Limits...
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.

Show MeSH

Related in: MedlinePlus

Expression of tubulin-DE-cadherin transgenes in the ovary. (A–D) Follicular epithelium from females carrying tubulin-DE-cadherin-wt (A), tubulin-DE-cadherin-AAA-#6 (B), tubulin-DE-cadherin-Δβ (C), or tubulin-DE-cadherin-AAA-#7 (D). Absence of GFP (green) marks shg mutant cells. Cadherin is in red and endogenous β-catenin in blue. A''–C'' show that DE-cadherin-wt and DE-cadherin-AAA recruit endogenous β-catenin even in the absence of endogenous DE-cadherin. Bars, ∼10 μm. (E–F) Expression levels of DE-cadherin-AAA-#6 (E and E') and #7 (F and F') in border cells were estimated by comparison of DE-cadherin levels at the inner membranes of border cells (arrow) in shg mutant cells (E' and F') and non mutant cells (E and F). Bars, ∼10 μm. (G–J) DE-cadherin in nurse cells expressing only the indicated tubulin-DE-cadherin transgene (G–I, germ line cells are shg mutant clones) or only endogenous DE-cadherin (J). Bars, ∼20 μm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2172659&req=5

fig3: Expression of tubulin-DE-cadherin transgenes in the ovary. (A–D) Follicular epithelium from females carrying tubulin-DE-cadherin-wt (A), tubulin-DE-cadherin-AAA-#6 (B), tubulin-DE-cadherin-Δβ (C), or tubulin-DE-cadherin-AAA-#7 (D). Absence of GFP (green) marks shg mutant cells. Cadherin is in red and endogenous β-catenin in blue. A''–C'' show that DE-cadherin-wt and DE-cadherin-AAA recruit endogenous β-catenin even in the absence of endogenous DE-cadherin. Bars, ∼10 μm. (E–F) Expression levels of DE-cadherin-AAA-#6 (E and E') and #7 (F and F') in border cells were estimated by comparison of DE-cadherin levels at the inner membranes of border cells (arrow) in shg mutant cells (E' and F') and non mutant cells (E and F). Bars, ∼10 μm. (G–J) DE-cadherin in nurse cells expressing only the indicated tubulin-DE-cadherin transgene (G–I, germ line cells are shg mutant clones) or only endogenous DE-cadherin (J). Bars, ∼20 μm.

Mentions: To analyze the biological activity of the mutant DE-cadherin proteins during development, the following strategy was used to replace endogenous DE-cadherin with mutant forms: We generated transgenic flies that express DE-cadherin-wt, DE-cadherin-AAA, or DE-cadherin-Δβ ubiquitously, under the control of the tubulin-α1 promoter. Endogenous DE-cadherin was removed from specific cells by generating homozygous shg mutant clones or zygotic expression was removed by analyzing shg homozygous mutant embryos. Both shg alleles used in this study are strong alleles, one (shgR69) is a molecular allele. Next, we determined whether the transgene-encoded DE-cadherin could substitute for endogenous DE-cadherin, that is, rescue the shg mutant phenotype. Membrane localization and expression levels were checked by immunostaining of egg chambers containing patches of shg mutant cells. These cells expressed only the transgene-encoded DE-cadherin, allowing comparison with endogenous levels (Fig. 3). In follicle cells, DE-cadherin-wt transgenes and one of the DE-cadherin-AAA transgenes (#6) were expressed at somewhat higher levels than endogenous DE-cadherin (Fig. 3, A and B). Another DE-cadherin-AAA transgene (#7) and DE-cadherin-Δβ transgenes gave similar levels of expression, slightly lower than endogenous DE-cadherin (Fig. 3, C and D). In nurse cells, DE-cadherin-Δβ transgenes gave expression levels similar to endogenous DE-cadherin, whereas DE-cadherin-wt and both DE-cadherin-AAA transgenes were expressed at much higher levels (Fig. 3, G–J)


