scholarly journals Perspective in Alternative Splicing Coupled to Nonsense-Mediated mRNA Decay

2020 ◽  
Vol 21 (24) ◽  
pp. 9424
Author(s):  
Juan F. García-Moreno ◽  
Luísa Romão
Keyword(s):  
Gene Expression ◽  
Alternative Splicing ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Translation Termination ◽  
Mrna Isoforms ◽  
Isoform Diversity ◽  
Nonsense Mediated Mrna Decay ◽  
Protein Isoform ◽  
Nonsense Mediated Rna Decay

Alternative splicing (AS) of precursor mRNA (pre-mRNA) is a cellular post-transcriptional process that generates protein isoform diversity. Nonsense-mediated RNA decay (NMD) is an mRNA surveillance pathway that recognizes and selectively degrades transcripts containing premature translation-termination codons (PTCs), thereby preventing the production of truncated proteins. Nevertheless, NMD also fine-tunes the gene expression of physiological mRNAs encoding full-length proteins. Interestingly, around one third of all AS events results in PTC-containing transcripts that undergo NMD. Numerous studies have reported a coordinated action between AS and NMD, in order to regulate the expression of several genes, especially those coding for RNA-binding proteins (RBPs). This coupling of AS to NMD (AS-NMD) is considered a gene expression tool that controls the ratio of productive to unproductive mRNA isoforms, ultimately degrading PTC-containing non-functional mRNAs. In this review, we focus on the mechanisms underlying AS-NMD, and how this regulatory process is able to control the homeostatic expression of numerous RBPs, including splicing factors, through auto- and cross-regulatory feedback loops. Furthermore, we discuss the importance of AS-NMD in the regulation of biological processes, such as cell differentiation. Finally, we analyze interesting recent data on the relevance of AS-NMD to human health, covering its potential roles in cancer and other disorders.

scholarly journals CELF RNA binding proteins promote axon regeneration in C. elegans and mammals through alternative splicing of Syntaxins

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Lizhen Chen ◽  
Zhijie Liu ◽  
Bing Zhou ◽  
Chaoliang Wei ◽  
Yu Zhou ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcriptional Regulation ◽  
Alternative Splicing ◽  
Binding Proteins ◽  
Rna Binding ◽  
Axon Regeneration ◽  
Rna Binding Proteins ◽  
Mrna Isoforms ◽  
C Elegans ◽  
Mrna Targets

Axon injury triggers dramatic changes in gene expression. While transcriptional regulation of injury-induced gene expression is widely studied, less is known about the roles of RNA binding proteins (RBPs) in post-transcriptional regulation during axon regeneration. In C. elegans the CELF (CUGBP and Etr-3 Like Factor) family RBP UNC-75 is required for axon regeneration. Using crosslinking immunoprecipitation coupled with deep sequencing (CLIP-seq) we identify a set of genes involved in synaptic transmission as mRNA targets of UNC-75. In particular, we show that UNC-75 regulates alternative splicing of two mRNA isoforms of the SNARE Syntaxin/unc-64. In C. elegans mutants lacking unc-75 or its targets, regenerating axons form growth cones, yet are deficient in extension. Extending these findings to mammalian axon regeneration, we show that mouse Celf2 expression is upregulated after peripheral nerve injury and that Celf2 mutant mice are defective in axon regeneration. Further, mRNAs for several Syntaxins show CELF2 dependent regulation. Our data delineate a post-transcriptional regulatory pathway with a conserved role in regenerative axon extension.

scholarly journals Position Specific Alternative Splicing and Gene Expression Profiles Along the Tonotopic Axis of Chick Cochlea

2021 ◽  
Vol 8 ◽  
Author(s):  
Heiyeun Koo ◽  
Jae Yeon Hwang ◽  
Sungbo Jung ◽  
Hyeyoung Park ◽  
Jinwoong Bok ◽  
...  
Keyword(s):  
Gene Expression ◽  
Alternative Splicing ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Expression Profiles ◽  
Single Gene ◽  
Gene Expression Profiles ◽  
Binding Motif ◽  
Dependent Manner ◽  
Mrna Isoforms

