USF2 EXACERBATES SEPSIS-INDUCED ACUTE KIDNEY INJURY AND FERROPTOSIS THROUGH LPCAT3-MEDIATED NRF2/HO-1/GPX4 PATHWAY.

Background: Sepsis-acute kidney injury (AKI) is a common complication in critically ill patients with a very high mortality rate. Lysophosphatidylcholine acyltransferase 3 (LPCAT3) is crucial in lipid metabolism; however, its role in the pathogenesis of sepsis-AKI remains unclear. Methods: Human renal tubular epithelial (HK2) cells stimulated with lipopolysaccharide (LPS) were used to establish sepsis-AKI cell models. Various assays, including cell counting kit 8, 5-ethynyl-2'-deoxyuridine staining, flow cytometry, and enzyme linked immunosorbent assay were employed to analyze the effects of LPS on HK2 cells. The levels of Fe 2+ , reactive oxygen species fluorescence intensity, and glutathione were measured to assess the impact of LPS on oxidative stress in HK2 cells. The expression of relevant genes was assessed by quantitative reverse transcription polymerase chain reaction and western blot. In terms of mechanism, the PROMO and JASPAR databases, chromatin immunoprecipitation assay, and dual luciferase reporter assay were engaged to predict and validate the transcriptional binding between upstream transcription factor 2 (USF2) and LPCAT3. In vivo experiments involved injecting adenovirus carrying Ad-sh-LPCAT3 via the tail vein to investigate the functional role of LPCAT3 in mice subjected to cecal ligation puncture-induced sepsis-AKI. Histological analyses were performed using hematoxylin and eosin staining, MASSON staining, and immunohistochemistry. Results: LPS inhibited the proliferation of HK2 cells while inducing apoptosis, inflammatory responses, and ferroptosis. LPCAT3 expression was upregulated in sepsis-AKI tissues and cells. Moreover, LPCAT3 knockdown weakened the sepsis-AKI in HK2 cells. Mechanistically, LPCAT3 was transcriptionally regulated by USF2, and LPCAT3 reversed the effects of si-USF2 in sepsis-AKI cell models via the nuclear factor erythroid 2-related factor 2/heme oxygenase-1/glutathione peroxidase 4 (NRF2/HO-1/GPX4) pathway. Mouse experiments demonstrated that LPCAT3 intensified sepsis-AKI through the same molecular mechanism in vivo . Conclusion: USF2 knockdown resulted in the downregulation of LPCAT3, thereby modulating the NRF2/HO-1/GPX4 pathway and aggravating sepsis-AKI and ferroptosis.