EAPSI: Study of Mitochondrial Interactions at Presynaptic Terminals

线粒体是细胞内的重要机器，扮演着许多关键角色，从细胞的能量工厂到调节细胞程序性死亡的过程。能量产生的副产品是活性氧物种(ROS)，这是一种能够破坏细胞器并导致ROS进一步释放的分子。因此，细胞必须维持一个健康的、功能正常的线粒体群体。已确定的维持机制包括线粒体的循环和线粒体的持续分裂和连接。虽然这些机制已经在许多类型的细胞中得到了很好的研究，但在神经系统的一种细胞神经元中仍然知之甚少。神经元向中枢神经系统传递信号，需要大量能量，特别是在突触，这些位置远离细胞体，在那里也更需要移除受损的线粒体。这个项目将与莫纳什大学的线粒体分裂和融合专家迈克尔·瑞安教授合作，研究线粒体与细胞成分在代谢活动较高的位置的功能相互作用。神经元中线粒体质量控制机制的研究主要集中在它们在细胞体中的出现，而对于受损的线粒体如何从轴突和突触前终末移除的了解很少。除了分裂/融合事件和有丝分裂吞噬外，线粒体的选择性自噬、线粒体沿微管的运输可能会用细胞体中的健康细胞器取代受损的细胞器。为了研究这些机制中的哪些是在氧化应激反应中被激活的，我们将把一种针对线粒体的可光激活的产生ROS的多肽引入到我们感兴趣的蛋白质已经被荧光染料标记的活细胞中。使用共聚焦实时成像和超分辨率显微镜，将产生暴露在绿光下或未暴露在绿光下的突触前线粒体的快照，并进行比较，以评估哪些因素参与了受损线粒体的移除。该奖项由东亚和太平洋夏季研究所计划设立，支持一名美国研究生的夏季研究，由NSF和澳大利亚科学院联合资助。

Mitochondria are important machines inside cells which play a number of key roles, from being the energy factories of the cell to regulating the process of programmed cell death. A byproduct of energy production is reactive oxygen species (ROS), molecules capable of damaging organelles and leading to further release of ROS. Therefore, cells must maintain a population of healthy, functioning mitochondria. The maintenance mechanisms that have been identified include the recycling of mitochondria and the ongoing division and joining together of mitochondria. While these mechanisms have been well studied in numerous types of cells, they remain poorly understood in neurons, a type of cell of the nervous system. Neurons transmit signals to and from the central nervous system, requiring high amounts of energy, especially at synapses, sites distant from the cell body where there would also be a greater need to remove damaged mitochondria. In collaboration with Professor Michael Ryan at Monash University, an expert in mitochondrial fission and fusion, this project will investigate functional interactions of mitochondria with cellular components in locations of the cell with high metabolic activity.The study of mitochondrial quality control mechanisms in neurons has focused on their occurrence in the cell body, while little is known about how damaged mitochondria are removed from axons and presynaptic terminals. In addition to fission/fusion events and mitophagy, the selective autophagy of mitochondria, trafficking of mitochondria along microtubules may act to replace damaged organelles with healthy ones from the cell body. To study which of these mechanisms are activated in response to oxidative stress, a photoactivatable ROS-producing peptide targeted to mitochondria will be introduced into live cells in which our proteins of interest have been labeled with fluorescent dyes. Using confocal live imaging and super-resolution microscopy, snapshots of presynaptic mitochondria exposed to or unexposed to green light will be generated and compared to assess which factors are involved in the removal of damaged mitochondria.This award, under the East Asia and Pacific Summer Institutes program, supports summer research by a U.S. graduate student and is jointly funded by NSF and the Australian Academy of Science.