Alternative splicing (AS) refers to the production of multiple mRNA isoforms from a single gene due to alternative selection of exons or splice sites during pre-mRNA splicing. It is a primary mechanism of gene regulation in higher eukaryotes and significantly expands the functional complexity of eukaryotic organisms, contributing to animal development and disease. Recent studies have shown that AS also influences functional diversity by affecting the transcriptomic and proteomic profiles in a position-dependent manner in a single organ. The peripheral hearing organ, the cochlea, is organized to detect sounds at different frequencies depending on its location along the longitudinal axis. This unique functional configuration, the tonotopy, is known to be facilitated by differential gene expression along the cochlear duct. We profiled transcriptome-wide gene expression and AS changes that occur within the different positions of chick cochlea. These analyses revealed distinct gene expression profiles and AS, including a splicing program that is unique to tonotopy. Changes in the expression of splicing factors PTBP3, ESRP1, and ESRP2 were demonstrated to contribute to position-specific AS. RNA-binding motif enrichment analysis near alternatively spliced exons provided further insight into the combinatorial regulation of AS at different positions by different RNA-binding proteins. These data, along with gene ontology (GO) analysis, represent a comprehensive analysis of the dynamic regulation of AS at different positions in chick cochlea.

scholarly journals CELF2 regulates the species-specific alternative splicing of TREM2

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Motoaki Yanaizu ◽  
Chika Washizu ◽  
Nobuyuki Nukina ◽  
Jun-ichi Satoh ◽  
Yoshihiro Kino
Keyword(s):  
Alternative Splicing ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Full Length ◽  
Splicing Regulation ◽  
Nonsense Mediated Mrna Decay ◽  
Specific Alternative ◽  
Species Specific ◽  
Human And Mouse ◽  
Paralogous Proteins

Abstract Genetic variations of TREM2 have been implicated as a risk factor of Alzheimer’s disease (AD). Recent studies suggest that the loss of TREM2 function compromises microglial responses to the accumulation of amyloid beta. Previously, we found that exon 3 of TREM2 is an alternative exon whose skipping leads to a reduction in full-length TREM2 protein by inducing nonsense-mediated mRNA decay. Here, we aimed to identify factors regulating TREM2 splicing. Using a panel of RNA-binding proteins, we found that exon 3 skipping of TREM2 was promoted by two paralogous proteins, CELF1 and CELF2, which were both linked previously with risk loci of AD. Although the overexpression of both CELF1 and CELF2 enhanced exon 3 skipping, only CELF2 reduced the expression of full-length TREM2 protein. Notably, the TREM2 ortholog in the green monkey, but not in the mouse, showed alternative splicing of exon 3 like human TREM2. Similarly, splicing regulation of exon 3 by CELF1/2 was found to be common to humans and monkeys. Using chimeric minigenes of human and mouse TREM2, we mapped a CELF-responsive sequence within intron 3 of human TREM2. Collectively, our results revealed a novel regulatory factor of TREM2 expression and highlighted a species-dependent difference of its regulation.

Stage-Specific Switches in Alternative Pre-mRNA Splicing during Late Erythropoiesis Are Conserved from Mouse to Human

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 531-531
Author(s):  
Sherry Gee ◽  
Jonathan Villalobos ◽  
Miki Yamamoto ◽  
Tyson A. Clark ◽  
Jeong-Ah Kang ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Mrna Splicing ◽  
Protein Isoforms ◽  
Comparative Genomic ◽  
Erythroid Progenitors ◽  
Mrna Isoforms ◽  
Stop Codons ◽  
Primary Mouse

Abstract Spatial and temporal regulation of alternative pre-mRNA splicing determines which exons are incorporated into mature mRNA, modulating mRNA coding capacity to ensure synthesis of appropriate protein isoforms throughout normal differentiation and development. During erythropoiesis, a stage-specific switch in pre-mRNA splicing activates incorporation of protein 4.1R exon 16, thereby increasing 4.1R affinity for spectrin and actin and mechanically strengthening red blood cell membranes. We are exploring the hypothesis that stage-specific changes in pre-mRNA splicing regulate expression of other critical genes during terminal erythropoiesis. Last year we described exon microarray and RT-PCR studies that revealed several novel pre-mRNA splicing switches in terminally differentiating human erythroid progenitors. These alternative splicing events involved well-annotated exons with consensus exon-intron boundaries, supporting a model in which these events represent a regulated alternative splicing program rather than a breakdown of splicing integrity in late erythropoiesis. Here we report additional evidence for this model by showing that several erythroid stage-specific switches in alternative pre-mRNA splicing are conserved between human and mouse. Primary mouse splenic erythroblasts from FVA-infected mice were cultured in vitro under differentiation conditions and used as the source of RNA for analysis of murine erythroid splicing events. From a total of seven internal cassette exons whose splicing was activated in late human erythroblasts, five exhibited an analogous splicing switch in murine erythroblasts. Comparative genomic analysis showed that these alternative exons are embedded in regions of unusually high sequence conservation among vertebrate species, suggesting that important regulatory signals are contained within the adjacent introns. Indeed, the flanking introns for several of these exons contain binding motifs for Fox2, an RNA binding protein and known splicing regulator for many tissue-specific splicing events. Further analysis of the conserved erythroid splicing events revealed the following: three splicing switches occur in transcripts encoding RNA binding proteins (MBNL2, HNRPLL, and SNRP70), suggesting significant changes in the RNA processing machinery of late erythroblasts; and three of these alternative exons encode premature stop codons that could induce nonsense mediated decay (NMD) and contribute to down-regulation of these genes during terminal erythropoiesis. Consistent with the latter hypothesis, inhibition of NMD in murine erythroblast cultures led to increased accumulation of mRNA isoforms containing the premature stop codons. Together these results suggest the existence of a highly regulated alternative splicing program that is critical for late erythroid differentiation.

