Functional characterization of human and cynomolgus monkey UDP-glucuronosyltransferase 1A1 enzymes

Nobumitsu Hanioka, Natsuko Tanabe, Hideto Jinno, Toshiko Tanaka-Kagawa, Kenjiro Nagaoka, Shinsaku Naito, Akiko Koeda, Shizuo Narimatsu

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


Aims: UDP-glucuronosyltransferase 1A1 (UGT1A1) plays important roles in the glucuronidation of various drugs and endogenous substances. Cynomolgus monkeys are regarded as experimental animals closer to humans in studies on safety evaluation and biotransformation for drug development. In this study, the similarities and differences in the enzymatic properties of UGT1A1 between humans and cynomolgus monkeys were precisely identified. Main methods: Human and cynomolgus monkey UGT1A1s (humUGT1A1 and monUGT1A1, respectively) were cloned, and the corresponding proteins were heterologously expressed in insect cells. The enzymatic properties of UGT1A1 proteins were characterized by kinetic analysis of 7-hydroxy-4-trifluoromethylcoumarin (7-HFC), estradiol at 3-hydroxy position (E-3OH) and 7-ethyl-10-hydroxycamptothecin (SN-38) glucuronidation. Key findings: There were no significant differences in the levels of kinetic parameters for 7-HFC, E-3OH and SN-38 glucuronidation between humans and cynomolgus monkeys in both enzyme sources of liver microsomes and recombinant UGT1A1s. 7-HFC and E-3OH glucuronidation by human liver microsomes exhibited biphasic and sigmoidal kinetics, respectively, whereas the kinetics by cynomolgus monkey liver microsomes fitted the typical Michaelis-Menten model. SN-38 glucuronidation by human and cynomolgus monkey liver microsomes exhibited autoactivation kinetics. In recombinant UGT1A1 enzymes expressed in insect cells, the kinetics of 7-HFC, E-3OH and SN-38 glucuronidation fitted the substrate inhibition (7-HFC glucuronidation) or Hill equation (E-3OH and SN-38 glucuronidation), and each glucuronidation showed the same kinetic profile between humans and cynomolgus monkeys. Significance: These findings suggest that the enzymatic properties of human and cynomolgus monkey UGT1A1 enzymes are very similar.

Original languageEnglish
Pages (from-to)261-268
Number of pages8
JournalLife Sciences
Issue number7-8
Publication statusPublished - Aug 2010
Externally publishedYes


  • 7-Ethyl-10-hydroxycamptothecin (SN-38)
  • 7-Hydroxy-4-trifluoromethylcoumarin (7-HFC)
  • Cynomolgus monkey
  • Estradiol at 3-hydroxy position (E-3OH)
  • Human
  • UDP-glucuronosyltransferase (UGT)
  • UGT1A1

ASJC Scopus subject areas

  • General Pharmacology, Toxicology and Pharmaceutics
  • General Biochemistry,Genetics and Molecular Biology


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