Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this paper we report the analysis of porcine ovarian granulosa cells for the expression of several known hepatic estrogen hydroxylase RNAs. Of the P450s examined, only CYP 1A1 RNA was detected. Accordingly, the regulation of this mRNA was studied. The RNA for CYP 1A1 was dramatically and completely induced within 2 hours after exposure of immortalized granulosa cells to 3-methyl-cholanthrene (3MC) and expression could be inhibited with 10 microM phorbol myristate acetate. This message was also inducible by 3MC in cultured primary granulosa cells isolated from immature and developing follicles. Dexamethasone increased the relative expression of CYP 1A1 RNA in 3MC treated cells. In the absence of 3MC, the CYP 1A1 message was expressed in cultured granulosa cells from developing but not immature follicles, indicating developmental regulation of this enzyme. Further support for developmental regulation was provided by studies which detected the appearance of CYP 1A1 RNA during growth of ovarian follicles in vivo. This is the first report identifying a specific P450 estrogen hydroxylase RNA in ovarian granulosa cells.
J Steroid Biochem Mol Biol 1995 Apr
PMID:Expression of cytochrome P450 1A1, an estrogen hydroxylase, in ovarian granulosa cells is developmentally regulated. 773 3

Trimethadione(TMO) is regarded as a model drug for estimating the hepatic drug oxidative capacity in vivo. However, the P450 isozymes that are responsible for TMO N-demethylation have not been identified clearly yet. This study was designed to determine these P450 isozymes that participate in the TMO N-demethylation in vivo by employing several typical P450 inhibitors and substrates. Male Sprague-Dawley(SD) rats were pretreated with P450 inhibitors or substrates before TMO(100mg/kg, p.o.) treatment. Serum dimethadione(DMO)/TMO ratios were employed for the assessment of metabolic capacity toward TMO. Pretreatment with imidazole and acetone significantly decreased the DMO/TMO ratios in a dose related manner. Weaker inhibitory effects were observed with SKF525A. However, pretreatment with alpha-naphthoflavone, quinine, debrisoquine, triacetyloleandomycin and lauric acid did not affect the ratios. These results suggest that various forms of P450 are involved in TMO metabolism to some extent and that CYP2E1 is attributed to major P450 isozyme for TMO N-demethylation in vivo.
Res Commun Mol Pathol Pharmacol 1995 Feb
PMID:The effects of inhibitors and substrates of different types of cytochrome P450 isozymes on serum dimethadione/trimethadione ratio in rats in vivo. 774 52

The purpose of this study was to investigate the expression and distribution of pulmonary CYP2E1 in mice. The CYP2E1 protein and mRNA were identified by immunoblotting and northern blotting, respectively, while the distribution of the CYP2E1 protein and mRNA was examined by immunohistochemistry and in situ hybridization, respectively. Protein immunoblotting revealed a single band of approximately M(r) 51,000 in lung microsomes of CD-1 male mice. Northern blotting with a 32P-labeled RNA probe for CYP2E1 detected a single species of approximately 2 kb that was similar in size to that of liver CYP2E1. Immunohistochemical studies with the avidin-biotin complex procedure showed that CYP2E1 was localized prominently in the nonciliated Clara cells but was not detected in the ciliated cells of the bronchiolar epithelium. In the lung parenchyma, immunoreactivity for CYP2E1 was evident at minimal levels in alveolar type II cells. In situ hybridization experiments with a 33P-labeled RNA probe showed that the CYP2E1 mRNA was also predominantly localized in the bronchiolar epithelium and was most prominent in the Clara cells. As was found for the CYP2E1 protein, the CYP2E1 mRNA was minimal in cells of the lung parenchyma. These results demonstrated that the CYP2E1 enzyme is preferentially expressed in Clara cells of murine lung. The concentration of CYP2E1 mainly in this cell population may be an important determinant underlying its susceptibility to cytotoxicities induced by xenobiotics bioactivated by this P450 isozyme.
Am J Respir Cell Mol Biol 1995 Jun
PMID:CYP2E1 is preferentially expressed in Clara cells of murine lung: localization by in situ hybridization and immunohistochemical methods. 776 23

The biosynthesis of estrogens is catalyzed by aromatase P450 (P450arom), the product of the CYP19 gene. The tissue-specific expression of the CYP19 gene is regulated by means of tissue-specific promoters through the use of alternative splicing mechanisms. Thus, transcripts containing various 5'-untranslated termini are present in human placenta and other fetal tissues, ovary, brain, and adipose stromal cells. Sequence corresponding to untranslated exon 1.4 is present in 5'-termini of transcripts expressed in adipose tissue and fetal liver, as well as adipose stromal cells in primary culture in the presence of dexamethasone and fetal calf serum (FCS). Identification of hormone-responsive, tissue-specific promoter regions, as well as growth factor-response elements upstream of exon 1.4, may provide insight into the regulation of estrogen biosynthesis in adipose tissue, which is implicated in the development of breast and endometrial cancer. The goals of the present study were to define the 1.4 promoter region with respect to the start of transcription and to characterize the region(s) responsible for conferring glucocorticoid responsiveness on aromatase expression. The transcription initiation site was identified by means of primer extension and S1 nuclease protection analyses. No TATA-like sequence was evident upstream of this site. Various deletion mutations of the upstream flanking region of exon 1.4 and including part of exon 1.4 were made using polymerase chain reaction or restriction enzyme digestion. The genomic fragments were fused upstream of the chloramphenicol acetyltransferase (CAT) reporter gene. These constructs were transfected into adipose stromal cells and fetal hepatocytes in primary culture in medium containing FCS with or without dexamethasone. The -560/+10 base pair (bp) construct expressed CAT activity after a putative silencer element was deleted, and expression was induced by dexamethasone about 3-fold. Transfection of the -330/+170 bp construct, which contains an upstream glucocorticoid response element (GRE) as well as an Sp1-like sequence in untranslated exon 1.4, resulted in an 8-fold stimulation of expression of CAT activity by dexamethasone. The upstream GRE as well as the Sp1-like sequence in untranslated exon 1.4 were mutated separately, and together, to further confirm whether the GRE or Sp1 binding site play a role in the regulation of promoter 1.4-driven transcription. Mutation of either the GRE or Sp1 binding site, or both, in the -330/+170 bp construct, resulted in loss of dexamethasone-induced CAT reporter gene expression.(ABSTRACT TRUNCATED AT 400 WORDS)
Mol Endocrinol 1995 Mar
PMID:Characterization of the sequences of the human CYP19 (aromatase) gene that mediate regulation by glucocorticoids in adipose stromal cells and fetal hepatocytes. 777 80

The effects of PCBs (mixture of 2, 3, 4, 5-tetra; 2, 2', 4, 5, 5'-penta; 2, 2', 3, 3', 6, 6'-hexa and 2, 2', 3, 3', 4, 4', 5, 5'-octa congeners) on androgen production were investigated by suspension of Leydig cells from adult rat testis. hCG-stimulated androgen production was significantly inhibited by PCBs while progesterone level was not affected. Progesterone supported testosterone production was also decreased by PCBs, while conversion of androstenedione to testosterone was unchanged. These results suggest that the activity of microsomal enzyme C21 side-chain cleavage P450 was decreased by PCB treatment of Leydig cells in vitro.
J Steroid Biochem Mol Biol 1995 Jun
PMID:Effect of PCBs on androgen production by suspension of adult rat Leydig cells in vitro. 777 64

Steroid hormones are an important class of hormones synthesized from cholesterol by a number of endocrine organs; including ovaries, placenta, testes and adrenal glands. The first and rate-limiting step in steroidogenesis is the cleavage of the side-chain of the cholesterol molecule, catalysed by a cytochrome P450 enzyme, cholesterol side-chain cleavage enzyme. This enzyme, as with other P450 enzymes, produces oxygen radicals. Oxygen free radicals can cause deleterious effects such as cross-linking and aggregation of proteins. Cells can protect against such damage with the use of antioxidants. The corpus luteum, or 'yellow body', of the ovary is very steroidogenic and is exceedingly rich in the yellow antioxidant, beta-carotene. The corpus luteum produces the steroid hormone progesterone that is needed to support pregnancy. Here we have shown that by depleting, or conversely repleting, luteal cells of their beta-carotene content in vitro that P450 side-chain cleavage enzyme became covalently non-disulfide cross-linked to its electron donor, adrenodoxin, and hence inactivated. Bovine luteal cells were cultured in 10% fetal calf serum with or without additional treatments for up to 72 h. Under control conditions the cellular levels of beta-carotene and alpha-tocopherol fell by 50% within 24 h and remained low. P450 side-chain cleavage enzyme become non-disulfide covalently cross-linked to its electron donor, adrenodoxin, as determined by Western immunoblotting (N = 18). Aminoglutethamide inhibited this cross-linking. The addition of beta-carotene at levels found in bovine serum, but not alpha-tocopherol or ascorbic acid, inhibited the degree of the cross-linking.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Endocrinol 1995 Mar
PMID:The antioxidant beta-carotene prevents covalent cross-linking between cholesterol side-chain cleavage cytochrome P450 and its electron donor, adrenodoxin, in bovine luteal cells. 778 11

In granulosa cells, growth factor IGF I plays a major role in both growth and differentiation, acting through an autocrine/paracrine mechanism, and its production is regulated by FSH, via cyclic AMP (cAMP). As protein kinase C is also involved in granulosa cell function, we investigated the possibility that its activation could balance the positive effects of FSH. Using pig granulosa cells cultured in vitro, we studied the effects of protein kinase C activation by tetradecanoylphorbol acetate (TPA) on IGF I mRNA level. We also checked morphological modifications, cAMP production and steroidogenesis at the P450 side chain cleavage mRNA and progesterone levels. Our data demonstrate that protein kinase C activation antagonizes the in vitro FSH-induced differentiation, particularly morphological modifications and accumulation of IGF I mRNA. These inhibitory effects on FSH responses suggest that there could be a balance between protein kinase A and protein kinase C pathways in regulating differentiation in pig granulosa cells.
Mol Cell Endocrinol 1995 Jan
PMID:Protein kinase C inhibition of in vitro FSH-induced differentiation in pig granulosa cells. 779 38

Cytochrome P450 (P450) 2B5 was recently found to be functionally distinct from three other rabbit P450 2B forms, based on androstenedione hydroxylase activities. In this investigation, we examined the frequency of the P450 2B5-null phenotype and the functional consequences of polymorphic P450 2B5 expression in hepatic microsomes from phenobarbital-treated rabbits. Four of the 10 animals examined did not have detectable levels of P450 2B5 mRNA and exhibited much lower microsomal androstenedione 15 alpha- and 16 alpha-hydroxylase activities. The 15 alpha-hydroxylase activity was found to correlate (r = 0.91) with liver P450 2B5 mRNA. P450 2B4 and 2B5 were stably expressed in human kidney 293 cells to further characterize substrate specificities and to investigate mechanism-based inactivation by phencyclidine. P450 2B4 was 4-16-fold more active than 2B5 towards benzphetamine, 7-ethoxycoumarin, methylenedioxybenzene, and pentoxyresorufin. Benzyloxyresorufin O-debenzylase activity was 160-fold higher for P450 2B4 than P450 2B5. Anti-P450 2B4 IgG inhibited benzyloxyresorufin O-debenzylation nearly completely in untreated and phenobarbital-induced liver microsomes. Phencyclidine selectively inactivated P450 2B4, compared with 2B5, in both human kidney 293 cell and liver microsomes. Poor inactivation of P450 2B5 by phencyclidine was found to be a result of its low maximal rate constant. Results of this study establish the idea that the metabolic consequences of phenobarbital induction depend on the potential of animals to express functionally variant P450 2B forms. Furthermore, we conclude that one or more of the 11 amino acid differences between these highly related P450 forms are critical to their substrate specificities and selective inactivation.
Mol Pharmacol 1994 Dec
PMID:Catalytic selectivity and mechanism-based inactivation of stably expressed and hepatic cytochromes P450 2B4 and 2B5: implications of the cytochrome P450 2B5 polymorphism. 780 29

