Dataset Information

EIF1 modulates the recognition of sub-optimal translation start sites and steers gene expression control mediated by uORFs.

ABSTRACT: Alternative translation initiation mechanisms such as leaky scanning and re-initiation potentiate the polycistronic nature of transcripts. By allowing for reprogrammed translation, these mechanisms can mediate biological responses to stress stimuli. We combined proteomics with ribosome profiling and mRNA sequencing to identify the biological targets of translation control triggered by the eukaryotic translation initiation factor 1 (eIF1), a protein implicated in the stringency of start codon selection. We quantified expression changes of over 4,000 proteins and 10,000 actively translated transcripts, leading to the identification of 245 transcripts undergoing translational control mediated by upstream open reading frames (uORFs) upon eIF1 deprivation. The stringency of start codon selection and preference for an optimal nucleotide context were largely diminished leading to translational upregulation of uORFs with sub-optimal start sites. Affected genes were implicated in energy production and sensing of metabolic stress. Interestingly, knockdown of eIF1 elicited a synergic response from eIF5 and eIF1B.

OTHER RELATED OMICS DATASETS IN: PRJNA344393

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Leukocyte, Epithelial Cell, Colon

DISEASE(S): Colon Cancer,Acute Leukemia

SUBMITTER: Daria Gawron

LAB HEAD: Kris Gevaert

PROVIDER: PXD004980 | Pride | 2017-09-13

REPOSITORIES: Pride

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eIF1 modulates the recognition of suboptimal translation initiation sites and steers gene expression via uORFs.

Fijalkowska Daria D Verbruggen Steven S Ndah Elvis E Jonckheere Veronique V Menschaert Gerben G Van Damme Petra P

Nucleic acids research 20170701 13

Alternative translation initiation mechanisms such as leaky scanning and reinitiation potentiate the polycistronic nature of human transcripts. By allowing for reprogrammed translation, these mechanisms can mediate biological responses to stimuli. We combined proteomics with ribosome profiling and mRNA sequencing to identify the biological targets of translation control triggered by the eukaryotic translation initiation factor 1 (eIF1), a protein implicated in the stringency of start codon selec ...[more]

PMID: 28541577

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Project description:Translation of an mRNA in eukaryotes starts at AUG in most cases. Near-cognate codons (NCCs) such as UUG, ACG and AUU are also used as start sites at low levels in S. cerevisiae. Initiation from NCCs or AUGs in the 5’-untranslated regions (UTRs) of mRNAs can lead to translation of upstream open reading frames (uORFs) that might regulate expression of the main ORF (mORF). Although there is some circumstantial evidence that the translation of uORFs can be affected by environmental conditions, little is known about how it is affected by changes in growth temperature. Using reporter assays, we found that changes in growth temperature can affect translation from NCC start sites in yeast cells, suggesting the possibility that gene expression could be regulated by temperature by altering use of different uORF start codons. Using ribosome profiling, we provide evidence that growth temperature regulates the efficiency of translation of nearly 200 uORFs in S. cerevisiae. Of these uORFs, most that start with an AUG codon have increased translational efficiency at 37 ˚C relative to 30 ˚C and decreased efficiency at 20 ˚C. For translationally regulated uORFs starting with NCCs, we did not observe a general trend for the direction of regulation as a function of temperature, suggesting mRNA-specific features can determine the mode of temperature-dependent regulation. Consistent with this conclusion, the position of the uORFs in the 5’-leader relative to the 5’-cap and the start codon of the main ORF correlates with the direction of temperature-dependent regulation of uORF translation. We have identified several novel cases in which changes in uORF translation are inversely correlated with changes in the translational efficiency of the downstream main ORF. Our data suggest that translation of these mRNAs is subject to temperature-dependent, uORF-mediated regulation. Overall, our data suggest that alterations in the translation of specific uORFs by temperature can regulate gene expression in S. cerevisiae.

Project description:Microarray comparisons of polysome loading in wild-type Arabidopsis and eif3h mutant; Goal: ; To find the target mRNAs that are translationally regulated by eIF3h. BACKGROUND: The eukaryotic translation initiation factor eIF3 has multiple roles during the initiation of translation of cytoplasmic mRNAs. However, the contributions of individual subunits of eIF3 to the translation of specific mRNAs remain poorly understood. RESULTS: Working with stable reporter transgenes in Arabidopsis thaliana it was demonstrated that the h subunit of; eIF3 contributes to the efficient translation initiation of mRNAs harboring upstream open reading frames (uORFs) in their 5â leader sequence. uORFs, which can function as devices for translational regulation, are present in over 30% of Arabidopsis mRNAs, and are enriched among mRNAs for transcriptional regulators and protein modifying enzymes. Microarray comparisons of polysome loading in wild-type and eif3h mutant plants revealed that eIF3h generally helps to maintain efficient polysome loading of mRNAs harboring multiple uORFs. Independently, eIF3h also boosted polysome loading of mRNAs with long coding sequences. Moreover, the lesion in eIF3h revealed a concerted upregulation of translation for specific functional subgroups of mRNAs, including ribosomal proteins and proteins involved in photosynthesis. CONCLUSIONS: The intact eIF3h protein contributes to efficient translation initiation on 5â leader sequences harboring multiple uORFs, although mRNA features independent of uORFs were also implicated. Moreover, our data suggest that regulons of translational control can be revealed by mutations in generic translation initiation factors. Experiment Overall Design: Polysomal and non-polysomal RNA samples were isolated from 10-day-old wild-type and eif3h mutant plants. The translation state (ratio between the polysome and non-polysome, PL/NP) for each gene in the WT and in the mutant was separately established, and then the translation states between the genotype were compared.

Dataset Information

EIF1 modulates the recognition of sub-optimal translation start sites and steers gene expression control mediated by uORFs.

Publications

eIF1 modulates the recognition of suboptimal translation initiation sites and steers gene expression via uORFs.

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