Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.7.48 (transcriptase)
9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Congenital adrenal hyperplasia (CAH) comprises a family of inherited human disorders caused by a defect in cortisol biosynthesis. We previously reported absent cholesterol side-chain cleavage enzyme cytochrome P450 (P450scc) expression in rabbits affected with CAH. Further molecular studies via Southern blotting analyses, using a full-length human P450scc cDNA probe and a cloned rabbit P450scc cDNA probe, demonstrated the absence of P450scc DNA fragments in CAH animals. Reverse transcriptase-based polymerase chain reactions revealed that P450scc mRNA was not detectable in the adrenals of CAH rabbits, confirming the previous findings of absent P450scc gene expression by Northern and Western blotting. Cloning and sequencing of a 1336-basepair fragment of rabbit P450scc cDNA (85% of the coding sequence) revealed an approximately 80% identical nucleotide sequence and a 76% identical amino acid sequence compared to the human P450scc cDNA. We conclude that a large deletion mutation in the P450scc gene is most likely responsible for the absent P450scc gene expression resulting in the lethal and feminizing form of CAH in the rabbit. Further investigation of adrenal and gonadal steroidogenic enzyme gene expression in this CAH animal model will provide a greater understanding of the molecular genetics of CAH, while wild-type P450scc gene transfer experiments using CAH adrenals in vitro or in vivo will ultimately characterize the molecular basis of CAH and provide a foundation for CAH gene therapy modality.
...
PMID:Inherited congenital adrenal hyperplasia in the rabbit is caused by a deletion in the gene encoding cytochrome P450 cholesterol side-chain cleavage enzyme. 768 38

The aim of the study was to investigate whether the adrenal renin-angiotensin system plays an independent role in the regulation of mineralocorticoid biosynthesis in the adrenal gland and to explore the mechanisms of this action. Twelve-week-old male Sprague-Dawley rats were studied: 22 rats were maintained on a regular diet; 27 and 22 rats received a low salt diet with and without treatment, respectively, with the angiotensin II (Ang II) AT1-subtype receptor antagonist losartan (10 mg/kg per day). A fraction of each group of rats underwent bilateral nephrectomy (n = 12, 15, and 10, respectively) and was killed 48 hours later. In an additional group of 24 (12 intact and 12 nephrectomized) rats, the effects of the Ang II AT2-subtype receptor antagonist PD123319 were investigated. In intact rats, plasma renin activity (PRA) and adrenal renin activity and expression were progressively raised by salt restriction and losartan, whereas aldosterone synthase mRNA and plasma aldosterone (PA) levels were increased by salt restriction and reduced by losartan. Forty-eight hours after nephrectomy, PRA fell to undetectable levels; in contrast, adrenal renin expression, assessed by semiquantitative reverse-transcriptase polymerase chain reaction (using GAPDH as a standard for gene expression), showed an 18-fold increase and was further increased after salt restriction and losartan (all P < .05). Also, adrenal renin activity was raised after nephrectomy and further increased after salt restriction (P < .05) and losartan. Cytochrome P450 aldosterone synthase expression in the adrenal cortex was stimulated by nephrectomy alone and by nephrectomy combined with low salt intake (P < .05), with consequent increases in PA concentrations. In losartan-treated salt-restricted nephrectomized rats, cytochrome P450 aldosterone synthase expression (P < .05 versus nephrectomy alone and nephrectomy plus salt restriction) and PA concentrations were diminished (P < .05) in spite of the observed increases of adrenal renin expression. The AT2-receptor antagonism did not significantly affect PRA, adrenal renin, and aldosterone biosynthesis and production in either intact or nephrectomized salt-restricted rats. These results demonstrate that the adrenal renin-angiotensin system plays an independent role in the regulation of mineralocorticoid biosynthesis in vivo. This action is mediated primarily via the Ang II AT1-subtype receptors.
...
PMID:Role of tissue renin in the regulation of aldosterone biosynthesis in the adrenal cortex of nephrectomized rats. 935 60

