Data from: An extracellular biochemical screen reveals that FLRTs and Unc5s mediate neuronal subtype recognition in the retina

In the inner plexiform layer of the mouse retina, ~70 neuronal subtypes form a stereotyped circuit that underlies visual processing. During development, subtypes organize into an intricate laminar structure. This organization is choreographed by extracellular interactions that mediate cell recognition events. To identify recognition proteins involved in lamination, we utilized microarray data from 13 subtypes to identify differentially-expressed cell surface and secreted proteins. Using these candidates, we performed a biochemical screen and identified ~50 previously-unknown receptor-ligand pairs. We tested the response of retinal neurons to several candidates and found that both members of one interaction pair, FLRT2-Unc5C, induce repulsion; each in a different neuronal subtype(s). Consistent with a repulsive role in mediating lamination, we observed a complementary expression pattern of FLRT2 and Unc5C in vivo. We identified that Starburst amacrine cells express FLRT2 and are repelled by Unc5C. These data support a repulsive mechanism for laminar restriction of Starburst amacrines

Mouse retina extracellular receptor-ligand biochemical screen

Biochemical screen for extracellular receptor-ligand interactions in the developing mouse retina. The extracellular domain (ECD) region of 126 cell surface or secreted proteins were tested for pairwise binding in a matrix. ECDs along the x-axis were C-terminally fused to the Fc region of human IgG1. ECDs along the y-axis were C-terminally fused to alkaline phosphatase (AP). Proteins were tested for binding using a high-throughput, ELISA-based binding assay. In this assay, ECD-AP receptor protein is captured on an ELISA plate using an anti-AP antibody. Binding of ECD-Fc ligand protein to the ECD-AP receptor protein is detected by inclusion of an anti-Fc antibody conjugated to HRP. HRP activity is measured using O.D. 650 nm one hour following addition of substrate. Raw data values are reported