Regulated and quality-control mRNA turnover pathways in eukaryotes

2010 ◽  
Vol 38 (6) ◽  
pp. 1506-1510 ◽  
Author(s):  
Boris Reznik ◽  
Jens Lykke-Andersen
Keyword(s):  
Quality Control ◽  
Rna Processing ◽  
Rna Localization ◽  
Rna Degradation ◽  
Eukaryotic Cells ◽  
Mrna Turnover ◽  
Surveillance Systems ◽  
Rna Turnover ◽  
Rna Surveillance ◽  
Multiple Levels

Gene expression can be regulated at multiple levels, including transcription, RNA processing, RNA localization, translation and, finally, RNA turnover. RNA degradation may occur at points along the processing pathway or during translation as it undergoes quality control by RNA surveillance systems. Alternatively, mRNAs may be subject to regulated degradation, often mediated by cis-encoded determinants in the mRNA sequence that, through the recruitment of trans factors, determine the fate of the mRNA. The aim of the present review is to highlight mechanisms of regulated and quality-control RNA degradation in eukaryotic cells, with an emphasis on mammals.

Comparison of the yeast and human nuclear exosome complexes

2012 ◽  
Vol 40 (4) ◽  
pp. 850-855 ◽  
Author(s):  
Katherine E. Sloan ◽  
Claudia Schneider ◽  
Nicholas J. Watkins
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Rna Processing ◽  
Eukaryotic Cells ◽  
Multiprotein Complex ◽  
Yeast Saccharomyces Cerevisiae ◽  
Rna Surveillance ◽  
Mature Transcript ◽  
Nuclear Exosome ◽  
And Function ◽  
Rna Maturation

Most RNAs in eukaryotic cells are produced as precursors that undergo processing at the 3′ and/or 5′ end to generate the mature transcript. In addition, many transcripts are degraded not only as part of normal recycling, but also when recognized as aberrant by the RNA surveillance machinery. The exosome, a conserved multiprotein complex containing two nucleases, is involved in both the 3′ processing and the turnover of many RNAs in the cell. A series of factors, including the TRAMP (Trf4–Air2–Mtr4 polyadenylation) complex, Mpp6 and Rrp47, help to define the targets to be processed and/or degraded and assist in exosome function. The majority of the data on the exosome and RNA maturation/decay have been derived from work performed in the yeast Saccharomyces cerevisiae. In the present paper, we provide an overview of the exosome and its role in RNA processing/degradation and discuss important new insights into exosome composition and function in human cells.

scholarly journals Mechanisms and Regulation of Nonsense-Mediated mRNA Decay and Nonsense-Associated Altered Splicing in Lymphoid Cells

2020 ◽  
Author(s):  
Jean-Marie Lambert ◽  
Mohamad Omar Ashi ◽  
Nivine Srour ◽  
Laurent Delpy ◽  
Jérôme Saulière
Keyword(s):  
Quality Control ◽  
Mrna Decay ◽  
Dominant Negative ◽  
Lymphoid Cells ◽  
Surveillance Systems ◽  
Rna Surveillance ◽  
Accelerated Degradation ◽  
Premature Termination Codons ◽  
Rna Quality Control ◽  
Nonsense Mediated Mrna Decay

The presence of premature termination codons (PTCs) in transcripts is dangerous for the cell as they encode potentially deleterious truncated proteins that can act with dominant-negative or gain-of-function effects. To avoid synthesis of these shortened polypeptides, several RNA surveillance systems can be activated to decrease the level of PTC-containing mRNAs. Nonsense-mediated mRNA decay (NMD) ensures an accelerated degradation of mRNAs harboring PTCs by using several key NMD factors such as up-frameshift (UPF) proteins. Another pathway called nonsense-associated altered splicing (NAS) upregulates transcripts that have skipped disturbing PTCs by alternative splicing. Therefore, these RNA quality control processes eliminate abnormal PTC-containing mRNAs from the cells by using positive and negative responses. In this review, we will describe the general mechanisms of NMD and NAS and their respective involvement in the decay of aberrant immunoglobulin and TCR transcripts in lymphoid cells.

