title: Contributions of extracellular and intracellular domains of full length and chimeric cadherin molecules to junction assembly in epithelial cells.
abstract: The integrity of cell-cell junctions in epithelial cells depends on functional interactions of both extracellular and intracellular domains of cadherins with other junction proteins. To examine the roles of the different domains of E-cadherin and desmoglein in epithelial junctions, we stably expressed full length desmoglein 1 and chimeras of E-cadherin and desmoglein 1 in A431 epithelial cells. Full length desmoglein 1 was able to incorporate into or disrupt endogenous desmosomes depending on expression level. Each of the chimeric cadherin molecules exhibited distinct localization patterns at the cell surface. A chimera of the desmoglein 1 extracellular domain and the E-cadherin intracellular domain was distributed diffusely at the cell surface while the reverse chimera, comprising the E-cadherin extracellular domain and the desmoglein 1 intracellular domain, localized in large, sometimes contiguous patches at cell-cell interfaces. Nevertheless, both constructs disrupted desmosome assembly. Expression of constructs containing the desmoglein 1 cytoplasmic domain resulted in approximately a 3-fold decrease in E-cadherin bound to plakoglobin and a 5- to 10-fold reduction in the steady-state levels of the endogenous desmosomal cadherins, desmoglein 2 and desmocollin 2, possibly contributing to the dominant negative effect of the desmoglein 1 tail. In addition, biochemical analysis of protein complexes in the stable lines revealed novel in vivo protein interactions. Complexes containing beta-catenin and desmoglein 1 were identified in cells expressing constructs containing the desmoglein 1 tail. Furthermore, interactions were identified between endogenous E-cadherin and the chimera containing the E-cadherin extracellular domain and the desmoglein 1 intracellular domain providing in vivo evidence for previously predicted lateral interactions of E-cadherin extracellular domains.
authors.affiliation: Department of Pathology, Northwestern University Medical School, Chicago, IL 60611, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Norvell
authors.forename: K J
authors.initials: KJ
authors.lastname: Green
mesh_terms: D015820:Cadherins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000473:pathology; D003598:Cytoskeletal Proteins / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D051187:Desmocollins; D051183:Desmoglein 1; D051301:Desmoglein 2; D051182:Desmogleins; D051180:Desmoplakins; D003896:Desmosomes / Q000737:chemistry* / Q000648:ultrastructure; D046911:Macromolecular Substances; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D012995:Solubility; D013329:Structure-Activity Relationship; D014162:Transfection; D014407:Tumor Cells, Cultured; D051185:gamma Catenin
chemical_list: D015820:Cadherins; D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; D051187:Desmocollins; D051183:Desmoglein 1; D051301:Desmoglein 2; D051182:Desmogleins; D051180:Desmoplakins; D046911:Macromolecular Substances; D011993:Recombinant Fusion Proteins; D051185:gamma Catenin