PACT, a stress-modulated cellular activator of interferon-induced double-stranded RNA-activated protein kinase, PKR

Chandrashekhar V. Patel, Indhira Handy, Tiffany Katease Goldsmith, Rekha C. Patel

Research output: Contribution to journalArticle

161 Citations (Scopus)

Abstract

The interferon (IFN)-induced, double-stranded (ds)RNA-activated serine-threonine protein kinase, PKR, is a key mediator of the antiviral activities of IFNs. In addition, PKR activity is also involved in regulation of cell proliferation, apoptosis, and signal transduction. In vitally infected cells, dsRNA has been shown to bind and activate PKR kinase function, implication of PKR activity in normal cellular processes has invoked activators other than dsRNA because RNAs with perfectly duplexed regions of sufficient length that are able to activate PKR are absent in cellular RNAs. We have recently reported cloning of PACT, a novel protein activator of PKR. PACT heterodimerizes with PKR and activates it by direct protein-protein interaction. Overexpression of PACT in mammalian cells leads to phosphorylation of the α subunit of the eukaryotic initiation factor 2 (eIF2α), the cellular substrate for PKR, and leads to inhibition of protein synthesis. Here, we present evidence that endogenous PACT acts as a protein activator of PKR in response to diverse stress signals such as serum starvation, and peroxide or arsenite treatment. Following exposure of cells to these stress agents, PACT is phosphorylated and associates with PKR with increased affinity. PACT-mediated activation of PKR leads to enhanced eIF2α phosphorylation followed by apoptosis. Based on the results presented here, we propose that PACT is a novel stress-modulated physiological activator of PKR.

Original languageEnglish (US)
Pages (from-to)37993-37998
Number of pages6
JournalJournal of Biological Chemistry
Volume275
Issue number48
DOIs
StatePublished - Dec 1 2000

Fingerprint

eIF-2 Kinase
Double-Stranded RNA
Interferons
Eukaryotic Initiation Factor-2
Phosphorylation
Proteins
RNA
Apoptosis
Signal transduction
Cloning
Protein-Serine-Threonine Kinases
Peroxides
Cell proliferation
Starvation
Antiviral Agents
Organism Cloning
Signal Transduction
Phosphotransferases
Chemical activation
Cells

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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PACT, a stress-modulated cellular activator of interferon-induced double-stranded RNA-activated protein kinase, PKR. / Patel, Chandrashekhar V.; Handy, Indhira; Goldsmith, Tiffany Katease; Patel, Rekha C.

In: Journal of Biological Chemistry, Vol. 275, No. 48, 01.12.2000, p. 37993-37998.

Research output: Contribution to journalArticle

Patel, Chandrashekhar V. ; Handy, Indhira ; Goldsmith, Tiffany Katease ; Patel, Rekha C. / PACT, a stress-modulated cellular activator of interferon-induced double-stranded RNA-activated protein kinase, PKR. In: Journal of Biological Chemistry. 2000 ; Vol. 275, No. 48. pp. 37993-37998.
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