SUMMARY

Cell adhesion to extracellular matrices (ECM) is pertinent to differentiation, proliferation, migration, and apoptosis. Alterations in adhesive mechanisms are central to the behavior of cells in pathological conditions including cancer, atherosclerosis, and defects in wound healing. The composition and structure of focal adhesions, the site of contact between cell and ECM, is critical to the generation of adhesion-dependent functional responses. However, the mechanisms that dictate the generation of adhesive forces remain poorly understood. The objective of this project is to analyze the role of nanoscale organization of focal adhesions in cell adhesion strengthening to ECM. We hypothesize that the precise nanoscale organization of focal adhesion complexes regulates adhesive interactions through contact area “splitting” and integrin clustering. In this project, a rigorous analysis of adhesion strengthening using an integrated set of unique techniques to create engineered adhesion environments and to quantitatively analyze adhesion strength will provide new insights into the regulation of adhesive interactions. Nanopatterned arrays of cell adhesion proteins, in which the size, spacing, and area splitting of the adhesive interface is varied, will be combined with a spinning disk adhesion assay to quantitatively assess changes in adhesion strength that occur with modifications to the organization of the adhesion area. Integrin clustering will be explored as a mechanism to regulate cell adhesion through promotion of mature focal adhesion complex formation. Nanopatterned arrays of multi-valent integrin-specific FN ligands will be used to control the precise number of integrins present in a cluster. The outcome of this project is a new understanding of the underlying mechanisms regulating cell adhesive force and focal adhesion organization and function.