Tma20/Tma22 (MCT-1/DENR) and Tma64 (eIF2D) in 40S subunit recycling

Project description:The recycling of ribosomes at stop codons for use in further rounds of translation is critical for efficient protein synthesis. Removal of the 60S subunit is catalyzed by the ATPase Rli1 (ABCE1) while removal of the 40S is thought to require Tma64 (eIF2D), Tma20 (MCT-1), and Tma22 (DENR). However, it remains unclear how these Tma proteins cause 40S removal and control reinitiation of downstream translation. Here we developed an enhanced 40S ribosome footprinting strategy to directly observe intermediate steps of ribosome recycling in cells. Deletion of the genes encoding these Tma proteins resulted in broad accumulation of unrecycled 40S subunits at stop codons, directly establishing their role in 40S recycling. Furthermore, the Tma20/Tma22 heterodimer was responsible for a majority of 40S recycling events while Tma64 played a minor role. Introduction of an autism-associated mutation into TMA22 resulted in a loss of 40S recycling activity, linking ribosome recycling and neurological disease.

2021-03-01 | GSE145904 | GEO

Tma64 (eIF2D), Tma20 (MCT-1), and Tma22 (DENR) recycle post-termination 40S subunits in vivo

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

Hcr1/eIF3j is a 60S ribosomal subunit recycling accessory factor in vivo

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

Reprogramming of translation in yeast cells impaired for ribosome recycling favors short, efficiently translated mRNAs

Project description:Yeast strains lacking orthologs of mammalian eIF2D (Tma64), and either MCT-1 (Tma20) or DENR (Tma22) are broadly impaired for 40S recycling; however, it was unknown whether this defect leads to reduced 43S PIC levels with an impact on translation of particular mRNAs. To test this, we by combined ribosome footprint profiling with RNA-seq analysis of mRNA abundance.

2021-03-31 | GSE166987 | GEO

40S ribosome profiling reveals distinct roles for Tma20/Tma22 (MCT-1/DENR) and Tma64 (eIF2D) in 40S subunit recycling.

Project description: Not available

| S-EPMC8137927 | biostudies-literature

Tma64 (eIF2D), Tma20 (MCT-1), and Tma22 (DENR) recycle post-termination 40S subunits in vivo

Project description:Tma64 (eIF2D), Tma20 (MCT-1), and Tma22 (DENR) recycle post-termination 40S subunits in vivo

| PRJNA429210 | ENA

MCT-1 enhances translation

Project description:MCT-1 is an oncogene initially identified in a human T-cell lymphoma. Subsequently, MCT-1 protein levels were found to be elevated in a subset of diffuse large B-cell lymphoma. Forced expression of MCT-1 has recently been shown to induce cell proliferation as well as activate survival-related pathways protecting lymphoid cells from apoptosis. We document here that MCT-1 interacts with the density-regulated protein (DENR/DRP), containing the SUI1 translation initiation domain, found in many translation initiation factors. MCT-1 contains the PUA domain, a recently described RNA binding domain that is found in several tRNA and rRNA modification enzymes. Our findings established that MCT-1 protein is interacting with the cap complex through its PUA domain and enhances translation. Furtheremore, our data support a putative role for the MCT-1 oncogene in translation and suggests a mechanism for its role in lymphomagenesis. Keywords: Gene upregulation by MCT-1

2006-09-15 | GSE4805 | GEO

Master stress response gene ATF4 & other oncogenes are translated by DENR-dependent reinitiation

Project description:Translation efficiency varies 1000-fold between different mRNAs, thereby strongly impacting protein expression. Translation of the master stress response gene ATF4 increases in response to stress, but the molecular mechanisms are not well understood. We discover here that translation initiation factors DENR, MCTS1 and eIF2D are absolutely required to induce ATF4 translation upon stress, by promoting translation reinitiation on the ATF4 5’UTR. Hence DENR and MCTS1 are important players in the cellular Integrated Stress Response. We find DENR and MCTS1 promote reinitiation after long uORFs with specific penultimate codons, due to the tRNA that remains attached to 40S ribosomes after translation termination. This provides a model for how DENR and MCTS1 promote translation reinitiation. Since cancer cells are exposed to many stresses, they require ATF4 for survival and proliferation. We find a strong correlation between DENR•MCTS1 expression and ATF4 activity across cancers. Additional oncogenes including a-Raf, c-Raf and Cdk4 have long uORFs and are translated in a DENR•MCTS1 dependent manner. This explains in part why DENR and MCTS1 are oncogenes.

2020-07-18 | GSE140084 | GEO

Polysomes from DENR knockdown cells

Project description:The aim was to identify transcripts that are poorly translated upon knockdown of DENR. Lysates from control (GFP) and DENR knockdown S2 cells were run on polysome gradients. RNA from the (80S peak + polysome peaks) was isolated and analyzed by microarrays. In parallel, total RNA from the cells was also profiled as a normalization control and profiled. The 'translation score' of translated mRNA to total RNA was then calculated for control and DENR knockdown cells. Two biological replicates for DENR knockdown and GFP knockdown were performed. For each sample, (80S+polysomes) and total RNA were profiled, leading to 8 samples in total.

2014-06-30 | E-GEOD-54625 | biostudies-arrayexpress

Tma64/eIF2D, Tma20/MCT-1, and Tma22/DENR Recycle Post-termination 40S Subunits In Vivo.

Project description: Not available

| S-EPMC6225905 | biostudies-literature