Subcellular Mechanical Force Transduction

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DESCRIPTION (provided by applicant): This project focuses on the role that sub-cellular forces experienced at sites of adhesion between cells and their extracellular matrix play in regulating cell organization and function. The adaptive process by which cells spatially resolve and respond to such localized forces is critical to the adhesion remodeling required for cell motility, where cells reinforce specific adhesions while disassembling others. Previous work in this area has shown that focal adhesions assemble in response to forces applied to them, but because adhesion to extracellular matrix also induces biochemical signals that trigger cell contractility, it remains unclear whether forces applied to specific adhesions result in any mechanical crosstalk with the remaining adhesions distributed throughout the cell. This project will combine the expertise of 2 investigators to employ a new technique that simultaneously allows local mechanical stimulation of the adherent surface of a cell and spatially-resolved measurement of the local force fields generated throughout the cell in response to this stimulation. It is proposed that the relationship between local stimulation and global mechanical response is critical to the mechanical coordination within the cytoskeleton required for cell motility. 1 of the investigators has recently developed a technique wherein the deflections of an array of microfabricated posts report the cytoskeletal tension and local force fields generated by a cell attached to the array. In this project, nanoengineered magnetic material embedded in individual posts will be used to deform those posts, thereby exerting tunable subcellular mechanical stresses to attached cells, while the effects of the these stresses are simultaneously measured by the surrounding posts. Specific Aim 1 of the project will be to characterize the ability of the magnetic post device to apply well-defined forces at the nanonewton level to cells, to calibrate these forces, and to demonstrate the transmission of stresses to the cells. Specific Aim 2 will be to measure the global response of a cell to local forces through studies of changes in contractility and in the distribution of cellular forces, Specific Aim 3 will be to measure the non-local response of focal adhesions to locally applied forces, to determine whether focal adhesions re-distribute globally as a result of the distributed changes in cellular forces, and to determine how focal adhesion distributions vary as a function of the strength of a locally applied force. Development of this novel technique will lead to new understanding of how mechanical stresses are transduced by cells into an adaptive, coordinated cytoskeletal response, and will open a pathway toward new insights into the mechanisms of cell motility critical for inflammation, cancer metastasis, and tissue development.