scholarly journals Conserved Upstream Open Reading Frame Nascent Peptides That Control Translation

2020 ◽  
Vol 54 (1) ◽  
pp. 237-264
Author(s):  
Thomas E. Dever ◽  
Ivaylo P. Ivanov ◽  
Matthew S. Sachs
Keyword(s):  
Gene Expression ◽  
Open Reading Frames ◽  
Upstream Open Reading Frame ◽  
Messenger Rnas ◽  
Regulate Gene Expression ◽  
Reading Frame ◽  
Ribosome Stalling ◽  
Evolutionarily Conserved ◽  
Upstream Open Reading Frames ◽  
Control Translation

Cells utilize transcriptional and posttranscriptional mechanisms to alter gene expression in response to environmental cues. Gene-specific controls, including changing the translation of specific messenger RNAs (mRNAs), provide a rapid means to respond precisely to different conditions. Upstream open reading frames (uORFs) are known to control the translation of mRNAs. Recent studies in bacteria and eukaryotes have revealed the functions of evolutionarily conserved uORF-encoded peptides. Some of these uORF-encoded nascent peptides enable responses to specific metabolites to modulate the translation of their mRNAs by stalling ribosomes and through ribosome stalling may also modulate the level of their mRNAs. In this review, we highlight several examples of conserved uORF nascent peptides that stall ribosomes to regulate gene expression in response to specific metabolites in bacteria, fungi, mammals, and plants.

scholarly journals A First Step towards Learning which uORFs Regulate Gene Expression

2006 ◽  
Vol 3 (2) ◽  
pp. 109-122 ◽  
Author(s):  
◽  
Christopher H. Bryant ◽  
Graham J.L. Kemp ◽  
Marija Cvijovic
Keyword(s):  
Gene Expression ◽  
Inductive Logic ◽  
Preliminary Evidence ◽  
Open Reading Frames ◽  
Yeast Saccharomyces Cerevisiae ◽  
Regulate Gene Expression ◽  
Integrative System ◽  
Upstream Open Reading Frames ◽  
Reading Frames ◽  
Regulate Gene

Summary We have taken a first step towards learning which upstream Open Reading Frames (uORFs) regulate gene expression (i.e., which uORFs are functional) in the yeast Saccharomyces cerevisiae. We do this by integrating data from several resources and combining a bioinformatics tool, ORF Finder, with a machine learning technique, inductive logic programming (ILP). Here, we report the challenge of using ILP as part of this integrative system, in order to automatically generate a model that identifies functional uORFs. Our method makes searching for novel functional uORFs more efficient than random sampling. An attempt has been made to predict novel functional uORFs using our method. Some preliminary evidence that our model may be biologically meaningful is presented.

scholarly journals Autonomous functionality of an upstream open reading frame in polycistronic mammalian mRNAs

2018 ◽  
Author(s):  
Shohei Kitano ◽  
Gabriel Pratt ◽  
Keizo Takao ◽  
Yasunori Aizawa
Keyword(s):  
Brain Regions ◽  
Ribosome Profiling ◽  
Open Reading Frames ◽  
Upstream Open Reading Frame ◽  
Translation Regulation ◽  
Reading Frame ◽  
Eukaryotic Translation ◽  
Upstream Open Reading Frames ◽  
Human And Mouse ◽  
Reading Frames

SUMMARYUpstream open reading frames (uORFs) are established as cis-acting elements for eukaryotic translation of annotated ORFs (anORFs) located on the same mRNAs. Here, we identified a mammalian uORF with functions that are independent from anORF translation regulation. Bioinformatics screening using ribosome profiling data of human and mouse brains yielded 308 neurologically vital genes from which anORF and uORFs are polycistronically translated in both species. Among them, Arhgef9 contains a uORF named SPICA, which is highly conserved among vertebrates and stably translated only in specific brain regions of mice. Disruption of SPICA translation by ATG-to-TAG substitutions did not perturb translation or function of its anORF product, collybistin. SPICA-null mice displayed abnormal maternal reproductive performance and enhanced anxiety-like behavior, characteristic of ARHGEF9-associated neurological disorders. This study demonstrates that mammalian uORFs can be independent genetic units, revising the prevailing dogma of the monocistronic gene in mammals, and even eukaryotes.

scholarly journals Translation Initiation from Conserved Non-AUG Codons Provides Additional Layers of Regulation and Coding Capacity

mBio ◽  
2017 ◽  
Vol 8 (3) ◽  
Author(s):  
Ivaylo P. Ivanov ◽  
Jiajie Wei ◽  
Stephen Z. Caster ◽  
Kristina M. Smith ◽  
Audrey M. Michel ◽  
...  
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Neurospora Crassa ◽  
Open Reading Frames ◽  
Reading Frame ◽  
Coding Sequence ◽  
Cell Extracts ◽  
Upstream Open Reading Frames ◽  
Reading Frames

