Novel role of PKR in inflammasome activation and HMGB1 release.
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.
Laboratory of Biomedical Science, The Feinstein Institute for Medical Research, 350 Community Drive, Manhasset, New York 11030, USA. blu@nshs.edu
Ben
B
Lu
Takahisa
T
Nakamura
Karen
K
Inouye
Jianhua
J
Li
Yiting
Y
Tang
Peter
P
Lundbäck
Sergio I
SI
Valdes-Ferrer
Peder S
PS
Olofsson
Thomas
T
Kalb
Jesse
J
Roth
Yongrui
Y
Zou
Helena
H
Erlandsson-Harris
Huan
H
Yang
Jenny P-Y
JP
Ting
Haichao
H
Wang
Ulf
U
Andersson
Daniel J
DJ
Antoine
Sangeeta S
SS
Chavan
Gökhan S
GS
Hotamisligil
Kevin J
KJ
Tracey
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D000942:Antigens, Bacterial / Q000494:pharmacology; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001427:Bacterial Toxins / Q000494:pharmacology; D053468:CARD Signaling Adaptor Proteins / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D003459:Crystallins / Q000378:metabolism; D004926:Escherichia coli / Q000276:immunology / Q000502:physiology; D004927:Escherichia coli Infections / Q000276:immunology / Q000378:metabolism; D005260:Female; D024243:HMGB1 Protein / Q000097:blood / Q000378:metabolism*; D006801:Humans; D058847:Inflammasomes / Q000819:agonists / Q000378:metabolism*; D020382:Interleukin-18 / Q000097:blood; D053583:Interleukin-1beta / Q000097:blood; D015850:Interleukin-6 / Q000032:analysis / Q000097:blood; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D000070576:NLR Proteins; D010538:Peritonitis / Q000378:metabolism; D010766:Phosphorylation; D012330:RNA, Double-Stranded / Q000276:immunology / Q000494:pharmacology; D012402:Rotenone / Q000494:pharmacology; D012480:Salmonella Infections / Q000276:immunology / Q000378:metabolism; D012486:Salmonella typhimurium / Q000276:immunology / Q000502:physiology; D014162:Transfection; D014527:Uric Acid / Q000494:pharmacology; D019892:eIF-2 Kinase / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D000942:Antigens, Bacterial; D051017:Apoptosis Regulatory Proteins; D001427:Bacterial Toxins; D053468:CARD Signaling Adaptor Proteins; C105445:CRYBG1 protein, human; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D003459:Crystallins; D024243:HMGB1 Protein; D058847:Inflammasomes; D020382:Interleukin-18; D053583:Interleukin-1beta; D015850:Interleukin-6; D008565:Membrane Proteins; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D000070576:NLR Proteins; C435692:NLRC4 protein, human; C427903:NLRP1 protein, human; C453881:NLRP3 protein, human; D012330:RNA, Double-Stranded; C030325:anthrax toxin; D012402:Rotenone; D014527:Uric Acid; D000255:Adenosine Triphosphate; D019892:eIF-2 Kinase