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

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.

<p>Caspase-3 Promotes Diabetic Kidney Disease Through Gasdermin E-Mediated Progression to Secondary Necrosis During Apoptosis</p>

“…A recent study pointed out that GSDME augments the activation of the mitochondrial apoptotic pathway via forming pores in the mitochondria to facilitate cytochrome c release. 33 Other superfamily members, like GSDMA and GSDMD, seem to share the ability to augment the apoptotic pathway through mitochondria. 33,34 Therefore, more sophisticated experiments are required to further clarify the role of GSDME in DKD.…”

Inflammasome‐associated cell death: Pyroptosis, apoptosis, and physiological implications

“…However, it is important to note that the apoptotic and GSDMD-mediated pyroptotic pathways activate each other or operate simultaneously under certain conditions. [36][37][38]76 (b) The amount of GSDMD pores will be influenced by the expression level of GSDMD, degree of caspase-1 activation, and regulatory mechanisms that control pyroptosis. GSDMD pores cause pyroptosis, through which the plasma membrane is perforated, leading to the robust release of IL-1β.…”

“…However, a previous study demonstrated that GSDMD-dependent caspase-3 activation occurred in macrophages several hours after the cytoplasmic delivery of LPS and suggested that GSDMD promoted caspase-3 activation by facilitating the release of cytochrome c from mitochondria. 76 GSDMD p30 binds to cardiolipin and other phospholipids that are localized in mitochondrial membranes, which enables this pore-forming protein to permeabilize mitochondria, leading to cytochrome c release. 34,35 However, based on the essential role of small apoptosis mediators, ATP/dATP and cytochrome c, in the formation of apoptosomes, the apoptosome pathway unexpectedly continued to operate after pyroptosis.…”

“…34,35 However, based on the essential role of small apoptosis mediators, ATP/dATP and cytochrome c, in the formation of apoptosomes, the apoptosome pathway unexpectedly continued to operate after pyroptosis. 76 One possible explanation for this is that even if the plasma membrane is perforated by GSDMD, small amounts of ATP/dATP and cytochrome c that persist in swollen pyroptotic cells may support the formation of apoptosomes; however, more time is needed than when the plasma membrane is intact. Therefore, in cells expressing sufficiently high levels of GSDMD to induce pyroptosis, GSDMD p30 not only appears to mediate pyroptosis, but also inhibits the activation of caspase-3 soon after caspase-1 activation, thereby ensuring the induction of pyroptosis.…”

Accelerating functional gene discovery in osteoarthritis

“…Gasdermin E is a member of a family of proteins that facilitate necrotic programmed cell death (pyroptosis) following cleavage by caspase-3 56 . Pyroptosis has recently been shown to promote knee osteoarthritis 57,58 , and upregulation of Gsdme in high-grade osteoarthritis cartilage ( Figure 5), supports a role for gasdermin E in disease progression.…”