S-Warfarin 7-hydroxylation, S-flurbiprofen 4'-hydroxylation, and diclofenac 4'-hydroxylation activities were determined in liver microsomes of 30 humans of which 19 were wild-type (Arg144.Ile359), 8 were heterozygous Cys (Cys144.Ile359), and 3 were heterozygous Leu (Arg144.Leu359) allelic variants of the cytochrome P450 2C9 (CYP2C9) gene. All of the human samples examined contained P450 protein(s) immunoreactive with anti-CYP2C9 antibodies in liver microsomes. Individuals with the Cys144 allele of CYP2C9 had similar, but slightly lower, activities for the oxidations of these substrates than those of wild-type CYP2C9. One of the three human samples heterozygous for the Leu359 allele had very low Vmax and high Km values for the oxidation of three substrates examined, while the other two individuals gave kinetic parameters comparable to those seen in the wild-type and Cys144 CYP2C9. Reverse transcriptase-polymerase chain reaction analysis, however, showed that all of the three human samples with the heterozygous Leu359 variant were found to express both Ile359 and Leu359 variants at relatively similar extents in liver RNA of three humans. These results suggest that the Cys144 variant of CYP2C9 catalyzes the CYP2C9 substrates at rates comparative to, but slightly lower than, those of wild-type CYP2C9, while the Leu359-allelic variant has slower rates for the oxidation of these drug substrates. Activities for the oxidation of these CYP2C9 substrates in humans with heterozygous Leu359 allele is likely to be dependent on the levels of expression of each of the wild- and Leu-variants in the livers. However, one of the humans with a heterozygous Leu allele was found to have very low activities towards the oxidation of CYP2C9 substrates. The basis of this defect in catalytic functions towards CYP2C9 substrates is unknown.
...
PMID:Comparative studies on the catalytic roles of cytochrome P450 2C9 and its Cys- and Leu-variants in the oxidation of warfarin, flurbiprofen, and diclofenac by human liver microsomes. 969 79

Five murine cytochrome P450 (CYP) 2C cDNAs were cloned and characterized, including four new members of this subfamily: CYP2C37, CYP2C38, CYP2C39, and CYP2C40. The cDNAs ranged from 1716 to 1812 bp in length and encoded polypeptides of 490 amino acid residues except for CYP2C40, which contained an additional glutamic acid residue at the carboxyl terminus. The amino acid identity of the murine CYP2Cs ranged from 69 to 92%, while the overall amino acid identity was 60%; however, within the six putative substrate recognition sites the identity was only 25 to 41%, suggesting possible differences in substrate specificity and product profiles. The CYP2C cDNAs were expressed in Escherichia coli following modification of the N-terminus. All five recombinant CYP2Cs metabolized arachidonic acid, but with different metabolic profiles and catalytic rates. Based on coelution with authentic standards on reverse-phase HPLC, themajor metabolites were tentatively identified asfollows: CYP2C29 and CYP2C39 produced 14, 15-cis-epoxyeicosatrienoic acid (EET); CYP2C37 produced 12-hydroxyeicosatetraenoic acid (HETE); CYP2C38 produced 11,12-EET; and CYP2C40 produced an unidentified metabolite that coeluted with 16-,17-, and 18-HETEs. The turnover numbers for CYP2C29, CYP2C37, CYP2C38, CYP2C39, and CYP2C40 were 0.34, 1.12, 5.15, 0.51, and 0.15 nmol/nmol/min, respectively. Reverse transcriptase-polymerase chain reaction demonstrated the presence of CYP2C29 mRNA in liver as well as in extrahepatic tissues including brain, kidney, lung, heart, and intestine. CYP2C38 and CYP2C40 were found in liver, brain, kidney, and intestine, with trace amounts in lung and heart, while CYP2C37 and CYP2C39 appeared to be liver specific.
...
PMID:Cloning and expression of murine CYP2Cs and their ability to metabolize arachidonic acid. 972 Nov 82

We have recently reported that beta-ionone induces cytochrome P450 (P450) 2B1 in rats. Effects of beta-ionone on the expression of other P450 isozymes and NADPH-P450 reductase were further investigated in Sprague Dawley rats. Administration of beta-ionone subcutaneously 72 and 48 h before sacrificing the animals not only significantly induced the liver microsomal activities of P450-associated enzymes and NADPH-P450 reductase, but also clearly increased in the level of P450 1A1/2, P450 2C, and NADPH-P450 reductase proteins. The induction of P450 1A1/2 and 2C by beta-ionone was much greater in male than in female as measured by western immunoblotting. Reverse transcriptase-polymerase chain reactions showed that, in addition to P450 2B1 and 2B2 mRNAs, P450 1A2, 2C6 and NADPH-P450 reductase mRNAs were increased when beta-ionone was administered. Our previous and present results indicated that beta-ionone may induce several P450s and NADPH-P450 reductase by the accumulation of their corresponding mRNAs.
...
PMID:Effects of beta-ionone on the expression of cytochrome P450s and NADPH-cytochrome P450 reductase in Sprague Dawley rats. 974 58

