Figure 4.

Immunoblot analysis and mitochondrial-dependent Ca²⁺ handling in STHdh cells treated with HDAC inhibitors. Shown are Q7 (left) and Q111 cells (right) under control conditions (no HDAC inhibitors added) and after treatment with either TSA (10 nm) or SB (1 mm) for 24 h. A, Immunoblot analysis. The anti-Htt antibody mAB2166 (1:250) recognized wild-type Htt (Htt-7Q) in Q7 cells and mutant Htt (Htt-111Q) in Q111 cells. As originally reported for these cells using the same antibody (Trettel et al., 2000), the mutant Htt band was less intense. This is not attributable to differences in protein loading as confirmed by tubulin labeling (anti-α-tubulin, 1:10,000). Acetyl-H3 labeling (anti-acetylated-histone-H3 antibody, 1:10,000) confirms effective HDAC inhibition. B, Densitometry analysis of immunoblots. Data are mean ± SEM of acetyl-H3/tubulin ratios in percentage of control Q7 cells. Significant differences: ***p < 0.001 versus control, ^###p < 0.001 versus TSA; n = 5 for control Q7 and Q111 cells, n = 2 for cells treated with HDAC inhibitors in both genotypes. C, Percentage of cells exhibiting “deregulation” [irreversible [Ca²⁺]_i elevation and mitochondrial depolarization (i.e., Rh123 dequenching)] in the 20 min between 4Br-A23187 challenging and oligomycin addition, in experiments performed exactly as those in Figure 2, A and D. Data are mean and SEM of n = 4–5 independent experiments, comprising a total of 312–401 Q7 and 289–400 Q111 cells per experimental group. Significant differences: ***p < 0.001 versus control. See Results for statistical details.