The Notch-target gene hairy2a impedes the involution of notocordal cells by promoting floor plate in Xenopus laevis embryos

SILVIA L. LÓPEZ, MARÍA V. ROSATO SIRI, PAULA G. FRANCO, ALEJANDRA R. PAGANELLI AND ANDRÉS E. CARRASCO

DEVELOPMENT

The Company of Biologist

Año: 2005 vol. 132 p. 1035 - 1046

0950-1991

We have previously shown that the early Xenopus organiser contains cells equally potent to give rise to notochord or floor plate, and that Notch signalling triggers a binary decision, favouring the floor plate fate at the expense of the notochord. Now, we present evidence that Delta1 is the ligand that triggers the binary switch, which is executed through the Notch-mediated activation of hairy2a in the surrounding cells within the organiser, impeding their involution through the blastopore and promoting their incorporation into the hairy2a+ notoplate precursors (future floor-plate cells) in the dorsal non-involuting marginal zone. Key words: Delta, Notch, Hairy2a, Floor plate, Notochord, Xenopus laevis