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Wnt-5/pipetail functions in vertebrate axis formation as a negative regulator of Wnt/beta-catenin activity.

Westfall TA, Brimeyer R, Twedt J, Gladon J, Olberding A, Furutani-Seiki M, Slusarski DC - J. Cell Biol. (2003)

Bottom Line: We describe genetic interaction between two Wnt/Ca2+ members, Wnt-5 (pipetail) and Wnt-11 (silberblick), and a reduction of Ca2+ release in Wnt-5/pipetail.The dorsalized phenotypes result from increased beta-catenin accumulation and activation of downstream genes.The Wnt-5 loss-of-function defect is consistent with Ca2+ modulation having an antagonistic interaction with Wnt/beta-catenin signaling.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University of Iowa, Iowa City, IA 52242, USA.

ABSTRACT
We provide genetic evidence defining a role for noncanonical Wnt function in vertebrate axis formation. In zebrafish, misexpression of Wnt-4, -5, and -11 stimulates calcium (Ca2+) release, defining the Wnt/Ca2+ class. We describe genetic interaction between two Wnt/Ca2+ members, Wnt-5 (pipetail) and Wnt-11 (silberblick), and a reduction of Ca2+ release in Wnt-5/pipetail. Embryos genetically depleted of both maternal and zygotic Wnt-5 product exhibit cell movement defects as well as hyperdorsalization and axis-duplication phenotypes. The dorsalized phenotypes result from increased beta-catenin accumulation and activation of downstream genes. The Wnt-5 loss-of-function defect is consistent with Ca2+ modulation having an antagonistic interaction with Wnt/beta-catenin signaling.

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Ca2+ release dynamics in zebrafish embryos expressing Wnts and in Wnt-5/ppt mutants. Non-canonical Wnt members stimulate Ca2+ release in zebrafish and these changes were monitored with Fura-2 in live embryos. The representative embryo shown is a two-dimensional topographic image of the location of all the Ca2+ fluxes that occurred during the time course (50 min). Surface plots of Ca2+ release activity in embryos mis-expressing (A) Wnt-11 and (B) Wnt-8 RNA. Ca2+ release profile of endogenous activity in (C) heterozygous (ppt+/−) and (D) mutant (ppt−/−) embryos from the same clutch. Height and color of peaks indicate the number of Ca2+ fluxes observed over the course of the experiment with the embryos oriented in a lateral position. The color bar indicates the pseudocolor representation of the number of transients from low (purple, 1) to high (red, 40).
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fig1: Ca2+ release dynamics in zebrafish embryos expressing Wnts and in Wnt-5/ppt mutants. Non-canonical Wnt members stimulate Ca2+ release in zebrafish and these changes were monitored with Fura-2 in live embryos. The representative embryo shown is a two-dimensional topographic image of the location of all the Ca2+ fluxes that occurred during the time course (50 min). Surface plots of Ca2+ release activity in embryos mis-expressing (A) Wnt-11 and (B) Wnt-8 RNA. Ca2+ release profile of endogenous activity in (C) heterozygous (ppt+/−) and (D) mutant (ppt−/−) embryos from the same clutch. Height and color of peaks indicate the number of Ca2+ fluxes observed over the course of the experiment with the embryos oriented in a lateral position. The color bar indicates the pseudocolor representation of the number of transients from low (purple, 1) to high (red, 40).

Mentions: Zebrafish embryos overexpressing Wnt-5A produce developmental defects similar to those induced by agents that stimulate phosphatidylinositol cycle activity (Slusarski et al., 1997b). Stimulation of the phosphatidylinositol cycle leads to intracellular Ca2+ release. Using in vivo image analysis in zebrafish, we demonstrated that Xenopus Wnt-5A overexpression increases Ca2+ release frequency twofold over endogenous levels (Slusarski et al., 1997b). We now ask if the zebrafish Wnt genes modulate Ca2+ release. Zebrafish embryos microinjected with a Ca2+-sensitive dye along with the respective RNA are subjected to image analysis. Overexpression of zebrafish noncanonical Wnts (Wnt-4, -5, and -11) is sufficient to increase the frequency of Ca2+ release at least twofold over endogenous levels (zWnt-11; Fig. 1 A). Conversely, the canonical Wnt-8 does not change the levels of Ca2+ release relative to endogenous levels (Fig. 1 B). The Wnt-8 RNA is translated into a functional product in this assay as it induced dorsalization. The differential ability of the Wnt classes to modulate Ca2+ release is consistent with our earlier studies with Wnts and Frizzleds from other species (Slusarski et al., 1997a,b; Ahumada et al., 2002). Given that subtle differences in the amplitude and/or frequency of Ca2+ release can have profound effects on cell behavior (Berridge et al., 1998), we next characterized the impact Wnt-5-stimulated Ca2+ release on embryonic patterning.


