Figure 4

Inhibition of miR-29b induces a profound defect in corticogenesis during brain development. (a) Experimental scheme for in utero electroporation. RNA duplexes were electroporated at E13.5, and mouse cerebral cortices were harvested at E16.5 and E18.5. (b–e) The cortical plate at E16.5 shows TBR1-positive early pyramidal neuronal cells (red) and reelin (RELN)-expressing cells in the marginal zone (yellow). Anti-miR-29b oligonucleotides were microinjected into the left ventricle of mouse embryos at E13.5. Inhibition of miR-29b by in utero electroporation of anti-miR-29b into embryonic mouse brains led to premature outward cortical migration. Cells transfected with control siRNA radially migrated at the cortical marginal zone and showed a normal distribution of reelin expression. In contrast, reelin-positive Cajal–Retzius neurons in the marginal zone were decreased in brains microinjected with anti-miR-29b. MZ, marginal zone; CP, cortical plate; SC, subplate cells; IZ, intermediate zone, SVZ, subventricular zone; VZ, ventricular zone. Data are expressed as mean±S.E.M. values (error bars) or assays performed in triplicate