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Drosophila p120catenin plays a supporting role in cell adhesion but is not an essential adherens junction component.

Myster SH, Cavallo R, Anderson CT, Fox DT, Peifer M - J. Cell Biol. (2003)

Bottom Line: We generated alleles of p120 and found that mutants are viable and fertile and have no substantial changes in junction structure or function.However, p120 mutations strongly enhance mutations in the genes encoding DE-cadherin or Armadillo, the beta-catenin homologue.Finally, we examined the localization of p120 during embryogenesis. p120 localizes to adherens junctions, but its localization there is less universal than that of core adherens junction proteins.

View Article: PubMed Central - PubMed

Affiliation: Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.

ABSTRACT
Cadherin-catenin complexes, localized to adherens junctions, are essential for cell-cell adhesion. One means of regulating adhesion is through the juxtamembrane domain of the cadherin cytoplasmic tail. This region is the binding site for p120, leading to the hypothesis that p120 is a key regulator of cell adhesion. p120 has also been suggested to regulate the GTPase Rho and to regulate transcription via its binding partner Kaiso. To test these hypothesized functions, we turned to Drosophila, which has only a single p120 family member. It localizes to adherens junctions and binds the juxtamembrane region of DE-cadherin (DE-cad). We generated alleles of p120 and found that mutants are viable and fertile and have no substantial changes in junction structure or function. However, p120 mutations strongly enhance mutations in the genes encoding DE-cadherin or Armadillo, the beta-catenin homologue. Finally, we examined the localization of p120 during embryogenesis. p120 localizes to adherens junctions, but its localization there is less universal than that of core adherens junction proteins. Together, these data suggest that p120 is an important positive modulator of adhesion but that it is not an essential core component of adherens junctions.

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p120 mutations strongly enhance shg and arm. Cuticle preps, anterior up. (A) Wild-type. Note alternating denticle bands and naked cuticle on the ventral epidermis and normal head exoskeleton (top). (B) shgg119. Note head involution defects (arrow) but intact ventral epidermis. (C) Zygotic shgg119 p120308. Note hole in ventral epidermis. (D) Zygotic shgg119 p120308 mutant that is also maternally p120308 mutant. The entire ventral epidermis is lost. (E) shgR69. Ventral epidermis is lost, but dorsal and lateral epidermis remain. (F) Zygotic shgR69 p120308. Dorsal epidermis is disrupted (arrow). (G) Zygotic shgR69 p120308 mutant that was also maternally p120308 mutant. The remaining cuticle is fragmented. (H) shg2. Note holes in ventral epidermis. (I) Zygotic shg2 p120308. Note complete loss of ventral epidermis. (J) armYD35. Note shortened body and lawn of denticles ventrally (arrowhead), and defects in dorsal closure (arrow). (K and L) Zygotic armYD35 p120308 mutant that was also maternally p120308 mutant. Cuticles are longer, and in L dorsal closure defects are suppressed.
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fig6: p120 mutations strongly enhance shg and arm. Cuticle preps, anterior up. (A) Wild-type. Note alternating denticle bands and naked cuticle on the ventral epidermis and normal head exoskeleton (top). (B) shgg119. Note head involution defects (arrow) but intact ventral epidermis. (C) Zygotic shgg119 p120308. Note hole in ventral epidermis. (D) Zygotic shgg119 p120308 mutant that is also maternally p120308 mutant. The entire ventral epidermis is lost. (E) shgR69. Ventral epidermis is lost, but dorsal and lateral epidermis remain. (F) Zygotic shgR69 p120308. Dorsal epidermis is disrupted (arrow). (G) Zygotic shgR69 p120308 mutant that was also maternally p120308 mutant. The remaining cuticle is fragmented. (H) shg2. Note holes in ventral epidermis. (I) Zygotic shg2 p120308. Note complete loss of ventral epidermis. (J) armYD35. Note shortened body and lawn of denticles ventrally (arrowhead), and defects in dorsal closure (arrow). (K and L) Zygotic armYD35 p120308 mutant that was also maternally p120308 mutant. Cuticles are longer, and in L dorsal closure defects are suppressed.

Mentions: In both situations, we saw genetic interactions consistent with p120 playing a positive role in modulating AJ function. Mutations in p120 strongly enhanced the phenotypes of shg mutants. Wild-type larvae are entirely enclosed in cuticle (Fig. 6 A). To make a proper cuticle, epithelial tissues must retain their integrity and morphogenetic movements such as head involution and dorsal closure must occur properly. Zygotic loss-of-function mutations in shg disrupt morphogenesis and epithelial integrity (Tepass et al., 1996; Uemura et al., 1996), with different processes differentially sensitive to the level of remaining DE-cad function (in all cases, maternal wild-type DE-cad remains, since without it oogenesis is disrupted, and thus this is the phenotype of DE-cad depletion, not its total absence). A weak allele (shgg119) primarily has defects in head involution such that the embryo secretes cuticle without head structures (Fig. 6 B). A stronger allele (shg2) has holes in the ventral cuticle (Fig. 6 H): ventral neurectoderm is more sensitive to reductions in DE-cad function due to stresses imposed by the ingression of neural cells (Tepass et al., 1996). Most zygotic mutants (shgR69) secrete only a sheet of dorsal cuticle (Fig. 6 E) due to disruption of the integrity of the ventral epidermis.


