Cells move in a complex three-dimensional environment composed of fibrous proteins. A first step for a cell in choosing a direction to move is to sense its environment by tugging at the fibers. This starts what is called 'cell contractility.' How contractility is achieved on fibers of varying diameters distributed randomly or in specific patterns, in normal or diseased tissues, is mostly unknown. Understanding the first sensory interactions between a cell and a contacted fiber is important to how cells invade a fibrous tissue, such as when cancer cells leave a tumor, or in directed migration of cells on fibers towards a wound site. Most of what we know about cell migration stems from classical studies conducted on 2D flat substrates or, more recently, using complex gels. Neither approach allows the studying of cell-fiber interactions. This research will address the need to quantify cell-fiber interactions to understand cell migration during wound healing and disease. In this collaborative research, by combining state-of-art technologies in nanofiber manufacturing, cell signaling biosensors, and cell mechanics, we will be able to see inside the cell and determine the decision mechanisms that help cells migrate along fibers. The PI will work with faculty at a local community college to train them in the laboratory so that they can develop educational materials. This will create research opportunities for community college students.

This project will define the mechanobiological state of a cell as it interacts with fibers. Specifically, we will reveal RhoGTPase signaling (RhoA, Rac1, and CdC42) as cells form protrusions and migrate on fibers. The interplay, localization, and summation of these molecules at specific regions of the cell define the mode of migration, which has been shown to be different in 2 and 3D. To determine the activity maps of these proteins in cells on fibers, we will design fiber networks of varying diameters (nanometers-microns) distributed in aligned and random configurations signifying pro- and anti-invasive conditions. In doing so, we will be able to pinpoint spatial and temporal activation maps of RhoGTPase's as cells tug and exert forces on fibers. The mechanobiological force quantitation-biosensor activation will develop new knowledge in the plasticity of cell migration to changing fibrous environments, as would be encountered in vivo. Linking adhesion receptor-based signaling spanning a wide range of spatial (nanometers-microns) and temporal (seconds-hours) scales with migration and force modulation will provide new knowledge in invasion-driven cell migration, thus opening new directions in drug discovery and development.

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.

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