Integrin Recycling and Adhesion Formation in Cell Migration

总结 整合素是几乎所有细胞用于迁移的主要细胞粘附分子。在粘附过程中，整合素 聚集形成多种复合体，包括新生粘连、小病灶复合体和成熟病灶粘连。 通过这些部位，细胞对基质施加张力。我们所知道的关于附着力的组装 复合物来自于对细胞分离和重新接种在细胞外基质（ECM）配体上的研究。这种细胞扩散 该试验对于理解粘连形成机制是有效的，但它不能完全概括关键特征 以及细胞迁移过程中的粘附形成行为。特别是，它不能解释极化的形成， 在细胞前部附近的粘附，并且没有考虑整合素的内吞再循环，这是至关重要的 用于2D和3D环境中的细胞迁移。我们已经开发了一种新的粘着斑组装测定法， 严重依赖于来源于粘连中整合素内吞作用的再循环整合素。有趣的是， 以无配体和活性构象行进，并导致在引导区高度极化的粘连形成。 迁移细胞的边缘。我们将使用细胞生物学，生物化学和高分辨率成像方法来测试 假设再循环的整合素在靠近前缘的胞吐位点附近播种新的粘附形成。 我们的三个目标是：1）检查整合素循环，激活状态，胞吐位点和粘附之间的关系 形成，2）确定微管细胞骨架如何有助于粘附的极化形成， 再循环的整合素，以及3）确定细胞外基质拓扑结构和刚度如何影响粘附形成， 回收整合素。在整个过程中，我们将研究如何形成粘连从回收整合素影响的能力， 细胞迁移。这项工作将促进对细胞用于粘附的基本机制的理解， 细胞迁移，这可能导致在细胞迁移不受调节的情况下进行干预的新策略，例如 癌症转移和持续性炎症。

Summary Integrins are the major cell adhesion molecules used by virtually all cells to migrate. During adhesion, integrins are clustered to form a variety of complexes including nascent adhesions, small focal complexes and mature focal adhesions. Through these sites, the cell exerts tension on the substratum. Much of what we know about the assembly of adhesion complexes comes from studies on cells detached and replated on extracellular matrix (ECM) ligands. This cell spreading assay has been powerful for understand mechanisms of adhesion formation, yet it does not fully recapitulate key features and behaviors of adhesion formation during cell migration. In particular, it does not account for the polarized formation of adhesions near the front of the cell and does not take into account the endocytic recycling of integrins, which is critical for cell migration in both 2D and 3D environments. We have developed a new focal adhesion assembly assay that is critically dependent on recycled integrin derived from the endocytosis of integrins in adhesions. Interestingly, this integrin travels in an unliganded and active conformation and leads to the highly polarized formation of adhesions at the leading edge of migrating cells. We will use cell biological, biochemical and high resolution imaging approaches to test the hypothesis that recycled integrin acts to seed new adhesion formation near sites of its exocytosis near the leading edge. Our three aims are: 1) to examine the relationship between integrin recycling, activation state, exocytic sites and adhesion formation, 2) to determine how the microtubule cytoskeleton contributes to the polarized formation of adhesions from recycled integrins and, 3) to determine how extracellular matrix topology and stiffness affect adhesion formation from recycled integrins. Throughout, we will examine how the formation of adhesions from recycled integrins affect the ability of cells to migrate. This work will advance understanding of the basic mechanisms cells use to polarize their adhesions for cell migration, which may lead to new strategies for intervention in cases where cell migration is unregulated, such as cancer metastasis and persistent inflammation.