scholarly journals The viral protein NSP1 acts as a ribosome gatekeeper for shutting down host translation and fostering SARS-CoV-2 translation

2020 ◽  
Author(s):  
Antonin Tidu ◽  
Aurélie Janvier ◽  
Laure Schaeffer ◽  
Piotr Sosnowski ◽  
Lauriane Kuhn ◽  
...  
Keyword(s):  
Late Phase ◽  
Apical Part ◽  
Therapeutic Strategies ◽  
Structural Proteins ◽  
Viral Translation ◽  
Genomic Rnas ◽  
Translation Inhibition ◽  
Cellular Translation ◽  
Rna Hairpin ◽  
Late Stages

AbstractSARS-CoV-2 coronavirus is responsible for Covid-19 pandemic. In the early phase of infection, the single-strand positive RNA genome is translated into non-structural proteins (NSP). One of the first proteins produced during viral infection, NSP1, binds to the host ribosome and blocks the mRNA entry channel. This triggers translation inhibition of cellular translation. In spite of the presence of NSP1 on the ribosome, viral translation proceeds however. The molecular mechanism of the so-called viral evasion to NSP1 inhibition remains elusive. Here, we confirm that viral translation is maintained in the presence of NSP1. The evasion to NSP1-inhibition is mediated by the cis-acting RNA hairpin SL1 in the 5’UTR of SARS-CoV-2. NSP1-evasion can be transferred on a reporter transcript by SL1 transplantation. The apical part of SL1 is only required for viral translation. We show that NSP1 remains bound on the ribosome during viral translation. We suggest that the interaction between NSP1 and SL1 frees the mRNA accommodation channel while maintaining NSP1 bound to the ribosome. Thus, NSP1 acts as a ribosome gatekeeper, shutting down host translation or fostering SARS-CoV-2 translation depending on the presence of the SL1 5’UTR hairpin. SL1 is also present and necessary for translation of sub-genomic RNAs in the late phase of the infectious program. Consequently, therapeutic strategies targeting SL1 should affect viral translation at early and late stages of infection. Therefore, SL1 might be seen as a genuine ‘Achille heel’ of the virus.

scholarly journals Viral Translation Is Coupled to Transcription in Sindbis Virus-Infected Cells

2007 ◽  
Vol 81 (13) ◽  
pp. 7061-7068 ◽  
Author(s):  
Miguel A. Sanz ◽  
Alfredo Castelló ◽  
Luis Carrasco
Keyword(s):  
Sindbis Virus ◽  
Late Phase ◽  
Mrna Translation ◽  
Encephalomyocarditis Virus ◽  
Host Protein ◽  
Viral Mrnas ◽  
Viral Translation ◽  
Bhk Cells ◽  
Infected Cells

ABSTRACT During the late phase of Sindbis virus infection, the viral subgenomic mRNA is translated efficiently in BHK cells, whereas host protein synthesis is inhibited. However, transfection of in vitro-generated Sindbis virus subgenomic mRNA leads to efficient translation in uninfected BHK cells, whereas it is a poor substrate in infected cells. Therefore, the structure of the subgenomic mRNA itself is not sufficient to confer its translatability in infected cells. In this regard, translation of the subgenomic mRNA requires synthesis from the viral transcription machinery. The lack of translation of transfected viral mRNAs in infected cells is not due to their degradation nor is it a consequence of competition between viral transcripts and transfected mRNAs, because a replicon that cannot produce subgenomic mRNA also interferes with exogenous mRNA translation. Interestingly, subgenomic mRNA is translated more efficiently when it is transfected into uninfected cells than when it is transcribed from a transfected replicon. Finally, a similar behavior was observed for other RNA viruses, such as vesicular stomatitis virus and encephalomyocarditis virus. These findings support the notion that translation is coupled to transcription in cells infected with different animal viruses.

scholarly journals Critical Role for Arginine Methylation in Adenovirus-Infected Cells

2007 ◽  
Vol 81 (23) ◽  
pp. 13209-13217 ◽  
Author(s):  
Demetris C. Iacovides ◽  
Clodagh C. O'Shea ◽  
Juan Oses-Prieto ◽  
Alma Burlingame ◽  
Frank McCormick
Keyword(s):  
Amino Acids ◽  
Critical Role ◽  
Arginine Methylation ◽  
Structural Proteins ◽  
Adenovirus Infection ◽  
The Third ◽  
C Terminus ◽  
Arginine Residues ◽  
Infected Cells ◽  
Late Stages

