Effect of adenovirus on metabolism of specific host mRNAs: transport control and specific translational discrimination.

We have studied the adenovirus-induced inhibition of host cell protein synthesis and the effect of infection on the overall metabolism of host cell mRNA during the late phase of adenovirus infection by following the fate of a number of cellular mRNAs complementary to specific cloned DNA segments. At a time in infection when the rate of total cellular protein synthesis is drastically (greater than 90%) reduced, transcription of specific cellular genes is undiminished. However, the transport of newly synthesized cellular mRNA to the cytoplasm is greatly decreased. This decreased appearance of new mRNA in the cytoplasm cannot account for the observed cessation of cell specific protein synthesis, however, since the concentration of several preexisting cellular mRNAs, including the mRNA for actin, remains unchanged throughout the course of infection. The preexisting mRNA is intact, capped, and functional as judged by its ability to direct protein synthesis in vitro in a cap-dependent fashion. The interruption in host translation appears to operate at the level of initiation directly, since we find that fewer ribosomes are associated with a given cellular mRNA after infection than before infection. Furthermore, the in vivo inhibition of cellular protein synthesis does not appear to be the result of competition with viral mRNA, since conditions which prevent the efficient initiation of translation of viral mRNA (infection with a viral mutant) do not result in the recovery of cell translation. Thus, it appears that a late adenovirus gene product directly mediates a shutoff of host protein synthesis.

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Inhibition of Host Protein Synthesis and Degradation of Cellular mRNAs During Infection by Influenza and Herpes Simplex Virus

Molecular and Cellular Biology ◽

10.1128/mcb.2.12.1644 ◽

1982 ◽

Vol 2 (12) ◽

pp. 1644-1648 ◽

Cited By ~ 51

Author(s):

S. C. Inglis

Keyword(s):

Protein Synthesis ◽

Blot Hybridization ◽

Host Protein ◽

Cell Protein ◽

Cellular Genes ◽

Cellular Mrnas ◽

The Stability ◽

Simplex Virus ◽

Host Protein Synthesis ◽

Synthesis And Degradation

Cloned DNA copies of two cellular genes were used to monitor, by blot hybridization, the stability of particular cell mRNAs after infection by influenza virus and herpesvirus. The results indicated that the inhibition of host cell protein synthesis that accompanied infection by each virus could be explained by a reduction in the amounts of cellular mRNAs in the cytoplasm, and they suggested that this decrease was due to virus-mediated mRNA degradation.

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Structural Basis for Competitive Inhibition of eIF4G-Mnk1 Interaction by the Adenovirus 100-Kilodalton Protein

Journal of Virology ◽

10.1128/jvi.78.14.7707-7716.2004 ◽

2004 ◽

Vol 78 (14) ◽

pp. 7707-7716 ◽

Cited By ~ 37

Author(s):

Rafael Cuesta ◽

Qiaoran Xi ◽

Robert J. Schneider

Keyword(s):

Protein Synthesis ◽

Competitive Inhibition ◽

Late Phase ◽

Mrna Translation ◽

Cellular Protein ◽

Structural Basis ◽

Binding Motif ◽

Amino Acid Peptide ◽

Cellular Mrnas ◽

Cellular Protein Synthesis

ABSTRACT Translation of most cellular mRNAs involves cap binding by the translation initiation complex. Among this complex of proteins are cap-binding protein eIF4E and the eIF4E kinase Mnk1. Cap-dependent mRNA translation generally correlates with Mnk1 phosphorylation of eIF4E when both are bound to eIF4G. During the late phase of adenovirus (Ad) infection translation of cellular mRNA is inhibited, which correlates with displacement of Mnk1 from eIF4G by the viral 100-kDa (100K) protein and dephosphorylation of eIF4E. Here we describe the molecular mechanism for 100K protein displacement of Mnk1 from eIF4G and elucidate a structural basis for eIF4G interaction with Mnk1 and 100K proteins and Ad inhibition of cellular protein synthesis. The eIF4G-binding site is located in an N-terminal 66-amino-acid peptide of 100K which is sufficient to bind eIF4G, displace Mnk1, block eIF4E phosphorylation, and inhibit eIF4F (cap)-dependent cellular mRNA translation. Ad 100K and Mnk1 proteins possess a common eIF4G-binding motif, but 100K protein binds more strongly to eIF4G than does Mnk1. Unlike Mnk1, for which binding to eIF4G is RNA dependent, competitive binding by 100K protein is RNA independent. These data support a model whereby 100K protein blocks cellular protein synthesis by coopting eIF4G and cap-initiation complexes regardless of their association with mRNA and displacing or blocking binding by Mnk1, which occurs only on preassembled complexes, resulting in dephosphorylation of eIF4E.

