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Binding site for p120/delta-catenin is not required for Drosophila E-cadherin function in vivo.

Pacquelet A, Lin L, Rorth P - J. Cell Biol. (2003)

Bottom Line: As expected, DE-cadherin-Delta beta did not substitute for DE-cadherin in these processes, although it retained some residual activity.Surprisingly, DE-cadherin-AAA was able to substitute for the wild-type protein in all contexts with no detectable perturbations.Thus, interaction with p120/delta-catenin does not appear to be required for DE-cadherin function in vivo.

View Article: PubMed Central - PubMed

Affiliation: European Molecular Biology Laboratory, 69117 Heidelberg, Germany.

ABSTRACT
Homophilic cell adhesion mediated by classical cadherins is important for many developmental processes. Proteins that interact with the cytoplasmic domain of cadherin, in particular the catenins, are thought to regulate the strength and possibly the dynamics of adhesion. beta-catenin links cadherin to the actin cytoskeleton via alpha-catenin. The role of p120/delta-catenin proteins in regulating cadherin function is less clear. Both beta-catenin and p120/delta-catenin are conserved in Drosophila. Here, we address the importance of cadherin-catenin interactions in vivo, using mutant variants of Drosophila epithelial cadherin (DE-cadherin) that are selectively defective in p120ctn (DE-cadherin-AAA) or beta-catenin-armadillo (DE-cadherin-Delta beta) interactions. We have analyzed the ability of these proteins to substitute for endogenous DE-cadherin activity in multiple cadherin-dependent processes during Drosophila development and oogenesis; epithelial integrity, follicle cell sorting, oocyte positioning, as well as the dynamic adhesion required for border cell migration. As expected, DE-cadherin-Delta beta did not substitute for DE-cadherin in these processes, although it retained some residual activity. Surprisingly, DE-cadherin-AAA was able to substitute for the wild-type protein in all contexts with no detectable perturbations. Thus, interaction with p120/delta-catenin does not appear to be required for DE-cadherin function in vivo.

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Cortical recruitment of p120ctn and β-catenin by DE-cadherin variants in follicular cells. Localization of overexpressed HA-p120ctn (A–D, green, and A'–D') or endogenous β-catenin (E–H, green, and E'–H') in follicular cells expressing only endogenous DE-cadherin (A and E), or overexpressing DE-cadherin-wt (B and F), DE-cadherin-AAA (C and G) or DE-cadherin-Δβ (D and H; red). Levels of endogenous DE-cadherin are too low to recruit all overexpressed p120ctn to the cortex, except in cells where overexpression is milder (arrow). (A–D) Basal sections of the follicular epithelium are shown. UAS-HA-p120ctn and UAS-DE-cadherin transgenes were overexpressed with slboGal4 (Rørth et al., 1998). Bars, ∼20 μm.
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fig2: Cortical recruitment of p120ctn and β-catenin by DE-cadherin variants in follicular cells. Localization of overexpressed HA-p120ctn (A–D, green, and A'–D') or endogenous β-catenin (E–H, green, and E'–H') in follicular cells expressing only endogenous DE-cadherin (A and E), or overexpressing DE-cadherin-wt (B and F), DE-cadherin-AAA (C and G) or DE-cadherin-Δβ (D and H; red). Levels of endogenous DE-cadherin are too low to recruit all overexpressed p120ctn to the cortex, except in cells where overexpression is milder (arrow). (A–D) Basal sections of the follicular epithelium are shown. UAS-HA-p120ctn and UAS-DE-cadherin transgenes were overexpressed with slboGal4 (Rørth et al., 1998). Bars, ∼20 μm.

Mentions: To specifically disrupt the interaction between DE-cadherin and p120ctn, we mutated a conserved triplet of glycine in the juxtamembrane region of DE-cadherin to alanine (Fig. 1 A; DE-cadherin-AAA). The corresponding mutation in human E-cadherin disrupts the interaction with p120 without affecting the interaction with β-catenin (Thoreson et al., 2000). We also made a version of DE-cadherin that should be unable to interact with β-catenin by deleting the COOH-terminal β-catenin interaction domain (Fig. 1 A; DE-cadherin-Δβ). The mutant DE-cadherin molecules were tested by transfection in Schneider cells (Fig. 1) as well as by overexpression with the UAS-Gal4 system in the follicular epithelium of egg chambers (Fig. 2).


