Chemotactic cells establish cell polarity in the absence of external guidancecues. Such self-organized polarity is induced by spontaneous symmetry breakingin the intracellular activities, which produces an emergent memory effectassociated with slow-changing mode. Therefore, spontaneously establishedpolarity should play a pivotal role in efficient chemotaxis. In this study, wedevelop a model of chemotactic cell migration that demonstrates the connectionbetween intracellular polarity and chemotactic accuracy. Spontaneous polarityformation and gradient sensing are described by a stochastic differentialequation. We demonstrate that the direction of polarity persists over acharacteristic time that is predicted to depend on the chemoattractantconcentration. Next, we theoretically derive the chemotactic accuracy as afunction of both the gradient sensing ability and the characteristic time ofpolarity direction. The results indicate that the accuracy can be improved bythe polarity. Furthermore, the analysis of chemotactic accuracy suggests thataccuracy is maximized at some optimal responsiveness to extracellularperturbations. To obtain the model parameters, we studied the correlation timeof random cell migration in cell tracking analysis of Dictyostelium cells. Aspredicted, the persistence time depended on the chemoattractant concentration.From the fitted parameters, we inferred that polarized Dictyosteium cells canrespond optimally to a chemical gradient. Chemotactic accuracy was almost 10times larger than can be achieved by non-polarized gradient sensing. Using theobtained parameter values, we show that polarity also improves the dynamicrange of chemotaxis.
展开▼
