scholarly journals Viral and Cellular mRNA Translation in Coronavirus-Infected Cells

2016 ◽  
pp. 165-192 ◽  
Author(s):  
K. Nakagawa ◽  
K.G. Lokugamage ◽  
S. Makino
Keyword(s):  
Mrna Translation ◽  
Infected Cells

scholarly journals Adenovirus E1B proteins are required for accumulation of late viral mRNA and for effects on cellular mRNA translation and transport.

1985 ◽  
Vol 5 (10) ◽  
pp. 2552-2558 ◽  
Author(s):  
L E Babiss ◽  
H S Ginsberg ◽  
J E Darnell
Keyword(s):  
Mrna Translation ◽  
Mutant Virus ◽  
Viral Mrna ◽  
Mrna Synthesis ◽  
Mrna Transport ◽  
Normal Delivery ◽  
Single Function ◽  
Infected Cells ◽  
Steady State Levels ◽  
Adenovirus E1b

Late in adenovirus infection, large amounts of viral mRNA accumulate while cell mRNA transport and translation decrease. Viruses deleted in the E1B region of type 5 adenovirus do not produce the same outcome: (i) viral mRNA synthesis by the mutants is normal, delivery to the cytoplasm is 50 to 75% of normal, but steady-state levels of viral mRNA are decreased 10-fold; (ii) cell mRNA synthesis and transport continue normally in the mutant virus-infected cell; and (iii) translation of preexisting cell mRNA which is disrupted in wild-type infection remains normal in mutant-virus-infected cells. Thus E1B proteins are required for accumulation of virus mRNA and for induction of the failure of host cell mRNA transport and translation. If a single function is involved, by inference the transport and some aspect of translation of mRNAs could be linked.

scholarly journals Rotavirus variant replicates efficiently although encoding an aberrant NSP3 that fails to induce nuclear localization of poly(A)-binding protein

2012 ◽  
Vol 93 (7) ◽  
pp. 1483-1494 ◽  
Author(s):  
Michelle M. Arnold ◽  
Catie Small Brownback ◽  
Zenobia F. Taraporewala ◽  
John T. Patton
Keyword(s):  
Binding Protein ◽  
Mrna Translation ◽  
Translation Initiation Factor ◽  
Host Protein ◽  
Initiation Factor ◽  
Nuclear Accumulation ◽  
Progeny Virus ◽  
Wild Type ◽  
Isolation And Characterization ◽  
Infected Cells

The rotavirus (RV) non-structural protein NSP3 forms a dimer that has binding domains for the translation initiation factor eIF4G and for a conserved 3′-terminal sequence of viral mRNAs. Through these activities, NSP3 has been proposed to promote viral mRNA translation by directing circularization of viral polysomes. In addition, by disrupting interactions between eIF4G and the poly(A)-binding protein (PABP), NSP3 has been suggested to inhibit translation of host polyadenylated mRNAs and to stimulate relocalization of PABP from the cytoplasm to the nucleus. Herein, we report the isolation and characterization of SA11-4Fg7re, an SA11-4F RV derivative that contains a large sequence duplication initiating within the genome segment (gene 7) encoding NSP3. Our analysis showed that mutant NSP3 (NSP3m) encoded by SA11-4Fg7re is almost twice the size of the wild-type protein and retains the capacity to dimerize. However, in comparison to wild-type NSP3, NSP3m has a decreased capacity to interact with eIF4G and to suppress the translation of polyadenylated mRNAs. In addition, NSP3m fails to induce the nuclear accumulation of PABP in infected cells. Despite the defective activities of NSP3m, the levels of viral protein and progeny virus produced in SA11-4Fg7re- and SA11-4F-infected cells were indistinguishable. Collectively, these data are consistent with a role for NSP3 in suppressing host protein synthesis through antagonism of PABP activity, but also suggest that NSP3 functions may have little or no impact on the efficiency of virus replication in widely used RV-permissive cell lines.

