Ets-1 confers cranial features on neural crest delamination.

(A) Normal delamination of cranial NCCs. Premigratory and migratory NCCs expressing ets-1 are in purple. (B) Normal delamination of trunk NCCs. Premigratory and migratory NCCs are in yellow. (C) Consequences of ets-1 electroporation in trunk neural tube at dorsal and at intermediate to ventral levels. Ets-1 electroporated cells are coloured in green. (D) Cell movements induced by ets-1 expression. Proliferating cells are in grey, non-proliferating cells are in blue. Ets-1 electroporated cells are dotted in green. Cell-cell junctions involving N-cadherin are represented by black centers. Nuclei in S-phase are colored in black. Basal lamina is represented by twisted red line. Cranial NCCs express ets-1 and massively delaminate independently of G1/S transition (A) whereas trunk NCCs do not express ets-1 and delaminate progressively as a cell population subjected to successful G1/S transition (B). When ets-1 expression is forced in the dorsal part of trunk neural tube, trunk NCCs delamination is greatly enhanced and cells emigrate as multilayered streams (C, green cells). Moreover, they lose their subjection to cell cycle progression indicating that ets-1 converts trunk delamination into cranial-like emigration (C). Ectopic ets-1 expression in ventral part of the neuroepithelium leads to massive cell movements without affecting cell proliferation or differentiation. Electroporated cells are accumulated close to the basal side of the neural tube and the basal lamina is degraded (C, D). These events are sufficient to initiate delamination. However, other factors such as snail-2 are required to perform full delamination and promote EMT and cell migration. M, cell in mitosis.