MH002: FoxO6 is required for Plxna4-mediated neuronal migration during cortical development. Mus musculus

The forkhead transcription factor FoxO6 is prominently expressed during development of the murine neocortex. However, its function in cortical development is as yet unknown. We now demonstrate that cortical development is altered in FoxO6+/- and FoxO6-/- mice, showing migrating neurons halted in the intermediate zone. Using a FoxO6-directed siRNA approach, we substantiate the requirement of FoxO6 for a correct radial migration in the developing neocortex. Subsequent genome-wide transcriptome analysis reveals altered expression of genes involved in cell adhesion, axon guidance, and gliogenesis upon silencing of FoxO6 We then show that FoxO6 binds to DAF-16-binding elements in the Plexin A4 (Plxna4) promoter region and affects Plxna4 expression. Finally, ectopic Plxna4 expression restores radial migration in FoxO6+/- and siRNA-mediated knockdown models. In conclusion, the presented data provide insights into the molecular mechanisms whereby transcriptional programs drive cortical development. Overall design: In utero knockdown of FoxO6 was done on C57/BL6 mice embryos at E14.5 with either siFoxO6-2 or siFoxO6-3 both targeting FoxO6 specifically or the control siRNA Scrambled. All cortices were co-transfected with GFP. At E16.5, embryos were harvested, cortex was isolated and dissociated followed by FAC sorting. Sorted cells were subjected to RNA isolation, cortices were pooled into 4 independent pools per FoxO6 si-RNA, and 1 reference pool for the non-targeting control siRNA to minimize effects due to electroporation differences. Per si-RNA, 2 samples were labeled normal and 2 in dye swap against the common reference, and hybridized on a mouse expression microarray.