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Gene Review

CYP7B1  -  cytochrome P450, family 7, subfamily B,...

Homo sapiens

Synonyms: 25-hydroxycholesterol 7-alpha-hydroxylase, CBAS3, CP7B, Cytochrome P450 7B1, Oxysterol 7-alpha-hydroxylase, ...

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Background to CYP7B1

  • Enzyme activities hydroxylating sterols and steroids on the B ring (6 and 7 positions) were first described biochemically in diverse species; 7-hydroxylation of sterols and steroids is a primordial reaction [1]
  • Cyp7b1 was first identified by Stapelton in mouse as a transcript selectively expressed in the hippocampus [2]
  • The enzyme encoded by mammalian CYP7B1 hydroxylates DHEA, related steroids, and sterols including cholesterol, predominantly at the 7alpha position [3]
  • High-level expression in hippocampus, liver, and other tissues was confirmed by transgenic knock-in [4] and by analysis of human brain tissue [5]
  • Insight into the biological relevance of the Cyp7b1 reaction is provided by the rotational symmetry between substitutions at the 7alpha and 11beta positions and overlap between sterol and steroid (glucocorticoid) signaling [6]

Disease relevance of CYP7B1

High impact information on CYP7B1


  • CYP7B1 and CYP39A1 had no activity toward 4 beta-hydroxycholesterol [10].
  • Hepatic CYP7A1 and CYP7B1 mRNA levels increased several-fold with age [11].
  • Hepatic microsomal 7alpha-hydroxylation of 27-hydroxycholesterol and dehydroepiandrosterone, substrates typical for CYP7B1, increased about 5-fold between infancy and adolescence whereas the activities in kidney microsomes decreased at least 10-fold [11].
  • Transient transfection assays of CYP7B1 promoter/luciferase reporter constructs in HepG2 cells revealed that the promoter was highly active [12].
  • In contrast to the liver-specific expression of CYP7A1, CYP7B1 mRNA transcripts were detected in human tissues involved in steroid genesis (brain, testes, ovary, and prostate) and in bile acid synthesis (liver) and reabsorption (colon, kidney, and small intestine) [12].

Chemical compound and disease context of CYP7B1


Biological context of CYP7B1


Anatomical context of CYP7B1

  • Quantitation of CYP7B1 mRNA in adult and fetal human tissues showed markedly higher CYP7B1 mRNA levels in fetal tissues compared with the corresponding adult ones, except in the liver [13].

Associations of CYP7B1 with chemical compounds

  • The cloned human oxysterol 7alpha-hydroxylase (CYP7B1) cDNA encodes a polypeptide of 506 amino acid residues that shares 40% sequence identity to human cholesterol 7alpha-hydroxylase (CYP7A1), the rate-limiting enzyme in the conversion of cholesterol to bile acids in the liver [12].
  • The current study examines regulation of CYP7B1, a DHEA 7alpha-hydroxylase, by sex hormones [13].
  • In the absence of receptors, 17beta-estradiol suppressed CYP7B1 activity, suggesting that estrogenic effects may be different in cells not expressing receptors [13].
  • The 7alpha-hydroxy-DHEA produced by the cytochrome CYP7B1 in tissues may exert anti-glucocorticoid effects through interference with the 11beta-HSD1-mediated cortisone reduction [14].
  • CYP7B1 was stimulated by synthetic ER agonists but suppressed by 17beta-estradiol and 5alpha-androstane-3beta,17beta-diol in LNCaP cells [8].

Other interactions of CYP7B1


Analytical, diagnostic and therapeutic context of CYP7B1

  • Real-time RT-PCR analysis verified high levels of CYP7B1 mRNA expression in the human CNS [17].