Binding site for p120/delta-catenin is not required for Drosophila E-cadherin function in vivo.

Pacquelet A, Lin L, Rorth P - J. Cell Biol. (2003)

Cortical recruitment of p120ctn and β-catenin by DE-cadherin variants in follicular cells. Localization of overexpressed HA-p120ctn (A–D, green, and A'–D') or endogenous β-catenin (E–H, green, and E'–H') in follicular cells expressing only endogenous DE-cadherin (A and E), or overexpressing DE-cadherin-wt (B and F), DE-cadherin-AAA (C and G) or DE-cadherin-Δβ (D and H; red). Levels of endogenous DE-cadherin are too low to recruit all overexpressed p120ctn to the cortex, except in cells where overexpression is milder (arrow). (A–D) Basal sections of the follicular epithelium are shown. UAS-HA-p120ctn and UAS-DE-cadherin transgenes were overexpressed with slboGal4 (Rørth et al., 1998). Bars, ∼20 μm.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172659&req=5

fig2: Cortical recruitment of p120ctn and β-catenin by DE-cadherin variants in follicular cells. Localization of overexpressed HA-p120ctn (A–D, green, and A'–D') or endogenous β-catenin (E–H, green, and E'–H') in follicular cells expressing only endogenous DE-cadherin (A and E), or overexpressing DE-cadherin-wt (B and F), DE-cadherin-AAA (C and G) or DE-cadherin-Δβ (D and H; red). Levels of endogenous DE-cadherin are too low to recruit all overexpressed p120ctn to the cortex, except in cells where overexpression is milder (arrow). (A–D) Basal sections of the follicular epithelium are shown. UAS-HA-p120ctn and UAS-DE-cadherin transgenes were overexpressed with slboGal4 (Rørth et al., 1998). Bars, ∼20 μm.
Mentions: To specifically disrupt the interaction between DE-cadherin and p120ctn, we mutated a conserved triplet of glycine in the juxtamembrane region of DE-cadherin to alanine (Fig. 1 A; DE-cadherin-AAA). The corresponding mutation in human E-cadherin disrupts the interaction with p120 without affecting the interaction with β-catenin (Thoreson et al., 2000). We also made a version of DE-cadherin that should be unable to interact with β-catenin by deleting the COOH-terminal β-catenin interaction domain (Fig. 1 A; DE-cadherin-Δβ). The mutant DE-cadherin molecules were tested by transfection in Schneider cells (Fig. 1) as well as by overexpression with the UAS-Gal4 system in the follicular epithelium of egg chambers (Fig. 2).

Bottom Line: As expected, DE-cadherin-Delta beta did not substitute for DE-cadherin in these processes, although it retained some residual activity.Surprisingly, DE-cadherin-AAA was able to substitute for the wild-type protein in all contexts with no detectable perturbations.Thus, interaction with p120/delta-catenin does not appear to be required for DE-cadherin function in vivo.

View Article: PubMed Central - PubMed

Affiliation: European Molecular Biology Laboratory, 69117 Heidelberg, Germany.

ABSTRACT
Homophilic cell adhesion mediated by classical cadherins is important for many developmental processes. Proteins that interact with the cytoplasmic domain of cadherin, in particular the catenins, are thought to regulate the strength and possibly the dynamics of adhesion. beta-catenin links cadherin to the actin cytoskeleton via alpha-catenin. The role of p120/delta-catenin proteins in regulating cadherin function is less clear. Both beta-catenin and p120/delta-catenin are conserved in Drosophila. Here, we address the importance of cadherin-catenin interactions in vivo, using mutant variants of Drosophila epithelial cadherin (DE-cadherin) that are selectively defective in p120ctn (DE-cadherin-AAA) or beta-catenin-armadillo (DE-cadherin-Delta beta) interactions. We have analyzed the ability of these proteins to substitute for endogenous DE-cadherin activity in multiple cadherin-dependent processes during Drosophila development and oogenesis; epithelial integrity, follicle cell sorting, oocyte positioning, as well as the dynamic adhesion required for border cell migration. As expected, DE-cadherin-Delta beta did not substitute for DE-cadherin in these processes, although it retained some residual activity. Surprisingly, DE-cadherin-AAA was able to substitute for the wild-type protein in all contexts with no detectable perturbations. Thus, interaction with p120/delta-catenin does not appear to be required for DE-cadherin function in vivo.

Show MeSH
Related in: MedlinePlus