Human p68 kinase exhibits growth suppression in yeast and homology to the translational regulator GCN2.

Chong, Karen; Feng, Lan; Schappert, Keith; Meurs, Éliane; Donahue, Thomas F.; Friesen, James D.; Hovanessian, Ara G.; Williams, Bryan R.G.

doi:10.1002/j.1460-2075.1992.tb05200.x

Cited by 319 publications

(271 citation statements)

References 57 publications

(39 reference statements)

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“…dsRNA-dependent protein kinase is normally activated in response to viral attack, and the depression of protein synthesis resulting from phosphorylation of eIF2a constitutes one of the major ways in which viral replication is impaired (Clemens, 1997). However, PKR can also exert effects in uninfected cells and can be a potent growth inhibitory protein when activated (Chong et al, 1992). dsRNA-dependent protein kinase is also linked to the induction of pro-apoptotic genes by dsRNA, and may trigger cell death in response to viral infection and possible tumorigenesis (Balachandran et al, 1998).…”

Section: Discussionmentioning

confidence: 99%

Increased expression of phosphorylated forms of RNA-dependent protein kinase and eukaryotic initiation factor 2α may signal skeletal muscle atrophy in weight-losing cancer patients

et al. 2007

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Previous studies suggest that the activation (autophosphorylation) of dsRNA-dependent protein kinase (PKR) can stimulate protein degradation, and depress protein synthesis in skeletal muscle through phosphorylation of the translation initiation factor 2 (eIF2) on the a-subunit. To understand whether these mediators are important in muscle wasting in cancer patients, levels of the phospho forms of PKR and eIF2a have been determined in rectus abdominus muscle of weight losing patients with oesophago-gastric cancer, in comparison with healthy controls. Levels of both phospho PKR and phospho eIF2a were significantly enhanced in muscle of cancer patients with weight loss irrespective of the amount and there was a linear relationship between phosphorylation of PKR and phosphorylation of eIF2a (correlation coefficient 0.76, P ¼ 0.005). This suggests that phosphorylation of PKR led to phosphorylation of eIF2a. Myosin levels decreased as the weight loss increased, and there was a linear relationship between myosin expression and the extent of phosphorylation of eIF2a (correlation coefficient 0.77, P ¼ 0.004). These results suggest that phosphorylation of PKR may be an important initiator of muscle wasting in cancer patients.

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Section: Discussionmentioning

confidence: 99%

Increased expression of phosphorylated forms of RNA-dependent protein kinase and eukaryotic initiation factor 2α may signal skeletal muscle atrophy in weight-losing cancer patients

et al. 2007

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“…Construction of the PKR mutants PKR ⌬362-367 in pCDNA1neo (Invitrogen) and of PKR K296R, PKR 1-296, and PKR 244-551 in pET11a (Novagen) and pCDNA1neo was previously described (4,17,41,43). For construction of GAL4 transcriptional activation domain (AD) and GAL4 DNA-binding domain (BD) fusions, the NdeI linker sequence, ccatatgg, was ligated into the SmaI site of pGAD424 (AD) and pGBT9 (BD; Clontech) to generate pGAD425 and pGBT10, respectively.…”

Section: Methodsmentioning

confidence: 99%

Interaction of the Interferon-Induced PKR Protein Kinase with Inhibitory Proteins P58^IPKand Vaccinia Virus K3L Is Mediated by Unique Domains: Implications for Kinase Regulation

Gale

Tan

Wambach

et al. 1996

Molecular and Cellular Biology

104

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Expression of the double-stranded RNA-activated protein kinase (PKR) is induced by interferons, with PKR activity playing a pivotal role in establishing the interferon-induced antiviral and antiproliferative states. PKR is directly regulated by physical association with the specific inhibitor, P58 IPK , a cellular protein of the tetratricopeptide repeat (TPR) family, and K3L, the product of the corresponding vaccinia virus gene. P58 IPK and K3L repress PKR activation and activity. To investigate the mechanism of P58 IPK -and K3L-mediated PKR inhibition, we have used a combination of in vitro and in vivo binding assays to identify the interactive regions of these proteins. The P58 IPK -interacting site of PKR was mapped to a 52-amino-acid aa segment (aa 244 to 296) spanning the ATP-binding region of the protein kinase catalytic domain. The interaction with PKR did not require the C-terminal DNA-J homology region of P58 IPK but was dependent on the presence of the eukaryotic initiation factor 2-␣ homology region, mapping to the 34 aa within the sixth P58 IPK TPR motif. Consistent with other TPR proteins, P58 IPK formed multimers in vivo: the N-terminal 166 aa were both necessary and sufficient for complex formation. A parallel in vivo analysis to map the K3L-binding region of PKR revealed that like P58 IPK , K3L interacted exclusively with the PKR protein kinase catalytic domain. In contrast, however, the K3L-binding region of PKR was localized to within aa 367 to 551, demonstrating that each inhibitor bound PKR in unique, nonoverlapping domains. These data, taken together, suggest that P58 IPK and K3L may mediate PKR inhibition by distinct mechanisms. Finally, we will propose a model of PKR inhibition in which P58 IPK or a P58 IPK complex binds PKR and interferes with nucleotide binding and autoregulation, while formation of a PKR-K3L complex interferes with active-site function and/or substrate association.

