Piscine UDP-glucuronosyltransferase 1B
Piscine UDP-glucuronosyltransferase 1B
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DOI：
10.1016/j.aquatox.2007.06.015
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发表时间：
2007-10-15
影响因子：
4.5
通讯作者：
George, Stephen G.
中科院分区：
文献类型：
--
作者：
Leaver, Michael J.;Wright, Joy;George, Stephen G.
葡萄糖醛酸化是鱼类有机污染物的重要解毒途径。我们在此报告了从密切相关的海洋比目鱼、鲽鱼 (Pleuronectesplatessa) 和比目鱼 (Platichthys flesus) 中分离和鉴定 UDP-葡萄糖醛酸基转移酶 (UGT) 基因。推导的氨基酸序列与哺乳动物 UGT1 家族基因比 UGT2 基因具有更大的相似性（分别为 44-47% 和 39-40% 氨基酸同一性），并被命名为 UGT1B。鲽鱼和比目鱼 UGT1B mRNA 在所有组织中表达，其中在肝脏中表达最高，在肠、鳃、肾脏和脂肪组织中表达量较高，在肌肉、心脏和大脑中表达量较低。鲽 UGT1B mRNA 在配子或受精卵中检测不到，在原肠胚形成和肌节形成之间表达量大幅增加，之后水平下降约 5-10 倍。腹腔注射 Arolor 1254 或林丹（γ-六氯环己烷）后，鲽鱼肝脏中 UGT1B mRNA 增加，但全氟辛酸或 3-甲基胆蒽处理后则没有增加。在分离的牙鲆肝细胞中，暴露于苯并(a)芘后UGT I B mRNA增加，但暴露于17α-乙炔雌二醇则不增加。与类固醇缀合相比，cos7 细胞中鲽 UGT1 B cDNA 的表达导致细胞匀浆中更高的 1-萘酚缀合，而胆红素和胆汁酸缀合则检测不到。这表明鲽基因编码先前在我们实验室从该物种中纯化的苯酚结合UGT，并且它可能在比目鱼多环芳烃的解毒中发挥主要作用。它在发育中的作用尚不清楚。 UGT1B 基因也存在于河豚鱼 (Tetraodon nigroviridis) 和斑马鱼 (Danio rerio) 的基因组中，但它们的基因组织不同。河豚拥有多个（重复的）完整 UGT1 基因，Southern 印迹表明同源鲽鱼 UGT1B 基因也可能以这种方式组织。相比之下，斑马鱼似乎有两个 UGT1 位点，其序列和内含子/外显子结构与鲽鱼的序列和内含子/外显子结构密切相关，然而，这些基因的组织与哺乳动物 UGT1 家族相似，因为每个基因座都有多个重复的外显子 1，这些外显子 1 交替剪接到编码糖苷配基结合域的一组常见外显子上。结合鱼类序列与哺乳动物 UGT1 和 UGT2 家族的系统发育比较的证据，我们建议这些同源鱼类 UGT 应全部包含在脊椎动物 UGT1 家族中，并指定为 UGT1B。 (C) 2007 Elsevier B.V. 保留所有权利。
Glucuronidation is an important detoxification pathway for organic pollutants in fish. We report here the isolation and characterisation of UDP-glucuronosyltransferases (UGT) genes from the closely related marine flatfish, plaice (Pleuronectes platessa) and flounder (Platichthys flesus). The deduced amino acid sequences share greater similarity with mammalian UGT1 family genes than UGT2 genes (44-47% and 39-40% amino acid identity, respectively) and have been designated UGT1B. Both plaice and flounder UGT1B mRNAs are expressed in all tissues and are most highly expressed in liver, with high levels in intestine, gill, kidney and adipose tissue and much lower levels in muscle, heart and brain. Plaice UGT1B mRNA is undetectable in gametes or fertilised eggs and there is a large increase in expression between gastrulation and myotome formation after which levels decline some 5-10-fold. Flounder UGT1B mRNA was increased in liver after intraperitoneal injection of Arochlor 1254 or lindane (gamma-hexachlorocyclohexane), but not after perflourooctanoic acid or 3-methylcholanthrene treatment. In isolated flounder hepatocytes UGT I B mRNA was increased after exposure to benzo(a)pyrene but not by 17 alpha-ethynylestradiol. Expression of a cDNA for plaice UGT1 B in cos7 cells resulted in higher 1-naphthol conjugation in cell homogenates compared to steroid conjugation, whilst bilirubin and bile acid conjugation were undetectable. This indicates that the plaice gene codes for the phenol-conjugating UGT previously purified in our laboratory from this species and that it is likely to play a major role in the detoxification of polyaromatic hydrocarbons in flatfish. Its role in development is unknown. UGT1B genes are also present in pufferfish (Tetraodon nigroviridis) and zebrafish (Danio rerio) genomes, but they differ in their genic organisation. Pufferfish possess multiple (repeated) complete UGT1 genes and Southern blots indicate that the homologous plaice UGT1B gene may also be organised in this way. In contrast, zebrafish appear to have two UGT1 loci whose sequences and intron/exon structures are closely related to that of plaice, however, the organisation of these genes is similar to the mammalian UGT1 family since each has multiple repeated exon 1's which are alternatively spliced to a common set of exons encoding the aglycone binding domain. Taken together with evidence from phylogenetic comparison of fish sequences with UGT1 and UGT2 families in mammals, we suggest these homologous fish UGTs should all be included within the vertebrate UGT1 family and designated as UGT1B. (C) 2007 Elsevier B.V. All rights reserved.