PI3K and AKT inhibition, but not mTORC1, affects neuronal
differentiation in NPCs. (A) Western blot analysis of AKT (Thr308) and S6
phosphorylation in control and TSC NPCs treated with 5 μM RAD001 or DMSO
for 48 hours. (B, C) Quantification of Western blot data for the RAD001
treatment. Phospho-S6 (pS6) levels were significantly higher in TSC-DMSO
compared to CTR-DMSO samples, but were strongly reduced by RAD001 treatment (B),
whereas significantly lower levels of phospho-AKT (pAKT) were unaffected (C)
(*p<0.05, ***p<0.001,
****p<0.0001, n=6 DMSO-treated
cultures, n=3 RAD001-treated cultures). Significance was
determined via one-way ANOVA with Tukey’s post-hoc analysis. (D, E)
Western blot analysis of AKT (Thr308) and S6 phosphorylation in control NPCs
treated with 1 μM MK2206, 10μM LY294002 or DMSO for 24 hours. (F)
Quantification of the pAKT data. Both subject groups show significantly
attenuated pAKT levels in MK2206-treated as well as LY294002-treated cultures
compared to DMSO controls (*p<0.05,
**p<0.01, ***p<0.001,
n=3 cultures of 3 independent cell lines per subject).
Significance was determined via one-way ANOVA with Dunnett’s multiple
comparisons tests. (G) Representative confocal images of CTR #8 and TSC #6
cultures treated with DMSO, 5μM RAD001, 1μM MK2206 or 10μM
LY294002, and differentiated for 7 DIV. Cultures were immunostained for the
pan-neuronal marker HuC/D and counterstained with Hoechst. Scale bar =
50μm. (H, I) Automated high content analysis of treated culture images
from both subject sets. The fraction of HuC/D+ cells was calculated from
3–6 experiments using 3 independent lines per subject, normalized to the
internal control in each set (CTR+DMSO), and expressed as fold change.
Significance was determined via one-way ANOVA with Dunnett’s multiple
comparisons tests. (H) The fraction of HuC/D+ cells was significantly reduced in
TSC #6+DMSO compared to CTR #8+DMSO cultures, and treatment with RAD001 did not
rescue the defect. The fraction of HuC/D+ cells was similarly reduced in CTR
#8+MK2206 and CTR #8+LY294002 cultures, but was not altered in CTR #8+RAD001
cultures. **p<0.01, ***p<0.001,
n=4 independent cultures (RAD001 treatment),
n=3 (MK2206 and LY294002 treatments), n=6
(DMSO). (I) The fraction of HuC/D+ cells was significantly reduced in MK2206-
and LY294002-treated cultures compared to DMSO-treated CTR #5 cultures.
*p<0.05, **p<0.01,
n=3 independent experiment per treatment. Plots represent
mean values ± SEM.