Possible involvement of nuclear factor erythroid 2-related factor 2 in the gene expression of Cyp2b10 and Cyp2a5

Abstract

Cytochrome P450 gene expression is altered by various chemical compounds. In this study, we used nuclear factor erythroid 2-related factor 2 (Nrf2)-deficient (Nrf2(-⧸-)) mice to investigate the involvement of Nrf2 in Cyp2b10 and Cyp2a5 gene expression. Phorone, an Nrf2 activator, strongly increased Cyp2b10 and Cyp2a5 mRNA as well as Nrf2 target genes, including NAD(P)H-quinone oxidoreductase-1 and heme oxygenase-1, in wild-type mouse livers 8 h after treatment. The phorone-induced mRNA levels in Nrf2(-⧸-) mouse livers were lower than that in wild-type mouse livers. Nrf2(-⧸-) mice showed attenuated Cyp2b10 and Cyp2a5 induction by phenobarbital, a classical Cyp2b inducer. These findings suggest that the Nrf2 pathway is involved in Cyp2b10 and Cyp2a5 gene expression.

Keywords: ARE, antioxidant response element; CAR, constitutive androstane receptor; Cyp2a5; Cyp2b10; Gapdh, glyceraldehyde-3-phosphate dehydrogenase; Hmox1, heme oxygenase-1; Maf, musculoaponeurotic fibrosarcoma oncogene homolog; Mouse; Nqo1, NAD(P)H-quinone oxidoreductase-1; Nrf2, nuclear-factor erythroid 2-related factor 2; Nuclear-factor erythroid 2-related factor 2; P450, cytochrome P450; PBREM, phenobarbital responsive element module; PCR, polymerase chain reaction; Phenobarbital; Phorone.

Graphical abstract

Fig. 1

The effects of phorone on Nqo1 and Hmox1 gene expression in mouse livers. (A) Structure of phorone. (B and C) Mice were injected intraperitoneally with phorone or corn oil, and their livers were excised at the times indicated. The mRNA levels were determined by real-time PCR and semiquantified by normalizing to Gapdh mRNA. Values represent the mean±S.E.M. (n=3). The significant difference was assessed by the Kruskal–Wallis non-parametric analysis followed by the Dunnett test. ^⁎P<0.05 vs. control mice.

Fig. 2

The effects of phorone on P450 gene expression in mouse livers. Mice were injected intraperitoneally with phorone or corn oil, and their livers were excised at the times indicated. The mRNA levels were determined by real-time PCR and semiquantified by normalizing to Gapdh mRNA. Values represent the mean±S.E.M. (n=3). The significant difference was assessed by the Kruskal–Wallis non-parametric analysis followed by the Dunnett test. ^⁎P<0.05 vs. control mice.

Fig. 3

Phorone suppressed the induction of Cyp2b10, Cyp2a5, and Nqo1 mRNA in Nrf2^−⧸− mouse livers. (A–C) Mice were injected intraperitoneally with phorone or corn oil, and their livers were excised 8 h after treatment. The mRNA levels were determined by real-time PCR and semiquantified by normalizing to Gapdh mRNA. Values represent the mean±S.E.M. (n=4–5). The significant difference was assessed by the Kruskal–Wallis non-parametric analysis followed by the Scheffé test (^⁎P<0.05, ^⁎⁎P<0.01 and ^⁎⁎⁎P<0.001).

Fig. 4

Nrf2 is involved in phenobarbital-induced Cyp2b10, Cyp2a5, and Nqo1 gene expression in mouse livers. (A) Structure of phenobarbital. (B–D) Mice were injected intraperitoneally with phenobarbital or saline, and their livers were excised 12 h after treatment. The mRNA levels were determined by real-time PCR and semiquantified by normalizing to Gapdh mRNA. Values represent the mean±S.E.M. (n=3–6). The significant difference was assessed by the Kruskal–Wallis non-parametric analysis followed by the Scheffé test (⁎P<0.05).