Shared features of blastula and neural crest stem cells evolved at the base of vertebrates.

The neural crest is vertebrate-specific stem cell population that helped drive the origin and evolution of the vertebrate clade. A distinguishing feature of these stem cells is their multi-germ layer potential, which has drawn developmental and evolutionary parallels to another stem cell population-pluripotent embryonic stem cells (animal pole cells or ES cells) of the vertebrate blastula. Here, we investigate the evolutionary origins of neural crest potential by comparing neural crest and pluripotency gene regulatory networks (GRNs) in both jawed ( ) and jawless (lamprey) vertebrates. Through comparative gene expression analysis and transcriptomics, we reveal an ancient evolutionary origin of shared regulatory factors between neural crest and pluripotency GRNs that dates back to the last common ancestor of extant vertebrates. Focusing on the key pluripotency factor (formerly oct4), we show that the lamprey genome encodes a ortholog that is expressed in animal pole cells, as in jawed vertebrates, but is absent from the neural crest. However, gain-of-function experiments show that both lamprey and enhance neural crest formation, suggesting that was lost from the neural crest of jawless vertebrates. Finally, we show that is required for neural crest specification in jawed vertebrates and that it acquired novel neural crest-enhancing activity after evolving from an ancestral -like clade that lacks this functionality. We propose that a pluripotency-neural crest GRN was assembled in stem vertebrates and that the multi-germ layer potential of the neural crest evolved by deploying this regulatory program.