title: Germ-line tumor formation caused by activation of glp-1, a Caenorhabditis elegans member of the Notch family of receptors.
abstract: Caenorhabditis elegans germ-line proliferation is controlled by an inductive interaction between the somatic distal tip cell and the germ line. GLP-1, a member of the Notch family of transmembrane receptors, is required continuously in the germ line to transduce the proliferative signal. In the absence of GLP-1, all proliferative germ cells exit the mitotic cell cycle and enter meiotic prophase. We have characterized an activating mutation in glp-1, oz112gf, that has the opposite phenotype. Homozygous glp-1(oz112gf) hermaphrodites and males have a completely tumorous germ line in which germ cells never leave the mitotic cycle. In glp-1(oz112gf) heterozygotes, germ-line polarity is established correctly, but as adults age, the distal proliferative population expands leading to a late-onset tumorous phenotype. The mutant receptor is constitutively active, promoting proliferation in the absence of ligand. The normal distal-proximal spatial restriction of GLP-1 expression is lost in tumorous and late-onset tumorous animals; ectopically proliferating germ cells contain membrane-associated GLP-1. The correlation between proliferation and expression, both in wild-type where glp-1 signalling is limited by localized ligand and in glp-1(oz112gf) where signalling is ligand-independent, suggests that glp-1 signalling positively regulates GLP-1 expression. In addition to germ-line defects, glp-1(oz112gf) causes inappropriate vulval cell fate specification. A missense mutation in a conserved extracellular residue, Ser642, adjacent to the transmembrane domain, is sufficient to confer the glp-1(oz112gf) mutant phenotypes. Two mammalian Notch family members, TAN-1 and int-3, are proto-oncogenes. Thus, activating mutations in both invertebrate and vertebrate Notch family members can lead to tumor formation.
authors.affiliation: Department of Genetics, Washington University School of Medicine, St Louis, MO 63110, USA.
authors.forename: L W
authors.initials: LW
authors.lastname: Berry
authors.forename: B
authors.initials: B
authors.lastname: Westlund
authors.forename: T
authors.initials: T
authors.lastname: Schedl
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins; D002454:Cell Differentiation; D002455:Cell Division; D012734:Disorders of Sex Development; D005260:Female; D005786:Gene Expression Regulation; D018014:Gene Transfer Techniques; D005854:Germ Cells / Q000166:cytology*; D018237:Germinoma / Q000235:genetics; D015801:Helminth Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008938:Mitosis; D009154:Mutation; D010641:Phenotype; D011956:Receptors, Cell Surface / Q000378:metabolism; D051880:Receptors, Notch
chemical_list: D029742:Caenorhabditis elegans Proteins; C060620:Glp-1 protein, C elegans; D015801:Helminth Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D051880:Receptors, Notch