Membrane curvature sensing-mediated ultrafast traveling wave of cortical proteins

Immune cells exhibit stimulation-dependent traveling waves within the cortex, much faster than typical cortical actin waves. These waves reflect rhythmic assembly of both actin machinery and periphery membrane proteins such as F-BAR domain-containing proteins. Combining theory and experiments, we develop a mechanochemical feedback model involving membrane shape changes and F-BAR proteins that render the cortex an interesting dynamical system. We show that such cortical dynamics can manifest itself as ultrafast traveling waves of cortical proteins, in which the curvature sensitivity-driven feedback always constrains protein lateral diffusion in wave propagation. The resulting protein wave propagation mainly reflects the spatial gradient in the timings of the local protein recruitments from cytoplasm. We provide evidences that membrane undulations accompany such rhythms, excite further cortical activation, and potentiate propagation beyond the initial cortical activation site. Therefore, membrane shape change and protein curvature sensitivity have underappreciated roles in setting high-speed cortical signal transduction rhythms.