ABSTRACT During the late stages of adenovirus infection, the 100K protein (100K) inhibits the translation of cellular messages in the cytoplasm and regulates hexon trimerization and assembly in the nucleus. However, it is not known how it switches between these two functions. Here we show that 100K is methylated on arginine residues at its C terminus during infection and that this region is necessary for binding PRMT1 methylase. Methylated 100K is exclusively nuclear. Mutation of the third RGG motif (amino acids 741 to 743) prevents localization to the nucleus during infection, suggesting that methylation of that sequence is important for 100K shuttling. Treatment of infected cells with methylation inhibitors inhibits expression of late structural proteins. These data suggest that arginine methylation of 100K is necessary for its localization to the nucleus and is a critical cellular function necessary for productive adenovirus infection.

scholarly journals Mechanisms of translation inhibition and suppression of Stress Granule formation by cisplatin

2021 ◽  
Author(s):  
Paulina Pietras ◽  
Anais Aulas ◽  
Marta M Fay ◽  
Marta Lesniczak ◽  
Shawn M Lyons ◽  
...  
Keyword(s):  
Multiple Roles ◽  
Poor Correlation ◽  
Tumor Cell Death ◽  
Granule Formation ◽  
Ribosomal Subunits ◽  
Translation Inhibition ◽  
Rna Granules ◽  
Dna And Rna ◽  
Cellular Translation ◽  
Dna And Rna Synthesis

Platinum-based antineoplastic drugs, such as cisplatin, are commonly used to induce tumor cell death. Cisplatin is believed to induce apoptosis as a result of cisplatin-DNA adducts that inhibit DNA and RNA synthesis. Although idea that DNA damage underlines anti-proliferative effects of cisplatin is dominant in cancer research, there is a poor correlation between the degree of the cell sensitivity to cisplatin and the extent of DNA platination. Here, we propose a novel mechanism of cisplatin-mediated cytotoxicity. We show that cisplatin suppresses formation of Stress Granules (SGs), pro-survival RNA granules with multiple roles in cellular metabolism. Mechanistically, cisplatin inhibits cellular translation to promote disassembly of polysomes and aggregation of ribosomal subunits. As SGs are in equilibrium with polysomes, cisplatin-induced shift towards ribosomal aggregation suppresses SG formation and promotes cellular death. Our data also explain nephrotoxic, neurotoxic and ototoxic effects of cisplatin treatment.

scholarly journals Genomic Variations in the Structural Proteins of SARS-CoV-2 and Their Deleterious Impact on Pathogenesis: A Comparative Genomics Approach

2021 ◽  
Vol 11 ◽  
Author(s):  
Taj Mohammad ◽  
Arunabh Choudhury ◽  
Insan Habib ◽  
Purva Asrani ◽  
Yash Mathur ◽  
...  
Keyword(s):  
Comparative Genomics ◽  
Therapeutic Strategies ◽  
Surface Glycoprotein ◽  
Structural Proteins ◽  
Therapeutic Approaches ◽  
Structural Variations ◽  
Main Protease ◽  
Functional Consequences ◽  
Comparative Genomics Analysis ◽  
Global Threat

A continual rise in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection causing coronavirus disease (COVID-19) has become a global threat. The main problem comes when SARS-CoV-2 gets mutated with the rising infection and becomes more lethal for humankind than ever. Mutations in the structural proteins of SARS-CoV-2, i.e., the spike surface glycoprotein (S), envelope (E), membrane (M) and nucleocapsid (N), and replication machinery enzymes, i.e., main protease (Mpro) and RNA-dependent RNA polymerase (RdRp) creating more complexities towards pathogenesis and the available COVID-19 therapeutic strategies. This study analyzes how a minimal variation in these enzymes, especially in S protein at the genomic/proteomic level, affects pathogenesis. The structural variations are discussed in light of the failure of small molecule development in COVID-19 therapeutic strategies. We have performed in-depth sequence- and structure-based analyses of these proteins to get deeper insights into the mechanism of pathogenesis, structure-function relationships, and development of modern therapeutic approaches. Structural and functional consequences of the selected mutations on these proteins and their association with SARS-CoV-2 virulency and human health are discussed in detail in the light of our comparative genomics analysis.

scholarly journals Translation control of Enterovirus A71 gene expression

2020 ◽  
Vol 27 (1) ◽  
Author(s):  
Ming-Chih Lai ◽  
Han-Hsiang Chen ◽  
Peng Xu ◽  
Robert Y. L. Wang
Keyword(s):  
Host Cell ◽  
Defense Mechanism ◽  
Internal Ribosomal Entry Site ◽  
Viral Rna ◽  
Translation Control ◽  
Entry Site ◽  
Viral Translation ◽  
Antiviral Responses ◽  
Enterovirus A71 ◽  
Cellular Translation

