Motifs within genetic regulatory networks increase organization during pattern formation

Abstract

Motifs are small gene interaction networks that frequently occur within larger genetic regulatory networks (GRNs). However, it is unclear what evolutionary and developmental advantages motifs provide that have led to this enrichment. This study seeks to understand how motifs within developmental GRNs influence the complexity of multicellular patterns that emerge from the dynamics of the regulatory networks. A computational study was performed by creating Boolean intracellular networks with varying inserted motifs within a simulated epithelial field of embryonic cells. Each cell contains the same network and communicates with adjacent cells using contact-mediated signaling. Comparison of random networks to those with motifs demonstrated that: (1) Bistable switches that encode mutual inhibition simplify both the pattern and network dynamics. (2) All other motifs with feedback loops increase information complexity of the multicellular patterns while simplifying the network dynamics. (3) Negative feedback loops affect the dynamics complexity more significantly than positive feedback loops. (4) Feed forward motifs without feedback have little effect on the complexity of patterns formed.