From endocytosis to crawling motility, a vast array of cellular functions require the cytoskeleton to organize and remodel the intracellular space and surrounding membranes. Cytoskeletal filaments, such as actin, act as highly dynamic building materials. With the help of regulatory proteins, they self-assemble into structures that push forward membranous protrusions, serve as directed tracks for intracellular transport, or contract to pinch the cell in half or facilitate the cell's adhesion to and remodeling of its surrounding matrix.
We want to understand, broadly, how mechanical forces shape the growth of actin structures and how the molecular architecture of these structures influences their mechanical properties. How does the velocity of branched actin network growth respond to a resisting force? What are the viscoelastic properties of branched actin networks, and how do they change in response to applied forces? What is the role of network architecture in determining the behavior of an actin structure? How do individual components of actin networks, such as single filaments or actin-binding proteins, respond to mechanical forces? We are also interested in using minimal systems to discover the fundamental physical mechanisms that underlie more complex biological functions such as filopodium formation or cell cortex rearrangements.
To address these questions, we use fluorescence microscopy, image analysis, surface patterning and AFM techniques and develop new AFM-based technology. We also collaborate with the Mullins Lab (UCSF) to study the force-dependent biochemistry of dendritic actin nucleation, and with the Geissler Group (UCB) to create simulations that help us understand how thermal fluctuations shape the complex elastic properties of actin networks and actin-membrane interactions.