Evolutionary mechanisms underlying conservation and evolvability in regulatory networks

Aviv Regev
Bauer Center for Genomics Research
Harvard University


Transcriptional modules of co-regulated genes play a key role in regulatory networks. Comparative studies show that modules of co-expressed genes are conserved across taxa. However, little is known about the mechanisms underlying module evolution. Here, we explore the evolution of cis-regulatory programs associated with conserved modules by integrating expression profiles for two yeast species with sequence data of 15 other fungal genomes. We show that while the regulatory mechanisms accompanying certain conserved modules are strictly conserved, those of other conserved modules are remarkably diverged. In particular, we infer the evolutionary history of the regulatory program governing the ribosomal modules, showing how the infiltration of new cis-elements, the establishment of redundancy in the module's regulatory mechanism, and the loss of other cis-elements, allow the emergence of different regulatory mechanisms that perform similar functional roles. Our results illuminate the dynamics of promoter evolution and may help in understanding the evolvability and increased redundancy of transcriptional regulation in higher organisms.

Joint work with Amos Tanay and Ron Shamir (Tel Aviv University)