O-GlcNAcylation attenuates ischemia-reperfusion–induced pulmonary epithelial cell ferroptosis via the Nrf2/G6PDH pathway
Ontology highlight
ABSTRACT: Lung ischemia-reperfusion (I/R) injury is a common clinical pathology associated with high mortality. The pathophysiology of lung I/R injury involves ferroptosis and elevated protein O-GlcNAcylation levels, while the effect of O-GlcNAcylation on lung I/R injury remains unclear. This research aimed to explore the effect of O-GlcNAcylation on reducing ferroptosis in pulmonary epithelial cells caused by I/R. First, we identified O-GlcNAc transferase 1 (Ogt1) as a differentially expressed gene in lung epithelial cells of acute lung injury/acute respiratory distress syndrome (ALI/ARDS) patients, using single-cell sequencing, and Gene Ontology analysis (GO analysis) revealed the enrichment of the ferroptosis process. We found a time-dependent dynamic alteration in lung O-GlcNAcylation during I/R injury. Proteomics analysis identified the differentially expressed proteins enriched in ferroptosis and multiple redox-related pathways based on KEGG annotation. Thus, we generated Ogt1-conditional knockout mice and found that Ogt1 deficiency aggravated ferroptosis, as evidenced by lipid reactive oxygen species (lipid ROS), malondialdehyde (MDA), Fe2+, as well as alterations in critical protein expression glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11). Consistently, we found that elevated O-GlcNAcylation inhibited ferroptosis sensitivity in hypoxia/reoxygenation (H/R) injury-induced TC-1 cells via O-GlcNAcylated NF-E2-related factor-2 (Nrf2). Furthermore, both the chromatin immunoprecipitation (ChIP) assay and the dual-luciferase reporter assay indicated that Nrf2 could bind with translation start site (TSS) of glucose-6-phosphate dehydrogenase (G6PDH) and promote its transcriptional activity. As an important rate-limiting enzyme in the pentose phosphate pathway (PPP), elevated G6PDH provided a mass of nicotinamide adenine dinucleotide phosphate (NADPH) to improve the redox state of glutathione (GSH) and eventually led to ferroptosis resistance. Rescue experiments proved that Nrf2 knockdown or Nrf2-T334A (O-GlcNAcylation site) mutation abolished the protective effect of ferroptosis resistance. In summary, we revealed that O-GlcNAcylation could protect against I/R lung injury by reducing ferroptosis sensitivity via the Nrf2/G6PDH pathway. Our work will provide a new basis for clinical therapeutic strategies for pulmonary ischemia-reperfusion-induced acute lung injury.
Project description:Primary graft dysfunction (PGD), which is caused primarily by ischemia–reperfusion injury (IRI), is a major obstacle in lung transplantation. Here, we developed an orthotopic, single-lung transplant pig model to simulate prolonged cold IRI. After 24 hours of cold ischemia and 8 hours of warm reperfusion, the transplanted lung exhibited severe allograft injury. Subsequent single-cell RNA sequencing (scRNA-seq) revealed significant changes in alveolar macrophages after IRI, with prominently enriched ferroptosis pathways. Transmission electron microscopy (TEM) confirmed characteristic ferroptosis changes in lung macrophages, and decreased GPX4 expression in macrophages indicated increased susceptibility to ferroptosis. Overall, our pig orthotopic left lung transplant model effectively simulates IRI after transplantation, which offers a valuable platform for more detailed investigations of early reperfusion injury to pulmonary grafts. Moreover, we preliminarily demonstrated the importance of macrophage ferroptosis in IRI, suggesting that inhibiting macrophage ferroptosis may be a promising therapeutic strategy for lung IRI.
Project description:Ferroptosis is an iron-dependent programmed cell death associated with severe kidney diseases, linked to decreased glutathione peroxidase 4 (GPX4). However, the spatial distribution of renal GPX4-mediated ferroptosis and the molecular events causing GPX4 reduction during ischemia-reperfusion (I/R) remain largely unknown. Using spatial transcriptomics, we identify that GPX4 is situated at the interface of the inner cortex and outer medulla, a hyperactive ferroptosis site post-I/R injury. We show that OTU deubiquitinase 5 (OTUD5) is a GPX4-binding protein that confers ferroptosis resistance by stabilizing GPX4. During I/R, ferroptosis is induced by mTORC1-mediated autophagy, causing OTUD5 degradation and subsequent GPX4 decay. Functionally, OTUD5 deletion intensifies renal tubular cell ferroptosis and exacerbates acute kidney injury, while AAV-mediated OTUD5 delivery mitigates ferroptosis and promotes renal function recovery from I/R injury. In this work, our study highlights a new autophagy-dependent ferroptosis module: hypoxia/ischemia-induced OTUD5 autophagy triggers GPX4 degradation, offering a potential therapeutic avenue for I/R-related kidney diseases.
