ESRRA-ATG5-Mediated mitophagy enhances arginine metabolism to alleviate diabetic kidney disease

Diabetic kidney disease (DKD) is increasingly recognized as a consequence of impaired mitochondrial quality control in renal tubular epithelial cells (TECs). In this study we show that the nuclear receptor ESRRA (estrogen related receptor alpha) transcriptionally activates ATG5 (autophagy related 5) to sustain PINK1 (PTEN induced kinase 1)-dependent mitophagy and preserve tubular homeostasis. ESRRA and ATG5 expression were markedly reduced in human DKD biopsies, and their abundance correlated positively with estimated glomerular filtration rate and inversely with albuminuria. Conditional deletion of Esrra in mouse tubules or CRISPR-Cas9 knockout in primary TECs suppressed mitophagy, exacerbated mitochondrial dysfunction and aggravated tubulointerstitial fibrosis, whereas tubular Esrra re-expression or Atg5 overexpression restored mitophagy and attenuated renal injury. Multi-omics and mechanistic assays identified the natural polyphenol salvianolic acid C (SAC) as a high-affinity ESRRA agonist that binds Asp326, Phe382 and Ala396, stabilizes the receptor and upregulates ATG5. SAC dose-dependently improved proteinuria, renal function, mitochondrial respiration and insulin sensitivity in db/db and high-fat diet-streptozotocin DKD models without overt toxicity. Metabolomic profiling revealed that ESRRA-ATG5-driven mitophagy targets ARG2 (arginase 2) for autophagy-lysosomal degradation, thereby shifting L-arginine flux from urea production toward nitric-oxide synthesis; exogenous L-arginine partly rescued renal injury in Esrra-deficient mice. Collectively, this study uncovers an ESRRA-ATG5 axis that couples selective mitophagy to L-arginine metabolism as a pivotal defense against DKD, and identifies SAC as a first-in-class, naturally derived ESRRA activator with therapeutic potential.