Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Major epidemic outbreaks of viral hepatitis in underdeveloped countries result from a type of non-A, non-B hepatitis distinct from the parenterally transmitted form. The viral agent responsible for this form of epidemic, or enterically transmitted non-A, non-B hepatitis (ET-NANBH), has been serially transmitted in cynomolgus macaques (cynos) and has resulted in typical elevation in liver enzymes and the detection of characteristic virus-like particles (VLPs) in both feces and bile. Infectious bile was used for the construction of recombinant complementary DNA libraries. One clone, ET1.1, was exogenous to uninfected human and cyno genomic liver DNA, as well as to genomic DNA from infected cyno liver. ET1.1 did however, hybridize to an approximately 7.6-kilobase RNA species present only in infected cyno liver. The translated nucleic acid sequence of a portion of ET1.1 had a consensus amino acid motif consistent with an RNA-directed RNA polymerase; this enzyme is present in all positive strand RNA viruses. Furthermore, ET1.1 specifically identified similar sequences in complementary DNA prepared from infected human fecal samples collected from five geographically distinct ET-NANBH outbreaks. Therefore, ET1.1 represents a portion of the genome of the principal viral agent, to be named hepatitis E virus, which is responsible for epidemic outbreaks of ET-NANBH.
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PMID:Isolation of a cDNA from the virus responsible for enterically transmitted non-A, non-B hepatitis. 210 74

Our aim was to characterize and determine the function of endothelin (ET) receptor subtypes in human vascular tissue. Reverse transcriptase-polymerase chain reaction with nested oligonucleotide primers detected the presence of mRNA encoding both ETA and ETB receptors in the media from aorta and pulmonary and coronary arteries. In situ hybridization confirmed the presence of mRNA for both subtypes in the media of coronary arteries. Saturation binding assays using 125I-ET-1 found a single population of high-affinity ET receptors (n = three patients, +/- SEM) in aorta (Kd = 0.507 +/- 0.020 nM; Bmax = 9 +/- 4 fmol/mg protein) and pulmonary (Kd = 0.845 +/- 0.245 nM; Bmax = 15 +/- 10 fmol/mg protein) and coronary arteries (Kd = 0.141 +/- 0.020 nM; Bmax = 71 +/- 21 fmol/mg protein). Using media from coronary arteries, the ETA-selective ligand BQ123 (cyclo[D-Asp-L-Pro-D-Val-L-Leu-D-Trp]) and the ETB-selective ligand BQ3020 (Ala11,15-Ac-ET-1[6-21]) both produced biphasic competition binding curves against 125I-ET-1, confirming the presence of high- and low-affinity sites corresponding to the two subtypes: BQ123 (KdETA = 0.85 +/- 0.03 nM; KdETB = 7.58 +/- 2.27 microM; ETA/ETB, 87%:13%) and BQ3020 (KdETA = 0.22 +/- 0.04 microM; KdETB = 0.77 +/- 0.34 nM; ETA/ETB, 62%:38%). BQ123 (0.1 microM) caused a significant parallel rightward shift of ET-1-induced vasoconstriction of coronary arteries in vitro, but BQ3020 and Ala1,3,11,15-ET-1 failed to show any agonist activity when tested at concentrations of < or = 3 microM in three vessels.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Human endothelin receptors characterized using reverse transcriptase-polymerase chain reaction, in situ hybridization, and subtype-selective ligands BQ123 and BQ3020: evidence for expression of ETB receptors in human vascular smooth muscle. 750 50