scholarly journals Dynamically expressed single ELAV/Hu orthologue elavl2 of bees is required for learning and memory

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Pinar Ustaoglu ◽  
Jatinder Kaur Gill ◽  
Nicolas Doubovetzky ◽  
Irmgard U. Haussmann ◽  
Thomas C. Dix ◽  
...  
Keyword(s):  
Gene Expression ◽  
Alternative Splicing ◽  
Learning And Memory ◽  
Memory Consolidation ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Brain Regions ◽  
Mrna Processing ◽  
Gene Expression Response ◽  
Expression Response

AbstractChanges in gene expression are a hallmark of learning and memory consolidation. Little is known about how alternative mRNA processing, particularly abundant in neuron-specific genes, contributes to these processes. Prototype RNA binding proteins of the neuronally expressed ELAV/Hu family are candidates for roles in learning and memory, but their capacity to cross-regulate and take over each other’s functions complicate substantiation of such links. Honey bees Apis mellifera have only one elav/Hu family gene elavl2, that has functionally diversified by increasing alternative splicing including an evolutionary conserved microexon. RNAi knockdown demonstrates that ELAVL2 is required for learning and memory in bees. ELAVL2 is dynamically expressed with altered alternative splicing and subcellular localization in mushroom bodies, but not in other brain regions. Expression and alternative splicing of elavl2 change during memory consolidation illustrating an alternative mRNA processing program as part of a local gene expression response underlying memory consolidation.

scholarly journals Phosphorylation-Mediated Regulation of Alternative Splicing in Cancer

2013 ◽  
Vol 2013 ◽  
pp. 1-15 ◽  
Author(s):  
Chiara Naro ◽  
Claudio Sette
Keyword(s):  
Gene Expression ◽  
Alternative Splicing ◽  
Posttranslational Modifications ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Splice Variants ◽  
Single Gene ◽  
Regulation Of Gene Expression ◽  
Eukaryotic Cells ◽  
Macromolecular Complex

Alternative splicing (AS) is one of the key processes involved in the regulation of gene expression in eukaryotic cells. AS catalyzes the removal of intronic sequences and the joining of selected exons, thus ensuring the correct processing of the primary transcript into the mature mRNA. The combinatorial nature of AS allows a great expansion of the genome coding potential, as multiple splice-variants encoding for different proteins may arise from a single gene. Splicing is mediated by a large macromolecular complex, the spliceosome, whose activity needs a fine regulation exerted bycis-acting RNA sequence elements andtrans-acting RNA binding proteins (RBP). The activity of both core spliceosomal components and accessory splicing factors is modulated by their reversible phosphorylation. The kinases and phosphatases involved in these posttranslational modifications significantly contribute to AS regulation and to its integration in the complex regulative network that controls gene expression in eukaryotic cells. Herein, we will review the major canonical and noncanonical splicing factor kinases and phosphatases, focusing on those whose activity has been implicated in the aberrant splicing events that characterize neoplastic transformation.

scholarly journals RBM4 down-regulates PTB and antagonizes its activity in muscle cell–specific alternative splicing

2011 ◽  
Vol 193 (3) ◽  
pp. 509-520 ◽  
Author(s):  
Jung-Chun Lin ◽  
Woan-Yuh Tarn
Keyword(s):  
Alternative Splicing ◽  
Cell Differentiation ◽  
Muscle Cell ◽  
Rna Binding ◽  
Exon Skipping ◽  
Mrna Isoforms ◽  
Functional Specification ◽  
Nonsense Mediated Mrna Decay ◽  
Specific Alternative

