Regulation of Wingless and Vestigial expression in wing and haltere discs of Drosophila.
In the third thoracic segment of Drosophila, wing development is suppressed by the homeotic selector gene Ultrabithorax (Ubx) in order to mediate haltere development. Previously, we have shown that Ubx represses dorsoventral (DV) signaling to specify haltere fate. Here we examine the mechanism of Ubx-mediated downregulation of DV signaling. We show that Wingless (Wg) and Vestigial (Vg) are differentially regulated in wing and haltere discs. In wing discs, although Vg expression in non-DV cells is dependent on DV boundary function of Wg, it maintains its expression by autoregulation. Thus, overexpression of Vg in non-DV cells can bypass the requirement for Wg signaling from the DV boundary. Ubx functions, at least, at two levels to repress Vestigial expression in non-DV cells of haltere discs. At the DV boundary, it functions downstream of Shaggy/GSK3 beta to enhance the degradation of Armadillo (Arm), which causes downregulation of Wg signaling. In non-DV cells, Ubx inhibits event(s) downstream of Arm, but upstream of Vg autoregulation. Repression of Vg at multiple levels appears to be crucial for Ubx-mediated specification of the haltere fate. Overexpression of Vg in haltere discs is enough to override Ubx function and cause haltere-to-wing homeotic transformations.
Prasad
Mohit
M
Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500 007, India.
Bajpai
Ruchi
R
Shashidhara
L S
LS
D000818:Animals; D051186:Armadillo Domain Proteins; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000254:growth & development* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D018398:Homeodomain Proteins; D009024:Morphogenesis / Q000502:physiology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014921:Wings, Animal / Q000033:anatomy & histology / Q000254:growth & development* / Q000378:metabolism; D051155:Wnt1 Protein
C495305:ARM protein, Drosophila; D051186:Armadillo Domain Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C066177:Ubx protein, Drosophila; D051155:Wnt1 Protein; C095064:vg protein, Drosophila; C074622:wg protein, Drosophila; C080335:Sgg protein, Drosophila; D038362:Glycogen Synthase Kinase 3