Molecular Cloning and Sequencing of Mouse Hepatic 11ß-Hydroxysteroid Dehydrogenase/Carbonyl Reductase. In: Weiner H, Holmes RS, Wermuth B, editors. Enzymology and Molecular Biology of Carbonyl Metabolism 5. Boston: Springer US; 1995. pp. 211-21. [DOI: 10.1007/978-1-4615-1965-2_27]

Carbonyl Reductases and Pluripotent Hydroxysteroid Dehydrogenases of the Short-chain Dehydrogenase/reductase Superfamily

Carbonyl reduction of aldehydes, ketones, and quinones to their corresponding hydroxy derivatives plays an important role in the phase I metabolism of many endogenous (biogenic aldehydes, steroids, prostaglandins, reactive lipid peroxidation products) and xenobiotic (pharmacologic drugs, carcinogens, toxicants) compounds. Carbonyl-reducing enzymes are grouped into two large protein superfamilies: the aldo-keto reductases (AKR) and the short-chain dehydrogenases/reductases (SDR). Whereas aldehyde reductase and aldose reductase are AKRs, several forms of carbonyl reductase belong to the SDRs. In addition, there exist a variety of pluripotent hydroxysteroid dehydrogenases (HSDs) of both superfamilies that specifically catalyze the oxidoreduction at different positions of the steroid nucleus and also catalyze, rather nonspecifically, the reductive metabolism of a great number of nonsteroidal carbonyl compounds. The present review summarizes recent findings on carbonyl reductases and pluripotent HSDs of the SDR protein superfamily.

Carbonyl reductase

Carbonyl reductase (secondary-alcohol:NADP(+) oxidoreductase, EC 1.1. 1.184) belongs to the family of short chain dehydrogenases/reductases (SDR). Carbonyl reductases (CBRs) are NADPH-dependent, mostly monomeric, cytosolic enzymes with broad substrate specificity for many endogenous and xenobiotic carbonyl compounds. They catalyze the reduction of endogenous prostaglandins, steroids, and other aliphatic aldehydes and ketones. They also reduce a wide variety of xenobiotic quinones derived from polycyclic aromatic hydrocarbons. CBR reduces the anthracycline anticancer drugs, daunorubicin(dn) and doxorubicin (dox) to their C-13 hydroxy metabolites, changing the pharmacological properties of these drugs. Emerging data on CBRs over the last several years is generating new insights on the potential involvement of CBRs in a variety of cellular and molecular reactions associated with drug metabolism, detoxication, drug resistance, mutagenesis, and carcinogenesis.

Ovine 11 beta-hydroxysteroid dehydrogenase type 2 gene predicts a protein distinct from that deduced by the cloned kidney cDNA at the C-terminus

The gene encoding ovine 11 beta-hydroxysteroid dehydrogenase type 2 (11 beta-HSD2) was cloned and characterized. This gene consists of five exons and is greater than 4 kb in length. It contains an open reading frame of 1215 bp, which encodes a protein of 404 amino acids with a predicted MW of 44 kDa. The deduced ovine 11 beta-HSD2 protein displays over 78% sequence identity to those of the human, rabbit, rat, and mouse. However, this differs from the published sequence of ovine kidney 11 beta-HSD2 cDNA which predicts a protein of 427 amino acids. Sequence alignment indicated that this discrepancy is attributed to two single nucleotide omissions in the published cDNA sequence which resulted in a shift in the open reading frame at the codon for residue 358. Therefore, the present results have provided conclusive evidence that the primary structure of 11 beta-HSD2 protein is well conserved between the sheep and the other four mammals. Moreover, Northern blot analysis of total RNA samples from 15 peripheral tissues and seven brain regions of the mature fetal sheep revealed that the expression of 11 beta-HSD2 gene is highly tissue-specific in that it is only expressed in the kidney and adrenal gland, and at a much lower abundance in the testis, colon and placenta. The cloning of the sheep 11 beta-HSD2 gene should facilitate future studies on the regulation of 11 beta-HSD2 gene expression during fetal development in a mammalian model.