  1. Steroid and sterol 7-hydroxylation: ancient pathways. Lathe, R. Steroids. (2002) [Pubmed]
  2. A novel cytochrome P450 expressed primarily in brain. Stapleton, G., Steel, M., Richardson, M., Mason, J.O., Rose, K.A., Morris, R.G., Lathe, R. J. Biol. Chem. (1995) [Pubmed]
  3. Cyp7b, a novel brain cytochrome P450, catalyzes the synthesis of neurosteroids 7alpha-hydroxy dehydroepiandrosterone and 7alpha-hydroxy pregnenolone. Rose, K.A., Stapleton, G., Dott, K., Kieny, M.P., Best, R., Schwarz, M., Russell, D.W., Björkhem, I., Seckl, J., Lathe, R. Proc. Natl. Acad. Sci. U. S. A. (1997) [Pubmed]
  4. Neurosteroid hydroxylase CYP7B: vivid reporter activity in dentate gyrus of gene-targeted mice and abolition of a widespread pathway of steroid and oxysterol hydroxylation. Rose, K., Allan, A., Gauldie, S., Stapleton, G., Dobbie, L., Dott, K., Martin, C., Wang, L., Hedlund, E., Seckl, J.R., Gustafsson, J.A., Lathe, R. J. Biol. Chem. (2001) [Pubmed]
  5. Dehydroepiandrosterone 7-hydroxylase CYP7B: predominant expression in primate hippocampus and reduced expression in Alzheimer's disease. Yau, J.L., Rasmuson, S., Andrew, R., Graham, M., Noble, J., Olsson, T., Fuchs, E., Lathe, R., Seckl, J.R. Neuroscience. (2003) [Pubmed]
  6. Hexose-6-phosphate dehydrogenase modulates 11beta-hydroxysteroid dehydrogenase type 1-dependent metabolism of 7-keto- and 7beta-hydroxy-neurosteroids. Nashev, L.G., Chandsawangbhuwana, C., Balazs, Z., Atanasov, A.G., Dick, B., Frey, F.J., Baker, M.E., Odermatt, A. PLoS. One. (2007) [Pubmed]
  7. Transcriptional regulation of human oxysterol 7 alpha-hydroxylase gene (CYP7B1) by Sp1. Wu, Z., Chiang, J.Y. Gene (2001) [Pubmed]
  8. Regulation of steroid hydroxylase CYP7B1 by androgens and estrogens in prostate cancer LNCaP cells. Tang, W., Norlin, M. Biochem. Biophys. Res. Commun. (2006) [Pubmed]
  9. Transcriptional regulation of human oxysterol 7alpha-hydroxylase by sterol response element binding protein. Norlin, M., Chiang, J.Y. Biochem. Biophys. Res. Commun. (2004) [Pubmed]
  10. Metabolism of 4 beta -hydroxycholesterol in humans. Bodin, K., Andersson, U., Rystedt, E., Ellis, E., Norlin, M., Pikuleva, I., Eggertsen, G., Björkhem, I., Diczfalusy, U. J. Biol. Chem. (2002) [Pubmed]
  11. Expression of key enzymes in bile acid biosynthesis during development: CYP7B1-mediated activities show tissue-specific differences. Norlin, M. J. Lipid Res. (2002) [Pubmed]
  12. Structure and functions of human oxysterol 7alpha-hydroxylase cDNAs and gene CYP7B1. Wu, Z., Martin, K.O., Javitt, N.B., Chiang, J.Y. J. Lipid Res. (1999) [Pubmed]
  13. Estrogen-mediated regulation of CYP7B1: a possible role for controlling DHEA levels in human tissues. Tang, W., Eggertsen, G., Chiang, J.Y., Norlin, M. J. Steroid Biochem. Mol. Biol. (2006) [Pubmed]
  14. Inter-conversion of 7alpha- and 7beta-hydroxy-dehydroepiandrosterone by the human 11beta-hydroxysteroid dehydrogenase type 1. Muller, C., Pompon, D., Urban, P., Morfin, R. J. Steroid Biochem. Mol. Biol. (2006) [Pubmed]
  15. Feedback regulation of bile acid synthesis in human liver: importance of HNF-4alpha for regulation of CYP7A1. Abrahamsson, A., Gustafsson, U., Ellis, E., Nilsson, L.M., Sahlin, S., Björkhem, I., Einarsson, C. Biochem. Biophys. Res. Commun. (2005) [Pubmed]
  16. Expression cloning of an oxysterol 7alpha-hydroxylase selective for 24-hydroxycholesterol. Li-Hawkins, J., Lund, E.G., Bronson, A.D., Russell, D.W. J. Biol. Chem. (2000) [Pubmed]
  17. Characterization of the dehydroepiandrosterone (DHEA) metabolism via oxysterol 7alpha-hydroxylase and 17-ketosteroid reductase activity in the human brain. Steckelbroeck, S., Watzka, M., Lütjohann, D., Makiola, P., Nassen, A., Hans, V.H., Clusmann, H., Reissinger, A., Ludwig, M., Siekmann, L., Klingmüller, D. J. Neurochem. (2002) [Pubmed]
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