Zhang Qing-Yu, Dunbar Debbie, Kaminsky Laurence S
New York State Department of Health, Wadsworth Center, P.O. Box 509, Albany, NY 12201-0509, USA.
Drug Metab Dispos. 2003 Nov;31(11):1346-51. doi: 10.1124/dmd.31.11.1346.
The expression of biotransformation enzymes in mouse small intestine is poorly characterized, which limits the utility of transgenic or knockout mouse models for first-pass drug metabolism studies. In response, we have systematically examined the composition and inducibility of cytochrome P450 (P450) protein and mRNA in mouse small intestinal epithelial cells (enterocytes). RNA-PCR was conducted to confirm the expression and identity of CYP1A1, 1B1, 2B10, 2B19, 2B20, 2C29, 2C38, 2C40, 2E1, 3A11, 3A13, 3A16, 3A25, and 3A44 in the enterocytes of untreated mice, but CYP1A2, 2A4/5, 2A12, 2C37, 2C39, and 2F2 were not detected. The inducibility of CYP2B, 2C, and 3A subfamily forms was determined by real-time quantitative RNA-PCR. All five CYP3A forms were induced, in a range from 1.7- to 4.5-fold, by dexamethasone (DEX). Phenobarbital (PB) induced CYP2B9, CYP2B10, and CYP2B20 mRNAs and suppressed CYP2B19 mRNA levels. PB also induced CYP2C29 and CYP2C40, but not CYP2C38 mRNA. At the protein level, CYP1A1, CYP1B1, CYP2B, CYP2C, CYP2E1, and CYP3A were detected in enterocytes from untreated mice by immunoblot analysis. CYP1A1 was inducible by beta-naphthoflavone (BNF), CYP2B and CYP2C by PB, and CYP3A by DEX. CYP2B, 2C, and 3A proteins were all expressed at high levels proximally, and decreased distally. The inducibility of CYP1A1 followed a similar pattern. Intestinal P450 expression was compared between C57BL/6 (B6) and 129/sv (129) mice, strains commonly used in the preparation of transgenic and knockout mouse models. There was no significant strain difference in constitutive levels or induction patterns for CYP2B, 2C, and 3A protein. However, CYP1A1 was induced to a high level by BNF in B6 mice, but was not induced in the 129 mice.
小鼠小肠中生物转化酶的表达情况鲜为人知，这限制了转基因或基因敲除小鼠模型在首过药物代谢研究中的应用。为此，我们系统地研究了小鼠小肠上皮细胞（肠细胞）中细胞色素P450（P450）蛋白和mRNA的组成及诱导性。采用RNA-PCR法确认未处理小鼠肠细胞中CYP1A1、1B1、2B10、2B19、2B20、2C29、2C38、2C40、2E1、3A11、3A13、3A16、3A25和3A44的表达及特性，但未检测到CYP1A2、2A4/5、2A12、2C37、2C39和2F2。通过实时定量RNA-PCR法测定CYP2B、2C和3A亚家族形式的诱导性。所有五种CYP3A形式均被地塞米松（DEX）诱导，诱导倍数在1.7至4.5倍之间。苯巴比妥（PB）诱导CYP2B9、CYP2B10和CYP2B20的mRNA表达，并抑制CYP2B19的mRNA水平。PB还诱导CYP2C29和CYP2C40，但不诱导CYP2C38的mRNA。在蛋白水平，通过免疫印迹分析在未处理小鼠的肠细胞中检测到CYP1A1、CYP1B1、CYP2B、CYP2C、CYP2E1和CYP3A。CYP1A1可被β-萘黄酮（BNF）诱导，CYP2B和CYP2C可被PB诱导，CYP3A可被DEX诱导。CYP2B、2C和3A蛋白在近端均高水平表达，在远端表达降低。CYP1A1的诱导性呈现类似模式。比较了常用于制备转基因和基因敲除小鼠模型的C57BL/6（B6）和129/sv（129）小鼠之间的肠道P450表达。CYP2B、2C和3A蛋白的组成水平或诱导模式在品系间无显著差异。然而，BNF可使B6小鼠的CYP1A1诱导至高水平，但在129小鼠中未诱导。
