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Molecular characterization of two monkey dihydrodiol dehydrogenases
Yu Higaki1, Takeshi Kamiya, Noriyuki Usami
1Laboratory of Biochemistry, Gifu Pharmaceutical University, Mitahora-higashi, Japan.
Drug Metabolism and Pharmacokinetics
|December 25, 2004
Summary
Researchers identified and purified two forms of dihydrodiol dehydrogenase (DD1 and DD4) in monkey liver. These enzymes are homologous to human AKR1C1 and AKR1C4, with distinct tissue expression patterns suggesting differences in steroid metabolism between monkeys and humans.
Area of Science:
- Biochemistry
- Enzymology
- Comparative genomics
Background:
- Japanese monkey liver possesses multiple dihydrodiol dehydrogenase (DD) forms with 3(20)α-hydroxysteroid dehydrogenase activity.
- Understanding these enzymes is crucial for comparative studies in steroid and xenobiotic metabolism.
Purpose of the Study:
- To purify and characterize major (DD1) and minor (DD4) dihydrodiol dehydrogenase forms from Cynomolgus monkey liver.
- To isolate and analyze the corresponding cDNA sequences for DD1 and DD4 in both Cynomolgus and Japanese monkeys.
- To compare the identified monkey enzymes with human 3(20)α-hydroxysteroid dehydrogenase isoenzymes.
Main Methods:
- Purification of DD1 and DD4 from Cynomolgus monkey liver.
- Isolation of cDNA species via reverse transcription-PCR.
- Amino acid sequence analysis and comparison with human isoenzymes.
- Analysis of substrate specificity and inhibitor sensitivity of recombinant enzymes.
- Tissue-specific mRNA expression profiling using Northern blot analysis.
Main Results:
- Purified DD1 and DD4 from Cynomolgus monkey liver; isolated cDNAs encoding 323-amino acid proteins with 83% sequence identity.
- Monkey DD1 and DD4 showed high sequence identity (94%) to human AKR1C1 and AKR1C4, respectively, functioning as functional homologues.
- DD1 mRNA was found in liver, kidney, intestine, and adrenal gland; DD4 mRNA was detected in liver and kidney of Japanese monkeys.
- Tissue distribution patterns for monkey DD1 and DD4 differed significantly from ubiquitously expressed human AKR1C1 and liver-specific human AKR1C4.
- No mRNA corresponding to human AKR1C2 was detected in the studied monkey livers.
Conclusions:
- Monkey DD1 and DD4 are functional homologues of human AKR1C1 and AKR1C4, respectively.
- Distinct tissue expression patterns of these enzymes in monkeys compared to humans suggest species-specific regulation of steroid and xenobiotic metabolism.
- Further research is warranted to elucidate the precise roles and regulatory mechanisms of these isoenzymes in different species.