Mechanism of HO-1 in alleviating sepsis-associated acute kidney injury via regulating mitochondrial proteostasis and targeted intervention with DNA nanomaterials

Abstract

Sepsis-associated acute kidney injury (S-AKI) is a major driver of systemic mortality and chronic renal dysfunction, yet effective mechanism-based interventions are lacking. Clinical analysis revealed significant oxidative stress imbalance in patients with S-AKI, characterized by reduced serum SOD activity and GSH levels. Here, we show that a mitochondria-protective proteostasis axis centered on Heme Oxygenase-1 (HO-1) preserves tubular epithelial homeostasis by stabilizing NDUFA6, a critical subunit of mitochondrial complex I. Using HO-1 based immunoprecipitation–mass spectrometry (IP–MS), we identified NDUFA6 as a high affinity HO-1 binding partner, and further investigation revealed LTN1 as an E3 ligase regulating NDUFA6 turnover. Mechanistically, HO-1 interacted with NDUFA6 and preserved its stability by attenuating LTN1-mediated K48-linked ubiquitination, whereas LTN1 promoted ubiquitin-dependent degradation of NDUFA6. To translate these findings into a therapeutic strategy, we engineered a hexahedral DNA nanocage (DNA cube) functionalized with G4/Hemin. This platform demonstrated robust physicochemical stability, renal-specific accumulation, and mitochondrial-associated localization. In both CLP-induced S-AKI models and lipopolysaccharide-challenged HK-2 cells, the G4/Hemin-DNA cube significantly ameliorated renal injury, suppressing inflammation, oxidative stress, and mitochondrial-mediated apoptosis. Notably, these therapeutic benefits were largely abolished by HO-1 knockdown. Our study establishes an essential role of the HO-1–LTN1–NDUFA6 proteostasis axis in mitochondrial integrity and introduces a targeted DNA-nanostructure-based strategy for targeted therapy in S-AKI.