Figure 4. Promethazine reduces DPR protein accumulation and toxicity.

1. Left panel, immunoblotting against the HA‐tag or the GAPDH of proteins extracted from Neuro2A cells transfected for 24 h with a construct expressing 80 G4C2 repeats embedded in the human sense C9ORF72 sequence fused to a HA in the GA frame and treated with 10 μM of the indicated compound for 15 h. Right panel, quantification of polyGA expression relative to the GAPDH.
2. Left panel, immunoblotting against the HA‐tag or the GAPDH of proteins extracted from Neuro2A cells transfected for 24 h with a construct expressing 100 C4G2 repeats embedded in the human antisense C9ORF72 sequence fused to a HA‐tag in the PG frame and treated with 10 μM of the indicated compound for 15 h. Right panel, quantification of polyPG expression relative to the GAPDH.
3. Cell viability (TO‐PRO‐3 FACS staining) of GT1‐7 neuronal cells treated with 1, 3, or 10 μM of promethazine and co‐transfected for 24 h with either a control siRNA or a siRNA targeting C9orf72 mRNA and a construct expressing either 80 G4C2 repeats or 100 C4G2 repeats embedded in sense or antisense C9ORF72 fused to the GFP in the GA or PG frame.

Data information: Error bars indicate s.e.m. Student's t‐test, **P < 0.01, and ***P < 0.001. n = 5 independent transfection.