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Transcriptional and translational events during reovirus infection

Biochemistry and Cell Biology ◽

10.1139/o88-092 ◽

1988 ◽

Vol 66 (8) ◽

pp. 803-812 ◽

Cited By ~ 4

Author(s):

Guy Lemay

Keyword(s):

Protein Synthesis ◽

Host Cell ◽

Mrna Translation ◽

Cell Membrane Permeability ◽

Cell Protein ◽

Viral Mrna ◽

Genomic Rna ◽

Host Cell Protein ◽

Outer Capsid ◽

Viral Genomic Rna

This short review focuses on the mechanisms involved in transcription and translation in mouse L cells infected with reoviruses. The viral genomic RNA (double-stranded), retained in the inner capsid following removal of the outer capsid of the infecting virion, is transcribed by a viral polymerase. The synthesized viral mRNA is blocked at the 5′ end by a cap structure similar to the cap structure of cellular mRNA but synthesized by the viral enzymes of the inner capsid. This viral mRNA is also used as the first strand and template for the synthesis of the second strand of viral genomic RNA; the newly replicated genome is retained in an inner capsid structure to generate the progeny subviral particles. These particles are active at the transcriptional level but do not synthesize the cap, owing to the absence of the guanylyltransferase activity involved in the formation of this structure. The uncapped mRNA, or late viral mRNA, constitutes the bulk part of viral mRNA. The transcription of the viral genome is finally arrested upon addition of outer capsid proteins to obtain a mature virion. During viral multiplication, there is a gradual inhibition of host-cell protein synthesis, concomitant with stimulation of late viral mRNA translation. The two phenomena are apparently distinct. Furthermore, the inhibition of host-cell protein synthesis has been shown to be dispensable for normal virus multiplication; however, it might accelerate it. The mechanisms responsible for inhibition are still unclear but might involve modifications in the activity of cellular cap-binding proteins. This last point suggests an analogy with poliovirus infection; the two systems are thus briefly compared. Possible significance of the absence of a poly(A) tract at the 3′ end of reovirus mRNA, in contrast to the occurrence of such a sequence at the end of cellular mRNA, is also examined. Different models involving cap discrimination, competition between mRNAs, or alteration of cell membrane permeability have been proposed to explain the events observed at the translational level in reovirus-infected cells. These different models are compared. Finally, recent data implicating the viral sigma 3 capsid protein in efficient translation of late viral mRNA are discussed.

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A viral kinase mimics S6 kinase to enhance cell proliferation

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1600587113 ◽

2016 ◽

Vol 113 (28) ◽

pp. 7876-7881 ◽

Cited By ~ 16

Author(s):

Aadra Prashant Bhatt ◽

Jason P. Wong ◽

Marc S. Weinberg ◽

Kurtis M. Host ◽

Louise C. Giffin ◽

...

Keyword(s):

Protein Synthesis ◽

Host Cell ◽

Cellular Proliferation ◽

Cellular Protein ◽

Cell Protein ◽

Tubule Formation ◽

S6 Kinase ◽

Reading Frame ◽

Global Protein Synthesis ◽

Fructose 2

Viruses depend upon the host cell for manufacturing components of progeny virions. To mitigate the inextricable dependence on host cell protein synthesis, viruses can modulate protein synthesis through a variety of mechanisms. We report that the viral protein kinase (vPK) encoded by open reading frame 36 (ORF36) of Kaposi’s sarcoma-associated herpesvirus (KSHV) enhances protein synthesis by mimicking the function of the cellular protein S6 kinase (S6KB1). Similar to S6KB1, vPK phosphorylates the ribosomal S6 protein and up-regulates global protein synthesis. vPK also augments cellular proliferation and anchorage-independent growth. Furthermore, we report that both vPK and S6KB1 phosphorylate the enzyme 6-phosphofructo-2-kinase/fructose-2, 6-bisphosphatase 2 (PFKFB2) and that both kinases promote endothelial capillary tubule formation.

