Devireddy Swathi, Sung Hyun, Liao Pin-Chao, Garland-Kuntz Elisabeth, Hollenbeck Peter J
Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA.
Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA.
Methods Enzymol. 2014;547:131-50. doi: 10.1016/B978-0-12-801415-8.00008-4.
The extreme geometry of neurons spreads the need for mitochondrial functions out irregularly across vast cellular distances. This makes the long-distance transport of mitochondria a critical feature of their function in neurons. Axonal transport of mitochondria has been studied profitably in a variety of in vitro systems, particularly embryonic neurons grown in culture. This has allowed not only detailed motility analysis via light microscopy but also the ability to challenge the system with pharmacological agents and transfection. It does, however, carry caveats about its relevance to events in cells of the intact nervous system. In recent years, it has become possible to observe, quantify, and analyze the behavior of mitochondria within axons of the nervous system of live organisms. Here, we describe how to prepare the Drosophila larva for direct observation of mitochondrial axonal transport and how to gather and analyze motility data from this preparation, using confocal microscopy. This system takes advantage of our ability in Drosophila to express mitochondrially targeted fluorescent proteins in specific neuronal cell types, which allows us to visualize their traffic with ease, and to distinguish anterograde from retrograde traffic. Drosophila genetics also allows the analysis of mutations, gene overexpression, and knockdowns that affect mitochondrial function, including models of neurodegenerative disease. In addition, this preparation allows the visualization of the distribution and morphology of mitochondria in cell bodies within the central nervous system and in synapses. It is also possible to analyze mitochondrial functions other than transport, such as inner membrane potential, using this preparation.
神经元的极端几何形状使得线粒体功能的需求在巨大的细胞距离上不规则地分散开来。这使得线粒体的长距离运输成为其在神经元中功能的一个关键特征。线粒体的轴突运输已经在各种体外系统中得到了有益的研究,特别是在培养中生长的胚胎神经元。这不仅允许通过光学显微镜进行详细的运动分析,还能够用药理学试剂和转染来挑战该系统。然而,它对于完整神经系统细胞中事件的相关性存在一些警告。近年来,观察、量化和分析活生物体神经系统轴突内线粒体的行为已经成为可能。在这里,我们描述了如何制备果蝇幼虫以直接观察线粒体轴突运输,以及如何使用共聚焦显微镜从该制备物中收集和分析运动数据。这个系统利用了我们在果蝇中能够在特定神经元细胞类型中表达线粒体靶向荧光蛋白的能力,这使我们能够轻松地可视化它们的运输,并区分顺行运输和逆行运输。果蝇遗传学还允许分析影响线粒体功能的突变、基因过表达和基因敲低,包括神经退行性疾病模型。此外,这种制备物还允许可视化中枢神经系统内细胞体和突触中线粒体的分布和形态。使用这种制备物还可以分析除运输之外的线粒体功能,例如内膜电位。