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

Oncogene. 2001 Jan 18;20(3):385-94. doi: 10.1038/sj.onc.1204109.

Abstract

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-kappaB 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-kappaB by PKR, we have analysed the domains of PKR involved in IKK activation and subsequent NF-kappaB induction. In PKR(0/0) cells infected with a collection of vaccinia virus (VV) recombinants expressing different mutant forms of PKR, we found that only PKR forms conserving the catalytic activity are able to activate NF-kappaB. An inactive PKR mutant (K296R), was unable to induce NF-kappaB activation despite full expression of the protein in a wide range of concentrations, as defined by Western blot, EMSA, IKK kinase activity and NF-kappaB transactivation assays. Moreover, the mutant PKR (K296R) acts as a dominant negative of PKR-induced eIF-2alpha phosphorylation and NF-kappaB activation. However, PKR mutants unable to activate NF-kappaB still retain their ability to associate with the IKK complex, as confirmed 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-kappaB.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Catalytic Domain
  • Cells, Cultured
  • Enzyme Activation
  • Eukaryotic Initiation Factor-2 / metabolism
  • Genes, Dominant
  • Humans
  • I-kappa B Kinase
  • Mice
  • NF-kappa B / metabolism*
  • Phosphorylation
  • Point Mutation
  • Protein-Serine-Threonine Kinases / metabolism
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Vaccinia virus / genetics
  • eIF-2 Kinase / genetics
  • eIF-2 Kinase / metabolism*

Substances

  • Eukaryotic Initiation Factor-2
  • NF-kappa B
  • Recombinant Proteins
  • Protein-Serine-Threonine Kinases
  • eIF-2 Kinase
  • CHUK protein, human
  • Chuk protein, mouse
  • I-kappa B Kinase
  • IKBKB protein, human
  • IKBKE protein, human
  • Ikbkb protein, mouse
  • Ikbke protein, mouse