title: Genetic characterization of ebi reveals its critical role in Drosophila wing growth.
abstract: The ebi gene of Drosophila melanogaster has been implicated in diverse signalling pathways, cellular functions and developmental processes. However, a thorough genetic analysis of this gene has been lacking and the true extent of its biological roles is unclear. Here, we characterize eleven ebi mutations and find that ebi has a novel role in promoting growth of the wing imaginal disc: viable combinations of mutant alleles give rise to adults with small wings. Wing discs with reduced EBI levels are correspondingly small and exhibit down-regulation of Notch target genes. Furthermore, we show that EBI colocalizes on polytene chromosomes with Smrter (SMR), a transcriptional corepressor, and Suppressor of Hairless (SU(H)), the primary transcription factor involved in Notch signalling. Interestingly, the mammalian orthologs of ebi, transducin β-like 1 (TBL1) and TBL-related 1 (TBLR1), function as corepressor/coactivator exchange factors and are required for transcriptional activation of Notch target genes. We hypothesize that EBI acts to activate (de-repress) transcription of Notch target genes important for Drosophila wing growth by functioning as a corepressor/coactivator exchange factor for SU(H).
authors: University of Cambridge, Cambridge, UK. sjm41@gen.cam.ac.uk
authors: Steven J
authors: SJ
authors: Marygold
authors: Cherryl
authors: C
authors: Walker
authors: Mariam
authors: M
authors: Orme
authors: Sally
authors: S
authors: Leevers
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D056970:Co-Repressor Proteins / Q000032:analysis / Q000378:metabolism; D029721:Drosophila Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D059007:Polytene Chromosomes / Q000378:metabolism; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000032:analysis / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014921:Wings, Animal / Q000033:anatomy & histology / Q000254:growth & development* / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D056970:Co-Repressor Proteins; D029721:Drosophila Proteins; C497759:N protein, Drosophila; D009687:Nuclear Proteins; D051880:Receptors, Notch; D012097:Repressor Proteins; C121508:Smr protein, Drosophila; C088731:Su(H) protein, Drosophila; D014157:Transcription Factors; C119014:ebi protein, Drosophila; C087984:sd protein, Drosophila; C095064:vg protein, Drosophila; D019204:GTP-Binding Proteins