A major glucocorticoid-inducible P450 in rat liver is not P450 3A1

J Biochem. 1994 Jul;116(1):114-20. doi: 10.1093/oxfordjournals.jbchem.a124482.

Abstract

A new P450 3A cDNA (RL33) has been cloned from a liver cDNA library of untreated male rat. RL33 is 2032 nucleotides in length and has an open reading frame of 502 amino acid residues. The nucleotide sequence of its 5'-noncoding region is completely identical with that of a genomic clone of P450 3A1 isolated by Burger et al. [Proc. Natl. Acad. Sci. USA 89, 2145-2149 (1992)]. Compared with rat P450 3A1, P450 RL33 showed 98 and 97% identities in the nucleotide and deduced amino acid sequences, respectively, with the deletion of 2 amino acids and substitution of 12 amino acids. These residues were localized around amino acids 107-230. Recently Kirita and Matsubara have isolated the same P450 3A cDNA (cDEX) from dexamethasone (DEX)-treated rat liver [Arch. Biochem. Biophys. 307, 253-258 (1993)]. Northern blot analysis using an oligonucleotide probe specific for P450 RL33/cDEX revealed that P450 RL33/cDEX mRNA was induced strongly by pregnenolone 16 alpha-carbonitrile and DEX and weakly by phenobarbital (PB) and triacetyloleandomycin. We constructed a P450 3A cDNA library by the reverse transcriptase-polymerase chain reaction using common primers to P450 RL33/cDEX, 3A1, and 3A2, and subcloned the cDNAs into pUC119. The expression level of P450 RL33/cDEX mRNA was investigated by identifying each clone with the above oligonucleotide probe. P450 RL33/cDEX mRNA represented over 70% of the total P450 3A mRNA from untreated, PB-, and DEX-treated rat liver. These results indicated that the major DEX-inducible form of P450 3A is P450 RL33/cDEX and not P450 3A1.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cloning, Molecular
  • Cytochrome P-450 Enzyme System / biosynthesis
  • Cytochrome P-450 Enzyme System / genetics*
  • Dexamethasone / pharmacology*
  • Enzyme Induction
  • Isoenzymes / biosynthesis
  • Isoenzymes / genetics*
  • Liver / drug effects*
  • Liver / enzymology
  • Male
  • Molecular Sequence Data
  • Polymerase Chain Reaction / methods
  • RNA-Directed DNA Polymerase
  • Rats
  • Rats, Sprague-Dawley

Substances

  • Isoenzymes
  • Dexamethasone
  • Cytochrome P-450 Enzyme System
  • RNA-Directed DNA Polymerase

Associated data

  • GENBANK/D29967