scholarly journals Frequent co-regulation of splicing and polyadenylation by RNA-binding proteins inferred with MAPP

2022 ◽  
Author(s):  
Maciej Bak ◽  
Erik van Nimwegen ◽  
Ralf Schmidt ◽  
Mihaela Zavolan ◽  
Andreas J Gruber

Maturation of eukaryotic pre-mRNAs via splicing, 3' end cleavage and polyadenylation is modulated across cell types and conditions by a variety of RNA-binding proteins (RBPs). Although over 1'500 proteins are associated with RNAs in human cells, their binding motifs, targets and functions still remain to be elucidated, especially in the complex environment of human tissues and in the context of diseases. To overcome the lack of methods for systematic and automated detection of sequence motif-guided changes in pre-mRNA processing based on RNA sequencing (RNA-seq) data we have developed MAPP (Motif Activity on Pre-mRNA Processing). We demonstrate MAPP's functionality by applying it to RNA-seq data from 284 RBP knock-down experiments in the ENCODE project, from which MAPP not only infers position-dependent impact profiles of known regulators, but also reveals RBPs that modulate both the inclusion of cassette exons and the poly(A) site choice. Among these, the Polypyrimidine Tract Binding Protein 1 (PTBP1) has a similar activity in glioblastoma samples. This highlights the ability of MAPP to unveil global regulators of mRNA processing under physiological and pathological conditions.

2001 ◽  
Vol 21 (10) ◽  
pp. 3364-3374 ◽  
Author(s):  
Sally A. Mitchell ◽  
Emma C. Brown ◽  
Mark J. Coldwell ◽  
Richard J. Jackson ◽  
Anne E. Willis

ABSTRACT It has been reported previously that the 5′ untranslated region of the mRNA encoding Apaf-1 (apoptotic protease-activating factor 1) has an internal ribosome entry site (IRES), whose activity varies widely among different cell types. Here it is shown that the Apaf-1 IRES is active in rabbit reticulocyte lysates, provided that the system is supplemented with polypyrimidine tract binding protein (PTB) and upstream of N-ras (unr), two cellular RNA binding proteins previously identified to be required for rhinovirus IRES activity. In UV cross-linking assays and electrophoretic mobility shift assays with individual recombinant proteins, the Apaf-1 IRES binds unr but not PTB; however, PTB binding occurs if unr is present. Over a range of different cell types there is a broad correlation between the activity of the Apaf-1 IRES and their content of PTB and unr. In cell lines deficient in these proteins, overexpression of PTB and unr stimulated Apaf-1 IRES function. This is the first example where an IRES in a cellular mRNA has been shown to be functionally dependent, both in vitro and in vivo, on specific cellular RNA binding proteins. Given the critical role of Apaf-1 in apoptosis, these results have important implications for the control of the apoptotic cascade.


2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Keith Jones ◽  
Ahn Phan ◽  
Chongyu Zhang ◽  
Lauren Haar ◽  
Thomas Lynch

Exosomes (Exo) are a class of extracellular vesicles and involvement of stem cell-derived Exo in cardiac repair and cardioprotection is thought to be an important in the heart. Our HYPOTHESIS Is that specific microRNAs (miRs) from mesenchymal stem cell (MSC)-derived exosomes are actively and selectively sorted into Exo by RNA binding proteins and motifs on the miR, to serve specific functions of the Exo, including Cardioprotection. Methods: We characterized the miR populations of parental MSCs and their Exo via RNA Seq and confirmed by QRT-PCR the subpopulation of miRs that is increased in Exo vs . MSC cells. We then used Multiple Em for Motif Elicitation (MEME) Version 5.3.3 and determined the predicted conserved motifs. From these, we predicted RNA binding protein sites from the literature. In parallel, we performed mass spectrometry and western blot analyses to determine RNA binding proteins in MSC and Exo. Predicting that hnRNPA2B1 was a likely RNA binding protein for the new motif, we knocked out the cognate gene (CRISPR) in MSC and evaluated the KO Exo vs. the WT Exo by RNA Seq and QRT-PCR. We performed protein and RNA pulldowns, and EMSA to validate binding of hnRNPA2B1 to several of the miRs, and investigated the effects of these miRs on cell survival after simIR and in an in vivo mouse model of MI. Results: We found a set of eight miRs that are selectively concentrated in the MSC Exo. MEME software predicted a conserved binding motif of gAGu, which is close to canonical sites for binding of hnRNPA2B1 and hnRNPA1. We determined hnRNPA2B1 was in MSC and Exo and showed KO hnRNPA2B1 cells and Exo had no compensatory perturbation of other RNA binding proteins. The KO MSC Exo show reduction of the selective sorting of the miRs of interest. Pulldowns and binding assay results verify binding of hnRNPA2B1 to both miR-486a-5p and miR-122a. Finally, we showed that miR-486a-5p is protective in H9C2 cells submitted to simIR and results in significant 68% reduction of infarct size (n=7, P=0.0175) in vivo in association with repression of PDCD4 expression and apoptosis. Conclusions: We determined that a set of miRs is selectively concentrated in MSC Exo and demonstrated the necessity of hnRNPA2B1 in that process. This appears to involve a conserved RNA sequence motif (mutational analysis underway). A major miR affected is miR-486a-5p, which is strongly cardioprotective. Our results support that miR-486a-5p is selectively concentrated in MSC Exo and contributes to cardioprotection by reducing PDCD4 activity in apoptosis.


