title: Xnr3 affects brain patterning via cell migration in the neural-epidermal tissue boundary during early Xenopus embryogenesis.
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.
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, the University of Tokyo, Tokyo, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Morita
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamashita
authors.forename: Shinya
authors.initials: S
authors.lastname: Matsukawa
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Haramoto
authors.forename: Shuji
authors.initials: S
authors.lastname: Takahashi
authors.forename: Makoto
authors.initials: M
authors.lastname: Asashima
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Michiue
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000235:genetics*; D001921:Brain / Q000196:embryology*; D002465:Cell Movement / Q000235:genetics; D051767:Early Growth Response Protein 2 / Q000096:biosynthesis; D004475:Ectoderm / Q000196:embryology; D004625:Embryo, Nonmammalian / Q000378:metabolism; D004627:Embryonic Induction / Q000235:genetics; D004817:Epidermis / Q000196:embryology*; D005136:Eye Proteins; D018507:Gene Expression Regulation, Developmental; D055786:Gene Knockout Techniques; D018398:Homeodomain Proteins / Q000096:biosynthesis; D060172:Morpholinos; D054258:Neural Plate / Q000166:cytology; D054261:Neurulation / Q000235:genetics*; D051857:Otx Transcription Factors / Q000096:biosynthesis; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D029867:Xenopus Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D014982:Xenopus laevis
chemical_list: D051767:Early Growth Response Protein 2; D005136:Eye Proteins; D018398:Homeodomain Proteins; D060172:Morpholinos; D051857:Otx Transcription Factors; C497661:Otx2 protein, Xenopus; C524416:Rax protein, Xenopus; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins; C094620:nodal3.1 protein, Xenopus