Novel role of PKR in inflammasome activation and HMGB1 release

Nature. 2012 Aug 30;488(7413):670-4. doi: 10.1038/nature11290.

Abstract

The inflammasome regulates the release of caspase activation-dependent cytokines, including interleukin (IL)-1β, IL-18 and high-mobility group box 1 (HMGB1). By studying HMGB1 release mechanisms, here we identify a role for double-stranded RNA-dependent protein kinase (PKR, also known as EIF2AK2) in inflammasome activation. Exposure of macrophages to inflammasome agonists induced PKR autophosphorylation. PKR inactivation by genetic deletion or pharmacological inhibition severely impaired inflammasome activation in response to double-stranded RNA, ATP, monosodium urate, adjuvant aluminium, rotenone, live Escherichia coli, anthrax lethal toxin, DNA transfection and Salmonella typhimurium infection. PKR deficiency significantly inhibited the secretion of IL-1β, IL-18 and HMGB1 in E. coli-induced peritonitis. PKR physically interacts with several inflammasome components, including NOD-like receptor (NLR) family pyrin domain-containing 3 (NLRP3), NLRP1, NLR family CARD domain-containing protein 4 (NLRC4), absent in melanoma 2 (AIM2), and broadly regulates inflammasome activation. PKR autophosphorylation in a cell-free system with recombinant NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC, also known as PYCARD) and pro-caspase-1 reconstitutes inflammasome activity. These results show a crucial role for PKR in inflammasome activation, and indicate that it should be possible to pharmacologically target this molecule to treat inflammation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism
  • Adenosine Triphosphate / pharmacology
  • Animals
  • Antigens, Bacterial / pharmacology
  • Apoptosis Regulatory Proteins / metabolism
  • Bacterial Toxins / pharmacology
  • CARD Signaling Adaptor Proteins / metabolism
  • Calcium-Binding Proteins / metabolism
  • Carrier Proteins / metabolism
  • Cell Line
  • Cells, Cultured
  • Crystallins / metabolism
  • Escherichia coli / immunology
  • Escherichia coli / physiology
  • Escherichia coli Infections / immunology
  • Escherichia coli Infections / metabolism
  • Female
  • HMGB1 Protein / blood
  • HMGB1 Protein / metabolism*
  • Humans
  • Inflammasomes / agonists
  • Inflammasomes / metabolism*
  • Interleukin-18 / blood
  • Interleukin-1beta / blood
  • Interleukin-6 / analysis
  • Interleukin-6 / blood
  • Macrophages, Peritoneal / drug effects
  • Macrophages, Peritoneal / metabolism
  • Male
  • Membrane Proteins / metabolism
  • Mice
  • Mice, Inbred C57BL
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Peritonitis / metabolism
  • Phosphorylation
  • RNA, Double-Stranded / immunology
  • RNA, Double-Stranded / pharmacology
  • Rotenone / pharmacology
  • Salmonella Infections / immunology
  • Salmonella Infections / metabolism
  • Salmonella typhimurium / immunology
  • Salmonella typhimurium / physiology
  • Transfection
  • Uric Acid / pharmacology
  • eIF-2 Kinase / antagonists & inhibitors
  • eIF-2 Kinase / deficiency
  • eIF-2 Kinase / genetics
  • eIF-2 Kinase / metabolism*

Substances

  • AIM1 protein, human
  • Adaptor Proteins, Signal Transducing
  • Antigens, Bacterial
  • Apoptosis Regulatory Proteins
  • Bacterial Toxins
  • CARD Signaling Adaptor Proteins
  • Calcium-Binding Proteins
  • Carrier Proteins
  • Crystallins
  • HMGB1 Protein
  • Inflammasomes
  • Interleukin-18
  • Interleukin-1beta
  • Interleukin-6
  • Membrane Proteins
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • NLRC4 protein, human
  • NLRP1 protein, human
  • NLRP3 protein, human
  • RNA, Double-Stranded
  • anthrax toxin
  • Rotenone
  • Uric Acid
  • Adenosine Triphosphate
  • eIF-2 Kinase