Yang Fan, Liu Huan-Huan, Zhang Lei, Zhang Xiao-Lu, Zhang Jie, Li Feng, Zhao Ning, Zhang Zhi-Yuan, Kong Qi, Liu Xiao-Yu, Wu Ying, Yu Zhi-Ming, Qian Ling-Ling, Wang Ru-Xing
Department of Cardiology, the Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi, 214023, People's Republic of China.
Wuxi School of Medicine, Jiangnan University, Wuxi, People's Republic of China.
Diabetes Metab Syndr Obes. 2023 Oct 2;16:3045-3056. doi: 10.2147/DMSO.S419189. eCollection 2023.
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.
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.
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.
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.
糖尿病是心房颤动（AF）的独立危险因素，这可能与晚期糖基化终产物（AGEs）的积累有关。然而，其中涉及的机制尚不完全清楚。心房肌细胞中缝隙连接蛋白异常，尤其是连接蛋白43（Cx43）和连接蛋白40（Cx40），是AF易感性增加的重要原因。我们研究的目的是探讨糖尿病大鼠心房肌细胞中Cx43和Cx40失调的机制。
通过腹腔注射链脲佐菌素建立1型糖尿病大鼠模型。HL-1细胞和原代大鼠心房肌细胞在体外接受AGEs处理。使用蛋白质免疫印迹法、免疫荧光染色、免疫组织化学和荧光黄扩散测量，我们研究了糖尿病大鼠心房肌细胞中Cx43和Cx40的失调及其机制。
在糖尿病大鼠中发现了AGEs的积累。糖尿病大鼠心房中Cx43和Cx40的表达降低，同时磷酸化腺苷5'-单磷酸激活蛋白激酶（p-AMPK）减少。在培养的HL-1细胞和原代大鼠心房肌细胞中也发现了类似结果，提示AGEs对缝隙连接蛋白有作用。一种AMPK激动剂，5-氨基咪唑-4-甲酰胺核苷（AICAR），逆转了AGEs刺激诱导的Cx43表达下调。更重要的是，荧光黄扩散试验表明AGEs显著影响缝隙连接功能，而这些变化被AICAR逆转。
因此，我们得出结论，AGEs通过AMPK途径导致糖尿病心房中Cx43和Cx40失调，从而导致缝隙连接功能障碍，这可能导致糖尿病中AF易感性增加。
