How does the Scar/WAVE complex control actin protrusions and cell migration? A combined cell biology and cryo-EM approach.

我们试图通过爬行来理解细胞迁移，这一过程在整个生长、生命和死亡过程中都很重要。在生命的早期，胚胎的形状和结构依赖于迁移，随着神经元的末端相互爬行，新的神经连接形成。正常生命是由细胞迁移维持的--组织的生长和正常损伤的修复需要细胞以精确控制的方式移动。免疫反应需要细胞通过组织迁移到淋巴组织等结构中，以满足和交换信息。疾病过程通常使用细胞迁移。也许最广为人知的案例是癌症转移。癌细胞可能会开始从原来的肿瘤中迁移出去。在这样做的过程中，它们进入血液或淋巴管，并扩散到其他部位，支撑了癌症造成的大部分损害。细胞使用类似的结构爬行，称为板脂和伪足。这些突起从细胞的前部突起，与当地环境接触并附着，然后为细胞提供框架，以拉动和驱动自己向前。它们由一种名为肌动蛋白的小蛋白质组成，它们的形成和维持由一种名为疤痕/波浪复合体或WRC的大型蛋白质组件控制。在这笔赠款中，我们试图了解世界资源中心是如何运作的。如果我们能够理解这一点，我们就可以理解细胞如何选择是否移动，以及当他们这样做时他们向哪个方向移动。我们想了解细胞通过什么机制将不活跃的WRC转化为活跃的形式。非活性形式存在于细胞质中，很少与其他蛋白质相互作用。活性形式的行为完全不同-它似乎通过结合、定位和激活许多制造板脂和伪足的蛋白质来发挥枢纽的作用。在这笔赠款中，我们寻求以下问题的答案：1.活跃的WRC最重要的属性是什么？有没有一种特别重要的蛋白质？如果有，是什么蛋白质？如果不是，它只是一个普通的枢纽，将细胞移动所需的许多蛋白质聚集在一起？2.如果我们用先进的冷冻电子显微镜技术揭示WRC的分子结构，我们能理解这种从非活性形式到活性形式的变化是如何安排的吗？我们的初步数据显示，目前关于这一原理的想法可能是错误的。给出了WRC的结构--我们能确定细胞中发生了什么来控制WRC的激活吗？和4.我们能找出活跃的WRC信号是如何关闭的吗？对这四个问题的完整回答将使我们彻底重新关注如何理解细胞迁移，并告知每一位研究移动细胞的生物医学科学家。

We seek to understand cell migration by crawling, a process which is important throughout growth, life and death.Early in life, embryos depend on migration for their shape and structure, and new nerve connections form as the ends of neurons crawl towards one another. Normal life is maintained by cell migration - growth of tissues and repair of normal damage require cells to move in precisely-controlled ways. Immune responses require cells that migrate through tissues and into structures like lymph oneds to meet and exchange information. And disease processes often use cell migration. Perhaps the best-known case is cancer metastasis. Cancer cells may start to migrate away from their original tumour. In doing so they enter the bloodstream or lymph vessels, and spread to other sites, underpinning much of the damage caused by cancer.Cells crawl using similar structures called lamellipods and pseudopods. These protrude from the front of the cell, engage with the local environment and adhere, then provide the framework for cells to pull on and drive themselves forwards. They are made of a small protein called actin, and their formation and maintenance are controlled by a large protein assembly called the Scar/WAVE complex, or WRC. In this grant we seek to understand how the WRC works. If we can understand this, we can understand how cells choose whether to move, and which direction they go in when they do so.We want to understand the mechanisms through which cells convert the inactive WRC to the active form. The inactive form resides in the cytoplasm and interacts with few other proteins. The active form behaves completely differently - it seems to act as a hub by binding, localising and activating many the proteins that make lamellipods and pseudopods. In this grant we seek answers to the following questions:1. What is the most important property of active WRC? Is there one protein that is particularly crucial, and if so what is it? And if not, does it just act as a general hub, pulling together many of the proteins a cell needs to move?2. If we reveal the molecular structure of the WRC, using the advanced technique of cryo-electron microscopy, can we understand how this change from inactive to active forms is orchestrated? Our preliminary data show that current ideas for how this works are probably wrong.3. Given a structure for WRC - can we identify what happens in the cell to control the activation of the WRC? And4. Can we find out how the active WRC signal is turned off?A full answer to these four questions would cause a complete refocus in how we understand cell migration, and inform every biomedical scientist who works on cells that move.