Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Novel role of PKR in inflammasome activation and HMGB1 release

Abstract

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.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

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.

Similar content being viewed by others

References

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

    Article  CAS  Google Scholar 

  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)

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  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)

    Article  ADS  CAS  Google Scholar 

  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)

    Article  CAS  Google Scholar 

  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)

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  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)

    Article  CAS  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  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)

    Article  CAS  Google Scholar 

  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)

    Article  ADS  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

  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)

    Article  ADS  CAS  Google Scholar 

  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)

    Article  ADS  CAS  Google Scholar 

  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)

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  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)

    Article  CAS  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

  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)

    Article  CAS  Google Scholar 

Download references

Acknowledgements

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.

Author information

Authors and Affiliations

Authors

Contributions

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.

Corresponding authors

Correspondence to Ben Lu or Kevin J. Tracey.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Figures 1-43 and Supplementary Methods. (PDF 4551 kb)

PowerPoint slides

Rights and permissions

Reprints and permissions

About this article

Cite this article

Lu, B., Nakamura, T., Inouye, K. et al. Novel role of PKR in inflammasome activation and HMGB1 release. Nature 488, 670–674 (2012). https://doi.org/10.1038/nature11290

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature11290

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing