Human Cytochrome P450 Genes Research Articles

Transcriptional regulation of the human aromatase cytochrome P450 gene expression in human placental cells

The human aromatase cytochrome P450 gene, CYP 19, spans more than 75 kb in the human genome. Recently, it is proposed that the expression of the CYP 19 gene is regulated in part by tissue-specific promoters through the use of mechanisms involving alternative splicing of a number of untranslated exons. In this study, we have characterized cis-acting elements involved in the transcriptional regulation of the gene in human placental cells, where the majority of the transcripts contain the 5'-untranslated sequence encoded by exon I.1. By transient expression analyses in human BeWo choriocarcinoma cells using the bacterial chloramphenicol acetyltransferase gene as a reporter gene, we localized an enhancer element in the region between -242 and -166 relative to the major cap site of the gene. Furthermore, we demonstrate that the element between -2141 and -2115 participates in the 12-O-tetradecanoylphorbol 13-acetate (TPA)-mediated enhancement of gene expression. By screening a human placental cDNA expression library, we have isolated a cDNA clone (lambda 1-2) encoding a peptide which binds specifically to the element between -2141 and -2115. Sequence analysis of the clone revealed that the insert of lambda 1-2 encodes a part of the amino acid sequence of NF-IL6 (also termed as LAP and C/EBP beta). Northern blot analysis reveals expression of the NF-IL6 gene in BeWo cells and human placenta. These results indicate that NF-IL6 is one of the nuclear factors which participate in TPA-mediated transcriptional enhancement of CYP 19 gene expression.

Fluorescencein situ hybridization analysis of chromosomal localization of three human cytochrome P450 2C genes (CYP2C8, 2C9, and 2C10) at 10q24.1

Chromosomal localization of three human cytochrome P450 genes belonging to the CYP2C subfamily (CYP2C8, 2C9, and 2C10) was identified by fluorescence in situ hybridization (FISH). An original MP-8 clone was used as a DNA probe for the assignment of the CYP2C10 gene, while two cDNA probes, a 1.37 kb fragment of CYP2C8 and a 1.19 kb fragment of CYP2C9, were obtained after amplifying the predicted fragments (MP-20 and MP-4 clones, respectively) by polymerase chain reaction using a single human liver cDNA library. The results showed that three human CYP2C8, 2C9, and 2C10 cDNAs were located at the same subchromosomal region, 10q24.1.

Expression of xenobiotic-metabolizing cytochrome P450 forms in human adult and fetal liver

Expression of human cytochrome P450 (CYP) genes in human adult and fetal liver were studied using the reverse transcriptase-polymerase chain reaction (RT-PCR) method. In adult liver mRNA of CYPs 1A1, 1A2, 2A6/2A7, 2B6/2B7, 2C8-19, 2D6, 2E1, 3A3/3A4 and 3A7 were detected while CYPs 2F1 and 4B1 were absent. In fetal liver mRNA of CYPs 2C8, 2D6, 3A3/3A4 and 3A7 were found but all other forms studied were undetectable. The results provide a comprehensive qualitative picture of the expression of CYP genes in families CYP1 through CYP4 in human adult and fetal liver.

Correlation between pulmonary cytochrome P450 transcripts and the organ-selective pneumotoxicity of 3-methylindole

3-Methylindole (3MI) is a species- and organ-selective pneumotoxin; goats are the most susceptible species, mice are intermediate in susceptibility, and rabbits are the least susceptible species to its toxicity. Four different cDNA probes representative of human cytochrome P450 genes CYP2F1, CYP4B1, CYP2A6, and CYP2B6 were hybridized against RNA from lung and liver tissues of goat, mouse and rabbit. Transcripts representative of pulmonary P450s CYP2F1, CYP4B1 and CYP2B6 were present in goat lung. Transcripts for the CYP2F1 and CYP4B1 genes were observed in rabbit and mouse lung. In general, the probes selectively hybridized to pulmonary but not hepatic transcripts of all three species. The differences in susceptibilities among the three species could not be explained by the lack of 4B1 and 2F1 transcripts in the lungs of mice or rabbits that are less susceptible than goats, but the selective expression in the lung tissues of all three species may participate in the organ-selective bio-activation and pulmonary toxicity of 3MI in these species.

