Activation of RAGE- dependent endoplasmic reticulum stress associates with exacerbated post- myocardial infarction ventricular arrhythmias in diabetes

Association between receptor for advanced glycation end products (RAGE) and post- myocardial infarction (MI) ventricular arrhythmias (VAs) in diabetes was investigated. Correlation between premature ventricular contractions (PVCs) and serum advanced glycation end products (AGEs) content was analyzed in a cohort consisted of 101 ST segment elevated MI (STEMI) patients. MI diabetic rats were treated with anti- receptor for AGE (RAGE) antibody. Electrocardiography was used to record VAs. Myocytes were isolated from adjacent area around infracted region. Immunofluorescent stains were used to evaluate association between FKBP12.6 (FK506-bindingprotein 12.6) and ryanodine receptor 2 (RyR2). Calcium sparks were evaluated by confocal microscope. Protein expression and phosphorylation were assessed by Western blotting. Calcineurin (CaN) enzymatic activity and RyR2 channel activity were also determined. In the cohort study, significantly increased amount of (PVCs) were found in STEMI patients with diabetes (P<0.05). Serum AGEs concentration was significantly positively correlated with PVCs amount in STEMI patients (r=0.416, P<0.001). Multivariate analysis showed serum AGEs concentration was independently and positively related to frequent PVCs (adjusted hazard ratio, 1.86; 95% CI, 1.09-3.18, P=0.022). In the animal study, increased glucose regulated protein 78 (GRP78) expression, protein kinase RNA-like ER kinase (PERK) phosphorylation, CaN enzymatic activity, FKBP12.6-RyR2 disassociation, RyR2 channel opening and endoplasmic reticulum (ER) calcium releasing were found in diabetic MI animals, which were attenuated by anti-RAGE antibody treatment. This RAGE blocking also significantly lowered the VAs amount in diabetic MI animals. Activation of RAGE- dependent ER stress- mediated PERK/CaN/RyR2 signaling participated in post-MI VAs in diabetes.