We also found that the PCDH10 expression pattern and PCDH17 promoter-driven β-gal pattern were unaffected in basal ganglia ( Figures S4E and S4F). These findings strongly suggested that PCDH17 is not involved in topographic map formation along corticobasal ganglia circuits. We then performed electron microscopic analysis of synaptic morphology in 3-week-old wild-type and PCDH17−/− mice. In excitatory asymmetric synapses of the anterior striatum, where PCDH17 Gefitinib solubility dmso expression was evident, PCDH17 deficiency caused significant increases in the number of docked SVs and the total number of SVs per presynaptic terminal, whereas in the posterior

striatum where PCDH17 expression was weak, these parameters did not exhibit significant changes ( Figures

5A and 5B). Other parameters, Saracatinib manufacturer such as average postsynaptic spine area, PSD length, synaptic cleft width, and the density of asymmetric synapses, were similar in wild-type and PCDH17−/− sections ( Figures 5B and 5C). We also investigated inhibitory symmetric synapses of the LGP as output nuclei from the striatum. Increased numbers of docked SVs and total SVs per presynaptic terminal were observed in the inner LGP, but not in the outer LGP after PCDH17 ablation ( Figures 5D and 5E). Synaptic cleft width and density of symmetric synapses were similar in both zones ( Figures 5E and 5F). There were no changes in synapse densities ( Figures 5C and 5F) or the expression of presynaptic proteins in PCDH17−/− mice ( Figure S3E). Only an increased number of docked SVs and total SVs per presynaptic terminal were observed in PCDH17−/− neurons. Taken together, PCDH17 appears to regulate presynaptic SV assembly at both excitatory synapses on MSNs and inhibitory synapses on LGP neurons in each zone-specific region. To evaluate the role of PCDH17 in SV assembly in vitro, we overexpressed PCDH17

in cultured cortical neurons in concert with synaptophysin-EGFP (Syn-EGFP), which is an SV marker used to monitor SV assembly (Bamji et al., 2003). In the axons of control cells, Syn-EGFP exhibited rounded, Rebamipide punctate clusters. In contrast, Syn-EGFP puncta that were originally associated with PCDH17 puncta became more diffuse in PCDH17-overexpressing neurons (Figures S5A and S5B), suggesting that expression of PCDH17 inhibits the accumulation of SVs. Because inhibition of SV assembly to the presynaptic terminal promotes SV cluster movements (Bamji et al., 2003), we examined whether overexpression of PCDH17 affected the mobility of SV clusters. While Syn-EGFP large puncta were stable or slow-moving in control axons, Syn-EGFP large puncta were relatively mobile and exhibited coordinated movement with PCDH17-mCherry puncta in PCDH17-overexpressing axons (Figures S5C–S5E; Movies S1 and S2). These findings demonstrate that PCDH17 clusters are mobile elements and that PCDH17 overexpression promotes the mobility of SV clusters along axons.