1. Endothelin (ET) has been implicated in cerebrovasospasm for example, following subarachnoid haemorrhage, and blocking the interaction of ET with its receptors on cerebral vessels, may be of therapeutic benefit. The aim of our study was to characterize endothelin receptor sub-types on medial smooth muscle cells of human cerebral vessels. Cultures of vascular smooth muscle cells were explanted from human cerebral resistance vessels and characterized as human brain smooth muscle cells (HBSMCs). 2. Over a 48 h incubation period, HBSMC cultures secreted comparable levels of immunoreactive (IR) big endothelin-1 (big ET-1) and IR endothelin (ET): 12.7 +/- 10.3 and 8.3 +/- 5.6 pmol/10(6) cells, respectively (mean +/- s.e. mean from three different individuals), into the culture medium. 3. Total RNA was extracted from cultures of human brain smooth muscle cells. Reverse-transcriptase polymerase chain reaction (RI-PCR) assays and subsequent product separation by agarose gel electrophoresis revealed single bands corresponding to the expected product sizes encoding cDNA for ETA (299 base pairs) and ETB (428 base pairs) (n = 3 different cultures). 4. Autoradiography demonstrated the presence of specific binding sites for [125I]-ET-1 which labels all ET receptors, and [125I]-PD151242, an ETA subtype-selective antagonist which exclusively labels ETA receptors, but no specific-binding was detected using ETB subtype-selective [125I]-BQ3020 (n = 3 different cultures, in duplicate). 5. In saturation binding assays, [123I]-ET-1 bound with high affinity: KD = 0.8 +/- 0.1 nM and Bmax = 690 +/- 108 fmol mg-1. A one-site fit was preferred and Hill slopes were close to unity over the concentration range (10(-12) to 10(-8) M). [125I]-PD151242 also bound with similar affinity: KD = 0.4 +/- 0.1 nM and Bmax = 388 +/- 68 fmol mg-1 (mean +/- s.e. mean, n = 3 different cultures). Again, a one-site fit was preferred and Hill slopes were close to unity over the concentration range. Unlabelled PD151242 competed for the binding of [125I]-ET-1 monophasically and analysis of the competition curves indicated that a one-site fit was preferred over a two-site model, implying that the cultures express mainly ETA receptors. 6. Although messenger RNA encoding both ETA and ETB receptors was detected, autoradiographical analysis, as well as binding studies indicate that human cultured brain smooth muscle cells express only ETA receptor protein. Antagonism of this sub-type may be necessary to block the actions of ET-1 in the human cerebral resistance vessels in the vasospasm observed subsequent to subarachnoid haemorrhage.
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PMID:Endothelin ETA receptor expression in human cerebrovascular smooth muscle cells. 858 Dec 82

We investigated the synthesis and localization of endothelin isoforms in the human kidney using the reverse-transcriptase polymerase chain reaction (RT-PCR) and immunocytochemistry. PCR products corresponding to the expected size for mRNA encoding ET-1, ET-2 and ET-3 were found in homogenates of renal medulla, cortex and vessels from each of five individuals. Using four rabbit polyclonal antibodies to assess the distribution of mature ET, Big ET-1, Big ET-2 and Big ET-3 immunoreactivity in the human kidney, mature IR ET localized to the cytoplasm of endothelial cells lining intra-renal blood vessels including interlobular and arcuate arteries, arterioles and adjacent arcuate veins, all of which showed strongly positive staining. IR Big ET-1 co-localized with the mature peptide. No specific staining was detected within these anatomical regions when pre-immune sera were substituted or primary antibody omitted. Mature IR ET also localized to the cytoplasm of endothelial cells within the glomerulus. Other capillary endothelial cells did not stain, and other structures stained only faintly by comparison. IR Big ET-2 and Big ET-3 could not be detected. These results show that human kidney contains mRNA encoding all three peptide isoforms, but only mature ET and Big ET-1 peptides could be detected by immunocytochemical staining. This provides further evidence that ET-1 may function as a renal peptide in humans, as it is locally synthesized within the kidney.
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PMID:Localization of endothelin peptides in human kidney. 882 21

Endothelins (ET) are vasoactive polypeptide hormones that stimulate osteoblastic signal transduction events. Using MC3T3-E1 and primary osteoblasts, we studied ET effects on interleukin-6 (IL-6) and macrophage colony-stimulating factor (M-CSF) production. Enzyme-linked immunosorbent assay analysis showed a dose-dependent 3- to 3.5-fold increase in IL-6 with 100 nM ET-1 stimulation within 4 (primary osteoblasts) to 8 (MC3T3-E1) h. ET-3 was less effective at enhancing IL-6 production, with a maximal twofold increase after 100 nM ET-3 after 4 h. No significant increase in M-CSF production was noted with ET-1 or ET-3 in either cell type. Reverse-transcriptase polymerase chain reaction analysis demonstrated both ET(A) and ET(B) receptors on primary osteoblasts and only ET(A) receptors on MC3T3-E1. ET-1-stimulated IL-6 production was blocked by the inhibitor BQ-123, implicating ET(A) receptor involvement. Increased IL-6 protein was coupled with elevated IL-6 mRNA levels and a twofold increase in IL-6 message half-life.
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PMID:Endothelin stimulates osteoblastic production of IL-6 but not macrophage colony-stimulating factor. 912 53

