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. Author manuscript; available in PMC: 2013 Nov 3.
Published in final edited form as: Mol Pharmacol. 2008 Jun 13;74(3):10.1124/mol.108.048983. doi: 10.1124/mol.108.048983

Fig. 4. Effects of coactivators on the synergistic activation of CYP2C9 promoter expression by HNF4α and CAR in HepG2 cells.

Fig. 4

(a) NCOA6 does not effect CAR mediated transactivation. HepG2 cells were transfected with CAR, NCOA6 and PGC-1α along with CYP2C9 reporter construct, in the presence (hatched bars) and absence (solid bars) of 100nM CITCO as the ligand with pRL as the internal control. All transfections were performed in triplicate. Values are means of triplicates + SE. CAR significantly upregulates the CYP2C9 promoter in the absence and presence of ligand at *, p<0.05, **,p<0.01, ***, p<0.001. Transfection with PGC-1α and CAR significantly transactivates the CYP2C9 promoter more than CAR alone at †††, p<0.001, while NCOA6 had no effect.

(b) Effect of NCOA6 and PGC-1α on HNF4α mediated transactivation. HNF4α and NCOA6 were expressed along with the CYP2C9 promoter in HepG2. *, p<0.05 **, p<0.01and ***, p<0.001.values are significantly greater than CYP2C9 promoter alone. NCOA6 alone does not transactivate CYP2C9 promoter. Cotransfection with PGC-1α and HNF4 α activates the CYP2C9 promoter significantly greater than HNF4α alone at ††† , p<0.001. (c) CAR and HNF4α synergistically activate CYP2C9 promoter expression in the presence of CITCO and the effect of coactivatosr NCOA6 and PGC-1α . HepG2 cells were transfected with CAR and HNF4α individually and in combination, coactivators NCOA6 and PGC-1α were added to CAR-HNF4 combination in the presence (hatched bars) and absence of 100 nM CITCO as the ligand with CYP2C9 reporter constructs. All transfections were performed in triplicate and values represent the means + SE. The values represent fold activation over CYP2C9 promoter alone. CAR, HNF4α or CAR+ HNF4α significantly upregulate CYP2C9 promoter activity compared to CYP2C9 promoter alone, at *, p<0.05, **, p<0.01, ***, p<0.001. †††, designates synergistic rather than additive response to cotransfection with HNF4α and CAR at p<0.001 (ANOVA with interaction). Transfection with NCOA6 significantly enhances the activation of CAR and HNF4α at p<0.01, ##, while transfection with PGC-1α had no significant effect.