The vertebrate-specific VENTX/NANOG gene empowers neural crest with ectomesenchyme potential

Abstract

During Cambrian, unipotent progenitors located at the neural (plate) border (NB) of an Olfactoria chordate embryo acquired the competence to form ectomesenchyme, pigment cells and neurons, initiating the rise of the multipotent neural crest cells (NC) specific to vertebrates. Surprisingly, the known vertebrate NB/NC transcriptional circuitry is a constrained feature also found in invertebrates. Therefore, evidence for vertebrate-specific innovations endowing vertebrate NC with multipotency is still missing. Here, we identified VENTX/NANOG and POU5/OCT4 as vertebrate-specific innovations. When VENTX was depleted in vivo and in directly-induced NC, the NC lost its early multipotent state and its skeletogenic potential, but kept sensory neuron and pigment identity, thus reminiscent of invertebrate NB precursors. In vivo, VENTX gain-of-function enabled NB specifiers to reprogram embryonic non-neural ectoderm towards early NC identity. We propose that skeletogenic NC evolved by acquiring VENTX/NANOG activity, promoting a novel multipotent progenitor regulatory state into the pre-existing sensory neuron/pigment NB program.

Insights Into the Early Gene Regulatory Network Controlling Neural Crest and Placode Fate Choices at the Neural Border

“…However, this model is debated since single-cell transcriptomes have shown that the multipotency gene signature proposed by Buitrago-Delgado et al was not specific to multipotent cells (Briggs et al, 2018). Rather, functional analysis of the vertebrate-specific genetic innovations Nanog/Oct4 (and their orthologs Ventx/ Pou5) before or after gastrulation rather suggests that NC progenitors de novo activate pluripotency regulators after NB induction (Scerbo and Monsoro-Burq, 2020). This reinitiates multipotency and promotes the ectomesenchyme fate.…”

“…This reinitiates multipotency and promotes the ectomesenchyme fate. From an evolutionary perspective, the cranial NB/NC-GRN requires Ventx/Nanog, Pou5/Oct4 and later NC specifier Ets1 to promote jawed structures formation in gnathostomes (Simoes-Costa and Bronner, 2016;Martik et al, 2019;Soldatov et al, 2019;Scerbo and Monsoro-Burq, 2020). Later on, NC specifiers' downregulation leads to the loss of pluripotency and the initiation of cell differentiation (Dottori et al, 2001;Sasai et al, 2001;Teng et al, 2008;Betancur et al, 2010;Mundell and Labosky, 2011;Dupin et al, 2018).…”

On the road again: Establishment and maintenance of stemness in the neural crest from embryo to adulthood

“…Ventx2 is broadly expressed in the neural plate border. 170 Knockdown of Ventx2 selectively affected expression of the NC specifiers Snail2, Sox9, Sox10, and Twist1 whereas Myc, Tfap2a, and Foxd3 levels were unaffected. 170 This altered expression profile resulted in reduced migration to the pharyngeal arches and reduced craniofacial skeleton whereas the neuronal lineage was unaffected in vivo and in vitro (in comparison, the melanocytic lineage was affected in vitro but not in vivo).…”

“…170 This altered expression profile resulted in reduced migration to the pharyngeal arches and reduced craniofacial skeleton whereas the neuronal lineage was unaffected in vivo and in vitro (in comparison, the melanocytic lineage was affected in vitro but not in vivo). 170 Furthermore, ectopic NC cells that were not biased toward any certain fate were formed in the ectoderm lateral to the NC domain in a process that required Ventx2, thus suggesting a role for Ventx2 in enabling the NC with a broader potential than just being restricted to neural derivatives, which would be the default for an ectodermal cell population. 170…”

“…170 Furthermore, ectopic NC cells that were not biased toward any certain fate were formed in the ectoderm lateral to the NC domain in a process that required Ventx2, thus suggesting a role for Ventx2 in enabling the NC with a broader potential than just being restricted to neural derivatives, which would be the default for an ectodermal cell population. 170…”