Alternative splicing contributes largely to cell differentiation and functional specification. We previously reported that the RNA-binding protein RBM4 antagonizes the activity of splicing factor PTB to modulate muscle cell–specific exon selection of α-tropomyosin. Here we show that down-regulation of PTB and its neuronal analogue nPTB during muscle cell differentiation may involve alternative splicing-coupled nonsense-mediated mRNA decay. RBM4 regulates PTB/nPTB expression by activating exon skipping of their transcripts during myogenesis. Moreover, RBM4 and PTB target a common set of transcripts that undergo muscle cell–specific alternative splicing. Overexpression of RBM4 invariably promoted expression of muscle cell–specific isoforms, which recapitulated in vivo alternative splicing changes during muscle differentiation, whereas PTB acted oppositely to RBM4 in expression of mRNA isoforms specific for late-stage differentiation. Therefore, RBM4 may synergize its effect on muscle cell–specific alternative splicing by down-regulating PTB expression and antagonizing the activity of PTB in exon selection, which highlights a hierarchical role for RBM4 in a splicing cascade that regulates myogenesis.

scholarly journals PTBP1 mRNA isoforms and regulation of their translation

2018 ◽  
Author(s):  
Luisa M Arake de Tacca ◽  
Mia C Pulos ◽  
Stephen N Floor ◽  
Jamie Cate
Keyword(s):  
Cell Cycle ◽  
Alternative Splicing ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Translation Initiation Factor ◽  
Protein Isoforms ◽  
Initiation Factor ◽  
Dependent Manner ◽  
Mrna Isoforms

Polypyrimidine tract-binding proteins (PTBPs) are RNA binding proteins that regulate a number of post-transcriptional events. Human PTBP1 transits between the nucleus and cytoplasm and is thought to regulate RNA processes in both. However, information about PTBP1 mRNA isoforms and regulation of PTPB1 expression remain incomplete. Here we mapped the major PTBP1 mRNA isoforms in HEK293T cells, and identified alternative 5' and 3' untranslated regions (5' UTRs, 3' UTRs) as well as alternative splicing patterns in the protein coding region. We also assessed how the observed PTBP1 mRNA isoforms contribute to PTBP1 expression in different phases of the cell cycle. Previously, PTBP1 mRNAs were shown to crosslink to eukaryotic translation initiation factor 3 (eIF3). We find that eIF3 binds differently to each PTBP1 mRNA isoform in a cell cycle-dependent manner. We also observe a strong correlation between eIF3 binding to PTBP1 mRNAs and repression of PTBP1 levels during the S phase of the cell cycle. Our results provide evidence of translational regulation of PTBP1 protein levels during the cell cycle, which may affect downstream regulation of alternative splicing and translation mediated by PTBP1 protein isoforms.

scholarly journals Dynamically expressed ELAV is required for learning and memory in bees

2021 ◽  
Author(s):  
Pinar Ustaoglu ◽  
Jatinder Kaur Gill ◽  
Nicolas Doubovetzky ◽  
Irmgard Haussmann ◽  
Jean-Marc Devaud ◽  
...  
Keyword(s):  
Gene Expression ◽  
Alternative Splicing ◽  
Learning And Memory ◽  
Honey Bee ◽  
Memory Consolidation ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Mrna Processing ◽  
Early Gene ◽  
Gene Expression Response

Changes in gene expression are a hallmark of learning and memory consolidation. Little is known about how alternative mRNA processing, particularly abundant in neuron-specific genes, contributes to these processes. Prototype RNA binding proteins of the neuronally expressed ELAV/Hu family are candidates for roles in learning and memory, but their capacity to cross-regulate and take over each others functions complicate substantiation of such links. Therefore, we focused on honey bees, which have only a single elav family gene. We find that honey bee elav contains a microexon, which is evolutionary conserved between invertebrates and humans. RNAi knockdown of elav demonstrates that ELAV is required for learning and memory in bees. Indicative of a role as immediate early gene, ELAV is dynamically expressed with altered alternative splicing and subcellular localization in mushroom bodies, but not in other brain parts. Expression and alternative splicing of elav change during memory consolidation illustrating an alternative mRNA processing program as part of a local gene expression response underlying memory formation. Although the honey bee genome encodes only a single elav gene, functional diversification is achieved by alternative splicing.

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