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Inhibition of Host Protein Synthesis and Degradation of Cellular mRNAs During Infection by Influenza and Herpes Simplex Virus

Molecular and Cellular Biology ◽

10.1128/mcb.2.12.1644-1648.1982 ◽

1982 ◽

Vol 2 (12) ◽

pp. 1644-1648

Author(s):

S. C. Inglis

Keyword(s):

Protein Synthesis ◽

Blot Hybridization ◽

Host Protein ◽

Cell Protein ◽

Cellular Genes ◽

Cellular Mrnas ◽

The Stability ◽

Simplex Virus ◽

Host Protein Synthesis ◽

Synthesis And Degradation

Cloned DNA copies of two cellular genes were used to monitor, by blot hybridization, the stability of particular cell mRNAs after infection by influenza virus and herpesvirus. The results indicated that the inhibition of host cell protein synthesis that accompanied infection by each virus could be explained by a reduction in the amounts of cellular mRNAs in the cytoplasm, and they suggested that this decrease was due to virus-mediated mRNA degradation.

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Evasion of Cellular Antiviral Responses by Human Cytomegalovirus TRS1 and IRS1

Journal of Virology ◽

10.1128/jvi.78.1.197-205.2004 ◽

2004 ◽

Vol 78 (1) ◽

pp. 197-205 ◽

Cited By ~ 105

Author(s):

Stephanie J. Child ◽

Morgan Hakki ◽

Katherine L. De Niro ◽

Adam P. Geballe

Keyword(s):

Protein Synthesis ◽

Host Cell ◽

Human Cytomegalovirus ◽

Rna Binding ◽

Human Fibroblasts ◽

Cellular Protein ◽

Translation Initiation Factor ◽

Initiation Factor ◽

Rnase L ◽

Cellular Protein Synthesis

ABSTRACT During infection with human cytomegalovirus (HCMV), cellular protein synthesis continues even as viral proteins are being synthesized in abundance. Thus, HCMV may have a mechanism for counteracting host cell antiviral pathways that act by shutting off translation. Consistent with this view, HCMV infection of human fibroblasts rescues the replication of a vaccinia virus mutant lacking the double-stranded RNA-binding protein gene E3L (VVΔE3L). HCMV also prevents the phosphorylation of the eukaryotic translation initiation factor eIF-2α, the activation of RNase L, and the shutoff of viral and cellular protein synthesis that otherwise result from VVΔE3L infection. To identify the HCMV gene(s) responsible for these effects, we prepared a library of VVΔE3L recombinants containing HCMV genomic fragments. By infecting nonpermissive cells with this library and screening for VV gene expression and replication, we isolated a virus containing a 2.8-kb HCMV fragment that rescues replication of VVΔE3L. The fragment comprises the 3′ end of the J1S open reading frame through the entire TRS1 gene. Analyses of additional VVΔE3L recombinants revealed that the protein encoded by TRS1, pTRS1, as well as the closely related IRS1 gene, rescues VVΔE3L replication and prevent the shutoff of protein synthesis, the phosphorylation of eIF-2α, and activation of RNase L. These results demonstrate that TRS1 and IRS1 are able to counteract critical host cell antiviral response pathways.

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Eukaryotic Initiation Factor 4GII (eIF4GII), but Not eIF4GI, Cleavage Correlates with Inhibition of Host Cell Protein Synthesis after Human Rhinovirus Infection

Journal of Virology ◽

10.1128/jvi.73.4.3467-3472.1999 ◽

1999 ◽

Vol 73 (4) ◽

pp. 3467-3472 ◽

Cited By ~ 94

Author(s):

Yuri V. Svitkin ◽

Alessandra Gradi ◽

Hiroaki Imataka ◽

Shigenobu Morino ◽

Nahum Sonenberg

Keyword(s):

Protein Synthesis ◽

Host Cell ◽

Human Rhinovirus ◽

Host Protein ◽

Initiation Factor ◽

Cell Protein ◽

Eukaryotic Initiation Factor ◽

Host Cell Protein ◽

Rhinovirus Infection ◽

Host Protein Synthesis

ABSTRACT For many members of the Picornaviridae family, infection of cells results in a shutoff of host protein synthesis. For rhinoviruses and enteroviruses, the shutoff has been explained in part by the cleavage of eukaryotic initiation factor 4GI (eIF4GI), a component of the cap-binding protein complex eIF4F. The cleavage of eIF4GI is mediated by the virus-specific proteinase 2Aproand results in inhibition of cap-dependent, but not cap-independent, translation. The inhibition of host protein synthesis after infection with human rhinovirus 14 (HRV-14) lags behind the cleavage of eIF4GI. Recently, we discovered a functional homolog of eIF4GI, termed eIF4GII, and showed that cleavage of eIF4GII coincides with the shutoff of host cell protein synthesis after poliovirus infection (Gradi et al., Proc. Natl. Acad. Sci. USA 95:11089–11094, 1998). We wished to determine whether eIF4GII cleavage kinetics could also explain the lack of correlation between the kinetics of eIF4GI cleavage and the shutoff of host protein synthesis after rhinovirus infection. In this study, we examined the correlation between human rhinovirus-induced shutoff of host protein synthesis and cleavage of eIF4GI and eIF4GII. In HRV-14-infected HeLa cells, almost no intact eIF4GI could be detected by 4 h postinfection, while only 4% of eIF4GII was cleaved at this time. By 6 h, however, 67% of eIF4GII was cleaved, and this cleavage coincided with a significant (60%) decline of host translation. These results suggest that cleavage of both eIF4GI and eIF4GII is required for HRV-mediated inhibition of host cell protein synthesis and that the cleavage of eIF4GII is the rate-limiting step in the shutoff of host cell protein synthesis after rhinovirus infection.

