Molecular basis of competence for neural induction in the chick embryo

In early chick embryo epiblast, non-competent regions show increased BMP and decreased ERK signalling, and BMP inhibition can restore competence at HH5.

• Why it matters: Neural induction depends on epiblast competence to organizer signals, but three chick embryo regions fail to respond, leaving the molecular basis unclear.
• What they did: Molecular profiling and temporal dynamics after organizer exposure compared outer anterior and posterior area opaca at HH3+-4- and inner anterior area opaca at HH5 versus competent anterior inner area opaca at HH3+-4-. BMP inhibition restored competence to HH5 epiblast, while BMP inhibition plus ERK stimulation with FGF8 conferred competence to the outer area opaca.
• The result: These findings link spatiotemporal competence for neural induction to extracellular BMP and ERK signalling, while posterior epiblast competence could not be induced by these manipulations.