Project description:We identified RIOK2 as a FADD-interacting protein that is essential for caspase-8-dependent cleavage of GSDMD. RIOK2’s ATPase activity drives the transport of lysosome to ER through activating myosin II and thereby translocate FADD-RIPK1-caspase-8 complex from lysosome to ER. Importantly, RIOK2’s ATPase activity also promotes the association of RIOK2 with FADD–RIPK1–caspase-8 complex and directly activates cleavage of caspase-8 and GSDMD both at ER and in vitro.
Project description:We identified RIOK2 as a FADD-interacting protein that is essential for caspase-8-dependent cleavage of GSDMD. RIOK2’s ATPase activity drives the transport of lysosome to ER through activating myosin II and thereby translocate FADD-RIPK1-caspase-8 complex from lysosome to ER. Importantly, RIOK2’s ATPase activity also promotes the association of RIOK2 with FADD–RIPK1–caspase-8 complex and directly activates cleavage of caspase-8 and GSDMD both at ER and in vitro.
Project description:The process of pyroptosis is mediated by inflammasomes and a downstream effector known as gasdermin D (GSDMD). Upon cleavage by inflammasome-associated caspases, the N-terminal domain of GSDMD forms membrane pores that promote cytolysis. Numerous proteins promote GSDMD cleavage, but none are known to be required for pore formation after GSDMD cleavage. Herein, we report a forward genetic screen that identified the Ragulator-Rag complex as being necessary for GSDMD pore formation and pyroptosis in macrophages. Mechanistic analysis revealed that Ragulator-Rag is not required for GSDMD cleavage upon inflammasome activation, but rather promotes GSDMD oligomerization in the plasma membrane. Defects in GSDMD oligomerization and pore formation can be rescued by mitochondrial poisons that stimulate reactive oxygen species (ROS) production, and ROS modulation impacts the ability of inflammasome pathways to promote pore formation downstream of GSDMD cleavage. These findings reveal an unexpected link between key regulators of immunity (inflammasome-GSDMD) and metabolism (Ragulator-Rag).
Project description:Ethylene gas is essential for many developmental processes and stress responses in plants. ETHYLENE INSENSITIVE2 (EIN2), an NRAMP-homologous integral membrane protein, plays an essential role in ethylene signaling but its function remains enigmatic. Here we report that phosphorylation-regulated proteolytic processing of EIN2 triggers its endoplasmic reticulum (ER)-nucleus translocation, which is essential for hormone signaling and response in Arabidopsis. Without ethylene, or in hormone receptors mutants, ER-tethered EIN2 shows CTR1 kinase-dependent phosphorylation. Ethylene exposure triggers dephosphorylation and proteolytic cleavage, resulting in rapid nuclear translocation of a carboxyl-terminal EIN2 fragment (C’). Plants containing mutations that mimic EIN2 dephosphorylation, or inactivate CTR1, show constitutive cleavage and nuclear localization of EIN2-C’, and EIN3/EIL1-dependent activation of ethylene responses. These findings uncover a mechanism of subcellular communication whereby ethylene gas stimulates rapid phosphorylation-dependent cleavage and nuclear movement of the EIN2-C’ peptide, thus linking hormone perception and signaling components located in the ER with nuclear-localized transcriptional regulators.
Project description:Gasdermin D (GSDMD) is the executioner of pyroptosis, which is important for host defense against pathogen infection. After activation, caspase-mediated cleavage of GSDMD liberates an N-terminal fragment (GSDMD-NT), which oligomerizes and forms pores in the plasma membrane, leading to cell death and subsequent release of proinflammatory cytokines. How this process is spatiotemporally controlled to promote pyroptosis in cells has been a fundamental, unaddressed question. Here, we identify GSDMD as a substrate for reversible S-palmitoylation on cysteine 192 (Cys192) in response to lipopolysaccharide (LPS) stimulation. We found that the palmitoyl acyltransferase DHHC7palmitoylates GSDMD to direct its cleavage by caspases in pyroptosis by promoting the interaction of GSDMD and caspases. We further show that after GSDMD cleavage, palmitoylation of GSDMD-NTpromotes its plasma membrane translocation and binding, and then acyl protein thioesterase 2 (APT2) depalmitoylates GSDMD-NT to unmask the Cys192 residue to promote oxidation-mediated oligomerization and pyroptosis. Perturbation of either palmitoylation or depalmitoylation suppresses pyroptosis, extends the survival of mice from LPS-induced lethal septic shock and sensitizes mice to bacterial infection. Thus. our findings reveal a model through which a palmitoylation-depalmitoylationrelay spatially and temporally controls GSDMD activation in pyroptosis.
