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PAPC mediates self/non-self-distinction during Snail1-dependent tissue separation.

Luu O, Damm EW, Parent SE, Barua D, Smith TH, Wen JW, Lepage SE, Nagel M, Ibrahim-Gawel H, Huang Y, Bruce AE, Winklbauer R - J. Cell Biol. (2015)

Bottom Line: First, PAPC attenuates planar cell polarity signaling at the ectoderm-mesoderm boundary to lower cell adhesion and facilitate cleft formation.It consists of short stretches of adherens junction-like contacts inserted between intermediate-sized contacts and large intercellular gaps.These roles of PAPC constitute a self/non-self-recognition mechanism that determines the site of boundary formation at the interface between PAPC-expressing and -nonexpressing cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada M5S 3G5.

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Snail1 function in tissue separation. (A–C) Brachet’s cleft in sagittally fractured stage 10.5 Xenopus gastrulae. Uninjected embryos (A); cleft (between red arrowheads) is shortened by Xsnail1-MO (B), but not Xsnail1-MO/Xsnail1 mRNA coinjection (C). Yellow arrows indicate the blastopore. C, chordamesoderm; P, prechordal mesoderm; L, leading edge mesendoderm; n, number of embryos. (D–F) BCR assay for separation behavior in Xenopus. Prechordal mesoderm explants injected with control Sna1-misMO (D), Xsnail1-MO (E), or Xsnail1-MO and Xsnail1 mRNA (F) are placed on explanted BCR. Explants sunken after 1 h in E are indicated by arrowheads. (G) Outline of BCR assay. (H) Quantitation of BCR assay. Y axis, percentage of test explants remaining on surface; n, number of explants. (I–K) Tissue separation in zebrafish. (I) Quantitation of separation behavior as in H. (J) Brachet’s cleft in live embryos (left panels) and SEM micrographs (right panels) at 75% epiboly in wild-type and snai1a-misMO– and snail1a MO–injected embryos. Red arrowheads indicate Brachet’s cleft; n, number of embryos. (K) In vitro assay, differential interference contrast images, and fluorescence overlay images at explanation (left) and 45 min later (right). Epiblast test explant (blue arrowheads) sinks into the epiblast, and fluorescent hypoblast explant (yellow arrowheads) remains on the surface.
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fig1: Snail1 function in tissue separation. (A–C) Brachet’s cleft in sagittally fractured stage 10.5 Xenopus gastrulae. Uninjected embryos (A); cleft (between red arrowheads) is shortened by Xsnail1-MO (B), but not Xsnail1-MO/Xsnail1 mRNA coinjection (C). Yellow arrows indicate the blastopore. C, chordamesoderm; P, prechordal mesoderm; L, leading edge mesendoderm; n, number of embryos. (D–F) BCR assay for separation behavior in Xenopus. Prechordal mesoderm explants injected with control Sna1-misMO (D), Xsnail1-MO (E), or Xsnail1-MO and Xsnail1 mRNA (F) are placed on explanted BCR. Explants sunken after 1 h in E are indicated by arrowheads. (G) Outline of BCR assay. (H) Quantitation of BCR assay. Y axis, percentage of test explants remaining on surface; n, number of explants. (I–K) Tissue separation in zebrafish. (I) Quantitation of separation behavior as in H. (J) Brachet’s cleft in live embryos (left panels) and SEM micrographs (right panels) at 75% epiboly in wild-type and snai1a-misMO– and snail1a MO–injected embryos. Red arrowheads indicate Brachet’s cleft; n, number of embryos. (K) In vitro assay, differential interference contrast images, and fluorescence overlay images at explanation (left) and 45 min later (right). Epiblast test explant (blue arrowheads) sinks into the epiblast, and fluorescent hypoblast explant (yellow arrowheads) remains on the surface.

Mentions: Xsnail1 is expressed in the mesoderm of Xenopus gastrulae (Essex et al., 1993). To identify its function, morpholino antisense oligonucleotides (MOs) were injected into dorsal blastomeres. In uninjected or 5-mismatch control MO (5mis-MO)–injected embryos, Brachet’s cleft separated the prechordal mesoderm from the ectodermal BCR (Fig. 1 A). Injection of Snail1-MO eliminated cleft formation in this region (Fig. 1 B), and coinjection of Xsnail1 mRNA rescued it (Fig. 1 C), suggesting that Xsnail1 is required for tissue separation. Cleft defects in Xsnail1 morphants were not accompanied by any noticeable changes in mesoderm specification (Fig. S1, A–D).


PAPC mediates self/non-self-distinction during Snail1-dependent tissue separation.

