Multi-cue Guidance of Mesenchymal Cell Migration

摘要 在各种环境中的细胞在一个称为趋化性的过程中向可溶的化学信号迁移。 尽管经过了近一个世纪的研究，但趋化性的机制基础仍然不完全。 明白了。血小板衍生生长因子(PDGF)和其他化学诱导剂的空间梯度 间充质细胞在组织中的运动，以协调和加速生理上的重要作用 伤口愈合和间充质趋化等过程与病理过程有关。 心血管疾病和纤维化疾病等疾病。尽管成纤维细胞和其他 间充质细胞在伤口愈合和其他疾病过程中发挥作用，如转移性癌症和 纤维化：对间充质细胞定向迁移机制的严格理解 是最近才出现的。为了进一步推进，需要一种量化的、综合的方法。 具体地说，有必要阐明中央调控途径是如何与其他途径联网的，以及如何 它们在影响细胞行为的亚细胞位置和时间方面是协调的。在…的背景下 定向间充质细胞迁移，另一层复杂性是梯度条件的变化 (中点浓度/面密度和陡度)。在新的技术进步的推动下，我们 准备解决这些与趋化和触觉趋化及其组合有关的新问题 在多线索设置中的影响。我们的具体目标如下： 目的1：破译形成间充质趋化的多个信号轴的动力学。 我们将测试这一假设，即突起动力学由Arp2/3的亚稳态推拉控制 复杂的和NMII活性，这是不够偏向趋化梯度。具有稳定的 在最高梯度突起中，活性PKC的极化，NMII的失活为 为支持Arp2/3的信号提供“风暴中的端口”，以调节更具生产力的突起。 目的2：探讨触觉感觉和信号放大的动力学。我们假设 ECM梯度上的差异整合素参与通过反馈推动显著的细胞迁移偏向 原Arp2/3信号轴的扩增。如果是这样的话，这将意味着触角梯度能够 偏爱间充质细胞中的前Arp2/3信号，达到趋化梯度所不能达到的程度。 目标3：定义多线索情景中的梯度协同作用和优先顺序。尽管存在关联性 对于体内间充质细胞的引导，细胞如何对共提呈做出反应是完全未知的。 在受控设置中的两种渐变类型中。考虑趋化作用和触觉趋化作用的影响 成纤维细胞中肌动蛋白细胞骨架的动态调节，我们假设两个梯度 如果以平行的方向呈现，就会产生协同效应。通过以反平行或反平行的方式呈现梯度 正交方向，我们将确定单元如何对这两种类型的提示进行优先排序。

SUMMARY Cells in a variety of contexts migrate towards soluble chemical cues in a process known as chemotaxis. Despite nearly a century of study, the mechanistic underpinnings of chemotaxis remain incompletely understood. Spatial gradients of platelet-derived growth factor (PDGF) and other chemoattractants direct the movements of mesenchymal cells in tissues to coordinate and accelerate physiologically important processes such as wound healing, and mesenchymal chemotaxis has been implicated in pathological conditions such as cardiovascular and fibrotic diseases. Despite the central role that fibroblasts and other mesenchymal cells play in wound healing and other disease processes such as metastatic cancer and fibrosis, a rigorous understanding of mechanisms governing the directed migration of mesenchymal cells is only recently emerging. To advance further, a quantitative, integrative approach is required. Specifically, it is necessary to elucidate how the central regulatory pathways network with others and how they are coordinated with respect to subcellular location and time to affect cell behavior. In the context of directed mesenchymal cell migration, another layer of complexity is the variation of gradient conditions (midpoint concentration/surface density and steepness). Enabled by new engineering advances, we are poised to tackle these new questions related to chemotaxis and haptotaxis and to their combinatorial influence in multi-cue settings. Our Specific Aims are as follows: Aim 1: Decoding the dynamics of multiple signaling axes that shape mesenchymal chemotaxis. We will test the hypothesis that protrusion dynamics are governed by the metastable push/pull of Arp2/3 complex and NMII activities, which are insufficiently biased by a chemotactic gradient. With stable polarization of active PKC in the most-up-gradient protrusion, the inactivation of NMII there provides a ‘port in the storm’ for pro-Arp2/3 signaling to mediate more productive protrusion. Aim 2: Probing the dynamics of haptotactic sensing and signal amplification. We hypothesize that differential integrin engagement on ECM gradients drives significant cell migration bias through feedback amplification of the pro-Arp2/3 signaling axis. If so, it would imply that haptotactic gradients are able to bias pro-Arp2/3 signaling in mesenchymal cells to an extent that chemotactic gradients cannot. Aim 3: Defining gradient synergy and prioritization in multi-cue scenarios. Despite the relevance for guidance of mesenchymal cells in vivo, it is completely unknown how cells respond to co-presentation of the two gradient types in a controlled setting. Considering how chemotaxis and haptotaxis affect dynamic regulation of the actin cytoskeleton in fibroblasts, we hypothesize that the two gradients synergize when presented in a parallel orientation. By presenting the gradients in an antiparallel or orthogonal orientation, we will determine how cells prioritize the two types of cues.