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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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Phenotypes of Wnt-5/ppt maternal-depleted embryos. Tail and trunk morphology in (A and E) wild-type, (B) zygotic ppt−/−, and embryos collected from ppt−/− females in C, D, F, and G. The embryo in C is an example of what was scored as a severe zygotic ppt-like phenotype with a severely shortened trunk. The phenotypes of embryos in D and F resemble two of the extreme classes of dorsalized mutants, whereas the embryo in G has a partial secondary axis (center, foreground) branching off of the primary axis (left, background). The ectopic axis has a beating heart and otic vesicles, an arrowhead highlighting one otic vesicle. Whole mount in situ analysis of embryos from ppt−/− females. After photographing, genotypes were determined by PCR. mz-ppt represents maternal and zygotic loss of Wnt-5. Lateral view of 36 hpf embryos probed for the heart with Nkx2.5 in (H) wild-type and (I) mz-ppt, the black arrows show the endogenous heart, whereas the ectopic staining is noted with a white arrow. Animal pole view of embryos at 50% epiboly with dorsal to the right and arrowheads marking the lateral extent of the chordin expression domain in (J) wild-type, (K) mz-ppt, and in (L) mz-ppt, the star demarcates an ectopic domain.
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fig4: Phenotypes of Wnt-5/ppt maternal-depleted embryos. Tail and trunk morphology in (A and E) wild-type, (B) zygotic ppt−/−, and embryos collected from ppt−/− females in C, D, F, and G. The embryo in C is an example of what was scored as a severe zygotic ppt-like phenotype with a severely shortened trunk. The phenotypes of embryos in D and F resemble two of the extreme classes of dorsalized mutants, whereas the embryo in G has a partial secondary axis (center, foreground) branching off of the primary axis (left, background). The ectopic axis has a beating heart and otic vesicles, an arrowhead highlighting one otic vesicle. Whole mount in situ analysis of embryos from ppt−/− females. After photographing, genotypes were determined by PCR. mz-ppt represents maternal and zygotic loss of Wnt-5. Lateral view of 36 hpf embryos probed for the heart with Nkx2.5 in (H) wild-type and (I) mz-ppt, the black arrows show the endogenous heart, whereas the ectopic staining is noted with a white arrow. Animal pole view of embryos at 50% epiboly with dorsal to the right and arrowheads marking the lateral extent of the chordin expression domain in (J) wild-type, (K) mz-ppt, and in (L) mz-ppt, the star demarcates an ectopic domain.

Mentions: Consistent with maternal effect mutations, embryos collected from ppt−/− females exhibit phenotypes regardless of the paternal genotype. Embryos from ppt−/− females crossed to heterozygous ppt+/− males fell into two general phenotypic groups. One class, accounting for >50% of the defects, is similar to the tail defects observed in mutant embryos from heterozygous females (Fig. 4 B), however, embryos from ppt−/− females have pointedly more severe defects with extreme shortened axis, undulating notochord and tail defects (Fig. 4 C). This class of phenotypes was scored as ppt-zygotic–like. The other phenotypic group (38%, 193/506) demonstrated dorsalized mutant phenotypes similar to those described in Mullins et al. (1996), as well as axis duplication phenotypes. These include expansion of somites, shortened and twisted tail (piggy-tail–like; Fig. 4 D) and severe curling of the tail over the trunk (snail-house–like; Fig. 4 F) instead of straight extension off of the yolk as in wild-type (Fig. 4, A and E). The ppt−/− embryo in Fig. 4 G has a partial secondary axis with an ectopic pair of otic vesicles associated with a duplicated beating heart. Organ duplication was verified in several maternal-zygotic ppt−/− (mzppt) embryos by whole mount in situ with a cardiac specific probe (Fig. 4 I; Chen and Fishman, 1996). Based on morphology, the hyperdorsalized and duplicated axis defect frequency of 38% is consistent, yet lower than the expected 50% frequency for embryos depleted of both maternal and zygotic product. The lower frequency could be the result of a maternal effect that is not fully penetrant or that we were conservative in scoring a phenotype as dorsalized and instead classified it as a severe ppt-zygotic–like defect. To distinguish between these two possibilities, we employed a more sensitive molecular analysis of dorsal 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)

