Cell death is not essential for caspase-1-mediated interleukin-1β activation and secretion

Cell Death Differ. 2016 Nov 1;23(11):1827-1838. doi: 10.1038/cdd.2016.69. Epub 2016 Jul 15.

Abstract

Caspase-1 cleaves and activates the pro-inflammatory cytokine interleukin-1 beta (IL-1β), yet the mechanism of IL-1β release and its dependence on cell death remains controversial. To address this issue, we generated a novel inflammasome independent system in which we directly activate caspase-1 by dimerization. In this system, caspase-1 dimerization induced the cleavage and secretion of IL-1β, which did not require processing of caspase-1 into its p20 and p10 subunits. Moreover, direct caspase-1 dimerization allowed caspase-1 activation of IL-1β to be separated from cell death. Specifically, we demonstrate at the single cell level that IL-1β can be released from live, metabolically active, cells following caspase-1 activation. In addition, we show that dimerized or endogenous caspase-8 can also directly cleave IL-1β into its biologically active form, in the absence of canonical inflammasome components. Therefore, cell death is not obligatory for the robust secretion of bioactive IL-1β.

MeSH terms

  • Animals
  • Caspase 1 / metabolism*
  • Caspase 8 / metabolism
  • Cell Death
  • Cell Survival
  • DNA Gyrase / metabolism
  • Embryo, Mammalian / cytology
  • Fibroblasts / cytology
  • Fibroblasts / metabolism
  • Inflammasomes / metabolism
  • Interleukin-1beta / metabolism*
  • Mice
  • Protein Multimerization
  • Recombinant Fusion Proteins / metabolism

Substances

  • Inflammasomes
  • Interleukin-1beta
  • Recombinant Fusion Proteins
  • Caspase 8
  • Caspase 1
  • DNA Gyrase