Evolutionary plasticity of developmental gene regulatory network architecture

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 104; no. 49; pp. 19404 - 19409
• Main Authors: Hinman, Veronica F, Davidson, Eric H
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 04.12.2007; National Acad Sciences
• Subjects: Animals; Architecture; Asteroidea; Biological Sciences; Cambrian; Comparative studies; Control systems; Echinoderms; Echinoidea; Electrical circuits; embryogenesis; Embryonic growth stage; Embryos; Endoderm; Endoderm - growth & development; Evolution, Molecular; Evolutionary biology; Gene Regulatory Networks - physiology; Genes; Genomics; Invertebrates; Mesoderm; Mesoderm - growth & development; Receptors, Notch - genetics; Receptors, Notch - metabolism; regulator genes; Repression; Sea urchins; Sea Urchins - genetics; Sea Urchins - growth & development; seeds; Signal Transduction; Starfish; Starfish - genetics; Starfish - growth & development; T-Box Domain Proteins - genetics; T-Box Domain Proteins - physiology
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.0709994104

Sea stars and sea urchins evolved from a last common ancestor that lived at the end of the Cambrian, approximately half a billion years ago. In a previous comparative study of the gene regulatory networks (GRNs) that embody the genomic program for embryogenesis in these animals, we discovered an almost perfectly conserved five-gene network subcircuit required for endoderm specification. We show here that the GRN structure upstream and downstream of the conserved network kernel has, by contrast, diverged extensively. Mesoderm specification is accomplished quite differently; the Delta-Notch signaling system is used in radically distinct ways; and various regulatory genes have been coopted to different functions. The conservation of the conserved kernel is thus the more remarkable. The results indicate types of network linkage subject to evolutionary change. An emergent theme is that subcircuit design may be preserved even while the identity of genes performing given roles changes because of alteration in their cis-regulatory control systems.