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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 localizes to embryonic cell junctions but is not as uniformly distributed as core AJ proteins. (A–D) Stage 8. p120 (red); Arm (green). (Arrows) Cell junctions accumulating both p120 and Arm; (arrowheads) cell junctions depleted for p120. (E) Stage 9. p120 junctional accumulation is becoming more uniform. In mitotic cells, it is absent from the cytoplasm (arrows). (F–H) Stage 9. Histone-GFP (green); p120 (red); microtubules (MT; blue). (F and G) Apical planes; (H) section through the middle of the cells. In nonmitotic cells, p120 localizes in the cytoplasm and at cell junctions (F and G, red arrow). In mitotic cells, junctional and cytoplasmic p120 is reduced (E, arrows; F–H white arrows). Some junctional staining remains at the cell mid-plane (H, red arrow). (I) Stage 12/13. (J–N) Stage 14. p120 (red); Arm (green). (O) Stage 14. Live image, p120-GFP. (Arrows) Accumulation at the ends of stretched cells. Bars, 5 μm.
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fig9: p120 localizes to embryonic cell junctions but is not as uniformly distributed as core AJ proteins. (A–D) Stage 8. p120 (red); Arm (green). (Arrows) Cell junctions accumulating both p120 and Arm; (arrowheads) cell junctions depleted for p120. (E) Stage 9. p120 junctional accumulation is becoming more uniform. In mitotic cells, it is absent from the cytoplasm (arrows). (F–H) Stage 9. Histone-GFP (green); p120 (red); microtubules (MT; blue). (F and G) Apical planes; (H) section through the middle of the cells. In nonmitotic cells, p120 localizes in the cytoplasm and at cell junctions (F and G, red arrow). In mitotic cells, junctional and cytoplasmic p120 is reduced (E, arrows; F–H white arrows). Some junctional staining remains at the cell mid-plane (H, red arrow). (I) Stage 12/13. (J–N) Stage 14. p120 (red); Arm (green). (O) Stage 14. Live image, p120-GFP. (Arrows) Accumulation at the ends of stretched cells. Bars, 5 μm.

Mentions: During the extended germband stage, p120 begins to accumulate in epidermal cell junctions (Fig. 9), and it remains there through germband retraction. Although its localization roughly matches that of Arm, recruitment of p120 to junctions at several stages in development was less uniform. This was striking during germband elongation (Fig. 9, A–D). Arm outlined all ectodermal cells, regardless of the plane of focus (Fig. 9, A and C, green), reflecting the accumulation of Arm and DE-cad all along the lateral membrane (although they are enriched in AJs). In contrast, p120 was observed at cell junctions in a subset of cells (Fig. 9, B and D). This may reflect a more restricted localization of p120 along the lateral membrane, or it may suggest that strong recruitment of p120 to junctions lags behind that of Arm and DE-cad. As development proceeded, p120 localization to junctions became more uniform (Fig. 9, E and I, and Fig. 2, C and F). Interestingly, in mitotic cells the levels of cytoplasmic p120 drop sharply (Fig. 9, E–H). Differences in the localization of Arm and p120 reappeared during late dorsal closure when p120 was highly enriched in junctions of amnioserosa cells relative to those of the ectoderm, although Arm localized relatively uniformly (Fig. 9, J–N). p120-GFP, which is ubiquitously expressed from a heterologous promoter, does not show as striking a difference (Fig. 9 O).


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 localizes to embryonic cell junctions but is not as uniformly distributed as core AJ proteins. (A–D) Stage 8. p120 (red); Arm (green). (Arrows) Cell junctions accumulating both p120 and Arm; (arrowheads) cell junctions depleted for p120. (E) Stage 9. p120 junctional accumulation is becoming more uniform. In mitotic cells, it is absent from the cytoplasm (arrows). (F–H) Stage 9. Histone-GFP (green); p120 (red); microtubules (MT; blue). (F and G) Apical planes; (H) section through the middle of the cells. In nonmitotic cells, p120 localizes in the cytoplasm and at cell junctions (F and G, red arrow). In mitotic cells, junctional and cytoplasmic p120 is reduced (E, arrows; F–H white arrows). Some junctional staining remains at the cell mid-plane (H, red arrow). (I) Stage 12/13. (J–N) Stage 14. p120 (red); Arm (green). (O) Stage 14. Live image, p120-GFP. (Arrows) Accumulation at the ends of stretched cells. Bars, 5 μm.
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fig9: p120 localizes to embryonic cell junctions but is not as uniformly distributed as core AJ proteins. (A–D) Stage 8. p120 (red); Arm (green). (Arrows) Cell junctions accumulating both p120 and Arm; (arrowheads) cell junctions depleted for p120. (E) Stage 9. p120 junctional accumulation is becoming more uniform. In mitotic cells, it is absent from the cytoplasm (arrows). (F–H) Stage 9. Histone-GFP (green); p120 (red); microtubules (MT; blue). (F and G) Apical planes; (H) section through the middle of the cells. In nonmitotic cells, p120 localizes in the cytoplasm and at cell junctions (F and G, red arrow). In mitotic cells, junctional and cytoplasmic p120 is reduced (E, arrows; F–H white arrows). Some junctional staining remains at the cell mid-plane (H, red arrow). (I) Stage 12/13. (J–N) Stage 14. p120 (red); Arm (green). (O) Stage 14. Live image, p120-GFP. (Arrows) Accumulation at the ends of stretched cells. Bars, 5 μm.
Mentions: During the extended germband stage, p120 begins to accumulate in epidermal cell junctions (Fig. 9), and it remains there through germband retraction. Although its localization roughly matches that of Arm, recruitment of p120 to junctions at several stages in development was less uniform. This was striking during germband elongation (Fig. 9, A–D). Arm outlined all ectodermal cells, regardless of the plane of focus (Fig. 9, A and C, green), reflecting the accumulation of Arm and DE-cad all along the lateral membrane (although they are enriched in AJs). In contrast, p120 was observed at cell junctions in a subset of cells (Fig. 9, B and D). This may reflect a more restricted localization of p120 along the lateral membrane, or it may suggest that strong recruitment of p120 to junctions lags behind that of Arm and DE-cad. As development proceeded, p120 localization to junctions became more uniform (Fig. 9, E and I, and Fig. 2, C and F). Interestingly, in mitotic cells the levels of cytoplasmic p120 drop sharply (Fig. 9, E–H). Differences in the localization of Arm and p120 reappeared during late dorsal closure when p120 was highly enriched in junctions of amnioserosa cells relative to those of the ectoderm, although Arm localized relatively uniformly (Fig. 9, J–N). p120-GFP, which is ubiquitously expressed from a heterologous promoter, does not show as striking a difference (Fig. 9 O).

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