Facultat de Física

Departament de Física de la Matèria Condensada

Biomechanical modeling of the migration polarity in cells

Andreu Fernández Gallén

CIRB Collège de France.

Neutrophils are a common cell in our system, which specializes in moving around in search of harmful elements in our bodies. These cells can be modeled as a composite cell surface composed of a cell membrane, an actin cortex, and special proteins that link these two surfaces together. These cells also use two special signaling proteins for migration. We explore the mechanism for cell polarization involving the interplay between Rho and Rac proteins, a well-known pair of antagonistic regulators of cytoskeletal dynamics. Unlike traditional reaction-diffusion wave-pinning models, which rely on shuttling between active and inactive forms of Rho GTPases, our model emphasizes local mutual inhibition as a bistable switch. The model incorporates mechanical interactions between the cell membrane and the cortex, where membrane tension plays a key role in Rho activation. Inspired by experimental observations of our collaborators, we integrate cortical dynamics, membrane mechanics, and membrane-cortex attachment (MCA), which influence the cell surface behavior. The resulting mechanochemical model is simulated using finite-element methods and compared to our collavorators experimental results, providing insights into the spatial-temporal regulation of cell polarization.