Project description:Through the RIP experiment, our group found lnc-RMRP was physically associated with Gli1 and exhibited enrichment in Gli1-activated LF cells. Histological studies revealed elevated expression of RMRP in hypertrophic LF. In vitro experiments further confirmed that RMRP promoted Gli1 SUMO modification and nucleus transfer. Mechanistically, RMRP induced GSDMD-mediated pyroptosis, proinflammatory activation, and collagen expression through the Hedgehog pathway. Notably, the mechanical stress-induced hypertrophy of LF in rabbit exhibited analogous pathological changes of LF fibrosis occurred in human and showed enhanced levels of collagen and α-SMA. Knockdown of RMRP resulted in the decreased expression of fibrosis and pyroptosis-related proteins, ultimately ameliorating fibrosis.
Project description:To identify the changes in gene expression profile caused by mechanical stress in the ligamentum flavum, we performed resection of the L3-4 supraspinal muscle and L2-3, L4-5 posterolateral fusion with instrumentation to concentrate the mechanical stress with segmental instability at the L3-4 level. The control group underwent only surgical exposure as a sham operation. Both groups of rabbits were sacrificed at 1 year after surgery and total RNA were extracted from ligamentum flavum.
Project description:To identify the changes in gene expression profile caused by mechanical stress in the ligamentum flavum, we performed resection of the L3-4 supraspinal muscle and L2-3, L4-5 posterolateral fusion with instrumentation to concentrate the mechanical stress with segmental instability at the L3-4 level. The control group underwent only surgical exposure as a sham operation. Both groups of rabbits were sacrificed at 16 weeks after surgery and total RNA were extracted from ligamentum flavum.
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:Lumbar spinal stenosis (LSS) represents a major global healthcare burden resulting in back pain and disorders of the limbs among the elderly population. The hypertrophy of ligamentum flavum (HLF), marked by fibrosis and inflammation, significantly contributes to LSS. Fibroblasts and endothelial cells are two important cells in the pathological process of ligamentum flavum (LF) fibrosis and inflammation. These two cells exhibit heterogeneity in various fibrotic diseases, yet their heterogeneity in LF fibrosis remains poorly defined. Using single-cell RNA-seq, we examined the alterations of fibroblasts, endothelial cells, and key genes in the hypertrophic LF, aiming to establish a comprehensive single-cell atlas of LF to identify high-priority targets for pharmaceutical treatment of LSS. Here, we find there are five distinct subpopulations of LF fibroblasts: secretory-papillary, secretory-reticular, mesenchymal, pro-inflammatory, and unknown. Importantly, in HLF, the proportion of mesenchymal fibroblast subpopulations increases significantly compared to normal LF (NLF), reflecting their close association with the pathogenesis of HLF. Furthermore, critical target genes that might be involved in HLF and fibrosis, such as MGP, ASPN, OGN, LUM, and CTSK, are identified. In addition, we also investigate the heterogeneity of endothelial cells and highlight the critical role of AECs subpopulation in LF fibrosis. This study will contribute to our understanding of the pathogenesis of HLF and offer possible targets for the treatment of fibrotic diseases.
Project description:The tumor immune microenvironment is complex in composition, function and dynamic, influencing the evolution of tumor, prognosis and response to immunotherapy. Recent studies have significantly advanced our knowledge of the roles of Gasdermin protein-mediated tumoral pyroptosis activated by caspases and granzymes from cytotoxic lymphocytes in facilitating the killing of tumor cells. However, the pyroptosis of immune cells in tumor microenvironment and their affecting the reprogram of the tumor microenvironment remains poorly understood. In this study, we find that Gasdermin D (GSDMD), among Gasdermin family proteins, is significantly positively correlated with the immune checkpoint signature, and inversely linked to the overall survival of cancer patients by the analysis with TCGA clinical data. Using conditional knockout of GSDMD together with immunofluorescence co-labeling and single-cell RNA sequencing (scRNA-seq), we demonstrate that GSDMD mainly on antigen-presenting cells (APCs) such as macrophages and dendritic cells (DCs) in tumor microenvironment, restrains anti-tumor immunity under the treatment of PD-L1 antibody. Loss of GSDMD in APCs enhanced Type I interferon-stimulated gene (ISG) program of such cells, which promotes antigen presentation of macrophages and DCs, and facilitates the production of CD8+ effector and functional T cell. We further demonstrate that GSDMD deficiency increases anti-tumor immunity in a cyclic GMP–AMP synthase (cGAS)-dependent manner. Moreover, pharmacological inhibition of GSDMD-mediated pyroptosis significantly improves anti-tumor immunity in combination with PD-L1 antibody immunotherapy. Together, our findings reveal an important role for GSDMD-mediated pyroptosis of APCs such as macrophages and DCs in regulating CD8+ T cell function and underscore the potential of GSDMD blockade in promoting anti-tumor immunity, which may help the development of cancer immunotherapy.
Project description:Emerging evidence demonstrates that pyroptosis has been implicated in the pathogenesis of asthma. GSDMD is the pyroptosis executioner. The mechanism of GSDMD in asthma remains unclear. The aim of this study was to elucidate the potential role of GSDMD in asthmatic airway inflammation and remodeling. First, we performed immunofluorescent staining and ELISA to detect the protein levels of N-GSDMD in the airway epithelium and IL-18, IL-1β in serum of both asthma patients and the healthy individuals. We demonstrated that N-GSDMD, IL-18, and IL-1β were significantly increased in mild asthma compared with that from the controls. Then, wild type and Gsdmd-knock out (Gsdmd-/-) mice were used to establish asthma model. We isolated primary macrophages and performed histopathological staining, ELISA, flow cytometry to define the roles of GSDMD in allergic airway inflammation and tissue remodeling in vivo. We observed that the production of N-GSDMD, IL-18, and IL-1β were enhanced in OVA-induced asthma mice model. The knockout of Gsdmd resulted in attenuated N-GSDMD, IL-18, and IL-1β production in both bronchoalveolar lavage fluid (BALF) and lung tissue in asthmatic mice. In addition, Gsdmd-deficiency mice exhibit a significantly reduction in airway inflammation and remodeling, which might be associated with reduced Th17 type inflammation response and M2 polarization. Third, we explored the underlying mechanism of GSDMD in asthma by bulk RNA-sequencing. We found GSDMD may improve asthmatic airway inflammation and remodeling through regulating macrophage adhesion and migration, and then lead to M2 polarization by targeting Notch signaling pathway. These findings demonstrated that GSDMD plays a critical role in the pathogenesis of allergic inflammation and tissue remodeling.
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.