Analysis of human fetus-specific cytochrome P450 : Evaluation of its function (s) by using transgenic mice and estimation of regulation mechnism (S).

点击翻译按钮获取中文摘要

The human fetus-specific P450, CYP3A7, was expressed in C57BL/6N mice by microinjection into the mouse fertilized eggs of a CYP3A7 cDNA fused to a murine metallothionein-I promoter. Six transgenic lines of mice carrying different copies of the MT-I-CYP3A7 transgene were established. In M10 line of mice, the expression of the CYP3A7 at mRNA and/or protein levels were detected in the liver, testis, and other tissues, while in M2 line of mice the expression of CYP3A7 was found in the kiney and many other tissues. The expression of the CYP3A7 was induced by the treatment with zinc sulfate, an inducer of MT-I promoter. The CYP3A7 was expressed perinatally in the M10 mice, beginning on the day 15 of gestation. The expression level was low in fetal life and increased markedly in the livers of neonates 3 days after birth. The CYP3A7 protein expressed in the livers of M10 neonates as well as in the adults was functionally active in terms of midazolam 1'-hydroxylation in vivo. Using M2 and M10 mice as an animal model, the involvement of human CYP3A7 in the bioactivation of AFB_1 in vivo was further evidenced by a significantly higher AFB1-N^7-Guanine adduct level as well as DNA damage in the liver and kidney of M10 and M2 mice, respectively. These give the first evidence that human CYP3A7 plays a role in the bioactivation of AFB_1 in vivo. This transgenic animal model is the first to carry a human P450 gene and provides the first successful example of assessing a human P450 gene in rodent by transgenic technique.