2021 ◽  
Author(s):  
You-Liang Cheng ◽  
Hsin-Yu Hsieh ◽  
Shih-Long Tu

Background: RNA-binding proteins (RBPs) play crucial roles in various aspects of post-transcriptional gene expression; their functions can vary between tissues, cell types, developmental stages, and environmental conditions. Identifying RBP target RNAs and investigating whether they are differentially bound by RBPs in different cell types, stages, or conditions could shed light on RBP functions. Although several strategies have been designed to identify RBP targets, they involve complicated biochemical steps and require large quantities of material, and only a few studies using these techniques have been performed in plants. The TRIBE (targets of RNA binding proteins identified by editing) method was recently developed to identify RBP targets using a RBP coupled to the catalytic domain of a Drosophila RNA editing enzyme and expressing this fusion protein in vivo. The resulting novel editing events can be identified by sequencing. This technique uses little material and does not require complex biochemical steps, however it is not yet adapted for use in plants. Results: We successfully applied an optimized genome-wide TRIBE method in plants. We selected the splicing regulator polypyrimidine tract-binding protein (PTB) as a model protein for testing the TRIBE system in the moss Physcomitrium patens. We demonstrated that 13.81% of protein-coding gene transcripts in P. patens are targets of PTB. Most potential PTB binding sites are located in coding sequences and 3 prime untranslated regions, suggesting that PTB performs multiple functions besides pre-mRNA splicing in this moss. In addition, TRIBE showed reproducible results compared to other methods. Conclusions: We have developed an alternative method based on the TRIBE system to identify RBP targets in plants globally, and we provide guidance here for its application in plants.


2018 ◽  
Author(s):  
Alina Munteanu ◽  
Neelanjan Mukherjee ◽  
Uwe Ohler

AbstractMotivationRNA-binding proteins (RBPs) regulate every aspect of RNA metabolism and function. There are hundreds of RBPs encoded in the eukaryotic genomes, and each recognize its RNA targets through a specific mixture of RNA sequence and structure properties. For most RBPs, however, only a primary sequence motif has been determined, while the structure of the binding sites is uncharacterized.ResultsWe developed SSMART, an RNA motif finder that simultaneously models the primary sequence and the structural properties of the RNA targets sites. The sequence-structure motifs are represented as consensus strings over a degenerate alphabet, extending the IUPAC codes for nucleotides to account for secondary structure preferences. Evaluation on synthetic data showed that SSMART is able to recover both sequence and structure motifs implanted into 3‘UTR-like sequences, for various degrees of structured/unstructured binding sites. In addition, we successfully used SSMART on high-throughput in vivo and in vitro data, showing that we not only recover the known sequence motif, but also gain insight into the structural preferences of the RBP.AvailabilitySSMART is freely available at https://ohlerlab.mdc-berlin.de/software/SSMART_137/[email protected]


2019 ◽  
Vol 36 (7) ◽  
pp. 2134-2141
Author(s):  
Carlos Martí-Gómez ◽  
Enrique Lara-Pezzi ◽  
Fátima Sánchez-Cabo

