title: Armadillo levels are reduced during mitosis in Drosophila.
abstract: The Armadillo protein of Drosophila melanogaster is both a structural component of adherens junctions at apical cell membranes and also a key cytoplasmic transducer of the Wingless signalling pathway. We have used the Gal4-UAS system to over-express Armadillo in the Drosophila wing: this hyperactivates the Wingless pathway and leads to the formation of ectopic, supernumerary wing bristles. Here, we report that this adult phenotype is dominantly enhanced by mutations in cdc25(string) and, conversely, is suppressed by co-expression of Cdc25(String). Furthermore, we show that the steady state levels of Armadillo protein produced from the UAS transgene are also sensitive to cdc25(string) dosage in the cells of the larval imaginal wing disc. Consistent with the role of Cdc25(String) in promoting mitosis and with our genetic interaction data, we find a strong correlation between progression through mitosis and a reduction in Armadillo levels. Significantly, this is true whether Armadillo is over-expressed or not, and both cytoplasmic (signalling) and membrane-associated (junctional) Armadillo appears to be affected. We conclude that this phenomenon may reduce the efficacy of Wingless signalling and/or intercellular adhesion during cell division.
authors.affiliation: MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK. steven.marygold@cancer.org.uk
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Marygold
authors.forename: Jean Paul
authors.initials: JP
authors.lastname: Vincent
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D051186:Armadillo Domain Proteins; D019521:Body Patterning / Q000235:genetics; D002448:Cell Adhesion / Q000235:genetics; D018797:Cell Cycle Proteins; D003593:Cytoplasm / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics*; D018628:Gene Dosage; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D007814:Larva; D008938:Mitosis; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D017027:Protein Tyrosine Phosphatases; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014921:Wings, Animal / Q000002:abnormalities / Q000254:growth & development / Q000378:metabolism; D051155:Wnt1 Protein
chemical_list: C495305:ARM protein, Drosophila; D051186:Armadillo Domain Proteins; D018797:Cell Cycle Proteins; D029721:Drosophila Proteins; C063459:En protein, Drosophila; D018398:Homeodomain Proteins; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D051155:Wnt1 Protein; C074622:wg protein, Drosophila; D010749:Phosphoprotein Phosphatases; D017027:Protein Tyrosine Phosphatases; C059217:stg protein, Drosophila