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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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Drosophila p120 is a member of the p120 subfamily. (A) Gene structure of p120 and the two adjacent genes, LD05623 and CG17486. KG01086, the P element insertion used to generate p120 mutants, is indicated, as is the region deleted in p120308 (uncertainty in the left boundary is indicated as a dotted line). (B) Human, fly, and mosquito p120. Gray boxes represent Arm repeats. Repeat 6, which diverges from the consensus, is indicated by a “?”. Loops represent conserved inserts in Arm repeats. Hatched box shows conserved region of similarity. Amino acid identities in pairwise comparisons of the regions bracketed are indicated. (C) Unrooted tree of the p120 subfamily, plakophilin subfamily, and selected other Arm repeat proteins. H, human; M, mouse; X, Xenopus.
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fig1: Drosophila p120 is a member of the p120 subfamily. (A) Gene structure of p120 and the two adjacent genes, LD05623 and CG17486. KG01086, the P element insertion used to generate p120 mutants, is indicated, as is the region deleted in p120308 (uncertainty in the left boundary is indicated as a dotted line). (B) Human, fly, and mosquito p120. Gray boxes represent Arm repeats. Repeat 6, which diverges from the consensus, is indicated by a “?”. Loops represent conserved inserts in Arm repeats. Hatched box shows conserved region of similarity. Amino acid identities in pairwise comparisons of the regions bracketed are indicated. (C) Unrooted tree of the p120 subfamily, plakophilin subfamily, and selected other Arm repeat proteins. H, human; M, mouse; X, Xenopus.

Mentions: We searched for p120 homologues in a fly cDNA library using degenerate PCR with primers to regions conserved in vertebrate p120s. One primer pair gave a product of the expected size (see Materials and methods) that encoded an ORF with similarity to human p120. This was used to probe a cDNA library. From 20 positive clones (all derived from a single gene) a full-length coding sequence was assembled (sequence data available from GenBank/EMBL/DDBJ under accession no. AF220496). This was subsequently confirmed by sequencing of two full-length cDNAs by the Berkeley Drosophila Genome Project (BDGP; information was obtained from http://www.fruitfly.org). A single conservative change (I357V) in the coding sequence was observed among the three sequences. We mapped the p120 gene to band 41C near the heterochromatin of the right arm of chromosome 2 by hybridization to a genomic P1 blot and in situ hybridization to polytene chromosomes (unpublished data). This was subsequently confirmed by the BDGP/Celera sequencing project (http://www.fruitfly.org). p120 includes four exons spanning ∼14 kb (Fig. 1 A). BDGP's gene prediction programs predict slightly different splice junctions and include a fifth exon, but these predictions are not borne out by our or the BDGP cDNAs.


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)

Drosophila p120 is a member of the p120 subfamily. (A) Gene structure of p120 and the two adjacent genes, LD05623 and CG17486. KG01086, the P element insertion used to generate p120 mutants, is indicated, as is the region deleted in p120308 (uncertainty in the left boundary is indicated as a dotted line). (B) Human, fly, and mosquito p120. Gray boxes represent Arm repeats. Repeat 6, which diverges from the consensus, is indicated by a “?”. Loops represent conserved inserts in Arm repeats. Hatched box shows conserved region of similarity. Amino acid identities in pairwise comparisons of the regions bracketed are indicated. (C) Unrooted tree of the p120 subfamily, plakophilin subfamily, and selected other Arm repeat proteins. H, human; M, mouse; X, Xenopus.
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getmorefigures.php?uid=PMC2172674&req=5

fig1: Drosophila p120 is a member of the p120 subfamily. (A) Gene structure of p120 and the two adjacent genes, LD05623 and CG17486. KG01086, the P element insertion used to generate p120 mutants, is indicated, as is the region deleted in p120308 (uncertainty in the left boundary is indicated as a dotted line). (B) Human, fly, and mosquito p120. Gray boxes represent Arm repeats. Repeat 6, which diverges from the consensus, is indicated by a “?”. Loops represent conserved inserts in Arm repeats. Hatched box shows conserved region of similarity. Amino acid identities in pairwise comparisons of the regions bracketed are indicated. (C) Unrooted tree of the p120 subfamily, plakophilin subfamily, and selected other Arm repeat proteins. H, human; M, mouse; X, Xenopus.
Mentions: We searched for p120 homologues in a fly cDNA library using degenerate PCR with primers to regions conserved in vertebrate p120s. One primer pair gave a product of the expected size (see Materials and methods) that encoded an ORF with similarity to human p120. This was used to probe a cDNA library. From 20 positive clones (all derived from a single gene) a full-length coding sequence was assembled (sequence data available from GenBank/EMBL/DDBJ under accession no. AF220496). This was subsequently confirmed by sequencing of two full-length cDNAs by the Berkeley Drosophila Genome Project (BDGP; information was obtained from http://www.fruitfly.org). A single conservative change (I357V) in the coding sequence was observed among the three sequences. We mapped the p120 gene to band 41C near the heterochromatin of the right arm of chromosome 2 by hybridization to a genomic P1 blot and in situ hybridization to polytene chromosomes (unpublished data). This was subsequently confirmed by the BDGP/Celera sequencing project (http://www.fruitfly.org). p120 includes four exons spanning ∼14 kb (Fig. 1 A). BDGP's gene prediction programs predict slightly different splice junctions and include a fifth exon, but these predictions are not borne out by our or the BDGP cDNAs.

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