Txnip对慢性间歇低氧致血管内皮细胞线粒体依赖性凋亡的调节机制研究

The mechanistic study of obstructive sleep apnea hypopnea syndrome (OSAHS)-related cardiovascular injury has been becoming a hot issue in recent years. Chronic intermittent hypoxia (CIH)-induced oxidative stress plays a pivotal role in this pathophysiological process. Mitochondria are not only an important organelle generating oxidative stress, but also involved in the regulation of ROS generation and apoptosis. Thioredoxin-interacting protein (Txnip), as an important component of antioxidant system, acts not only as an inhibitor against the antioxidant and anti-apoptotic roles of thioredoxin (TRX), but also a direct regulator of ROS production via affecting aerobic respiration in mitochondria and aerobic/anaerobic metabolic switch. Studies on ischemia-reperfusion injury of myocardial cells suggested that Txnip promoted mitochondrial-dependent apoptosis. Our previous study also confirmed Txnip as a critical factor in CIH-induced cell injury. However, the mechanisms of Txnip-mediated mitochondrial dysfunction and apoptosis caused by oxidative stress (e.g. CIH) still remain unclear. Therefore, this research will lucubrate the underlying mechanism of Txnip in affecting mitochondrial functions and mitochondrial-dependent apoptosis by using animal and cellular vascular endothelial injury models under CIH .To explore the relationship between Txnip and mitochondrial apoptosis under CIH will be meaningful to clarify the specific mechanisms of OSAHS related cardiovascular complications, and provide the basis for further studies of targeted drug.

阻塞性睡眠呼吸暂停低通气综合征（OSAHS）致心血管损伤机制是近年研究热点。慢性间歇低氧（CIH）所致氧化应激为关键病理生理机制。线粒体是氧化应激发生的重要场所，参与ROS生成及凋亡调控。硫氧还蛋白交互作用蛋白（Txnip）为重要的氧化抗氧化复合体组份，其可抑制硫氧还蛋白（TRX）的抗氧化与抗凋亡作用，也可作用于线粒体，影响其有氧呼吸功能及有氧无氧代谢转换，调节ROS生成。针对缺血再灌注心肌细胞损伤的研究发现Txnip促进线粒体依赖性凋亡在损伤中的作用，我们前期研究也证实Txnip为CIH致细胞损伤关键因子。但是，氧化应激（如CIH）下Txnip如何引起线粒体功能障碍及调节凋亡尚不清楚。因此，本课题拟在CIH动物和细胞模型上，深入研究Txnip对血管内皮细胞线粒体功能及线粒体相关凋亡的影响及机制。对全面阐述OSAHS致心血管损伤机制具有重要意义，并为寻找相关治疗靶点及药物开发奠定基础。

阻塞性睡眠呼吸暂停低通气综合征（OSAHS）是心血管疾病的独立危险因素，慢性间歇低氧（CIH）所致内皮细胞损伤是OSAHS合并心血管疾病的始动环节。本研究应用CIH动物和细胞模型，探讨CIH致血管内皮损伤情况及相关机制，为进一步研究OSAHS相关心血管疾病靶向治疗提供研究基础。首先，我们采用CIH动物和细胞处理模型，观察CIH致主动脉损伤情况。结果发现实验组大鼠主动脉内皮层断裂，肌层纤维化明显，内皮细胞凋亡增加，血浆氧化应激水平增加；实验组细胞亦出现活力下降，凋亡率增加，氧化应激水平增加。随后，我们观察CIH下内皮细胞的线粒体功能变化。我们发现CIH致内皮细胞线粒体结构和功能变化，是线粒体依赖的细胞凋亡的基础，而线粒体保护剂可以改善CIH下内皮细胞的凋亡情况。最后，我们检测了Txnip蛋白水平，并利用基因敲除和过表达技术，观察Txnip影响线粒体的功能过程。我们发现，CIH下，Txnip表达量增高，Txnip转录本2过表达后，可增加内皮细胞的凋亡，加重线粒体结构改变，并引起线粒体功能障碍；Txnip敲除后，可以改善线粒体结构改变。因此，我们认为CIH可通过TXNIP转录本2介导线粒体功能障碍，导致致线粒体依赖的凋亡蛋白释放，引起内皮细胞的凋亡。总之，CIH下Txnip引起的内皮细胞线粒体结构和功能的改变，是内皮细胞凋亡的重要原因，这为OSAHS相关心血管并发症的药物治疗，提供新的研究思路和研究基础。