Figure 7. Gpsm2 mutation leads to hypoplasia of the corpus callosum and affects growth cone outgrowth.
(a) Hematoxylin staining of coronal sections from P6 Gpsm2Emx1 control (upper panel) and cKO brains (lower panel) at a caudal levels. Note the abscence of corpus callossum (CC) in the cKO mouse (inset). Scale bar, 1 mm, n=4 independent experiments. (b,c) In cultured hippocampal neurons at DIV2, N-cadherin-dependent outgrowth was reduced in Gpsm2 cKOs, but not in Gnai3 cKOs (b). The reduction in outgrowth was maintained on a laminin substrate in Gpsm2 cKOs (c). Data from three to six independent experiments are presented as whisker box plots (min/max) (n=number of growth cones). ***P<0.001 with unpaired Student’s t-test. (d) Images from three time points (0, 15 and 30 min) of a time-lapse movie from 2 DIV control and Gpsm2 cKO hippocampal neurons plated on N-cadherin-coated glass and showing the difference in distance covered (dotted lines and double-headed arrows). Scale bar=10 μm. (e) Quantification of the average number of pauses (±s.e.m.) during a 30 min period of growth cones from control (n=31 neurons) compared with Gpsm2 cKO (n=51 neurons), from four independent experiments. The Gpsm2 cKO growth cones pause more than controls. ***P<0.001, *P<0.05 with unpaired Student’s t-test. (f) Cumulated distance covered by control and Gpsm2 cKO growth cones over a 30 min period. Some pauses are indicated with blue arrows.