Krüppel-like factors play essential roles in regulating pluripotency and the formation of neural crest stem cells.

The evolution of complex vertebrate body plans was driven by the acquisition of the neural crest, a stem cell population that retains broad, multi-germ layer potential after most embryonic cells have become lineage restricted. We have previously shown that neural crest cells share significant gene regulatory architecture with pluripotent blastula stem cells. Here, we examine the roles that two Krüppel-like Family (Klf) transcription factors, Klf2 and Klf17, play in these cell populations. We found that inhibition of either klf2 or klf17 expanded expression of pluripotency, neural plate border and neural crest factors in neurula stage Xenopus embryos, suggesting that Klf factors regulate the exit from pluripotency and proper establishment of the boundary of the neural crest domain. To gain further insights into the role of Klf factors in the evolution of the neural crest, we examined their expression in sea lamprey, a jawless vertebrate, and show that ectopic expression of lamprey klf17 in Xenopus embryos phenocopies Xenopus klf17. These data suggest that klf17 may have been the ancestral Klf factor that functioned in these gene regulatory networks in stem vertebrates.