Single-cell transcriptome analysis highlights a critical role of ATG5 for endothelial cells in diabetic nephropathy

This study analyzed diabetic nephropathy (DN)-related single-cell RNA sequencing (scRNA-seq) data from public databases and dissected the mechanism by which the sirtuin 1 (SIRT1)/autophagy-related 5 (ATG5) axis mediates high glucose (HG)-induced human renal glomerular endothelial cell (HRGEC) injury. The endothelium cluster was analyzed with DN-related scRNA-seq data (GSE131882 and GSE264268). HG-induced HRGEC injury was assessed by detecting cell viability, LDH release, apoptosis, EMT, and autophagy. SRT1720 was used to activate SIRT1 in cell models and STZ-induced mouse models. Renal dysfunction and pathological injury were assessed by detecting urinary albumin, serum creatinine, and BUN levels and performing histopathological staining (H&E, PAS, Masson, and TUNEL). Analysis of the endothelium cluster discovered that the autophagy pathway in the endothelial cluster was suppressed in early-stage DN patients and mice. Moreover, HG induced cell apoptosis and EMT in HRGECs, along with elevated acetylated levels of ATG5 and decreased protein levels of ATG5. SRT1720 decreased apoptosis, EMT, and elevated autophagic flux in HG-induced HRGECs, as well as improved renal function and histopathological changes, reduced EMT, and elevated autophagy in DN mouse models. However, Atg5 silencing reversed SRT1720-mediated alterations in these parameters. The SIRT1/ATG5 axis-dependent HRGEC autophagy restoration exerts a protective effect on the kidney during DN, offering a scientific ground for developing therapeutic strategies for DN based on autophagy regulation.