Neuromesodermal progenitor origin of trunk neural crest in vivo

Neural crest (NC) is a vertebrate-specific population of multipotent embryonic cells predisposed to diverse derivatives along the anteroposterior (A-P) axis. Only cranial NC progenitors give rise to ectomesenchymal cell types, whereas trunk NC is biased for neuronal cell fates. By integrating multimodal single-cell analysis, we provide evidence for divergent embryonic origins of cranial vs. trunk NC that explain this dichotomy. We show that the NC regulator foxd3 is heterogeneously expressed across the A-P axis and identify its specific cranial and trunk autoregulatory enhancers. Whereas cranial-specific enhancer is active in the bona fide NC, the trunk foxd3 autoregulatory element surprisingly marked bipotent tailbud neuromesodermal progenitors (NMps). We integrated NMp single cell epigemomics and trasncriptomics data and for the first time reconstructed anamniote NMp gene regulatory network. Moreover, using pseudotime and developmental trajectory analyses of NMps and NC during normal development and in foxd3 mutants, we demonstrate an active role for foxd3 in balancing non-cranial NC and NMp fates during early embryonic development. Strikingly, we show that a portion of posterior NC in the developing zebrafish embryo is derived from the pro-neural NMps. This suggests a common embryonic origin of trunk NC and NM progenitors that is distinct from cranial NC anlage, and elucidates pro-neural bias of trunk NC. ### Competing Interest Statement The authors have declared no competing interest.