Neural crest development in Xenopus requires Protocadherin 7 at the lateral neural crest border

Abstract

In vertebrates, the neural crest is a unique population of pluripotent cells whose development is dependent onsignalin g from neighbori ng tissues. Cadherin family members, including protocadherins, are emerging asmajor players in neural crest development, largely through their roles in cell adhesion and sorting in embryonictissues. Here, we show that Protocadherin 7 (Pcdh7), previously shown to function in sensorial layer integrityand neural tube closure in Xenopus, is also involved in neural crest specification and survival. Pcdh7 expressionpartly overlaps the neural crest domain at the lateral neural crest border. Pcdh7 knockdown in embryos does notalter neural crest induction; however, neural crest specification markers, including Snail2 and Sox9, are lost, dueto apoptosis of the neural crest starting after stage 13. Pcdh7 knockdown also results in downregulation ofWnt11b; both of which are co-expressed in the sensorial layer lateral to the neural crest, suggestive of a rolefor Wnt11b in the neural crest apoptosis. Confirming this role, apoptosis, Snail2 expression and the developmental fate of the neural crest can be partially rescued by ectopic expression of Wnt11b. These results indicate thatPcdh7 plays an important role in maintaining the sensorial layer at the lateral neural crest border, which is nec-essary for the secretion of survival factors, including Wnt11b