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 Poliovirus 2APro Increases Viral mRNA and Polysome Stability Coordinately in Time with Cleavage of eIF4G

2008 ◽  
Vol 82 (12) ◽  
pp. 5847-5859 ◽  
Author(s):  
Brian J. Kempf ◽  
David J. Barton
Keyword(s):  
De Novo ◽  
Mrna Translation ◽  
Viral Mrna ◽  
Site Mutation ◽  
Initiation Factors ◽  
Eukaryotic Initiation Factors ◽  
Messenger Ribonucleoprotein ◽  
Infected Cells ◽  
The Stability ◽  
Polysome Stability

ABSTRACT Poliovirus (PV) 2A protease (2APro) cleaves eukaryotic initiation factors 4GI and 4GII (eIF4GI and eIF4GII) within virus-infected cells, effectively halting cap-dependent mRNA translation. PV mRNA, which does not possess a 5′ cap, is translated via cap-independent mechanisms within viral protease-modified messenger ribonucleoprotein (mRNP) complexes. In this study, we determined that 2APro activity was required for viral polysome formation and stability. 2APro cleaved eIF4GI and eIF4GII as PV polysomes assembled. A 2ACys109Ser (2APro with a Cys109Ser mutation) protease active site mutation that prevented cleavage of eIF4G coordinately inhibited the de novo formation of viral polysomes, the stability of viral polysomes, and the stability of PV mRNA within polysomes. 2ACys109Ser-associated defects in PV mRNA and polysome stability correlated with defects in PV mRNA translation. 3CPro activity was not required for viral polysome formation or stability. 2APro-mediated cleavage of eIF4G along with poly(rC) binding protein binding to the 5′ terminus of uncapped PV mRNA appear to be concerted mechanisms that allow PV mRNA to form mRNP complexes that evade cellular mRNA degradation machinery.

scholarly journals Human Cytomegalovirus Induces the Endoplasmic Reticulum Chaperone BiP through Increased Transcription and Activation of Translation by Using the BiP Internal Ribosome Entry Site

2010 ◽  
Vol 84 (21) ◽  
pp. 11479-11486 ◽  
Author(s):  
Nicholas J. Buchkovich ◽  
Yongjun Yu ◽  
Francis J. Pierciey ◽  
James C. Alwine
Keyword(s):  
Endoplasmic Reticulum ◽  
Transcriptional Activation ◽  
Internal Ribosome Entry Site ◽  
Hcmv Infection ◽  
Mrna Translation ◽  
Entry Site ◽  
Internal Ribosome Entry ◽  
Unfolded Protein ◽  
Infected Cells ◽  
Protein Response

ABSTRACT The endoplasmic reticulum (ER) chaperone BiP (immunoglobulin binding protein) plays a major role in the control of the unfolded protein response. We have previously shown that BiP levels are dramatically increased during human cytomegalovirus (HCMV) infection, where BiP performs unique roles in viral assembly and egress. We show that BiP mRNA levels increase during infection due to activation of the BiP promoter by the major immediate-early (MIE) proteins. The BiP promoter, like other ER stress-activated promoters, contains endoplasmic reticulum stress elements (ERSEs), which are activated by unfolded protein response (UPR)-induced transcription factors. However, these elements are not needed for MIE protein-mediated transcriptional activation; thus, a virus-specific transcriptional activation mechanism is used. Transcriptional activation results in only a 3- to 4-fold increase in BiP mRNA, suggesting that additional mechanisms for BiP production are utilized. The BiP mRNA contains an internal ribosome entry site (IRES) which increases the level of BiP mRNA translation. We show that utilization of the BiP IRES is dramatically increased in HCMV-infected cells. Utilization of the BiP IRES can be activated by the La autoantigen, also called Sjögren's syndrome antigen B (SSB). We show that SSB/La levels are significantly increased during HCMV infection, and SSB/La depletion causes the loss of BiP IRES utilization and lowers endogenous BiP levels in infected cells. Our data show that BiP levels increase in HCMV-infected cells through the combination of increased BiP gene transcription mediated by the MIE proteins and increased BiP mRNA translation due to SSB/La-induced utilization of the BiP IRES.

scholarly journals Preferential Translation of Vesicular Stomatitis Virus mRNAs Is Conferred by Transcription from the Viral Genome

2006 ◽  
Vol 80 (23) ◽  
pp. 11733-11742 ◽  
Author(s):  
Zackary W. Whitlow ◽  
John H. Connor ◽  
Douglas S. Lyles
Keyword(s):  
Vesicular Stomatitis Virus ◽  
Fluorescent Protein ◽  
Mrna Translation ◽  
Host Protein ◽  
Translation Efficiency ◽  
Viral Mrnas ◽  
Translation Inhibition ◽  
Infected Cells ◽  
Vesicular Stomatitis

