Figure 9.

Contactin2 is required for laminar targeting of neurites. GFP was introduced to large patches of retinal neurons, along with either a control miRNA (a–d) or miRNA Cntn2C (e–h). Sections were stained with antibodies to GFP to identify transduced regions (a, e); Cntn2 to assess the efficacy of the miRNA (b, f), Sdk1 to monitor processes of Cntn2-expressing neurons (c, g), and Sdk2 to assess the specificity of the effect (d, h). This strategy is based on the observation that ∼50% of Cntn2-positive neurons are Sdk1 positive but none is Sdk2 positive (see Fig. 7). Depletion of Cntn2 decreases the concentration of Sdk1-bearing processes in S4 (asterisk) and leads to their dispersion into neighboring zones. To quantify the dispersal, we measured the density of Sdk2 immunoreactivity as a function of laminar depth (i), then calculated the width of the curve at half-maximal intensity (j). The difference between control (n = 10) and Cntn2-depleted samples (n = 21) was significant (**p < 0.01). Scale bar, 10 μm.