Molecular Mechanism of the IRF1/NFE2L1-DT/ALKBH5/Cx43 Axis in Radiation-Induced Injury in Vascular Endothelial Cells...

Radiotherapy effectively eradicates tumor cells but can also trigger pyroptotic damage in vascular endothelial cells. This study investigates the role of interferon regulatory factor 1 (IRF1) in radiation-induced endothelial injury, aiming to provide mechanistic insights for optimizing radiotherapy. Human umbilical vein endothelial cells (HUVECs) were exposed to x-ray irradiation, after which cell viability, lactate dehydrogenase (LDH) release, γ-H2AX foci formation, and the expression of pyroptosis-associated proteins (NLRP3, Cleaved Caspase-1, GSDMD-N, IL-1β, IL-18) were assessed. Expression levels of IRF1, NFE2L1-DT, PELP1, ALKBH5, and Cx43 were quantified. Chromatin enrichment of IRF1 at the NFE2L1-DT promoter and IRF1-NFE2L1-DT interactions were examined, along with NFE2L1-DT or ALKBH5 binding to PELP1. The enrichment of m⁶A modifications on Cx43 transcripts was also evaluated. X-ray exposure reduced HUVEC viability, elevated LDH release, increased γ-H2AX foci, and upregulated IRF1, along with pyroptosis markers. Silencing IRF1 reversed these changes. Mechanistically, IRF1 directly bound to and increased NFE2L1-DT expression. NFE2L1-DT interacted with PELP1 to enhance the binding of PELP1 to and ALKBH5 mRNA, thus upregulating ALKBH5 expression. ALKBH5-mediated m⁶A demethylation subsequently downregulated Cx43 expression. Overexpression of NFE2L1-DT or ALKBH5, or silencing Cx43, attenuated the protective effects of IRF1 silencing against radiation-induced damage. These findings indicate that radiation-induced IRF1 upregulation leads to endothelial injury by promoting pyroptosis through the NFE2L1-DT/ALKBH5/Cx43 axis.