Targeting KLF4 degradation by doxycycline restores peroxisome lipid metabolism and mitochondrial energy production in acute kidney injury.

Acute kidney injury (AKI) is a life‑threatening condition with limited preventive medications. While the transcription factor Krüppel-like factor 4 (KLF4) is critical to AKI pathophysiology, its underlying molecular mechanisms remain incompletely understood. This study investigates KLF4 from a metabolic perspective and explores the renoprotective potential of doxycycline, an FDA-approved antibiotic. In murine models of ischemia‑reperfusion (IR)‑ and cisplatin (CDDP)‑induced AKI, doxycycline administered significantly attenuated kidney injury and protected renal tubular cells from glucose deprivation- and oxygen‑glucose deprivation-induced stress in vitro. Integrative transcriptomic and metabolomic profiling revealed that AKI progression involves profound metabolic dysfunction, characterized by the downregulation of peroxisomal Acyl-CoA oxidase 3 (ACOX3) and mitochondrial Isocitrate dehydrogenase 2 (IDH2). We identified KLF4 as a dual transcriptional repressor of ACOX3 and IDH2. Mechanistically, molecular docking, surface plasmon resonance, and co-immunoprecipitation assays demonstrated that doxycycline directly binds KLF4 and promotes its ubiquitin-mediated degradation via the E3 ligase FBXO32, which restores ACOX3/IDH2-mediated fatty acid oxidation and the TCA cycle, enhancing cellular resilience against ischemic crisis. These findings define a novel KLF4‑ACOX3/IDH2 metabolic axis and highlight doxycycline as a promising repositioning candidate for AKI prevention.