Figure 7

The length and branches of nerve tracts are reduced after Trappc9 deficiency in vivo. (A-C), Lentivirus-EGFP labeled neurons in olfactory bulb of adult mTrappc9^+/+ and mTrappc9 ^m/m mice. Lower panel shows the amplification result with arrowheads indicating relatively complete neurons. Lentivirus-EGFP was injected into the SVZ of adult mouse brain (2-3 months old), and one month later the EGFP-positive cells were examined. Branch points (B) and total lengths (C) of dendrites per neuron in the external plexiform layer were quantified. Neurons had smaller branches and shorter lengths in mTrappc9^m/m mice compared to mTrappc9^+/+mice. Representative images from n=4 mice/group (A); n=10 neurons (B, C). (D-F), Lentivirus-mediated siRNA knock-down in olfactory neurons in neonatal WT mice. The lentivirus carrying scrambled or mTrappc9-targeting siRNA expression cassette was injected intracerebroventricularly in P1 WT mice, and one month later the EGFP-positive cells were examined. The branch points (E) and total lengths (F) of dendrites in external plexiform layer were reduced in mTrappc9 knock-down mice. Representative images from n=3 mice/group (D); n=8 neurons (E, F). (G-I), Retrovirus-EGFP labeled dendrites in hippocampal dentate gyrus of adult mTrappc9^m/m and mTrappc9^+/+ mice. (H) Mushroom spine numbers of 50 μm terminal ends in labeled neurons; (I) the spine density. Dendritic spines were reduced in mTrappc9^m/m mice. Representative images from n=3 mice/group (G); n=10 neurons (H, I). (J) Graphical illustration depicting the effect of TRAPPII complex on neuronal development. Data are means ± SEM; t-test (B, C, E, F, H, I); ****P≤0.0001; ***P≤0.001; **P≤0.01; Scale bars: 150 μm (A); 50 μm (D); 0.5 μm (G).