Phenotypes of Wnt-5/ppt maternal-depleted embryos. Tail and trunk morphology in (A and E) wild-type, (B) zygotic ppt−/−, and embryos collected from ppt−/− females in C, D, F, and G. The embryo in C is an example of what was scored as a severe zygotic ppt-like phenotype with a severely shortened trunk. The phenotypes of embryos in D and F resemble two of the extreme classes of dorsalized mutants, whereas the embryo in G has a partial secondary axis (center, foreground) branching off of the primary axis (left, background). The ectopic axis has a beating heart and otic vesicles, an arrowhead highlighting one otic vesicle. Whole mount in situ analysis of embryos from ppt−/− females. After photographing, genotypes were determined by PCR. mz-ppt represents maternal and zygotic loss of Wnt-5. Lateral view of 36 hpf embryos probed for the heart with Nkx2.5 in (H) wild-type and (I) mz-ppt, the black arrows show the endogenous heart, whereas the ectopic staining is noted with a white arrow. Animal pole view of embryos at 50% epiboly with dorsal to the right and arrowheads marking the lateral extent of the chordin expression domain in (J) wild-type, (K) mz-ppt, and in (L) mz-ppt, the star demarcates an ectopic domain.
© Copyright Policy
Related In: Results  -  Collection

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

fig4: Phenotypes of Wnt-5/ppt maternal-depleted embryos. Tail and trunk morphology in (A and E) wild-type, (B) zygotic ppt−/−, and embryos collected from ppt−/− females in C, D, F, and G. The embryo in C is an example of what was scored as a severe zygotic ppt-like phenotype with a severely shortened trunk. The phenotypes of embryos in D and F resemble two of the extreme classes of dorsalized mutants, whereas the embryo in G has a partial secondary axis (center, foreground) branching off of the primary axis (left, background). The ectopic axis has a beating heart and otic vesicles, an arrowhead highlighting one otic vesicle. Whole mount in situ analysis of embryos from ppt−/− females. After photographing, genotypes were determined by PCR. mz-ppt represents maternal and zygotic loss of Wnt-5. Lateral view of 36 hpf embryos probed for the heart with Nkx2.5 in (H) wild-type and (I) mz-ppt, the black arrows show the endogenous heart, whereas the ectopic staining is noted with a white arrow. Animal pole view of embryos at 50% epiboly with dorsal to the right and arrowheads marking the lateral extent of the chordin expression domain in (J) wild-type, (K) mz-ppt, and in (L) mz-ppt, the star demarcates an ectopic domain.
Mentions: Consistent with maternal effect mutations, embryos collected from ppt−/− females exhibit phenotypes regardless of the paternal genotype. Embryos from ppt−/− females crossed to heterozygous ppt+/− males fell into two general phenotypic groups. One class, accounting for >50% of the defects, is similar to the tail defects observed in mutant embryos from heterozygous females (Fig. 4 B), however, embryos from ppt−/− females have pointedly more severe defects with extreme shortened axis, undulating notochord and tail defects (Fig. 4 C). This class of phenotypes was scored as ppt-zygotic–like. The other phenotypic group (38%, 193/506) demonstrated dorsalized mutant phenotypes similar to those described in Mullins et al. (1996), as well as axis duplication phenotypes. These include expansion of somites, shortened and twisted tail (piggy-tail–like; Fig. 4 D) and severe curling of the tail over the trunk (snail-house–like; Fig. 4 F) instead of straight extension off of the yolk as in wild-type (Fig. 4, A and E). The ppt−/− embryo in Fig. 4 G has a partial secondary axis with an ectopic pair of otic vesicles associated with a duplicated beating heart. Organ duplication was verified in several maternal-zygotic ppt−/− (mzppt) embryos by whole mount in situ with a cardiac specific probe (Fig. 4 I; Chen and Fishman, 1996). Based on morphology, the hyperdorsalized and duplicated axis defect frequency of 38% is consistent, yet lower than the expected 50% frequency for embryos depleted of both maternal and zygotic product. The lower frequency could be the result of a maternal effect that is not fully penetrant or that we were conservative in scoring a phenotype as dorsalized and instead classified it as a severe ppt-zygotic–like defect. To distinguish between these two possibilities, we employed a more sensitive molecular analysis of dorsal 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
Related in: MedlinePlus