Specification of an anterior neuroectoderm patterning by Frizzled8a-mediated Wnt8b signalling during late gastrulation in zebrafish.
Wnts have been shown to provide a posteriorizing signal that has to be repressed in the anterior neuroectoderm for normal anteroposterior (AP) patterning. We have previously identified a zebrafish frizzled8a (fz8a) gene expressed in the presumptive anterior neuroectoderm as well as prechordal plate at the late gastrula stage. We have investigated the role of Fz8a-mediated Wnt8b signalling in anterior brain patterning in zebrafish. We show that in zebrafish embryos: (1) Wnt signalling has at least two different stage-specific posteriorizing activities in the anterior neuroectoderm, one before mid-gastrulation and the other at late gastrulation; (2) Fz8a plays an important role in mediating anterior brain patterning; (3) Wnt8b and Fz8a can functionally interact to transmit posteriorizing signals that determine the fate of the posterior diencephalon and midbrain in late gastrula embryos; and (4) Wnt8b can suppress fz8a expression in the anterior neuroectoderm and potentially affect the level and/or range of Wnt signalling. In conclusion, we suggest that a gradient of Fz8a-mediated Wnt8b signalling may play crucial role in patterning the posterior diencephalon and midbrain regions in the late gastrula.
Kim
Seok-Hyung
SH
Department of Genetic Engineering, Kyungpook National University, Daegu 702-701, Korea.
Shin
Jimann
J
Park
Hae-Chul
HC
Yeo
Sang-Yeob
SY
Hong
Sung-Kook
SK
Han
Sangtae
S
Rhee
Myungchull
M
Kim
Cheol-Hee
CH
Chitnis
Ajay B
AB
Huh
Tae-Lin
TL
D000818:Animals; D019521:Body Patterning / Q000502:physiology*; D001921:Brain / Q000196:embryology*; D004475:Ectoderm; D005123:Eye / Q000196:embryology; D005775:Gastrula / Q000502:physiology; D015870:Gene Expression; D018390:Gene Targeting; D005807:Genes, Overlapping; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D051153:Wnt Proteins; D029867:Xenopus Proteins; D015027:Zebrafish / Q000196:embryology / Q000235:genetics; D029961:Zebrafish Proteins
C113865:FZD8 protein, Xenopus; D011506:Proteins; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; D051153:Wnt Proteins; D029867:Xenopus Proteins; D029961:Zebrafish Proteins; C094522:wnt8b protein, zebrafish