Enhancement of the Interferon‐Induced Double‐Stranded RNA‐Dependent Protein Kinase Activity by Sindbis Virus Infection and Heat‐Shock Stress

Abstract

In extracts of FL cells that were infected with Sindbis virus or treated with heat-shock stress, dsRNA-dependent phosphorylation of 77K protein was markedly increased.

Inhibitor of Interferon‐Induced Double‐Stranded RNA‐ Dependent Protein Kinase and Its Relevance to Alteration of Cellular Protein Kinase Activity Level in Response to External Stimuli

“…To see if the aquisition of dsRNA responsiveness of PK-I in Sindbis virusinfected and IFN-treated cells may be ascribable to a reduction in the amont of the inhibitor of PK-I activation, RSW fractions were prepared from IFN-treated (1,000 IU, for 8.5 hr and 24 hr), Sindbis virus-infected (4.5 hr) and mock-treated control cells (6 hr), and the phosphorylation of PK-1 was measured in the presence of poly(I): poly(C). PK-I was autophosphorylated dsRNA-dependently in RSW from virus-infected and 1FN-treated cells but not in RSW from mock-treated cells in accordance with previous observations (8). Larger amount of autophosphorylated PK-I in RSW from 24 hr EN-treated cells reflects a net synthesis of PK-1 protein (1).…”

“…PK-I in the mock-treated sample was not phsophorylated (Fig. 3a) even though the PK-I protein itself was present as previously demonstrated (8).…”

“…In our previous paper (8), we reported that the activity of PK-I was transiently enhanced by infection with Sindbis virus or a heat shock stress without concomitant increase of PK-I protein. Similarly, a short-term.…”

Antiviral effect of the mammalian translation initiation factor 2α kinase GCN2 against RNA viruses

“…The most obvious explanation is that it does so by phosphorylating eIF2α, thereby blocking viral translation. Previous reports showed that PKR is activated upon infection with SV (Saito, 1990), and it has been suggested that the PKR‐dependent inhibition of translation is not the only and, most likely, not the major pathway mediating translational shutoff during SV infection (Gorchakov et al , 2004). Our data are consistent with those results but further indicate that PKR activation induced by SV infection is more evident in cells devoid of GCN2, probably because PKR activation in these cells, but not in normal cells, occurs early in the infection as a consequence of the appearance of replicative forms of the viral RNA.…”

Sindbis Virus Translation Is Inhibited by a PKR/RNase L-Independent Effector Induced by Alpha/Beta Interferon Priming of Dendritic Cells

“…Many viruses are susceptible to the two major IFN-␣/␤-inducible, dsRNA-triggered host translational control programs (17,40): the coupled 2Ј-5Ј oligoadenylate synthetase (OAS)/RNase L pathway and the dsRNA-dependent protein kinase (PKR) pathway which provide rapid antiviral activity independent of IFN-␣/␤ signaling (40,43). SB replication activates and is sensitive to both of these antiviral effector mechanisms in murine embryo fibroblasts (38,39,41,42). We have previously demonstrated that early control of SB replication was defective in primary myeloid bone marrow-derived DC (BMDC) cultures generated from mice with targeted disruption of the PKR gene (PKR Ϫ/Ϫ ) or of both the PKR and RNase L genes (triply deficient, or TD), suggesting that the PKR pathway, but not the OAS/RNase L pathway, suppresses virus replication in DCs prior to IFN-␣/␤ induction (37).…”