Fig. 5.

Cholesterol synthesis intermediates regulate NgBR expression

HepG2 cells in serum-free medium received the following treatment. A: atorvastatin at the indicated concentrations for 8 h; B: transfection with mature SREBP2 expression vector (pSREBP2-C2) for 16 h; C: HEK-293 T cells in 24-well plates were transfected with DNA for pNgBR promoter and pSREBP2 expression vector or empty vector, plus the DNA for Renilla luciferase (for internal control). After 4 h of transfection, cells were treated with 10 μM atorvastatin for 16 h followed by determination of activities of firefly and Renilla luciferases. *: P < 0.05; ns: not significantly different vs. pNgBR alone; D, E: mevalonate alone for 16 h (D) or mevalonate for 16 h and then plus atorvastatin for 5 h (E); F: FPP or GGPP at the indicated concentrations for 16 h and then FPP or GGPP plus atorvastatin for 5 h; G: manumycin A or GGTI-286 at the indicated concentrations for 5 h; H, I: GGOH or FOH (10 μM) for 16 h and then GGOH or FOH plus atorvastatin (10 μM) for 5 h. Expression of NgBR protein (A, B, D–I), endogenous SREBP2 precursor (P), mature SREBP2 (M), exogenous SREPB2 protein was determined by Western blot. All the experiments were repeated 3 times.