Predictive multi-scale model of focal adhesion-based durotaxis

项目摘要 这项建议的总体目标是建立预测性的多尺度数学模型来破译 多药耐药机制。趋杜性是细胞向更硬的细胞外基质(ECM)迁移的偏好，并具有 在许多生物学过程中发挥重要作用，从胚胎发育到肿瘤转移。焦点粘连(FA) 是趋杜性的功能单位；它是一种基于整合素的多蛋白跨膜连接，细胞通过它施加肌动蛋白。 基于细胞骨架的牵引力，以拖拽ECM并感觉其刚性。尽管与生物医学高度相关 应用方面，目前还不清楚FA如何在很大程度上介导ECM硬度的机械传感和驱动趋性。 因为预测数学模型落后于该领域的描述性实验发现。在单FA级别， 虽然以前的模型解释了FA机械传感中的分子离合器行为，但它们无法解释FA是如何以及为什么- 局部蛋白质活动通过独特的时空模式(类似于足迹)来适应环境 已证明对多药耐药是必不可少的。足总本地化“足迹”的全部潜在机制及其确切意义 因此，在多药耐药中的作用尚不清楚。此外，趋性必须协调细胞体的移动和突起/回缩。 单元格边缘。当FA介导的牵引力驱动细胞体时，FA定位的机械传感事件如何协调 与细胞边缘的动力学是未知的。最后，在单细胞水平上，在不同发育阶段存在许多FAs。 任何时候都可以。目前尚不清楚该细胞如何整合单个FA的机械感知活动来驱动多药趋向性。 有意义地参与实验的预测模型是可取的，并且可能掌握着破译的关键 多药趋向性。为了实现这一目标，我们已经并将在迭代对话中以独特的方式将数学建模与 实验测试。中心假设是：牵引力产生的FA局部化时空动力学和 传递定义了FA介导的机械感觉和多药趋向性。这项建议的基础是我们以前的发现。我们 建立了第一个捕捉整个FA成熟过程本质的数学模型。也就是说，FA是从一个 新生复合体，向心性生长的FA，将分支肌动蛋白网络的逆行流动连接到成熟的 将应力纤维(SF)介导的收缩传递到ECM的FA。该模型唯一地将FA-本地化的FINE 从FA成熟过程中出现的蛋白质活性特征到FA机械传感事件。该模型预测了 并从实验上证实了FA接合SF的伸长率和伸缩性之间的负反馈 基于FA局部化的牵引振荡和ECM刚度的机械传感。在这些发现的推动下，我们的 具体目标是确定：1)FA力传递和SF延伸率在FA机械传感中的串扰；2)如何 FA机械感觉影响细胞边缘突起/收缩，以及3)细胞如何整合单个FA的机械感觉 来推动多药耐药。如果成功，拟议研究将提供一个解释数据和指导的量化平台 趋杜性实验设计，具有多尺度分辨率，从FA-局域动力学、细胞边缘 突起/收缩，在整个细胞水平上对细胞运动的影响。

Project Summary The over-arching goal of this proposal is to establish the predictive multi-scale mathematical model to decipher the mechanism of durotaxis. Durotaxis is the preference of cells migrating toward a stiffer extracellular matrix (ECM) and has important roles in many biological processes, ranging from embryo development to tumor metastasis. Focal adhesion (FA) is the functional unit of durotaxis; it an integrin-based multi-protein transmembrane linkage, through which cell exerts actin cytoskeleton-based traction force to tug the ECM and sense the stiffness. Despite the high relevance to biomedical applications, it is not well understood how FA mediates mechanosensing of ECM stiffness and drives durotaxis, largely because predictive mathematical models lag behind the descriptive experimental finding in the field. At single-FA level, while previous models explain molecular-clutch behaviors in FA mechanosensing, they cannot explain how and why FA- localized protein activities adapt to environments by distinctive spatial-temporal patterns (akin to footprints) that are demonstrated to be essential for durotaxis. The full underlying mechanisms of the FA-localized “footprint” and its exact roles in durotaxis are thus unknown. Further, durotaxis must coordinate movements of cell body and protrusion/retraction of cell edge. While the FA-mediated tractions drive the cell body, how the FA-localized mechanosensing events coordinate with the cell edge dynamics is unknown. Last, at a single-cell level, there exist many FAs at different developmental stages at any time. It is not understood how the cell integrates the mechanosensing activities of individual FAs to drive durotaxis. A predictive model that meaningfully engages with experiments is desirable and likely holds the key to decipher durotaxis. Toward this goal, we have been and will uniquely integrate mathematical modeling in iterative dialogues with experimental testing. The central hypothesis is: FA-localized spatial-temporal dynamics of the traction force generation and transmission defines FA-mediated mechanosensing and durotaxis. The basis of this proposal is our previous findings. We built the first mathematical model that captures the essence of entire FA maturation process. That is, FA evolves from a nascent complex, the centripetally growing FA that couples the retrograde flux of branching actin network, to the mature FA that transmits the stress fiber (SF)-mediated contractions onto ECM. This model uniquely links the FA-localized fine features of protein activities – emerging from FA maturation process – to FA mechanosensing events. The model predicted and was experimentally confirmed that a negative feedback between the elongation and contractility of the FA-engaging SF underlies the FA-localized traction oscillation and mechanosensing of ECM stiffness. Ushered by these findings, our specific aims are to determine: 1) how FA force-transmission and SF elongation cross-talk in FA mechanosensing; 2) how FA mechanosensing affects cell edge protrusion/retraction, and 3) how cell integrates mechanosensation of individual FAs to drive durotaxis. If successful, the proposed research would provide a quantitative platform interpret data and guide durotaxis experimental designs, which has the multi-scale resolutions ranging from FA-localized dynamics, cell edge protrusion/retraction, to cell movement at whole-cell level.