Figure 5.

Src-type tyrosine kinase inhibitors block Sema3A-induced PSD-95 clustering. PP2 but not PP3 suppressed the effect of Sema3A (3 nm) on PSD-95 clusters, and Sema3A fails to induce PSD-95 cluster formation in fyn^−/− neurons. A, PSD-95 clusters in cultured cortical neurons treated with (b, d) and without (a, c) Sema3A. PP2 (a, b) or PP3 (c, d) (0.4 μm) was applied 30 min before Sema3A. Scale bar, 10 μm. B, Quantitative analysis of the effects of PP2 and PP3 on the density of PSD-95 clusters. Images of 10 typical neurons from two independent culture preparations were recorded, and the density of PSD-95-clusters was measured. C, Quantitative analysis of the effects of PP2 and PP3 on the area of PSD-95 clusters. Images of 10 typical neurons from two independent culture preparations were recorded, and the area of PSD-95 clusters was measured. D, Quantitative analysis of the effect of lavendustin A on the density of PSD-95 clusters. E, The cultured cortical neurons from fyn^−/− mice were applied with (b) or without (a) Sema3A (3 nm) and were double stained with anti-PSD-95 (green) and rhodamine–phalloidin (purple). Scale bar, 10 μm. F, There were few dendritic spine-like protrusions in fyn^−/− neurons, and Sema3A induced neither PSD-95 clustering nor spine-like protrusion on dendrites. *p < 0.001 compared with Sema3A at 0 nm; ^†p < 0.001 compared with corresponding value in wild type (wt).