Maintenance of Mechanical Tension for Normal Tissue Function Requires Intercellular Cooperation

机械应力影响生物的形态和功能。为了正常的功能，组织必须将压力维持在理想的水平，这一过程被称为张力动态平衡。包括损伤、饮食、衰老和遗传危险因素在内的各种因素可能会破坏张力稳态，而稳态的丧失会促进疾病的进展，包括动脉粥样硬化、动脉瘤气球的形成、急性肺损伤和癌症。虽然人们普遍认为张力稳态跨越了广泛的长度范围，即使是孤立的单个细胞也能够维持张力稳态，但初步数据表明，孤立的细胞不能维持张力稳态，需要细胞间的合作。该奖项将调查细胞间的合作如何有助于张力稳态，并确定潜在的生物物理和生化机制。该项目将专注于血管内皮细胞的动态平衡，因为血管疾病与张力动态平衡的丧失有关。这项研究的结果将对我们理解张力稳态丧失与动脉粥样硬化和动脉瘤等疾病进展之间的功能联系产生革命性的影响。此外，我们的研究结果可能为诸如癌症之类的疾病提供洞察力，在这些疾病中，张力稳态的丧失是疾病进展的标志。这项工作将涉及本科生和研究生，并将被整合到课程中。血管生物学的主导范式是，通过对细胞内力学的反馈控制和对外部施加的压力做出反应的信号，在多个长度(和时间)尺度上存在张力动态平衡。然而，这项研究的初步数据显示，孤立的细胞不能维持张力性内稳态，而融合的多细胞集群可以，这表明细胞-细胞相互作用可能是内稳态所必需的。这导致了一个可行的假设，即细胞与细胞之间的直接相互作用是维持内皮细胞张力内稳态所必需的。这要么是通过相邻细胞之间的机械相互依赖，要么是通过粘连连接和焦点粘连之间的分子串扰来实现的。为了验证这一假设，将使用由PI开发的微图案牵引显微镜系统来测量细胞团和单个细胞中的牵引力。这项技术利用多个不同的黏附配体，并与模拟体内拉伸条件的底物应变应用、模拟血管壁切应力的剪切流应用、可调节的底物刚性和高分辨率显微镜应用兼容，以测量精度低于1 NN的细胞牵引力。

Mechanical stresses influence biological form and function. For normal functions, tissues must maintain stress at a preferred level a process known as tensional homeostasis. Various factors including injuries, diet, aging and genetic risk factors may disrupt tensional homeostasis, and loss of homeostasis promotes the progression of diseases including atherosclerosis, formation of aneurysm balloons, acute lung injury, and cancer. Although it is widely believed that tensional homeostasis traverses a wide range of length scales and that even single cells in isolation are capable of maintaining tensional homeostasis, preliminary data indicate that isolated cells are not capable of maintaining tensional homeostasis and that intercellular cooperation is required. This award will investigate how intercellular cooperation contributes to tensional homeostasis and to determine the underlying biophysical and biochemical mechanisms. The project will focus on homeostasis in vascular endothelial cells since vascular diseases are linked to a loss of tensional homeostasis. Results from this study will have a transformative impact on our understanding of the functional link between loss of tensional homeostasis and progression of diseases such as atherosclerosis and aneurysm. Furthermore, results of our study may provide insight into diseases such as cancer where the loss of tensional homeostasis is a hallmark of disease progression. The work will involve both undergraduate and graduate students and will be integrated into coursework.The dominant paradigm in vascular biology is that tensional homeostasis exists across multiple length (and time) scales through the feedback control of intracellular mechanics and signaling in response to the externally imposed stresses. However, preliminary data from this study revealed that isolated cells could not maintain tensional homeostasis, whereas confluent multicellular clusters could, suggesting that cell-cell interactions might be necessary for homeostasis. This leads to a working hypothesis that direct cell-cell interactions are required for maintaining tensional homeostasis in the endothelium. This is accomplished either via mechanical interdependence between adjacent cells, or via molecular crosstalk between adherens junctions and focal adhesions. To test this hypothesis, traction forces in cellular clusters and in individual cells will be measured using a micropattern traction microscopy system that was developed by the PIs. This technique utilizes multiple, distinct adhesion ligands and is compatible with substrate strain application mimicking the stretch conditions in vivo, application of shear flow mimicking vascular wall shear stress, tunable substrate rigidity, and high resolution microscopy to measure cellular traction forces with less than 1 nN accuracy.