ZFIN ID: ZDB-PUB-030408-4
Analysis of Wnt8 for neural posteriorizing factor by identifying Frizzled 8c and Frizzled 9 as functional receptors for Wnt8
Momoi, A., Yoda, H., Steinbeisser, H., Fagotto, F., Kondoh, H., Kudo, A., Driever, W., and Furutani-Seiki, M.
Date: 2003
Source: Mechanisms of Development 120(4): 477-489 (Journal)
Registered Authors: Driever, Wolfgang, Furutani-Seiki, Makoto, Kondoh, Hisato
Keywords: none
MeSH Terms: Amino Acid Sequence; Animals; Blotting, Northern; Cell Nucleus/metabolism; Cytoskeletal Proteins/metabolism (all 31) expand
PubMed: 12676325 Full text @ Mech. Dev.
ABSTRACT
The dorsal ectoderm of vertebrate gastrula is first specified into anterior fate by an activation signal and posteriorized by a graded transforming signal, leading to the formation of forebrain, midbrain, hindbrain and spinal cord along the anteroposterior (A-P) axis. Transplanted non-axial mesoderm rather than axial mesoderm has an ability to transform prospective anterior neural tissue into more posterior fates in zebrafish. Wnt8 is a secreted factor that is expressed in non-axial mesoderm. To investigate whether Wnt8 is the neural posteriorizing factor that acts upon neuroectoderm, we first assigned Frizzled 8c and Frizzled 9 to be functional receptors for Wnt8. We then, transplanted non-axial mesoderm into the embryos in which Wnt8 signaling is cell-autonomously blocked by the dominant-negative form of Wnt8 receptors. Non-axial mesodermal transplants in embryos in which Wnt8 signaling is cell-autonomously blocked induced the posterior neural markers as efficiently as in wild-type embryos, suggesting that Wnt8 signaling is not required in neuroectoderm for posteriorization by non-axial mesoderm. Furthermore, Wnt8 signaling, detected by nuclear localization of beta-catenin, was not activated in the posterior neuroectoderm but confined in marginal non-axial mesoderm. Finally, ubiquitous over-expression of Wnt8 does not expand neural ectoderm of posterior character in the absence of mesoderm or Nodal-dependent co-factors. We thus conclude that other factors from non-axial mesoderm may be required for patterning neuroectoderm along the A-P axis.
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