Cooperative Wnt-Nodal Signals Regulate the Patterning of Anterior Neuroectoderm.
When early canonical Wnt is experimentally inhibited, sea urchin embryos embody the concept of a Default Model in vivo because most of the ectodermal cell fates are specified as anterior neuroectoderm. Using this model, we describe here how the combination of orthogonally functioning anteroposterior Wnt and dorsoventral Nodal signals and their targeting transcription factors, FoxQ2 and Homeobrain, regulates the precise patterning of normal neuroectoderm, of which serotonergic neurons are differentiated only at the dorsal/lateral edge. Loss-of-function experiments revealed that ventral Nodal is required for suppressing the serotonergic neural fate in the ventral side of the neuroectoderm through the maintenance of foxQ2 and the repression of homeobrain expression. In addition, non-canonical Wnt suppressed homeobrain in the anterior end of the neuroectoderm, where serotonergic neurons are not differentiated. Canonical Wnt, however, suppresses foxQ2 to promote neural differentiation. Therefore, the three-dimensionally complex patterning of the neuroectoderm is created by cooperative signals, which are essential for the formation of primary and secondary body axes during embryogenesis.
Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan.
Junko
J
Yaguchi
Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan.
Noriyo
N
Takeda
Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan.
Kazuo
K
Inaba
Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan.
Shunsuke
S
Yaguchi
D000818:Animals; D019521:Body Patterning / Q000235:genetics / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000196:embryology*; D051858:Forkhead Transcription Factors / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D047330:Hemicentrotus / Q000196:embryology*; D018398:Homeodomain Proteins / Q000378:metabolism; D054258:Neural Plate / Q000196:embryology*; D055457:Nodal Protein / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000378:metabolism; D051153:Wnt Proteins / Q000378:metabolism*
D051858:Forkhead Transcription Factors; D018398:Homeodomain Proteins; D055457:Nodal Protein; D016212:Transforming Growth Factor beta; D051153:Wnt Proteins