FIGURE 6.

JNK1 is required for Netrin-1-mediated commissural axon attraction. A, schematic diagram of the commissural axon turning assay (20, 43, 44, 46). Venus YFP was electroporated into the neural tube of chick embryos for visualizing commissural axon projection. B–D, Netrin-1-induced axon turning was inhibited by SP600125. The neural tube was electroporated with Venus YFP alone and co-cultured with a cell aggregate secreting Netrin-1 in the absence (B) or presence of 1 μm (C) and 5 μm (D) SP600125. E and F, neural tube explants expressing the control JNK1 shRNA were co-cultured either with control HEK293 cells (E) or HEK293 cells secreting Netrin-1 (F). G and H, Venus YFP together with JNK1 shRNA or with JNK1 shRNA plus wild-type JNK1 were electroporated into chick neural tubes and explants cultured with Netrin-1 cells. Scale bar, 100 μm. I, quantification of axon turning. Data are mean ± S.E. *** indicates p < 0.001 (one-way ANOVA and Fisher LSD post hoc comparisons). Inh, inhibitor.