Global donor and acceptor splicing site kinetics in human cells
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE129635 | GEO | 2019/04/12
REPOSITORIES: GEO
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Project description:RNA splicing is an essential part of eukaryotic gene expression. Although the mechanism of splicing has been extensively studied in vitro, in vivo kinetics for the two-step splicing reaction remain poorly understood. Here, we combine transient transcriptome sequencing (TT-seq) and mathematical modeling to quantify RNA metabolic rates at donor and acceptor splice sites across the human genome. Splicing occurs in the range of minutes and is limited by the speed of RNA polymerase elongation. Splicing kinetics strongly depends on the position and nature of nucleotides flanking splice sites, and on structural interactions between unspliced RNA and small nuclear RNAs in spliceosomal intermediates. Finally, we introduce the 'yield' of splicing as the efficiency of converting unspliced to spliced RNA and show that it is highest for mRNAs and independent of splicing kinetics. These results lead to quantitative models describing how splicing rates and yield are encoded in the human genome.
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Project description:In this work, we quantified mRNA flow rates between subcellular compartments in mouse embryonic stem cells. Combining metabolic RNA labeling, biochemical cell fractionation and RNA sequencing with mathematical modeling we were able to determine the kinetic rates of nuclear pre-, nuclear mature, cytosolic and membrane mRNA derived from more than 9000 protein-coding genes. For more than 5000 genes, we additionally estimated the transcript elongation rate. For most of the transcripts, mature nuclear half-lives are the longest, suggesting nuclear retention to be the rate-limiting step in the mRNA life cycle. Genes encoding transcription factors and immediate early genes possess fast kinetic rates, specifically a short nuclear half-life. Differentially localized mRNAs exhibit distinct combinations of rate constants, suggesting modular control within subcellular compartments. We show that membrane stability is high for membrane-localized mRNA and that cytosolic stability is high for cytosol-localized mRNA. Genes encoding target signals, such as signal peptides or transmembrane domains, have low cytosolic and high membrane half-lives with only slight differences between target signals. Nuclear-encoded mitochondrial proteins show long nuclear mature half-lives and otherwise similar features of cytoplasmic kinetics that do not resemble co-translational targeting to the mitochondria.
2024-09-17 | GSE252199 | GEO
Project description:In this work, we quantified mRNA flow rates between subcellular compartments in mouse embryonic stem cells. Combining metabolic RNA labeling, biochemical cell fractionation and RNA sequencing with mathematical modeling we were able to determine the kinetic rates of nuclear pre-, nuclear mature, cytosolic and membrane mRNA derived from more than 9000 protein-coding genes. For more than 5000 genes, we additionally estimated the transcript elongation rate. For most of the transcripts, mature nuclear half-lives are the longest, suggesting nuclear retention to be the rate-limiting step in the mRNA life cycle. Genes encoding transcription factors and immediate early genes possess fast kinetic rates, specifically a short nuclear half-life. Differentially localized mRNAs exhibit distinct combinations of rate constants, suggesting modular control within subcellular compartments. We show that membrane stability is high for membrane-localized mRNA and that cytosolic stability is high for cytosol-localized mRNA. Genes encoding target signals, such as signal peptides or transmembrane domains, have low cytosolic and high membrane half-lives with only slight differences between target signals. Nuclear-encoded mitochondrial proteins show long nuclear mature half-lives and otherwise similar features of cytoplasmic kinetics that do not resemble co-translational targeting to the mitochondria.
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Project description:Approximately 30% of alleles causing genetic disorders generate premature termination codons (PTCs), which are usually associated with severe phenotypes. However, bypassing the deleterious stop codon can lead to a mild disease outcome. Splicing at NAGNAG tandem splice sites has been reported to result in insertion or deletion (indel) of three nucleotides. We identified such a mechanism as the origin of the mild to asymptomatic phenotype observed in cystic fibrosis patients homozygous for the E831X mutation (2623G>T) in the CFTR gene. Analyses performed on nasal epithelial cell mRNA detected three distinct isoforms, a considerably more complex situation than expected for a single nucleotide substitution. Structure-function studies and in silico analyses provided the first experimental evidence of an indel of a stop codon by alternative splicing at a NAGNAG acceptor site. In addition to contributing to proteome plasticity, alternative splicing at a NAGNAG tandem site can thus remove a disease-causing UAG stop codon. This molecular study reveals a naturally occurring mechanism where the effect of either modifier genes or epigenetic factors could be suspected. This finding is of importance for genetic counseling as well as for deciding appropriate therapeutic strategies.
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2007-09-29 | E-GEOD-7574 | biostudies-arrayexpress
Project description:DNA microarray technology is a powerful tool for getting the overview of gene expression in biological samples. Although the successful application of microarray-based expression analysis was demonstrated in a number of applications, the main problem with this approach is the fact that expression levels deduced from hybridization experiments do not necessarily correlate with RNA concentrations. Moreover, oligonucleotide probes corresponding to the same gene can give different hybridization signals. Apart from cross-hybridizations and differential splicing, this could be due to secondary structures of probes or targets. In addition, for low copy genes, hybridization equilibrium may be reached after hybridization times much longer than the one commonly used (overnight, 15 hours). Thus, hybridization signals could depend on kinetic properties of the probe, which may vary between different oligonucleotide probes immobilized on the same microarray. To validate these hypothesis, on-chip hybridization kinetics and duplexes thermostability analysis were performed using oligonucleotide microarrays containing 50-mer probes corresponding to mouse genes. We demonstrate that differences in hybridization kinetics between the probes can influence the interpretation of expression data. Ways to improve the reliability of microarray-based expression analysis are discussed. Keywords: kinetics, gene expression, microarrays
2007-09-30 | GSE7574 | GEO
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