Regulation of cell migration by biochemical and mechanical environmental cues

细胞迁移是单细胞和多细胞生物生命的一种基本现象。简单的生物，如变形虫，必须迁徙寻找食物和交配。复杂的多细胞生物，如脊椎动物，需要单个细胞和细胞群在发育形态发生过程中定位自己，这主要是通过定向细胞迁移来实现的。在成人中，定向迁移在广泛的生理和病理过程中起着重要作用，包括皮肤和肠上皮的更新，免疫系统功能，伤口愈合，以及癌症转移和心血管疾病。***在过去的二十年中，在理解调节定向细胞迁移的机制的复杂性方面取得了巨大的进展。这包括发现各种细胞外线索，如生化梯度、机械力、细胞外基质（ECM）刚度梯度和拓扑结构，这些都是引导迁移细胞的因素。另一个关键发现是识别信号通路，将个体环境信号转导为定向细胞运动。尽管如此，在同时呈现多种不同性质的线索的组织环境中，对调节定向细胞运动的分子机制知之甚少。在这里，我们建议通过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刚度景观，微流体来控制可溶性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参与者，并指导细胞在组织环境中的迁移。***本提案的具体目的包括：(1)在一种新的体外定向细胞迁移模型中确定化学和机械引导线索之间的串扰；(2)确定多种诱导信号共存环境下，化学和机械诱导信号串扰和细胞定向的分子机制。这项工作将阐明生化线索如何调节由物理梯度（ECM刚度）引导的细胞迁移。它还将识别整合生化和机械指导线索的信号通路，并动态调节细胞骨架网络，以在关键的生理或病理过程（包括肿瘤转移）中提供典型的细胞行为

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.**