Xtwist and Sox-10: two key genes during neural crest development in Xenopus laevis

HONORÉ S. M.; AYBAR M. J.; SANCHEZ S. S.

Valle Nevado

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

Latinamerican Society of Developmental Biology

Neural crest cells arise from the dorsal neural tube and migrate over precise pathways to populate multiple organs and tissues in the developing embryo, they differentiate into many cel1 type inc1uding melanocytes, neurons, and glia. Numerous genes participate in the induction and specification of the cells of the neural crest, between which transcription factors stand out. It has been suggested that Xtwist, a transcription factor of the helix-Ioop-helix (HLH) family also carries out a role in the formation of the neural crests of Xenopus laevis. In this work, we analyzed the function of Xtwist gene through the use of inducible chimeras. The results reveal that the overexpression of Xtwist leads to an increase of neural crest markers like Xslug and Sox9, whereas the overexpression of a dominant negative of Xtwist leads to a reduction in the expression of the these markers. No effect on the express ion of the neural plate marker (Sox 2) and epidermis marker (XK81a) was observed. On the other hand, the gene Sox 10, a protein of HMG box family, has been considered essential for the neural crests development in mammals and zebra fish. Mutations of Sox10 in humans have been related to different pathological conditions that include enteric aganglionosis, deafness and lack of pigmentation in the skin. In our laboratory we have cloned and sequenced the complete Sox10 mRNA of Xenopus laevis. The analysis by in situ hybridization indicates that, Sox 10 begins to be expressed in the presumptive ectoderm of the neural crest at the beginnings of neurulation, and that the expression remains during crest migration. Analysis of function experiments indicate that Sox 10 activity is important for the specification of particularly cell lines derived from the neural crest. These results suggest that the genes Twist and Sox 10 play key roles in the: induction of the neural crest and in the specification of their derivatives.