10779/crick.12497969.v1 Holger Apitz Holger Apitz Iris Salecker Iris Salecker Spatio-temporal relays control layer identity of direction-selective neuron subtypes in Drosophila The Francis Crick Institute 2020 Alleles Animals Axons Drosophila Proteins Drosophila melanogaster Female Gene Expression Regulation, Developmental Male Motion Perception Nerve Tissue Proteins Neurons Nuclear Proteins Protein Domains RNA Interference Signal Transduction T-Box Domain Proteins Vision, Ocular Wings, Animal Wnt1 Protein Salecker FC001151 2020-06-25 15:16:20 Journal contribution https://crick.figshare.com/articles/journal_contribution/Spatio-temporal_relays_control_layer_identity_of_direction-selective_neuron_subtypes_in_Drosophila/12497969 Visual motion detection in sighted animals is essential to guide behavioral actions ensuring their survival. In Drosophila, motion direction is first detected by T4/T5 neurons. Their axons innervate one of the four lobula plate layers. How T4/T5 neurons with layer-specific representation of motion-direction preferences are specified during development is unknown. We show that diffusible Wingless (Wg) between adjacent neuroepithelia induces its own expression to form secondary signaling centers. These activate Decapentaplegic (Dpp) signaling in adjacent lateral tertiary neuroepithelial domains dedicated to producing layer 3/4-specific T4/T5 neurons. T4/T5 neurons derived from the core domain devoid of Dpp signaling adopt the default layer 1/2 fate. Dpp signaling induces the expression of the T-box transcription factor Optomotor-blind (Omb), serving as a relay to postmitotic neurons. Omb-mediated repression of Dachshund transforms layer 1/2- into layer 3/4-specific neurons. Hence, spatio-temporal relay mechanisms, bridging the distances between neuroepithelial domains and their postmitotic progeny, implement T4/T5 neuron-subtype identity.