The mechanochemical control of T-cell directional migration under flow

流动条件下T细胞定向迁移的机械化学控制 丹尼尔Hammer（PI）和Janis K. Burkhardt（合作研究者） 项目摘要 T淋巴细胞是适应性免疫反应的关键参与者，运动性对其功能至关重要。T- 细胞配备有多种不同的粘附分子， 在整个免疫系统中的差异。此外，T细胞通常必须在施加的流场下起作用 因为它们通过脉管系统和心脏系统运输。我们的目标是了解T细胞如何对 它们遇到的不同粘附配体和剪切速率有效地迁移到炎症部位， 免疫通讯在分子水平上理解这一过程对于开发 治疗炎症和感染性疾病以及癌症的治疗策略 最近，我们发现定向T细胞迁移作为配体类型的函数而变化， 它们所接触的剪切速率。当放置在一个有血管细胞的表面时 粘附分子-1（VCAM-1），它与α 1-整联蛋白受体VLA-4结合，T细胞向下游爬行 在流动方向上（在流动方向上）。然而，当放置在细胞间粘附的表面上时， 分子-1（ICAM-1）与β 2受体LFA-1结合，T细胞逆着流动方向爬行，就像一个 鲑鱼逆流而上上游迁移的幅度取决于剪切速率，其中T细胞更多 随着剪切速率的增加致力于向上游迁移。在表面上，粘附分子 混合，任何量的ICAM-1支持上游迁移。当流动被移除时，T细胞表现出 迁移记忆，但只有当他们已经暴露于ICAM-1和VCAM-1。这一观察指出， 涉及两种不同整联蛋白受体之间的串扰的新机制。 我们建议研究在流动条件下驱动T细胞向上游迁移的机制， ICAM-1与迁移记忆的起源我们假设，上游迁移是由E2引起的， 整合素形成捕获键，其将细胞保持在适当位置，而整合素连接产生的信号 加强粘附相互作用，刺激前沿肌动蛋白的聚合， 迁移为了测试这一点，我们将使用分子工程，流动室，微图案表面， 微制造柱阵列检测器（mPAD）以测量由迁移细胞施加的力。我们有 初步证据表明，其他运动的阿米巴样细胞，如永生化的KG 1a细胞系， 同样的现象，有利于我们使用分子工程工具和成像方法来识别 相关分子通过剖析这一迷人现象背后的机制，我们希望 阐明整合素依赖性T细胞运输的关键特征。我们在这项工作中的目标是：1。测量 T细胞和KG 1a定向运动和迁移记忆的动力学; 2.识别信号和离合器 负责响应于α 1和α 2整联蛋白配体的流动下的差异迁移的分子;和3. 测量当T细胞在整联蛋白配体上定向扩散和爬行时力产生的机制。

The mechanochemical control of T-cell directional migration under flow Daniel A. Hammer (PI) and Janis K. Burkhardt (co-Investigator) Project Summary T-lymphocytes are key players in the adaptive immune response, and motility is critical to their function. T- cells are equipped with multiple different adhesion molecules that interact with ligands that are expressed differentially throughout the immune system. Furthermore, T-cells often must act under an imposed flow field as they traffic through the vasculature and lymphic system. Our goal is to understand how T-cells respond to the different adhesion ligands and shear rates they encounter to effectively migrate to sites of inflammation and immune communication. Understanding this process at the molecular level is important for development of therapeutic strategies to treat inflammatory and infectious diseases, and cancer Recently, we have discovered that directional T-cell migration varies as a function of the type of ligand they encounter and the shear rate to which they are exposed. When placed on a surface bearing vascular cell adhesion molecule-1 (VCAM-1), which engages the 1-integrin receptor VLA-4, T-cells crawl downstream under flow (in the direction of flow). However, when placed on a surface bearing intercellular adhesion molecule-1 (ICAM-1), which engages the 2-receptor LFA-1, T-cells crawl against the direction of flow, like a salmon swims upstream. The magnitude of upstream migration depends on shear rate, with T-cells more committed to upstream migration as the shear rate increases. On surfaces in which adhesion molecules are mixed, any amount of ICAM-1 supports upstream migration. When the flow is removed, T-cells exhibit migrational memory, but only if they have been exposed to both ICAM-1 and VCAM-1. This observation points to a novel mechanism of crosstalk between two distinct integrin receptors. We propose to investigate the mechanisms that drive the upstream migration of T-cells under flow on ICAM-1, and the origins of migrational memory. We hypothesize that upstream migration is caused by 2 integrin forming a catch bond, which holds the cell in place while signals generated by integrin ligation strengthen adhesive interactions and spur the polymerization of actin at the leading edge, driving forward migration. To test this, we will use molecular engineering, flow chambers, micropatterned surfaces, and microfabricated post array detectors (mPADs) to measure forces exerted by the migrating cell. We have preliminary evidence that other motile amoeboid cells such as the immortalized KG1a cell line display the same phenomenon, facilitating our use of molecular engineering tools and imaging methods to identify the relevant molecules. By dissecting the mechanisms that underlie this fascinating phenomenon, we expect to elucidate key features of integrin-dependent T cell trafficking. Our aims in this work are to: 1. Measure the dynamics of T-cell and KG1a directional motion and migrational memory; 2. Identify the signals and clutch molecules responsible for the differential migration under flow in response to 1 and 2 integrin ligands; and 3. Measure the mechanisms of force generation when T-cells spread and crawl directionally on integrin ligands.