ABSTRACT Neurospora crassa cpc-1 and Saccharomyces cerevisiae GCN4 are homologs specifying transcription activators that drive the transcriptional response to amino acid limitation. The cpc-1 mRNA contains two upstream open reading frames (uORFs) in its >700-nucleotide (nt) 5′ leader, and its expression is controlled at the level of translation in response to amino acid starvation. We used N. crassa cell extracts and obtained data indicating that cpc-1 uORF1 and uORF2 are functionally analogous to GCN4 uORF1 and uORF4, respectively, in controlling translation. We also found that the 5′ region upstream of the main coding sequence of the cpc-1 mRNA extends for more than 700 nucleotides without any in-frame stop codon. For 100 cpc-1 homologs from Pezizomycotina and from selected Basidiomycota, 5′ conserved extensions of the CPC1 reading frame are also observed. Multiple non-AUG near-cognate codons (NCCs) in the CPC1 reading frame upstream of uORF2, some deeply conserved, could potentially initiate translation. At least four NCCs initiated translation in vitro . In vivo data were consistent with initiation at NCCs to produce N-terminally extended N. crassa CPC1 isoforms. The pivotal role played by CPC1, combined with its translational regulation by uORFs and NCC utilization, underscores the emerging significance of noncanonical initiation events in controlling gene expression. IMPORTANCE There is a deepening and widening appreciation of the diverse roles of translation in controlling gene expression. A central fungal transcription factor, the best-studied example of which is Saccharomyces cerevisiae GCN4, is crucial for the response to amino acid limitation. Two upstream open reading frames (uORFs) in the GCN4 mRNA are critical for controlling GCN4 synthesis. We observed that two uORFs in the corresponding Neurospora crassa cpc-1 mRNA appear functionally analogous to the GCN4 uORFs. We also discovered that, surprisingly, unlike GCN4, the CPC1 coding sequence extends far upstream from the presumed AUG start codon with no other in-frame AUG codons. Similar extensions were seen in homologs from many filamentous fungi. We observed that multiple non-AUG near-cognate codons (NCCs) in this extended reading frame, some conserved, initiated translation to produce longer forms of CPC1, underscoring the significance of noncanonical initiation in controlling gene expression.

scholarly journals Messenger RNAs with large numbers of upstream open reading frames are translated via leaky scanning and reinitiation in the asexual stages of Plasmodium falciparum

Parasitology ◽  
2020 ◽  
Vol 147 (10) ◽  
pp. 1100-1113
Author(s):  
Chhaminder Kaur ◽  
Mayank Kumar ◽  
Swati Patankar
Keyword(s):  
Plasmodium Falciparum ◽  
Open Reading Frames ◽  
Luciferase Reporter ◽  
Messenger Rnas ◽  
Leaky Scanning ◽  
Luciferase Reporter Gene ◽  
Reading Frame ◽  
Genome Data ◽  
Upstream Open Reading Frames ◽  
Reading Frames

AbstractThe genome of Plasmodium falciparum has one of the most skewed base-pair compositions of any eukaryote, with an AT content of 80–90%. As start and stop codons are AT-rich, the probability of finding upstream open reading frames (uORFs) in messenger RNAs (mRNAs) is high and parasite mRNAs have an average of 11 uORFs in their leader sequences. Similar to other eukaryotes, uORFs repress the translation of the downstream open reading frame (dORF) in P. falciparum, yet the parasite translation machinery is able to bypass these uORFs and reach the dORF to initiate translation. This can happen by leaky scanning and/or reinitiation.In this report, we assessed leaky scanning and reinitiation by studying the effect of uORFs on the translation of a dORF, in this case, the luciferase reporter gene, and showed that both mechanisms are employed in the asexual blood stages of P. falciparum. Furthermore, in addition to the codon usage of the uORF, translation of the dORF is governed by the Kozak sequence and length of the uORF, and inter-cistronic distance between the uORF and dORF. Based on these features whole-genome data was analysed to uncover classes of genes that might be regulated by uORFs. This study indicates that leaky scanning and reinitiation appear to be widespread in asexual stages of P. falciparum, which may require modifications of existing factors that are involved in translation initiation in addition to novel, parasite-specific proteins.

scholarly journals Temperature-Dependent Regulation of Upstream Open Reading Frame Translation inS. Cerevisiae

2019 ◽  
Author(s):  
Shardul D. Kulkarni ◽  
Fujun Zhou ◽  
Neelam Dabas Sen ◽  
Hongen Zhang ◽  
Alan G. Hinnebusch ◽  
...  
Keyword(s):  
Gene Expression ◽  
Growth Temperature ◽  
Ribosome Profiling ◽  
Open Reading Frames ◽  
Yeast Cells ◽  
Upstream Open Reading Frame ◽  
Start Codon ◽  
Translational Efficiency ◽  
Temperature Dependent ◽  
Reading Frame

