Neuroligin-1 overexpression transiently increases dendritic process number.

<p>A. HA-neuroligin-1 expression pattern in 14-day-old adult-born granule cells, visualized with anti-HA staining. Exogenous neuroligin-1 is expressed throughout the dendritic tree (left; scale bar, 10 µm.) and is concentrated along filopodium-like protrusions from the dendritic shaft (right; scale bar: 5 µm). B, C. Dendritic tree morphology of representative 14-day-old neurons shows an increased number of processes along the dendritic tree of neuroligin-1 overexpressing cells. Scale bar: 25 µm. D, E, F. Summary data for 14 day old neurons shows no difference in cell soma size, but a neuroligin-1 mediated increase in total dendritic length and dendritic process number (shown ± SEM, control, n = 12 cells; NLG-1, n = 11 cells; *** p<0.005). G. Dendritic branch (Sholl) analysis demonstrates increased branching along more distal dendrites in neuroligin-1 overexpressing 14-day-old cells (* p<0. 01, two way repeated measures ANOVA). The shaded areas correspond to the average distance from each soma to the granule cell layer (GCL)-inner molecular layer (IML) border in the two groups (n.s.). H. Overlay of Sholl analyses from 14 and 21 day old neurons. Between 14 and 21 days, granule cell dendrites grow to span the full width of the dentate molecular layer and basal dendrites (10–20 µm from soma) retract.