FIGURE 2.

SHP is down-regulated during pregnancy and represses HNF4α transactivation of CYP2D6. A, liver tissues were collected from Tg-CYP2D6 mice at pre-pregnancy (Virgin), 7/14/21 days of pregnancy (G7, G14, and G21, respectively), or 7 days postpartum (PP7), and total RNA and lysates were prepared from the tissues. mRNA levels of Hnf4α were determined by qRT-PCR (n = 4, mean ± S.D.; *, p < 0.05; **, p < 0.01, one-way ANOVA versus virgin). B, ChIP assays were performed using liver tissues of Tg-CYP2D6 mice collected at different gestational time points (n = 4, mean ± S.D.; *, p < 0.05; **, p < 0.01, one-way ANOVA versus virgin). C and D, mRNA and protein levels of SHP in liver tissues were determined by qRT-PCR and Western blot, respectively. A representative image of Western blot (D, right) and the quantified band intensities (D, left; n = 4, mean ± S.D.; **, p < 0.01, one-way ANOVA versus virgin) are shown. E, CYP2D6 promoter activity was examined by dual luciferase assay in HEK293T cells (n = 3, mean ± S.D.). F, Tg-CYP2D6 mice were injected with scrambled siRNA (siRNA-control) or siRNA targeting SHP (siRNA-SHP), and mRNA expression levels were determined by qRT-PCR (n = 3, mean ± S.D.; **, p < 0.01, Student's t test versus siRNA-control). G, ChIP assays were performed using liver tissues of Tg-CYP2D6 mice collected at different gestational time points (n = 4, mean ± S.D.; *, p < 0.05; **, p < 0.01, one-way ANOVA versus virgin).