Four different mechanisms for switching cell polarity
Fig 2
Schematic representation of the workflow.
A Switching signals are parameterized by the choice of i) a reaction rate it acts on, ii) an inhibitory or enhancing effect and iii) the amplitude Xmax and duration τ of the transient signal. X can act on any of the 11 parameters of the polarity model. B Example of a deterministic and stochastic simulation before, during and after the signal. The signal is applied between t = 0 and t = 3. Thick lines indicate the concentrations of A (yellow), B (red), R (green) and X (purple) at pole 1, and thin lines at pole 2. C Switching is evaluated by comparing the signs of the asymmetry ωA(t) in A before and after the switch. For the stochastic simulation a switching probability is calculated from 100 trajectories. D Switching regimes are plotted in phase space as a function of Xmax and τ for the modification of each model parameter. For the deterministic model, successful switches are shown by the gray regions with a black outline, for the stochastic model switching probabilities are shown in green. E The state of the system during the signal is identified by simulating the deterministic model with the signal applied for the duration of the simulations. The dynamics is classified into three states: symmetric (blue), oscillatory (orange) and polarized (yellow).