Upstream Open Reading Frames Differentially Regulate Gene-specific Translation in the Integrated Stress Response.
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ABSTRACT:
SUBMITTER: Young SK
PROVIDER: S-EPMC5016099 | biostudies-other | 2016 Aug
REPOSITORIES: biostudies-other
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Project description:For protein synthesis that occurs locally in dendrites, the translational control mechanisms are much more important for neuronal functioning than the transcription levels. Here, we show that uORFs (upstream open reading frames) in the 5' untranslated region (5'UTR) play a critical role in regulation of the translation of protein kinase M? (PKM?). Elimination of these uORFs activates translation of the reporter protein in vitro and in primary cultures of rat hippocampal neurons. Using cell-free translation systems, we demonstrate that translational initiation complexes are formed only on uORFs. Further, we address the mechanism of translational repression of PKM? translation, by uORFs. We observed an increase in translation of the reporter protein under the control of PKM? leader in neuronal culture during non-specific activation by picrotoxin. We also show that such a mechanism is similar to the mechanism seen in cell stress, as application of sodium arsenite to neuron cultures induced translation of mRNA carrying PKM? 5'UTR similarly to picrotoxin activation. Therefore, we suppose that phosphorylation of eIF2a, like in cell stress, is a main regulator of PKM? translation. Altogether, our findings considerably extend our understanding of the role of uORF in regulation of PKM? translation in activated neurons, important at early stages of LTP.
| S-EPMC5061749 | biostudies-literature
Project description:Upstream open reading frames (uORFs) initiate translation within mRNA 5’ leaders,and have the potential to altermain coding sequence(CDS) translationontranscripts in which they reside. Ribosome profiling(RP)studies suggest that translating ribosomes are pervasive within 5’ leadersacross model systems. However, the significance of this observationremains unclear. To explore a role for uORF usage in neuronal differentiation, we performed RP on undifferentiated and differentiated human neuroblastoma cells. Using a spectral coherence algorithm (SPECtre),we identify4,954uORFsacross31%of all neuroblastoma transcripts. These uORFspredominantly utilize non-AUG initiationcodonsand exhibit translational efficiencies(TE)comparable to annotated coding regions. Usage of both AUG initiated uORFs and aconservedandconsistently translated subset of non-AUG initiated uORFs correlateswith repressed CDS translation. Ribosomal protein transcripts are enriched in uORFs, and select uORFs on such transcripts were validated for expression. Withneuronal differentiation, we observedan overall positive correlation between translational shifts in uORF/CDSpairs. However,a subset of transcripts exhibit inverse shifts in translation of uORF/CDSpairs. TheseuORFsare enriched in AUG initiation sites, non-overlapping, and shorterin length. Cumulatively, CDSs downstream of uORFs characterized by persistent translation show smaller shifts in TE withneuronal differentiation relative to CDSs without a predicted uORF, suggesting that fluctuations in CDS translation are buffered by uORF translation. In sum, this work provides insights into the dynamic relationshipsand potential regulatory functionsof uORF/CDS pairs in a model of neuronal differentiation.
2018-09-07 | GSE119615 | GEO
Project description:BackgroundUpstream open reading frames (uORFs) initiate translation within mRNA 5' leaders, and have the potential to alter main coding sequence (CDS) translation on transcripts in which they reside. Ribosome profiling (RP) studies suggest that translating ribosomes are pervasive within 5' leaders across model systems. However, the significance of this observation remains unclear. To explore a role for uORF usage in a model of neuronal differentiation, we performed RP on undifferentiated and differentiated human neuroblastoma cells.ResultsUsing a spectral coherence algorithm (SPECtre), we identify 4954 consistently translated uORFs across 31% of all neuroblastoma transcripts. These uORFs predominantly utilize non-AUG initiation codons and exhibit translational efficiencies (TE) comparable to annotated coding regions. On a population basis, the global impact of both AUG and non-AUG initiated uORFs on basal CDS translation were small, even when analysis is limited to conserved and consistently translated uORFs. However, uORFs did alter the translation of a subset of genes, including the Diamond-Blackfan Anemia associated ribosomal gene RPS24. With retinoic acid induced differentiation, we observed an overall positive correlation in translational shifts between uORF/CDS pairs. However, CDSs downstream of uORFs show smaller shifts in TE with differentiation relative to CDSs without a predicted uORF, suggesting that uORF translation buffers cell state dependent fluctuations in CDS translation.ConclusionThis work provides insights into the dynamic relationships and potential regulatory functions of uORF/CDS pairs in a model of neuronal differentiation.
