Adhesion and Cytoskeleton Dynamics in Cell Migration

描述(由申请人提供)：适当调节细胞迁移对人类健康至关重要。损害细胞活力的基因缺陷会导致出生缺陷，如大脑畸形和免疫缺陷。另一方面，迁移和侵袭的能力将可治愈的肿瘤转化为不可治愈的转移性疾病。此外，为了实现再生医学的一个主要目标，即创造人造器官和组织，不仅需要指定所有合适的细胞类型，而且还需要控制它们的组织、交流和运动。因此，了解和掌握控制组织形态发生，特别是细胞迁移的机制是非常重要的。这些都是我们研究的长期目标。几十年的研究揭示了控制组织培养皿中单个细胞运动的分子和机制。细胞如何在错综复杂的自然环境中移动还不太清楚。在体内，细胞通常以相互连接的片状、管状、链状和簇状移动。尽管它们无处不在，也很重要，但这种集体细胞的行为并没有像单个细胞那样得到充分的研究。在复杂环境中移动的细胞的形状可能与在玻璃上无阻碍地迁移的细胞的形态有很大的不同。这些观察结果提出了许多问题。例如，集体细胞运动的机制与单个细胞运动有何相似或不同之处，以及细胞形状的巨大多样性是如何实现的？单个和集体细胞迁移之间的一个主要区别是，细胞集体移动时，即使它们移动也能保持细胞与细胞之间的粘附性。虽然我们现在知道了许多对细胞运动很重要的分子，但我们对这些蛋白质的活动在空间和时间上是如何协调的知之甚少。为了解决这些问题，我们开发了一个相对简单和遗传上容易处理的模型来研究集体细胞迁移：果蝇卵巢中的边缘细胞。我们建议使用我们开发的新方法来测量甚至操纵体内的蛋白质活性和机械力。我们的具体目标是：1)验证细胞-细胞黏附在集体迁移细胞中发挥多种关键功能的假设，包括集群组织、方向感知和突起的稳定。我们还将直接比较体内单个细胞和集体细胞迁移的机制。2)测试RAC和酪氨酸激酶之间的反馈协调集体迁移过程中的极性、突起和粘连的假设。在这里，我们还建议确定酪氨酸激酶的功能底物。3)测试“原肌球蛋白(TM)编码假说”，该假说认为细胞形状和行为的多样性可以归因于动态F-肌动蛋白结构的多样性，而F-肌动蛋白结构的多样性又取决于细胞中存在的TM亚型的组合。

DESCRIPTION (provided by applicant): Properly regulated cell migrations are essential to human health. Genetic defects that impair cell motility cause birth defects such as brain malformations and immune deficiencies. On the other hand, the ability to migrate and invade converts curable tumors into incurable, metastatic disease. In addition, in order to achieve a major goal of regenerative medicine, which is the creation of artificial organs and tissues, it is necessary not only to specify all of the appropriate cell types, but also to control their organization, communication, and movements. Therefore it is of great importance that we understand and harness the mechanisms controlling tissue morphogenesis in general, and cell migration in particular. These are the long-term goals of our studies. Decades of research have revealed the molecules and mechanisms that control the movements of single cells in tissue culture dishes. How cells move through their intricate natural environments is less well-understood. In vivo cells often move in interconnected sheets, tubes, strands, and clusters. Despite their ubiquity and importance, such collective cell behaviors are not as well-studied as those of single cells. The shapes of cells moving through complex environments can differ greatly from the morphology of a cell migrating, unobstructed, on glass. These observations raise numerous questions. For example, how do the mechanisms of collective cell movement resemble or differ from single cell motility, and how is the great diversity of cell shapes achieved? One major difference between single and collective cell migration is that cells moving collectively maintain cell-cell adhesion even as they move. While we now know many of the molecules that are important for cell movements, we know far less about how the activities of these proteins are coordinated in space and time. To address these questions we have developed a relatively simple and genetically tractable model for the study of collective cell migration: the border cells in the Drosophila ovary. We propose to use new methods that we have developed to measure and even manipulate protein activities and mechanical forces in vivo with light. Our specific aims are to: 1) test the hypothesis that cell-cell adhesion serves multiple, critical functions in collectively migrating cells, including cluster organization, direcion sensing, and stabilization of protrusions. We will also compare directly the mechanisms of single and collective cell migration in vivo. 2) test the hypothesis that feedback between Rac and a tyrosine kinase coordinates polarity, protrusion, and adhesion during collective migration. Here we also propose to identify functional substrates of the tyrosine kinase. 3) test the "Tropomyosin (Tm) code hypothesis," which postulates that the diversity of cell shapes and behaviors can be attributed to the diversity of dynamic F-actin structures, which in turn depend upon the combination of Tm isoforms present in a cell.