ABSTRACT Host protein synthesis is inhibited in cells infected with vesicular stomatitis virus (VSV). It has been proposed that viral mRNAs are subjected to the same inhibition but are predominantly translated because of their abundance. To compare translation efficiencies of viral and host mRNAs during infection, we used an enhanced green fluorescent protein (EGFP) reporter expressed from a recombinant virus or from the host nucleus in stably transfected cells. Translation efficiency of host-derived EGFP mRNA was reduced more than threefold at eight hours postinfection, while viral-derived mRNA was translated around sevenfold more efficiently than host-derived EGFP mRNA in VSV-infected cells. To test whether mRNAs transcribed in the cytoplasm are resistant to shutoff of translation during VSV infection, HeLa cells were infected with a recombinant simian virus 5 (rSV5) that expressed GFP. Cells were then superinfected with VSV or mock superinfected. GFP mRNA transcribed by rSV5 was not resistant to translation inhibition during superinfection with VSV, indicating that transcription in the cytoplasm is not sufficient for preventing translation inhibition. To determine if cis-acting sequences in untranslated regions (UTRs) were involved in preferential translation of VSV mRNAs, we constructed EGFP reporters with VSV or control UTRs and measured the translation efficiency in mock-infected and VSV-infected cells. The presence of VSV UTRs did not affect mRNA translation efficiency in mock- or VSV-infected cells, indicating that VSV mRNAs do not contain cis-acting sequences that influence translation. However, we found that when EGFP mRNAs transcribed by VSV or by the host were translated in vitro, VSV-derived EGFP mRNA was translated 22 times more efficiently than host-derived EGFP mRNA. This indicated that VSV mRNAs do contain cis-acting structural elements (that are not sequence based), which enhance translation efficiency of viral mRNAs.

Translational control by influenza virus: suppression of the kinase that phosphorylates the alpha subunit of initiation factor eIF-2 and selective translation of influenza viral mRNAs

1986 ◽  
Vol 6 (5) ◽  
pp. 1741-1750
Author(s):  
M G Katze ◽  
B M Detjen ◽  
B Safer ◽  
R M Krug
Keyword(s):  
Protein Synthesis ◽  
Influenza Virus ◽  
Mrna Translation ◽  
Initiation Factor ◽  
Alpha Subunit ◽  
Viral Mrna ◽  
Viral Mrnas ◽  
Double Stranded Rna ◽  
Selective Translation ◽  
Infected Cells

Selective translation of influenza viral mRNAs occurs after influenza virus superinfection of cells infected with the VAI RNA-negative adenovirus mutant dl331 (M. G. Katze, Y.-T. Chen, and R. M. Krug, Cell 37:483-490, 1984). Cell extracts from these doubly infected cells catalyze the initiation of essentially only influenza viral protein synthesis, reproducing the in vivo situation. This selective translation is correlated with a 5- to 10-fold suppression of the dl331-induced kinase that phosphorylates the alpha subunit of eucaryotic initiation factor eIF-2. This strongly suggests that influenza virus encodes a gene product that, analogous to the adenoviral VAI RNA, prevents the shutdown of overall protein synthesis caused by an eIF-2 alpha kinase turned on by viral infection. Adenoviral mRNA translation was restored to the extract from the doubly infected cells by the addition of the guanine nucleotide exchange factor eIF-2B, which is responsible for the normal recycling of eIF-2 during protein synthesis. This indicates that the residual kinase in the doubly infected cells leads to a limitation in functional (nonsequestered) eIF-2B and hence functional (GTP-containing) eIF-2 and that under these conditions influenza viral mRNAs are selectively translated over adenoviral mRNAs. Addition of double-stranded RNA to the extracts from these cells restored the eIF-2 alpha kinase to a level approaching that seen in extracts from cells infected with dl331 alone and caused the inhibition of influenza viral mRNA translation. This suggests that the putative influenza viral gene product acts against the double-stranded RNA activation of the kinase and indicates that influenza viral mRNA translation is also linked to the level of functional eIF-2. Our results thus indicate that a limitation in functional eIF-2 which causes a nonspecific reduction in the rate of initiation of protein synthesis results in the preferential translation of the better mRNAs (influenza viral mRNAs) at the expense of the poorer mRNAs (adenoviral mRNAs).