The endothelins (ET) are a group of three vasoactive peptides also known to be involved in vascular remodeling. ET1 is the most extensively studied, but recent evidence has highlighted the role of the little investigated ET2 gene as a potential candidate gene in regulating blood pressure. To allow the future role of this gene to be studied the structure of human ET2 was characterized and intron/exon boundaries were determined. With this structural information and using reverse-transcriptase PCR technology we show that the ET2 gene is commonly expressed in human right atrial tissue. This work will allow a more detailed assessment of the role of this physiologically important gene in human essential hypertension.
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PMID:Structure of human endothelin-2 gene and demonstration of common expression in human right atrial tissue. 958 79

Sarafotoxin S6c [STXS6c; a selective endothelin-B (ETB) receptor agonist] causes constriction of isolated pulmonary arteries. In perforated-patch experiments on pulmonary arterial myocytes, ET-1 and STXS6c induced a gradual inhibition of the delayed rectifier K current (IKV), the profile of which resembled that carried by Kv1.5. Reverse-transcriptase polymerase chain reaction (RT-PCR) experiments revealed mRNA encoding this channel, and immunolocalization experiments demonstrated expression of the channel protein in pulmonary arterial smooth muscle. It is tempting to speculate that ETB receptor coupling to Kv1.5 may be implicated in contraction after stimulation of these receptors.
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PMID:Endothelin-1, delayed rectifier K channels, and pulmonary arterial smooth muscle. 959 7

The aim of this study was to investigate the involvement of endothelins (ET) in brain injury. The effect of ET was studied in the isolated basilar artery (BA) taken from control, sham-operated, and cold-lesioned rats. Cold lesion was induced by application of a precooled (-78 degrees C) copper cylinder (outer diameter 5 mm) for 60 seconds to the intact dura over the parietal cortex. After precontraction with prostaglandin (PG) F2alpha, ET-3 (10(-10) to 10(-8) mol/L) dilated BA with a pD2 (negative log of the half-maximal concentration) of 9.06+/-0.031 (mean +/- SD) and a maximal effect (Emax) of 1.64+/-1.0 mN at 3 x 10(-9) mol/L in sham-operated animals. This dilation was reduced 24 and 48 hours after cold lesion by 33% and 73%, respectively, at 3 x 10(-9) mol/L. The effects of acetylcholine (10(-8) to 10(-4) mol/L) and sodium nitroprusside (10(-3) mol/L) were unaltered. Activation of the ETB receptor in thoracic aorta by the specific agonist IRL 1620 also resulted in a reduced dilation (51% by 48 hours after cold lesion). Reverse transcriptase-polymerase chain reaction of the BA showed unaltered expression of mRNA for the ETB receptor after cold lesion whereas ETB immunoreactivity in BA and in its intraparenchymal arteries was reduced at 24 and 48 hours. In contrast to the reduction of ET-3-induced dilation, the constrictor effects of ET-1 and ET-3 were retained after cold lesion. Endothelin-1 (10(-12) to 10(-6) mol/L) dose-dependently contracted segments of untreated control BA segments under resting conditions with a pD2 of 8.03+/-0.22 and an Emax of 6.35+/-0.70 mN. Further evidence that the constrictor ability of BA was not influenced by cold lesion is given by the unaltered response to 124 mmol/L K+ and 10(-6) mol/L serotonin. We conclude that the ETB receptor of BA after cold lesion is downregulated specifically, apparently at the posttranscriptional level. Because the ETB-mediated dilation in thoracic aorta was also reduced, downregulation of the ETB receptor apparently is not restricted to cerebral arteries. The nitric oxide-cyclic guanosine monophosphate system in BA is, however, intact.
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PMID:Delayed loss of ETB receptor-mediated vasorelaxation after cold lesion of the rat parietal cortex. 985 Jan 48

