FIGURE 1.

PPARγ signaling pathway is severely compromised in mutant huntingtin-expressing cells. A, untreated striatal cells were double-labeled with an anti-actin antibody (green), and an anti-PPARγ antibody (red), and fluorescence images were captured. Representative images indicate that PPARγ expression is significantly decreased in mutant huntingtin-expressing cells in comparison with wild-type cells. B, top panel, representation Western blots for PPARγ and β-actin as a loading control; bottom panel, quantified data showing that the protein expression of PPARγ is significantly decreased in mutant huntingtin-expressing cells (45.1 ± 14.1, n = 9) compared with wild-type cells. C, PPARγ mRNA levels in mutant cells are significantly decreased compared with wild-type cells (0.367 ± 0.058, n = 6). D, mutant cells show significantly reduced PPARγ transcriptional activity in response to the PPARγ agonists rosiglitazone, 15-d-PGJ2, and LNO2. PPARγ activity was measured using a luciferase assay with a PPRE-Luc reporter (n = 6-8). All three agonists induced greater activation of PPARγ in wild-type cells (RSG, 2.04 ± 0.25; 15-d-PGJ2, 2.162 ± 0.13; LNO2, 2.46 ± 0.34) than mutant cells (RSG, 1.412 ± 0.10; 15-d-PGJ2, 1.70 ± 0.16; LNO2, 1.56 ± 0.11). Data are given as means ± S.E. ^*, #p < 0.05; ^**, p < 0.01; ^***, p < 0.001; p values with asterisk versus control condition in each cell type. #p is comparison between wild-type and mutant cells treated with the same agonist. Statistical significance was determined by Student's t test (A and B) and one-way ANOVA followed by Student-Newman-Keuls multiple comparisons test (C).