AIMS/HYPOTHESIS Diabetic cardiomyopathy, characterised by increased oxidative damage and mitochondrial dysfunction, contributes to the increased risk of heart failure in individuals with diabetes. Considering that A-kinase anchoring protein 121 (AKAP1) is localised in the mitochondrial outer membrane and plays key roles in the regulation of mitochondrial function, this study aimed to investigate the role of AKAP1 in diabetic cardiomyopathy and explore its underlying mechanisms. METHODS Loss- and gain-of-function approaches were used to investigate the role of AKAP1 in diabetic cardiomyopathy. Streptozotocin (STZ) was injected into Akap1-knockout (Akap1-KO) mice and their wild-type (WT) littermates to induce diabetes. In addition, primary neonatal cardiomyocytes treated with high glucose were used as a cell model of diabetes. Cardiac function was assessed with echocardiography. Akap1 overexpression was conducted by injecting adeno-associated virus 9 carrying Akap1 (AAV9-Akap1). LC-MS/MS analysis and functional experiments were used to explore underlying molecular mechanisms. RESULTS AKAP1 was downregulated in the hearts of STZ-induced diabetic mouse models. Akap1-KO significantly aggravated cardiac dysfunction in the STZ-treated diabetic mice when compared with WT diabetic littermates, as evidenced by the left ventricular ejection fraction (LVEF; STZ-treated WT mice [WT/STZ] vs STZ-treated Akap1-KO mice [KO/STZ], 51.6% vs 41.6%). Mechanistically, Akap1 deficiency impaired mitochondrial respiratory function characterised by reduced ATP production. Additionally, Akap1 deficiency increased cardiomyocyte apoptosis via enhanced mitochondrial reactive oxygen species (ROS) production. Furthermore, immunoprecipitation and mass spectrometry analysis indicated that AKAP1 interacted with the NADH-ubiquinone oxidoreductase 75 kDa subunit (NDUFS1). Specifically, Akap1 deficiency inhibited complex I activity by preventing translocation of NDUFS1 from the cytosol to mitochondria. Akap1 deficiency was also related to decreased ATP production and enhanced mitochondrial ROS-related apoptosis. In contrast, restoration of AKAP1 expression in the hearts of STZ-treated diabetic mice promoted translocation of NDUFS1 to mitochondria and alleviated diabetic cardiomyopathy in the LVEF (WT/STZ injected with adeno-associated virus carrying gfp [AAV9-gfp] vs WT/STZ AAV9-Akap1, 52.4% vs 59.6%; KO/STZ AAV9-gfp vs KO/STZ AAV9-Akap1, 42.2% vs 57.6%). CONCLUSIONS/INTERPRETATION Our study provides the first evidence that Akap1 deficiency exacerbates diabetic cardiomyopathy by impeding mitochondrial translocation of NDUFS1 to induce mitochondrial dysfunction and cardiomyocyte apoptosis. Our findings suggest that Akap1 upregulation has therapeutic potential for myocardial injury in individuals with diabetes.

中文翻译：

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Akap1缺乏症通过NDUFS1介导的线粒体功能障碍和细胞凋亡加剧了小鼠糖尿病性心肌病。

目的/假设糖尿病性心肌病的特征在于氧化损伤和线粒体功能障碍的增加，导致糖尿病患者发生心力衰竭的风险增加。考虑到A激酶锚定蛋白121（AKAP1）位于线粒体外膜中，并在线粒体功能的调节中起关键作用，本研究旨在研究AKAP1在糖尿病性心肌病中的作用，并探讨其潜在机制。方法采用功能丧失和获得功能的方法来研究AKAP1在糖尿病性心肌病中的作用。将链脲佐菌素（STZ）注射到Akap1-knockout（Akap1-KO）小鼠及其野生型（WT）同窝小鼠中以诱发糖尿病。另外，用高糖治疗的原代新生儿心肌细胞被用作糖尿病的细胞模型。通过超声心动图评估心脏功能。通过注射携带Akap1（AAV9-Akap1）的腺相关病毒9来进行Akap1过表达。LC-MS / MS分析和功能实验用于探索潜在的分子机制。结果AKAP1在STZ诱导的糖尿病小鼠模型的心脏中被下调。与左室射血分数（LVEF； STZ治疗的WT小鼠[WT / STZ]对比STZ治疗的Akap1-KO小鼠相比），与WT糖尿病同窝仔相比，Akap1-KO显着加重了STZ治疗的糖尿病小鼠的心脏功能障碍。 [KO / STZ]，分别为51.6％和41.6％）。从机理上讲，Akap1缺乏会损害线粒体呼吸功能，其特征是ATP生成减少。另外，Akap1缺乏症通过增强线粒体活性氧（ROS）的产生来增加心肌细胞的凋亡。此外，免疫沉淀和质谱分析表明AKAP1与NADH-泛醌氧化还原酶75 kDa亚基（NDUFS1）相互作用。具体而言，Akap1缺乏症通过阻止NDUFS1从胞质溶胶转移到线粒体而抑制了复合物I的活性。Akap1缺乏症还与降低ATP产生和增强线粒体ROS相关凋亡有关。相比之下，STZ处理的糖尿病小鼠心脏中AKAP1表达的恢复促进了LVEF中NDUFS1向线粒体的转运，并减轻了糖尿病性心肌病（WT / STZ注射了携带gfp [AAV9-gfp]与WT / STZ的腺相关病毒） AAV9-Akap1，52.4％和59.6％； KO / STZ AAV9-gfp与KO / STZ AAV9-Akap1，42.2％和57.6％）。结论/解释我们的研究提供了第一个证据，即Akap1缺乏症通过阻止NDUFS1的线粒体易位引起线粒体功能障碍和心肌细胞凋亡而加剧了糖尿病性心肌病。我们的研究结果表明，Akap1上调具有治疗糖尿病个体心肌损伤的潜力。