Alternative polyadenylation mediates genetic regulation of gene expression
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE138197 | GEO | 2020/06/23
REPOSITORIES: GEO
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Project description:Differences in gene regulation contribute to phenotypic differences between humans and other primates. While co-transcriptional gene regulatory mechanisms such as alternative polyadenylation (APA) can help explain how variation in gene regulation manifests, such mechanisms remain understudied. We measured polyadenylation site (PAS) usage in a panel of 6 human and 6 chimpanzee lymphoblastoid cell lines (LCLs). While APA is largely conserved between humans and chimpanzees, genes with divergent APA patterns are enriched among differentially expressed and differentially translated genes. Differential usage of 3’ UTR and intronic PAS are both significantly correlated with differential mRNA expression effect sizes but in opposite directions. For many genes, there is one PAS dominant, meaning it is used much more often than others. The dominant PAS for these gene is overwhelmingly shared between species, however, differences in dominant PAS are enriched for genes with expression differences. Finally, through post-translational mechanisms, we believe APA contributes to genes differentially expressed at the protein level but not in mRNA. As this is the first primate comparative study of APA, our study establishes APA as a key mechanism underlying the genetic regulation of gene and protein expression levels in primates.
2021-01-22 | GSE155245 | GEO
Project description:Alternative polyadenylation (APA) creates distinct transcripts from the same gene by cleaving the pre-mRNA at poly(A) sites that can lie within the 3' UTR, introns, or exons. Most studies focus on APA within the 3' UTR, but here we show that CPSF6 insufficiency alters protein levels and causes a developmental syndrome by deregulating APA throughout the transcript. In neonatal humans and zebrafish larvae, CPSF6 insufficiency shifts poly(A) site usage between the 3'UTR and internal sites in a pathway-specific manner. Genes associated with neuronal function undergo mostly intronic APA, reducing their expression, while genes associated with heart and skeletal function mostly undergo 3' UTR APA and are upregulated. This suggests that, in healthy conditions, cells toggle between internal and 3'UTR APA to modulate protein expression.
2022-11-21 | MSV000090759 | MassIVE
Project description:Genetic variants that impact gene regulation are important contributors to human phenotypic variation. For this reason, considerable efforts have been made to identify genetic associations with differences in mRNA levels of nearby genes, namely, cis expression quantitative trait loci (eQTLs). The phenotypic consequences of eQTLs are presumably due, in most cases, to their ultimate effects on protein expression levels. Yet, only few studies have quantified the impact of genetic variation on proteins levels directly. It remains unclear how faithfully eQTLs are reflected at the protein level, and whether there is a significant layer of cis regulatory variation acting primarily on translation or steady state protein levels. To address these questions, we measured ribosome occupancy by high-throughput sequencing, and relative protein levels by high-resolution quantitative mass spectrometry, in a panel of lymphoblastoid cell lines (LCLs) in which we had previously measured transcript expression using RNA sequencing. We then mapped genetic variants that are associated with changes in transcript expression (eQTLs), ribosome occupancy (rQTLs), or protein abundance (pQTLs). Most of the QTLs we detected are associated with transcript expression levels, with consequent effects on ribosome and protein levels. However, we found that eQTLs tend to have significantly reduced effect sizes on protein levels, suggesting that their potential impact on downstream phenotypes is often attenuated or buffered. Additionally, we confirmed the presence of a class of cis QTLs that specifically affect protein abundance with little or no effect on mRNA levels; most of these QTLs have little effect on ribosome occupancy, and hence may arise from differences in post-translational regulation. We measured level of translation transcriptome-wide in lymphoblastoid cell lines derived from 72 HapMap Yoruba individuals using ribosome profiling assay, for which we have transcript level, protein level (62 out of 72) and genotype information collected.
2014-12-19 | E-GEOD-61742 | biostudies-arrayexpress
Project description:Most eukaryotic genes express alternative polyadenylation (APA) isoforms with different 3’UTR sizes. The APA profile varies across tissue types and under different growth and differentiation conditions. Here we report that, unlike many other cell differentiation lineages, differentiation of syncytiotrophoblasts (SCTs) elicits widespread 3’UTR shortening, as shown in multiple in vitro trophoblast differentiation models as well as in single placental cells at different stages of pregnancy. We show that the 3’UTR shortening is unrelated to cell proliferation, a feature previously associated with 3’UTR size control, but rather accompanies increased cell function in protein secretion. In addition, 3’UTR shortening correlates with increased transcript abundance and is coupled with enhanced intronic APA site usage, suggesting activation of 3’ end processing in SCT differentiation. Together, our data indicate that SCTs utilize APA to express transcripts with short 3’UTRs, which may enhance hormone production and secretion, contributing to their functions in pregnancy.
