In cell analysis of Myosin Va function in organelle transport.

为了使我们身体的细胞正常运作，它们必须建立和维持一个复杂的专门内部结构（细胞器）的安排。这些细胞器的功能对生命至关重要，例如能量的产生。细胞器之间的运输和通讯对于细胞器、细胞和整个身体的正常功能都是至关重要的。与细胞器运输阻滞的重要性一致，这些过程中的其他缺陷导致许多常见的人类疾病，如囊性纤维化、高胆固醇血症、神经变性和某些形式的癌症。为了允许细胞器运输，细胞已经进化出一种复杂的（基于蛋白质的）机制，可以在不同的细胞器和细胞区域之间移动物质。为此需要的一类蛋白质是运动蛋白，它们将食物中的化学能转化为运动，并沿着亚细胞蛋白质轨道运输货物。被称为细胞骨架。其中一个马达，MyosinVa (MyoVa)，是这个提议的重点。MyoVa存在于许多细胞类型（人、动物、酵母和植物）中，并运输各种货物。其功能缺陷与危及生命的人类神经系统疾病和白化病（Griscelli综合征I型和Elejalde综合征）有关。因此，了解MyoVa的功能机制对了解人类神经系统和色素沉着系统的功能至关重要。在细胞外（体外）的人工实验环境中对MyoVa进行了广泛的研究，发现了许多特性，使MyoVa成为理想的货物转运体。然而，细胞环境比人工创造的环境要复杂得多，因此这些运动特性在细胞内运输（体内）中的重要性尚不清楚。在这项研究中，黑色素细胞（产生色素的皮肤细胞）中的黑色素小体运输将被用作模型系统，以确定MyoVa的哪些特性对活细胞中的货物运输至关重要。黑素体是大的，含有色素的细胞器，在显微镜下很容易看到。它们在细胞中心附近产生，并在需要MyoVa的过程中被运送到细胞周围。这个过程对皮肤色素沉着和防止太阳紫外线辐射至关重要。MyoVa的缺失导致转运缺陷，导致黑素小体聚集在细胞核附近。这种细胞缺陷导致皮肤和头发白化。用于解决细胞中MyoVa特性重要性的主要实验系统将是将特定运动特性被改变（突变）的MyoVa蛋白版本引入缺乏自身MyoVa的黑色素细胞。然后，将测试改变（或突变）的运动蛋白是否有能力通过恢复正常的黑素小体向细胞周围的运输来补偿天然蛋白的损失。本研究结果将为改善人类健康和开发新技术提供相关信息。

In order that the cells of our body function correctly they must establish and maintain a complex arrangement of specialised internal structures (organelles). The function of these organelles is essential for life e.g. energy production. Transport and communication between organelles is vital for both the normal function of organelles, cells and the whole body. In line with the importance of organelle transport blocks and other defects in these processes result in many common human diseases such as Cystic Fibrosis, hypercholesterolemia, neuro-degeneration and some forms of cancer. To allow organelle transport, cells have evolved a complex (protein-based) machinery that can move material between different organelles and areas of the cell. One class of proteins required for this are motor proteins that convert chemical energy, from food, into movement and transport cargo along subcellular protein ?tracks? known as the cytoskeleton. One of these motors, MyosinVa (MyoVa), is the focus of this proposal.MyoVa is present in many cell types (man, animals, yeasts and plants) and transports a variety of cargo. Defects in its function have been implicated in the life-threatening human neurological and albinism diseases (Griscelli syndrome Type I and Elejalde syndrome). Thus understanding the mechanism of MyoVa function is critical to understanding the function of the human nervous and pigmentation systems. MyoVa has been studied extensively in artificial experimental environments outside the cell (in vitro) that have led to the discovery of many properties that make MyoVa an ideal cargo transporter. However, the cellular environment is much more complex than artificially created environments, so the importance of these motor properties in intracellular transport (in vivo) remains unclear.In this study melanosome transport in melanocytes, pigment producing skin cells, will be used as a model system to determine which MyoVa properties are essential for cargo transport in living cells. Melanosomes are large, pigment containing organelles that are easily seen using a microscope. They are produced near the cell centre and are transported to the cell periphery in a process that requires MyoVa. This process is essential for skin pigmentation and protection from solar ultraviolet radiation. Loss of MyoVa causes defects in transport resulting in melanosomes clustering near the nucleus. This cellular defect results in skin and hair albinism.The main experimental system used to address the importance of MyoVa properties in cells will be to introduce versions of MyoVa protein in which specific motor properties have been altered (mutated) into melanocytes lacking their own MyoVa. The altered (or mutant) motor proteins will then be tested for their ability to compensate for the loss of the native protein by restoring normal melanosome transport into the cell periphery. The results of this study will provide information relevant to improvements in human health and development of novel technology.