National Center for Aquatic Pathogen Collection, College of Fisheries and Life Science, Shanghai Ocean University, 999 Hucheng Huan Road, Shanghai 201306, China.
Environ Toxicol Pharmacol. 2011 Mar;31(2):307-13. doi: 10.1016/j.etap.2010.11.009. Epub 2010 Nov 27.
Cytochrome P450s (CYPs) play a prominent role in drug metabolism and biotransformation which are distributed in liver of aquatic animals. However, limited information is available about CYP genes involved in drug metabolism in fish. In the present study, we explore CYP1A characterization for DIF metabolism. Firstly, we cloned and characterized the full-length cDNA sequence of a CYP1A gene from crucian carp (hybridized Prussian carp), the predicted protein sequence for CYP1A comprise 496 amino acids. The heme-binding region of the CYP1A, encompassing the amino acid sequence GLGKRRCIG, which is identical to the same region of other homologues. Secondly, we studied the difloxacin (DIF) kinetics and the effects of DIF on their corresponding CYP1A mRNA levels in liver of crucian carp. CYP1A1 mRNA expression was analyzed by real-time PCR, and DIF concentration was determined by reversed-phase high-performance liquid chromatography (RP-HPLC). Results showed that the concentration of DIF in liver reached its peak (67.70 mg kg(-1)) at 0.5h, while the CYP1A1 gene expression was at the lowest point. CYP1A mRNA was down-regulated by 6.5 mg ml(-1) DIF in the liver of crucian carp. Thus, our work confirmed that DIF is both the substrate and inhibitor of CYP1A. The information provided a model for the potential utility of gene expression analysis and drug metabolization in fish.
细胞色素 P450s（CYPs）在药物代谢和生物转化中发挥着重要作用，这些酶分布在水生动物的肝脏中。然而，关于鱼类中参与药物代谢的 CYP 基因的信息有限。在本研究中，我们探索了 CYP1A 在 DIF 代谢中的特征。首先，我们从鲫鱼（杂交鲤鱼）中克隆并鉴定了 CYP1A 全长 cDNA 序列，预测的 CYP1A 蛋白序列由 496 个氨基酸组成。CYP1A 的血红素结合区域，包含氨基酸序列 GLGKRRCIG，与其他同源物的同一区域相同。其次，我们研究了 difloxacin（DIF）在鲫鱼肝脏中的动力学和对其相应 CYP1A mRNA 水平的影响。通过实时 PCR 分析 CYP1A1 mRNA 的表达，并通过反相高效液相色谱法（RP-HPLC）测定 DIF 的浓度。结果表明，DIF 在肝脏中的浓度在 0.5 小时达到峰值（67.70mgkg(-1)），而 CYP1A1 基因表达处于最低水平。6.5mgml(-1)的 DIF 可在鲫鱼肝脏中下调 CYP1A mRNA。因此，我们的工作证实 DIF 既是 CYP1A 的底物又是抑制剂。该信息为鱼类中基因表达分析和药物代谢的潜在应用提供了模型。