2020-05-15 | GSE138759 | GEO
Project description:Quantitative trait loci analyses have revealed an important role for genetic variants in regulating alternative splicing (AS) and alternative cleavage and polyadenylation (APA) in humans. Yet, these studies are generally performed with mature mRNA, so they report on the outcome rather than the processes of RNA maturation and thus may overlook how variants directly modulate pre-mRNA processing. The order in which the many introns of a human gene are removed can substantially influence AS, while nascent RNA polyadenylation can affect RNA stability and decay. However, how splicing order and poly(A) tail length are regulated by genetic variation has never been explored. Here, we used direct RNA nanopore sequencing to investigate allele-specific pre-mRNA maturation in 12 human lymphoblastoid cell lines. We found frequent splicing order differences between alleles and uncovered significant single nucleotide polymorphism (SNP)-splicing order associations in 17 genes. This included SNPs located in or near splice sites as well as more distal intronic and exonic SNPs. Moreover, several genes showed allele-specific poly(A) tail lengths, many of which also had a skewed allelic abundance ratio. HLA class I transcripts, which encode proteins that play an essential role in antigen presentation, showed the most allele-specific splicing orders, which frequently co-occurred with allele-specific AS, APA or poly(A) tail length differences. Together, our results expose new layers of genetic regulation of pre-mRNA maturation and highlight the power of long-read RNA sequencing for allele-specific analyses.
2024-10-22 | GSE256190 | GEO
Project description:The DNA damage response (DDR) involves coordinated control of gene expression and DNA repair. Using deep sequencing we found widespread changes of alternative cleavage and polyadenylation (APA) site usage upon UV-treatment in mammalian cells. APA regulation in the 3’ untranslated region (3’UTR) is substantial, leading to both shortening and lengthening of 3’UTRs. Interestingly, a strong activation of intronic APA sites is detected, resulting in widespread expression of truncated transcripts. Intronic APA events are biased to the 5’ end of genes and affect gene groups with important functions in DDR. Moreover, intronic APA site activation during DDR correlates with a decrease in U1 snRNA levels, and this is reversed by U1 snRNA overexpression. Importantly, U1 snRNA overexpression decreases UV-induced apoptosis. Together, these studies describe a significant gene regulatory scheme in DDR where U1 snRNP impacts gene expression via APA.
2016-05-01 | GSE71801 | GEO
Project description:Alternative cleavage and polyadenylation (APA) results in mRNA isoforms containing different 3’ untranslated regions (3’UTRs) and/or coding sequences. How core cleavage and polyadenylation (C/P) factors regulate APA is not well understood. Using siRNA knockdown coupled with deep sequencing, we found that several C/P factors can play significant roles in 3’UTR-APA. Whereas Pcf11 and Fip1 enhance usage of proximal poly(A) sites (pAs), CFI-25/68, PABPN1, and PABPC1 promote usage of distal pAs. Strong cis element biases were found for pAs regulated by CFI or Fip1, and the distance between pAs plays an important role in APA regulation. In addition, intronic pAs are substantially regulated by splicing factors, with U1 mostly influencing C/P events in 5’ introns and U2 impacting those in efficiently spliced introns. Furthermore, PABPN1 regulates expression of transcripts with pAs near the transcription start site, a property possibly related to its role in RNA degradation. Finally, we found that groups of APA events regulated by C/P factors are also modulated in cell differentiation and development with distinct trends. Together, our results indicate that the abundance of different C/P factors and splicing factors plays diverse roles in APA, and is relevant to APA regulation in biological conditions. knockdown experiments of 23 C/P factors, 3 splicing factors and U1D in mouse C2C12 myoblast cells
2015-04-01 | E-GEOD-62001 | biostudies-arrayexpress
Project description:Poly(A) binding protein nuclear 1 (PABPN1) is a multifunctional regulator of mRNA processing. PABPN1 inhibits alternative polyadenylation (APA), and in conditions with reduced PABPN1 levels APA utilization causes genome-wide mRNA dysregulation. PABPN1 levels decline from midlife onwards in Oculopharyngeal Muscular Dystrophy (OPMD) and in aged muscles. Reduced PABPN1 levels cause muscle atrophy by altering mRNA levels of the ubiquitin proteasome system. The effect of PABPN1-mediated APA utilization on the proteome has not been investigated yet. We report the PABPN1-mediated proteome in Tibialis anterior (TA) mouse muscles, signifying functional impact for the mitochondria, cytoskeleton and translation cellular machineries. Central nucleation and split myofibers marked PABPN1-derived muscle histology. We show that up-regulation of the cytoskeletal proteins: Murc, Pfn1 and Csrp3, is highly associated with PABPN1-mediated muscle pathology and with reduced PABPN1 levels. Elevation of PABPN1 levels by sirtinol treatment reversed muscle pathology and restored levels of those cytoskeletal proteins. We suggest that restoration of PABPN1 levels in aged muscles could be a novel therapeutic strategy to mitigate muscle waste.