Abstract Motivation Alternative splicing (AS) is an important mechanism in the generation of transcript diversity across mammals. AS patterns are dynamically regulated during development and in response to environmental changes. Defects or perturbations in its regulation may lead to cancer or neurological disorders, among other pathological conditions. The regulatory mechanisms controlling AS in a given biological context are typically inferred using a two-step framework: differential AS analysis followed by enrichment methods. These strategies require setting rather arbitrary thresholds and are prone to error propagation along the analysis. Results To overcome these limitations, we propose dSreg, a Bayesian model that integrates RNA-seq with data from regulatory features, e.g. binding sites of RNA-binding proteins. dSreg identifies the key underlying regulators controlling AS changes and quantifies their activity while simultaneously estimating the changes in exon inclusion rates. dSreg increased both the sensitivity and the specificity of the identified AS changes in simulated data, even at low read coverage. dSreg also showed improved performance when analyzing a collection of knock-down RNA-binding proteins’ experiments from ENCODE, as opposed to traditional enrichment methods, such as over-representation analysis and gene set enrichment analysis. dSreg opens the possibility to integrate a large amount of readily available RNA-seq datasets at low coverage for AS analysis and allows more cost-effective RNA-seq experiments. Availability and implementation dSreg was implemented in python using stan and is freely available to the community at https://bitbucket.org/cmartiga/dsreg. Supplementary information Supplementary data are available at Bioinformatics online.


2020 ◽  
Vol 21 (20) ◽  
pp. 7803
Author(s):  
Julie Miro ◽  
Anne-Laure Bougé ◽  
Eva Murauer ◽  
Emmanuelle Beyne ◽  
Dylan Da Cunha ◽  
...  

The Duchenne muscular dystrophy (DMD) gene has a complex expression pattern regulated by multiple tissue-specific promoters and by alternative splicing (AS) of the resulting transcripts. Here, we used an RNAi-based approach coupled with DMD-targeted RNA-seq to identify RNA-binding proteins (RBPs) that regulate splicing of its skeletal muscle isoform (Dp427m) in a human muscular cell line. A total of 16 RBPs comprising the major regulators of muscle-specific splicing events were tested. We show that distinct combinations of RBPs maintain the correct inclusion in the Dp427m of exons that undergo spatio-temporal AS in other dystrophin isoforms. In particular, our findings revealed the complex networks of RBPs contributing to the splicing of the two short DMD exons 71 and 78, the inclusion of exon 78 in the adult Dp427m isoform being crucial for muscle function. Among the RBPs tested, QKI and DDX5/DDX17 proteins are important determinants of DMD exon inclusion. This is the first large-scale study to determine which RBP proteins act on the physiological splicing of the DMD gene. Our data shed light on molecular mechanisms contributing to the expression of the different dystrophin isoforms, which could be influenced by a change in the function or expression level of the identified RBPs.


BMC Genomics ◽  
2013 ◽  
Vol 14 (1) ◽  
pp. 822 ◽  
Author(s):  
Nabil M Wilf ◽  
Adam J Reid ◽  
Joshua P Ramsay ◽  
Neil R Williamson ◽  
Nicholas J Croucher ◽  
...  

2018 ◽  
Author(s):  
Jin Li ◽  
Su-Ping Deng ◽  
Jacob Vieira ◽  
James Thomas ◽  
Valerio Costa ◽  
...  

AbstractRNA-binding proteins may play a critical role in gene regulation in various diseases or biological processes by controlling post-transcriptional events such as polyadenylation, splicing, and mRNA stabilization via binding activities to RNA molecules. Due to the importance of RNA-binding proteins in gene regulation, a great number of studies have been conducted, resulting in a large amount of RNA-Seq datasets. However, these datasets usually do not have structured organization of metadata, which limits their potentially wide use. To bridge this gap, the metadata of a comprehensive set of publicly available mouse RNA-Seq datasets with perturbed RNA-binding proteins were collected and integrated into a database called RBPMetaDB. This database contains 278 mouse RNA-Seq datasets for a comprehensive list of 163 RNA-binding proteins. These RNA-binding proteins account for only ∼10% of all known RNA-binding proteins annotated in Gene Ontology, indicating that most are still unexplored using high-throughput sequencing. This negative information provides a great pool of candidate RNA-binding proteins for biologists to conduct future experimental studies. In addition, we found that DNA-binding activities are significantly enriched among RNA-binding proteins in RBPMetaDB, suggesting that prior studies of these DNA- and RNA-binding factors focus more on DNA-binding activities instead of RNA-binding activities. This result reveals the opportunity to efficiently reuse these data for investigation of the roles of their RNA-binding activities. A web application has also been implemented to enable easy access and wide use of RBPMetaDB. It is expected that RBPMetaDB will be a great resource for improving understanding of the biological roles of RNA-binding proteins.Database URL: http://rbpmetadb.yubiolab.org


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