Deletion of the Cupidin Cdc42-binding domain influences synapse formation and function in hippocampal neurons. (A) The left panel shows secondary dendrites of hippocampal neurons expressing GFP, GFP-CPD and GFP-CPDΔ191–230 fluorescence (green) following recombinant adenovirus infection were immunostained for synaptophysin (red). The middle graph indicates the relative numbers of synaptophysin-positive puncta along the dendrites overexpressing either GFP-CPD or GFP-CPDΔ191–230 (= GFP-Δ191–230) were quantified and normalized to those of dendrites overexpressing GFP alone, which was set to 1.0 The right graph shows the proportions of GFP-CPD- and GFP-CPDΔ191–230-positive puncta that were co-localized with synaptophysin puncta. *, p < 0.001. Bar: 5 μm. (B) Neurons were infected with the adenovirus vectors containing GFP-CPD, GFP-CPDΔ191–230 (= GFP-Δ191–230) or GFP alone (see Methods) and their ionotropic receptor-mediated mEPSCs were recorded at DIV21. Example recordings of mEPSCs obtained from neurons expressing GFP only (upper trace), GFP-CPD (middle trace), and GFP-CPDΔ191–230 (lower trace). (C) Cumulative frequency plots of mEPSC peak amplitude and interval in neurons expressing GFP only (black line), GFP-CPD (blue line) or GFP-CPDΔ191–230 (red line). Insert: overlapped average of 100 mEPSCs for each construct.