| S-EPMC6528255 | biostudies-literature
Project description:The Kaposi's sarcoma-associated herpesvirus (KSHV) protein kinase, encoded by ORF36, functions to phosphorylate cellular and viral targets important in the KSHV lifecycle and to activate the anti-viral prodrug ganciclovir. Unlike the vast majority of mapped KSHV genes, no viral transcript has been identified with ORF36 positioned as the 5'-proximal gene. Here we report that ORF36 is robustly translated as a downstream cistron from the ORF35-37 polycistronic transcript in a cap-dependent manner. We identified two short, upstream open reading frames (uORFs) within the 5' UTR of the polycistronic mRNA. While both uORFs function as negative regulators of ORF35, unexpectedly, the second allows for the translation of the downstream ORF36 gene by a termination-reinitiation mechanism. Positional conservation of uORFs within a number of related viruses suggests that this may be a common ?-herpesviral adaptation of a host translational regulatory mechanism.
| S-EPMC3561293 | biostudies-literature
Project description:Ribosome profiling (ribo-seq) provides a means to analyze active translation by determining ribosome occupancy in a transcriptome-wide manner. The vast majority of ribosome protected fragments (RPFs) resides within the protein-coding sequence of mRNAs. However, commonly reads are also found within the transcript leader sequence (TLS) (aka 5' untranslated region) preceding the main open reading frame (ORF), indicating the translation of regulatory upstream ORFs (uORFs). Here, we present a workflow for the identification of translation-regulatory uORFs. Specifically, uORF-Tools uses Ribo-TISH to identify uORFs within a given dataset and generates a uORF annotation file. In addition, a comprehensive human uORF annotation file, based on 35 ribo-seq files, is provided, which can serve as an alternative input file for the workflow. To assess the translation-regulatory activity of the uORFs, stimulus-induced changes in the ratio of the RPFs residing in the main ORFs relative to those found in the associated uORFs are determined. The resulting output file allows for the easy identification of candidate uORFs, which have translation-inhibitory effects on their associated main ORFs. uORF-Tools is available as a free and open Snakemake workflow at https://github.com/Biochemistry1-FFM/uORF-Tools. It is easily installed and all necessary tools are provided in a version-controlled manner, which also ensures lasting usability. uORF-Tools is designed for intuitive use and requires only limited computing times and resources.
| S-EPMC6742470 | biostudies-literature
Project description:BACKGROUND: Upstream open reading frames (uORFs) can down-regulate the translation of the main open reading frame (mORF) through two broad mechanisms: ribosomal stalling and reducing reinitiation efficiency. In distantly related plants, such as rice and Arabidopsis, it has been found that conserved uORFs are rare in these transcriptomes with approximately 100 loci. It is unclear how prevalent conserved uORFs are in closely related plants. RESULTS: We used a homology-based approach to identify conserved uORFs in five cereals (monocots) that could potentially regulate translation. Our approach used a modified reciprocal best hit method to identify putative orthologous sequences that were then analysed by a comparative R-nomics program called uORFSCAN to find conserved uORFs. CONCLUSION: This research identified new genes that may be controlled at the level of translation by conserved uORFs. We report that conserved uORFs are rare (<150 loci contain them) in cereal transcriptomes, are generally short (less than 100 nt), highly conserved (50% median amino acid sequence similarity), position independent in their 5'-UTRs, and their start codon context and the usage of rare codons for translation does not appear to be important.