scholarly journals Rotavirus NSP3 Is a Translational Surrogate of the Poly(A) Binding Protein-Poly(A) Complex

2015 ◽  
Vol 89 (17) ◽  
pp. 8773-8782 ◽  
Author(s):  
Matthieu Gratia ◽  
Emeline Sarot ◽  
Patrice Vende ◽  
Annie Charpilienne ◽  
Carolina Hilma Baron ◽  
...  
Keyword(s):  
Binding Protein ◽  
Mrna Translation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Cell Physiology ◽  
Transfected Cells ◽  
Rotavirus Infection ◽  
Cellular Translation ◽  
Infected Cells ◽  
Polyadenylated Mrna

ABSTRACTThrough its interaction with the 5′ translation initiation factor eIF4G, poly(A) binding protein (PABP) facilitates the translation of 5′-capped and 3′-poly(A)-tailed mRNAs. Rotavirus mRNAs are capped but not polyadenylated, instead terminating in a 3′ GACC motif that is recognized by the viral protein NSP3, which competes with PABP for eIF4G binding. Upon rotavirus infection, viral, GACC-tailed mRNAs are efficiently translated, while host poly(A)-tailed mRNA translation is, in contrast, severely impaired. To explore the roles of NSP3 in these two opposing events, the translational capabilities of three capped mRNAs, distinguished by either a GACC, a poly(A), or a non-GACC and nonpoly(A) 3′ end, have been monitored after electroporation of cells expressing all rotavirus proteins (infected cells) or only NSP3 (stably or transiently transfected cells). In infected cells, we found that the magnitudes of translation induction (GACC-tailed mRNA) and translation reduction [poly(A)-tailed mRNA] both depended on the rotavirus strain used but that translation reduction not genetically linked to NSP3. In transfected cells, even a small amount of NSP3 was sufficient to dramatically enhance GACC-tailed mRNA translation and, surprisingly, to slightly favor the translation of both poly(A)- and nonpoly(A)-tailed mRNAs, likely by stabilizing the eIF4E-eIF4G interaction. These data suggest that NSP3 is a translational surrogate of the PABP-poly(A) complex; therefore, it cannot by itself be responsible for inhibiting the translation of host poly(A)-tailed mRNAs upon rotavirus infection.IMPORTANCETo control host cell physiology and to circumvent innate immunity, many viruses have evolved powerful mechanisms aimed at inhibiting host mRNA translation while stimulating translation of their own mRNAs. How rotavirus tackles this challenge is still a matter of debate. Using rotavirus-infected cells, we show that the magnitude of cellular poly(A) mRNA translation differs with respect to rotavirus strains but is not genetically linked to NSP3. Using cells expressing rotavirus NSP3, we show that NSP3 alone not only dramatically enhances rotavirus-like mRNA translation but also enhances poly(A) mRNA translation rather than inhibiting it, likely by stabilizing the eIF4E-eIF4G complex. Thus, the inhibition of cellular polyadenylated mRNA translation during rotavirus infection cannot be attributed solely to NSP3 and is more likely the result of global competition between viral and host mRNAs for the cellular translation machinery.

scholarly journals Direct Stimulation of Translation by the Multifunctional Herpesvirus ICP27 Protein

2006 ◽  
Vol 80 (3) ◽  
pp. 1588-1591 ◽  
Author(s):  
Osmany Larralde ◽  
Richard W. P. Smith ◽  
Gavin S. Wilkie ◽  
Poonam Malik ◽  
Nicola K. Gray ◽  
...  
Keyword(s):  
Viral Gene Expression ◽  
Mrna Translation ◽  
Lytic Cycle ◽  
Viral Gene ◽  
Direct Stimulation ◽  
C Terminus ◽  
Infected Cells ◽  
Simplex Virus ◽  
Tethered Function Assay

ABSTRACT Herpes simplex virus type 1 (HSV-1) ICP27 protein is an essential regulator of viral gene expression with roles at various levels of RNA metabolism in the nucleus. Using the tethered function assay, we showed a cytoplasmic activity for ICP27 in directly enhancing mRNA translation in vivo in the absence of other viral factors. The region of ICP27 required for translational stimulation maps to the C terminus. Furthermore, in infected cells, ICP27 is associated with polyribosomes, indicating a function in translation during the lytic cycle.

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