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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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Increased boz expression in Wnt-5/ppt mutant embryos. Whole mount in situ hybridization with boz; animal pole view of (A) wild-type and (B-D) mz-ppt embryos; dorsal view of (E) wild-type and (F) (ppt−/−;slb−/−) embryos. The arrows mark the lateral extent of the boz expression domain and plus marks highlight ectopic domains.
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fig6: Increased boz expression in Wnt-5/ppt mutant embryos. Whole mount in situ hybridization with boz; animal pole view of (A) wild-type and (B-D) mz-ppt embryos; dorsal view of (E) wild-type and (F) (ppt−/−;slb−/−) embryos. The arrows mark the lateral extent of the boz expression domain and plus marks highlight ectopic domains.

Mentions: To analyze increased Wnt/β-catenin activity at the molecular level, we monitored expression of a downstream target, the homeodomain protein bozozok (Fekany et al., 1999). boz zygotic expression initiates at the dorsal blastoderm and dorsal YSL indicating the zebrafish organizer at 4 hpf (Fig. 6 A). 59% of embryos from ppt−/− females have expanded and/or ectopic boz expression (n = 147; Fig. 6, B–D). The ppt−/− embryos in Fig. 6 (B and C) display lateral expansion (arrowheads) of the boz expression domain as well as an increased number of boz-positive cells. Additionally ectopic domain of boz expression can be observed as a group of cells (Fig. 6 B) or as individual boz-positive cells (Fig. 6 D). Because a milder ppt allele (pptta89 ) has redundant functions with slb in anterior cell movements (Kilian et al., 2003), we wanted to confirm genetic interaction between pptti265 and slbtz216 or potential functional redundancy between the Wnt-5 and -11 products in earlier embryonic stages. We evaluated boz distribution in embryos collected from a cross between doubly heterozygous pptti265 and slbtz216 parents. In the doubly homozygous pptti265; slbtz216 mutant embryos, we observed an increase in the boz expression domain with a larger number of strongly expressing boz-positive cells forming a dark trapezoid shape (14%, n = 96; Fig. 6 F) compared with the linear pattern of weakly expressing boz-positive cells in wild-type (Fig. 6 E) and single mutant pptti265 or slbtz216 embryos (0%, n = 146). The mild increase in the boz expression domain suggests that there may be a zygotic contribution from this class of Wnts to maintain or refine, in part, the maternally established D-V boundaries.


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 boz expression in Wnt-5/ppt mutant embryos. Whole mount in situ hybridization with boz; animal pole view of (A) wild-type and (B-D) mz-ppt embryos; dorsal view of (E) wild-type and (F) (ppt−/−;slb−/−) embryos. The arrows mark the lateral extent of the boz expression domain and plus marks highlight ectopic domains.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2172822&req=5

fig6: Increased boz expression in Wnt-5/ppt mutant embryos. Whole mount in situ hybridization with boz; animal pole view of (A) wild-type and (B-D) mz-ppt embryos; dorsal view of (E) wild-type and (F) (ppt−/−;slb−/−) embryos. The arrows mark the lateral extent of the boz expression domain and plus marks highlight ectopic domains.
Mentions: To analyze increased Wnt/β-catenin activity at the molecular level, we monitored expression of a downstream target, the homeodomain protein bozozok (Fekany et al., 1999). boz zygotic expression initiates at the dorsal blastoderm and dorsal YSL indicating the zebrafish organizer at 4 hpf (Fig. 6 A). 59% of embryos from ppt−/− females have expanded and/or ectopic boz expression (n = 147; Fig. 6, B–D). The ppt−/− embryos in Fig. 6 (B and C) display lateral expansion (arrowheads) of the boz expression domain as well as an increased number of boz-positive cells. Additionally ectopic domain of boz expression can be observed as a group of cells (Fig. 6 B) or as individual boz-positive cells (Fig. 6 D). Because a milder ppt allele (pptta89 ) has redundant functions with slb in anterior cell movements (Kilian et al., 2003), we wanted to confirm genetic interaction between pptti265 and slbtz216 or potential functional redundancy between the Wnt-5 and -11 products in earlier embryonic stages. We evaluated boz distribution in embryos collected from a cross between doubly heterozygous pptti265 and slbtz216 parents. In the doubly homozygous pptti265; slbtz216 mutant embryos, we observed an increase in the boz expression domain with a larger number of strongly expressing boz-positive cells forming a dark trapezoid shape (14%, n = 96; Fig. 6 F) compared with the linear pattern of weakly expressing boz-positive cells in wild-type (Fig. 6 E) and single mutant pptti265 or slbtz216 embryos (0%, n = 146). The mild increase in the boz expression domain suggests that there may be a zygotic contribution from this class of Wnts to maintain or refine, in part, the maternally established D-V boundaries.

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