scholarly journals NONU-1 encodes a conserved endonuclease required for mRNA translation surveillance

2019 ◽  
Author(s):  
Marissa L. Glover ◽  
A. Max. Burroughs ◽  
Thea A. Egelhofer ◽  
Makena N. Pule ◽  
L. Aravind ◽  
...  
Keyword(s):  
Mrna Decay ◽  
Domain Architecture ◽  
Mrna Translation ◽  
Mrna Levels ◽  
Mechanistic Studies ◽  
C Elegans ◽  
Endonucleolytic Cleavage ◽  
Nonstop Mrna Decay ◽  
Unknown Factor ◽  
Cellular Translation

ABSTRACTCellular translation surveillance rescues ribosomes that stall on problematic mRNAs. During translation surveillance, endonucleolytic cleavage of the problematic mRNA is a critical step in rescuing stalled ribosomes. However, the nuclease(s) responsible remain unknown. Here we identify NONU-1 as a novel endoribonuclease required for translation surveillance pathways including No-Go and Nonstop mRNA Decay. We show that: (1) NONU-1 reduces Nonstop and No-Go mRNA levels; (2) NONU-1 contains an Smr RNase domain required for mRNA decay and with properties similar to the unknown endonuclease; and (3) the domain architecture and catalytic residues of NONU-1 are conserved throughout metazoans and eukaryotes, respectively. We extend our results inC. elegansto homologous factors inS. cerevisiae, showing conservation of function of the NONU-1 protein across billions of years of evolution. Our work establishes the identity of a previously unknown factor critical to translation surveillance and will inform mechanistic studies at the intersection of translation and mRNA decay.

scholarly journals Ribosomal ubiquitination facilitates mRNA cleavage and ribosome rescue during No-Go and Nonstop mRNA Decay

2021 ◽  
Author(s):  
Parissa C. Monem ◽  
Audrey L. Piatt ◽  
Nitin Vidyasagar ◽  
Marissa L. Glover ◽  
Thea A. Egelhofer ◽  
...  
Keyword(s):  
Ribosomal Proteins ◽  
Mrna Decay ◽  
Critical Role ◽  
Mrna Degradation ◽  
C Elegans ◽  
N Terminus ◽  
Nonstop Mrna Decay ◽  
Cellular Machinery ◽  
Translation Signals

During translational surveillance, ribosomes play a critical role in detecting problematic mRNAs and signaling cellular machinery to repress the offending messages. Prior work has shown that problematic mRNAs identified by two surveillance pathways (Nonstop and No-Go mRNA Decay) are detected by ribosome collisions and subsequent ribosomal ubiquitination, yet how ribosomal ubiquitination leads to repression has remained unclear. Here, we deploy C. elegans to unravel the series of coordinated events during Nonstop and No-Go mRNA Decay. We probe the metazoan SKI RNA helicase complex to uncover functionally significant residues and reveal divergence of the SKI-exosome interface. We define a functional requirement for ubiquitination on at least two ribosomal proteins during No-Go mRNA Decay, and illustrate how ubiquitination recruits the endonuclease NONU-1 via CUE domains and the ribosome rescue factor HBS-1 via its poorly characterized N-terminus. Our molecular characterization (1) underscores the importance of ribosomal ubiquitination in mRNA degradation, (2) shows similar and distinct genetic dependencies of factors in Nonstop and No-Go mRNA Decay, and (3) uncovers a conspicuous absence of distinct ribosomal stalls at No-Go mRNA Decay substrates. Our work demonstrates mechanisms by which translation signals to effectors of co-translational mRNA repression and has implications for the study of translation and ribosomal species in vivo.

Mechanical activity in heart regulates translation of α-myosin heavy chain mRNA but not its localization

1999 ◽  
Vol 276 (6) ◽  
pp. H2013-H2019 ◽  
Author(s):  
Gordana Nikcevic ◽  
Maria C. Heidkamp ◽  
Merja Perhonen ◽  
Brenda Russell
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Mrna Translation ◽  
Neonatal Rat ◽  
Mechanical Activity ◽  
Mrna Levels ◽  
Rat Cardiomyocytes ◽  
Significant Difference ◽  
Polysomal Fraction ◽  
Mechanical Transduction

