Neurexin Clusters Neuroligins but Not Dystroglycan
(A) Coculture of fibroblasts expressing neurexin-1β-CFP with neurons resulted in only endogenous synaptic clusters (arrows) but no induced clusters of β-dystroglycan at contacts with dendrites.
(B and C) Fibroblasts expressing neurexin-1β-CFP cocultured with hippocampal neurons expressing YFP-neuroligin-1 (B) or YFP-neuroligin-2 (C) induced clusters of YFP-neuroligin lacking immunoreactivity for synapsin in contacting dendrites. The transfected neuron is indicated by *.
(D) Fibroblasts expressing neurexin-1β-CFP cocultured with hippocampal neurons expressing YFP-neuroligin-1 induced overlapping clusters of recombinant YFP-neuroligin-1 and endogenous neuroligin-2 in contacting dendrites. Smaller clusters of gephyrin and PSD-95 were apparent within the neuroligin-positive dendrite regions.
(E) Fibroblasts expressing neurexin-1β-CFP cocultured with hippocampal neurons induced clusters of neuroligin-2, gephyrin, and PSD-95 in contacting dendrites. Within the neurexin contact region as assayed by confocal microscopy, gephyrin clusters were nearly all associated with high concentrations of neuroligin-2, whereas the association of PSD-95 clusters with neuroligin-2-immunopositive regions was more variable.
Scale bars (A)-(C) 10 μm, (D) and (E) 5 μm.