The PYRIN domain-only protein POP2 inhibits inflammasome priming and activation

Rojo A. Ratsimandresy, Lan H. Chu, Sonal Khare, Lucia De Almeida, Anu Gangopadhyay, Mohanalaxmi Indramohan, Alexander V. Misharin, David R. Greaves, Harris Perlman, Andrea Dorfleutner*, Christian Stehlik

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


Inflammasomes are protein platforms linking recognition of microbe, pathogen-associated and damage-associated molecular patterns by cytosolic sensory proteins to caspase-1 activation. Caspase-1 promotes pyroptotic cell death and the maturation and secretion of interleukin (IL)-1β and IL-18, which trigger inflammatory responses to clear infections and initiate wound-healing; however, excessive responses cause inflammatory disease. Inflammasome assembly requires the PYRIN domain (PYD)-containing adaptor ASC, and depends on PYD-PYD interactions. Here we show that the PYD-only protein POP2 inhibits inflammasome assembly by binding to ASC and interfering with the recruitment of ASC to upstream sensors, which prevents caspase-1 activation and cytokine release. POP2 also impairs macrophage priming by inhibiting the activation of non-canonical IκB kinase ϵ and IκBα, and consequently protects from excessive inflammation and acute shock in vivo. Our findings advance our understanding of the complex regulatory mechanisms that maintain a balanced inflammatory response and highlight important differences between individual POP members.

Original languageEnglish (US)
Article number15556
JournalNature communications
StatePublished - Jun 5 2017

ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)


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