Luu O, Damm EW, Parent SE, Barua D, Smith TH, Wen JW, Lepage SE, Nagel M, Ibrahim-Gawel H, Huang Y, Bruce AE, Winklbauer R - J. Cell Biol. (2015)

Snail1 function in tissue separation. (A–C) Brachet’s cleft in sagittally fractured stage 10.5 Xenopus gastrulae. Uninjected embryos (A); cleft (between red arrowheads) is shortened by Xsnail1-MO (B), but not Xsnail1-MO/Xsnail1 mRNA coinjection (C). Yellow arrows indicate the blastopore. C, chordamesoderm; P, prechordal mesoderm; L, leading edge mesendoderm; n, number of embryos. (D–F) BCR assay for separation behavior in Xenopus. Prechordal mesoderm explants injected with control Sna1-misMO (D), Xsnail1-MO (E), or Xsnail1-MO and Xsnail1 mRNA (F) are placed on explanted BCR. Explants sunken after 1 h in E are indicated by arrowheads. (G) Outline of BCR assay. (H) Quantitation of BCR assay. Y axis, percentage of test explants remaining on surface; n, number of explants. (I–K) Tissue separation in zebrafish. (I) Quantitation of separation behavior as in H. (J) Brachet’s cleft in live embryos (left panels) and SEM micrographs (right panels) at 75% epiboly in wild-type and snai1a-misMO– and snail1a MO–injected embryos. Red arrowheads indicate Brachet’s cleft; n, number of embryos. (K) In vitro assay, differential interference contrast images, and fluorescence overlay images at explanation (left) and 45 min later (right). Epiblast test explant (blue arrowheads) sinks into the epiblast, and fluorescent hypoblast explant (yellow arrowheads) remains on the surface.
© Copyright Policy - openaccess
Related In: Results  -  Collection

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Show All Figures
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fig1: Snail1 function in tissue separation. (A–C) Brachet’s cleft in sagittally fractured stage 10.5 Xenopus gastrulae. Uninjected embryos (A); cleft (between red arrowheads) is shortened by Xsnail1-MO (B), but not Xsnail1-MO/Xsnail1 mRNA coinjection (C). Yellow arrows indicate the blastopore. C, chordamesoderm; P, prechordal mesoderm; L, leading edge mesendoderm; n, number of embryos. (D–F) BCR assay for separation behavior in Xenopus. Prechordal mesoderm explants injected with control Sna1-misMO (D), Xsnail1-MO (E), or Xsnail1-MO and Xsnail1 mRNA (F) are placed on explanted BCR. Explants sunken after 1 h in E are indicated by arrowheads. (G) Outline of BCR assay. (H) Quantitation of BCR assay. Y axis, percentage of test explants remaining on surface; n, number of explants. (I–K) Tissue separation in zebrafish. (I) Quantitation of separation behavior as in H. (J) Brachet’s cleft in live embryos (left panels) and SEM micrographs (right panels) at 75% epiboly in wild-type and snai1a-misMO– and snail1a MO–injected embryos. Red arrowheads indicate Brachet’s cleft; n, number of embryos. (K) In vitro assay, differential interference contrast images, and fluorescence overlay images at explanation (left) and 45 min later (right). Epiblast test explant (blue arrowheads) sinks into the epiblast, and fluorescent hypoblast explant (yellow arrowheads) remains on the surface.
Mentions: Xsnail1 is expressed in the mesoderm of Xenopus gastrulae (Essex et al., 1993). To identify its function, morpholino antisense oligonucleotides (MOs) were injected into dorsal blastomeres. In uninjected or 5-mismatch control MO (5mis-MO)–injected embryos, Brachet’s cleft separated the prechordal mesoderm from the ectodermal BCR (Fig. 1 A). Injection of Snail1-MO eliminated cleft formation in this region (Fig. 1 B), and coinjection of Xsnail1 mRNA rescued it (Fig. 1 C), suggesting that Xsnail1 is required for tissue separation. Cleft defects in Xsnail1 morphants were not accompanied by any noticeable changes in mesoderm specification (Fig. S1, A–D).

Bottom Line: First, PAPC attenuates planar cell polarity signaling at the ectoderm-mesoderm boundary to lower cell adhesion and facilitate cleft formation.It consists of short stretches of adherens junction-like contacts inserted between intermediate-sized contacts and large intercellular gaps.These roles of PAPC constitute a self/non-self-recognition mechanism that determines the site of boundary formation at the interface between PAPC-expressing and -nonexpressing cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada M5S 3G5.

Show MeSH
Related in: MedlinePlus