Loss of the beta-catenin homologue aardvark causes ectopic stalk formation in Dictyostelium.
Aardvark (Aar) is a Dictyostelium beta-catenin homologue with both cytoskeletal and signal transduction roles during development. Here, we show that loss of aar causes a novel phenotype where multiple stalks appear during late development. Ectopic stalks are preceded by misexpression of the stalk marker ST-lacZ in the surrounding tissue. This process does not involve the kinase GSK-3. Mixing experiments show that ectopic ST-lacZ expression and stalk formation are cell non-autonomous. The protein-cellulose matrix surrounding the stalk of aar mutant fruiting bodies is defective, and damage to the stalk of wild-type fruiting bodies leads to ectopic ST-lacZ expression. We postulate that poor synthesis of the stalk tube matrix allows diffusion of a stalk cell-inducing factor into the surrounding tissue.
MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, UK. jcc44@cam.ac.uk
Juliet C
JC
Coates
Mark J
MJ
Grimson
Robin S B
RS
Williams
Wayland
W
Bergman
Richard L
RL
Blanton
Adrian J
AJ
Harwood
D000818:Animals; D030801:Animals, Genetically Modified; D003598:Cytoskeletal Proteins / Q000172:deficiency / Q000235:genetics* / Q000502:physiology; D004023:Dictyostelium / Q000235:genetics* / Q000254:growth & development* / Q000502:physiology; D016326:Extracellular Matrix Proteins / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D017125:Genes, Protozoan; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics / Q000378:metabolism; D038341:Glycogen Synthase Kinases / Q000235:genetics; D007763:Lac Operon; D009154:Mutation; D010641:Phenotype; D015800:Protozoan Proteins / Q000235:genetics; D015398:Signal Transduction; D015534:Trans-Activators / Q000172:deficiency / Q000235:genetics* / Q000502:physiology; D051176:beta Catenin
D003598:Cytoskeletal Proteins; D016326:Extracellular Matrix Proteins; D015800:Protozoan Proteins; D015534:Trans-Activators; D051176:beta Catenin; C069214:ecmB protein, Dictyostelium; D038341:Glycogen Synthase Kinases; D038362:Glycogen Synthase Kinase 3