Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0038362 (stomatitis)
 8,852 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cDNA encoding interferon-induced human double-stranded RNA-activated p68 kinase was expressed in murine NIH 3T3 cells by using the pcDNA1/neo vector. Several stable clones were selected which expressed either the wild-type kinase or an inactive mutant possessing a single amino acid substitution in the invariant lysine 296 in the catalytic domain II. The transfected wild-type kinase showed properties similar to those of the natural kinase, such as subcellular ribosomal localization and dependence on double-stranded RNA for autophosphorylation. Upon infection with encephalomyocarditis virus (EMCV), wild-type- but not mutant-expressing clones were found to partially resist virus growth. Such natural antiviral activity was virus specific, since no inhibition was observed in the case of vesicular stomatitis virus infection. In accord with EMCV inhibition, the wild-type p68 kinase was found to be highly phosphorylated during infection. Furthermore, its natural substrate, the small subunit of protein synthesis initiation factor eIF2, was phosphorylated. These results demonstrate that p68 kinase is activated during EMCV infection, leading to reduced virus production.
 ...
PMID:Constitutive expression of human double-stranded RNA-activated p68 kinase in murine cells mediates phosphorylation of eukaryotic initiation factor 2 and partial resistance to encephalomyocarditis virus growth. 138 42

The double-stranded RNA-dependent protein kinase from human cells is a 68,000 molecular weight protein (p68 kinase), the level of which is enhanced significantly in cells treated with interferon. With a monoclonal antibody specific for p68 kinase, here we show the phosphorylation and steady-state levels of p68 kinase during virus infection. The p68 kinase is phosphorylated in interferon-treated cells during infection with encephalomyocarditis virus (EMCV), vesicular stomatitis virus (VSV), and vaccinia virus, thus indicating activation of p68 kinase during these virus infections, an essential step required for autophosphorylation of p68 kinase. However, in spite of this activation, the level of p68 kinase is rapidly decreased in virus-infected cells. The half-life of p68 kinase in uninfected cells is 6 to 7 hr, whereas in EMCV-infected cells it is 2 to 3 hr. This decrease in the level of p68 kinase is dependent on the multiplicity of virus infection and it seems to be specific since other cellular proteins as well as the activity of 2'-5'-oligoadenylate synthetase are not modified. Decreased levels of p68 kinase are also observed in cells infected with VSV and vaccinia virus. In the absence of virus infection, decreased levels of p68 kinase occur in cells following incubation with poly(I).poly(C).
 ...
PMID:Rapid decrease in the levels of the double-stranded RNA-dependent protein kinase during virus infections. 244 Jan 79

We have developed a selection protocol to isolate interferon (IFN)-sensitive subclones directly from an IFN-resistant cell population. The protocol uses encephalomyocarditis virus (EMCV) as a selection agent in combination with pretreatment with low doses of IFN and subsequent growth in the presence of virus-neutralizing antiserum. We have applied this protocol to the partially IFN-resistant NIH 3T3 clone 1 line and have obtained a number of IFN-sensitive subclones. Sensitivity to IFN was restricted to protection against EMCV. Replication of vesicular stomatitis virus as well as cell growth were resistant to IFN treatment as in the original clone 1 line. We have compared levels of 2',5'-oligoadenylate (2-5A) synthetase, dsRNA-activated protein kinase and 2-5A-dependent RNase in some IFN-sensitive subclones and found no difference from the resistant clone 1 cells. Markedly decreased levels of 2-5A-dependent RNase and thus a defective 2-5A pathway have been implicated as a possible cause for the partial resistance of clone 1 cells to IFN. Since the selected IFN-sensitive subclones are of the same phenotype in this respect as the clone 1 line we suggest that inhibition of EMCV in these lines occurs through a mechanism independent of the 2-5A system.
 ...
PMID:Selection and characterization of interferon-sensitive cells derived from an interferon-resistant NIH 3T3 line. 244 7