Endothelin (ET) receptor antagonists are nephroprotective in renal damage models of the rat. It is unknown whether ET receptor antagonists are also beneficial in human renal diseases. Major differences exist between the ET systems in rats and humans, therefore this study was designed to characterize the ET receptors expressed on human adult mesangial cells (HMCs). HMCs cultures are a surrogate model for the development of glomerulosclerosis. Binding experiments with [125I]ET-1 in the presence or the absence of the test compounds [endothelin-1, -3 (ET-1, ET-3), sarafotoxin 6c (S6c), or BQ123] revealed an affinity (IC50 values) of 10.5 nm for ET-1 and 87.6 nm for ET-3. The affinities of the ET(B) agonist S6c and the ET(A) antagonist BQ123 were 85.9 nm and > 10 microm, respectively. Thus, the ET receptor on HMCs shows an ET(B)-like pharmacology, but in contrast to the classical ET(B)-receptor the affinities are low. No affinity for BQ123 up to > 10 microm excludes the presence of ET(A)-receptors. Functional studies using microfluorimetry (fura-2 method) showed comparable biphasic calcium signals induced by 10 nm ET-1, ET-3 and S6c. This effect could not be inhibited by BQ123, but by the ET(B) antagonist BQ788. Reverse transcriptase polymerase chain reaction (RT-PCR) studies under different culture conditions showed that both ET(A)- and ET(B)-receptor mRNAs are expressed in HMCs. The amount of ET(A)-receptor mRNA increased 2.7-fold and that of the ET(B)-receptor mRNA 7.1-fold after stimulation with 10% fetal calf serum (FCS). ET-1, ET-3 and S6c stimulated HMCs growth (ET-1 > S6c > ET-3), but the magnitude of the effect of ET-1 is lower than reported in rat mesangial cells (rat MCs). The effect on HMCs growth could be inhibited by BQ788, but not by BQ123. Our data provide evidence for the expression of ET(B)-receptors on HMCs that are functionally active. This finding differs from the ET receptor expression in rat MCs as reported by others.
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PMID:Adult human mesangial cells (HMCs) express endothelin-B-receptors which mediate endothelin-1-induced cell growth. 1107 85

Genetic responses that characterize experimental autoimmune myocarditis (EAM) have not yet been determined. To investigate gene expression in the myocardium of EAM, absolute copy numbers of 44 mRNA species [calcium-handling proteins, contractile proteins, natriuretic peptides (NPs), cytokines, chemokines, growth factors, renin-angiotensin-aldosterone (RAA) system, endothelins (ETs) and extracellular matrix] in synthesized cDNA from a fixed quantity of total heart RNA were assessed using real-time reverse-transcriptase PCR at days 0, 14, 21 and 28 after immunization. alpha-Cardiac myosin showed a 26.3-fold decrease and beta-cardiac myosin a 3.75-fold increase at day 14. Atrial NP and brain NP increased 47.7- and 6.35-fold at days 21 and 14 respectively. Angiotensin II type 1 receptor, angiotensin-converting enzyme and ET1 increased 22.3-fold at day 21, 6.30-fold at day 21 and 16.8-fold at day 14 respectively. Aldosterone receptor decreased 2.15-fold at day 14, but aldosterone synthetase was detected only at days 14 and 21. Interleukin (IL)-2, IL-10, interferon-gamma and monocyte chemo-attractant protein-1 increased 9.08-fold at day 14, 398-fold at day 21, 43.1-fold at day 14 and 142-fold at day 14 respectively. Collagen type 3, collagen type 1 and fibronectin increased 34.6-, 1.74- and 44.4-fold respectively at day 21. Interestingly, osteopontin showed a 4540-fold increase and it was the highest mRNA of all at day 14. An isoform of cardiac myosin and NP are dramatically changed in EAM. RAA system and ET expressions are changed differently during the EAM time course. Cytokine, chemokine and extracellular matrix greatly increase and, in particular, large numbers of osteopontin mRNA are expressed in early EAM.
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PMID:Time course of gene expression in rat experimental autoimmune myocarditis. 1244 15


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