In vivo regulation of bi-directional transport

近年来的生物物理学研究在阐明单分子的功能方面取得了很大进展 电动机在体外然而，体内分子功能远比这些体外研究复杂 预测：与体外观察到的单向运动相反，许多囊泡或其他货物双向运动。 方向性地沿着微管，经常反转它们的行进方向。然而，运输可能 监管，使货物移动平均到正确的地方。为了了解这种运输是如何 监管需要开发能够量化的新工具体内个体运动 具有高时空分辨率的货物。这项研究开发了这种生物物理工具， 将它们与遗传学和生物化学相结合，以研究运动或运动复合体的功能， vivo. 具体而言，双向运动的脂滴在早期果蝇胚胎进行了研究。工作 在概念上可以分为两种互补的方法。第一，生物物理特性 突变的影响，使用光学镊子和粒子跟踪和分析，以确定具体的 蛋白质在运输途径中的物理作用。一个目标是测试一个理论框架， 一个具有特定功能的复合物的存在，并将每个蛋白质置于这个框架内。第二 一种方法采用生物化学技术来鉴定参与调控的其他蛋白质， 运输，并确定不同蛋白质之间的相关相互作用。这些信息将在 分子水平上生物物理决定的功能是如何产生的，并将直接研究 复杂的假设在生物化学方法中鉴定的蛋白质的功能将直接 使用生物物理分析进行研究。 双向运输与公共卫生直接相关：疱疹等病毒通过细胞传播 以双向方式;许多重要的货物如线粒体和内体双向移动。 此外，在这里研究的一些基因突变，如Lis1，导致人类出生缺陷。最后， 更好地了解转运可能有助于设计新的药物输送系统。

Recent biophysical studies have made great progress in clarifying the function of single molecular motors in vitro. However, in vivo molecular function is far more complicated than these in vitro studies predict: contrary to the uni-directional motion observed in vitro, many vesicles or other cargos move bi- directionally along microtubules, frequently reversing their direction of travel. Nonetheless, transport can be regulated, so that the cargo moveson averagetothe right place. To understand how such transport is regulated requires the development of new tools capable of quantifyingin vivothe motion of individual cargos with high temporal and spatial resolution. The research develops such biophysical tools, and combines them with genetics and biochemistry to investigate the function of motors or motor complexes in vivo. Specifically, bi-directional motion of lipid droplets in early Drosophila embryos is investigated. The work can be conceptually divided into two complimentary approaches. The first, the biophysical characterization of the effects of mutations, uses optical tweezers and particle tracking and analysis to determine the specific physical role of proteins in the transport pathway. One goal is to test a theoretical framework hypothesizing the existence of a complex with certain functions, and place each protein within this framework. The second approach employs biochemical techniques to identify additional proteins involved in the regulation of transport, and determine relevant interactions between the different proteins. This information will clarify at the molecular level how the biophysically determined functions come about, and will directly investigate the hypothesized complex. The function of the proteins identified in the biochemical approaches will be directly investigated using the biophysical assays. Bi-directional transport is directly related to public health: viruses such as herpes spread through cells in a bi-directional manner; many important cargos like mitochondria and endosomes move bi-directionally. Further, mutation in some of the genes investigated here, such as Lis1, lead to human birth defects. Finally, a better understanding of transport might allow the design of new drug delivery systems.