Activation of NF-κB by the dsRNA-dependent protein kinase, PKR involves the IκB kinase complex

Gil, Jesús; Alcamı́, José; Esteban, Mariano

doi:10.1038/sj.onc.1203448

Cited by 122 publications

(100 citation statements)

References 75 publications

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“…To circumvent troubles associated with autophosphorylation activity of the IKK complex, we took advantage of cells lacking both IKK1 and IKK2 (IKK 1,2 0/0 MEFs, a kind gift from Dr I Verma), and of VV expressing kinase dead versions of these proteins (VV IKK1 DN and VV IKK2 DN). We have previously shown that the IKK complex is detected associated with PKR immunoprecipitates (Gil et al, 2000, and Figure 7). Thus, as a ®rst assay PKR was immunoprecipitated from IKK 1,2 0/0 MEFs infected with VV recombinants expressing WT PKR and IKK kinase dead subunits, and in vitro phosphorylation of immunoprecipitated proteins was analysed.…”

Section: Analysis Of Ikk1 and Ikk2 Phosphorylation By Pkrmentioning

confidence: 70%

“…At 20 hpi, cells were collected and luciferase activity measured as indicated in Materials and methods. Gray shadow indicates luciferase background levels obtained in cells infected with 5 pfu/cell of VV complex (Chu et al, 1999;Gil et al, 2000;Zamanian et al, 2000). In order to further demonstrate that PKR catalytic activity is involved in this process, we evaluated the ability of PKR WT and VTL9 to induce IKK activity.…”

Section: Catalytic Activity Of Pkr Is Necessary To Trigger Nf-kb Actimentioning

confidence: 99%

“…Recently, we and others have shown that NF-kB activation by PKR involves the IkB kinase complex (IKK) (Chu et al, 1999;Gil et al, 2000;Zamanian et al, 2000), but the question of how PKR activates IKK is a subject of controversy. It has been shown that PKR-mediated activation of NF-kB can be inhibited by blocking PKR catalytic activity using the chemical inhibitor 2-aminopurine (Kumar et al, 1994;Cheshire et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

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The catalytic activity of dsRNA-dependent protein kinase, PKR, is required for NF-κB activation

et al. 2001

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The double stranded RNA-dependent protein kinase (PKR), in addition to its role as a translational controlling factor, is a key transcriptional regulator exerting antiviral and antitumoral activities. We have previously shown that induction of NF-kB by PKR is involved in apoptosis commitment and this process is mediated through activation of the IKK complex. To gain insights into the mechanism of activation of NF-kB by PKR, we have analysed the domains of PKR involved in IKK activation and subsequent NF-kB induction. In PKR 0/0 cells infected with a collection of vaccinia virus (VV) recombinants expressing di erent mutant forms of PKR, we found that only PKR forms conserving the catalytic activity are able to activate NF-kB. An inactive PKR mutant (K296R), was unable to induce NF-kB activation despite full expression of the protein in a wide range of concentrations, as de®ned by Western blot, EMSA, IKK kinase activity and NF-kB transactivation assays. Moreover, the mutant PKR (K296R) acts as a dominant negative of PKR-induced eIF-2a phosphorylation and NF-kB activation. However, PKR mutants unable to activate NF-kB still retain their ability to associate with the IKK complex, as con®rmed by immunoprecipitation analysis. We conclude that the catalytic activity of PKR and not only a protein-protein interaction with the IKK complex, is needed for activation of the transcription factor NF-kB. Oncogene (2001) 20, 385 ± 394.

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Section: Analysis Of Ikk1 and Ikk2 Phosphorylation By Pkrmentioning

confidence: 70%

Section: Catalytic Activity Of Pkr Is Necessary To Trigger Nf-kb Actimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The catalytic activity of dsRNA-dependent protein kinase, PKR, is required for NF-κB activation

et al. 2001

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“…3b). These results suggested that LANA2 is able to interfere with apoptotic effects triggered by PKR activation.Since PKR induces NFkB activation (Kumar et al, 1994;Gil et al, 2000), the effect of LANA2 over PKR-induced NFkB activation was analysed. LANA2 was unable to inhibit NFkB activation in response to PKR (data not shown).…”

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confidence: 99%

The latency protein LANA2 from Kaposi's sarcoma-associated herpesvirus inhibits apoptosis induced by dsRNA-activated protein kinase but not RNase L activation

