Figure 4.

Aβ facilitates HIF1α synthesis and autophagy inhibition via mTOR activation. (A) SK-N-MC cells were exposed to Aβ (5 μM) for 0–48 h. HIF1α and β-actin expression was analyzed by western blot. n = 3. (B) Cells were pretreated with NAC (1 mM) for 30 min prior to Aβ treatment for 24 h. HIF1α and β-actin expression were analyzed by western blot. n = 3. (C,E) Cells were incubated with rapamycin (10 nM) for 30 min prior to Aβ treatment for 24 h. Phosphorylation of 4EBP1 (Thr 37/46) and 4EBP1, phosphorylation of p70S6K1 (Thr 389), HIF1α and β-actin were analyzed by western blot. n = 6. (D) Protein samples were immunoprecipitated by eukaryotic translation initiation factor 4E (eIF4E) antibody-conjugated protein A/G agarose beads. Samples were blotted with 4EBP1 and eIF4E-specific antibodies. n = 3. (F) Cells were exposed to PF4708671 (10 μM) for 30 min prior to Aβ treatment for 24 h. HIF1α and β-actin expression was detected by western blot. n = 6. (G) Cells were exposed to cycloheximide (4 μM) for 30 min prior to Aβ treatment for 24 h. HIF1α and β-actin expressions were detected by western blot. n = 6. (H) Cells were pretreated with rapamycin (10 nM) for 30 min, incubated with Aβ for 24 h and analyzed by western blotting with LC3, p62 and β-actin specific antibodies. n = 3–6. (I) LC3 puncta was visualized by confocal microscopy. Presented results are merged images. Green and red fluorescents indicate LC3 and PI respectively. Scale bars, 50 μm (magnification × 600). (J) Cells were pretreated with trehalose (10 μM) for 30 min prior to Aβ treatment for 24 h. Cytotoxicity was measured by MTT assay at an absorbance of 545 nm using a microplate reader. Data present the mean ± SE. n = 6. (K) Cell viability was measured by trypan blue exclusion assay. Data are presented as a mean ± SE. n = 6. Each blot image was presented as representative image. *p < 0.05 vs. control, ^#p < 0.05 vs. Aβ treatment.