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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 colocalizes with Arm in other tissues. (A–D) Stage 15. p120 (red); Arm (green). Arm is enriched in fusion cells (red arrows). (E) p120-GFP. (F and G) Stage 15–16. p120 (red) and Arm (green) colocalize to peripheral nervous system chordotonal organs. (F and G, insets) Similar stage p120 mutant. Arm localizes to chordotonals; p120 is lost. (H) p120-GFP in chordotonals. (I–K) Stage 17. p120 (red); Arm (green). (L) p120-GFP. (M–N) p120-GFP. (M) Eye imaginal disc. Undifferentiated cells (arrowheads), photoreceptor cells (arrows). (N and O) Larval brain. (N) p120-GFP at cell borders between neuroblasts (arrowheads) and ganglion mother cells (arrow). (O) Progeny of neuroblasts (arrowheads) sending bundled axons (arrows) to the neuropil. (P) Stage 10 egg chamber. p120-GFP (green) and Arm (red) colocalize at cell junctions of migrating border cells (arrow). In nurse cells, p120-GFP is cytoplasmic but excluded from nuclei (arrowhead). Bars, 5 μm.
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fig10: p120 colocalizes with Arm in other tissues. (A–D) Stage 15. p120 (red); Arm (green). Arm is enriched in fusion cells (red arrows). (E) p120-GFP. (F and G) Stage 15–16. p120 (red) and Arm (green) colocalize to peripheral nervous system chordotonal organs. (F and G, insets) Similar stage p120 mutant. Arm localizes to chordotonals; p120 is lost. (H) p120-GFP in chordotonals. (I–K) Stage 17. p120 (red); Arm (green). (L) p120-GFP. (M–N) p120-GFP. (M) Eye imaginal disc. Undifferentiated cells (arrowheads), photoreceptor cells (arrows). (N and O) Larval brain. (N) p120-GFP at cell borders between neuroblasts (arrowheads) and ganglion mother cells (arrow). (O) Progeny of neuroblasts (arrowheads) sending bundled axons (arrows) to the neuropil. (P) Stage 10 egg chamber. p120-GFP (green) and Arm (red) colocalize at cell junctions of migrating border cells (arrow). In nurse cells, p120-GFP is cytoplasmic but excluded from nuclei (arrowhead). Bars, 5 μm.

Mentions: p120 is also enriched in other tissues where AJ proteins are enriched. p120 accumulates at high levels in trachea (Fig. 10, A–D). Arm and DE-cad accumulate at especially high levels in fusion cells, where tracheal elements that invaginated from different segments join (Uemura et al., 1996) (Fig. 10, B–D, arrows). p120 is not strikingly enriched there (although p120-GFP is) (Fig. 10 E). In the nervous system, both p120 and p120GFP accumulate in axons (Fig. 10, I–L) and in sensory structures of the peripheral nervous sytem (Fig. 10, F–H). Relative enrichment of p120 in the CNS versus the epidermis did not appear as high as that of Arm; this may be real, but the high levels of p120 mRNA in the CNS (Fig. 7 F) suggest that it may be due to differences in penetration of anti-p120 and anti-Arm antibodies. We also used p120-GFP to examine its subcellular localization in select postembryonic tissues. In eye imaginal discs, p120-GFP accumulates uniformly at cell–cell boundaries of undifferentiated cells ahead of the morphogenetic furrow (Fig. 10 M, arrowheads), and at elevated levels where differentiating photoreceptors abut one another (Fig. 10 M, arrows), resembling Arm. In larval brains, p120-GFP localizes to cell boundaries between neuroblasts and ganglion mother cells (Fig. 10 N) and to axon bundles emerging from the neuroblast's progeny (Fig. 10 O), paralleling AJ proteins (Akong et al., 2002). In ovaries, p120-GFP colocalizes with Arm in AJs of epithelial follicle cells (Fig. 2 P and Fig. 10 P), junctions between migrating border cells (Fig. 10 P, arrow) and, more weakly, in junctions between germ cells.


