Analysis of Hairy gene family in Xenopus neural crest development

GUILLERMO VEGA LÓPEZ; CRISTINA ZAMORANO; MANUEL J. AYBAR; SARA S. SÁNCHEZ

Guarujá, Brasil

Congreso; Second International Meeting of the Latinamerican Society of Developmental Biology; 2005

It has been demonstrated that the yuxtacrine cell signaling pathway Notch/Delta is involved in the induction of neural crest in different vertebrate animal models. The genes of the Hairy family, encode transcription factors containing a bHLH DNA binding domain that are direct targets of Notch/Delta signaling in vertebrates and invertebrates. In this work, a comparative analysis of the spatio-temporal expression patterns of Xenopus Hairy genes (Hairy1, Hairy2a and Hairy2b) has been performed by single and double wholemount in situ hybridization. Our results showed that Hairy1 is expressed in a narrow line at the border of neural plate and in the epidermis-neural crest boundary from late gastrula stage to mid-neurula stage. Hairy2a and Hairy2b are both expressed in the border of the neural plate in the prospective neural crest territory. In contrast to Hairy2a, Hairy2b showed only a minor expression in the anterior neural fold. At later stages, Hairy2a and Hairy2b are expressed in migratory cephalic neural crest. In order to analyze the role of Hairy genes during neural crest induction by conditional gain- and loss-of-function, we have prepared chimeric inducible proteins and their dominant negatives by fusing coding sequences to the ligand binding domain of human glucocorticoid receptor. The overexpression of chimeric inducible proteins by microinjection of in vitro transcribed mRNA in segmenting embryos activated at late gastrula stage showed that Hairy genes are involved in neural crest induction. Our results provide detailed comparative information about the expression patterns of Hairy genes and support a role for them during neural crest development in Xenopus embryos.