Chemotherapy drugs induce pyroptosis through caspase-3 cleavage of a gasdermin

Abstract

Pyroptosis is a form of cell death that is critical for immunity. It can be induced by the canonical caspase-1 inflammasomes or by activation of caspase-4, -5 and -11 by cytosolic lipopolysaccharide. The caspases cleave gasdermin D (GSDMD) in its middle linker to release autoinhibition on its gasdermin-N domain, which executes pyroptosis via its pore-forming activity. GSDMD belongs to a gasdermin family that shares the pore-forming domain. The functions and mechanisms of activation of other gasdermins are unknown. Here we show that GSDME, which was originally identified as DFNA5 (deafness, autosomal dominant 5), can switch caspase-3-mediated apoptosis induced by TNF or chemotherapy drugs to pyroptosis. GSDME was specifically cleaved by caspase-3 in its linker, generating a GSDME-N fragment that perforates membranes and thereby induces pyroptosis. After chemotherapy, cleavage of GSDME by caspase-3 induced pyroptosis in certain GSDME-expressing cancer cells. GSDME was silenced in most cancer cells but expressed in many normal tissues. Human primary cells exhibited GSDME-dependent pyroptosis upon activation of caspase-3 by chemotherapy drugs. Gsdme (also known as Dfna5) mice were protected from chemotherapy-induced tissue damage and weight loss. These findings suggest that caspase-3 activation can trigger necrosis by cleaving GSDME and offer new insights into cancer chemotherapy.

Gasdermins: Effectors of Pyroptosis

“…Gasdermin D is a member of a family of conserved proteins that includes gasdermin A, B, C, D, E, and DFNB59[9,10] (Table 1), most of which have now been shown to have pore-forming activity. Previously, gasdermin E and DFNB59 were proposed to be excluded from the gasdermin family, and instead called gasdermin-related proteins[11], however we prefer to simplify the nomenclature by including all six genes in a single gasdermin family, given recent advances[12,13]. Most family members maintain the same domain structure with significant similarity between the pore forming domain and repressor domain, but divergent linkers[10].…”

“…Because this protein can form a pore and induce pyroptosis, Wang et al proposed to rename it gasdermin E[13], and we adopt this nomenclature here. GSDME is expressed in placenta, brain, heart, kidney, cochlea, intestines, and IgE-primed mast cells[9,37].…”

“…All known mutations in GSDME associated with deafness are characterized by skipping of exon 8, resulting in frameshifts and the formation of truncated gasdermin E protein[64–66]. The truncated RD fails to repress the PFD, resulting in a gain-of-function[13]. Knocking out GSDME in mice does not result in deafness[68].…”

“…Caspase-3 was recently shown to specifically cleave gasdermin E, which then forms pores in the plasma membrane and triggers lytic cell death in response to caspase-3 activators such as chemotherapeutic drugs, TNF, and viral infection[12,13]. It was proposed that gasdermin E is the effector of secondary necrosis[12]; that is lysis of apoptotic cells after prolonged time if apoptotic cells are not efferocytosed.…”

“…It was proposed that gasdermin E is the effector of secondary necrosis[12]; that is lysis of apoptotic cells after prolonged time if apoptotic cells are not efferocytosed. However, a recent study demonstrated that only specific cells express gasdermin E, and proposed that in such cells caspase-3 activation is switched from driving an apoptotic program to causing pyroptosis[13]. Thus, certain cells are programmed to undergo pyroptosis instead of apoptosis.…”