IDENTIFICATION OF RIFAMPIN-INDUCIBLE P450IIIA4 (CYP3A4) IN HUMAN SMALL-BOWEL ENTEROCYTES
IDENTIFICATION OF RIFAMPIN-INDUCIBLE P450IIIA4 (CYP3A4) IN HUMAN SMALL-BOWEL ENTEROCYTES
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DOI：
10.1172/jci116064
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发表时间：
1992-11-01
影响因子：
15.9
通讯作者：
WATKINS, PB
中科院分区：
文献类型：
--
作者：
KOLARS, JC;SCHMIEDLINREN, P;WATKINS, PB
P450 IIIA（CYP 3A）亚家族内的酶似乎是某些药物在肠道中显著“首过”代谢的原因。为了鉴定哪些已知的P450 IIIA基因在肠中表达，肠上皮细胞RNA在北方印迹上与合成的寡核苷酸杂交，所述合成的寡核苷酸与肝P450 IIIA 4、P450 IIIA 5和P450 IIIA 7 cDNA的高变区互补。仅用P450 IIIA 4特异性寡核苷酸检测到杂交。通过聚合酶链反应从肠上皮细胞cDNA扩增的DNA片段的直接测序，证实杂交mRNA的身份是P450 IIIA 4。为了确定肠上皮细胞P450 IIIA 4是否是可诱导的，在5名志愿者接受利福平（一种已知的肝脏P450 IIIA 4诱导剂）治疗7天之前和之后，对他们的小肠粘膜进行活检。利福平治疗导致P450 Ⅲ A 4 mRNA的活检浓度平均增加5倍或8倍（P < 0.05），分别以蔗糖酶异麦芽糖酶或肠脂肪酸结合蛋白mRNA的含量进行标准化。利福平也诱导P450 IIIA免疫反应蛋白在肠上皮细胞中的每个科目，判断免疫组织化学，并导致10倍的增加P450 IIIA 4特异性催化活性（红霉素N-去甲基化）在一个病人的研究。我们在肠上皮细胞中鉴定出的诱导型P450 IIIA 4可能部分解释了P450 IIIA 4底物的药物相互作用特征，并提出了一种控制主要类别外源性物质进入体内的策略。
Enzymes within the P450IIIA (CYP3A) subfamily appear to account for significant "first pass" metabolism of some drugs in the intestine. To identify which of the known P450IIIA genes are expressed in intestine, enterocyte RNA was hybridized on Northern blots with synthetic oligonucleotides complementary to hypervariable regions of hepatic P450IIIA4, P450IIIA5, and P450IIIA7 cDNAs. Hybridization was detected only with the P450IIIA4-specific oligonucleotide. The identity of the hybridizing mRNA was confirmed to be P450IIIA4 by direct sequencing of a DNA fragment amplified from enterocyte cDNA by the polymerase chain reaction. To determine if enterocyte P450IIIA4 is inducible, biopsies of small bowel mucosa were obtained from five volunteers before and after they received 7 d of treatment with rifampin, a known inducer of P450IIIA4 in liver. Rifampin treatment resulted in a five- or eightfold mean increase (P < 0.05) in the biopsy concentration of P450IIIA4 mRNA when normalized for content of sucrase isomaltase or intestinal fatty acid binding protein mRNAs, respectively. Rifampin also induced P450IIIA immunoreactive protein in enterocytes in each of the subjects, as judged by immunohistochemistry, and resulted in a 10-fold increase in P450IIIA4-specific catalytic activity (erythromycin N-demethylation) in the one patient studied. Our identification of inducible P450IIIA4 in enterocytes may in part account for drug interactions characteristic of P450IIIA4 substrates and suggests a strategy for controlling entry into the body of a major class of xenobiotics.