Previous studies have shown that the antiviral response induced by interferon in murine cells could be degraded after a heat shock. Here we have confirmed that a similar effect occurs also in interferon-treated human HeLa cells subjected to a heat shock. In addition, we have investigated the fate of the interferon-induced, double-stranded RNA-dependent protein kinase in heat-shocked cells. This protein kinase is a Mr 68,000 protein (p68 kinase) which, when autophosphorylated, catalyzes phosphorylation of the protein synthesis eukaryotic initiation factor-2, thus mediating inhibition of protein synthesis. After heat shock of interferon-treated HeLa cells, the double-stranded RNA-dependent autophosphorylation of p68 kinase in cytoplasmic extracts is greatly reduced whereas the phosphorylation of other cellular proteins is not affected. In vivo, autophosphorylation of p68 kinase is also reduced in heat-shocked cells whereas there is no apparent effect on the phosphorylation state of other proteins. In such cells, the interferon-mediated antiviral response becomes modified according to the virus challenge, i.e. these cells remain resistant to vesicular stomatitis virus but become partially sensitive to encephalomyocarditis virus (EMCV) infection. The reduction in the activity of p68 kinase is due to its reduced nonionic detergent solubility occurring during the heat shock period. The resultant reduced detergent extractibility of p68 kinase is dependent on the intensity of the thermal stress. In contrast to the effect after a heat shock, arsenite treatment of interferon-treated HeLa cells induces heat shock proteins, but neither modifies the antiviral response nor affects the extractibility of p68 kinase. These results indicate that the degradation of the anti-EMCV response and reduced p68 kinase activity occur in response to heat treatment independently of the induction of heat shock proteins. The role of p68 kinase in the mechanism of the antiviral response against EMCV and vesicular stomatitis virus is discussed.
 ...
PMID:Reduced activity of the interferon-induced double-stranded RNA-dependent protein kinase during a heat shock stress. 254

Protein synthesis in interferon-treated HeLa cells infected by different animal RNA viruses has been studied. Synthesis of vesicular stomatitis virus (VSV) proteins was not detected in cells treated with concentrations of HuIFN-alpha (Ly) above 10 IU/ml. No specific inhibition of glycosylation of the G protein was observed. In addition, inhibition of host protein synthesis in IFN-treated cells occurred when high multiplicities of VSV were used, even though no viral protein synthesis was detected. For other viruses, such as Newcastle disease virus, Semliki Forest virus, encephalomyocarditis virus and poliovirus, treatment of cells with interferon also led to inhibition of viral protein synthesis. However, influenza virus and reovirus protein synthesis in interferon-treated cells stayed at control levels. The finding of viral translation in influenza virus and reovirus-infected cells treated with interferon suggests that, at least for these two systems, the antiviral state is not mediated by the bulk inhibition of viral protein synthesis through the dsRNA-activated protein kinase, or the 2'-5' oligo(A) system.
 ...
PMID:Action of human lymphoblastoid interferon on HeLa cells infected with RNA-containing animal viruses. 631 80

A direct antiviral role of the interferon-induced human protein kinase p68 has been shown only against encephalomyocarditis virus (EMCV) and vaccinia virus (VV). To determine if p68 kinase (PKR) has a broad antiviral effect, we have used coinfections between VV recombinants expressing p68 kinase under regulation of the lac I operator/repressor elements of Escherichia coli and two RNA viruses, vesicular stomatitis virus (VSV) and poliovirus. In cells coinfected with VV recombinants and VSV, induction with isopropyl-B-D-thiogalactoside (IPTG) of wild-type p68 kinase or a mutant lacking the dsRNA binding domain resulted in inhibition of both VV and VSV protein synthesis. This inhibition is not observed in cells infected with a catalytically inactive point mutant lys-arg296 of p68 kinase. When cells are coinfected with VV recombinants and poliovirus, induction of active p68 kinase resulted in a decrease in VV proteins but not in poliovirus proteins or poliovirus yields. Immunoblot analysis revealed that p68 kinase was expressed during mixed infections. Our results demonstrate a differential effect of p68 kinase on the replication of VV, VSV, and poliovirus. We suggest that in a particular virus-cell system, the different sensitivity of a virus to p68 kinase is probably due to levels of active enzyme.
 ...
PMID:Regulated expression of the interferon-induced protein kinase p68 (PKR) by vaccinia virus recombinants inhibits the replication of vesicular stomatitis virus but not that of poliovirus. 897 11

Retinoic acid (RA) and interferons (IFNs) are negative regulators of cell proliferation. In vitro and in vivo, their combination leads to a more potent growth inhibition. However, the molecular mechanisms by which RA and IFNs potentiate each other are not fully understood. As some IFN-induced gene products regulate cell growth and/or antiviral activity, we analysed the effects of RA on their expressions. RA increases the level of 2'5'oligoadenylate synthetase, p68 kinase, the promyelocytic leukemia protein (PML) and Sp100 in both HL-60 and WISH cells. Moreover, RA and IFN act cooperatively to increase the expression of these proteins. RA also inhibits vesicular stomatitis virus replication and induces a higher antiviral state and growth inhibition when combined with IFN. RA stimulates the IFN regulatory factor 1 (IRF-1) gene expression directly through the GAS motif and causes the induction and secretion of IFNalpha. Additional mechanisms could be involved as RA increases the level of signal transducing activators of transcription (STAT) proteins, and enhances the IFN-induced STAT activation, suggesting that cooperative effects by RA and IFN are mediated through multiple pathways.
 ...
PMID:Retinoic acid enhances the expression of interferon-induced proteins: evidence for multiple mechanisms of action. 939 79

