Apaf-1 Pyroptosome Senses Mitochondrial Permeability Transition

Abstract

Caspase-4 directly senses and is activated by cytosolic LPS in conditions of pathogen infection. It is unclear whether and how caspase-4 detects host derived factors for triggering pyroptosis. Here we show that mitochondrial permeability transition (MPT) promotes the assembly of a protein complex comprised of Apaf-1 and caspase-4 (caspase-11 in mice)，defined herein as pyroptosome, for the execution of facilitated pyroptosis. MPT induced by bile acids and calcium overload, and specifically by an adenine nucleotide translocator 1 (ANT1) activator, triggered pyroptosome assembly. Different from the direct cleavage of GSDMD by LPS-activated caspase-4, caspase-4 activated in the Apaf-1 pyroptosome proceeds to cleave caspase-3 and thereby gasdermin E (GSDME) to induce pyroptosis. Caspase-11 initiated and GSDME executed pyroptosis underlies cholesteric liver failure. These findings identify Apaf-1 pyroptosome as a pivotal machinery for cells sensing MPT signals and may shed lights on understanding how cells execute pyroptosis under sterile conditions.