Role of Steroid 11β-Hydroxylase and Steroid 18-Hydroxylase in the Biosynthesis of Glucocorticoids and Mineralocorticoids in Humans

• Published in: Proceedings of the National Academy of Sciences - PNAS 1992-02, Vol.89 (4), p.1458-1462
• Main Authors: Kawamoto, Takeshi, Mitsuuchi, Yasuhiro, Toda, Katsumi, Yokoyama, Yuichi, Miyahara, Karou, Miura, Shigetoshi, Ohnishi, Taira, Ichikawa, Yoshiyuki, Nakao, Kazuwa, Imura, Hiroo, Ulick, Stankey, Shizuta, Yutaka
• Format: Article
• Language: English
• Subjects: 550200 - Biochemistry; ADRENAL HORMONES; Amino Acid Sequence; Analytical, structural and metabolic biochemistry; ANIMALS; Base Sequence; BASIC BIOLOGICAL SCIENCES; Biological and medical sciences; BIOSYNTHESIS; Cercopithecus aethiops; Cloning, Molecular; CORTICOSTEROIDS; Corticosterone; COS cells; DNA SEQUENCING; ENZYME ACTIVITY; ENZYMES; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; GENES; GLUCOCORTICOIDS; Glucocorticoids - biosynthesis; HeLa cells; HORMONES; Humans; HYDROGEN COMPOUNDS; HYDROXY COMPOUNDS; HYDROXYLASES; In Vitro Techniques; KETONES; MAMMALS; MAN; Mineralocorticoids; Mineralocorticoids - biosynthesis; Mitochondria; Mitochondria - enzymology; Molecular Sequence Data; ORGANIC COMPOUNDS; OXIDOREDUCTASES; PREGNANES; PRIMATES; Promoter regions; Promoter Regions, Genetic; PROTEINS; Steroid 11-beta-Hydroxylase - physiology; steroid 18-monooxygenase; STEROID HORMONES; Steroid Hydroxylases - physiology; STEROIDS; STRUCTURAL CHEMICAL ANALYSIS; SYNTHESIS; Terminology as Topic; Transfection; TRITIUM COMPOUNDS; VERTEBRATES
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.89.4.1458

A gene encoding steroid 18-hydroxylase (P-450C18) was isolated from a human genomic DNA library. It was identified as CYP11B2, which was previously postulated to be a pseudogene or a less active gene closely related to CYP11B1, the gene encoding steroid 11β-hydroxylase (P-45011β) [Mornet, E., Dupont, J., Vitek, A. \& White, P. C. (1989) J. Biol. Chem. 264, 20961-20967]. The nucleotide sequence of the promoter region of the P-450C18gene is strikingly different from that of the P-45011βgene, although the sequences of their exons are 93% identical. The transient expression in Y-1 adrenal tumor cells of CAT constructs with a series of deletion mutants of promoter regions of both genes indicated that the two genes are regulated differently. P-450C18as expressed in COS-7 cells exhibits steroid 18-hydroxylase activity to catalyze the synthesis of aldosterone and 18-oxocortisol and exhibits steroid 11β-hydroxylase activity as well. In contrast, P-45011βas expressed in the cultured cells exhibits steroid 11β-hydroxylase activity exclusively but fails to catalyze the synthesis of aldosterone and 18-oxocortisol. These results indicate that P-45011βand P-450C18are products of two different genes and that the former participates in the synthesis of glucocorticoids whereas the latter participates in the synthesis of mineralocorticoids in humans.