Potential role of PKR in double-stranded RNA-induced macrophage activation.
In this study, the role of the double-stranded (ds) RNA-dependent protein kinase (PKR) in macrophage activation was examined. dsRNA [polyinosinic:polycytidylic acid (poly IC)]-stimulated inducible nitric oxide synthase, interleukin (IL)-1alpha and IL-1beta mRNA expression, nitrite formation and IL-1 release are attenuated in RAW264.7 cells stably expressing dominant negative (dn) mutants of PKR. The transcriptional regulator nuclear factor (NF)-kappaB is activated by dsRNA, and appears to be required for dsRNA-induced macrophage activation. While dnPKR mutants prevent macrophage activation, they fail to attenuate dsRNA-induced IkappaB degradation or NF-kappaB nuclear localization. The inhibitory actions of dnPKR on dsRNA-induced macrophage activation can be overcome by treatment with interferon (IFN)-gamma, an event associated with PKR degradation. Furthermore, dsRNA + IFN-gamma stimulate inducible nitric oxide synthase expression, IkappaB degradation and NF-kappaB nuclear localization to similar levels in macrophages isolated from PKR(-/-) and PKR(+/+) mice. These findings indicate that both NF-kappaB and PKR are required for dsRNA-induced macrophage activation; however, dsRNA-induced NF-kappaB activation occurs by PKR-independent mechanisms in macrophages. In addition, the PKR dependence of dsRNA-induced macrophage activation can be overcome by IFN-gamma.
Maggi
L B
LB
The Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, 1402 South Grand Blvd, St Louis, MO 63104, USA.
Heitmeier
M R
MR
Scheuner
D
D
Kaufman
R J
RJ
Buller
R M
RM
Corbett
J A
JA
D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D004790:Enzyme Induction / Q000187:drug effects; D020672:I-kappa B Proteins / Q000378:metabolism; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000235:genetics / Q000378:metabolism; D008262:Macrophage Activation / Q000187:drug effects*; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D011070:Poly I-C / Q000494:pharmacology; D012330:RNA, Double-Stranded / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D019892:eIF-2 Kinase / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
D020672:I-kappa B Proteins; D007375:Interleukin-1; D016328:NF-kappa B; D012330:RNA, Double-Stranded; D012333:RNA, Messenger; D009569:Nitric Oxide; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D019892:eIF-2 Kinase; D011070:Poly I-C