Esteban

García

Domingo-Gil

et al. 2003

Journal of General Virology

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Kaposi's sarcoma-associated herpesvirus (KSHV) uses several strategies to counteract the interferon (IFN) system. In this study, the relationship of the protein LANA2 from KSHV to the IFN-activated protein kinase (PKR) and 2-5A system was analysed. It was found that LANA2 could not abrogate apoptosis or RNA degradation mediated by the 2-5A system. However, expression of LANA2 inhibited apoptosis triggered by PKR. LANA2 also counteracted the PKR-mediated inhibition of protein synthesis and partially blocked PKR-induced phosphorylation of eIF-2a. Analysis of PKR-induced activation of caspases 3 and 9 revealed that LANA2 abrogated activation of caspase 3 but not of caspase 9. These findings show that LANA2 is able to interfere with downstream events triggered by PKR. Hence, LANA2 should be considered as a KSHV defence protein against IFN. INTRODUCTIONVirus infection induces expression of a group of proteins, the interferons (IFNs), which play major roles as a first-line host defence response against pathogens. IFNs are multifunctional cytokines with important roles in the induction of antiviral, cell growth, differentiation and immunomodulatory functions (Harada et al., 1998;Stark et al., 1998). There are two types of IFN, type I (IFN-a/b) and type II (IFN-c). Type I IFNs are produced by virus-infected cells and constitute the primary response against virus infection, whereas type II IFN is a Th1 cytokine produced by activated T cells and natural killer cells and is involved in immune regulation (Vilcek & Sen, 1996;Stark et al., 1998). Induction of IFN is highly regulated through IFN regulatory factors (IRFs), a family of transcription factors with a broad range of activities (Nguyen et al., 1997;Mamane et al., 1999;Taniguchi et al., 2001). The different biological actions of IFN are mediated by the products of specifically induced cellular genes in target cells. Two of these IFN-regulated cellular products are the dsRNA-activated protein kinase (PKR) and the 2-5A system. PKR controls cell growth (Chong et al., 1992), cell differentiation (Petryshyn et al., 1984), virus clearance (Lee & Esteban, 1993;Lee et al., 1996) and induction of apoptosis (Lee & Esteban, 1994). PKR is a serine/threonine kinase activated by dsRNA binding and exerts its effect on subsequent autophosphorylation. Some targets of the activated PKR are the phosphorylation of the eukaryotic translation initiation factor 2 (eIF-2a) and NFkB activation, events that mediate the induction of apoptosis by PKR. Activation of the caspase 9 pathway together with the fas-associated death domain (FADD)/caspase 8 pathway are also events downstream of PKR-induced apoptosis, although this activation is not required for the induction of apoptosis (Gil et al., 2002). The 2-5A pathway is constituted by the IFN-induced proteins 2-5A synthetase and 2-5A-dependent RNase L, together with 2-5A phosphodiesterase. dsRNA activates the 2-5A synthetases that, in the presence of ATP, synthesize a complex mixture (referred to as 2-5AS) of 2959-triphosphorylated oligoadenylic a...

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“…PKR-mediated apoptosis is caused by activation of an FADD/caspase-8 signaling pathway [9]. PKR activates a transcription factor NF-κB [8,27], which plays a key role in the expression of many immunomodulatory gene products such as cytokines and the MHC class I molecule [3]. PKR is a target molecule of the signaling pathway via Toll-like receptor-4, wh ich reco gnize s m ic ro bial c om pon en ts suc h as lipopolysaccharide and activates innate and adaptive immune responses [12].…”

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confidence: 99%

The mRNA Regulation of Porcine Double-Stranded RNA-Activated Protein Kinase Gene

Asano

Kon

Agui

2004

The Journal of Veterinary Medical Science

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ABSTRACT. The double-stranded RNA (dsRNA)-activated protein kinase (PKR), which is one of the products of interferon (IFN)-stimulated genes, participates in the biological actions of IFN such as antiviral effects and immune response. In the present study, we identified the primary structure of porcine PKR proteins by cDNA cloning. Porcine PKR protein consisted of 537 amino acids and had two dsRNA-binding domains similarly existing in PKR proteins of other species. The treatment with IFN-α induced the expression of PKR 3.9-fold in a porcine kidney cell line, LLC-PK1. The same results were obtained when the cells were treated with poly(I)•poly(C), but treatment with either IFN-γ or LPS did not induce this gene in LLC-PK1 cells. These results suggest similarity of the regulatory mechanisms in the PKR gene among mammalian species.

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Activation of NF-κB by the dsRNA-dependent protein kinase, PKR involves the IκB kinase complex

Cited by 122 publications

References 75 publications

The catalytic activity of dsRNA-dependent protein kinase, PKR, is required for NF-κB activation

The catalytic activity of dsRNA-dependent protein kinase, PKR, is required for NF-κB activation

The latency protein LANA2 from Kaposi's sarcoma-associated herpesvirus inhibits apoptosis induced by dsRNA-activated protein kinase but not RNase L activation

The mRNA Regulation of Porcine Double-Stranded RNA-Activated Protein Kinase Gene

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