RT Journal Article SR Electronic T1 Drosophila Fezf coordinates laminar-specific connectivity through cell-intrinsic and cell-extrinsic mechanisms JF bioRxiv FD Cold Spring Harbor Laboratory SP 231399 DO 10.1101/231399 A1 Ivan J. Santiago A1 Jing Peng A1 Curie Ahn A1 Burak Gür A1 Katja Sporar A1 Chundi Xu A1 Aziz Karakhanyan A1 Marion Silies A1 Matthew Y. Pecot YR 2017 UL http://biorxiv.org/content/early/2017/12/08/231399.abstract AB Laminar arrangement of neural connections is a fundamental feature of neural circuit organization. Identifying mechanisms that coordinate neural connections within correct layers is thus vital for understanding how neural circuits are assembled. In the medulla of the Drosophila visual system neurons form connections within ten parallel layers. The M3 layer receives input from two neuron types that sequentially innervate M3 during development. Here we show that M3-specific innervation by both neurons is coordinated by Drosophila Fezf (dFezf), a conserved transcription factor that is selectively expressed by the earlier targeting input neuron. In this cell, dFezf instructs layer specificity and activates the expression of a secreted molecule (Netrin) that regulates the layer specificity of the other input neuron. We propose that employment of transcriptional modules that cell-intrinsically target neurons to specific layers, and cell-extrinsically recruit other neurons is a general mechanism for building layered networks of neural connections.