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“…Whereas yeast cells lacking GCN2 are unable to grow on medium containing 3-AT, low level expression of heterologous PKR or PERK kinases confers a 3-AT-resistant phenotype (8,9). In addition, high level expression of PKR or PERK inhibits yeast cell growth by impairing general translation (8,10,11). Biochemical analyses demonstrated that PKR and PERK phosphorylate yeast eIF2␣ on Ser 51 both in vivo and in vitro (8,11).…”

mentioning

confidence: 99%

Conserved Intermolecular Salt Bridge Required for Activation of Protein Kinases PKR, GCN2, and PERK

Dey

Cao

Sicheri

et al. 2007

Journal of Biological Chemistry

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The protein kinases PKR, GCN2, and PERK phosphorylate translation initiation factor eIF2␣ to regulate general and genespecific protein synthesis under various cellular stress conditions. Recent x-ray crystallographic structures of PKR and GCN2 revealed distinct dimeric configurations of the kinase domains. Whereas PKR kinase domains dimerized in a back-toback and parallel orientation, the GCN2 kinase domains displayed an antiparallel orientation. The dimerization interfaces on PKR and GCN2 were localized to overlapping surfaces on the N-terminal lobes of the kinase domains but utilized different intermolecular contacts. A key feature of the PKR dimerization interface is a salt bridge interaction between Arg 262 from one protomer and Asp 266 from the second protomer. Interestingly, these two residues are conserved in all eIF2␣ kinases, although in the GCN2 structure, the two residues are too remote to interact. To test the importance of this potential salt bridge interaction in PKR, GCN2, and PERK, the residues constituting the salt bridge were mutated either independently or together to residues with the opposite charge. Single mutations of the Asp (or Glu) and Arg residues blocked kinase function both in yeast cells and in vitro. However, for all three kinases, the double mutation designed to restore the salt bridge interaction with opposite polarity resulted in a functional kinase. Thus, the salt bridge interaction and dimer interface observed in the PKR structure is critical for the activity of all three eIF2␣ kinases. These results are consistent with the notion that the PKR structure represents the active state of the eIF2␣ kinase domain, whereas the GCN2 structure may represent an inactive state of the kinase.

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Human p68 kinase exhibits growth suppression in yeast and homology to the translational regulator GCN2.

Cited by 319 publications

References 57 publications

Increased expression of phosphorylated forms of RNA-dependent protein kinase and eukaryotic initiation factor 2α may signal skeletal muscle atrophy in weight-losing cancer patients

Increased expression of phosphorylated forms of RNA-dependent protein kinase and eukaryotic initiation factor 2α may signal skeletal muscle atrophy in weight-losing cancer patients

Interaction of the Interferon-Induced PKR Protein Kinase with Inhibitory Proteins P58^IPKand Vaccinia Virus K3L Is Mediated by Unique Domains: Implications for Kinase Regulation

Conserved Intermolecular Salt Bridge Required for Activation of Protein Kinases PKR, GCN2, and PERK

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Human p68 kinase exhibits growth suppression in yeast and homology to the translational regulator GCN2.

Cited by 319 publications

References 57 publications

Increased expression of phosphorylated forms of RNA-dependent protein kinase and eukaryotic initiation factor 2α may signal skeletal muscle atrophy in weight-losing cancer patients

Increased expression of phosphorylated forms of RNA-dependent protein kinase and eukaryotic initiation factor 2α may signal skeletal muscle atrophy in weight-losing cancer patients

Interaction of the Interferon-Induced PKR Protein Kinase with Inhibitory Proteins P58IPKand Vaccinia Virus K3L Is Mediated by Unique Domains: Implications for Kinase Regulation

Conserved Intermolecular Salt Bridge Required for Activation of Protein Kinases PKR, GCN2, and PERK

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Interaction of the Interferon-Induced PKR Protein Kinase with Inhibitory Proteins P58^IPKand Vaccinia Virus K3L Is Mediated by Unique Domains: Implications for Kinase Regulation