Gasdermin pores permeabilize mitochondria to augment caspase-3 activation during apoptosis and inflammasome activation

TLDR

Gasdermin E cleavage by caspase‑3 releases an N‑terminal domain that forms plasma‑membrane pores to trigger pyroptosis. We show that both GSDME‑N and GSDMD‑N permeabilize mitochondria, causing cytochrome‑c release and apoptosome activation, and that GSDME deficiency reduces these apoptotic signals and promotes cell growth, revealing gasdermins as mitochondrial amplifiers of apoptosis.

Abstract

Gasdermin E (GSDME/DFNA5) cleavage by caspase-3 liberates the GSDME-N domain, which mediates pyroptosis by forming pores in the plasma membrane. Here we show that GSDME-N also permeabilizes the mitochondrial membrane, releasing cytochrome c and activating the apoptosome. Cytochrome c release and caspase-3 activation in response to intrinsic and extrinsic apoptotic stimuli are significantly reduced in GSDME-deficient cells comparing with wild type cells. GSDME deficiency also accelerates cell growth in culture and in a mouse model of melanoma. Phosphomimetic mutation of the highly conserved phosphorylatable Thr6 residue of GSDME, inhibits its pore-forming activity, thus uncovering a potential mechanism by which GSDME might be regulated. Like GSDME-N, inflammasome-generated gasdermin D-N (GSDMD-N), can also permeabilize the mitochondria linking inflammasome activation to downstream activation of the apoptosome. Collectively, our results point to a role of gasdermin proteins in targeting the mitochondria to promote cytochrome c release to augment the mitochondrial apoptotic pathway.