Int. J. Dev. Biol. 57: 779 - 786 (2013)

https://doi.org/10.1387/ijdb.130161tm

Vol 57, Issue 9-10

Xnr3 affects brain patterning via cell migration in the neural-epidermal tissue boundary during early Xenopus embryogenesis

Open Access | Developmental Expression Pattern | Published: 28 June 2013

Mariko Morita¹, Satoshi Yamashita¹, Shinya Matsukawa¹, Yoshikazu Haramoto², Shuji Takahashi³, Makoto Asashima^1,2 and Tatsuo Michiue*^,1

¹Department of Life Sciences, Graduate School of Arts and Sciences, the University of Tokyo, Tokyo, Japan, ²Research Center for Stem Cell Engineering, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan and ³Komaba Organization for Educational Excellence, Graduate School of Arts and Sciences, the University of Tokyo, Tokyo, Japan.

Abstract

Neural induction and anteroposterior neural patterning occur simultaneously during Xenopus gastrulation by the inhibition of BMP and Wnt signaling, respectively. However, other processes might be necessary for determining the neural-epidermal boundary. Xenopus nodal-related-3 (Xnr3) is expressed in dorsal blastula and plays a role in neural formation. In this study, we analyzed how Xnr3 affects neural patterning to identify novel mechanisms of neural-epidermal-boundary determination. In situ hybridization revealed that ventro-animal injection with Xnr3 shifted the lateral krox20 expression domain anteriorly and reduced Otx2 expression. The mature region of Xnr3 is necessary for these effects to occur, and the pro-region accelerated them. Phalloidin labeling revealed that cells around the neural-epidermal boundary lost their slender shape following Xnr3 injection. Moreover, we analyzed the cell migration of ectodermal cells and found specific Xnr3-induced effects at the neural-epidermal boundary. These findings together suggested that Xnr3 affects anterior ectoderm migration around the neural-epidermal boundary to induce a specific neural pattern abnormality. Change of the shape of surrounding ectodermal cells and the specific migratory pattern might therefore reflect the novel mechanism of neural-epidermal boundary.

Keywords

Xenopus, Xnr3, neural-epidermal boundary, ectoderm, neural patterning, cell migration