Reverse transcriptase-polymerase chain reaction was used to amplify a partial cDNA from rabbit lung mRNA that shared 77% protein sequence identity with the mouse pregnane X receptor (PXR). Rapid amplification of cDNA ends from a rabbit kidney lambdaZAP expression library resulted in the isolation of overlapping cDNAs spanning the complete coding sequence. The deduced amino acid sequence of 411 residues exhibited 79% overall amino acid identity with human PXR and 77% identity with mouse PXR. Based on this protein sequence relationship and a similar degree of conservation exhibited by the mouse and human PXR orthologs, the cDNA appears to encode the rabbit PXR ortholog. 5'-rapid amplification of cDNA ends performed on an adaptor-ligated cDNA library from rabbit liver revealed the presence of an alternate mRNA, which differed at the 5'-terminus. RNase protection assays indicated that the alternate mRNA was expressed at >50-fold lower levels in rabbit kidney and liver. Rifampicin treatment of CV-1 cells cotransfected with a rabbit PXR expression plasmid and a luciferase reporter construct containing two copies of the DR3 enhancer from CYP3A23 produced a 6-fold induction of luciferase activity. In contrast, rat PXR was not responsive to this antibiotic under the same conditions. Pregnenolone 16alpha-carbonitrile was an efficacious activator of rat PXR, but failed to significantly activate rabbit PXR at equivalent concentrations. These results indicate that the ligand activation profile of rabbit PXR is distinct from rat PXR and more closely resembles that of human PXR. The rabbit PXR activation profile is consistent with the cytochrome P450 (P450) 3A6 induction profile in rabbits.
...
PMID:Rabbit pregnane X receptor is activated by rifampicin. 1077 31

A new member of the CYP3A gene family has been cloned from the teleost fish medaka (Oryzias latipes) by reverse-transcriptase polymerase chain reaction (RT-PCR). Degenerate primers homologous to highly conserved regions of known CYP3A sequences were used for initial RT-PCRs. Individual PCR products were cloned, sequenced, and identified as those belonging to the cytochrome P450 superfamily based on amino acid sequence similarity and the presence of the highly conserved heme-binding region. PCR products were subsequently used as probes to screen a complementary DNA library. A full-length cDNA clone was identified containing a 1758-base-pair (bp) insert with an open reading frame encoding a single peptide of 500 amino acids. Comparisons of the deduced amino acid sequence to other known cytochrome P450 sequences indicate that this gene product is most similar to the CYP3A gene family and has been designated as CYP3A38 by the cytochrome P450 nomenclature committee. Northern blot analysis identified two abundant CYP3A related transcripts in liver of both male and female adults and demonstrated quantitative differences in abundance according to gender. Similarly, Western blot analysis demonstrated the presence of two abundant cytochrome P450 related proteins in liver of both male and female adults. These results suggests that O. latipes contains multiple forms of CYP3A. Heterologous expression of CYP3A38 cDNA in HEK 293 cells produced a single protein that was reactive with anti-scup P450A (CYP3A) polyclonal antibody. Microsomes of HEK 293 cells expressing recombinant CYP3A38 protein actively catalyzed the hydroxylation of testosterone.
...
PMID:Identification and characterization of a cDNA encoding cytochrome P450 3A from the fresh water teleost medaka (Oryzias latipes). 1090 Jan 29

