AGE/RAGE Signaling in Diabetes-Mediated Vascular Calcification in Vascular Smooth Muscle Cells

摘要

Advanced Glycation End-Products (AGEs)/Receptor for AGEs (RAGE) signaling has been a well-studied cascade in different pathologies, particularly type Ⅱ diabetes mellitus. The complex nature of the receptor, ligand specificity, and intersecting pathways of AGE/RAGE signaling is still not well understood. AGE/RAGE signaling influences both cellular and systemic responses to increase bone matrix proteins through p38 MAPK and ERK1/2 signaling pathways in hyperglycemic and calcification conditions. AGE/RAGE signaling has also been shown to increase oxidative stress by promoting diabetes-mediated vascular calcification through NOX-1 activation and decreased SOD-2 expression to promote a phenotypic switch of vascular smooth muscle cells (VSMCs) to osteoblast-like cells. The purpose of this research is understand AGE/RAGE mediated vascular calcification as a complication of diabetes. Calcification was induced in primary mouse VSMCs of non-diabetic (Het~(RWT)), diabetic (db/db~(RWT)), non-diabetic RAGE knockout (Her~(RKD)), and diabetic RAGE knockout (db/db~(RKO)), and then subsequently treated with AGEs to activate RAGE. Intracellular calcium levels were quantified and showed a pronounced calcification in db/db~(RWT) and loss of RAGE resulted in a decrease in calcification in db/db~(RKO). Western blotting analysis revealed VSMC marker protein (a-smooth muscle actin) was decreased in db/db~(RWT) calcified cells indicating an osteoblast-like phenotypic switch and this was not observed in db/db~(RKO) VSMCs. These data demonstrated that RAGE has a role in diabetes-mediated vascular calcification. By understanding the role, the AGE/RAGE signaling cascade plays diabetes-mediated vascular calcification will allow for possible targets for pharmacological intervention to be identified that may decrease the severity of this diabetic complication.