Interferons (IFNs) are potent antiviral cytokines that inhibit infection by a wide spectrum of viruses by activating the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway. Several IFN-induced antiviral proteins including 2',5'-oligoadenylate synthetase, dsRNA-activated protein kinase and Mx play a critical role in conferring the antiviral properties of IFN. However, studies have shown that additional antiviral factors are involved in addition to these proteins during IFN-mediated antiviral action. In an effort to characterize these novel antiviral factors, the antiviral mechanism of alpha IFN (IFN-alpha) against vesicular stomatitis virus (VSV) was investigated in human lung epithelial A549 cells. These studies demonstrated that soluble secreted antiviral proteins as the constituents of conditioned medium prepared from IFN-alpha-treated cells reduced VSV infectivity by more than 2 logs, compared with a 4 log inhibition observed following treatment of cells with IFN-alpha. The antiviral mechanism of these secreted proteins appeared to act at the level of cellular entry of VSV. Interestingly, the IFN-alpha-induced antiviral proteins were secreted independently of STAT1 (an essential component of the JAK/STAT pathway), demonstrating that the release of such extracellular soluble antiviral proteins from cells may represent an alternative mechanism of the antiviral defence strategy of IFN towards VSV infection.
 ...
PMID:Inhibition of vesicular stomatitis virus infection in epithelial cells by alpha interferon-induced soluble secreted proteins. 1689 5

In a companion paper (D. Ostertag, T. M. Hoblitzell-Ostertag, and J. Perrault, J. Virol. 81:492-502, 2007), we provided indirect evidence that cell-type-specific growth restriction of the vesicular stomatitis virus (VSV) polR mutants may be due to enhanced production of double-stranded RNA (dsRNA). We show here that polR growth in mouse L-929 cells was rescued by vaccinia virus coinfection and that sole expression of the vaccinia virus dsRNA-binding E3L protein, via coinfection with an engineered VSV minigenome, also restored polR growth. Expression of dsRNA-binding protein NS1A or NS1B from influenza virus, but not C protein from Sendai virus, which does not bind dsRNA, likewise effected polR rescue. The N-terminal dsRNA-binding domain of NS1A, only 73 amino acids in length, but not a full-size mutant NS1A lacking dsRNA-binding activity, restored polR growth. Both key aspects of polR growth restriction, namely inhibition of genome replication and release of low-infectivity virus particles, were countered by expression of the dsRNA-binding proteins. We tested the effects of overproducing dsRNA in wild-type VSV infections by coinfecting cells with a VSV recombinant expressing the sense strand of the enhanced green fluorescent protein gene (VSV-GFP) and one expressing the antisense strand (VSV-PFG). These coinfections mimicked all aspects of polR restriction, including host range, lack of effect on transcription, reduced virus particle infectivity, and insensitivity to inhibition of host gene transcription or dsRNA-activated protein kinase activity. We conclude that, for some cell types, overproduction of dsRNA during VSV infection triggers an immediate and constitutive host cell antiviral effector response independent of interferon induction or signaling.
 ...
PMID:Overproduction of double-stranded RNA in vesicular stomatitis virus-infected cells activates a constitutive cell-type-specific antiviral response. 1706 13

The RNA-editing enzyme ADAR1 is a double-stranded RNA (dsRNA) binding protein that modifies cellular and viral RNA sequences by adenosine deamination. ADAR1 has been demonstrated to play important roles in embryonic erythropoiesis, viral response, and RNA interference. In human hepatitis virus infection, ADAR1 has been shown to target viral RNA and to suppress viral replication through dsRNA editing. It is not clear whether this antiviral effect of ADAR1 is a common mechanism in response to viral infection. Here, we report a proviral effect of ADAR1 that enhances replication of vesicular stomatitis virus (VSV) through a mechanism independent of dsRNA editing. We demonstrate that ADAR1 interacts with dsRNA-activated protein kinase PKR, inhibits its kinase activity, and suppresses the alpha subunit of eukaryotic initiation factor 2 (eIF-2alpha) phosphorylation. Consistent with the inhibitory effect on PKR activation, ADAR1 increases VSV infection in PKR+/+ mouse embryonic fibroblasts; however, no significant effect was found in PKR-/- cells. This proviral effect of ADAR1 requires the N-terminal domains but does not require the deaminase domain. These findings reveal a novel mechanism of ADAR1 that increases host susceptibility to viral infection by inhibiting PKR activation.
 ...
PMID:Double-stranded RNA deaminase ADAR1 increases host susceptibility to virus infection. 1707 86


1 2 Next >>