Expression of IGF-1R regulates neuronal migration. (a) Brains were electroporated with shRNA-IGF-1R (shIGF-1R/CAG-GFP) (right) or control shRNA/CAG-GFP (control-left), at E15 and analyzed at E19. Few GFP positive cells were located in the cortical plate (CP) and the marginal zone (MZ) when IGF-1R expression was knocked down compared to control. Calibration bar = 50 μm. (b) Quantification of the distribution of GFP-positive cells in CP, intermedial zone (IZ) and ventricular/subventricular zones (VZ/SVZ)as indicated in A. Student’s t test *p ≤ 0.05; **p ≤ 0.01; ns = not significant. (c) Brains were electroporated at E15 with shIGF-1R/CAG-GFP (middle), control shRNA/CAG-GFP (left) or co-electroporated with shIGF-1R/CAG-GFP plus cDNA coding for IGF-1R OPT and analyzed at P4. A few GFP positive cells are located in layers V-VI and noticeably fewer GFP positive cells are found in layers II-IV in the IGF-1R suppressed brain compared to the control. In contrast, an important accumulation of GFP positive cells was observed at the (VZ/SVZ/IZ) zones in the shRNA-IGF-1R brain. Note that co-transfection with cDNA coding for IGF-1R OPT (shRNA-refractive cDNA that will express the IGF-1R even in the presence of shRNA-IGF-1R) rescued the morphology. Calibration bar = 100 μm. (d) Quantification of the distribution of GFP positive neurons in VZ/SVZ/IZ, layers II-IV, V and VI as in c. Post hoc Turkey’s ANOVA **p ≤ 0.01 ***p ≤ 0.0001. n = 3 independent experiments. An average of 300 cells (a,b) or 500 cells (c,d) were scored for each condition.