DAX-1 and SF-1 are members of the orphan nuclear receptor superfamily that are critical regulatory components of the hypothalamic-pituitary-adrenal-gonadal axis. In adrenal and gonadal tissues they regulate the expression of the cytochrome P450 steroid hydroxylase genes, key mediators of steroidogenesis. The identification of a number of steroid hydroxylases in human skin prompted us to investigate the presence of DAX-1 and SF-1. Immuno histochemical analysis of human skin revealed a distinctive staining pattern for DAX-1 and SF-1 in skin and its appendages. Prominent staining for DAX-1 was confined to the epidermis, sebaceous glands, sweat glands, and outer root sheath of the hair follicle with weaker expression in the inner root sheath, matrix cells, and dermal papilla cells. Similarly, SF-1 was also detected in the epidermis but displayed a scattered nuclear pattern across all layers. SF-1 immunoreactivity was also detected in the exocrine glands and was stronger than DAX-1 in the inner root sheath, matrix cells, and dermal papilla cells. Co-localization of DAX-1 and SF-1 was demonstrated by immunocytochemistry in the HaCaT keratinocyte cell line, primary keratinocytes, preadipocytes, and dermal papilla cells. Reverse transcriptase-polymerase chain reaction analysis demonstrated the expression of DAX-1 and SF-1 mRNA in whole human skin and Western analysis also confirmed the presence of DAX-1 protein in skin-derived cells. Our investigations demonstrate that two important regulators of steroidogeneisis are present in human skin and its appendages. These transcription factors may have a role in cutaneous steroidogenesis and thus be involved in hair follicle cycling or pathologies associated with steroids. Further studies are needed to determine the functional roles of DAX-1 and SF-1 in human skin.
...
PMID:Transcriptional regulators of steroidogenesis, DAX-1 and SF-1, are expressed in human skin. 1188 23

Changes in gene expression regulated by peroxisome proliferator-activated receptor gamma (PPARgamma) and in gene expression related to the inhibin/activin-follistatin system in the rat testis induced by a single oral administration of di-n-butyl phthalate (DBP) (8.6 mmol/kg) were examined and compared with those in the control rats using reverse-transcriptase polymerase chain reaction (RT-PCR). The increase in cytochrome P450 4A1 mRNA, which is regulated by PPARalpha, was significant, but not so profound as the increase of P450 4A1 mRNA in the liver. In contrast, a remarkable increase in the mRNA level of plasminogen activator inhibitor-1 (PAI-1) was found in the testis, suggesting the activation of PPARgamma. The substantial increase in PAI-1 may be related to the disruption of spermatogenesis. On the other hand, significant suppression of the mRNA level of inhibin beta(B) and elevation in the mRNA level of follistatin, an activin-binding protein, were observed after the DBP-administration. Activin B, a homodimer of inhibin beta(B), is known to stimulate spermatogonial proliferation. The present results suggest that the suppression of spermatogenesis resulting from the changes in the expression of genes involved in the inhibin/activin-follistatin system is one of the mechanisms of the testicular atrophy induced by DBP.
...
PMID:Changes in peroxisome proliferator-activated receptor gamma-regulated gene expression and inhibin/activin-follistatin system gene expression in rat testis after an administration of di-n-butyl phthalate. 1256 98

The influence of activation of glutamate receptor (GluR) on outward K(+) current in cultured neonate rat hippocampal astrocytes was investigated. Patch-clamp analysis of K(+) channel currents in cultured astrocytes identified the existence of 71 +/- 6 and 161 +/- 11 pS single-channel K(+) currents that were sensitive to changes in voltage and [Ca(2+)](i) and blocked by external TEA but not by charybdotoxin, iberiotoxin, apamin, or 4-aminopyridine. Reverse transcriptase (RT)-PCR and Northern blot analysis revealed transcripts of the Ca(2+)-activated K(+) channel (K(Ca)) beta(4)-subunit (beta4) (KCNMB4) in cultured astrocytes. Expression of the metabotropic glutamate receptor (mGluR) subtypes mGluR1 and mGluR5 and the ionotropic glutamate receptor (iGluR) subtypes iGluR1 and iGluR4 were detected by RT-PCR and immunofluorescence analysis in cultured astrocytes. The mGluR agonists L-glutamate and quisqualate increased the open state probability (NP(o)) of the 71 and 161 pS K(+) channel currents that were prevented by the mGluR receptor antagonists 1-aminoindan-1,5-dicarboxylic acid or L-(+)-2-amino-3-phosphonopropionic acid and not by the iGluR antagonists (+)-5-methyl-10,11-dihydro-5H-dibenzo [a,d] cyclohepten-5,10-imine maleate or CNQX. Activation of the two types of K(+) channel currents by mGluR agonists was attenuated by pertussis toxin and by inhibition of phospholipase C (PLC) or cytochrome P450 arachidonate epoxygenase. These results indicate that brain astrocytes contain the KCNMB4 transcript and express two novel types of K(Ca) channels that are gated by activation of a G-protein coupled metabotropic glutamate receptor functionally linked to PLC and cytochrome P450 arachidonate epoxygenase activity.
...
PMID:Metabotropic glutamate receptor activation enhances the activities of two types of Ca2+-activated k+ channels in rat hippocampal astrocytes. 1262 72


1 2 3 Next >>

---