Developmental changes in interkinetic nuclear migration dynamics with respect to cell-cycle progression in the mouse cerebral cortex ventricular zone.

We have examined the relationship between interkinetic nuclear migration (INM) and cell-cycle progression of apical progenitors in the ventricular zone (VZ) at different stages of mouse cerebral corticogenesis. We report stage-specific changes in INM due to a significant alteration of the nuclear apical movement dynamics with respect to cell-cycle phases. While at early stages, the apical nuclear movement corresponds to the G2 phase, cell-cycle phase specific immunostaining and real-time imaging of PCNA expressing apical progenitors revealed that at midcorticogenesis, the nuclear apical movement is initiated well before the entry into G2, during S phase. We observed that the S phase and G2 phase segments of the nuclear apical movement exhibit different velocities. Experimental shortening of cell-cycle duration via cyclin E overexpression in APs at midcorticogenesis leads to congruent INM behavior changes. This suggests that INM dynamics are under cell-cycle related constraints.