Nonequilibrium assembly, maintenance and control of a system of Golgi cisternae in the trafficking pathway

How do cellular organelles, such as the Golgi, self-assemble to a specific steady state size and maintain it in the face of a steady trafficking of vesicles? We address this nonequilibrium assembly using a Master equation approach that involves the mechanochemical cycle of active fission-fusion. This gives rise to nonlinear dynamical equations with feedback control for the cisternal masses. These dynamical equations exhibit a variety of phases, such as stable cisternae and limit cycles, that we identify with vesicular transport, cisternal progression and cisternal dissolution. We show that the homeostatic balance can be disrupted by sudden spurts of material influx; in this case, we propose control strategies that may be operative to restore the assembly to the vicinity of the homeostatic set point.