Mechanochemical patterns in the cell cortex and the energy partitioning principle

Intracellular patterns are essential indicators of cellular functionality and the fate of cells. Dynamic phenomena such as spatiotemporal oscillatory actin waves, coupled with signaling pathways, drive fundamental processes such as cytokinesis. To unravel the physical principle underlying these intracellular patterns, we investigated the thermodynamic law that governs the energy partitioning in the cell-division-associated mechanochemical waves in the cell cortex. We measured the entropy production rate of both chemical and mechanical subsystems of the cell cortex across a variety of patterns as the system is driven further from equilibrium. We did this by manipulating the Rho GTPase pathway, which controls the cortical actin filaments and myosin-II. Our result indicates that allocation of energy depends on the system’s distance from thermodynamic equilibrium: near equilibrium, Onsager reciprocity is obeyed, there is proportional energy partitioning between the chemical and mechanical subsystems; Far from equilibrium, reciprocity is broken, the competing time-scales determines a differentiated energy partitioning.