Figure 3. ER–mitochondrial apposition is regulated by C99.

1. Localization of ER (green) and mitochondria (red) in the indicated MEFs without and with BACE1 inhibitor (inhibiting C99 formation; see Western in panel B). Large boxes in the Merge are enlargements of the small boxes. Scale bars = 20 μm.
2. Quantitation by ImageJ analysis of the colocalization of ER and mitochondrial signals from experiments like the one shown in (A) (average of n = 4 independent experiments ± SD). *P < 0.05. Analysis by unpaired t‐test. The Western blot indicates the APP‐CTF levels in the indicated cells (30 μg of protein per lane).
3. ACAT1 activity in WT and PS‐DKO MEFs in the presence and absence of α‐, β‐, and/or γ‐secretase inhibitors (average of n = 4 independent experiments ± SD). *P < 0.05. Analysis by unpaired t‐test. ACAT activity was normalized by controls (WT incubated with vehicle [DMSO]).
4. Staining of the indicated cells with LipidTox Green to detect lipid droplets. Scale bars = 20 μm.