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 colocalizes with Arm in other tissues. (A–D) Stage 15. p120 (red); Arm (green). Arm is enriched in fusion cells (red arrows). (E) p120-GFP. (F and G) Stage 15–16. p120 (red) and Arm (green) colocalize to peripheral nervous system chordotonal organs. (F and G, insets) Similar stage p120 mutant. Arm localizes to chordotonals; p120 is lost. (H) p120-GFP in chordotonals. (I–K) Stage 17. p120 (red); Arm (green). (L) p120-GFP. (M–N) p120-GFP. (M) Eye imaginal disc. Undifferentiated cells (arrowheads), photoreceptor cells (arrows). (N and O) Larval brain. (N) p120-GFP at cell borders between neuroblasts (arrowheads) and ganglion mother cells (arrow). (O) Progeny of neuroblasts (arrowheads) sending bundled axons (arrows) to the neuropil. (P) Stage 10 egg chamber. p120-GFP (green) and Arm (red) colocalize at cell junctions of migrating border cells (arrow). In nurse cells, p120-GFP is cytoplasmic but excluded from nuclei (arrowhead). Bars, 5 μm.
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fig10: p120 colocalizes with Arm in other tissues. (A–D) Stage 15. p120 (red); Arm (green). Arm is enriched in fusion cells (red arrows). (E) p120-GFP. (F and G) Stage 15–16. p120 (red) and Arm (green) colocalize to peripheral nervous system chordotonal organs. (F and G, insets) Similar stage p120 mutant. Arm localizes to chordotonals; p120 is lost. (H) p120-GFP in chordotonals. (I–K) Stage 17. p120 (red); Arm (green). (L) p120-GFP. (M–N) p120-GFP. (M) Eye imaginal disc. Undifferentiated cells (arrowheads), photoreceptor cells (arrows). (N and O) Larval brain. (N) p120-GFP at cell borders between neuroblasts (arrowheads) and ganglion mother cells (arrow). (O) Progeny of neuroblasts (arrowheads) sending bundled axons (arrows) to the neuropil. (P) Stage 10 egg chamber. p120-GFP (green) and Arm (red) colocalize at cell junctions of migrating border cells (arrow). In nurse cells, p120-GFP is cytoplasmic but excluded from nuclei (arrowhead). Bars, 5 μm.
Mentions: p120 is also enriched in other tissues where AJ proteins are enriched. p120 accumulates at high levels in trachea (Fig. 10, A–D). Arm and DE-cad accumulate at especially high levels in fusion cells, where tracheal elements that invaginated from different segments join (Uemura et al., 1996) (Fig. 10, B–D, arrows). p120 is not strikingly enriched there (although p120-GFP is) (Fig. 10 E). In the nervous system, both p120 and p120GFP accumulate in axons (Fig. 10, I–L) and in sensory structures of the peripheral nervous sytem (Fig. 10, F–H). Relative enrichment of p120 in the CNS versus the epidermis did not appear as high as that of Arm; this may be real, but the high levels of p120 mRNA in the CNS (Fig. 7 F) suggest that it may be due to differences in penetration of anti-p120 and anti-Arm antibodies. We also used p120-GFP to examine its subcellular localization in select postembryonic tissues. In eye imaginal discs, p120-GFP accumulates uniformly at cell–cell boundaries of undifferentiated cells ahead of the morphogenetic furrow (Fig. 10 M, arrowheads), and at elevated levels where differentiating photoreceptors abut one another (Fig. 10 M, arrows), resembling Arm. In larval brains, p120-GFP localizes to cell boundaries between neuroblasts and ganglion mother cells (Fig. 10 N) and to axon bundles emerging from the neuroblast's progeny (Fig. 10 O), paralleling AJ proteins (Akong et al., 2002). In ovaries, p120-GFP colocalizes with Arm in AJs of epithelial follicle cells (Fig. 2 P and Fig. 10 P), junctions between migrating border cells (Fig. 10 P, arrow) and, more weakly, in junctions between germ cells.

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