Aucubin ameliorates diabetic kidney disease by restoring hGENCs autophagy through promoting phosphorylation of ATG4B protein

Aucubin is a major component of <i>Eucommia ulmoides</i>, a traditional Chinese medicine used to treat diabetic kidney disease (DKD). However, the protective effect and mechanism of action of aucubin in DKD remains unclear. In this study, we found that aucubin decreased proteinuria in a DKD mouse model and alleviated human glomerular endothelial cells (hGENCs) damage caused by high glucose (HG). We labeled and quantified the total proteome and phosphorylated proteome of hGENCs using mass spectrometry, and the subsequent direct-data-independent acquisition analysis results showed that ATG4B protein phosphorylation is a prospective target of aucubin. We found that aucubin increased the phosphorylation level of ATG4B, restored autophagy, and weakened endothelial-mesenchymal transformation to protect against DKD <i>in vivo</i> and <i>in vitro</i>. Importantly, specific deletion of p-ATG4B aggravated HG-induced damage and eliminated the effects of aucubin-mediated protection in hGENCs. In conclusion, our study demonstrated that aucubin has protective effects against HG-induced hGENCs injury and in a DKD mouse model by upregulating p-ATG4B levels and restoring autophagy. This establishes p-ATG4B as a potential target for delaying DKD progression.