Aldehyde dehydrogenase 2 attenuates renal injury through inhibiting CYP4A expression

Renal ischemia-reperfusion injury (IRI) is a prevalent clinical syndrome, yet its underlying pathogenesis remains largely unknown. Aldehyde dehydrogenase 2 (ALDH2), an enzyme responsible for detoxifying lipid aldehydes, has been suggested to play a protective role against IRI. In our study, we observed that Aldh2 knock-out C57BL/6 mice experienced more severe renal functional impairment following IRI. This was characterized by elevated levels of creatinine and blood urea nitrogen, as well as increased apoptosis. Proteomic analysis further revealed that ALDH2 deficiency significantly disrupted lipid metabolism, resulting in higher levels of the proinflammatory protein CYP4A and its metabolic byproduct, 20-HETE. This metabolic disruption exacerbated renal inflammation and triggered endoplasmic reticulum stress. However, we found that administration of the CYP4A inhibitor, HET0016, could ameliorate these effects. Mechanistically, we discovered that after IRI, ALDH2 translocates to the nucleus and interacts with nuclear receptor corepressor 1 (NCOR1) to repress Cyp4a transcription. ALDH2 specifically interacts with the N-terminal domain of NCOR1, which is responsible for its interaction with its E3 ligase SIAH2. This interaction inhibits the proteasome degradation of NCOR1, ultimately stabilizing the NCOR1 transcriptional repression complex. In summary, our research uncovers the role of ALDH2 in mitigating renal IRI by inhibiting 20-HETE synthesis through the transcriptional repression of Cyp4a.