Mechanical inactivity depresses protein expression in cardiac muscle tissue and results in atrophy. We explore the mechanical transduction mechanism in spontaneously beating neonatal rat cardiomyocytes expressing the α-myosin heavy chain (α-MyHC) isoform by interfering with cross-bridge function [2,3-butanedione monoxime (BDM), 7.5 mM] without affecting cell calcium. The polysome content and α-MyHC mRNA levels in fractions from a sucrose gradient were analyzed. BDM treatment blocked translation at initiation (162 ± 12% in the nonpolysomal RNA fraction and 43 ± 6% in the polysomal fraction, relative to control as 100%; P < 0.05). There was an increase in α-MyHC mRNA from the nonpolysomal fraction (120.5 ± 7.7%; P < 0.05 compared with control) with no significant change in the heavy polysomes. In situ hybridization of α-MyHC mRNA was used to estimate message abundance as a function of the distance from the nucleus. The mRNA was dispersed through the cytoplasm in spontaneously beating cells as well as in BDM-treated cells (no significant difference). We conclude that direct inhibition of contractile machinery, but not calcium, regulates initiation of α-MyHC mRNA translation. However, calcium, not pure mechanical signals, appears to be important for message localization.

scholarly journals tmRNA determinants required for facilitating nonstop mRNA decay

RNA ◽  
2006 ◽  
Vol 12 (12) ◽  
pp. 2187-2198 ◽  
Author(s):  
P. Mehta ◽  
J. Richards ◽  
A. W. Karzai
Keyword(s):  
Mrna Decay ◽  
Nonstop Mrna Decay

scholarly journals Targeted inhibition of eIF4A suppresses B-cell receptor-induced translation and expression of MYC and MCL1 in chronic lymphocytic leukemia cells

2021 ◽  
Author(s):  
Sarah Wilmore ◽  
Karly-Rai Rogers-Broadway ◽  
Joe Taylor ◽  
Elizabeth Lemm ◽  
Rachel Fell ◽  
...  
Keyword(s):  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Mrna Translation ◽  
Cell Receptor ◽  
Memory B Cells ◽  
B Cell Receptor ◽  
Lymphocytic Leukemia ◽  
Mrna Levels ◽  
Mrna Stabilization

AbstractSignaling via the B-cell receptor (BCR) is a key driver and therapeutic target in chronic lymphocytic leukemia (CLL). BCR stimulation of CLL cells induces expression of eIF4A, an initiation factor important for translation of multiple oncoproteins, and reduces expression of PDCD4, a natural inhibitor of eIF4A, suggesting that eIF4A may be a critical nexus controlling protein expression downstream of the BCR in these cells. We, therefore, investigated the effect of eIF4A inhibitors (eIF4Ai) on BCR-induced responses. We demonstrated that eIF4Ai (silvestrol and rocaglamide A) reduced anti-IgM-induced global mRNA translation in CLL cells and also inhibited accumulation of MYC and MCL1, key drivers of proliferation and survival, respectively, without effects on upstream signaling responses (ERK1/2 and AKT phosphorylation). Analysis of normal naïve and non-switched memory B cells, likely counterparts of the two main subsets of CLL, demonstrated that basal RNA translation was higher in memory B cells, but was similarly increased and susceptible to eIF4Ai-mediated inhibition in both. We probed the fate of MYC mRNA in eIF4Ai-treated CLL cells and found that eIF4Ai caused a profound accumulation of MYC mRNA in anti-IgM treated cells. This was mediated by MYC mRNA stabilization and was not observed for MCL1 mRNA. Following drug wash-out, MYC mRNA levels declined but without substantial MYC protein accumulation, indicating that stabilized MYC mRNA remained blocked from translation. In conclusion, BCR-induced regulation of eIF4A may be a critical signal-dependent nexus for therapeutic attack in CLL and other B-cell malignancies, especially those dependent on MYC and/or MCL1.

Codon replacement in the PGK1 gene of Saccharomyces cerevisiae: experimental approach to study the role of biased codon usage in gene expression

1987 ◽  
Vol 7 (8) ◽  
pp. 2914-2924
Author(s):  
A Hoekema ◽  
R A Kastelein ◽  
M Vasser ◽  
H A de Boer
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Steady State ◽  
Codon Usage ◽  
Experimental Approach ◽  
Mrna Translation ◽  
Yeast Cells ◽  
Expression Level ◽  
Start Codon ◽  
Mrna Levels

The coding sequences of genes in the yeast Saccharomyces cerevisiae show a preference for 25 of the 61 possible coding triplets. The degree of this biased codon usage in each gene is positively correlated to its expression level. Highly expressed genes use these 25 major codons almost exclusively. As an experimental approach to studying biased codon usage and its possible role in modulating gene expression, systematic codon replacements were carried out in the highly expressed PGK1 gene. The expression of phosphoglycerate kinase (PGK) was studied both on a high-copy-number plasmid and as a single copy gene integrated into the chromosome. Replacing an increasing number (up to 39% of all codons) of major codons with synonymous minor ones at the 5' end of the coding sequence caused a dramatic decline of the expression level. The PGK protein levels dropped 10-fold. The steady-state mRNA levels also declined, but to a lesser extent (threefold). Our data indicate that this reduction in mRNA levels was due to destabilization caused by impaired translation elongation at the minor codons. By preventing translation of the PGK mRNAs by the introduction of a stop codon 3' and adjacent to the start codon, the steady-state mRNA levels decreased dramatically. We conclude that efficient mRNA translation is required for maintaining mRNA stability in S. cerevisiae. These findings have important implications for the study of the expression of heterologous genes in yeast cells.