AbstractUpon EV-A71 infection of a host cell, EV-A71 RNA is translated into a viral polyprotein. Although EV-A71 can use the cellular translation machinery to produce viral proteins, unlike cellular translation, which is cap-dependent, the viral RNA genome of EV-A71 does not contain a 5′ cap and the translation of EV-A71 protein is cap-independent, which is mediated by the internal ribosomal entry site (IRES) located in the 5′ UTR of EV-A71 mRNA. Like many other eukaryotic viruses, EV-A71 manipulates the host cell translation devices, using an elegant RNA-centric strategy in infected cells. During viral translation, viral RNA plays an important role in controlling the stage of protein synthesis. In addition, due to the cellular defense mechanism, viral replication is limited by down-regulating translation. EV-A71 also utilizes protein factors in the host to overcome antiviral responses or even use them to promote viral translation rather than host cell translation. In this review, we provide an introduction to the known strategies for EV-A71 to exploit cellular translation mechanisms.

scholarly journals Suppression of Pain in the Late Phase of Chronic Trigeminal Neuropathic Pain Failed to Rescue the Decision-Making Deficits in Rats

2021 ◽  
Vol 22 (15) ◽  
pp. 7846
Author(s):  
Suresh Kanna Murugappan ◽  
Li Xie ◽  
Heung Yan Wong ◽  
Zafar Iqbal ◽  
Zhuogui Lei ◽  
...  
Keyword(s):  
Decision Making ◽  
Neuropathic Pain ◽  
Late Phase ◽  
Anterior Cingulate ◽  
Nerve Lesion ◽  
Chronic Neuropathic Pain ◽  
Functional Deficits ◽  
Trigeminal Neuropathic Pain ◽  
Neural Sensitization ◽  
Late Stages

Trigeminal neuropathic pain (TNP) led to vital cognitive functional deficits such as impaired decision-making abilities in a rat gambling task. Chronic TNP caused hypomyelination in the anterior cingulate cortex (ACC) associated with decreased synchronization between ACC spikes and basal lateral amygdala (BLA) theta oscillations. The aim of this study was to investigate the effect of pain suppression on cognitive impairment in the early or late phases of TNP. Blocking afferent signals with a tetrodotoxin (TTX)-ELVAX implanted immediately following nerve lesion suppressed the allodynia and rescued decision-making deficits. In contrast, the TTX used at a later phase could not suppress the allodynia nor rescue decision-making deficits. Intra-ACC administration of riluzole reduced the ACC neural sensitization but failed to restore ACC-BLA spike-field phase synchrony during the late stages of chronic neuropathic pain. Riluzole suppressed allodynia but failed to rescue the decision-making deficits during the late phase of TNP, suggesting that early pain relief is important for recovering from pain-related cognitive impairments. The functional disturbances in ACC neural circuitry may be relevant causes for the deficits in decision making in the chronic TNP state.

scholarly journals Mutational analysis indicates that abnormalities in rhizobial infection and subsequent plant cell and bacteroid differentiation in pea (Pisum sativum) nodules coincide with abnormal cytokinin responses and localization

2020 ◽  
Vol 125 (6) ◽  
pp. 905-923 ◽  
Author(s):  
Elena A Dolgikh ◽  
Pyotr G Kusakin ◽  
Anna B Kitaeva ◽  
Anna V Tsyganova ◽  
Anna N Kirienko ◽  
...  
Keyword(s):  
Pisum Sativum ◽  
Plant Cell ◽  
Mutational Analysis ◽  
Apical Part ◽  
Wild Type ◽  
Peripheral Tissues ◽  
Nod Factor ◽  
Pea Mutants ◽  
Genetic Constructs ◽  
Late Stages

Abstract Background and Aims Recent findings indicate that Nod factor signalling is tightly interconnected with phytohormonal regulation that affects the development of nodules. Since the mechanisms of this interaction are still far from understood, here the distribution of cytokinin and auxin in pea (Pisum sativum) nodules was investigated. In addition, the effect of certain mutations blocking rhizobial infection and subsequent plant cell and bacteroid differentiation on cytokinin distribution in nodules was analysed. Methods Patterns of cytokinin and auxin in pea nodules were profiled using both responsive genetic constructs and antibodies. Key Results In wild-type nodules, cytokinins were found in the meristem, infection zone and apical part of the nitrogen fixation zone, whereas auxin localization was restricted to the meristem and peripheral tissues. We found significantly altered cytokinin distribution in sym33 and sym40 pea mutants defective in IPD3/CYCLOPS and EFD transcription factors, respectively. In the sym33 mutants impaired in bacterial accommodation and subsequent nodule differentiation, cytokinin localization was mostly limited to the meristem. In addition, we found significantly decreased expression of LOG1 and A-type RR11 as well as KNOX3 and NIN genes in the sym33 mutants, which correlated with low cellular cytokinin levels. In the sym40 mutant, cytokinins were detected in the nodule infection zone but, in contrast to the wild type, they were absent in infection droplets. Conclusions In conclusion, our findings suggest that enhanced cytokinin accumulation during the late stages of symbiosis development may be associated with bacterial penetration into the plant cells and subsequent plant cell and bacteroid differentiation.

