Hyperglycemia-Driven Inhibition of AMP-Activated Protein Kinase α2 Induces Diabetic Cardiomyopathy by Promoting Mitochondria-Associated Endoplasmic Reticulum Membranes In Vivo
Hyperglycemia-Driven Inhibition of AMP-Activated Protein Kinase α2 Induces Diabetic Cardiomyopathy by Promoting Mitochondria-Associated Endoplasmic Reticulum Membranes In Vivo
复制标题
高血糖抑制AMP活化蛋白激酶α2通过促进线粒体相关内质网膜诱导糖尿病心肌病
DOI：
10.1161/circulationaha.118.033552
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发表时间：
2019-04-16
期刊：
影响因子：
37.8
通讯作者：
Zou, Ming-Hui
中科院分区：
文献类型：
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作者：
Wu, Shengnan;Lu, Qiulun;Zou, Ming-Hui
背景：Fundc1（包含 FUN14 结构域 1）是一种线粒体外膜蛋白，对于线粒体自噬和线粒体相关内质网膜 (MAM) 非常重要。 Fundc1 和 MAM 在糖尿病心脏中的作用仍不清楚。因此，本研究的目的是确定糖尿病诱导的 Fundc1 表达是否可以增加 MAM 形成，以及破坏 MAM 形成是否可以改善糖尿病心脏功能。 方法：检测糖尿病患者和非糖尿病供体心脏中的 FUNDC1 水平。在暴露于高葡萄糖（HG，30 mmol/L d-葡萄糖 48 小时）的小鼠新生心肌细胞中，以及在链脲佐菌素治疗的心脏特异性 Fundc1 敲除小鼠和心脏特异性 Fundc1 敲除糖尿病秋田小鼠中，检查了 Fundc1 诱导的 MAM 水平以及线粒体和心脏功能。 结果：与非糖尿病患者的心脏组织相比，糖尿病患者心脏组织中的 FUNDC1 水平显着升高捐助者。 In cultured mouse neonatal cardiomyocytes, HG conditions increased levels of Fundc1, the inositol 1,4,5-trisphosphate type 2 receptor (Ip(3)r2), and MAMs. Fundc1 或 Ip(3)r2 的基因下调可抑制 MAM 形成，减少内质网-线粒体 Ca2+ 通量，并改善 HG 处理的心肌细胞中的线粒体功能。一致地，在暴露于正常葡萄糖（5.5 mmol/L d-葡萄糖）的心肌细胞中，Fundc1 的腺病毒过表达促进了 MAM 形成、线粒体 Ca2+ 增加和线粒体功能障碍。与非糖尿病对照相比，链脲佐菌素治疗的小鼠和秋田小鼠心脏中的 Fundc1、Ip(3)r2 和 MAM 水平显着升高。此外，与对照心脏相比，糖尿病显着增加了Fundc1和Ip(3)r2的免疫共沉淀。 Fundc1 与 Ip(3)r2 的结合抑制 Ip(3)r2 泛素化和蛋白酶体介导的降解。心肌细胞特异性 Fundc1 缺失消除了糖尿病诱导的 MAM 形成，防止线粒体 Ca2+ 增加、线粒体碎片和细胞凋亡，并改善线粒体功能和心脏功能。在小鼠新生心肌细胞中，HG 抑制 AMP 激活的蛋白激酶活性。此外，在 Prkaa2 敲除小鼠的心肌细胞中，Fundc1 的表达、MAM 形成和线粒体 Ca2+ 水平显着增加。最后，腺病毒过表达组成型活性突变体 AMP 激活蛋白激酶消除了 HG 诱导的 MAM 形成和线粒体功能障碍。 结论：我们得出结论，糖尿病抑制 AMP 激活蛋白激酶，启动 Fundc1 介导的 MAM 形成、线粒体功能障碍和心肌病，表明 AMP 激活蛋白激酶诱导的 Fundc1 抑制是治疗糖尿病心肌病的有效靶点。
BACKGROUND: Fundc1 (FUN14 domain containing 1), an outer mitochondrial membrane protein, is important for mitophagy and mitochondria-associated endoplasmic reticulum membranes (MAMs). The roles of Fundc1 and MAMs in diabetic hearts remain unknown. The aims of this study, therefore, were to determine whether the diabetes mellitus-induced Fundc1 expression could increase MAM formation, and whether disruption of MAM formation improves diabetic cardiac function.METHODS: Levels of FUNDC1 were examined in the hearts from diabetic patients and nondiabetic donors. Levels of Fundc1-induced MAMs and mitochondrial and heart function were examined in mouse neonatal cardiomyocytes exposed to high glucose (HG, 30 mmol/L d-glucose for 48 hours), and in streptozotocin-treated cardiac-specific Fundc1 knockout mice and cardiacspecific Fundc1 knockout diabetic Akita mice, as well.RESULTS: FUNDC1 levels were significantly elevated in cardiac tissues from diabetic patients in comparison with those from nondiabetic donors. In cultured mouse neonatal cardiomyocytes, HG conditions increased levels of Fundc1, the inositol 1,4,5-trisphosphate type 2 receptor (Ip(3)r2), and MAMs. Genetic downregulation of either Fundc1 or Ip(3)r2 inhibited MAM formation, reduced endoplasmic reticulum-mitochondrial Ca2+ flux, and improved mitochondrial function in HG-treated cardiomyocytes. Consistently, adenoviral overexpression of Fundc1 promoted MAM formation, mitochondrial Ca2+ increase, and mitochondrial dysfunction in cardiomyocytes exposed to normal glucose (5.5 mmol/L d-glucose). In comparison with nondiabetic controls, levels of Fundc1, Ip(3)r2, and MAMs were significantly increased in hearts from streptozotocin-treated mice and Akita mice. Furthermore, in comparison with control hearts, diabetes mellitus markedly increased coimmunoprecipitation of Fundc1 and Ip(3)r2. The binding of Fundc1 to Ip(3)r2 inhibits Ip(3)r2 ubiquitination and proteasome-mediated degradation. Cardiomyocyte-specific Fundc1 deletion ablated diabetes mellitus-induced MAM formation, prevented mitochondrial Ca2+ increase, mitochondrial fragmentation, and apoptosis with improved mitochondrial functional capacity and cardiac function. In mouse neonatal cardiomyocytes, HG suppressed AMP-activated protein kinase activity. Furthermore, in cardiomyocytes of Prkaa2 knockout mice, expression of Fundc1, MAM formation, and mitochondrial Ca2+ levels were significantly increased. Finally, adenoviral overexpression of a constitutively active mutant AMP-activated protein kinase ablated HG-induced MAM formation and mitochondrial dysfunction.CONCLUSIONS: We conclude that diabetes mellitus suppresses AMP-activated protein kinase, initiating Fundc1-mediated MAM formation, mitochondrial dysfunction, and cardiomyopathy, suggesting that AMP-activated protein kinase-induced Fundc1 suppression is a valid target to treat diabetic cardiomyopathy.