Liu Yingcun, Fu Yuqing, Xue Xin, Tang Gang, Si Liangyi
Department of Cardiology, The Third Affiliated Hospital, Chongqing Medical University, Chongqing 401120, P.R. China.
Department of Cardiology, The Eighth Affiliated Hospital, Sun Yat-sen University, Shenzhen, Guangdong 518000, P.R. China.
Exp Ther Med. 2023 Oct 4;26(5):542. doi: 10.3892/etm.2023.12241. eCollection 2023 Nov.
Myocardial ischemia-reperfusion (I/R) injury is a common complication of acute myocardial infarction following percutaneous coronary intervention, but there are currently no effective pharmacological targets for adjuvant therapy due to a lack of knowledge of I/R injury mechanisms in cardiomyocytes. To evaluate the effects of hypoxia-reoxygenation on the plasma proteome of cardiomyocytes and prospective therapeutic targets, five sets of H9C2 cardiomyocytes from rats were cultured under various hypoxic circumstances. Using Cell Counting Kit-8 (CCK8) and lactose dehydrogenase (LDH) release assays, the cell viability and LDH release of H9C2 cells were analyzed. Proteome sequencing was then performed on cardiomyocytes to show the quantitative protein changes during the I/R injury process. After hypoxia/reoxygenation, bromodomain-containing protein 2 (BRD2) expression was evaluated. After administering the BRD2 inhibitor dBET1, the expression of nuclear factor erythroid 2-related factor 2/haem oxygenase-1 (Nrf2/HO-1) was identified. The results showed that in the group exposed to 4 h of hypoxia followed by 4 h of reoxygenation (H/R4), the cell survival rate was dramatically reduced, although the apoptotic rate and LDH were much higher than in the normal oxygen group. In addition, the expressions of 2,325 proteins differed considerably between these two groups, with 128 upregulated and 122 downregulated proteins being discovered in the H/R4 group. After 4 h of reoxygenation, the BRD2 expression was increased. Following the addition of dBET1 to suppress BRD2, the expression of Nrf2/HO-1 was reduced, but the rate of apoptosis increased. In conclusion, through the Nrf2/HO-1 signaling pathway, BRD2 protects cardiomyocytes from damage caused by hypoxia/reoxygenation. This may have implications for novel treatment targets to minimize I/R damage to the myocardium.
心肌缺血再灌注（I/R）损伤是经皮冠状动脉介入治疗后急性心肌梗死的常见并发症，但由于对心肌细胞I/R损伤机制缺乏了解，目前尚无有效的辅助治疗药理学靶点。为了评估缺氧复氧对心肌细胞血浆蛋白质组的影响以及潜在的治疗靶点，将五组大鼠H9C2心肌细胞置于不同的缺氧环境中培养。使用细胞计数试剂盒-8（CCK8）和乳酸脱氢酶（LDH）释放试验分析H9C2细胞的细胞活力和LDH释放。然后对心肌细胞进行蛋白质组测序，以显示I/R损伤过程中的定量蛋白质变化。缺氧/复氧后，评估含溴结构域蛋白2（BRD2）的表达。给予BRD2抑制剂dBET1后，鉴定核因子红细胞2相关因子2/血红素加氧酶-1（Nrf2/HO-1）的表达。结果显示，在缺氧4小时后再复氧4小时（H/R4）的组中，细胞存活率显著降低，尽管凋亡率和LDH远高于正常氧组。此外，这两组之间有2325种蛋白质的表达存在显著差异，在H/R4组中发现128种蛋白质上调，122种蛋白质下调。复氧后BRD2表达增加。加入dBET1抑制BRD2后，Nrf2/HO-1的表达降低，但凋亡率增加。总之，BRD2通过Nrf2/HO-1信号通路保护心肌细胞免受缺氧/复氧损伤。这可能为尽量减少心肌I/R损伤的新治疗靶点提供启示。
