Regulation of cell migration by biochemical and mechanical environmental cues

细胞迁移是一种基本现象，对单细胞和多细胞生物体的生命至关重要。简单的生物，如阿米巴，必须迁徙以寻找食物和交配。脊椎动物等多细胞生物的复杂性带来了个体细胞和细胞组在发育形态形成过程中定位的必要性，这在很大程度上是通过细胞的定向迁移实现的。在成人中，定向迁移在广泛的生理和病理过程中发挥着重要作用，包括皮肤和肠道上皮的更新、免疫系统功能、伤口愈合以及癌症转移和心血管疾病。在过去的二十年里，在理解调控定向细胞迁移的复杂机制方面取得了巨大的进展。这包括发现指导细胞迁移的各种细胞外线索，如生化梯度、机械力以及细胞外基质(ECM)硬度和拓扑的梯度。另一个关键发现是确定了将单个环境线索转化为定向细胞运动的信号通路。尽管如此，在同时呈现多个不同性质的线索的组织环境中，调控定向细胞运动的分子机制知之甚少。*在这里，我们建议结合最先进的生物物理技术来揭示这些机制：具有可调机械性能的合成水凝胶来模拟生物组织的僵硬景观，以及微流控技术来控制可溶生化线索的局部浓度。通过将这些方法与定量活细胞成像和细胞内信号通路的分子分析相结合，我们将揭示整合多种线索的特定分子角色，并在组织环境中指导细胞迁移。*本建议的具体目标包括：(1)在一种新的定向细胞迁移的体外模型中确定化学和机械引导线索之间的串扰；(2)确定在多种线索共存的环境中调节化学和机械引导线索之间串扰的分子机制。这项工作将阐明生化信号如何调节由物理梯度(ECM硬度)引导的细胞迁移。它还将确定整合生化和机械指导信号的信号通路，并动态调节细胞骨架网络，以在关键的生理或病理过程中提供刻板印象的细胞行为，包括肿瘤转移。

Cell migration is a fundamental phenomenon that is critical for life of unicellular and multicellular organisms. Simple organisms, such as amebae, have to migrate to find food and to mate. Complexity of multicellular organisms, such as vertebrates, brings the necessity for individual cells and groups of cells to position themselves during developmental morphogenesis that is largely achieved through directed cell migration. In the adult, directed migration plays an important role in a wide range of physiological and pathological processes, including renewal of skin and intestinal epithelium, immune system function, and wound healing, as well as cancer metastasis and cardiovascular diseases.***Over the last two decades, immense progress has been made in understanding the complexity of mechanisms that regulate directed cell migration. This includes discovery of various extracellular cues such as biochemical gradients, mechanical forces, and gradients of extracellular matrix (ECM) stiffness and topology that guide migrating cells. Another key finding was identification of signaling pathways transducing individual environmental cues into directed cell movement. Despite this, much less is known about molecular mechanisms regulating directional cell movement in a tissue environment where multiple cues of different nature are presented simultaneously.***Here, we propose to reveal these mechanisms by using a combination of state-of-the-art biophysical techniques: synthetic hydrogels with tunable mechanical properties to mimic stiffness landscape of biological tissues and microfluidics to control local concentration of soluble biochemical cues. By coupling these approaches with quantitative live-cell imaging, and molecular analysis of intracellular signaling pathways we will reveal specific molecular players that integrate multiple cues, and direct cell migration in tissue environment.***The specific aims of this proposal include: (1) To determine the crosstalk between chemical and mechanical guidance cues in a novel in vitro model of directed cell migration; (2) To determine the molecular mechanisms mediating the crosstalk between chemical and mechanical guidance cues and directing cells in environments where multiple cues co-exist. This work will shed light on how biochemical cues regulate cell migration guided by physical gradients (ECM stiffness). It will also identify signaling pathways that integrate biochemical and mechanical guidance cues and dynamically regulate the cytoskeletal network to provide stereotypical cell behavior during crucial physiological or pathological processes, including tumor metastasis.**