Wnt-5/pipetail functions in vertebrate axis formation as a negative regulator of Wnt/beta-catenin activity.

Westfall TA, Brimeyer R, Twedt J, Gladon J, Olberding A, Furutani-Seiki M, Slusarski DC - J. Cell Biol. (2003)

Ca2+ release dynamics in zebrafish embryos expressing Wnts and in Wnt-5/ppt mutants. Non-canonical Wnt members stimulate Ca2+ release in zebrafish and these changes were monitored with Fura-2 in live embryos. The representative embryo shown is a two-dimensional topographic image of the location of all the Ca2+ fluxes that occurred during the time course (50 min). Surface plots of Ca2+ release activity in embryos mis-expressing (A) Wnt-11 and (B) Wnt-8 RNA. Ca2+ release profile of endogenous activity in (C) heterozygous (ppt+/−) and (D) mutant (ppt−/−) embryos from the same clutch. Height and color of peaks indicate the number of Ca2+ fluxes observed over the course of the experiment with the embryos oriented in a lateral position. The color bar indicates the pseudocolor representation of the number of transients from low (purple, 1) to high (red, 40).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172822&req=5

fig1: Ca2+ release dynamics in zebrafish embryos expressing Wnts and in Wnt-5/ppt mutants. Non-canonical Wnt members stimulate Ca2+ release in zebrafish and these changes were monitored with Fura-2 in live embryos. The representative embryo shown is a two-dimensional topographic image of the location of all the Ca2+ fluxes that occurred during the time course (50 min). Surface plots of Ca2+ release activity in embryos mis-expressing (A) Wnt-11 and (B) Wnt-8 RNA. Ca2+ release profile of endogenous activity in (C) heterozygous (ppt+/−) and (D) mutant (ppt−/−) embryos from the same clutch. Height and color of peaks indicate the number of Ca2+ fluxes observed over the course of the experiment with the embryos oriented in a lateral position. The color bar indicates the pseudocolor representation of the number of transients from low (purple, 1) to high (red, 40).
Mentions: Zebrafish embryos overexpressing Wnt-5A produce developmental defects similar to those induced by agents that stimulate phosphatidylinositol cycle activity (Slusarski et al., 1997b). Stimulation of the phosphatidylinositol cycle leads to intracellular Ca2+ release. Using in vivo image analysis in zebrafish, we demonstrated that Xenopus Wnt-5A overexpression increases Ca2+ release frequency twofold over endogenous levels (Slusarski et al., 1997b). We now ask if the zebrafish Wnt genes modulate Ca2+ release. Zebrafish embryos microinjected with a Ca2+-sensitive dye along with the respective RNA are subjected to image analysis. Overexpression of zebrafish noncanonical Wnts (Wnt-4, -5, and -11) is sufficient to increase the frequency of Ca2+ release at least twofold over endogenous levels (zWnt-11; Fig. 1 A). Conversely, the canonical Wnt-8 does not change the levels of Ca2+ release relative to endogenous levels (Fig. 1 B). The Wnt-8 RNA is translated into a functional product in this assay as it induced dorsalization. The differential ability of the Wnt classes to modulate Ca2+ release is consistent with our earlier studies with Wnts and Frizzleds from other species (Slusarski et al., 1997a,b; Ahumada et al., 2002). Given that subtle differences in the amplitude and/or frequency of Ca2+ release can have profound effects on cell behavior (Berridge et al., 1998), we next characterized the impact Wnt-5-stimulated Ca2+ release on embryonic patterning.

Bottom Line: We describe genetic interaction between two Wnt/Ca2+ members, Wnt-5 (pipetail) and Wnt-11 (silberblick), and a reduction of Ca2+ release in Wnt-5/pipetail.The dorsalized phenotypes result from increased beta-catenin accumulation and activation of downstream genes.The Wnt-5 loss-of-function defect is consistent with Ca2+ modulation having an antagonistic interaction with Wnt/beta-catenin signaling.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University of Iowa, Iowa City, IA 52242, USA.

ABSTRACT
We provide genetic evidence defining a role for noncanonical Wnt function in vertebrate axis formation. In zebrafish, misexpression of Wnt-4, -5, and -11 stimulates calcium (Ca2+) release, defining the Wnt/Ca2+ class. We describe genetic interaction between two Wnt/Ca2+ members, Wnt-5 (pipetail) and Wnt-11 (silberblick), and a reduction of Ca2+ release in Wnt-5/pipetail. Embryos genetically depleted of both maternal and zygotic Wnt-5 product exhibit cell movement defects as well as hyperdorsalization and axis-duplication phenotypes. The dorsalized phenotypes result from increased beta-catenin accumulation and activation of downstream genes. The Wnt-5 loss-of-function defect is consistent with Ca2+ modulation having an antagonistic interaction with Wnt/beta-catenin signaling.

Show MeSH