Diabetic cardiomyopathy is a well-recognized complication of diabetes, but its pathophysiology is unclear. We aimed to investigate the mechanisms underlying cardiac dysfunction in an elderly type 2 diabetic (T2DM) mouse model, using membrane proteomic analyses. Elderly mice were fed a high fat diet for 12 weeks to induce T2DM, and myocardial structure and function were assessed by echocardiography. Cardiomyocytes were isolated by Langendorff perfusion and subjected to iTRAQ-based quantitative membrane proteomic profiling, immunoblotting, and real-time quantitative reverse-transcriptase polymerase chain reaction. Compared to controls, elderly T2DM mice showed worse systolic function, more myocardial fibrosis and up-regulation of several heart failure markers (all p < 0.05). Cardiomyocyte membrane proteomic profiling revealed that 417 proteins had differential expressions related to perturbations in several biological processes in T2DM mice compared with the control. The most up-regulated proteins were involved in oxidative phosphorylation, whereas many down-regulated proteins were involved in cytoskeletal regulation. Differential protein expression correlated with myocardial systolic velocity by tissue Doppler. In addition, cardiomyocyte immunofluorescence staining showed greater disorganization of thick/parallel F-actin stress fibers and marked reduction in F-to-G-actin ratio in T2DM vs control (p < 0.05), which paralleled worsened myocardial systolic velocity. We concluded that cardiac contractile dysfunction in elderly T2DM mice was associated with impaired energetics and cytoskeletal disorganization.

中文翻译：

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老年饮食诱导的糖尿病小鼠能量受损和细胞骨架紊乱的膜蛋白质组学

糖尿病性心肌病是公认的糖尿病并发症，但其病理生理机制尚不清楚。我们旨在利用膜蛋白质组学分析调查老年2型糖尿病（T2DM）小鼠模型中心脏功能障碍的潜在机制。给高龄小鼠喂食高脂饮食12周以诱导T2DM，并通过超声心动图评估心肌的结构和功能。通过Langendorff灌注分离心肌细胞，并进行基于iTRAQ的定量膜蛋白质组分析，免疫印迹和实时定量逆转录酶聚合酶链反应。与对照组相比，老年T2DM小鼠的收缩功能更差，心肌纤维化更多，并且某些心力衰竭标志物上调（所有p<0.05）。心肌细胞膜蛋白质组学分析显示，与对照组相比，T2DM小鼠的417种蛋白质在几种生物学过程中具有与微扰相关的差异表达。上调最多的蛋白参与氧化磷酸化，而许多下调的蛋白则参与细胞骨架的调节。差异蛋白表达与组织多普勒相关的心肌收缩速度有关。此外，心肌细胞免疫荧光染色显示，与对照相比，T2DM中粗大/平行的F-肌动蛋白应力纤维的杂乱程度更大，F-G-肌动蛋白比率显着降低（p<0.05），这与恶化的心肌收缩速度平行。我们得出的结论是，老年T2DM小鼠的心脏收缩功能障碍与能量受损和细胞骨架紊乱有关。