Project description:Gasdermin D (GSDMD) is the executioner of pyroptosis, which is important for host defense against pathogen infection. After activation, caspase-mediated cleavage of GSDMD liberates an N-terminal fragment (GSDMD-NT), which oligomerizes and forms pores in the plasma membrane, leading to cell death and subsequent release of proinflammatory cytokines. How this process is spatiotemporally controlled to promote pyroptosis in cells has been a fundamental, unaddressed question. Here, we identify GSDMD as a substrate for reversible S-palmitoylation on cysteine 192 (Cys192) in response to lipopolysaccharide (LPS) stimulation. We found that the palmitoyl acyltransferase DHHC7palmitoylates GSDMD to direct its cleavage by caspases in pyroptosis by promoting the interaction of GSDMD and caspases. We further show that after GSDMD cleavage, palmitoylation of GSDMD-NTpromotes its plasma membrane translocation and binding, and then acyl protein thioesterase 2 (APT2) depalmitoylates GSDMD-NT to unmask the Cys192 residue to promote oxidation-mediated oligomerization and pyroptosis. Perturbation of either palmitoylation or depalmitoylation suppresses pyroptosis, extends the survival of mice from LPS-induced lethal septic shock and sensitizes mice to bacterial infection. Thus. our findings reveal a model through which a palmitoylation-depalmitoylationrelay spatially and temporally controls GSDMD activation in pyroptosis.
Project description:We report that the atypical Kinase RIOK2 binds to transcription start sites, 5'UTR regions and promoters of a variety of genes, and the genome binding patterns of RIOK2 are analogous to that of bona-fide transcription factors.
Project description:Gasdermin D (GSDMD)-mediated macrophage pyroptosis plays a critical role in inflammation and host defense. Plasma membrane perforation elicited by caspase-cleaved GSDMD N-terminal domain (GSDMD-NT) triggers membrane rupture and subsequent pyroptotic cell death, resulting in release of pro-inflammatory IL-1β and IL-18. Here, using a proteomics approach, we identified fatty acid synthase (FASN) as a GSDMD-binding partner and demonstrated that post-translational palmitoylation of GSDMD at Cys191/Cys192 (human/mouse) led to membrane translocation of GSDMD-NT but not full-length GSDMD. Collectively, we establish GSDMD-NT palmitoylation as a key regulatory mechanism modulating immune activity in infectious and inflammatory diseases.
Project description:Chemotherapy is often combined with immune checkpoint inhibitor (ICI) to enhance immunotherapy responses. Despite the approval of chemo-immunotherapy in multiple human cancers including triple-negative breast cancer (TNBC), immunologically cold tumors remain largely unresponsive due to weak chemotherapy-stimulated immune responses. The mechanisms determining the immunogenicity of chemotherapy in immunologically cold tumors remain largely unknown. Here, we identify the endoplasmic reticulum (ER) stress sensor IRE1α as a critical checkpoint that restricts the immunogenicity of taxane chemotherapy and prevents the innate immune recognition of immunologically cold TNBC. IRE1α RNase silences chemotherapy-induced double-stranded RNA (dsRNA) through RIDD (Regulated IRE1-Dependent Decay) to prevent NLRP3 inflammasome–dependent pyroptosis. Inhibition of IRE1α RNase activity with a selective RNase inhibitor ORIN1001, currently in Phase I clinical trial, allows taxane chemotherapy to induce extensive dsRNA accumulation and activate NLRP3 inflammasome–dependent gasdermin D (GSDMD) cleavage. This triggers pyroptosis and a highly effective immune response in immunologically cold TNBC.
Project description:Gasdermin-D (GSDMD) is cleaved by caspase-1/4/11 in response to canonical and non-canonical inflammasome activation. Upon cleavage, GSDMD oligomerizes and forms membrane pores, resulting in IL-1β secretion, pyroptotic cell death and inflammatory pathologies including periodic fever syndromes and septic shock â a plague on modern medicine. The transcriptional machinery that drives the expression of GSDMD is unknown. Here we show that IRF2, a member of the interferon-regulatory factor (IRF) family, is essential for the transcriptional activation of GSDMD. A forward genetic screen with ethyl-N-nitrosourea (ENU)-mutagenized mice unequivocally linked IRF2 to inflammasome signaling. Indeed, GSDMD transcript levels were highly attenuated in Irf2â/â macrophages upon Irf2 deficiency in macrophages, endothelial cells, and multiple organs, corresponding to attenuated IL-1β secretion and inhibited pyroptosis. Mechanistically, IRF2 binds a previously uncharacterized site within the GSDMD promoter to directly drive GSDMD transcription for execution of pyroptosis in response to canonical and non-canonical inflammasome activation. Our data illuminate a prominent transcriptional mechanism for the expression of GSDMD, a key mediator of inflammatory pathologies.