Nodal and churchill1 position the expression of a notch ligand during Xenopus germ layer segregation

FAVAROLO, M. BELÉN; REVINSKI, R. DIEGO; GARAVAGLIA, MATIAS J.; LÓPEZ, SILVIA L.

Life Science Alliance

WILEY-LISS, DIV JOHN WILEY & SONS INC

Lugar: New York; Año: 2022 vol. 5

2575-1077

Background. In vertebrates, Nodal members of the TGFβ superfamily represent the main endomesoderm inducers, whereas Delta/Notch signaling rather controls delimitation between germ layers. In Xenopus, the marginal zone is a transition area where the limits between germ layers are defined during gastrulation. The transcription factor CHURCHILL1 was proposed to set boundaries between endomesoderm and neuroectoderm in avian embryos. Xenopus churchill1 downregulates the pan-mesodermal marker tbxt, but its expression pattern and its influence on the other germ layers and Notch signaling were unknown. In this work, we aimed to study where the Delta/Notch pathway lays in the gene network comprising churchill1 and Nodal signaling during Xenopus germ layer development. Results. Xenopus churchill1 transcripts are present in the presumptive neuroectoderm at mid-blastula transition and persist during gastrulation, favoring neuroectoderm over endomesoderm development and preventing dll1 expression in the neuroectoderm. Nodal signaling prevents dll1 expression in the endoderm but induces it in the presumptive mesoderm, from where it activates Notch1/hes4 in the non-involuting marginal zone. Conclusions. We propose a model integrating Churchill1, Nodal, and Notch pathways in Xenopus germ layer prepatterning and delimitation. Nodal and Churchill1 position Dll1/Notch1/Hes4 domains in the marginal zone, ensuring the delimitation between mesoderm and neuroectoderm.