Title: "Cellular responses to mechanical stimuli via different adhesion complexes and different cytoskeletal filaments"

Committee:
Research Advisor/Chair: Dimitrije Stamenovic
Research Advisor/Co-Chair: Michael Smith
Paul Barbone
Ramaswamy Krishnan

Abstract:
In vivo, forces are applied to cells via a diverse extracellular matrix composed of many types of adhesive proteins (e.g. collagen, fibronectin, laminin). Cells attach to these proteins with several specialized types of adhesion complexes, which in turn connect to different cytoskeletal networks. Here, we investigate how the mechanism of force transduction affects cell behavior. By culturing cells on different ECM ligands, we can control which transmembrane proteins and cytoskeletal filaments are used to transmit mechanical signals. The working hypothesis of this project is that the active, contractile actin cytoskeleton needs to be stimulated to initiate dynamic cell responses, (such as cell reorientation in response to stretch). On the other hand, the function of passive cytoskeletal networks (such as intermediate filaments), are for stability purposes only. In this project, we apply uniaxial strain to cells cultured on polyacrylamide gels micropatterned with different adhesive ligands – fibronectin (for actin stress fiber stimulation) and laminin (for intermediate filament stimulation). We also develop a novel technique for monitoring cell response to applied stretch. With this technique, termed biomechanical imaging, we are able to quickly generate detailed maps of cell stiffness and prestress. Results from this work will help to answer long standing questions about how cells interpret mechanical signals to orchestrate dynamic cell responses such as reorientation.