Figure 4. Cilia-Localization-Deficient Arl13b Is Sufficient for Shh-Mediated Growth Cone Turning In Vitro and Commissural Axon Guidance In Vivo.
(A) Arl13b-GFP or Arl13bV358A-GFP localization in commissural neurons. Arrows: primary cilia. Arrowheads: growth cones.
(B) Commissural neurons expressing scrambled shRNA, shArl13b, or shArl13b + cilia-localization-deficient Arl13b (V358A) exposed to a gradient of Shh (0.1 μg/ml) or BSA.
(C and D) Rose histograms (C) or standard histogram (D) of the angle turned (mean ± SEM) (one-way ANOVA, Tukey’s multiple comparison post-test, **p < 0.01, n > 30 neurons per condition).
(E) IFT88 and Arl13b co-immunostaining of E11.5 spinal cord cross-sections of Arl13bV358A/V358A mice compared to control mice.
(F) Robo3 immunostaining of E11.5 spinal cord cross-sections of Arl13bV358A/V358A mice compared to control mice.
(G) Quantification of the area occupied by Robo3+ axons relative to the total area of the ventral neural tube (mean ± SEM) (t test). Number of embryos: 4 Arl13bV358A/V358A; 4 control; and 2 sections per embryo.
Scale bars: 20 μm (A), 10 μm (B and E), and 200 μm (F).
See also Figures S2 and S3.