Early induction of the neural crest

R. MAYOR; S. VILLANUEVA; M .AYBAR; A. GLAVIC; G. ACUÑA; C. TRÍBULO; S. M. HONORÉ; F. BASTIDAS; E. RODRÍGUEZ

Valle Nevado, Chile

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 highly pluripotent cell population, able to generate a variety of cell types. The specification of the neural crest depends on signals received from the surrounding environment that activate a genetic cascade of cell differentiation. The cellular and molecular mechanisms that control neural crest induction and differentiation are only now beginning to be unravelled. We will present data that support a model of neural crest induction in three steps. We have characterized the first step of neural 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 neural fold into prospective neural crest cells. We will show evidence that this transformation correspond, at least in part, to the posteriorizing signals that works on the neural plate. In this second step the Notch/Delta signalling 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 leads to a decreasing in the expression of the neural crest markers. The combination of all this signals at different steps leads to the activation of specific genes in the neural crest cells. 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 extracellular signals and transcription factors are considered will be discussed