scholarly journals Mechanisms and Regulation of Nonsense-Mediated mRNA Decay and Nonsense-Associated Altered Splicing in Lymphocytes

2020 ◽  
Vol 21 (4) ◽  
pp. 1335 ◽  
Author(s):  
Jean-Marie Lambert ◽  
Mohamad Omar Ashi ◽  
Nivine Srour ◽  
Laurent Delpy ◽  
Jérôme Saulière
Keyword(s):  
Quality Control ◽  
Alternative Splicing ◽  
Mrna Decay ◽  
Dominant Negative ◽  
Surveillance Systems ◽  
Rna Surveillance ◽  
Accelerated Degradation ◽  
Premature Termination Codons ◽  
Rna Quality Control ◽  
Nonsense Mediated Mrna Decay

The presence of premature termination codons (PTCs) in transcripts is dangerous for the cell as they encode potentially deleterious truncated proteins that can act with dominant-negative or gain-of-function effects. To avoid the synthesis of these shortened polypeptides, several RNA surveillance systems can be activated to decrease the level of PTC-containing mRNAs. Nonsense-mediated mRNA decay (NMD) ensures an accelerated degradation of mRNAs harboring PTCs by using several key NMD factors such as up-frameshift (UPF) proteins. Another pathway called nonsense-associated altered splicing (NAS) upregulates transcripts that have skipped disturbing PTCs by alternative splicing. Thus, these RNA quality control processes eliminate abnormal PTC-containing mRNAs from the cells by using positive and negative responses. In this review, we describe the general mechanisms of NMD and NAS and their respective involvement in the decay of aberrant immunoglobulin and TCR transcripts in lymphocytes.

scholarly journals A shape-shifting nuclease unravels structured RNA

2021 ◽  
Author(s):  
Katarina Meze ◽  
Armend Axhemi ◽  
Dennis R Thomas ◽  
Ahmet Doymaz ◽  
Leemor Joshua-Tor
Keyword(s):  
Gene Expression ◽  
Rna Processing ◽  
Cold Shock ◽  
Substrate Recognition ◽  
Critical Role ◽  
Rna Degradation ◽  
Rna Turnover ◽  
Linker Region ◽  
Conformational Plasticity ◽  
Gene Expression Levels

RNA turnover pathways ensure appropriate gene expression levels by eliminating unwanted transcripts that may otherwise interfere with cellular programs. The enzyme Dis3-like protein 2 (Dis3L2) is a 3′-5′ exoribonuclease that, through its RNA turnover activity, plays a critical role in human development1. Dis3L2 can independently degrade structured substrates and its targets include many coding and non-coding 3′-uridylated RNAs1-5. While the basis for Dis3L2 substrate recognition has been well-characterized6, the mechanism of structured RNA degradation by this family of enzymes is unknown. We characterized the discrete steps of the degradation cycle by determining electron cryo-microscopy structures representing snapshots along the RNA turnover pathway and measuring kinetic parameters for single-stranded (ss) and double-stranded (ds) RNA processing. We discovered a dramatic conformational change that is triggered by the dsRNA, involving repositioning of two cold shock domains by 70 Å. This movement exposes a trihelix-linker region, which acts as a wedge to separate the two RNA strands. Furthermore, we show that the trihelix linker is critical for dsRNA, but not ssRNA, degradation. These findings reveal the conformational plasticity of this enzyme, and detail a novel mechanism of structured RNA degradation.

scholarly journals Cooperativity between the Ribosome-Associated Chaperone Ssb/RAC and the Ubiquitin Ligase Ltn1 in Ubiquitination of Nascent Polypeptides

2020 ◽  
Vol 21 (18) ◽  
pp. 6815
Author(s):  
Arnab Ghosh ◽  
Natalia Shcherbik
Keyword(s):  
Quality Control ◽  
Ubiquitin Ligase ◽  
Protein Quality ◽  
Eukaryotic Cells ◽  
Surveillance Systems ◽  
Ribosomal Subunits ◽  
Proteotoxic Stress ◽  
Nascent Chain ◽  
Quantitative Western Blot

