Early induction of the neural crest.

MAYOR R.; VILLANUEVA S.; AYBAR M. J.; GLAVIC A.; ACUÑA G.; TRIBULO C.; HONORÉ S. M.; BASTIDAS F.; RODRIGUEZ E.

Valle Nevado

Congreso; First International Meeting of the Latinamerican Society of Developmental Biology; 2003

Latinamerican Society of Developmental Biology

The neural crest segregates from the dorsal portion of the neural tube and migrates through the embryo to generate a highIy pluripotent celI population, able to generate a variety of celI types. The specification of the neuraI crest depends on signaIs received from the surrounding environment that activate a genetic cascade of celI differentiation. The celIular and molecular mechanism that control neural crest induction and differentiation are only now beginning to be unraveled. We will present data that support a model of neuraI crest induction in three steps. We have characterized the first step of neuraI crest induction as the specification of the entire border of the neural plate as anterior neural fold. This step depends on a gradient concen­tration of BMP and at a specific threshold of BMP this anterior neural fold is induced. In the second step additional signals such as Wnts, FGF and retinoic acid transform the most posterior region of the anterior neuraI fold into prospective neural crest celIs. We will show evidence that this transformation, correspond, at least in part, to the posteriorizing signaIs that works on the neuraI plate. In this second step the Notch/Delta signaling plays an important role on the specification of the borders of the neural crest territory. The third step, that takes place once the neural tube is closed, requires higher values of BMP, as an inhibition on BMP activity at this step Ieads to a decreasing in the express ion of the neural crest markers. The combination of alI these signals at different steps leads to the activation of specific genes in the neural crest celIs. We have shown that some of these genes work in the specification of the neural crest (like Snail) while others work as survival factors (like Slug, Sox10). A final model where all these extracelIular signaIs and transcription factors are considered will be discussed.