Figure 4
From: Control of cortex development by ULK4, a rare risk gene for mental disorders including schizophrenia
Silencing Ulk4 massively perturbs radial migration and neurite arborization.
(A) In the control cortex, almost all the neurons traced with GFP at E15.5 have migrated successfully into layers II–III at P7; (B) Instead of being present in superficial layers, large amounts of GFP-traced cells are “trapped” in cortical layers IV–VI in shRNA268 knockdown groups. (C,D,F) Ulk4 knockdown with shRNA268 dramatically reshapes neurite branching. Most of the mislocated GFP neurons bear a stalled apical dendrite (white arrows) with some having an ectopic apical dendrite (C, asterisks and yellow arrow; F, asterisks) or long secondary dendritic branching (F, white arrowheads). (E) In the control brains, GFP-positive pyramidal neurons develop a predominant apical dendrite (white arrows) which ends and elaborates in layer I. White broken line shows the pial surface and the yellow broken line delineates the boundary between lamina I and II. (G) Compared with control brains (black columns), there are significantly more cells in deeper cortical lamina and subtantially less cells in layers II–III in the shRNA268 knockdown cortex (gray columns). *p < 0.05. **p < 0.01. (H,I) Compared with control brains (H), shRNA269 leads to dispersed layers II–III which contain loosely-packed GFP cells (I). White arrow in I shows a neuron with two apical dendrites which is also enlarged in inset i. (J–N) Confocal images of abnormal cell morphology in shRNA269 knockdown brains. Some cells develop multiple dendrites directly from the soma with (N, white arrow and inset n) or without the predominent apical dendrite (J, white arrow). Inset n is the enlarged view of the white arrowed neuron in N. In addition, many GFP-positive cells have stalled (K,L, white arrows) or aborted (K,L, slim white arrows) apical dendrites which are frequently replaced by ectopic apical dendrites (K,L, white arrowheads) or long secondary dendritic branching (K, asterisks). (M) Clusters of GFP-postive cells are disoriented and do not present typical polarity of pyramidal neurons (aligned perpendicularly to brain surface). Broken white lines in (J,N) indicate the brain surface and the boundary between layers I and II in (M). Bars = 100 μm in (A,B), 20 μm in (C–N) and associated insets.
