Signals transmitted along retinal axons in Drosophila: Hedgehog signal reception and the cell circuitry of lamina cartridge assembly.
The arrival of retinal axons in the brain of Drosophila triggers the assembly of glial and neuronal precursors into a 'neurocrystalline' array of lamina synaptic 'cartridges'. Hedgehog, a secreted protein, is an inductive signal delivered by retinal axons for the initial steps of lamina differentiation. In the development of many tissues, Hedgehog acts in a signal relay cascade via the induction of secondary secreted factors. Here we show that lamina neuronal precursors respond directly to Hedgehog signal reception by entering S-phase, a step that is controlled by the Hedgehog-dependent transcriptional regulator Cubitus interruptus. The terminal differentiation of neuronal precursors and the migration and differentiation of glia appear to be controlled by other retinal axon-mediated signals. Thus retinal axons impose a program of developmental events on their postsynaptic field utilizing distinct signals for different precursor populations.
Huang
Z
Z
Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
Kunes
S
S
D000818:Animals; D030801:Animals, Genetically Modified; D001369:Axons / Q000502:physiology; D002453:Cell Cycle; D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D004330:Drosophila / Q000235:genetics / Q000254:growth & development* / Q000502:physiology*; D029721:Drosophila Proteins; D015870:Gene Expression; D017344:Genes, Insect; D053823:Hedgehog Proteins; D007150:Immunohistochemistry; D019476:Insect Proteins / Q000235:genetics / Q000502:physiology*; D007814:Larva / Q000254:growth & development / Q000502:physiology; D018613:Microscopy, Confocal; D009457:Neuroglia / Q000166:cytology / Q000502:physiology; D017956:Photoreceptor Cells, Invertebrate / Q000254:growth & development / Q000502:physiology; D011956:Receptors, Cell Surface / Q000235:genetics / Q000502:physiology; D043562:Receptors, G-Protein-Coupled; D012160:Retina / Q000166:cytology / Q000254:growth & development / Q000502:physiology*; D015398:Signal Transduction; D000072086:Smoothened Receptor; D013477:Superior Colliculi / Q000166:cytology / Q000254:growth & development / Q000502:physiology; D014157:Transcription Factors; D014795:Visual Pathways / Q000166:cytology / Q000254:growth & development / Q000502:physiology
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D053823:Hedgehog Proteins; D019476:Insect Proteins; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D000072086:Smoothened Receptor; D014157:Transcription Factors; C092937:ci protein, Drosophila; C100664:smo protein, Drosophila; C077245:hh protein, Drosophila