Modelling the influence of cell signaling on the dynamics of gene regulatory networks

Boolean models have proven to be effective in capturing some features of the dynamical behavior of the gene regulatory network of isolated cells. Cells are however constantly exposed to several signals that affect the regulation of their genes and are therefore not isolated. Moreover, cells in multi-cellular organisms and, to some extent, also in colonies of unicellular ones modify their gene expression profiles in a coordinated fashion. Many of these processes are controlled by cell–cell communication mechanisms. It appears therefore important to understand how the interplay among gene regulatory networks, by means of the signaling network, may alter their dynamical properties. In order to explore the issue, a model based on interconnected identical Boolean networks has been proposed, which has allowed to investigate the influence that cell-signaling may have on the expression patterns of individual cells, with particular regard on their variety and homeostasis. The main results described in this chapter show that both the diversity of emergent behaviors and the diffusion of perturbations may not depend linearly on the fraction of genes involved in the signaling network. On the contrary, when cells exchange a moderate quantity of signals with neighbors, the variety of their activation patterns is maximized, together with the number of genes that can be damaged as a consequence of a minor alteration of the system