Figure 6. Synaptic vesicle component SV2 is reduced in GA aggregate containing neurons.

eGFP‐GA_n dipeptides were expressed in primary cortical or motor neurons for 48 h, and then immunostained for neurofilament (gray) and SV2 (red).

• A, B
  Representative z‐stack confocal images of neurites from eGFP, eGFP‐GA₅₀, and eGFP‐GA100 expressing cortical (A) or motor (B) neurons. 60× magnification, scale bar indicates 5 μm.
• C, D
  Quantification of SV2 puncta along neurites in cortical neurons (C) or motor neurons (D) by ImageJ manual counting, normalized to eGFP‐only expressing cells. (C) Cortical neurons demonstrated a significant GA length‐dependent reduction, as well as a reduction in all cells containing GA repeats greater than 50 (left panel). (D) Motor neurons demonstrated a significant GA length‐dependent reduction, as well as a reduction in all cells containing GA repeats greater than 100 (left panel). Evaluation of neurite length by NeuronJ software revealed no differences in total neurite length per cell in cortical neurons (C) or motor neurons (D) expressing any GA repeat length compared with eGFP alone (right panels).

Data information: Data presented as mean ± SEM. One‐way ANOVA, post hoc Dunnett's multiple comparison test, ****P < 0.0001, n = 3 independent biological replicates, m = 5–7 cells per replicate. Exact P‐values can be found in Appendix Table S1.