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)1,2,3,4,5. 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.

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Figure 1: Role of PKR in pyroptosis-mediated HMGB1 release.
Figure 2: PKR is important for inflammasome activation.
Figure 3: PKR physically interacts with NLRP3 and facilitates inflammasome activation.
Figure 4: PKR regulates NLRP1, AIM2 and NLRC4 inflammasome activation.


  1. 1

    Schroder, K. & Tschopp, J. The inflammasomes. Cell 140, 821–832 (2010)

  2. 2

    Ogura, Y., Sutterwala, F. S. & Flavell, R. A. The inflammasome: first line of the immune response to cell stress. Cell 126, 659–662 (2006)

  3. 3

    Lamkanfi, M. & Dixit, V. M. Modulation of inflammasome pathways by bacterial and viral pathogens. J. Immunol. 187, 597–602 (2011)

  4. 4

    Lamkanfi, M. et al. Inflammasome-dependent release of the alarmin HMGB1 in endotoxemia. J. Immunol. 185, 4385–4392 (2010)

  5. 5

    Kayagaki, N. et al. Non-canonical inflammasome activation targets caspase-11. Nature 479, 117–121 (2011)

  6. 6

    Andersson, U. & Tracey, K. J. HMGB1 is a therapeutic target for sterile inflammation and infection. Annu. Rev. Immunol. 29, 139–162 (2011)

  7. 7

    Yang, H. et al. A critical cysteine is required for HMGB1 binding to Toll-like receptor 4 and activation of macrophage cytokine release. Proc. Natl Acad. Sci. USA 107, 11942–11947 (2010)

  8. 8

    Manfredi, A. A. et al. Maturing dendritic cells depend on RAGE for in vivo homing to lymph nodes. J. Immunol. 180, 2270–2275 (2008)

  9. 9

    Willingham, S. B. et al. NLRP3 (NALP3, Cryopyrin) facilitates in vivo caspase-1 activation, necrosis, and HMGB1 release via inflammasome-dependent and -independent pathways. J. Immunol. 183, 2008–2015 (2009)

  10. 10

    Qin, S. et al. Role of HMGB1 in apoptosis-mediated sepsis lethality. J. Exp. Med. 203, 1637–1642 (2006)

  11. 11

    Jiang, W., Bell, C. W. & Pisetsky, D. S. The relationship between apoptosis and high-mobility group protein 1 release from murine macrophages stimulated with lipopolysaccharide or polyinosinic-polycytidylic acid. J. Immunol. 178, 6495–6503 (2007)

  12. 12

    Yanai, H. et al. HMGB proteins function as universal sentinels for nucleic-acid-mediated innate immune responses. Nature 462, 99–103 (2009)

  13. 13

    Dey, M. et al. Mechanistic link between PKR dimerization, autophosphorylation, and eIF2α substrate recognition. Cell 122, 901–913 (2005)

  14. 14

    Dar, A. C., Dever, T. E. & Sicheri, F. Higher-order substrate recognition of eIF2α by the RNA-dependent protein kinase PKR. Cell 122, 887–900 (2005)

  15. 15

    Hsu, L. C. et al. The protein kinase PKR is required for macrophage apoptosis after activation of Toll-like receptor 4. Nature 428, 341–345 (2004)

  16. 16

    Nakamura, T. et al. Double-stranded RNA-dependent protein kinase links pathogen sensing with stress and metabolic homeostasis. Cell 140, 338–348 (2010)

  17. 17

    Sander, L. E. et al. Detection of prokaryotic mRNA signifies microbial viability and promotes immunity. Nature 474, 385–389 (2011)

  18. 18

    Martinon, F., Pétrilli, V., Mayor, A., Tardivel, A. & Tschopp, J. Gout-associated uric acid crystals activate the NALP3 inflammasome. Nature 440, 237–241 (2006)

  19. 19

    Duncan, J. A. et al. Cryopyrin/NALP3 binds ATP/dATP, is an ATPase, and requires ATP binding to mediate inflammatory signaling. Proc. Natl Acad. Sci. USA 104, 8041–8046 (2007)

  20. 20

    Bennett, R. L. et al. RAX, the PKR activator, sensitizes cells to inflammatory cytokines, serum withdrawal, chemotherapy, and viral infection. Blood 108, 821–829 (2006)

  21. 21

    Rathinam, V. A., Vanaja, S. K. & Fitzgerald, K. A. Regulation of inflammasome signaling. Nature Immunol. 13, 333–342 (2012)

  22. 22

    Franchi, L., Muñoz-Planillo, R. & Núñez, G. Sensing and reacting to microbes through the inflammasomes. Nature Immunol. 13, 325–332 (2012)

  23. 23

    Schattgen, S. A. & Fitzgerald, K. A. The PYHIN protein family as mediators of host defenses. Immunol. Rev. 243, 109–118 (2011)

  24. 24

    Wen, H., Ting, J. P. & O’Neill, L. A. A role for the NLRP3 inflammasome in metabolic diseases—did Warburg miss inflammation? Nature Immunol. 13, 352–357 (2012)

  25. 25

    Strowig, T., Henao-Mejia, J., Elinav, E. & Flavell, R. Inflammasomes in health and disease. Nature 481, 278–286 (2012)

  26. 26

    Bauernfeind, F. et al. Cutting edge: reactive oxygen species inhibitors block priming, but not activation, of the NLRP3 inflammasome. J. Immunol. 187, 613–617 (2011)

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We thank H. LaQueta, M. Dancho, M. McCarty, E. Lau, D. Katz and J. Scheinerman for technical assistance. This work was supported in part by grants from the National Institutes of Health (RO1 GM62508 to K.J.T. and DK052539 to G.S.H.). B.L. and S.I.V.-F. are supported by the foundation of Elmezzi Graduate School of Molecular Medicine. T.N. is supported by fellowships from the International Human Frontier Science Program and a Career Development Award from the American Heart Association.

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B.L. and K.J.T. designed the research; B.L., T.N., K.I., D.J.A., J.L., Y.T., P.L., S.I.V.-F. and H.E.-H. performed the experiments; B.L., S.I.V.-F., P.S.O., H.Y., S.S.C., J.R., T.K., D.J.A., G.S.H., U.A. and K.J.T. analysed the results; J.P.-Y.T. and Y.Z. provided important reagents; B.L. made the figures; B.L. and K.J.T. wrote the paper; U.A., H.W., P.S.O., S.S.C. and G.S.H. edited and commented on the manuscripts.

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Correspondence to Ben Lu or Kevin J. Tracey.

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Lu, B., Nakamura, T., Inouye, K. et al. Novel role of PKR in inflammasome activation and HMGB1 release. Nature 488, 670–674 (2012).

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