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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.

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

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PAPC-dependent PCP inhibition at boundary. (A and B) Quantitation of tissue separation using Xenopus (A) and zebrafish (B) mesoderm test explants. (C) Inferred control pathway. (D–F) Localization of Dvl2-GFP and Pk1-venus in Xenopus. Yellow arrowheads indicate puncta in mesoderm (green); white arrowheads indicate boundary to ectoderm; ectoderm is labeled with membrane-RFP (red). 27 (E) and 20 (F) explant boundaries were evaluated in I. (G and H) Behavior of Dvl-GFP puncta at boundary to ectoderm in normal (G) or PAPC-MO–injected mesoderm (H). Arrowheads: blue, puncta appears, moves to interior, and disappears; yellow, moves to interior and stays; green, stable puncta; purple, cluster of fusing puncta. Of a total of 27 (G) or 18 (H) explant boundaries, 4 and 3, respectively, were filmed. (I) Puncta per cell at boundary. n, number of cells examined at 9–27 different explant boundaries per experimental treatment. Standard deviations indicate variability between individual cells. Averages are increased significantly compared with mesoderm Dvl-GFP or Pk1-venus at boundary (first two columns; t test, P < 0.0001 in all cases) except M-PAPC in ectoderm (last column, P = 0.111).
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fig5: PAPC-dependent PCP inhibition at boundary. (A and B) Quantitation of tissue separation using Xenopus (A) and zebrafish (B) mesoderm test explants. (C) Inferred control pathway. (D–F) Localization of Dvl2-GFP and Pk1-venus in Xenopus. Yellow arrowheads indicate puncta in mesoderm (green); white arrowheads indicate boundary to ectoderm; ectoderm is labeled with membrane-RFP (red). 27 (E) and 20 (F) explant boundaries were evaluated in I. (G and H) Behavior of Dvl-GFP puncta at boundary to ectoderm in normal (G) or PAPC-MO–injected mesoderm (H). Arrowheads: blue, puncta appears, moves to interior, and disappears; yellow, moves to interior and stays; green, stable puncta; purple, cluster of fusing puncta. Of a total of 27 (G) or 18 (H) explant boundaries, 4 and 3, respectively, were filmed. (I) Puncta per cell at boundary. n, number of cells examined at 9–27 different explant boundaries per experimental treatment. Standard deviations indicate variability between individual cells. Averages are increased significantly compared with mesoderm Dvl-GFP or Pk1-venus at boundary (first two columns; t test, P < 0.0001 in all cases) except M-PAPC in ectoderm (last column, P = 0.111).

Mentions: To analyze downstream effects of PAPC/Snail1 during tissue separation, we explored a seemingly paradoxical finding: Dvl2 was required for Xsnail1 expression, but Dvl2-MO did not block separation behavior (Fig. 5 A). One possibility is that Dvl2-MO inhibited Xsnail1 expression but rescued separation further downstream; indeed, Dvl2-MO rescued separation in Xsnail1-MO–injected as well as PTX-treated mesoderm (Fig. 5 A). The PCP component Prickle (Pk1) is up-regulated in Xenopus mesoderm (Takeuchi et al., 2003; Veeman et al., 2003) and in the axial mesoderm of zebrafish (Carreira-Barbosa et al., 2003). Pk1 knockdown, which neither blocked separation (Fig. 5 A) nor reduced Xsnail1 expression (Fig. S5 A), also rescued separation. The PCP component Vangl2/Stbm had similar effects (Fig. 5 A). In the zebrafish, Dvl2-MO and Pk-MO likewise rescued tissue separation (Fig. 5 B and Fig. S1 H).


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)

PAPC-dependent PCP inhibition at boundary. (A and B) Quantitation of tissue separation using Xenopus (A) and zebrafish (B) mesoderm test explants. (C) Inferred control pathway. (D–F) Localization of Dvl2-GFP and Pk1-venus in Xenopus. Yellow arrowheads indicate puncta in mesoderm (green); white arrowheads indicate boundary to ectoderm; ectoderm is labeled with membrane-RFP (red). 27 (E) and 20 (F) explant boundaries were evaluated in I. (G and H) Behavior of Dvl-GFP puncta at boundary to ectoderm in normal (G) or PAPC-MO–injected mesoderm (H). Arrowheads: blue, puncta appears, moves to interior, and disappears; yellow, moves to interior and stays; green, stable puncta; purple, cluster of fusing puncta. Of a total of 27 (G) or 18 (H) explant boundaries, 4 and 3, respectively, were filmed. (I) Puncta per cell at boundary. n, number of cells examined at 9–27 different explant boundaries per experimental treatment. Standard deviations indicate variability between individual cells. Averages are increased significantly compared with mesoderm Dvl-GFP or Pk1-venus at boundary (first two columns; t test, P < 0.0001 in all cases) except M-PAPC in ectoderm (last column, P = 0.111).
© Copyright Policy - openaccess
Related In: Results  -  Collection

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Show All Figures
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fig5: PAPC-dependent PCP inhibition at boundary. (A and B) Quantitation of tissue separation using Xenopus (A) and zebrafish (B) mesoderm test explants. (C) Inferred control pathway. (D–F) Localization of Dvl2-GFP and Pk1-venus in Xenopus. Yellow arrowheads indicate puncta in mesoderm (green); white arrowheads indicate boundary to ectoderm; ectoderm is labeled with membrane-RFP (red). 27 (E) and 20 (F) explant boundaries were evaluated in I. (G and H) Behavior of Dvl-GFP puncta at boundary to ectoderm in normal (G) or PAPC-MO–injected mesoderm (H). Arrowheads: blue, puncta appears, moves to interior, and disappears; yellow, moves to interior and stays; green, stable puncta; purple, cluster of fusing puncta. Of a total of 27 (G) or 18 (H) explant boundaries, 4 and 3, respectively, were filmed. (I) Puncta per cell at boundary. n, number of cells examined at 9–27 different explant boundaries per experimental treatment. Standard deviations indicate variability between individual cells. Averages are increased significantly compared with mesoderm Dvl-GFP or Pk1-venus at boundary (first two columns; t test, P < 0.0001 in all cases) except M-PAPC in ectoderm (last column, P = 0.111).
Mentions: To analyze downstream effects of PAPC/Snail1 during tissue separation, we explored a seemingly paradoxical finding: Dvl2 was required for Xsnail1 expression, but Dvl2-MO did not block separation behavior (Fig. 5 A). One possibility is that Dvl2-MO inhibited Xsnail1 expression but rescued separation further downstream; indeed, Dvl2-MO rescued separation in Xsnail1-MO–injected as well as PTX-treated mesoderm (Fig. 5 A). The PCP component Prickle (Pk1) is up-regulated in Xenopus mesoderm (Takeuchi et al., 2003; Veeman et al., 2003) and in the axial mesoderm of zebrafish (Carreira-Barbosa et al., 2003). Pk1 knockdown, which neither blocked separation (Fig. 5 A) nor reduced Xsnail1 expression (Fig. S5 A), also rescued separation. The PCP component Vangl2/Stbm had similar effects (Fig. 5 A). In the zebrafish, Dvl2-MO and Pk-MO likewise rescued tissue separation (Fig. 5 B and Fig. S1 H).

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