Structure and expression of human cytochrome P-450 genes

Conference Article| February 01 1989 Structure and expression of human cytochrome P-450 genes CHRISTOPHER J. GRIFFITH; CHRISTOPHER J. GRIFFITH *Department of Biochemistry, University College London, Gower Street, London WC1E 6BT, U.K. Search for other works by this author on: This Site PubMed Google Scholar COLIN N. A. PALMER; COLIN N. A. PALMER †Department of Biochemistry, St. Bartholomew's Hospital Medical College, University of London, Charterhouse Square, London EC1M 6BQ, U.K. Search for other works by this author on: This Site PubMed Google Scholar INES SANTISTEBAN; INES SANTISTEBAN †Department of Biochemistry, St. Bartholomew's Hospital Medical College, University of London, Charterhouse Square, London EC1M 6BQ, U.K. Search for other works by this author on: This Site PubMed Google Scholar ARABELLA HUTTER; ARABELLA HUTTER †Department of Biochemistry, St. Bartholomew's Hospital Medical College, University of London, Charterhouse Square, London EC1M 6BQ, U.K. Search for other works by this author on: This Site PubMed Google Scholar ELIZABETH A. SHEPHARD; ELIZABETH A. SHEPHARD *Department of Biochemistry, University College London, Gower Street, London WC1E 6BT, U.K. Search for other works by this author on: This Site PubMed Google Scholar IAN R. PHILLIPS IAN R. PHILLIPS †Department of Biochemistry, St. Bartholomew's Hospital Medical College, University of London, Charterhouse Square, London EC1M 6BQ, U.K. Search for other works by this author on: This Site PubMed Google Scholar Biochem Soc Trans (1989) 17 (1): 192–193. https://doi.org/10.1042/bst0170192 Article history Received: June 20 1988 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation CHRISTOPHER J. GRIFFITH, COLIN N. A. PALMER, INES SANTISTEBAN, ARABELLA HUTTER, ELIZABETH A. SHEPHARD, IAN R. PHILLIPS; Structure and expression of human cytochrome P-450 genes. Biochem Soc Trans 1 February 1989; 17 (1): 192–193. doi: https://doi.org/10.1042/bst0170192 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Society Transactions Search Advanced Search This content is only available as a PDF. © 1989 Biochemical Society1989 Article PDF first page preview Close Modal You do not currently have access to this content.

Transfection of a human cytochrome P-450 gene into the human lymphoblastoid cell line, AHH-1, and use of the recombinant cell line in gene mutation assays

We have demonstrated that the human cytochrome P1-450 gene can be transfected into the AHH-1 human lymphoblastoid cell line using the pHEBo vector and hygromycin selection. The transfected gene was expressed when regulatory sequences derived from the herpes simplex virus thymidine kinase gene were incorporated in appropriate orientations. Gene expression was monitored at the enzyme level using assays for 7-ethoxyresorufin deethylase, 7-ethoxycoumarin deethylase and benzo[a]pyrene hydroxylase activities. Bulk transformed cell populations had 2- to 3-fold more of these enzyme activities compared with control populations. Subclones of the bulk population expressing still higher levels of 7-ethoxyresorufin deethylase activity were also obtained. Expression of the transfected cytochrome P1-450 gene was stable for 20-30 days in the presence of hygromycin B. The transformed cell populations were found to be suitable for use in gene locus mutation assays and the mutagenicity of aflatoxin-B1 and 2-acetylaminofluorene (AAF) were examined. Aflatoxin-B1 was found to be 2-3 times more mutagenic to cells bearing the transfected cytochrome P1-450 activity as compared with control cells. In contrast, no difference in AAF mutagenicity was observed. Analysis of the AAF metabolite profile indicated that cells expressing the transfected cytochrome P1-450 gene produced 8-fold more N- and 7-hydroxy-AAF than control cells. The similarity in mutagenic responses between control cells and cells bearing the transfected cytochrome P1-450 gene may be due to the low deacetylase activity of AHH-1 cells. These observations indicate that this vector and expression system are suitable for introducing novel metabolic activities into the AHH-1 cell line.

Structure and expression of human cytochrome P-450 genes

Structure and expression of human cytochrome <i>P</i>-450 genes

Identification and quantification of a messenger ribonucleic acid induced by polynuclear aromatic hydrocarbons--using a cloned human cytochrome P-450 gene.

We have isolated four overlapping human genomic clones associated with the polynuclear aromatic hydrocarbon-induced form of cytochrome P-450. The form of P-450 most closely associated with polynuclear aromatic hydrocarbons induction has been defined as P1-450. These four overlapping genomic clones span a total of 31.0 X 10(3) base pairs in length with the coding sequence lying in the center of these clones. Translation in vitro of 3-methylcholanthrene-induced mRNA, selected with the human P1-450 genomic clone, detect a protein with Mr 52000, which is immunoprecipitable by the anti-(mouse P1-450) antibody. The isolated human P1-450 genomic clone hybridizes to 3-methylcholanthrene-induced mRNA from monkey liver, benzanthracene and 3-methylcholanthrene-treated human mammary tumor cells (MCF-7), but not to isosafrole-treated human cells. Upon treatment with polynuclear aromatic hydrocarbons there is a positive correlation between induced arylhydrocarbon hydroxylase (flavoprotein-linked monoxygenase) activity and the amount of mRNA that hybridizes to the isolated human genomic clone for P1-450. The size of mRNA, induced from human cells and monkey liver by polynuclear aromatic hydrocarbons, is around 3.3 X 10(3) base pairs, which is the same as the larger of two mRNA induced by polynuclear aromatic hydrocarbons in the inbred strain of mouse (C57BL/6N). Our data also showed that the isolated DNA clone can detect a mRNA size of 3.3 X 10(3) base pairs from phytohemagglutinin-activated, benzanthracene-treated human lymphocytes. Densitometer scanning indicated the presence of a 3.6-fold variation (highest-lowest) in the levels of lymphocyte P1-450 mRNA contents among six individuals studied.