Milton and the Transport of Mitochondria

描述(由申请人提供)：马达蛋白在细胞质内移动细胞器，从而有助于这些细胞器的适当分布。从细胞生物学的观点来看，涉及的马达，包括动蛋白家族的成员，是相当感兴趣的：马达如何与它们适当的货物耦合？它们如何将这些货物引导到特定的位置？它们的活动如何受到调节？细胞器的适当分布如何实现和维持？细胞器的适当分布可能会给细胞带来复杂的问题。这一过程中的缺陷可导致周围神经病变，并与一些神经退行性疾病有关。线粒体是高度可移动的细胞器。它们必须将自己分布在细胞内，以便能够向细胞的每个部分提供足够的能量，以满足该部分的需求。线粒体在神经元轴突和树突上、下的运动是线粒体运输最引人注目的例子之一。在一种名为米尔顿的果蝇突变体中，神经轴突和终末中完全没有线粒体。米尔顿基因编码的蛋白质在线粒体上发现，并与运动蛋白Kinesin有关。目前的提议试图了解弥尔顿在神经元和其他细胞内线粒体运输中的作用。第一个目标，主要涉及荧光和视频显微镜，试图确定什么形式的运输需要弥尔顿，并确定米尔顿是在所有线粒体上，还是只在那些正在运输的线粒体上。随后的目的主要是通过生物化学研究来探索弥尔顿作用的机制。他们询问弥尔顿如何定位于线粒体，弥尔顿如何与动蛋白相互作用，以及米尔顿是否充当连接动蛋白与线粒体的适配器。在这个过程中，该提案还研究了米尔顿基因的选择性剪接，以及米尔顿翻译后修饰的潜在调节作用。

DESCRIPTION (provided by applicant): Motor proteins move organelles within the cytoplasm of cells and thereby contribute to the appropriate distribution of those organelles. The motors involved, including members of the kinesin family, are of considerable interest from the cell biological point of view: how do motors couple to their appropriate cargos?; how do they direct those cargos to particular locations?; how is their activity regulated?; how is the proper distribution of the organelle achieved and maintained? The proper distribution of an organelle can pose a complex problem for a cell. Defects in this process can cause peripheral neuropathies and have been implicated in some neurodegenerative diseases. Mitochondria are highly mobile organelles. They must distribute themselves within cells so as to be able to supply sufficient energy to each part of a cell to match the needs of that part. The movement of mitochondria up and down axons and dendrites of neurons is one of the most dramatic examples of mitochondrial transport. In a Drosophila mutant called milton, mitochondria are completely absent from nerve axons and terminals. The protein encoded by the milton gene is found on mitochondria and is associated with the motor protein kinesin. The present proposal seeks to understand the role of Milton in the transport of mitchondria within neurons and other cells. The first aim, involving primarily fluorescent and video microscopy, seeks to determine what forms of transport require Milton and to determine if Milton is on all mitochondria or only those that are undergoing transport. The subsequent aims probe the mechanism of Milton action, primarily through biochemical studies. They inquire how Milton is localized to mitochondria, how Milton interacts with kinesin, and whether Milton serves as an adaptor that links kinesin to the mitochondrion. In the process, the proposal also examines the alternative splicing of the Milton gene and the potential regulatory role of post-translational modifications of Milton.