B109-04 HMGN5 Orchestrates the P53-GPX4 Axis to Regulate Cell Fate Decisions in Injury

Rationale High mobility group protein 5 (HMGN5) binds nucleosomes and modulates chromatin accessibility, yet how chromatin remodeling influences epithelial cell fate during lung injury remains unclear. Cell cycle arrest and ferroptotic cell death are emerging mechanisms in chronic lung disease pathogenesis. We hypothesized that HMGN5 regulates epithelial cell fate decisions through modulation of the p53-GPX4 axis, thereby affecting susceptibility to ferroptosis and contributing to chronic obstructive pulmonary disease (COPD) progression. Methods We analyzed previously generated human and murine single-cell RNA-sequencing data to investigate epithelial cell states in vivo in both human and mouse. Two distinct populations of type II alveolar epithelial cells were identified based on surfactant protein C (SP-C) expression, Ki67 and HMGN5 expression, classified as activated and non-activated ATII cells. We characterized the HMGN5 knockout mouse and performed loss-of-function studies using siRNA-mediated knockdown of HMGN5 in lung epithelial cells and assessed cell cycle status, p53 signaling, and ferroptosis markers using flow cytometry, immunoblotting, and lipid peroxidation assays. Ferroptosis dependency was tested using pharmacological inhibitors. Epithelial-specific GPX4 knockout mice were used to evaluate the functional role of GPX4 in vivo following cigarette smoke exposure. Histological analysis, immunofluorescence, lung function testing as well as Precision cut lung slides were used to assess epithelial injury, ferroptosis, and COPD-like phenotypes. Results Reduced HMGN5 expression induced p53 activation and drove epithelial cell cycle arrest. Persistent elevation of p53 decreased glutathione peroxidase 4 (GPX4) expression, leading to increased lipid peroxidation and ferroptotic cell death. Ferroptosis inhibitors rescued epithelial cells from cell death, confirming dependency on GPX4 suppression. Alveolar epithelial-specific GPX4 deletion resulted in increased oxidative injury, heightened ferroptosis markers, and worsened airspace enlargement and lung function decline following cigarette smoke exposure, establishing GPX4 as a critical epithelial protector in COPD pathogenesis. Conclusion HMGN5 preserves epithelial homeostasis by maintaining a balanced p53-GPX4 axis, facilitating proper cell cycle progression, and preventing ferroptotic cell death. Loss of HMGN5 sensitizes epithelial cells to ferroptosis through p53-mediated GPX4 suppression, promoting epithelial injury and COPD progression. Targeting ferroptosis may provide therapeutic opportunities to protect epithelial integrity in chronic lung diseases. This abstract is funded by: German Federal Ministry of Education and Research (BMBF) program FERROPATH (01EJ2205B) to MC, AÖY and AJ. Additionally, MC, received funding from the European Research Council (ERC) under the European Unions’s Horzion 2020 research and innovation program (grant agreement No. GA 884754)