Stage-specific patterns of collagen gene expression during development of Caenorhabditis elegans

1985 ◽  
Vol 5 (2) ◽  
pp. 363-372
Author(s):  
G N Cox ◽  
D Hirsh
Keyword(s):  
Caenorhabditis Elegans ◽  
Protein Composition ◽  
Large Family ◽  
Major Protein ◽  
Mrna Levels ◽  
Mrna Accumulation ◽  
C Elegans ◽  
Collagen Protein ◽  
Protein Components ◽  
Collagen Genes

Collagens are the major protein components of the Caenorhabditis elegans cuticle and are encoded by a large family of 40 to 150 closely related but nonidentical genes. We have determined temporal patterns of mRNA accumulation for a large number of collagen genes by screening recombinant phages and plasmids containing cloned collagen genes under high stringency conditions with 32P-labeled cDNA preparations specific for eggs or three postembryonic molts. We find that collagen mRNA levels are regulated both temporally and quantitatively during C. elegans development. Most genes studied exhibit one of four patterns of mRNA accumulation which correlate with changes in cuticle morphology and collagen protein composition during development. Our results suggest that, in general, there is a progressive activation of new collagen genes during normal development.

scholarly journals Eukaryotic initiation factor EIF-3.G augments mRNA translation efficiency to regulate neuronal activity

2021 ◽  
Author(s):  
Stephen M Blazie ◽  
Seika Takayanagi-Kiya ◽  
Katherine A McCulloch ◽  
Yishi Jin
Keyword(s):  
Rna Binding ◽  
Mrna Translation ◽  
Initiation Factor ◽  
Translation Efficiency ◽  
Dependent Manner ◽  
Control Activity ◽  
C Elegans ◽  
Protein Levels ◽  
Neuronal Protein

AbstractThe translation initiation complex eIF3 imparts specialized functions to regulate protein expression. However, understanding of eIF3 activities in neurons remains limited despite widespread dysregulation of eIF3 subunits in neurological disorders. Here, we report a selective role of theC. elegansRNA-binding subunit EIF-3.G in shaping the neuronal protein landscape. We identify a missense mutation in the conserved Zinc-Finger (ZF) of EIF-3.G that acts in a gain-of-function manner to dampen neuronal hyperexcitation. Using neuron type-specific seCLIP, we systematically mapped EIF-3.G-mRNA interactions and identified EIF-3.G occupancy on GC-rich 5′UTRs of a select set of mRNAs enriched in activity-dependent functions. We demonstrate that the ZF mutation in EIF-3.G alters translation in a 5′UTR dependent manner. Our study reveals anin vivomechanism for eIF3 in governing neuronal protein levels to control activity states and offers insights into how eIF3 dysregulation contributes to neuronal disorders.

scholarly journals Satellite cell expansion is mediated by P-eIF2α dependent Tacc3 translation

Development ◽  
2020 ◽  
pp. dev.194480
Author(s):  
Ryo Fujita ◽  
Solène Jamet ◽  
Graham Lean ◽  
Harry Chun Man Cheng ◽  
Steven Hébert ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Satellite Cells ◽  
Translational Control ◽  
Ex Vivo ◽  
Adult Stem Cell ◽  
Mrna Translation ◽  
Spindle Pole ◽  
Mrna Levels ◽  
Self Renewal ◽  
Control Of Gene Expression

Translational control of gene expression is an important regulator of adult stem cell quiescence, activation and self-renewal. In skeletal muscle, quiescent satellite cells maintain low levels of protein synthesis, mediated in part through the phosphorylation of eIF2α (P-eIF2α). Pharmacological inhibition of the eIF2α phosphatase with the small molecule sal003 maintains P-eIF2α and permits the expansion of satellite cells ex vivo. Paradoxically, P-eIF2α also increases the translation of specific mRNAs, which is mediated by P-eIF2α dependent readthrough of inhibitory upstream open reading frames (uORFs). Here, we ask whether P-eIF2α dependent mRNA translation enables expansion of satellite cells. Using transcriptomic and proteomic analyses, we show a number of genes associated with the assembly of the spindle pole to be upregulated at the level of protein, without corresponding change in mRNA levels, in satellite cells expanded in the presence of sal003. We show that uORFs in the 5'UTR of mRNA for the mitotic spindle stability gene Tacc3 direct P-eIF2α dependent translation. Satellite cells deficient for TACC3 exhibit defects in expansion, self-renewal and regeneration of skeletal muscle.

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