This study is done using impact of stochasticity on gene regulation networks, using the cell-to-cell communication mechanism in Escherichia coli as an example. First we explored signal mediated positive autoregulation networks and their stochastic bistability, in the presence of which an initially homogeneous cell population would evolve into two distinct subpopulations. We proposed the simplification of the full network into one that can be theoretically studied. Simulation results indicate the simplifications retain the bistability and the distribution shapes so that the simplified network can be used to predict the bistable behavior of the full network.
Moreover, it was shown that the bistability can be influenced by the signal molecule number, and that stochastic simulation is necessary for bistable systems. The self-promotion network for SdiA protein, with the autoinducer-2 (AI-2) signal molecule, was used as an example. The results further motivate the need for modeling of the AI-2 uptake mechanism. We next explored cell age distribution in the case where the number of a key protein for cell division has a stochastic bifurcation. With this bifurcation, the alive probability function (the probability that the cell has not divided) can be written in a double-exponential form.
Author:- Fang, Xin