Diabetes, Metabolic Syndrome and Obesity (Oct 2023)
Advanced Glycation End Products Downregulate Connexin 43 and Connexin 40 in Diabetic Atrial Myocytes via the AMPK Pathway
Abstract
Fan Yang,1,* Huan-Huan Liu,2,* Lei Zhang,1,* Xiao-Lu Zhang,1 Jie Zhang,1 Feng Li,1 Ning Zhao,2 Zhi-Yuan Zhang,1 Qi Kong,1 Xiao-Yu Liu,1 Ying Wu,1 Zhi-Ming Yu,1 Ling-Ling Qian,1 Ru-Xing Wang1,2 1Department of Cardiology, the Affiliated Wuxi People’s Hospital of Nanjing Medical University, Wuxi, 214023, People’s Republic of China; 2Wuxi School of Medicine, Jiangnan University, Wuxi, People’s Republic of China*These authors contributed equally to this workCorrespondence: Ling-Ling Qian; Ru-Xing Wang, Department of Cardiology, the Affiliated Wuxi People’s Hospital of Nanjing Medical University, Wuxi, 214023, People’s Republic of China, Tel +0086-510-85351593, Email [email protected]; [email protected]: Diabetes mellitus is an independent risk factor for atrial fibrillation (AF), which may be related to accumulation of advanced glycation end products (AGEs). However, the mechanisms involved are not completely clear. Abnormality of gap junction proteins, especially connexin 43 (Cx43) and connexin 40 (Cx40) in atrial myocytes, is an important cause of increased susceptibility of AF. The aim of our work is to investigate the mechanism of dysregulated Cx43 and Cx40 in atrial myocytes of diabetic rats.Methods: We established a type 1 diabetic rat model by intraperitoneal injection of streptozotocin. HL-1 cells and primary rat atrial myocytes were treated with AGEs in vitro. Using Western blotting, immunofluorescence staining, immunohistochemistry, and lucifer yellow diffusion measurements, we investigated dysregulation of Cx43 and Cx40 and its mechanism in atrial myocytes of diabetic rats.Results: Accumulation of AGEs was found in diabetic rats. The expression of Cx43 and Cx40 was reduced in the atrium of diabetic rats, accompanied by the decrease of phosphorylated Adenosine 5’-monophosphate-activated protein kinase (p-AMPK). Similar results were found in cultured HL-1 cells and primary rat atrial myocytes, suggesting a role of AGEs on gap junction proteins. An AMPK agonist, 5-Aminoimidazole-4-carboxamide ribonucleoside (AICAR), reversed the down-regulated Cx43 expression induced by AGEs stimulation. More importantly, lucifer yellow diffusion assay showed that AGEs significantly affected gap junctional function, and these changes were reversed by AICAR.Conclusion: Thus, we conclude that AGEs cause dysregulation of Cx43 and Cx40 in diabetic atria via the AMPK pathway, thereby leading to gap junction dysfunction, which may contribute to the increased AF susceptibility in diabetes.Keywords: diabetes, atrial fibrillation, advanced glycosylation end products, adenosine 5’-monophosphate-activated protein kinase, connexin
