Department of Cardiology, Shiyan Taihe Hospital (Hubei University of Medicine), Shiyan, China.
Department of Respiratory, Shiyan Taihe Hospital (Hubei University of Medicine), Shiyan, China.
ESC Heart Fail. 2023 Aug;10(4):2510-2523. doi: 10.1002/ehf2.14404. Epub 2023 Jun 8.
Diabetic cardiomyopathy (DC) is one of serious complications of diabetic patients. This study investigated the biological function of activating transcription factor 4 (ATF4) in DC.
Streptozotocin-treated mice and high glucose (HG)-exposed HL-1 cells were used as the in vivo and in vitro models of DC. Myocardial infarction (MI) was induced by left coronary artery ligation in mice. Cardiac functional parameters were detected by echocardiography. Target molecule expression was determined by real time quantitative PCR and western blotting. Cardiac fibrosis was observed by haematoxylin and eosin and Masson's staining. Cardiac apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labelling. Activities of superoxide dismutase, glutathione peroxidase, and levels of malonic dialdehyde and reactive oxygen species were used to assess oxidative stress damage. Molecular mechanisms were evaluated by chromatin immunoprecipitation, dual luciferase assay, and co-immunoprecipitation. ATF4 was up-regulated in the DC and MI mice (P < 0.01). Down-regulation of ATF4 improved cardiac function as evidenced by changes in cardiac functional parameters (P < 0.01), inhibited myocardial collagen I (P < 0.001) and collagen III (P < 0.001) expression, apoptosis (P < 0.001), and oxidative stress (P < 0.001) in diabetic mice. Collagen I (P < 0.01) and collagen III (P < 0.01) expression was increased in MI mice, which was reversed by ATF4 silencing (P < 0.05). ATF4 depletion enhanced viability (P < 0.01), repressed apoptosis (P < 0.001), oxidative damage (P < 0.001), and collagen I (P < 0.001), and collagen III (P < 0.001) expression of HG-stimulated HL-1 cells. ATF4 transcriptionally activated Smad ubiquitin regulatory factor 2 (Smurf2, P < 0.001) to promote ubiquitination and degradation of homeodomain interacting protein kinase-2 (P < 0.001) and subsequently caused inactivation of nuclear factor erythroid 2-related factor 2/heme oxygenase 1 pathway (P < 0.001). The inhibitory effects of ATF4 silencing on HG-induced apoptosis (P < 0.01), oxidative injury (P < 0.01), collagen I (P < 0.001), and collagen III (P < 0.001) expression were reversed by Smurf2 overexpression.
ATF4 facilitates diabetic cardiac fibrosis and oxidative stress by promoting Smurf2-mediated ubiquitination and degradation of homeodomain interacting protein kinase-2 and then inactivation of nuclear factor erythroid 2-related factor 2/heme oxygenase 1 pathway, suggesting ATF4 as a treatment target for DC.
糖尿病心肌病（DC）是糖尿病患者的严重并发症之一。本研究旨在探讨激活转录因子 4（ATF4）在 DC 中的生物学功能。
链脲佐菌素（STZ）处理的小鼠和高糖（HG）暴露的 HL-1 细胞被用作 DC 的体内和体外模型。通过左冠状动脉结扎诱导小鼠心肌梗死（MI）。通过超声心动图检测心脏功能参数。通过实时定量 PCR 和 Western blot 测定靶分子表达。通过苏木精和伊红以及 Masson 染色观察心肌纤维化。通过末端脱氧核苷酸转移酶 dUTP 缺口末端标记法评估心脏细胞凋亡。超氧化物歧化酶、谷胱甘肽过氧化物酶的活性以及丙二醛和活性氧水平用于评估氧化应激损伤。通过染色质免疫沉淀、双荧光素酶报告基因检测和共免疫沉淀评估分子机制。DC 和 MI 小鼠中 ATF4 表达上调（P<0.01）。下调 ATF4 可改善心脏功能，表现为心脏功能参数的变化（P<0.01），抑制糖尿病小鼠心肌胶原 I（P<0.001）和胶原 III（P<0.001）表达、凋亡（P<0.001）和氧化应激（P<0.001）。MI 小鼠的胶原 I（P<0.01）和胶原 III（P<0.01）表达增加，而 ATF4 沉默可逆转这种情况（P<0.05）。ATF4 耗竭可增强细胞活力（P<0.01），抑制细胞凋亡（P<0.001）、氧化损伤（P<0.001）以及 HG 刺激的 HL-1 细胞中胶原 I（P<0.001）和胶原 III（P<0.001）的表达。ATF4 转录激活 Smad 泛素调节因子 2（Smurf2，P<0.001），以促进同源结构域相互作用蛋白激酶 2（homeodomain interacting protein kinase-2，HIPK2）的泛素化和降解，从而使核因子红细胞 2 相关因子 2/血红素加氧酶 1 通路失活（P<0.001）。Smurf2 过表达逆转了 ATF4 沉默对 HG 诱导的细胞凋亡（P<0.01）、氧化损伤（P<0.01）、胶原 I（P<0.001）和胶原 III（P<0.001）表达的抑制作用。
ATF4 通过促进 Smurf2 介导的 HIPK2 泛素化和降解，从而使核因子红细胞 2 相关因子 2/血红素加氧酶 1 通路失活，促进糖尿病性心脏纤维化和氧化应激，提示 ATF4 可作为 DC 的治疗靶点。
