FIG 8.
Reciprocal regulation of SREBP processing by 25-hydroxycholesterol or statins respectively inhibits or activates IDH1 expression in IDH1R132C mutant cells. (A and B) Cells were treated with 25-HC (1 μg/ml) for 48 h prior to RNA isolation for analysis by qRT-PCR (A) or 0, 1, 2, or 3 days prior to lysis for immunoblot analysis (B). (C to E) Cells were cultured in the presence of atorvastatin at 5 μM (C) or simvastatin at 5 μM (D) for 48 h prior to RNA extraction for qRT-PCR analysis or for 0, 1, or 2 days prior to lysis for immunoblot analysis (E). In panels A, C, and D, the transcript levels are shown as means ± the SEM relative to untreated cells (n = 3; *, P < 0.05). In panels B and E, the immunoblots shown are representative of at least two independent experiments. (P), precursor, full-length SREBP2; (M), mature, active SREBP2.