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It's a bit over, is that ok? The subtle surplus from tandem alternative splicing.

ABSTRACT: Tandem alternative splice sites (TASS) form a defined class of alternative splicing and give rise to mRNA insertion/deletion variants with only small size differences. Previous work has confirmed evolutionary conservation of TASS elements while many cases show only low tissue specificity of isoform ratios. We pinpoint stochasticity and noise as important methodological issues for the dissection of TASS isoform patterns. Resolving such uncertainties, a recent report showed regulation in a cell culture system, with shifts of alternative splicing isoform ratios dependent on cell density. This novel type of regulation affects not only multiple TASS isoforms, but also other alternative splicing classes, in a concerted manner. Here, we discuss how specific regulatory network architectures may be realized through the novel regulation type and highlight the role of differential isoform functions as a key step in order to better understand the functional role of TASS.

SUBMITTER: Szafranski K

PROVIDER: S-EPMC4615896 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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It's a bit over, is that ok? The subtle surplus from tandem alternative splicing.

Szafranski Karol K Kramer Marcel M

RNA biology 20150101 2

Tandem alternative splice sites (TASS) form a defined class of alternative splicing and give rise to mRNA insertion/deletion variants with only small size differences. Previous work has confirmed evolutionary conservation of TASS elements while many cases show only low tissue specificity of isoform ratios. We pinpoint stochasticity and noise as important methodological issues for the dissection of TASS isoform patterns. Resolving such uncertainties, a recent report showed regulation in a cell cu ...[more]

PMID: 25826565

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Project description:BackgroundSubtle alternative splicing events involving tandem splice sites separated by a short (2-12 nucleotides) distance are frequent and evolutionarily widespread in eukaryotes, and a major contributor to the complexity of transcriptomes and proteomes. However, these events have been either omitted altogether in databases on alternative splicing, or only the cases of experimentally confirmed alternative splicing have been reported. Thus, a database which covers all confirmed cases of subtle alternative splicing as well as the numerous putative tandem splice sites (which might be confirmed once more transcript data becomes available), and allows to search for tandem splice sites with specific features and download the results, is a valuable resource for targeted experimental studies and large-scale bioinformatics analyses of tandem splice sites. Towards this goal we recently set up TassDB (Tandem Splice Site DataBase, version 1), which stores data about alternative splicing events at tandem splice sites separated by 3 nt in eight species.DescriptionWe have substantially revised and extended TassDB. The currently available version 2 contains extensive information about tandem splice sites separated by 2-12 nt for the human and mouse transcriptomes including data on the conservation of the tandem motifs in five vertebrates. TassDB2 offers a user-friendly interface to search for specific genes or for genes containing tandem splice sites with specific features as well as the possibility to download result datasets. For example, users can search for cases of alternative splicing where the proportion of EST/mRNA evidence supporting the minor isoform exceeds a specific threshold, or where the difference in splice site scores is specified by the user. The predicted impact of each event on the protein is also reported, along with information about being a putative target for the nonsense-mediated decay (NMD) pathway. Links are provided to the UCSC genome browser and other external resources.ConclusionTassDB2, available via http://www.tassdb.info, provides comprehensive resources for researchers interested in both targeted experimental studies and large-scale bioinformatics analyses of short distance tandem splice sites.

Project description:BackgroundCYYR1 is a recently identified gene located on human chromosome 21 whose product has no similarity to any known protein and is of unknown function. Analysis of expressed sequence tags (ESTs) have revealed high human CYYR1 expression in cells belonging to the diffuse neuroendocrine system (DNES). These cells may be the origin of neuroendocrine (NE) tumors. The aim of this study was to conduct an initial analysis of sequence, splicing and expression of the CYYR1 mRNA in human NE tumors.MethodsThe CYYR1 mRNA coding sequence (CDS) was studied in 32 NE tumors by RT-PCR and sequence analysis. A subtle alternative splicing was identified generating two isoforms of CYYR1 mRNA differing in terms of the absence (CAG- isoform, the first described mRNA for CYYR1 locus) or the presence (CAG+ isoform) of a CAG codon. When present, this specific codon determines the presence of an alanine residue, at the exon 3/exon 4 junction of the CYYR1 mRNA. The two mRNA isoform amounts were determined by quantitative relative RT-PCR in 29 NE tumors, 2 non-neuroendocrine tumors and 10 normal tissues. A bioinformatic analysis was performed to search for the existence of the two CYYR1 isoforms in other species.ResultsThe CYYR1 CDS did not show differences compared to the reference sequence in any of the samples, with the exception of an NE tumor arising in the neck region. Sequence analysis of this tumor identified a change in the CDS 333 position (T instead of C), leading to the amino acid mutation P111S. NE tumor samples showed no significant difference in either CYYR1 CAG- or CAG+ isoform expression compared to control tissues. CYYR1 CAG- isoform was significantly more expressed than CAG+ isoform in NE tumors as well as in control samples investigated. Bioinformatic analysis revealed that only the genomic sequence of Pan troglodytes CYYR1 is consistent with the possible existence of the two described mRNA isoforms.ConclusionA new "subtle" splicing isoform (CAG+) of CYYR1 mRNA, the sequence and the expression of this gene were defined in a large series of NE tumors.

Dataset Information

It's a bit over, is that ok? The subtle surplus from tandem alternative splicing.

Publications

It's a bit over, is that ok? The subtle surplus from tandem alternative splicing.

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