Medicine and Health Sciences Commons^™

Ephrin-B3 Controls Excitatory Synapse Density Through Cell-Cell Competition For Ephbs., Nathan T. Henderson, Sylvain J. Le Marchand, Martin Hruska, Simon Hippenmeyer, Liqun Luo, Matthew B. Dalva

Department of Neuroscience Faculty Papers

Cortical networks are characterized by sparse connectivity, with synapses found at only a subset of axo-dendritic contacts. Yet within these networks, neurons can exhibit high connection probabilities, suggesting that cell-intrinsic factors, not proximity, determine connectivity. Here, we identify ephrin-B3 (eB3) as a factor that determines synapse density by mediating a cell-cell competition that requires ephrin-B-EphB signaling. In a microisland culture system designed to isolate cell-cell competition, we find that eB3 determines winning and losing neurons in a contest for synapses. In a Mosaic Analysis with Double Markers (MADM) genetic mouse model system in vivo the relative levels of eB3 control …