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)

Expression of tubulin-DE-cadherin transgenes in the ovary. (A–D) Follicular epithelium from females carrying tubulin-DE-cadherin-wt (A), tubulin-DE-cadherin-AAA-#6 (B), tubulin-DE-cadherin-Δβ (C), or tubulin-DE-cadherin-AAA-#7 (D). Absence of GFP (green) marks shg mutant cells. Cadherin is in red and endogenous β-catenin in blue. A''–C'' show that DE-cadherin-wt and DE-cadherin-AAA recruit endogenous β-catenin even in the absence of endogenous DE-cadherin. Bars, ∼10 μm. (E–F) Expression levels of DE-cadherin-AAA-#6 (E and E') and #7 (F and F') in border cells were estimated by comparison of DE-cadherin levels at the inner membranes of border cells (arrow) in shg mutant cells (E' and F') and non mutant cells (E and F). Bars, ∼10 μm. (G–J) DE-cadherin in nurse cells expressing only the indicated tubulin-DE-cadherin transgene (G–I, germ line cells are shg mutant clones) or only endogenous DE-cadherin (J). Bars, ∼20 μm.
© Copyright Policy
Related In: Results  -  Collection

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

fig3: Expression of tubulin-DE-cadherin transgenes in the ovary. (A–D) Follicular epithelium from females carrying tubulin-DE-cadherin-wt (A), tubulin-DE-cadherin-AAA-#6 (B), tubulin-DE-cadherin-Δβ (C), or tubulin-DE-cadherin-AAA-#7 (D). Absence of GFP (green) marks shg mutant cells. Cadherin is in red and endogenous β-catenin in blue. A''–C'' show that DE-cadherin-wt and DE-cadherin-AAA recruit endogenous β-catenin even in the absence of endogenous DE-cadherin. Bars, ∼10 μm. (E–F) Expression levels of DE-cadherin-AAA-#6 (E and E') and #7 (F and F') in border cells were estimated by comparison of DE-cadherin levels at the inner membranes of border cells (arrow) in shg mutant cells (E' and F') and non mutant cells (E and F). Bars, ∼10 μm. (G–J) DE-cadherin in nurse cells expressing only the indicated tubulin-DE-cadherin transgene (G–I, germ line cells are shg mutant clones) or only endogenous DE-cadherin (J). Bars, ∼20 μm.
Mentions: To analyze the biological activity of the mutant DE-cadherin proteins during development, the following strategy was used to replace endogenous DE-cadherin with mutant forms: We generated transgenic flies that express DE-cadherin-wt, DE-cadherin-AAA, or DE-cadherin-Δβ ubiquitously, under the control of the tubulin-α1 promoter. Endogenous DE-cadherin was removed from specific cells by generating homozygous shg mutant clones or zygotic expression was removed by analyzing shg homozygous mutant embryos. Both shg alleles used in this study are strong alleles, one (shgR69) is a molecular allele. Next, we determined whether the transgene-encoded DE-cadherin could substitute for endogenous DE-cadherin, that is, rescue the shg mutant phenotype. Membrane localization and expression levels were checked by immunostaining of egg chambers containing patches of shg mutant cells. These cells expressed only the transgene-encoded DE-cadherin, allowing comparison with endogenous levels (Fig. 3). In follicle cells, DE-cadherin-wt transgenes and one of the DE-cadherin-AAA transgenes (#6) were expressed at somewhat higher levels than endogenous DE-cadherin (Fig. 3, A and B). Another DE-cadherin-AAA transgene (#7) and DE-cadherin-Δβ transgenes gave similar levels of expression, slightly lower than endogenous DE-cadherin (Fig. 3, C and D). In nurse cells, DE-cadherin-Δβ transgenes gave expression levels similar to endogenous DE-cadherin, whereas DE-cadherin-wt and both DE-cadherin-AAA transgenes were expressed at much higher levels (Fig. 3, G–J)

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