Regular Article
cDNA Cloning, Heterologous Expression, and Characterization of Mouse CYP2G1, an Olfactory-Specific Steroid Hydroxylase

https://doi.org/10.1006/abbi.1997.9899Get rights and content

Abstract

CYP2G1 is expressed specifically in the olfactory mucosa in rabbits and rats. In the present study, a full-length cDNA for mouse CYP2G1 was obtained using a PCR approach with RNA preparations from the olfactory mucosa of C57BL/6 mice. Sequence comparisons indicated that mouse CYP2G1 is highly homologous in deduced amino acid sequence to rabbit (82.4% identity) and rat CYP2G1 (94.9% identity). RNA blot and immunoblot analyses indicated that mouse CYP2G1 is expressed only in the olfactory mucosa. The coding region of the mouse CYP2G1 cDNA was cloned into a baculoviral expression vector for heterologous production of the enzyme in cultured insect cells. Heterologously expressed mouse CYP2G1 was active in a reconstituted system toward testosterone and progesterone, producing all the major metabolites detected in olfactory microsomal reactions, including 15α-, 15β-, and 2β-hydroxytestosterone from testosterone and two unidentified metabolites from progesterone. Kinetic analysis indicated that mouse CYP2G1 has relatively high affinities toward the steroid substrates, withKmvalues in the micromolar range for both testosterone and progesterone. At a substrate concentration of 10 μm, microsomes of olfactory mucosa had much higher turnover numbers toward testosterone and progesterone than hepatic microsomes, consistent with the olfactory-specific expression of a high-affinity sex steroid hydroxylase. These findings will facilitate further molecular genetics studies on the biological function of CYP2G1 in a mouse model.

References (28)

  • H.-M. Peng et al.

    J. Biol. Chem.

    (1993)
  • P. Nef et al.

    J. Biol. Chem.

    (1989)
  • X. Ding et al.

    Arch. Biochem. Biophys.

    (1991)
  • X. Ding et al.

    Arch. Biochem. Biophys.

    (1994)
  • F.J. Gonzalez et al.

    Methods Enzymol.

    (1991)
  • O.H. Lowry et al.

    J. Biol. Chem.

    (1951)
  • T. Omura et al.

    J. Biol. Chem.

    (1964)
  • P. Nef et al.

    J. Biol. Chem.

    (1990)
  • J. Sheng et al.

    Biochem. Biophys. Res. Commun.

    (1996)
  • D.R. Nelson et al.

    Pharmacogenetics

    (1996)
  • A.R. Dahl et al.

    Science

    (1982)
  • A.R. Dahl et al.

    CRC Crit. Rev. Toxicol.

    (1991)
  • X. Ding et al.

    Handbook Exp. Pharmacol.

    (1992)
  • Cited by (32)

    • Hepatic transcriptional profile and tissue distribution of cytochrome P450 1-3 genes in the red-crowned crane Grus japonensis

      2020, Comparative Biochemistry and Physiology Part - C: Toxicology and Pharmacology
      Citation Excerpt :

      CYP2G19 is an avian specific gene for which the function is still unclear. Mouse Cyp2G1 was found to be uniquely expressed in the olfactory mucosa and to metabolize steroids, acetaminophen, and 2,6-dichlorobenzonitrile (Hua et al., 1997; Gu et al., 1998; Ling et al., 2004). In red-crowned crane, CYP2G19 was mainly expressed in the liver at a moderate level.

    • Mechanisms of olfactory toxicity of the herbicide 2,6-dichlorobenzonitrile: Essential roles of CYP2A5 and target-tissue metabolic activation

      2010, Toxicology and Applied Pharmacology
      Citation Excerpt :

      Among the major nasal P450 enzymes, CYP1A2 and CYP2E1 have been suggested to be nonessential in the metabolic activation and toxicity of DCBN (Eriksson and Brittebo, 1995; Gu et al., 1998). A potentially significant role by CYP2G1, which is uniquely expressed in the OM (Hua et al., 1997), and was ~ 30% less efficient than CYP2A5 was in converting DCBN to GS-DCBN in vitro (Gu et al., 1998), has also been ruled out by our finding that a Cyp2g1-null mouse (Zhou et al., unpublished) was not protected from DCBN-induced nasal toxicity (data not shown). Results from these previous studies are consistent with the present finding that CYP2A5 plays a significant role in DCBN metabolism and toxicity in the OM.

    • Regulation of cytochrome P450 gene expression in the olfactory mucosa

      2004, Chemico-Biological Interactions
      Citation Excerpt :

      CYP2G1, CYP2A3, and CYP2A13 are examples of CYPs in the second group, which are predominantly or exclusively expressed in the OM. The expression of these genes appears to be more stringently regulated, especially for CYP2G1, which is expressed exclusively in the OM [4,61,62]. It is likely that tissue-enriched transcription factors play an important role in the transcriptional regulation of these genes.

    View all citing articles on Scopus

    This investigation was supported in part by NIH Grant DC02640.

    2

    Current address: Department of Biochemistry, Nanjing University, Nanjing, P.R. China.

    3

    To whom correspondence should be addressed at Wadsworth Center, New York State Department of Health, Empire State Plaza, Box 509, Albany, NY 12201-0509. Fax: 518-486-1505. E-mail: xinxin. [email protected].

    View full text