Cited by 23Steroid Chemistry and BiochemistryHormonal and reproductive studiesAdrenal Hormones and Disorders

Androgenic 17 beta-hydroxysteroid dehydrogenase activity of expressed rat type I 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase

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de Launoit, Y, Simard, J, Durocher, F, Labrie, F·1992·Endocrinology

Abstract

Transient expression in nonsteroidogenic mammalian cells of the rat wild type I and type II 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase (3 beta-HSD) cDNAs shows that the encoded proteins, in addition to being able to catalyze the oxidation and isomerization of delta 5-3 beta-hydroxysteroid precursors into the corresponding delta 4-3-ketosteroids, interconvert 5 alpha-dihydrotestosterone (DHT) and 5 alpha-androstane-3 beta,17 beta-diol (3 beta-diol). When homogenate from cells transfected with a plasmid vector containing type I 3 beta-HSD is incubated in the presence of DHT using NAD+ as cofactor, a somewhat unexpected metabolite is formed, namely 5 alpha-androstanedione (A-dione), thus indicating an intrinsic androgenic 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity of this 3 beta-HSD isoform. Although the relative Vmax of 17 beta-HSD activity is 14.9-fold lower than that of 3 beta-HSD activity, the Km value for the 17 beta-HSD activity of type I 3 beta-HSD is 7.97 microM, a value which is in the same range as the conversion of DHT into 3 beta-diol which shows a Km value of 4.02 microM. Interestingly, this 17 beta-HSD activity is highly predominant in unbroken cells in culture, thus supporting the physiological relevance of this "secondary" activity. Such 17 beta-HSD activity is inhibited by the classical substrates of 3 beta-HSD, namely pregnenolone (PREG), dehydroepiandrosterone (DHEA), delta 5-androstene-3 beta,17 beta-diol (delta 5-diol), 5 alpha-androstane-3 beta,17 beta-diol (3 beta-diol) and DHT, with IC50 values of 2.7, 1.0, 3.2, 6.2, and 6.3 microM, respectively. Although dual enzymatic activities have been previously reported for purified preparations of other steroidogenic enzymes, the present data demonstrate the multifunctional enzymatic activities associated with a recombinant oxidoreductase enzyme. In addition to its well known 3 beta-HSD activity, this enzyme possesses the ability to catalyze DHT into A-dione thus potentially controlling the level of the active androgen DHT in classical steroidogenic as well as peripheral intracrine tissues.

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Crossref · 10.1210/endo.130.1.1309351

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  • Enzyme isoforms vary greatly between species, so care should be taken when using animal models to study intracrinology.

    “It should again be noted that care should be taken when using animal models to study intracrinology as the enzyme isoforms vary greatly between species.”

    From Intracrine androgen biosynthesis, metabolism and action revisited (2018) · cites this paper as de Launoit et al., 1992

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Authors
de Launoit, Y., Simard, J., Durocher, F., & Labrie, F.
Affiliations
Centre de recherche du CHU de Québec-Université Laval (CA)
Venue
Endocrinology
Published
1992-01
Volume
130
Issue
1
Pages
553-555
ISSN
  • 0013-7227 (ISSN-L)
  • 1945-7170
OpenAlex
W2097430076
Cited by
23
References
0
Citations by year
2017: 1 · 2012: 1
FWCI
1.45
Type
journal article
Language
en
Open access
Licence
other-oa
Locations
  • Endocrinology (publishedVersion)
  • PubMed (publishedVersion)
  • Dépôt institutionnel de l'Université libre de Bruxelles (Université Libre de Bruxelles) (submittedVersion, other-oa)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Steroid Chemistry and Biochemistry
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Hormonal and reproductive studies
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Adrenal Hormones and Disorders
Keywords
17β-hydroxysteroid dehydrogenase, dihydrotestosterone, steroid metabolism, enzyme inhibition, transient transfection
MeSH terms
Animals, HeLa Cells, Humans, Isoenzymes, Kinetics, Multienzyme Complexes, Progesterone Reductase, Steroid Isomerases, Transfection, 17-Hydroxysteroid Dehydrogenases, Rats

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