Project description:Accurate annotations of protein coding regions are essential for understanding how genetic information is translated into biological functions. The recent development of ribosome footprint profiling provides an important new tool for measuring translation. Here we describe riboHMM, a new method that uses ribosome footprint data along with gene expression and sequence information to accurately infer translated sequences. We applied our method to human lymphoblastoid cell lines and identified 7,863 previously unannotated coding sequences, including 445 translated sequences in pseudogenes and 2,442 translated upstream open reading frames. We observed an enrichment of harringtonine-treated ribosome footprints at the inferred initiation sites, validating many of the novel coding sequences. In aggregate, the novel sequences exhibit significant signatures of purifying selection indicative of protein-coding function, suggesting that many of the novel sequences are functional. We observed that nearly 40% of bicistronic transcripts showed significant negative correlation in the levels of translation of their two coding sequences, suggesting a key regulatory role for these novel translated sequences. Despite evidence for their functional importance, the novel peptide sequences were detected by mass spectrometry at a lower rate than predicted based on data from annotated proteins, thus suggesting that many of the novel peptide products may be relatively short-lived. Our work illustrates the value of ribosome profiling for improving coding annotations, and significantly expands the set of known coding regions.
Project description:Ribosome profiling analyses showed thousands of translated open reading frames in a cell encoding noncanonical peptides. To examine their functional roles, we stably overexpressed two noncanonical peptides (uSLC35A4 and iPGRMC1) in MCF-7 cells. And then we performed RNA-seq to examine differential gene expression upon gene overexpression.
Project description:Ribosome profiling suggests that ribosomes occupy many regions of the transcriptome thought to be non-coding, including 5' UTRs and lncRNAs. Apparent ribosome footprints outside of protein-coding regions raise the possibility of artifacts unrelated to translation, particularly when they occupy multiple, overlapping open reading frames (ORFs). Here we show hallmarks of translation in these footprints: co-purification with the large ribosomal subunit, response to drugs targeting elongation, trinucleotide periodicity, and initiation at early AUGs. We develop a metric for distinguishing between 80S footprints and nonribosomal sources using footprint size distributions, which validates the vast majority of footprints outside of coding regions. We present evidence for polypeptide production beyond annotated genes, including induction of immune responses following human cytomegalovirus (HCMV) infection. Translation is pervasive on cytosolic transcripts outside of conserved reading frames, and direct detection of this expanded universe of translated products enables efforts to understand how cells manage and exploit its consequences. Ribosome profiling to verify that true ribosome footprints shift in response to different elongation inhibitors (CHX vs Emetine) and co-purify with an affinity-tagged large ribosomal subunit (bound vs input)
Project description:Ribosome-footprint profiling provides genome-wide snapshots of translation, but technical challenges can confound its analysis. Here, we use improved methods to obtain ribosome-footprint profiles and mRNA abundances that more faithfully reflect gene expression in Saccharomyces cerevisiae. Our results support proposals that both the beginning of coding regions and codons matching rare tRNAs are more slowly translated. They also indicate that emergent polypeptides with as few as three basic residues within a 10-residue window tend to slow translation. With the improved mRNA measurements, the variation attributable to translational control in exponentially growing yeast was less than previously reported, and most of this variation could be predicted with a simple model that considered mRNA abundance, upstream open reading frames, cap-proximal structure and nucleotide composition, and lengths of the coding and 5'-untranslated regions. Collectively, our results provide a framework for executing and interpreting ribosome-profiling studies and reveal key features of translational control in yeast. Ribosome-footprint profiling and RNA-seq (total RNA, poly(A) selected, RiboMinus treated, or Ribo-Zero treated) from log-phase S. cerevisiae. The study includes a reanalysis of the two Samples from GSE53313. The reanalyzed data is linked to the Series record.
Project description:Small open reading frames (smORFs) can have important regulatory roles and give rise to stable proteins, yet their discovery based on sequence-based predictions and proteomics has been challenging. Ribosome profiling (Ribo-seq) data can provide valuable experimental evidence of RNA translation. Stringent analysis of P-sites, representing 1.3 billion high-confidence ribosome locations, revealed 5308 uORFs, 1652 smORFs in lincRNAs and 807 dORFs that are translated in humans. We here provide a comprehensive database of Ribo-seq smORFs for a more complete understanding of the translated human genome.
Project description:Small open reading frames (smORFs) can have important regulatory roles and give rise to stable proteins, yet their discovery based on sequence-based predictions and proteomics has been challenging. Ribosome profiling (Ribo-seq) data can provide valuable experimental evidence of RNA translation. Stringent analysis of P-sites, representing 1.3 billion high-confidence ribosome locations, revealed 5308 uORFs, 1652 smORFs in lincRNAs and 807 dORFs that are translated in humans. We here provide a comprehensive database of Ribo-seq smORFs for a more complete understanding of the translated human genome.
Project description:Three translatomic approaches were applied to the foodborne pathogen Campylobacter jejuni to identify translated open reading frames, start codons, and stop codons and reveal novel small proteins
Project description:Ribosome profiling suggests that ribosomes occupy many regions of the transcriptome thought to be non-coding, including 5' UTRs and lncRNAs. Apparent ribosome footprints outside of protein-coding regions raise the possibility of artifacts unrelated to translation, particularly when they occupy multiple, overlapping open reading frames (ORFs). Here we show hallmarks of translation in these footprints: co-purification with the large ribosomal subunit, response to drugs targeting elongation, trinucleotide periodicity, and initiation at early AUGs. We develop a metric for distinguishing between 80S footprints and nonribosomal sources using footprint size distributions, which validates the vast majority of footprints outside of coding regions. We present evidence for polypeptide production beyond annotated genes, including induction of immune responses following human cytomegalovirus (HCMV) infection. Translation is pervasive on cytosolic transcripts outside of conserved reading frames, and direct detection of this expanded universe of translated products enables efforts to understand how cells manage and exploit its consequences.
Project description:Oxaliplatin (L-OHP) serves as a standard chemotherapy for colorectal cancer, while the drug resistance is still a considerable challenge. Dysregulation of lncRNA is involved in cancer and recent translatomics has found some alleged lncRNA actually contained small open reading frames and could encode short peptides. This ribosome footprint profiling (Ribo-seq) was a paired-end sequencing and aimed to investigate whether lncRNA could regulate oxaliplatin resistance in colorectal cancer by encoding short peptides.