Banded hedgehog and Gli intracellular factors control Xenopus neural crest specification

TRISTÁN H. AGÜERO; GUILLERMO VEGA LÓPEZ; SARA S. SÁNCHEZ; MANUEL J. AYBAR

Ann Arbor, Michigan, USA

Congreso; 65th Annual Meeting of the Society for Developmental Biology; 2006

Society for Developmental Biology

Secreted morphogens of the Hedgehog (Hh) family in Xenopus are sonic hedgehog, cephalic hedgehog and banded hedgehog. They regulate a wide range of developmental processes such as nervous system and limb patterning. Members of the Hh family bind to the transmembrane receptor Patched (Ptc) resulting in the derepression of the protein Smothened (Smo) that regulates the activity of Gli family transcription factors. In this work we revised the expression of banded hedgehog (bhh) and of the components of the intracelular signaling cascade during early development of Xenopus laevis embryos. The double in situ hybridization analysis showed that bhh is expressed during neurulation stages at the lateral border of neural plate in territories that overlap with the expression of Gli transcription factors and neural crest markers. In order to evaluate the participation of bhh pathway in neural crest development, we carried out gain-of and loss-of function approaches by the directed microinjection of bhh mRNA and its dominant negative. Results showed that the overexpression of bhh leads to an increased expression of neural crest markers (Slug, Snail, FoxD3) and Gli transcription factors. On the other hand, the dominant negative construct of bhh and a specific morpholino oligonucleotide reduced the expression of neural crest markers, indicating that bhh signaling is required for neural crest specification. Additionally, the overexpression of Gli3 produced an expansion in neural crest territory mimicking the effect produced by bhh gain of function. Our results show that bhh signaling and Gli transcription factors are participating in the early neural crest development.