The tertiary structure of cytochrome P450 14 alpha demethylase--Candida albicans (P450 CA) is modeled on the basis of sequence alignment with two closely related proteins and the crystallographic structure of Pseudomonas putida P450cam. The secondary structure prediction system used combines the information from several algorithms and trains the data to offer an optimized prediction of the known P450cam. The trained algorithm was then used to predict the secondary structure of the other P450 sequences. The prediction of the surface coil regions was aided by an alignment between P450 CA and the homologous sequences P450 14 alpha demethylase--Saccharomyces cerevisiae (66 SD) and P450 14 alpha demethylase--Candida tropicalis (72 SD). The prediction and alignment information was combined to establish an alignment between P450 CA and P450cam, and to assign full secondary structure to the target protein. This secondary structure was folded from the template of P450cam and the predicted structure was relaxed by molecular dynamics. Model checking highlighted minor adjustments in the alignment, correctly orienting hydrophobic and hydrophilic side chains. The model offers explanations for several known experimental results and suggests further investigations that may prove fruitful in understanding the structure and mechanisms of the P450 family (Porter, T.D. and Coon, M.J. Minireview cytochrome P450. J. Biol. Chem. 1991, 266, 13469-13472. Waterman, M.R. Cytochrome P450 cellular distribution and structural considerations. Current Opinion in Structural Biology 1992, 2, 384-387. Aoyama, Y., Yoshida, Y., Sonohdo, Y. and Sato, Y. Structural analysis of the interaction between the side-chain of substrates and the active site of lanosterol 14 alpha demethylase (P450 14DM) of yeast. Biochim. Biophys. Acta 1992, 1122, 251-255.).
J Mol Graph 1994 Sep
PMID:Modeling cytochrome P450 14 alpha demethylase (Candida albicans) from P450cam. 781 60

Maize seedlings, like seedlings of many other plants, are rich in cytochrome P450 (P450) enzyme activity. Four P450 genes (CYPzm1-4), isolated from a seedling-specific cDNA library, are characterized by a transient and seedling-specific expression pattern. The maximum steady state mRNA levels are reached at 3 days in root and at 7 days in shoot tissue, respectively. All four genes belong to one gene family and are closely related to the CYP71 family of plant P450 genes, which includes the enzymes of the ripening avocado fruit (CYP71A1) and eggplant hypocotyls (CYP71A2, A3, A4). The expression of these related P450 genes in monocot and dicot plants indicates that these enzymes play a significant role in plants; however, the in vivo enzyme functions are unknown. The divergence of the four members of the maize gene family is sufficiently high to account for different substrate and/or reaction specificity. Although the general expression pattern of the four genes is identical, the maximum steady-state mRNA levels vary in different maize lines. In situ hybridisation reveals the highest mRNA levels in the coleoptile, the first developed leaflets, the ground tissue of the nodular complex, and in the cortex and pith of the region of cell division in the root. The mapping of the maize CYPzm genes shows that, as in animals, P450 genes of the same family can be clustered. The presence of the CYPzm gene cluster in maize argues for generation of distinct plant P450 gene families by gene duplication.
Mol Gen Genet 1995 Jan 06
PMID:Expression of a cytochrome P450 gene family in maize. 782 5


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