Matrine suppresses advanced glycation end products-induced human coronary smooth muscle cells phenotype conversion by regulating endoplasmic reticulum stress-dependent Notch signaling

Advanced glycation end products (AGEs) induce vascular smooth muscle cells (VSMCs) contractile-synthetic phenotypic conversion which plays roles in aggravated atherosclerosis in diabetes. Matrine has been proved to suppress AGEs-induced phenotypic conversion which is governed by Notch pathway. Endoplasmic reticulum stress was associated with Notch pathway. Cultured human coronary smooth muscle cells (HCSMCs) were incubated with AGE-BSA at 0, 5 and 10 μmol/l. Specific siRNA was used to silence Protein kinase RNA-like ER kinase (PERK). Matrine at 0, 0.5 and 1.0 mmol/l were used to pre-treat the cells. Immunofluorescent staining of Smooth muscle myosin heavy chain 11 (MYH11) and smooth muscle α-actin 2 (ACTA2) were used to identify the contractile phenotype of HCSMCs. Protein phosphorylation and expression levels were evaluated by Western Blotting. AGE-BSA exposure facilitated the contractile-synthetic phenotypic conversion of HCSMCs in a concentration-dependent manner. AGE-BSA exposure increased expression levels of glucose-regulated protein 78 (GRP78), Delta-like 4 (Dll4), Notch intracellular domain (NICD1), Hes family basic helix-loop-helix (bHLH) transcriptional factor 1 (HES1), as well as the phosphorylation level of PERK. Specific perk-siRNA transfection dramatically lowered PERK phosphorylation and resulted in down-regulation of Dll4, NICD1 and HES1 in HCSMCs exposed to AGE-BSA. Pre-treatment of matrine suppressed AGE-BSA-induced phenotypic conversion of HCSMCs in a concentration-dependent manner. Moreover, matrine pre-treatment reduced expression level of GRP78, NICD1, HES1 and the phosphrylation level of PERK in AGE-BSA-exposed HCSMCs in a concentration-dependent manner. These results suggested that matrine suppressed AGE-BSA-induced HCSMCs phenotypic conversion via attenuating ER stress PERK signaling-dependent Dll4- Notch pathway activation.