Eukaryotic cells have evolved multiple mechanisms to detect and eliminate aberrant polypeptides. Co-translational protein surveillance systems play an important role in these mechanisms. These systems include ribosome-associated protein quality control (RQC) that detects aberrant nascent chains stalled on ribosomes and promotes their ubiquitination and degradation by the proteasome, and ribosome-associated chaperone Ssb/RAC, which ensures correct nascent chain folding. Despite the known function of RQC and Ssb/ribosome-associated complex (RAC) in monitoring the quality of newly generated polypeptides, whether they cooperate during initial stages of protein synthesis remains unexplored. Here, we provide evidence that Ssb/RAC and the ubiquitin ligase Ltn1, the major component of RQC, display genetic and functional cooperativity. Overexpression of Ltn1 rescues growth suppression of the yeast strain-bearing deletions of SSB genes during proteotoxic stress. Moreover, Ssb/RAC promotes Ltn1-dependent ubiquitination of nascent chains associated with 80S ribosomal particles but not with translating ribosomes. Consistent with this finding, quantitative western blot analysis revealed lower levels of Ltn1 associated with 80S ribosomes and with free 60S ribosomal subunits in the absence of Ssb/RAC. We propose a mechanism in which Ssb/RAC facilitates recruitment of Ltn1 to ribosomes, likely by detecting aberrations in nascent chains and leading to their ubiquitination and degradation.

scholarly journals Is there quality control of localized mRNAs?

2014 ◽  
Vol 204 (6) ◽  
pp. 863-868 ◽  
Author(s):  
Robert Walters ◽  
Roy Parker
Keyword(s):  
Quality Control ◽  
Mrna Localization ◽  
Mrna Degradation ◽  
Eukaryotic Cells ◽  
Mrna Turnover ◽  
Local Production ◽  
Translation Repression ◽  
Additional Layer ◽  
In Cells

In eukaryotic cells many mRNAs are localized to specific regions of the cytosol, thereby allowing the local production of proteins. The process of mRNA localization can be coordinated with mRNA turnover, which can also be spatially controlled to increase the degree of mRNA localization. The coordination of mRNA localization, translation repression during transport, and mRNA degradation suggests the hypothesis that an additional layer of mRNA quality control exists in cells to degrade mRNAs that fail to be appropriately localized.

scholarly journals COVID-19 Brings Data Equity Challenges to the Fore

2021 ◽  
Author(s):  
H.V. Jagadish ◽  
Julia Stoyanovich ◽  
Bill Howe
Keyword(s):  
Quality Control ◽  
Government Policy ◽  
Data Driven ◽  
Contact Tracing ◽  
Control Mechanisms ◽  
Sources Of Information ◽  
Decision Systems ◽  
Physical Resources ◽  
Multiple Levels ◽  
Data Driven Decisions

The COVID-19 pandemic is compelling us to make crucial data-driven decisions quickly, bringing together diverse and unreliable sources of information without the usual quality control mechanisms we may employ. These decisions are consequential at multiple levels: they can inform local, state and national government policy, be used to schedule access to physical resources such as elevators and workspaces within an organization, and inform contact tracing and quarantine actions for individuals. In all these cases, significant inequities are likely to arise, and to be propagated and reinforced by data-driven decision systems. In this article, we propose a framework, called FIDES, for surfacing and reasoning about data equity in these systems.

c-myc RNA degradation in growing and differentiating cells: possible alternate pathways

1989 ◽  
Vol 9 (1) ◽  
pp. 288-295
Author(s):  
S G Swartwout ◽  
A J Kinniburgh
Keyword(s):  
Actinomycin D ◽  
Rna Degradation ◽  
Transcriptional Elongation ◽  
Rna Turnover ◽  
Rapid Degradation ◽  
Polyadenylated Rna ◽  
Myc Gene ◽  
Fail Safe ◽  
Kinetics Of ◽  
In Cells

