Growth and cell survival are unevenly impaired in pixie mutant wing discs.
It is largely unknown how growth slows and then stops in vivo. Similar to most organs, Drosophila imaginal discs undergo a fast, near-exponential growth phase followed by a slow growth phase before final target size is reached. We have used a genetic approach to study the role of an ABC-E protein, Pixie, in wing disc growth. pixie mutants, like mutants in ribosomal proteins genes (known as Minutes), show severe developmental delay with relatively mild alterations in final body size. Intriguingly, pixie mutant wing imaginal discs show complex regional and temporal defects in growth and cell survival that are compensated to result in near-normal final size. In S2 cells, Pixie, like its yeast homolog RLI1, is required for translation. However, a comparison of the growth of eukaryotic translation initiation factor eIF4A and pixie mutant clones in wing discs suggests that only a subset of translation regulators, including pixie, mediate regional differences in growth and cell survival in wing discs. Interestingly, some of the regional effects on pixie mutant clone growth are enhanced in a Minute background. Our results suggest that the role of Pixie is not merely to allow growth, as might be expected for a translation regulator. Instead, Pixie also behaves as a target of putative constraining signals that slow disc growth during late larval life. We propose a model in which a balance of growth inhibitors and promoters determines tissue growth rates and cell survival. An alteration in this balance slows growth before final disc size is reached.
Coelho
Carmen M A
CM
Cancer Research UK London Research Institute, PO Box 123, 44 Lincolns Inn Fields, London WC2A 3PX, UK.
Kolevski
Benjamin
B
Bunn
Caroline
C
Walker
Cherryl
C
Dahanukar
Anupama
A
Leevers
Sally J
SJ
D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000502:physiology*; D000818:Animals; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D004330:Drosophila / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029721:Drosophila Proteins / Q000235:genetics / Q000502:physiology*; D039601:Eukaryotic Initiation Factor-4A / Q000235:genetics / Q000502:physiology; D007814:Larva / Q000254:growth & development / Q000502:physiology; D009154:Mutation; D014176:Protein Biosynthesis; D015398:Signal Transduction; D014921:Wings, Animal / Q000254:growth & development / Q000502:physiology
D018528:ATP-Binding Cassette Transporters; D029721:Drosophila Proteins; C521107:pix protein, drosophila; D039601:Eukaryotic Initiation Factor-4A