Cell-Cell Adhesion Mechanics and Mechanotransduction at the Single Cell Level

为了让细胞与相邻细胞保持连接，细胞与细胞之间存在着“黏附复合体”。这些复合体是细胞表面的一部分，由非常大的粘性分子组成，它们在细胞之间传递力，并将它们结合在一起。黏附复合体上的机械耦合对于细胞的许多健康行为是必要的。黏附复合体结构的变化或分子在拉伸过程中如何改变形状会导致心脏疾病、关节疾病(关节炎)，这是癌症细胞故事的一部分。细胞-细胞连接也是细胞检测对组织的力有多大的能力的一部分(机械转导)。细胞之间的这种连接的一种类型是桥粒，它连接到细胞内的纤维网络来传递力量，由于之前大多数黏附复合体的研究都是在黏附连接上进行的，它具有不同的分子，与不同的疾病有关，因此人们对它的了解还不是很清楚。这项研究项目将缩小关于桥粒在机械转导和疾病控制中的潜在作用的巨大知识鸿沟。这项研究将进一步推动美国发展所需的基本知识，以了解并最终治疗因桥粒未能正常发挥功能而导致的医疗状况。这项研究将与内布拉斯加大学现有的教育项目相结合，为本科生提供力学、机器人和细胞生物学方面的经验。PIS还将把研究方法转化为一门新的课程--“细胞力学”，以便将生物工程密集的知识带入当前的课程。PI小组的数据已经证明了桥粒-中间丝连接在调节细胞力学中的作用，这一作用长期以来一直被认为只属于粘附素连接。这项研究将确定桥粒在细胞-细胞黏附机制和机械转导中所起的作用。为了实现这一目标，将开发一种新的设备，通过定义的机械张力提供细胞-细胞连接的原位刺激和询问。该平台将能够拉伸一对细胞的相互连接并同时进行机械测量，这将解决目前在询问细胞-细胞粘附力方面的挑战(即，难以施加定义的机械刺激并同时进行机械测量)。更重要的是，集成在成像系统中，在施加负载的情况下，可以实时监测机械刺激对细胞-细胞交界处机械转导路径的影响。有了这个平台，两个基本的科学问题将得到解答：(1)桥粒及其与中间细丝的联系在维持细胞与细胞之间的黏附强度方面有何贡献；(2)桥粒连接是否包括机械传感器，将应用的机械信号转化为生化信号来调节细胞行为？该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

For cells to remain attached to their neighbors, there are cell-cell 'adhesion complexes.' These complexes are parts of the cell surface made up of very large adhesive molecules that transfer forces between the cells and hold them together. Mechanical coupling at adhesion complexes is necessary for many of the healthy behaviors of cells. Changes in the structure of the adhesion complex or of how the molecules change shape during stretching can cause diseases of the heart, joints (arthritis), and is part of the cellular story in cancer. The cell-cell junctions also are part of the cell's ability to detect how large the forces are on the tissue (mechanotransduction). One type of these junctions between cells, the 'desmosome', connects to the fiber network inside the cell to transmit forces and is not understood very well since most previous adhesion complex research has been done on the 'adherens' junction, which has different molecules and is associated with different diseases. This research project will reduce the huge knowledge gap about desmosomes with respect to their potential roles in mechanotransduction and disease control. The research will further the goals of the United States in developing the basic knowledge needed to understand and eventually treat medical conditions that are caused by failure of the desmosome to properly function. The research study will be integrated with existing University of Nebraska educational programs to offer undergraduate students experiences in mechanics, robotics, and cell biology. The PIs will also translate the research methodologies into a new course, "Cell Mechanics", in order to bring bioengineering-intensive knowledge into the current curriculum.Data from the PI's group have demonstrated the role of the desmosome-intermediate filament linkage in regulating cell mechanics, a role that has long been regarded to belong solely to the adherens junction. The research will determine the role that desmosomes play in cell-cell adhesion mechanics and in mechanotransduction. To achieve this goal, a novel device will be developed to provide in situ stimulation and interrogation of cell-cell junctions through defined mechanical tension. The platform will be able to stretch the mutual junction of a single pair of cells and simultaneously perform mechanical measurement, which will address the current challenge in interrogating cell-cell adhesion (i.e., difficulties in applying defined mechanical stimuli and conducting mechanical measurements at the same time). More importantly, integrated within an imaging system, the effect of mechanical stimuli on mechanotransduction pathways at the cell-cell junction can be monitored in real-time under applied load. With the platform, two fundamental scientific questions will be answered: (1) what is the contribution of desmosome and its link to intermediate filaments in maintaining cell-cell adhesion strength and (2) does the desmosome junction include mechanosensors that convert applied mechanical cues into biochemical signals to regulate cell behavior?This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.