Transcripts of the proto-oncogene c-myc are composed of a rapidly degraded polyadenylated RNA species and an apparently much more stable, nonadenylated RNA species. In this report, the extended kinetics of c-myc RNA turnover have been examined in rapidly growing cells and in cells induced to differentiate. When transcription was blocked with actinomycin D in rapidly growing cells, poly(A)+ c-myc was rapidly degraded (t1/2 = 12 min). c-myc RNA lacking poly(A) initially remained at or near control levels; however, after 80 to 90 min it was degraded with kinetics similar to those of poly(A)+ c-myc RNA. These bizarre kinetics are due to the deadenylation of poly(A)+ c-myc RNA to form poly(A)- c-myc, thereby initially maintaining the poly(A)- c-myc RNA pool when transcription is blocked. In contrast to growing cells, cells induced to differentiate degraded both poly(A)+ and poly(A)- c-myc RNA rapidly. The rapid disappearance of both RNA species in differentiating cells suggests that a large proportion of the poly(A)+ c-myc RNA was directly degraded without first being converted to poly(A)- c-myc RNA. Others have shown that transcriptional elongation of the c-myc gene is rapidly blocked in differentiating cells. We therefore hypothesize that in differentiating cells a direct, rapid degradation of poly(A)+ c-myc RNA may act as a backup or fail-safe system to ensure that c-myc protein is not synthesized. This tandem system of c-myc turnoff may also make cells more refractory to mutations which activate constitutive c-myc expression.

scholarly journals Crystal structure of the ribonuclease-P-protein subunit from Staphylococcus aureus

2018 ◽  
Vol 74 (10) ◽  
pp. 632-637
Author(s):  
Lisha Ha ◽  
Jennifer Colquhoun ◽  
Nicholas Noinaj ◽  
Chittaranjan Das ◽  
Paul M. Dunman ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Staphylococcus Aureus ◽  
Rna Processing ◽  
Bacterial Species ◽  
Rna Degradation ◽  
Ribonuclease P ◽  
Protein Subunit ◽  
Aromatic Residues ◽  
Cellular Processes ◽  
P Protein

Staphylococcus aureus ribonuclease-P-protein subunit (RnpA) is a promising antimicrobial target that is a key protein component for two essential cellular processes, RNA degradation and transfer-RNA (tRNA) maturation. The first crystal structure of RnpA from the pathogenic bacterial species, S. aureus, is reported at 2.0 Å resolution. The structure presented maintains key similarities with previously reported RnpA structures from bacteria and archaea, including the highly conserved RNR-box region and aromatic residues in the precursor-tRNA 5′-leader-binding domain. This structure will be instrumental in the pursuit of structure-based designed inhibitors targeting RnpA-mediated RNA processing as a novel therapeutic approach for treating S. aureus infections.

scholarly journals A meiotic gene regulatory cascade driven by alternative fates for newly synthesized transcripts

2011 ◽  
Vol 22 (1) ◽  
pp. 66-77 ◽  
Author(s):  
Nicole Cremona ◽  
Kristine Potter ◽  
Jo Ann Wise
Keyword(s):  
Fission Yeast ◽  
Rna Processing ◽  
Yeast Cells ◽  
Forkhead Transcription Factor ◽  
Rna Surveillance ◽  
Regulatory Cascade ◽  
Show Evidence ◽  
Gene Regulatory ◽  
Rna Accumulation ◽  
Temporal Profiles

To determine the relative importance of transcriptional regulation versus RNA processing and turnover during the transition from proliferation to meiotic differentiation in the fission yeast Schizosaccharomyces pombe, we analyzed temporal profiles and effects of RNA surveillance factor mutants on expression of 32 meiotic genes. A comparison of nascent transcription with steady-state RNA accumulation reveals that the vast majority of these genes show a lag between maximal RNA synthesis and peak RNA accumulation. During meiosis, total RNA levels parallel 3′ processing, which occurs in multiple, temporally distinct waves that peak from 3 to 6 h after meiotic induction. Most early genes and one middle gene, mei4, share a regulatory mechanism in which a specialized RNA surveillance factor targets newly synthesized transcripts for destruction. Mei4p, a member of the forkhead transcription factor family, in turn regulates a host of downstream genes. Remarkably, a spike in transcription is observed for less than one-third of the genes surveyed, and even these show evidence of RNA-level regulation. In aggregate, our findings lead us to propose that a regulatory cascade driven by changes in processing and stability of newly synthesized transcripts operates alongside the well-known transcriptional cascade as fission yeast cells enter meiosis.

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