scholarly journals Exon junction complex proteins bind nascent transcripts independently of pre-mRNA splicing in Drosophila melanogaster

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Subhendu Roy Choudhury ◽  
Anand K Singh ◽  
Tina McLeod ◽  
Marco Blanchette ◽  
Boyun Jang ◽  
...  
Keyword(s):  
Specific Interaction ◽  
Polytene Chromosomes ◽  
Exon Junction Complex ◽  
Exon Junction ◽  
Cell Extracts ◽  
Intronless Genes ◽  
Core Proteins ◽  
Central Protein ◽  
Nascent Transcripts

Although it is currently understood that the exon junction complex (EJC) is recruited on spliced mRNA by a specific interaction between its central protein, eIF4AIII, and splicing factor CWC22, we found that eIF4AIII and the other EJC core proteins Y14 and MAGO bind the nascent transcripts of not only intron-containing but also intronless genes on Drosophila polytene chromosomes. Additionally, Y14 ChIP-seq demonstrates that association with transcribed genes is also splicing-independent in Drosophila S2 cells. The association of the EJC proteins with nascent transcripts does not require CWC22 and that of Y14 and MAGO is independent of eIF4AIII. We also show that eIF4AIII associates with both polysomal and monosomal RNA in S2 cell extracts, whereas Y14 and MAGO fractionate separately. Cumulatively, our data indicate a global role of eIF4AIII in gene expression, which would be independent of Y14 and MAGO, splicing, and of the EJC, as currently understood.

scholarly journals CASC3 promotes transcriptome-wide activation of nonsense-mediated decay by the exon junction complex

2020 ◽  
Vol 48 (15) ◽  
pp. 8626-8644 ◽  
Author(s):  
Jennifer V Gerbracht ◽  
Volker Boehm ◽  
Thiago Britto-Borges ◽  
Sebastian Kallabis ◽  
Janica L Wiederstein ◽  
...  
Keyword(s):  
Exon Junction Complex ◽  
Core Component ◽  
Mrna Isoforms ◽  
Nonsense Mediated Decay ◽  
Exon Junction ◽  
Endonucleolytic Cleavage ◽  
Core Proteins ◽  
Messenger Ribonucleoprotein ◽  
Cytoplasmic Processes

Abstract The exon junction complex (EJC) is an essential constituent and regulator of spliced messenger ribonucleoprotein particles (mRNPs) in metazoans. As a core component of the EJC, CASC3 was described to be pivotal for EJC-dependent nuclear and cytoplasmic processes. However, recent evidence suggests that CASC3 functions differently from other EJC core proteins. Here, we have established human CASC3 knockout cell lines to elucidate the cellular role of CASC3. In the knockout cells, overall EJC composition and EJC-dependent splicing are unchanged. A transcriptome-wide analysis reveals that hundreds of mRNA isoforms targeted by nonsense-mediated decay (NMD) are upregulated. Mechanistically, recruiting CASC3 to reporter mRNAs by direct tethering or via binding to the EJC stimulates mRNA decay and endonucleolytic cleavage at the termination codon. Building on existing EJC-NMD models, we propose that CASC3 equips the EJC with the persisting ability to communicate with the NMD machinery in the cytoplasm. Collectively, our results characterize CASC3 as a peripheral EJC protein that tailors the transcriptome by promoting the degradation of EJC-dependent NMD substrates.

scholarly journals CASC3 promotes transcriptome-wide activation of nonsense-mediated decay by the exon junction complex

2019 ◽  
Author(s):  
Jennifer V. Gerbracht ◽  
Volker Boehm ◽  
Thiago Britto-Borges ◽  
Sebastian Kallabis ◽  
Janica L. Wiederstein ◽  
...  
Keyword(s):  
Exon Junction Complex ◽  
Core Component ◽  
Mrna Isoforms ◽  
Nonsense Mediated Decay ◽  
Exon Junction ◽  
Endonucleolytic Cleavage ◽  
Core Proteins ◽  
Messenger Ribonucleoprotein ◽  
Cytoplasmic Processes