scholarly journals The Spore-Specific Alanine Racemase of Bacillus anthracis and Its Role in Suppressing Germination during Spore Development

2008 ◽  
Vol 191 (4) ◽  
pp. 1303-1310 ◽  
Author(s):  
Olga N. Chesnokova ◽  
Sylvia A. McPherson ◽  
Christopher T. Steichen ◽  
Charles L. Turnbough
Keyword(s):  
Bacillus Anthracis ◽  
Mother Cell ◽  
Basal Layer ◽  
Structural Proteins ◽  
Alanine Racemase ◽  
Spore Development ◽  
Germination Inhibitor ◽  
Atypical Localization ◽  
Late Stages ◽  
Premature Germination

ABSTRACT Spores of Bacillus anthracis are enclosed by an exosporium composed of a basal layer and an external hair-like nap. The nap is apparently formed by a single glycoprotein, while the basal layer contains many different structural proteins and several enzymes. One of the enzymes is Alr, an alanine racemase capable of converting the spore germinant l-alanine to the germination inhibitor d-alanine. Unlike other characterized exosporium proteins, Alr is nonuniformly distributed in the exosporium and might have a second spore location. In this study, we demonstrated that expression of the alr gene, which encodes Alr, is restricted to sporulating cells and that the bulk of alr transcription and Alr synthesis occurs during the late stages of sporulation. We also mapped two alr promoters that are differentially active during sporulation and might be involved in the atypical localization of Alr. Finally, we constructed a Δalr mutant of B. anthracis that lacks Alr and examined the properties of the spores produced by this strain. Mature Δalr spores germinate more efficiently in the presence of l-alanine, presumably because of their inability to convert exogenous l-alanine to d-alanine, but they respond normally to other germinants. Surprisingly, the production of mature spores by the Δalr mutant is defective because approximately one-half of the nascent spores germinate and lose their resistance properties before they are released from the mother cell. This phenotype suggests that an important function of Alr is to produce d-alanine during the late stages of sporulation to suppress premature germination of the developing spore.

scholarly journals Novel method for intrafollicular pressure measurements in the rat ovary: increased intrafollicular pressure after hCG stimulation

Reproduction ◽  
2001 ◽  
pp. 307-314 ◽  
Author(s):  
M Matousek ◽  
C Carati ◽  
B Gannon ◽  
M Brannstrom
Keyword(s):  
Late Phase ◽  
Mean Amplitude ◽  
Short Term ◽  
Pressure System ◽  
Follicular Size ◽  
Novel Method ◽  
Rat Ovary ◽  
The Mean ◽  
Late Stages ◽  
Ovulatory Process

The ovulatory process in the rat comprises a period of about 12-15 h, from the time of the preovulatory LH surge to follicular rupture and extrusion of the oocyte. Follicular rupture is most likely caused, at least in part, by decreased tensile strength at the follicular apex due to degradation of collagen fibres of the extracellular matrix. It has been debated whether changes in intrafollicular pressure occur during the ovulatory process and whether such changes facilitate rupture of the follicle. In the present study, rats were primed with equine chorionic gonadotrophin (eCG, 10 iu) followed by hCG (10 iu) 48 h later. The intrafollicular pressure in the preovulatory follicle was recorded during 1 h at distinct time phases of the ovulatory process by use of an active servo-null pressure system based on the proportionality between electrical resistance and pressure within the tip of an inserted micropipette. The basal intrafollicular pressure was 16.6 +/- 1.0 mm Hg at the preovulatory phase (48 h after eCG) and increased gradually throughout the ovulatory process to 21.4 +/- 2.4 mm Hg at 4-7 h after hCG (mid-ovulatory phase) and 23.9 +/- 1.9 mm Hg at 8-12 h after hCG (late ovulatory phase; significantly higher (P < 0.01) than the preovulatory phase). Short-term peaks of increased pressure, possibly representing contractility, were not detected in follicles of the preovulatory phase, but were seen in most follicles of the mid- and late ovulatory phases. The mean amplitude of the short-term pressure increases was 12.3 +/- 3.2 mm Hg and the increases occurred at intervals of 24.7 +/- 3.6 s. These short-term increments in intrafollicular pressure were still present after hysterectomy had been performed. The wall tension index was calculated by measuring the follicular size and estimating the thickness of the follicle wall. The index increased from 93.9 +/- 13.3 at the preovulatory phase to 207.3 +/- 47.7 (mid-ovulatory phase) and to significantly higher values at the late ovulatory phase (320.9 +/- 33.5). In conclusion, this study shows that there is an increase in intrafollicular pressure in the ovulating follicle of the rat ovary during the late stages of the ovulatory process, and that short-term increases in intrafollicular pressure occur during the late phase of the ovulatory process. These changes in pressure may be essential for follicular rupture to proceed normally.

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