Limits...
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.

Show MeSH
Increased β-catenin protein and boz expression in Wnt-5/ppt mutant embryos. Immunolocalization of β-catenin protein in sphere stage embryos. A panel from a confocal series collected with a 20× objective from (A) wild-type and (B) maternally depleted ppt embryos. White dots identify domains of nuclear β-catenin around the circumference of the embryos in an animal pole orientation. Additional confocal images were collected from the same embryos with a 63× objective. Representative β-catenin–positive nuclei noted by arrowheads with one B-catenin–positive nucleus in (C) wild-type and at least seven in (D) maternally depleted ppt embryo.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2172822&req=5

fig5: Increased β-catenin protein and boz expression in Wnt-5/ppt mutant embryos. Immunolocalization of β-catenin protein in sphere stage embryos. A panel from a confocal series collected with a 20× objective from (A) wild-type and (B) maternally depleted ppt embryos. White dots identify domains of nuclear β-catenin around the circumference of the embryos in an animal pole orientation. Additional confocal images were collected from the same embryos with a 63× objective. Representative β-catenin–positive nuclei noted by arrowheads with one B-catenin–positive nucleus in (C) wild-type and at least seven in (D) maternally depleted ppt embryo.

Mentions: One mechanism leading to the dorsalization phenotypes described in the previous paragraph is activation of the canonical Wnt path leading to accumulation of β-catenin protein. Although there is no evidence for a maternal canonical Wnt ligand in zebrafish, there is nuclear accumulation of β-catenin protein on the future dorsal side (Schneider et al., 1996). To determine if there is a change at the level of β-catenin, embryos are analyzed for β-catenin protein distribution. In wild-type embryos, we typically observe nuclear β-catenin spanning ∼20% the circumference of the embryo when observed from the animal pole. Fig. 5 A represents one frame of a confocal series at lower magnification with the regions of nuclear β-catenin localization (dots) confirmed at higher magnification. A representative frame from images collected around the circumference of a wild-type embryo at higher magnification is shown in Fig. 5 C with an arrowhead marking a cell with nuclear β-catenin. In wild type, we observe an average of 11 β-catenin-positive nuclei/embryo, (n = 10 embryos). In contrast, β-catenin-positive nuclei in embryos from ppt−/− females span >50% the embryo circumference, in some embryos, the domains are opposite the putative endogenous dorsal domain (Fig. 5 B, dots). Embryos from ppt−/− females demonstrate a dramatically higher number of cells with nuclear β-catenin (Average of 48 nuclei/embryo, n = 10 embryos) with a noticeable increase in the overall level of protein (Fig. 5 D, arrows denoting a few of the cells with nuclear β-catenin). The individual panels of wild type at higher magnification typically have 1–2 nuclei/frame in the dorsal domain, whereas ppt panels can have upwards of 6–10 nuclei/frame.


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)

Increased β-catenin protein and boz expression in Wnt-5/ppt mutant embryos. Immunolocalization of β-catenin protein in sphere stage embryos. A panel from a confocal series collected with a 20× objective from (A) wild-type and (B) maternally depleted ppt embryos. White dots identify domains of nuclear β-catenin around the circumference of the embryos in an animal pole orientation. Additional confocal images were collected from the same embryos with a 63× objective. Representative β-catenin–positive nuclei noted by arrowheads with one B-catenin–positive nucleus in (C) wild-type and at least seven in (D) maternally depleted ppt embryo.
© Copyright Policy
Related In: Results  -  Collection

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

fig5: Increased β-catenin protein and boz expression in Wnt-5/ppt mutant embryos. Immunolocalization of β-catenin protein in sphere stage embryos. A panel from a confocal series collected with a 20× objective from (A) wild-type and (B) maternally depleted ppt embryos. White dots identify domains of nuclear β-catenin around the circumference of the embryos in an animal pole orientation. Additional confocal images were collected from the same embryos with a 63× objective. Representative β-catenin–positive nuclei noted by arrowheads with one B-catenin–positive nucleus in (C) wild-type and at least seven in (D) maternally depleted ppt embryo.
Mentions: One mechanism leading to the dorsalization phenotypes described in the previous paragraph is activation of the canonical Wnt path leading to accumulation of β-catenin protein. Although there is no evidence for a maternal canonical Wnt ligand in zebrafish, there is nuclear accumulation of β-catenin protein on the future dorsal side (Schneider et al., 1996). To determine if there is a change at the level of β-catenin, embryos are analyzed for β-catenin protein distribution. In wild-type embryos, we typically observe nuclear β-catenin spanning ∼20% the circumference of the embryo when observed from the animal pole. Fig. 5 A represents one frame of a confocal series at lower magnification with the regions of nuclear β-catenin localization (dots) confirmed at higher magnification. A representative frame from images collected around the circumference of a wild-type embryo at higher magnification is shown in Fig. 5 C with an arrowhead marking a cell with nuclear β-catenin. In wild type, we observe an average of 11 β-catenin-positive nuclei/embryo, (n = 10 embryos). In contrast, β-catenin-positive nuclei in embryos from ppt−/− females span >50% the embryo circumference, in some embryos, the domains are opposite the putative endogenous dorsal domain (Fig. 5 B, dots). Embryos from ppt−/− females demonstrate a dramatically higher number of cells with nuclear β-catenin (Average of 48 nuclei/embryo, n = 10 embryos) with a noticeable increase in the overall level of protein (Fig. 5 D, arrows denoting a few of the cells with nuclear β-catenin). The individual panels of wild type at higher magnification typically have 1–2 nuclei/frame in the dorsal domain, whereas ppt panels can have upwards of 6–10 nuclei/frame.

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