AbstractThe exon junction complex (EJC) is an essential constituent and regulator of spliced messenger ribonucleoprotein particles (mRNPs) in metazoans. As a core component of the EJC, CASC3 was described to be pivotal for EJC-dependent nuclear and cytoplasmic processes. However, recent evidence suggests that CASC3 functions differently from other EJC core proteins. Here, we have established human CASC3 knockout cell lines to elucidate the cellular role of CASC3. In the knockout cells, overall EJC composition and EJC-dependent splicing are unchanged. A transcriptome-wide analysis reveals that hundreds of mRNA isoforms targeted by nonsense-mediated decay (NMD) are upregulated. Mechanistically, recruiting CASC3 to reporter mRNAs by direct tethering or via binding to the EJC stimulates mRNA decay and endonucleolytic cleavage at the termination codon. Building on existing EJC-NMD models, we propose that CASC3 equips the EJC with the ability to communicate with the NMD machinery in the cytoplasm. Collectively, our results characterize CASC3 as a peripheral EJC protein that tailors the transcriptome by promoting the degradation of EJC-dependent NMD substrates.

scholarly journals A Haploid Genetic Screening Method for Proteins Influencing Mammalian Nonsense-Mediated mRNA Decay Activity

2018 ◽  
Author(s):  
Maximilian W. Popp ◽  
Lynne E. Maquat
Keyword(s):  
Genetic Screening ◽  
Mammalian Cells ◽  
Mrna Decay ◽  
Fluorescent Proteins ◽  
Screening Method ◽  
Transcript Abundance ◽  
Exon Junction Complex ◽  
Exon Junction ◽  
Nonsense Mediated Mrna Decay

AbstractDespite a long appreciation for the role of nonsense-mediated mRNA decay (NMD) in the destruction of faulty, disease-causing mRNAs, as well as its role in the maintenance of normal, endogenous transcript abundance, systematic unbiased methods for uncovering modifiers of NMD activity in mammalian cells remain scant. Here we present and validate a haploid genetic screening method for identifying proteins and processes that stimulate NMD activity involving a 3′-untranslated region exon-junction complex. This reporterbased screening method can be adapted for interrogating other pathways whose output can be measured by the intracellular production of fluorescent proteins.

Roles of the exon junction complex components in the central nervous system: a mini review

2018 ◽  
Vol 29 (8) ◽  
pp. 817-824 ◽  
Author(s):  
Katarzyna Bartkowska ◽  
Beata Tepper ◽  
Kris Turlejski ◽  
Ruzanna L. Djavadian
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Protein Translation ◽  
Adult Brain ◽  
Initiation Factor ◽  
Exon Junction Complex ◽  
Exon Junction ◽  
Core Proteins ◽  
Zygote Development ◽  
The Central Nervous System

Abstract The exon junction complex (EJC) consists of four core proteins: Magoh, RNA-binding motif 8A (Rbm8a, also known as Y14), eukaryotic initiation factor 4A3 (eIF4A3, also known as DDX48), and metastatic lymph node 51 (MLN51, also known as Casc3 or Barentsz), which are involved in the regulation of many processes occurring between gene transcription and protein translation. Its main role is to assemble into spliceosomes at the exon-exon junction of mRNA during splicing. It is, therefore, a range of functions concerning post-splicing events such as mRNA translocation, translation, and nonsense-mediated mRNA decay (NMD). Apart from this, proteins of the EJC control the splicing of specific pre-mRNAs, for example, splicing of the mapk transcript. Recent studies support essential functions of EJC proteins in oocytes and, after fertilization, in all stages of zygote development, as well as the growth of the embryo, including the development of the nervous system. During the development of the central nervous system (CNS), the EJC controls mitosis, regulating both symmetric and asymmetric cell divisions. Reduced levels of EJC components cause microcephaly. In the adult brain, Y14 and eIF4A3 appear to be involved in synaptic plasticity and in learning and memory. In this review, we focus on the involvement of EJC components in brain development and its functioning under normal conditions.

Sign in / Sign up

Export Citation Format

Share Document