title: Mechanism of hedgehog signaling during Drosophila eye development.
abstract: Although Hedgehog (Hh) signaling is essential for morphogenesis of the Drosophila eye, its exact link to the network of tissue-specific genes that regulate retinal determination has remained elusive. In this report, we demonstrate that the retinal determination gene eyes absent (eya) is the crucial link between the Hedgehog signaling pathway and photoreceptor differentiation. Specifically, we show that the mechanism by which Hh signaling controls initiation of photoreceptor differentiation is to alleviate repression of eya and decapentaplegic (dpp) expression by the zinc-finger transcription factor Cubitus interruptus (Ci(rep)). Furthermore, our results suggest that stabilized, full length Ci (Ci(act)) plays little or no role in Drosophila eye development. Moreover, while the effects of Hh are primarily concentration dependent in other tissues, hh signaling in the eye acts as a binary switch to initiate retinal morphogenesis by inducing expression of the tissue-specific factor Eya.
authors.affiliation: Program in Developmental Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
authors.forename: Kartik S
authors.initials: KS
authors.lastname: Pappu
authors.forename: Rui
authors.initials: R
authors.lastname: Chen
authors.forename: Brooke W
authors.initials: BW
authors.lastname: Middlebrooks
authors.forename: Catherine
authors.initials: C
authors.lastname: Woo
authors.forename: Ulrike
authors.initials: U
authors.lastname: Heberlein
authors.forename: Graeme
authors.initials: G
authors.lastname: Mardon
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000196:embryology* / Q000254:growth & development / Q000502:physiology; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D053823:Hedgehog Proteins; D008954:Models, Biological; D009024:Morphogenesis / Q000502:physiology*; D030781:Organisms, Genetically Modified; D017956:Photoreceptor Cells, Invertebrate / Q000166:cytology / Q000196:embryology* / Q000254:growth & development / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D014157:Transcription Factors; D014921:Wings, Animal / Q000033:anatomy & histology / Q000196:embryology / Q000254:growth & development
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D005136:Eye Proteins; D053823:Hedgehog Proteins; D014157:Transcription Factors; C092937:ci protein, Drosophila; C064196:dpp protein, Drosophila; C092694:eya protein, Drosophila; C077245:hh protein, Drosophila