PUBLICATION

Characterization of the Zebrafish Ugt Repertoire Reveals a New Class of Drug-metabolizing UDP Glucuronosyltransferases

Authors
Wang, Y., Huang, H., Wu, Q.
ID
ZDB-PUB-140513-150
Date
2014
Source
Molecular pharmacology   86(1): 62-75 (Journal)
Registered Authors
Keywords
Phase II enzymes, UDP-glucuronyltransferases
MeSH Terms
  • Animals
  • Catalysis
  • Estradiol/metabolism
  • Glucuronosyltransferase/genetics*
  • Glucuronosyltransferase/metabolism*
  • Inactivation, Metabolic/genetics*
  • Phenols/metabolism
  • RNA, Messenger/genetics
  • Substrate Specificity/genetics
  • Testosterone/metabolism
  • Uridine Diphosphate Glucuronic Acid/genetics
  • Uridine Diphosphate Glucuronic Acid/metabolism
  • Xenobiotics/pharmacology
  • Zebrafish/genetics*
  • Zebrafish/metabolism*
  • Zebrafish Proteins/genetics*
  • Zebrafish Proteins/metabolism*
PubMed
24728488 Full text @ Mol. Pharmacol.
CTD
24728488
Abstract
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 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 UDPGA for each of the 40 zebrafish UGT proteins revealed their substrate specificity toward ten 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 pathological studies.
Genes / Markers
Figures
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Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Antibodies
Orthology
Engineered Foreign Genes
Mapping