| S-EPMC2527020 | biostudies-literature
Project description:To find novel short coding sequences from accumulated full-length cDNA sequences, proteomic analysis of small proteins expressed in human leukemia K562 cells was performed using high-resolution nanoflow liquid chromatography coupled with electrospray ionization tandem mass spectrometry. Our analysis led to the identification of 54 proteins not more than 100 amino acids in length, including four novel ones. These novel short coding sequences were all located upstream of the longest open reading frame (ORF) of the corresponding cDNA. Our findings indicate that the translation of short ORFs occurs in vivo whether or not there exists a longer coding region in the downstream of the mRNA. This investigation provides the first direct evidence of translation of upstream ORFs in human cells, which could greatly change the current outline of the human proteome.
| S-EPMC528919 | biostudies-literature
Project description:Ribosome profiling has revealed pervasive but largely uncharacterized translation outside of canonical coding sequences (CDSs). Here, we exploit a systematic CRISPR-based screening strategy to identify hundreds of non-canonical CDSs that are essential for cellular growth and whose disruption elicit specific, robust transcriptomic and phenotypic changes in human cells. Functional characterization of the encoded microproteins reveals distinct cellular localizations, specific protein binding partners, and hundreds that are presented by the HLA system. Interestingly, we find multiple microproteins encoded in upstream open reading frames, which form stable complexes with the main, canonical protein encoded on the same mRNA, thus revealing the diverse use of functional bicistronic operons in mammals. Together, our results point to a family of functional human microproteins that play critical and diverse cellular roles.
2020-03-14 | GSE131650 | GEO
Project description:Upstream open reading frames (uORFs) represent translational control elements within eukaryotic transcript leader sequences. Recent data showed that uORFs can encode for biologically active proteins and human leucocyte antigen (HLA)-presented peptides and suggest their potential role in cancer cell development and survival. However, it is so far unclear if uORF-encoded peptides could serve as tumor-associated antigen targets and thus also play a role in cancer immune surveillance. Combining mass spectrometry-based immunopeptidome analysis in primary tumor and healthy tissues and evaluation of proto-oncogene-associated uORF-mediated translational control we here identified a panel of HLA-presented tumor-associated uORF-derived antigens. These uORF-derived tumor antigens were further shown to induce multifunctional antigen-specific T cells, validating their suitability as antigen targets for T cell-based cancer immunotherapy. Our data further unravel the role of uORF-encoded peptides in malignant disease, suggesting uORF-derived tumor-associated antigens as targets for anti-cancer immune surveillance and immunotherapy development.
2022-04-04 | PXD025716 | Pride
Project description:BackgroundSome upstream open reading frames (uORFs) regulate gene expression (i.e., they are functional) and can play key roles in keeping organisms healthy. However, how uORFs are involved in gene regulation is not yet fully understood. In order to get a complete view of how uORFs are involved in gene regulation, it is expected that a large number of experimentally verified functional uORFs are needed. Unfortunately, wet-experiments to verify that uORFs are functional are expensive.ResultsIn this paper, a new computational approach to predicting functional uORFs in the yeast Saccharomyces cerevisiae is presented. Our approach is based on inductive logic programming and makes use of a novel combination of knowledge about biological conservation, Gene Ontology annotations and genes' responses to different conditions. Our method results in a set of simple and informative hypotheses with an estimated sensitivity of 76%. The hypotheses predict 301 further genes to have 398 novel functional uORFs. Three (RPC11, TPK1, and FOL1) of these 301 genes have been hypothesised, following wet-experiments, by a related study to have functional uORFs. A comparison with another related study suggests that eleven of the predicted functional uORFs from genes LDB17, HEM3, CIN8, BCK2, PMC1, FAS1, APP1, ACC1, CKA2, SUR1, and ATH1 are strong candidates for wet-lab experimental studies.ConclusionsLearning based prediction of functional uORFs can be done with a high sensitivity. The predictions made in this study can serve as a list of candidates for subsequent wet-lab verification and might help to elucidate the regulatory roles of uORFs.
| S-EPMC2813248 | biostudies-literature