Renal microvascular damaged in diabetes mellitus with hyperlipidemia through the regulation of MAMs by PACS2 in endothelial cell

Abstract

Background: The prevalence of diabetic vascular complications is rapidly increasing, especially in the diabetes mellitus with hyperlipidemia. Consistent hyperglycemia and hyperlipidemia impairs microvascular, but lack of effective intervention target to prevention or reduced the risk of serious bad ending. Methods: A mouse model of diabetes combined with hyperlipidemia were established by STZ injection and high fat diet to observe the possible damage of HGHF to renal blood vessels include vascular permeability, fibrosis and subcellular structure. Then, we replicated an in vitro endothelial cell injury model treated by 30mm Glucose and 0.1mm palmitic acid to verify its main functional changes. Proteomics and metabolomics were used to explore the molecular mechanisms behind diabetic microvascular damage. The mechanisms were further verified at siRNA interference and transgenic knockout mice. Results: We found that renal vascular permeability impaired and fibrosis increased significantly in the stz+HFD mice. In human umbilical vein endothelial cells (HUVECs) treated with high glucose/high fat (HGHF), the number of mitochondrial-associated membranes (MAMs) and the expression of phosphofurin acidic cluster sorting protein 2 (PACS2) increased. In particular, gene manipulation of PACS2 altered endothelial cell MAMs. Knocking down PACS2 restored the barrier function of HUVECs. In vivo, knocking out PACS2 ameliorated the kidney injury in diabetic mice induced by streptozotocin and fed with high-fat diet for up to 20 weeks. PACS2-/- mice leaked less vascular Evan’s blue and improved glomerular fibrosis in the kidney tissue of hyperglycemia and hyperlipidemia mouse model. We further observed the reduction of fatty acid β-oxidation (FAO), CPT1α expression, and NADPH production in endothelial cells induced by HGHF. These changes in fatty acid metabolism were rescued by silencing PACS2, but were blocked by the FAO inhibitor, etomoxir. Conclusion: PACS2 impacts the metabolic response of endothelial cells to HGHF through MAMs. Loss of PACS2 expression reduces glomerular endothelial cells barrier injury, induced by VE-Cadherin internalized under HGHF. PACS2 play a metabolism and MAMs regulators in the vascular endothelial cells of diabetes with hyperlipidemia.