Inhibition of protein synthesis in reovirus-infected HeLa cells with elevated levels of interferon-induced protein kinase activity.

T W Nilsen,C Baglioni,P A Maroney

doi:10.1016/s0021-9258(18)33315-5

T W Nilsen, C Baglioni + Show 1 more

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https://doi.org/10.1016/s0021-9258(18)33315-5

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Abstract

Protein synthesis was inhibited in one line of interferon-treated HeLa cells (line 2) upon infection with reovirus, but not in different HeLa cells (line 1) treated in the same way. The inhibition resulted in polysome runoff, suggesting that it was due to an impairment of peptide chain initiation. Interferon induces the synthesis of a protein kinase, which is activated in cell-free systems by double-stranded RNA and phosphorylates the alpha subunit of eukaryotic initiation factor 2, thus inhibiting the initiation of protein synthesis. Therefore, we measured the level of this protein kinase in extracts prepared from the two HeLa cell lines. Cells of line 2 showed about 3-4 times more protein kinase activity than cells of line 1. The inhibition of protein synthesis upon infection with reovirus was correlated with an increased phosphorylation of the alpha subunit of eukaryotic initiation factor 2 in interferon-treated cells labeled with 32P. The kinase was presumably activated in intact cells by viral double-stranded RNA, but this activation resulted in inhibition of protein synthesis only in cells with elevated levels of the kinase.

Highlights

From the Departmenot fBiological Sciences, State University of New York a t Albany, Albany, New York 12222 virus ( 7 ) .We proposedthat the(2’-5’)oligo(A)polymerase was activated in these cells by dsRNA of viral origin and showed that cellular and presumably viral RNA was cleaved by the (2’-5’)oligo(A)-activatedendonuclease [5]
In HeLa cells of line 2, protein synthesis was progressively inhibited after3 h of infection (Fig. 1).This inhibition wasgreater in cells infected with 20 plaque-forming units of reovirus than in cells infected with 5 plaque-forming units, suggesting that it was correlated with the multiplicity of infection
Protein synthesiswas inhibited uponinfection with reovirus in interferon-treatedHeLa cells with elevated levels of dsRNA-activated proteinkinase, whereas it was not inhibited in a differentHeLa cell line with low levels of this kinase

Summary

Introduction

From the Departmenot fBiological Sciences, State University of New York a t Albany, Albany, New York 12222 virus ( 7 ) .We proposedthat the(2’-5’)oligo(A)polymerase was activated in these cells by dsRNA of viral origin and showed that cellular and presumably viral RNA was cleaved by the (2’-5’)oligo(A)-activatedendonuclease [5]. The inhibition of protein synthesis upon infection with reovirus was correlated with an increased phosphorylation of the a subunit of eukaryotic initiation factor 2 in interferon-treated cells labeled with 32PT.he kinase was presumably activated in intact cells by viral double-stranded RNA, but this treated cells infected with reovirus.

Results

Conclusion