A protocol for unraveling gene regulatory networks.

Regulatory genes form large networks that are fundamental to the developmental program. The protocol presented here describes a general approach to assemble maps of gene regulatory networks (GRNs). It combines high-resolution spatio-temporal profiling of regulatory genes, strategies to perturb gene expression and quantification of perturbation effects on other genes of the network. The map of the GRN emerges by integration of these data sources and explains developmental events in terms of functional linkages between regulatory genes. This protocol has been successfully applied to regulatory processes in the sea urchin embryo, but it is generally applicable to any developmental process that relies primarily on transcriptional regulation. Unraveling the GRN for a whole tissue or organ is a challenging undertaking and, depending on the complexity, may take anywhere from months to years to complete.