Evolution of Snail-mediated regulation of neural crest and placodes from an ancient role in bilaterian neurogenesis.

Evolution of Snail-mediated regulation of neural crest and placodes from an ancient role in bilaterian neurogenesis.
Dev Biol. 2019 Jun 15;:
Authors: York JR, Zehnder K, Yuan T, Lakiza O, McCauley DW
Abstract
A major challenge in vertebrate evolution is to identify the gene regulatory mechanisms that facilitated the origin of neural crest cells and placodes from ancestral precursors in invertebrates. Here, we show in lamprey, a primitively jawless vertebrate, that the transcription factor Snail is expressed simultaneously throughout the neural plate, neural plate border, and pre-placodal ectoderm in the early embryo and is then upregulated in the CNS throughout neurogenesis. Using CRISPR/Cas9-mediated genome editing, we demonstrate that Snail plays functional roles in all of these embryonic domains or their derivatives. We first show that Snail patterns the neural plate border by repressing lateral expansion of Pax3/7 and activating nMyc and ZicA. We also present evidence that Snail is essential for DlxB-mediated establishment of the pre-placodal ectoderm but is not required for SoxB1a expression during formation of the neural plate proper. At later stages, Snail regulates formation of neural crest-derived and placode-derived PNS neurons and controls CNS neural differentiation in part by promoting cell survival. Taken together with established functions of invertebrate Snail genes, we identify a pan-bilaterian mechanism that extends ...

Source: Developmental Biology - June 14, 2019 Category: Biology Authors: York JR, Zehnder K, Yuan T, Lakiza O, McCauley DW Tags: Dev Biol Source Type: research