Wen Chenghao, Jiang Yunfei, Chen Wen, Xu Yueyue, Chen Ganyi, Zhou Qiang, Liu Quan, Jiang Hongwei, Liu Yafeng, Cao Xu, Yao Yiwei, Zhang Ruoyu, Qiu Zhibing, Liu Shengchen
Department of Thoracic and Cardiovascular Surgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu 210006, P.R. China.
Department of Thoracic and Cardiovascular Surgery, Nanjing First Hospital, Southeast University, Nanjing, Jiangsu 210006, P.R. China.
Exp Ther Med. 2024 Jul 4;28(3):349. doi: 10.3892/etm.2024.12638. eCollection 2024 Sep.
Ischemic heart disease (IHD) remains a leading cause of mortalities worldwide, necessitating timely reperfusion to reduce acute mortality. Paradoxically, reperfusion can induce myocardial ischemia/reperfusion (I/R) injury, which is primarily characterized by mitochondrial dysfunction. Translocator protein (TSPO) participates in multiple cellular events; however, its role in IHD, especially in the process of myocardial I/R injury, has not been well determined. The aim of the present study was to investigate the functional role of TSPO in myocardial I/R injury and dissect the concomitant cellular events involved. This study utilized small interfering RNA (siRNA) technology to knock down TSPO expression. The I/R process was simulated using an anoxia/reoxygenation (A/R) model. The role of TSPO in H9c2 cardiomyocytes was assessed using various techniques, such as Western blotting, Flow cytometry, Reverse transcription-quantitative PCR (RT-qPCR), Immunofluorescence, Co-immunoprecipitation (co-IP) and similar methods. It was found that A/R markedly upregulated the expression of TSPO in cardiomyocytes. Inhibition of TSPO improved myocardial cell apoptosis and damage following A/R stimulation. Additionally, targeting TSPO alleviated mitochondrial damage, reduced mitochondrial ROS release and enhanced ATP synthesis following A/R stimulation. It was further confirmed that A/R stimulation induced a significant increase in the expression of pivotal markers [phosporylated-PKR-like ER kinase (PERK)/PERK, activating transcription factor 6 (ATF6) and inositol-requiring enzyme 1] involved in the adaptive unfolded protein response, which is accompanied by downstream signaling during endoplasmic reticulum (ER) stress. Notably, knockdown increased the expression of the aforementioned markers and, subsequently, TSPO was confirmed to interact with ATF6, suggesting that TSPO might play a role in ER stress during myocardial I/R injury. Finally, inhibition of TSPO upregulated mitophagy, as indicated by further decreases in P62 and increases in Parkin and PINK1 levels following A/R stimulation. Together, the results suggest that TSPO plays a multifaceted role in myocardial I/R injury. Understanding TSPO-induced cellular responses could inform targeted therapeutic strategies for patients with IHD.
缺血性心脏病（IHD）仍然是全球范围内主要的死亡原因，需要及时进行再灌注以降低急性死亡率。矛盾的是，再灌注可诱发心肌缺血/再灌注（I/R）损伤，其主要特征为线粒体功能障碍。转位蛋白（TSPO）参与多种细胞活动；然而，其在IHD中的作用，尤其是在心肌I/R损伤过程中的作用，尚未得到充分确定。本研究的目的是探讨TSPO在心肌I/R损伤中的功能作用，并剖析其中伴随的细胞事件。本研究利用小干扰RNA（siRNA）技术敲低TSPO表达。使用缺氧/复氧（A/R）模型模拟I/R过程。采用多种技术，如蛋白质免疫印迹法、流式细胞术、逆转录定量聚合酶链反应（RT-qPCR）、免疫荧光法、免疫共沉淀（co-IP）等类似方法，评估TSPO在H9c2心肌细胞中的作用。研究发现，A/R显著上调心肌细胞中TSPO的表达。抑制TSPO可改善A/R刺激后心肌细胞的凋亡和损伤。此外，靶向TSPO可减轻线粒体损伤，减少线粒体活性氧释放，并增强A/R刺激后的ATP合成。进一步证实，A/R刺激可导致参与适应性未折叠蛋白反应的关键标志物[磷酸化-PKR样内质网激酶（PERK）/PERK、活化转录因子6（ATF6）和肌醇需求酶1]的表达显著增加，这伴随着内质网（ER）应激期间的下游信号传导。值得注意的是，敲低可增加上述标志物的表达，随后证实TSPO与ATF6相互作用，表明TSPO可能在心肌I/R损伤期间的ER应激中发挥作用。最后，如A/R刺激后P62进一步降低以及Parkin和PINK1水平升高所示，抑制TSPO可上调线粒体自噬。总之，结果表明TSPO在心肌I/R损伤中发挥多方面作用。了解TSPO诱导的细胞反应可为IHD患者的靶向治疗策略提供依据。
