Apelin/APJ alleviates diabetic nephropathy by improving glomerular endothelial cells dysfunction via SIRT3‑KLF15

Glomerular basement membrane (GBM) thickening, the earliest morphological change of diabetic nephropathy (DN), is related to glomerular endothelial cells (GECs) dysfunction which increase extracellular matrix (ECM) synthesizing. Apelin, the endogenous ligand for apelin/apelin receptor (APJ), is reported to alleviate endothelial cell dysfunction in DN. Therefore, it was hypothesized that apelin/APJ reduced GBM thickening by decreasing the synthesis of ECM in GECs. The results showed that apelin reduced glomerular fibrosis and GBM thickening by decreasing the expression of laminin and collagen IV in diabetic mice, which were cancelled following APJ knockout in GECs. Furthermore, apelin/APJ inhibited the synthesis of laminin and collagen IV in GECs by increasing the expression and activity of SIRT3, which promoted KLF15 deacetylation and translocation into nucleus. In conclusion, apelin/APJ reduced GBM thickening in diabetes mellitus by preventing laminin and collagen IV synthesizing via SIRT3‑KLF15 pathway in GECs.