龙牙楤木皂苷调控线粒体融和分裂平衡抗心肌缺血再灌注损伤的分子机制研究

Mitochondrial dysfunction plays a key role in the pathogenesis of myocardial ischemia-reperfusion injury (MIRI). Recent experimental data suggest that manipulating mitochondrial dynamics (fission and fusion), may affect the altered mitochondrial tubular networks within the cell, providing novel therapeutic targets for the treatment of MIRI. Aralia elata (Miq) Seem, which belongs to Araliaceae family, has the effects of supplementing Qi and promoting blood circulation. Continuous studies mainly on its cardioprotective effects have been carried out in our laboratory since 1980s. We found its novel use for the treatment of coronary heart disease, which has obtained Drug Clinical Trial Approval Document (Number 2003L01111) from the state Food and Drug Administration (SFDA). Recently, we for the first time found that Elatoside C and Araloside C, the major triterpenoid compounds isolated from A. elata, could inhibit I/R-induced mitochondrial injury by maintained mitochondrial membrane potential, diminished mitochondrial ROS, and reduced mitochondrial apoptosis pathway, which indicate that the cardioprotective activities of total saponins and its active components may be closely associated with preservation of mitochondrial integrity and function. The present study aims to investigate whether the underlying mechanisms of cardioprotective effects of Aralia elata triterpenoid compounds are dependent on regulation of mitochondrial fission and fusion proteins and other related signal transduction proteins, thereby inhibiting mitochondrial dysfunction and subsequent cell death during I/R. The present study may provide a novel target and a novel insight for developing new drugs for MIRI and theoretical basis for clinical application of Aralia elata saponins.

线粒体损伤是导致心肌缺血再灌注损伤(MIRI)的关键因素。线粒体融合分裂的动态平衡对维持线粒体结构功能至关重要。以调控线粒体融合分裂为靶点的旨在减轻线粒体功能障碍的药物发现是防治MIRI的新策略。龙牙楤木系五加科楤木属植物，具有益气活血的功效。我们从80年代即开始了对龙牙楤木的研究，发现了其总皂苷治疗冠心病、心绞痛的新用途，已获临床批件。我们近期研究发现龙牙楤木皂苷类成分Elatoside C和Araloside C能维持线粒体膜电位稳定，抑制心肌细胞线粒体凋亡通路，发挥抗I/R作用。提示龙牙楤木皂苷类成分的抗MIRI的保护作用与稳定线粒体结构功能密切相关。本课题拟在前期工作基础上，从线粒体动力学角度，研究龙牙楤木皂苷类活性成分通过调控线粒体融和分裂蛋白表达、抑制线粒体功能损伤，进而介导心肌缺血再灌注损伤的保护机理，确证其作用的信号通路与靶分子，精确定位对疾病治疗的相关靶点。

以调控线粒体融合分裂为靶点的旨在减轻线粒体功能障碍的药物发现是防治心肌缺血/再灌注损伤（MIRI）的新策略。本项目分别利用结扎大鼠左冠状动脉前降支造成心肌缺血再灌损伤模型、H9c2心肌细胞、乳鼠原代心肌细胞、人源干细胞诱导心肌细胞缺氧复氧模型，发现并确证龙牙楤木单体皂苷去葡萄糖竹节参皂苷Iva（CE）对心肌缺血再灌注损伤具有显著的保护作用。提示CE可能成为治疗冠心病的潜在候选药物。进一步从线粒体动力学的角度探索龙牙楤木皂苷类成分保护心肌缺血再灌注损伤的分子机制研究发现，CE能够通过调控AMPK信号通路，促进线粒体融合蛋白OPA1表达，维持线粒体功能，抑制线粒体凋亡途径从而减轻心肌缺血再灌损伤。提示调控AMPK-OPA1信号通路可能是其抗心肌缺血再灌的潜在靶点。为以线粒体融和-分裂为基础研制开发防治心肌缺血再灌注损伤新药提供了实验依据。另外，实验结果发现Araloside (AsC)对心肌缺血损伤具有显著的保护作用，能够减轻由缺血损伤引起的心肌细胞氧化应激，改善心肌能量代谢，维持线粒体功能。其机制与调控AMPK信号通路,减少心肌细胞凋亡有关。本项目的研究结果提示CE和AsC有望成为具有较好开发价值的创新药物，具有较好的应用价值和开发前景。同时也为龙牙楤木的临床应用及进一步开发提供了可靠的实验依据。本项目已发表SCI论文3篇，另有1 篇SCI 论文待发表；辅助培养毕业硕士研究生1名。