About 500 million years ago, a new type of adaptive immune defense emerged in basal jawed vertebrates, accompanied by morphological innovations, including the thymus. Did these evolutionary novelties arise de novo or from elaboration of ancient genetic networks? We reconstructed the genetic changes underlying thymopoiesis by comparative genome and expression analyses in chordates and basal vertebrates. The derived models of genetic networks were experimentally verified in bony fishes. Ancestral networks defining circumscribed regions of the pharyngeal epithelium of jawless vertebrates expanded in cartilaginous fishes to incorporate novel genes, notably those encoding chemokines. Correspondingly, novel networks evolved in lymphocytes of jawed vertebrates to control the expression of additional chemokine receptors. These complementary changes enabled unprecedented Delta/Notch signaling between pharyngeal epithelium and lymphoid cells that was exploited for specification to the T cell lineage. Our results provide a framework elucidating the evolution of key features of the adaptive immune system in jawed vertebrates.
We have not found any resources mentioned in this publication.
SciCrunch® is a data sharing and display platform. Anyone can create a custom portal where they can select searchable subsets of hundreds of data sources, brand their web pages and create their community. SciCrunch® will push data updates automatically to all portals on a weekly basis. User communities can also add their own data to SciCrunch®, however this is not currently a free service.