Fig 3.

Radial neuronal migration requires downregulation of KLF4. (A and B) Constitutive KLF4 expression inhibits proliferation of neural progenitors in vivo. Brains were electroporated at E14.5 and examined at E17.5. Proliferating cells were labeled by PCNA staining (red signal in panel A) and quantified by counting PCNA⁺ GFP⁺ cells in ventricular zone/subventricular zone. n = 5; **, P < 0.01. Scale bar, 50 μm. (C and D) Radial neuronal migration is impaired by constitutive KLF4 expression. E14.5 mouse embryos were electroporated in utero with GFP or KLF4-GFP plasmids and examined at E17.5. Coronal sections were counterstained with Hoechst (blue signal). Very few KLF4-expressing cells migrated to the cortical plate (CP). n = 5; **, P < 0.01; ***, P < 0.001. Scale bar, 100 μm. (E and F) Multipolar-to-bipolar transition of migrating neurons is compromised by KLF4. Images were taken from the intermediate zone. Brains were electroporated at E14.5 and examined at E17.5. Arrows and arrowheads show cells with uni- or bipolar and multipolar morphologies, respectively. n = 5; *, P < 0.05; **, P < 0.01. Scale bar, 20 μm. IZ, intermediate zone; VZ, ventricular zone; SVZ, subventricular zone.