Project description:Acute kidney injury (AKI) is a common and life-threatening condition associated with cell death, where ferroptosis plays a critical role. Chemerin, primarily produced in white adipose tissue, has multiple biological functions in renal pathophysiology. However, to date, whether and how chemerin regulates the progression of AKI remain unclear. Here, we found that chemerin expression was reduced in both AKI model mice and cells. Similarly, serum chemerin levels were also decreased in AKI patients. The administration of recombinant chemerin improves renal function in ischemia-reperfusion (I/R) model mice. Chemerin significantly attenuates ferroptosis in kidneys. In TCMK-1 cells, chemerin knockdown further aggravates ferroptosis. Mechanistically, chemerin activates AMP-activated protein kinase (AMPK), which induces the phosphorylation of nuclear factor erythroid 2-related factor 2 (NRF2) in renal tubular cells. Subsequently, NRF2 translocates into the nucleus, where it stimulates the expression of cystine/glutamate antiporter solute carrier (SLC7A11). As a result, cystine uptake and glutathione (GSH) biosynthesis in renal tubular cells were increased, which confers cells with higher capacity against ferroptosis. Overall, our findings indicate that chemerin plays a protective role in AKI by repressing ferroptosis in renal tubular cells, which is likely due to the activation in the AMPK/NRF2/SLC7A11 axis.
Project description:Heart disease remains the leading cause of death globally. Although reperfusion following myocardial ischemia can prevent death by restoring nutrient flow, ischemia/reperfusion injury can cause significant heart damage. The mechanisms that drive ischemia/reperfusion injury are not well understood; currently, few methods can predict the state of the cardiac muscle cell and its metabolic conditions during ischemia. Here, we explored the energetic sustainability of cardiomyocytes, using a model for cellular metabolism to predict the levels of ATP following hypoxia. We modeled glycolytic metabolism with a system of coupled ordinary differential equations describing the individual metabolic reactions within the cardiomyocyte over time. Reduced oxygen levels and ATP consumption rates were simulated to characterize metabolite responses to ischemia. By tracking biochemical species within the cell, our model enables prediction of the cell’s condition up to the moment of reperfusion. The simulations revealed a distinct transition between energetically sustainable and unsustainable ATP concentrations for various energetic demands. Our model illustrates how even low oxygen concentrations allow the cell to perform essential functions. We found that the oxygen level required for a sustainable level of ATP increases roughly linearly with the ATP consumption rate. An extracellular O2 concentration of ~0.007 mM could supply basic energy needs in non-beating cardiomyocytes, suggesting that increased collateral circulation may provide an important source of oxygen to sustain the cardiomyocyte during extended ischemia. Our model provides a time-dependent framework for studying various intervention strategies to change the outcome of reperfusion.
Project description:To examine the age-related vulnerability to lung ischemia reperfusion injury, pulmonary gene expression profiles after lung ischemia reperfusion were compared between young and old mice.
Project description:Characterized by lethal iron accumulation and lipid peroxidation, ferroptosis plays critical roles in liver injury, especially caused by ischemia/reperfusion (I/R) of hepatic inflow occlusion during liver operation. However, the lack of effective and safe clinical precautionary measure is still the main problem in preventing hepatic ferroptosis. Here, we found that the excessive production of reactive oxygen species could decrease the expression of Interferon (IFN)-stimulated gene DExH-box helicase 58 (DHX58) in hepatocytes, and then promote hepatic ferroptosis, while pre-treatment using IFN-α increased DHX58 expression and prevented ferroptosis during I/R injury. Mechanistically, DHX58 with RNA-binding activity could constitutively associate the mRNA of glutathione peroxidase 4 (GPX4), a crucial ferroptosis suppressor, and then recruit the m6A reader YT521-B homology domain containing 2 (YTHDC2) to promote the translation of Gpx4 mRNA in m6A-dependent manner, thus enhancing GPX4 protein level and preventing hepatic ferroptosis. Therefore, we provide mechanistic evidence for the IFN-stimulated DHX58 in promoting the translation of m6A-modified Gpx4 mRNA, and suggest the promising clinical potential of IFN-α pre-treatment in the prevention of hepatic ferroptosis.
Project description:Lung ischemia-reperfusion (I/R) injury remains one of the common complications after various cardiopulmonary surgeries. I-R injury represents one potentially maladaptive response of the innate immune system which is featured by an exacerbated sterile inflammatory response triggered by tissue damage. Thus, understanding the key components and processes involved in sterile inflammation during lung I-R injury is critical to alter care and extend survival for patients with acute lung injury. We constructed a minipig surgical model of transient unilateral left pulmonary artery occlusion without bronchial involvement to create ventilated lung I-R injury. Lung tissues from minipig with sham operation (one sample), left side lung tissues (the operated side)(one sample) and right side lung tissues (the non-operated side)(one sample) from minipig with lung ischemia-reperfusion were submitted for gene expression array analysis.
Project description:Ischemia reperfusion induced injury contributes to poor lung transplant outcomes.Microarrays were used to study the biological response of human lungs to the ischemia reperfusion process. Samples were collected from lung transplant cases at Toronto General Hospital. Lungs were donation after brain death (DBD)
Project description:Ischemia reperfusion induced injury contributes to poor lung transplant outcomes. We used microarrays to study the biological response of human lungs to the ischemia reperfusion process. Samples were collected from lung transplant cases at Toronto General Hospital. Lungs were donation after brain death (DBD)
Project description:Ischemia-reperfusion injury (IRI) is a major cause of morbidity and mortality following conventional lung transplantation and warm ischemia may limit success of transplanting lungs from non-heart-beating donors. We sought to determine alterations in gene expression in rat lung tissue subjected to warm ischemia in vivo followed by reperfusion. Keywords: time course