Drosophila p120catenin plays a supporting role in cell adhesion but is not an essential adherens junction component.

Myster SH, Cavallo R, Anderson CT, Fox DT, Peifer M - J. Cell Biol. (2003)

p120 mutations strongly enhance shg and arm. Cuticle preps, anterior up. (A) Wild-type. Note alternating denticle bands and naked cuticle on the ventral epidermis and normal head exoskeleton (top). (B) shgg119. Note head involution defects (arrow) but intact ventral epidermis. (C) Zygotic shgg119 p120308. Note hole in ventral epidermis. (D) Zygotic shgg119 p120308 mutant that is also maternally p120308 mutant. The entire ventral epidermis is lost. (E) shgR69. Ventral epidermis is lost, but dorsal and lateral epidermis remain. (F) Zygotic shgR69 p120308. Dorsal epidermis is disrupted (arrow). (G) Zygotic shgR69 p120308 mutant that was also maternally p120308 mutant. The remaining cuticle is fragmented. (H) shg2. Note holes in ventral epidermis. (I) Zygotic shg2 p120308. Note complete loss of ventral epidermis. (J) armYD35. Note shortened body and lawn of denticles ventrally (arrowhead), and defects in dorsal closure (arrow). (K and L) Zygotic armYD35 p120308 mutant that was also maternally p120308 mutant. Cuticles are longer, and in L dorsal closure defects are suppressed.
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fig6: p120 mutations strongly enhance shg and arm. Cuticle preps, anterior up. (A) Wild-type. Note alternating denticle bands and naked cuticle on the ventral epidermis and normal head exoskeleton (top). (B) shgg119. Note head involution defects (arrow) but intact ventral epidermis. (C) Zygotic shgg119 p120308. Note hole in ventral epidermis. (D) Zygotic shgg119 p120308 mutant that is also maternally p120308 mutant. The entire ventral epidermis is lost. (E) shgR69. Ventral epidermis is lost, but dorsal and lateral epidermis remain. (F) Zygotic shgR69 p120308. Dorsal epidermis is disrupted (arrow). (G) Zygotic shgR69 p120308 mutant that was also maternally p120308 mutant. The remaining cuticle is fragmented. (H) shg2. Note holes in ventral epidermis. (I) Zygotic shg2 p120308. Note complete loss of ventral epidermis. (J) armYD35. Note shortened body and lawn of denticles ventrally (arrowhead), and defects in dorsal closure (arrow). (K and L) Zygotic armYD35 p120308 mutant that was also maternally p120308 mutant. Cuticles are longer, and in L dorsal closure defects are suppressed.
Mentions: In both situations, we saw genetic interactions consistent with p120 playing a positive role in modulating AJ function. Mutations in p120 strongly enhanced the phenotypes of shg mutants. Wild-type larvae are entirely enclosed in cuticle (Fig. 6 A). To make a proper cuticle, epithelial tissues must retain their integrity and morphogenetic movements such as head involution and dorsal closure must occur properly. Zygotic loss-of-function mutations in shg disrupt morphogenesis and epithelial integrity (Tepass et al., 1996; Uemura et al., 1996), with different processes differentially sensitive to the level of remaining DE-cad function (in all cases, maternal wild-type DE-cad remains, since without it oogenesis is disrupted, and thus this is the phenotype of DE-cad depletion, not its total absence). A weak allele (shgg119) primarily has defects in head involution such that the embryo secretes cuticle without head structures (Fig. 6 B). A stronger allele (shg2) has holes in the ventral cuticle (Fig. 6 H): ventral neurectoderm is more sensitive to reductions in DE-cad function due to stresses imposed by the ingression of neural cells (Tepass et al., 1996). Most zygotic mutants (shgR69) secrete only a sheet of dorsal cuticle (Fig. 6 E) due to disruption of the integrity of the ventral epidermis.

Bottom Line: We generated alleles of p120 and found that mutants are viable and fertile and have no substantial changes in junction structure or function.However, p120 mutations strongly enhance mutations in the genes encoding DE-cadherin or Armadillo, the beta-catenin homologue.Finally, we examined the localization of p120 during embryogenesis. p120 localizes to adherens junctions, but its localization there is less universal than that of core adherens junction proteins.

View Article: PubMed Central - PubMed

Affiliation: Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.

ABSTRACT
Cadherin-catenin complexes, localized to adherens junctions, are essential for cell-cell adhesion. One means of regulating adhesion is through the juxtamembrane domain of the cadherin cytoplasmic tail. This region is the binding site for p120, leading to the hypothesis that p120 is a key regulator of cell adhesion. p120 has also been suggested to regulate the GTPase Rho and to regulate transcription via its binding partner Kaiso. To test these hypothesized functions, we turned to Drosophila, which has only a single p120 family member. It localizes to adherens junctions and binds the juxtamembrane region of DE-cadherin (DE-cad). We generated alleles of p120 and found that mutants are viable and fertile and have no substantial changes in junction structure or function. However, p120 mutations strongly enhance mutations in the genes encoding DE-cadherin or Armadillo, the beta-catenin homologue. Finally, we examined the localization of p120 during embryogenesis. p120 localizes to adherens junctions, but its localization there is less universal than that of core adherens junction proteins. Together, these data suggest that p120 is an important positive modulator of adhesion but that it is not an essential core component of adherens junctions.

Show MeSH
Related in: MedlinePlus