Signaling and adhesion activities of mammalian beta-catenin and plakoglobin in Drosophila.
The armadillo protein of Drosophila and its vertebrate homologues, beta-catenin and plakoglobin, are implicated in cell adhesion and wnt signaling. Here, we examine the conservation of these two functions by assaying the activities of mammalian beta-catenin and plakoglobin in Drosophila. We show that, in the female germ line, both mammalian beta-catenin and plakoglobin complement an armadillo mutation. We also show that shotgun mutant germ cells (which lack Drosophila E-cadherin) have a phenotype identical to that of armadillo mutant germ cells. It therefore appears that armadillo's role in the germ line is solely in a complex with Drosophila E-cadherin (possibly an adhesion complex), and both beta-catenin and plakoglobin can function in Drosophila cadherin complexes. In embryonic signaling assays, we find that plakoglobin has no detectable activity whereas beta-catenin's activity is weak. Surprisingly, when overexpressed, either in embryos or in wing imaginal disks, both beta-catenin and plakoglobin have dominant negative activity on signaling, an effect also obtained with COOH-terminally truncated armadillo. We suggest that the signaling complex, which has been shown by others to comprise armadillo and a member of the lymphocyte enhancer binding factor-1/T cell factor-family, may contain an additional factor that normally binds to the COOH-terminal region of armadillo.
White
P
P
Medical Research Council, Laboratory of Molecular Biology, Cambridge CB2 2QH, United Kingdom.
Aberle
H
H
Vincent
J P
JP
D000818:Animals; D051186:Armadillo Domain Proteins; D015820:Cadherins / Q000378:metabolism; D002448:Cell Adhesion; D003433:Crosses, Genetic; D003598:Cytoskeletal Proteins / Q000096:biosynthesis / Q000378:metabolism*; D051180:Desmoplakins; D004330:Drosophila / Q000235:genetics / Q000502:physiology*; D029721:Drosophila Proteins; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000502:physiology; D005260:Female; D006720:Homozygote; D019476:Insect Proteins / Q000096:biosynthesis / Q000235:genetics; D008297:Male; D008322:Mammals; D015398:Signal Transduction; D015534:Trans-Activators; D014157:Transcription Factors; D014921:Wings, Animal; D051176:beta Catenin; D051185:gamma Catenin
C495305:ARM protein, Drosophila; D051186:Armadillo Domain Proteins; D015820:Cadherins; D003598:Cytoskeletal Proteins; D051180:Desmoplakins; D029721:Drosophila Proteins; D019476:Insect Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D051176:beta Catenin; D051185:gamma Catenin