The inflammasome is an innate immune signaling platform leading to caspase-1 activation, maturation of pro-inflammatory cytokines and cell death. Recognition of DNA within the host cytosol induces the formation of a large complex composed of the AIM2 receptor, the ASC adaptor and the caspase-1 effector. Francisella tularensis, the agent of tularemia, replicates within the host cytosol. The macrophage cytosolic surveillance system detects Francisella through the AIM2 inflammasome. Upon Francisella novicida infection, we observed a faster kinetics of AIM2 speck formation in ASCKO and Casp1KO as compared to WT macrophages. This observation was validated by a biochemical approach thus demonstrating for the first time the existence of a negative feedback loop controlled by ASC/caspase-1 that regulates AIM2 complex formation/stability. This regulatory mechanism acted before pyroptosis and required caspase-1 catalytic activity. Our data suggest that sublytic caspase-1 activity could delay the formation of stable AIM2 speck, an inflammasome complex associated with cell death. © 2013 Juruj, Lelogeais, Pierini, Perret, Py, Jamilloux, Broz, Ader, Faure and Henry.
CITATION STYLE
Juruj, C., Lelogeais, V., Pierini, R., Perret, M., Py, B. F., Jamilloux, Y., … Henry, T. (2013). Caspase-1 activity affects AIM2 speck formation/stability through a negative feedback loop. Frontiers in Cellular and Infection Microbiology, 4(APR). https://doi.org/10.3389/fcimb.2013.00014
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