2020-07-06 | PXD004865 | Pride
Project description:DNA methylation is an important epigenetic regulator of gene expression. Recent studies have revealed widespread associations between genetic variation and methylation levels. However, the mechanistic links between genetic variation and methylation remain unclear. To begin addressing this gap, we collected methylation data at ~300,000 loci in lymphoblastoid cell lines (LCLs) from 64 HapMap Yoruba individuals, and genome-wide bisulfite sequence data in ten of these individuals. We identified (at an FDR of 10%) 13,915 *cis* methylation QTLs (meQTLs), i.e., CpG sites in which changes in DNA methylation are associated with genetic variation at proximal loci. We found that meQTLs are frequently associated with changes in methylation at multiple CpGs across regions of up to 3 kb. Interestingly, meQTLs are also frequently associated with variation in other properties of gene regulation, including histone modifications, DNase I accessibility, chromatin accessibility, and expression levels of nearby genes. These observations suggest that genetic variants may lead to coordinated molecular changes in all of these regulatory phenotypes. One plausible driver of coordinated changes in different regulatory mechanisms is variation in transcription factor (TF) binding. Indeed, we found that SNPs that change predicted TF binding affinities are significantly enriched for associations with DNA methylation at nearby CpGs. Whole genomic DNA from 10 Yoruba HapMap individuals and spiked in unmethylated lambda phage DNA was bisuflite converted using the Invitrogen MethylCode Bisulfite Conversion Kit and sequenced using a Illumina HiSeq 2000
2014-05-09 | E-GEOD-57471 | biostudies-arrayexpress
Project description:mRNA stability plays an important role in gene expression. Here, using 3’ end sequencing of newly made and steady-state poly(A)+ RNAs, we compare transcript stability in multiple human cell lines, including HEK293T, HepG2, SH-SY5Y. We show that while mRNA stability is generally conserved across the cell lines, specific transcripts having high GC content and likely more stable secondary RNA structures are relatively more stable in SH-SY5Y cells compared to other two. These features also differentiate alternative polyadenylation (APA) 3’UTR isoforms in their stability difference in a cell type-specific manner. By analyzing cell differentiation of a neural stem cell line, we show that mRNA stability difference could contribute to gene expression changes in neurogenesis and confirms the neuronal identity of SH-SY5Y cells at gene expression and APA levels. Through comparison of APA isoforms, we show that mRNA stability control buffer the cleavage and polyadenylation site (PAS) choice in the cells studied. In addition, transcripts using intronic PAS are generally less stable, especially when the intron harboring the PAS is large and has a strong 5’ splice site, suggesting that intronic polyadenylation mostly plays a negative role in gene expression. Moreover, we found that poly(A)+ RNAs encoded by the mitochondrial genome are more stable in SH-SY5Y cells than the other two cell types, suggesting that mitochondrial RNA metabolism is distinct in neurons. Together, our results reveal multiple cell-specific mechanisms by which mRNA stability could contribute to the gene expression and APA programs that are important for cell identity.
2021-12-27 | GSE189899 | GEO