Excitation, oscillations and wave propagation in a G-protein-based model of signal transduction inDictyostelium discoideum

Abstract

In an earlier paper (Tang & Othmer 1994Math. Biosci120, 25-76), we developed a G-protein-based model for signal transduction in the cellular slime mouldDictyostelium discoideumand showed that it can account for the results from perfusion experiments done by Devreotes and coworkers (Devreoteset al.1979J. Cell.80, 300-309; Devreotes & Steck 1979J. Cell Biol.80, 300-309; Dinaueret al.1980 J. Cell Biol. 86, 537—561). The primary experimental observables are the amounts of cAMP secreted and the time scale of adaptation in response to various stimuli, and we showed that the predictions of the model agree well with the observations. Adaptation in the model arises from dual receptor-mediated pathways, one of which produces a stimulatory G protein Gsand the other of which produces an inhibitory G protein Gt. In this paper we use the model to simulate the suspension experiments of Gerisch & Wick (1975Biochem. biophys. Res. Commun.65, 364—370) and the experiments done in cell cultures on Petri dishes (Tomchik & Devreotes 1981Scien, Wash.212, 443-446). The model predicts excitation to cAMP stimuli, sustained oscillations, or spiral waves and target patterns, depending on the developmental stage of the cells and experimental conditions. The interaction between different pacemakers is also studied.