Dataset Information

SL-quant: a fast and flexible pipeline to quantify spliced leader trans-splicing events from RNA-seq data.

ABSTRACT: Background:The spliceosomal transfer of a short spliced leader (SL) RNA to an independent pre-mRNA molecule is called SL trans-splicing and is widespread in the nematode Caenorhabditis elegans. While RNA-sequencing (RNA-seq) data contain information on such events, properly documented methods to extract them are lacking. Findings:To address this, we developed SL-quant, a fast and flexible pipeline that adapts to paired-end and single-end RNA-seq data and accurately quantifies SL trans-splicing events. It is designed to work downstream of read mapping and uses the reads left unmapped as primary input. Briefly, the SL sequences are identified with high specificity and are trimmed from the input reads, which are then remapped on the reference genome and quantified at the nucleotide position level (SL trans-splice sites) or at the gene level. Conclusions:SL-quant completes within 10 minutes on a basic desktop computer for typical C. elegans RNA-seq datasets and can be applied to other species as well. Validating the method, the SL trans-splice sites identified display the expected consensus sequence, and the results of the gene-level quantification are predictive of the gene position within operons. We also compared SL-quant to a recently published SL-containing read identification strategy that was found to be more sensitive but less specific than SL-quant. Both methods are implemented as a bash script available under the MIT license [1]. Full instructions for its installation, usage, and adaptation to other organisms are provided.

SUBMITTER: Yague-Sanz C

PROVIDER: S-EPMC6055573 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

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SL-quant: a fast and flexible pipeline to quantify spliced leader trans-splicing events from RNA-seq data.

Yague-Sanz Carlo C Hermand Damien D

GigaScience 20180701 7

<h4>Background</h4>The spliceosomal transfer of a short spliced leader (SL) RNA to an independent pre-mRNA molecule is called SL trans-splicing and is widespread in the nematode Caenorhabditis elegans. While RNA-sequencing (RNA-seq) data contain information on such events, properly documented methods to extract them are lacking.<h4>Findings</h4>To address this, we developed SL-quant, a fast and flexible pipeline that adapts to paired-end and single-end RNA-seq data and accurately quantifies SL t ...[more]

PMID: 30010768

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Project description:BackgroundSpliced leader (SL) trans-splicing replaces the 5' end of pre-mRNAs with the spliced leader, an exon derived from a specialised non-coding RNA originating from elsewhere in the genome. This process is essential for resolving polycistronic pre-mRNAs produced by eukaryotic operons into monocistronic transcripts. SL trans-splicing and operons may have independently evolved multiple times throughout Eukarya, yet our understanding of these phenomena is limited to only a few well-characterised organisms, most notably C. elegans and trypanosomes. The primary barrier to systematic discovery and characterisation of SL trans-splicing and operons is the lack of computational tools for exploiting the surge of transcriptomic and genomic resources for a wide range of eukaryotes.ResultsHere we present two novel pipelines that automate the discovery of SLs and the prediction of operons in eukaryotic genomes from RNA-Seq data. SLIDR assembles putative SLs from 5' read tails present after read alignment to a reference genome or transcriptome, which are then verified by interrogating corresponding SL RNA genes for sequence motifs expected in bona fide SL RNA molecules. SLOPPR identifies RNA-Seq reads that contain a given 5' SL sequence, quantifies genome-wide SL trans-splicing events and predicts operons via distinct patterns of SL trans-splicing events across adjacent genes. We tested both pipelines with organisms known to carry out SL trans-splicing and organise their genes into operons, and demonstrate that (1) SLIDR correctly detects expected SLs and often discovers novel SL variants; (2) SLOPPR correctly identifies functionally specialised SLs, correctly predicts known operons and detects plausible novel operons.ConclusionsSLIDR and SLOPPR are flexible tools that will accelerate research into the evolutionary dynamics of SL trans-splicing and operons throughout Eukarya and improve gene discovery and annotation for a wide range of eukaryotic genomes. Both pipelines are implemented in Bash and R and are built upon readily available software commonly installed on most bioinformatics servers. Biological insight can be gleaned even from sparse, low-coverage datasets, implying that an untapped wealth of information can be retrieved from existing RNA-Seq datasets as well as from novel full-isoform sequencing protocols as they become more widely available.

Dataset Information

SL-quant: a fast and flexible pipeline to quantify spliced leader trans-splicing events from RNA-seq data.

Publications

SL-quant: a fast and flexible pipeline to quantify spliced leader trans-splicing events from RNA-seq data.

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