Cortical interneurons migrating on a pure substrate of N-cadherin exhibit fast synchronous centrosomal and nuclear movements and reduced ciliogenesis

The embryonic development of the cortex involves a phase of long distance migration of interneuronsborn in the basal telencephalon. Interneuronsfirst migrate tangentially and then reorient their trajectories radially to enter the developing cortex. We have shown that migrating interneuronscan assemble a primary cilium, which maintains the centrosometo the plasma membrane and processes signals to control interneurontrajectory (Baudoin et al., 2012). In the developing cortex, N- cadherinis expressed by migrating interneuronsand by cells in their migratory pathway. N- cadherinpromotes the motility and maintains the polarity of tangentially migrating interneurons(Luccardini et al., 2013). Because N- cadherinis an important factor that regulates the migration of medial ganglionic eminence(MGE) cells in vivo, we further characterized the motility and polarity of MGE cells on a substrate that only comprises this protein. MGE cells migratingon a N- cadherinsubstrate were seven times faster than on a lamininsubstrate and two times faster than on a substrate of cortical cells. A primary ciliumwas much less frequently observed on MGE cells migratingon N- cadherinthan on laminin. Nevertheless, the mature centriole(MC) frequently docked to the plasma membrane in MGE cells migratingon N- cadherin, suggesting that plasma membrane docking is a basic feature of the centrosomein migrating MGE cells. On the N- cadherinsubstrate, centrosomaland nuclear movements were remarkably synchronous and the centrosomeremained near the nucleus. Interestingly, MGE cells with cadherininvalidation presented centrosomalmovements no longer coordinated with nuclear movements. In summary, MGE cells migratingon a pure substrate of N- cadherinshow fast, coordinated nuclear and centrosomalmovements, and rarely present a primary cilium.