Epithelial polarity and cell separation in the neoplastic l(1)dlg-1 mutant of Drosophila.
Lethal (1) discs-large-1 [l(1)dlg-1] is a non-epithelial overgrowth or neoplastic mutant of Drosophila, which results in tumor-like imaginal discs and enlarged larvae that never pupariate. In an ultrastructural analysis we found that the wing discs develop convoluted monolayers of epithelial cells characterized by well-defined apical-basal polarity and that these layered cells secrete large amounts of basement membrane material. Immuno-EM indicates that Drosophila laminin and collagen are components of this matrix. Late in development clusters or 'rosettes' of separated cells lacking cell-cell junctions and apical-basal polarity form. In in vitro culture experiments l(1)dlg-1 wing discs did not respond to a pulse of exogenous ecdysone by secreting cuticle or losing basement membrane as normal discs do. Our observations are consistent with the hypothesis that cell-cell interaction and communication is required for termination of disc cell proliferation, which must occur prior to a cellular response to ecdysone.
Abbott
L A
LA
Zoology Department, University of California-Davis.
Natzle
J E
JE
D000818:Animals; D001485:Basement Membrane / Q000378:metabolism; D002450:Cell Communication / Q000235:genetics; D016923:Cell Death / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D016764:Cell Polarity / Q000235:genetics*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics*; D004440:Ecdysone / Q000494:pharmacology; D004848:Epithelium / Q000473:pathology; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis; D005804:Genes, Lethal; D007301:Insect Hormones / Q000235:genetics / Q000502:physiology*; D007814:Larva; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D009363:Neoplasm Proteins / Q000096:biosynthesis; D009374:Neoplasms, Experimental / Q000196:embryology* / Q000378:metabolism; D010641:Phenotype; D025521:Tumor Suppressor Proteins; D014921:Wings, Animal / Q000196:embryology*
D029721:Drosophila Proteins; D016326:Extracellular Matrix Proteins; D007301:Insect Hormones; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D025521:Tumor Suppressor Proteins; C070350:dlg1 protein, Drosophila; D004440:Ecdysone