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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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cno zygotic  mutants can assemble a leading edge actomyosin cable but it is discontinuous in many embryos. Stage 13–15 wild-type (WT) embryo or cnoR2 zygotic mutants, anterior left, dorsal up, antigens indicated. (A, B) Stage 13. Cno protein levels start to decline in cno zygotic mutants (B; imaged on same slide and settings as heterozygous sibling control in A). (C, D) Stage 15. Cno substantially reduced but still detectable in cno mutants (D). (E, F) Early stage 14. Actin and DE-cad staining, labeled top to bottom. Arrow, leading edge actin cable. (G, H). Late stage 14. Arm and nonmuscle myosin II (Myo) staining, labeled top to bottom. Arrow, leading edge myosin cable. (I) Late stage 14. In some mutants, the actin cable becomes discontinuous; it is reduced or lost in cells with widened leading edges. (J, K) Late stage 14. Like wild-type embryos, cno mutants accumulate elevated levels of myosin VI in the cytoplasm of LE cells (brackets) and particularly at the leading edge (arrows). (L, M) Stage 15. Pyd levels and localization are unaltered in cno mutants. Scale bars, 10 μm.
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Figure 8: cno zygotic mutants can assemble a leading edge actomyosin cable but it is discontinuous in many embryos. Stage 13–15 wild-type (WT) embryo or cnoR2 zygotic mutants, anterior left, dorsal up, antigens indicated. (A, B) Stage 13. Cno protein levels start to decline in cno zygotic mutants (B; imaged on same slide and settings as heterozygous sibling control in A). (C, D) Stage 15. Cno substantially reduced but still detectable in cno mutants (D). (E, F) Early stage 14. Actin and DE-cad staining, labeled top to bottom. Arrow, leading edge actin cable. (G, H). Late stage 14. Arm and nonmuscle myosin II (Myo) staining, labeled top to bottom. Arrow, leading edge myosin cable. (I) Late stage 14. In some mutants, the actin cable becomes discontinuous; it is reduced or lost in cells with widened leading edges. (J, K) Late stage 14. Like wild-type embryos, cno mutants accumulate elevated levels of myosin VI in the cytoplasm of LE cells (brackets) and particularly at the leading edge (arrows). (L, M) Stage 15. Pyd levels and localization are unaltered in cno mutants. Scale bars, 10 μm.

Mentions: We thus compared effects of Cno reduction on dorsal closure with that of loss of Pyd. cnoR2 zygotic mutants (henceforth called cno mutants, for simplicity) have a high frequency of defects in head involution and a lower frequency of defects in completing dorsal closure (Sawyer et al., 2009). We first examined how rapidly maternally contributed Cno disappeared in zygotic mutants. Mutants began to be distinguishable from heterozygous siblings at stage 13 (Figure 8, A’ vs. B’), and zygotic mutants retain reduced though detectable levels of Cno protein through the end of dorsal closure (Figure 8, C’ vs. D’).


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)

cno zygotic  mutants can assemble a leading edge actomyosin cable but it is discontinuous in many embryos. Stage 13–15 wild-type (WT) embryo or cnoR2 zygotic mutants, anterior left, dorsal up, antigens indicated. (A, B) Stage 13. Cno protein levels start to decline in cno zygotic mutants (B; imaged on same slide and settings as heterozygous sibling control in A). (C, D) Stage 15. Cno substantially reduced but still detectable in cno mutants (D). (E, F) Early stage 14. Actin and DE-cad staining, labeled top to bottom. Arrow, leading edge actin cable. (G, H). Late stage 14. Arm and nonmuscle myosin II (Myo) staining, labeled top to bottom. Arrow, leading edge myosin cable. (I) Late stage 14. In some mutants, the actin cable becomes discontinuous; it is reduced or lost in cells with widened leading edges. (J, K) Late stage 14. Like wild-type embryos, cno mutants accumulate elevated levels of myosin VI in the cytoplasm of LE cells (brackets) and particularly at the leading edge (arrows). (L, M) Stage 15. Pyd levels and localization are unaltered in cno mutants. Scale bars, 10 μm.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Figure 8: cno zygotic mutants can assemble a leading edge actomyosin cable but it is discontinuous in many embryos. Stage 13–15 wild-type (WT) embryo or cnoR2 zygotic mutants, anterior left, dorsal up, antigens indicated. (A, B) Stage 13. Cno protein levels start to decline in cno zygotic mutants (B; imaged on same slide and settings as heterozygous sibling control in A). (C, D) Stage 15. Cno substantially reduced but still detectable in cno mutants (D). (E, F) Early stage 14. Actin and DE-cad staining, labeled top to bottom. Arrow, leading edge actin cable. (G, H). Late stage 14. Arm and nonmuscle myosin II (Myo) staining, labeled top to bottom. Arrow, leading edge myosin cable. (I) Late stage 14. In some mutants, the actin cable becomes discontinuous; it is reduced or lost in cells with widened leading edges. (J, K) Late stage 14. Like wild-type embryos, cno mutants accumulate elevated levels of myosin VI in the cytoplasm of LE cells (brackets) and particularly at the leading edge (arrows). (L, M) Stage 15. Pyd levels and localization are unaltered in cno mutants. Scale bars, 10 μm.
Mentions: We thus compared effects of Cno reduction on dorsal closure with that of loss of Pyd. cnoR2 zygotic mutants (henceforth called cno mutants, for simplicity) have a high frequency of defects in head involution and a lower frequency of defects in completing dorsal closure (Sawyer et al., 2009). We first examined how rapidly maternally contributed Cno disappeared in zygotic mutants. Mutants began to be distinguishable from heterozygous siblings at stage 13 (Figure 8, A’ vs. B’), and zygotic mutants retain reduced though detectable levels of Cno protein through the end of dorsal closure (Figure 8, C’ vs. D’).

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