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The single Drosophila ZO-1 protein Polychaetoid regulates embryonic morphogenesis in coordination with Canoe/afadin and Enabled.

Choi W, Jung KC, Nelson KS, Bhat MA, Beitel GJ, Peifer M, Fanning AS - Mol. Biol. Cell (2011)

Bottom Line: Pyd loss does not dramatically affect AJ protein localization or initial localization of actin and myosin during dorsal closure.The defects, which include segmental grooves that fail to retract, a disrupted leading edge actin cable, and reduced zippering as leading edges meet, closely resemble defects in canoe zygotic mutants and in embryos lacking the actin regulator Enabled (Ena), suggesting that these proteins act together.Canoe (Cno) and Pyd are required for proper Ena localization during dorsal closure, and strong genetic interactions suggest that Cno, Pyd, and Ena act together in regulating or anchoring the actin cytoskeleton during dorsal closure.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of North Carolina at Chapel Hill, USA.

ABSTRACT
Adherens and tight junctions play key roles in assembling epithelia and maintaining barriers. In cell culture zonula occludens (ZO)-family proteins are important for assembly/maturation of both tight and adherens junctions (AJs). Genetic studies suggest that ZO proteins are important during normal development, but interpretation of mouse and fly studies is limited by genetic redundancy and/or a lack of alleles. We generated alleles of the single Drosophila ZO protein Polychaetoid (Pyd). Most embryos lacking Pyd die with striking defects in morphogenesis of embryonic epithelia including the epidermis, segmental grooves, and tracheal system. Pyd loss does not dramatically affect AJ protein localization or initial localization of actin and myosin during dorsal closure. However, Pyd loss does affect several cell behaviors that drive dorsal closure. The defects, which include segmental grooves that fail to retract, a disrupted leading edge actin cable, and reduced zippering as leading edges meet, closely resemble defects in canoe zygotic mutants and in embryos lacking the actin regulator Enabled (Ena), suggesting that these proteins act together. Canoe (Cno) and Pyd are required for proper Ena localization during dorsal closure, and strong genetic interactions suggest that Cno, Pyd, and Ena act together in regulating or anchoring the actin cytoskeleton during dorsal closure.

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pyd and ena also exhibit strong, dose-sensitive genetic interactions. (A–E) Cuticles of embryos, exhibiting representative phenotypes scored in the different genotypes. (A) Example of normal or nearly normal head skeleton (arrow). (B) Example of moderate to severe defects in the head skeleton (arrow), indicative of defects in head involution. (C) Example of a more severe phenotypic class, exhibiting either a head hole due to complete failure of head involution (arrow; illustrated here), a large dorsal hole, indicating failure of dorsal closure (not shown), or both. (D) Example of an embryo in which head involution failed (top arrow) and there was one or more holes in the dorsal cuticle (bottom arrow). (E) Example of the most severe phenotype, in which the remaining cuticle was fragmented. (F) Percentages of dead embryos in each phenotypic class for different genetic interaction crosses. Note that this actually underestimates the enhancement of the ena phenotype by reduction of Pyd levels, as not all ena zygotic mutant embryos die (19% relative to 25% expected from the cross), whereas essentially all ena zygotic mutants with reduced Pyd die (25% relative to 25% expected). Presumably those ena zygotic mutants that hatch as larvae have an essentially wild-type cuticle phenotype. Scale bar, 75 μm.
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Figure 12: pyd and ena also exhibit strong, dose-sensitive genetic interactions. (A–E) Cuticles of embryos, exhibiting representative phenotypes scored in the different genotypes. (A) Example of normal or nearly normal head skeleton (arrow). (B) Example of moderate to severe defects in the head skeleton (arrow), indicative of defects in head involution. (C) Example of a more severe phenotypic class, exhibiting either a head hole due to complete failure of head involution (arrow; illustrated here), a large dorsal hole, indicating failure of dorsal closure (not shown), or both. (D) Example of an embryo in which head involution failed (top arrow) and there was one or more holes in the dorsal cuticle (bottom arrow). (E) Example of the most severe phenotype, in which the remaining cuticle was fragmented. (F) Percentages of dead embryos in each phenotypic class for different genetic interaction crosses. Note that this actually underestimates the enhancement of the ena phenotype by reduction of Pyd levels, as not all ena zygotic mutant embryos die (19% relative to 25% expected from the cross), whereas essentially all ena zygotic mutants with reduced Pyd die (25% relative to 25% expected). Presumably those ena zygotic mutants that hatch as larvae have an essentially wild-type cuticle phenotype. Scale bar, 75 μm.

Mentions: We next explored whether ena genetically interacts with pyd. As we observed with Cno, reducing Pyd levels (by crossing ena/+;pyd/+ males and females) strongly enhanced the morphogenesis defects of zygotic ena mutants, substantially increasing the frequency of failure of head involution (Figure 12F, bottom four genotypes). This was true for two different pyd alleles, pydB12 and pydex180. In addition, reducing Ena levels also substantially enhanced the severity of the pydMZ phenotype; more than one-third of the mutants now exhibited large holes in the cuticle, suggesting disruption of epithelial integrity (Figure 12F, top two genotypes). The dose-sensitive genetic interactions of ena with both cno and pyd are consistent with those seen with joint reduction of proteins in the same pathway and support the hypothesis that Cno and Pyd work with or through Ena during embryonic morphogenesis.


