Relationship of human liver dihydrodiol dehydrogenases to hepatic bile-acid-binding protein and an oxidoreductase of human colon cells

Abstract

We previously isolated three monomeric dihydrodiol dehydrogenases, DD1, DD2 and DD4, from human liver, and cloned a cDNA (C9) thought to encode DD2, which is identical with those for human bile-acid-binding protein and an oxidoreductase of human colon carcinoma HT29 cells. In the present study we have provided evidence that the C9 cDNA clone encodes DD1, not DD2. A recombinant enzyme expressed from the cDNA in a bacterial system was purified, and its catalytic properties, bile-acid-binding ability and primary sequence were compared with those of the hepatic dihydrodiol dehydrogenases. The results show that DD1 encoded by C9 possesses prostaglandin F synthase activity but low affinity for lithocholic acid, whereas DD2, showing differences of six amino acid residues from the DD1 sequence, exhibited high-affinity binding for the bile acid. Refined relationship between dihydrodiol dehydrogenases and their related proteins of human tissues is proposed.

Close kinship of human 20α‐hydroxysteroid dehydrogenase gene with three aldo‐keto reductase genes

“…Table 2 clearly shows that only 20a-HSD had the 20a-HSD activity, showing high kcat/Km values with their substrates, such as progesterone, 20a-OHP, pregnanolone and pregnandiol. This coincides with previous results (Hara et al 1996), which demonstrated that recombinant 20a-HSD shows an oxidation activity of 20a-OHP and pregnandiol, and their kinetic constants are similar to the values in Table 2. In addition to this, 20a-HSD had a weak PGE 2 9-ketoreductase activity to convert PGE 2 to PGF 2a .…”

“…Surprisingly, BABP did not have a 20a-HSD activity, and showed no or little enzymatic activities with the substrates, except for the synthetic substrates 1-acenaphthenol and (S)-( )-1-indanol. The activities to oxidize these synthetic substrates were inhibited by bile acids (data not shown), similarly to the previous report with BABP puri®ed from the liver (Hara et al 1996). On the other hand, PGFS shows prominent PGD 2 11-ketoreductase activity to reduce PGD 2 and to oxidize 9a, 11b-PGF 2 (Matsuura et al 1998;Suzuki-Yamamoto et al 1999).…”

“…In the present study, cDNAs encoding 20a-HSD, BABP and DD4 were cloned. Sequences encoding these 20a-HSD, BABP, PGFS and DD4 cDNAs completely matched our exon sequences, as well as those of reported cDNA sequences (Winters et al 1990;Qin et al 1993;Hara et al 1996;SuzukiYamamoto et al 1999) at an amino acid level, and almost identical at a nucleotide level except for a few silent base changes. Then, 20a-HSD, BABP and DD4 were expressed in bacteria and subjected to kinetic analysis in the presence of the cofactor NADPH or NADP to compare substrate speci®city.…”

“…This recombinant enzyme has mainly 17b-HSD activity to metabolize oestrogens and androgens, and also catalyses the one-way reaction from 20a-OHP to progesterone. Thereafter, cDNA encoding a cytosolic enzyme dihydrodiol dehydrogenase (DD) 1 in human liver was cloned and recently identi®ed as human 20a-HSD [AKR 1C1] cDNA (Stolz et al 1993;Deyashiki et al 1994;Hara et al 1996). This 323 amino acid residue-protein has 80% and 69% amino acid identity to rabbit and rat 20a-HSDs, respectively.…”

An indomethacin analogue, N-(4-chlorobenzoyl)-melatonin, is a selective inhibitor of aldo-keto reductase 1C3 (type 2 3α-HSD, type 5 17β-HSD, and prostaglandin F synthase), a potential target for the treatment of hormone dependent and hormone independent malignancies

“…Indomethacin methyl ester, which could only be tested up to 20 μM because its UV absorbance interfered with the assay at higher concentrations, effectively inhibited only AKR1C3 and had no effect on PQ reduction by the other AKR1C enzymes at the concentrations tested. Previously, Matsuura et al [10] had shown that indomethacin had high affinity for AKR1C3, while Hara et al [26] showed that indomethacin was a relatively weak inhibitor of AKR1C1 and AKR1C2. However, these studies used widely varied concentrations of substrate relative to the K M of the respective enzymes, making the results difficult to compare across isoform.…”