Tom70介导内皮细胞线粒体生物发生在低氧性肺动脉高压中的作用及机制研究

Pulmonary vascular endothelium dysfunction is an important pathogenic factor contributing to hypoxic pulmonary hypertension (HPH), but the exact mechanism is still not clear. Mitochondrial biogenesis, which can increase the number and function of mitochondria, is considered to be able to improve the function of pulmonary vascular endothelial cells after hypoxia. Recent researches showed that hypoxia could increase the expression of NRF-1 and TFAM in pulmonary vascular endothelial cells which are the key transcription factors of mitochondrial biogenesis. However, TFAM level inside mitochondria was reduced, and mitochondrial number and function decreased after hypoxia. Moreover, only Tom70 level was decreased significantly among the translocase of outer mitochondrial membrane after hypoxia. And the up-regulation of Tom70 could increase the TFAM level in the mitochondria of pulmonary vascular endothelial cells; improve the quantity and function of mitochondria. We hypothesized that hypoxia induced the decreased expression of Tom70 in pulmonary vascular endothelial cells, reduced the mitochondrial biogenesis-associated protein transporting into mitochondria, inhibited mitochondrial biogenesis, caused endothelial cell dysfunction, and prompted the formation of HPH. Therefore, the aim of our study is to investigate the effects of Tom70-mediated mitochondrial biogenesis in improving the function of pulmonary vascular endothelial cell and alleviating HPH in vivo and in vitro. This study will provide a new insight for the prevention and treatment of HPH.

肺血管内皮功能障碍是低氧性肺动脉高压（HPH）的重要致病因素，但确切机制不清。促进线粒体生物发生，即增加线粒体数量和功能，被认为可以改善低氧后肺血管内皮细胞功能，但目前缺乏有效策略。课题组前期研究发现，虽然低氧可以诱导肺血管内皮细胞线粒体生物发生关键转录因子NRF-1和TFAM表达增加，但线粒体内发挥作用的TFAM却减少，线粒体数量和功能降低；此外，低氧后线粒体外膜转位酶中Tom70水平较常氧时显著降低，上调Tom70可增加低氧后肺血管内皮细胞线粒体TFAM含量，改善线粒体数量和功能。因此我们推测，低氧诱导肺血管内皮细胞Tom70表达降低，减少线粒体生物发生蛋白线粒体转运，抑制线粒体生物发生，引起内皮细胞功能紊乱，形成HPH。综上所述，本课题拟在整体和细胞水平研究Tom70介导的线粒体生物发生在改善低氧后肺血管内皮细胞功能，减轻HPH中的作用及机制，为防治HPH提供新的干预靶点。

肺血管内皮功能障碍是低氧性肺动脉高压（HPH）的重要致病因素，但确切机制不清。促进线粒体生物发生，即增加线粒体数量和功能，被认为可以改善低氧后肺血管内皮细胞功能，但目前缺乏有效策略。虽然低氧可以诱导肺血管内皮细胞线粒体生物发生关键转录因子NRF-1和TFAM表达增加，但线粒体内发挥作用的TFAM却减少，线粒体数量和功能降低；此外，低氧后线粒体外膜转位酶中Tom70水平较常氧时显著降低，上调Tom70可增加低氧后肺血管内皮细胞线粒体TFAM含量，改善线粒体数量和功能。.本项目选择离体原代肺血管内皮细胞低氧和在体HPH模型，以Tom70为切入点，综合应用基因过表达、透射电镜等手段，阐明线粒体生物发生相关蛋白线粒体内转运异常，是低氧后肺血管内皮细胞线粒体生物发生通路受阻的关键机制，明确Tom70介导的线粒体生物发生在改善低氧后肺血管内皮细胞功能，降低肺血管结构重塑，减轻HPH中的重要作用。结果显示低氧可以诱导肺血管内皮细胞线粒体生物发生关键转录因子PGC-1α、NRF-1和TFAM表达增加，但线粒体内发挥作用的TFAM却减少，线粒体数量和功能降低；此外，低氧后线粒体外膜转位酶中Tom70水平较常氧时显著降低，上调Tom70可增加低氧后肺血管内皮细胞线粒体TFAM含量，上调线粒体数量和功能，最终改善内皮细胞功能，证实线粒体生物发生是调节肺血管内皮细胞功能的关键机制。.本研究为干预肺血管内皮细胞功能减轻HPH提供新的理论依据，也为预防和治疗HPH提供新的思路及新的干预靶点。