The single Drosophila ZO-1 protein Polychaetoid regulates embryonic morphogenesis in coordination with Canoe/afadin and Enabled.

Choi W, Jung KC, Nelson KS, Bhat MA, Beitel GJ, Peifer M, Fanning AS - Mol. Biol. Cell (2011)

pyd and ena also exhibit strong, dose-sensitive genetic interactions. (A–E) Cuticles of embryos, exhibiting representative phenotypes scored in the different genotypes. (A) Example of normal or nearly normal head skeleton (arrow). (B) Example of moderate to severe defects in the head skeleton (arrow), indicative of defects in head involution. (C) Example of a more severe phenotypic class, exhibiting either a head hole due to complete failure of head involution (arrow; illustrated here), a large dorsal hole, indicating failure of dorsal closure (not shown), or both. (D) Example of an embryo in which head involution failed (top arrow) and there was one or more holes in the dorsal cuticle (bottom arrow). (E) Example of the most severe phenotype, in which the remaining cuticle was fragmented. (F) Percentages of dead embryos in each phenotypic class for different genetic interaction crosses. Note that this actually underestimates the enhancement of the ena phenotype by reduction of Pyd levels, as not all ena zygotic mutant embryos die (19% relative to 25% expected from the cross), whereas essentially all ena zygotic mutants with reduced Pyd die (25% relative to 25% expected). Presumably those ena zygotic mutants that hatch as larvae have an essentially wild-type cuticle phenotype. Scale bar, 75 μm.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Figure 12: pyd and ena also exhibit strong, dose-sensitive genetic interactions. (A–E) Cuticles of embryos, exhibiting representative phenotypes scored in the different genotypes. (A) Example of normal or nearly normal head skeleton (arrow). (B) Example of moderate to severe defects in the head skeleton (arrow), indicative of defects in head involution. (C) Example of a more severe phenotypic class, exhibiting either a head hole due to complete failure of head involution (arrow; illustrated here), a large dorsal hole, indicating failure of dorsal closure (not shown), or both. (D) Example of an embryo in which head involution failed (top arrow) and there was one or more holes in the dorsal cuticle (bottom arrow). (E) Example of the most severe phenotype, in which the remaining cuticle was fragmented. (F) Percentages of dead embryos in each phenotypic class for different genetic interaction crosses. Note that this actually underestimates the enhancement of the ena phenotype by reduction of Pyd levels, as not all ena zygotic mutant embryos die (19% relative to 25% expected from the cross), whereas essentially all ena zygotic mutants with reduced Pyd die (25% relative to 25% expected). Presumably those ena zygotic mutants that hatch as larvae have an essentially wild-type cuticle phenotype. Scale bar, 75 μm.
Mentions: We next explored whether ena genetically interacts with pyd. As we observed with Cno, reducing Pyd levels (by crossing ena/+;pyd/+ males and females) strongly enhanced the morphogenesis defects of zygotic ena mutants, substantially increasing the frequency of failure of head involution (Figure 12F, bottom four genotypes). This was true for two different pyd alleles, pydB12 and pydex180. In addition, reducing Ena levels also substantially enhanced the severity of the pydMZ phenotype; more than one-third of the mutants now exhibited large holes in the cuticle, suggesting disruption of epithelial integrity (Figure 12F, top two genotypes). The dose-sensitive genetic interactions of ena with both cno and pyd are consistent with those seen with joint reduction of proteins in the same pathway and support the hypothesis that Cno and Pyd work with or through Ena during embryonic morphogenesis.

Bottom Line: Pyd loss does not dramatically affect AJ protein localization or initial localization of actin and myosin during dorsal closure.The defects, which include segmental grooves that fail to retract, a disrupted leading edge actin cable, and reduced zippering as leading edges meet, closely resemble defects in canoe zygotic mutants and in embryos lacking the actin regulator Enabled (Ena), suggesting that these proteins act together.Canoe (Cno) and Pyd are required for proper Ena localization during dorsal closure, and strong genetic interactions suggest that Cno, Pyd, and Ena act together in regulating or anchoring the actin cytoskeleton during dorsal closure.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of North Carolina at Chapel Hill, USA.

ABSTRACT
Adherens and tight junctions play key roles in assembling epithelia and maintaining barriers. In cell culture zonula occludens (ZO)-family proteins are important for assembly/maturation of both tight and adherens junctions (AJs). Genetic studies suggest that ZO proteins are important during normal development, but interpretation of mouse and fly studies is limited by genetic redundancy and/or a lack of alleles. We generated alleles of the single Drosophila ZO protein Polychaetoid (Pyd). Most embryos lacking Pyd die with striking defects in morphogenesis of embryonic epithelia including the epidermis, segmental grooves, and tracheal system. Pyd loss does not dramatically affect AJ protein localization or initial localization of actin and myosin during dorsal closure. However, Pyd loss does affect several cell behaviors that drive dorsal closure. The defects, which include segmental grooves that fail to retract, a disrupted leading edge actin cable, and reduced zippering as leading edges meet, closely resemble defects in canoe zygotic mutants and in embryos lacking the actin regulator Enabled (Ena), suggesting that these proteins act together. Canoe (Cno) and Pyd are required for proper Ena localization during dorsal closure, and strong genetic interactions suggest that Cno, Pyd, and Ena act together in regulating or anchoring the actin cytoskeleton during dorsal closure.

Show MeSH