Targets of Pax3 and Zic1 in neural crest and cranial placode progenitors

The transcription factors Pax3 and Zic1 are among the earliest genes activated at the neural plate border. Pax3 and Zic1 in combination promote neural crest fate, while Zic1 alone regulate cranial placode progenitor formation. We used microarrays to identify the global repertoire of genes activated by these facors individually or in combination to gain insights into the molecular mechanisms underlying cell fate decision at the neural plate border. Xenopus laevis embryos were injected at the 2-cell stage with mRNA encoding Pax3GR and Zic1GR , the hormone-inducible version of Pax3 and Zic1, alone or in combination. At the blastula stage (stage 9), animal cap explants were dissected and cultured for 8 hours in the presence of dexamethasone. A glucocorticoid receptor (GR) mRNA was also injected as negative control.