AbstractBackgroundTranslation 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 inS. 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.ResultsUsing 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 inS. 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.ConclusionsOverall, our data suggest that alterations in the translation of specific uORFs by temperature can regulate gene expression inS. cerevisiae.

scholarly journals Genome-wide identification of Arabidopsis non-AUG-initiated upstream ORFs with evolutionarily conserved regulatory sequences that control protein expression levels

2021 ◽  
Author(s):  
Yuta Hiragori ◽  
Hiro Takahashi ◽  
Noriya Hayashi ◽  
Shun Sasaki ◽  
Kodai Nakao ◽  
...  
Keyword(s):  
Regulatory Peptides ◽  
Inhibitory Effect ◽  
Ribosome Profiling ◽  
Open Reading Frames ◽  
Regulatory Sequences ◽  
Dependent Manner ◽  
Protein Coding ◽  
Genome Wide ◽  
Evolutionarily Conserved ◽  
Upstream Open Reading Frames

Upstream open reading frames (uORFs) are short ORFs found in the 5′-UTRs of many eukaryotic transcripts and can influence the translation of protein-coding main ORFs (mORFs). Recent genome-wide ribosome profiling studies have revealed that thousands of uORFs initiate translation at non-AUG start codons. However, the physiological significance of these non-AUG uORFs has so far been demonstrated for only a few of them. It is conceivable that physiologically important non-AUG uORFs are evolutionarily conserved across species. In this study, using a combination of bioinformatics and experimental approaches, we searched the Arabidopsis genome for non-AUG-initiated uORFs with conserved sequences that control the expression of the mORF-encoded proteins. As a result, we identified four novel regulatory non-AUG uORFs. Among these, two exerted repressive effects on mORF expression in an amino acid sequence-dependent manner. These two non-AUG uORFs are likely to encode regulatory peptides that cause ribosome stalling, thereby enhancing their repressive effects. In contrast, one of the identified regulatory non-AUG uORFs promoted mORF expression by alleviating the inhibitory effect of a downstream AUG-initiated uORF. These findings provide insights into the mechanisms that enable non-AUG uORFs to play regulatory roles despite their low translation initiation efficiencies.

scholarly journals The Transcription Factor Xrp1 is Required for PERK-Mediated Antioxidant Gene Induction in Drosophila

2021 ◽  
Author(s):  
Brian Brown ◽  
Sahana Mitra ◽  
Finnegan D Roach ◽  
Deepika Vasudevan ◽  
Hyung Don Ryoo
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Upstream Open Reading Frame ◽  
Bzip Transcription Factor ◽  
Specific Gene ◽  
Antioxidant Genes ◽  
Reading Frame ◽  
Protein Levels ◽  
Signaling Axis ◽  
The Unfolded Protein Response

PERK is an endoplasmic reticulum (ER) transmembrane sensor that phosphorylates eIF2a to initiate the Unfolded Protein Response (UPR). eIF2a phosphorylation promotes stress-responsive gene expression most notably through the transcription factor ATF4 that contains a regulatory 5′ leader. Possible PERK effectors other than ATF4 remain poorly understood. Here, we report that the bZIP transcription factor Xrp1 is required for ATF4-independent PERK signaling. Cell type-specific gene expression profiling in Drosophila indicated that delta-family glutathione-S-transferases (gstD) are prominently induced by the UPR-activating transgene Rh1G69D. Perk was necessary and sufficient for such gstD induction, but ATF4 was not required. Instead, Perk and other regulators of eIF2a phosphorylation regulated Xrp1 protein levels to induce gstDs. The Xrp1 5′ leader has a conserved upstream Open Reading Frame (uORF) analogous to those that regulate ATF4 translation. The gstD-GFP reporter induction required putative Xrp1 binding sites. These results indicate that antioxidant genes are highly induced by a previously unrecognized UPR signaling axis consisting of PERK and Xrp1.

scholarly journals uORF-Tools – Workflow for the determination of translation-regulatory upstream open reading frames

2018 ◽  
Author(s):  
Anica Scholz ◽  
Florian Eggenhofer ◽  
Rick Gelhausen ◽  
Björn Grüning ◽  
Kathi Zarnack ◽  
...  
Keyword(s):  
Ribosome Profiling ◽  
Open Reading Frames ◽  
Annotation File ◽  
Inhibitory Effects ◽  
Protein Coding ◽  
Reading Frame ◽  
Upstream Open Reading Frames ◽  
Induced Changes ◽  
Reading Frames

AbstractRibosome 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 identifies 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.

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