Modulation of cross-linked actin networks by pH

How cells orchestrate their complex cytoskeleton precisely in space and time is still far from understood. Recent studies suggest that local and transient variations of intracellular pH are critically involved in many important cytoskeletal processes. Yet, little is known about which proteins contribute to the pH sensitivity of cytoskeletal structures. Using macrorheology and confocal microscopy we investigate how a variation of pH affects structural and mechanical properties of reconstituted cross-linked actin systems. We demonstrate that each of the three cross-linking proteins tested here - cortexillin, filamin and fascin - shows a distinctive pH dependence. Our results indicate that cross-linked actin structures constitute ideal targets for the generation of specific morphogenetic cellular responses by varying the intracellular pH. This also highlights the amazing flexibility and adaptability of a heterogeneous set of cytoskeletal structures in response to a single effect, such as the variation of pH.