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Cleavage of eukaryotic initiation factor eIF4G and inhibition of host-cell protein synthesis during feline calicivirus infection

Journal of General Virology ◽

10.1099/vir.0.19564-0 ◽

2004 ◽

Vol 85 (5) ◽

pp. 1125-1130 ◽

Cited By ~ 35

Author(s):

Margaret M. Willcocks ◽

Michael J. Carter ◽

Lisa O. Roberts

Keyword(s):

Protein Synthesis ◽

Host Cell ◽

Cellular Protein ◽

Initiation Factor ◽

Cell Protein ◽

Feline Calicivirus ◽

Host Cell Protein ◽

Eukaryotic Translation ◽

Initiation Factors ◽

Eukaryotic Translation Initiation Factors

Caliciviruses are small, non-enveloped, positive-stranded RNA viruses that are pathogenic for both animals and man. Although their capsid structure and genomic organization are distinct from picornaviruses, they have similarities to these viruses in their non-structural proteins. Picornaviruses induce a rapid inhibition of host-cell cap-dependent protein synthesis and this is mainly achieved through cleavage of eIF4G and/or dephosphorylation of 4E-BP1. In this study, the effect of calicivirus infection was examined on host-cell protein synthesis in order to determine whether they also induce host shut-off. We report that infection of cells with feline calicivirus (FCV) leads to the inhibition of cellular protein synthesis. This is accompanied by the cleavage of the eukaryotic translation initiation factors eIF4GI and eIF4GII in a manner reminiscent of that induced by picornaviruses. However, the cleavages occur at different sites. The potential mechanisms of these cleavage events and the implications for the translation of calicivirus mRNA are discussed.

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Rotavirus Nonstructural Protein NSP3 Is Not Required for Viral Protein Synthesis

Journal of Virology ◽

10.1128/jvi.00437-06 ◽

2006 ◽

Vol 80 (18) ◽

pp. 9031-9038 ◽

Cited By ~ 59

Author(s):

Hilda Montero ◽

Carlos F. Arias ◽

Susana Lopez

Keyword(s):

Protein Synthesis ◽

Viral Protein ◽

Nonstructural Protein ◽

Consensus Sequence ◽

Initiation Factor ◽

Cell Protein ◽

Viral Protein Synthesis ◽

Viral Mrnas ◽

Initiation Of Translation ◽

Cellular Mrnas

ABSTRACT Initiation is the rate-limiting step in protein synthesis and therefore an important target for regulation. For the initiation of translation of most cellular mRNAs, the cap structure at the 5′ end is bound by the translation factor eukaryotic initiation factor 4E (eIF4E), while the poly(A) tail, at the 3′ end, is recognized by the poly(A)-binding protein (PABP). eIF4G is a scaffold protein that brings together eIF4E and PABP, causing the circularization of the mRNA that is thought to be important for an efficient initiation of translation. Early in infection, rotaviruses take over the host translation machinery, causing a severe shutoff of cell protein synthesis. Rotavirus mRNAs lack a poly(A) tail but have instead a consensus sequence at their 3′ ends that is bound by the viral nonstructural protein NSP3, which also interacts with eIF4GI, using the same region employed by PABP. It is widely believed that these interactions lead to the translation of rotaviral mRNAs, impairing at the same time the translation of cellular mRNAs. In this work, the expression of NSP3 in infected cells was knocked down using RNA interference. Unexpectedly, under these conditions the synthesis of viral proteins was not decreased, while the cellular protein synthesis was restored. Also, the yield of viral progeny increased, which correlated with an increased synthesis of viral RNA. Silencing the expression of eIF4GI further confirmed that the interaction between eIF4GI and NSP3 is not required for viral protein synthesis. These results indicate that NSP3 is neither required for the translation of viral mRNAs nor essential for virus replication in cell culture.

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