Tydén E, Löfgren M, Pegolo S, Capolongo F, Tjälve H, Larsson P
Department of Biomedical Sciences and Veterinary Public Health, Division of Pathology, Pharmacology and Toxicology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
J Vet Pharmacol Ther. 2012 Dec;35(6):588-95. doi: 10.1111/j.1365-2885.2012.01379.x. Epub 2012 Jan 29.
Recently, seven CYP3A isoforms - CYP3A89, CYP3A93, CYP3A94, CYP3A95, CYP3A96, CYP3A97 and CYP129 - have been isolated from the horse genome. In this study, we have examined the hepatic and intestinal gene expression of these CYP3A isoforms using TaqMan probes. We have also studied the enzyme activity using luciferin-isopropyl acetal (LIPA) as a substrate. The results show a differential gene expression of the CYP3A isoforms in the liver and intestines in horses. In the liver, CYP3A89, CYP3A94, CYP3A96 and CYP3A97 were highly expressed, while in the intestine there were only two dominating isoforms, CYP3A93 and CYP3A96. The isoform CYP3A129 was not detected in the liver or the intestine, although this gene consists of a complete set of exons and should therefore code for a functional protein. It is possible that this gene is expressed in tissues other than the liver and intestines. In the intestine, both CYP3A96 and CYP3A93 showed the highest gene expression in the duodenum and the proximal parts of the jejunum. This correlated with a high protein expression in these tissues. Studies of the enzyme activity showed the same K(m) for the LIPA substrate in the liver and the intestine, while the maximum velocity (V(max)) in the liver was higher than in the intestine. Our finding of a differential gene expression of the CYP3A isoforms in the liver and the intestines contributes to a better understanding of drug metabolism in horses.
最近，从马基因组中分离出了7种CYP3A亚型——CYP3A89、CYP3A93、CYP3A94、CYP3A95、CYP3A96、CYP3A97和CYP129。在本研究中，我们使用TaqMan探针检测了这些CYP3A亚型在肝脏和肠道中的基因表达。我们还以荧光素异丙醇缩醛（LIPA）为底物研究了酶活性。结果显示，马肝脏和肠道中CYP3A亚型的基因表达存在差异。在肝脏中，CYP3A89、CYP3A94、CYP3A96和CYP3A97高表达，而在肠道中只有两种主要亚型，即CYP3A93和CYP3A96。尽管CYP3A129基因包含完整的外显子集，因此应该编码一种功能性蛋白质，但在肝脏或肠道中未检测到该亚型。该基因有可能在肝脏和肠道以外的组织中表达。在肠道中，CYP3A96和CYP3A93在十二指肠和空肠近端的基因表达最高。这与这些组织中的高蛋白表达相关。酶活性研究表明，肝脏和肠道中LIPA底物的米氏常数（K(m)）相同，而肝脏中的最大反应速度（V(max)）高于肠道。我们发现肝脏和肠道中CYP3A亚型的基因表达存在差异，这有助于更好地理解马的药物代谢。
