Key Laboratory of Systems Biomedicine (Ministry of Education), Center for Comparative Biomedicine, Institute of Systems Biomedicine, and State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, School of Medicine, and Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Bio-X Center, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
Key Laboratory of Systems Biomedicine (Ministry of Education), Center for Comparative Biomedicine, Institute of Systems Biomedicine, and State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, School of Medicine, and Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Bio-X Center, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
Mol Pharmacol. 2014 Jul;86(1):62-75. doi: 10.1124/mol.113.091462. Epub 2014 Apr 11.
The zebrafish genome contains a gene superfamily of 40 Ugt genes that can be divided into Ugt1, Ugt2, and Ugt5 families. Because the encoded zebrafish UDP glucuronosyltransferase (UGT) proteins do not display orthologous relationships to any of the mammalian and avian UGT enzymes based on molecular phylogeny, it is difficult to predict their substrate specificity. Here, we mapped their tissue-specific expression patterns. We showed that the zebrafish UGT enzymes can be glycosylated. We determined their substrate specificity and catalytic activity toward diverse aglycone substrates. Specifically, we measured mRNA levels of each of the 40 zebrafish Ugt genes in 11 adult tissues and found that they are expressed in a tissue-specific manner. Moreover, functional analyses with the donor of UDP glucuronic acid (UDPGA) for each of the 40 zebrafish UGT proteins revealed their substrate specificity toward 10 important aglycones. In particular, UGT1A1, UGT1A7, and UGT1B1 displayed good glucuronidation activities toward most phenolic aglycones (4-methylumbelliferone, 4-nitrophenol, 1-naphthol, bisphenol A, and mycophenolic acid) and the two carboxylic acids (bilirubin and diclofenac). Importantly, some members of the UGT5, a novel UGT family identified recently, are capable of glucuronidating multiple aglycones with the donor cofactor of UDPGA. In particular, UGT5A5, UGT5B2, and UGT5E1 glucuronidate phenols and steroids with high specificity toward steroid hormones of estradiol and testosterone and estrogenic alkylphenols 4-tert-octylphenol. These results shed new insights into the mechanisms by which fish species defend themselves against vast numbers of xenobiotics via glucuronidation conjugations and may facilitate the establishment of zebrafish as a model vertebrate in toxicological, developmental, and pathologic studies.
斑马鱼基因组包含一个 40 个 Ugt 基因的基因超家族，可分为 Ugt1、Ugt2 和 Ugt5 家族。由于基于分子系统发生学，编码的斑马鱼 UDP 葡糖醛酸基转移酶（UGT）蛋白与任何哺乳动物和禽类 UGT 酶都没有同源关系，因此很难预测其底物特异性。在这里，我们绘制了它们的组织特异性表达模式。我们表明，斑马鱼 UGT 酶可以被糖基化。我们确定了它们对各种非糖基化底物的底物特异性和催化活性。具体来说，我们测量了 11 种成年组织中 40 种斑马鱼 Ugt 基因中的每一种的 mRNA 水平，发现它们以组织特异性方式表达。此外，对 40 种斑马鱼 UGT 蛋白中的每一种的 UDP 葡萄糖醛酸（UDPGA）供体进行功能分析，揭示了它们对 10 种重要非糖基化底物的底物特异性。特别是，UGT1A1、UGT1A7 和 UGT1B1 对大多数酚类非糖基化底物（4-甲基伞形酮、4-硝基苯酚、1-萘酚、双酚 A 和霉酚酸）和两种羧酸（胆红素和双氯芬酸）具有良好的葡萄糖醛酸化活性。重要的是，最近发现的新型 UGT 家族 UGT5 的一些成员能够利用 UDPGA 供体糖基化多种非糖基化底物。特别是，UGT5A5、UGT5B2 和 UGT5E1 对甾体激素雌二醇和睾酮以及雌激素烷基酚 4-叔辛基苯酚具有高度特异性地葡萄糖醛酸化酚类和甾体。这些结果为鱼类通过葡萄糖醛酸化缀合来保护自身免受大量外源性化学物质的侵害的机制提供了新的见解，并可能促进斑马鱼作为毒理学、发育和病理研究中模型脊椎动物的建立。
