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:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Endotoxin-mediated macrophage synthesis of nitric oxide (NO) is associated with immune effector function, intercellular communication, leukocyte adhesion, vascular integrity, and neurotransmission. However, little is known of the cellular receptor and signal transduction pathway by which endotoxin induces NO production. With the use of a model of ANA-1 murine macrophages, we stimulated NO production by incubation with increasing concentrations of endotoxin and 5% fetal calf serum. In selected instances, the anti-CD14 antibody, ED9, was added. Endotoxin-mediated NO synthesis was dependent on CD14 function and the presence of an additional serum factor. Endotoxin treatment increased plasma membrane GTPase activity and 35S-labeled guanosine 5'-O-(3-thiotriphosphate) ([35S]GTP gamma S) binding. Conversely, coincubation of cells with endotoxin and the heterotrimeric G protein inhibitors, suramin and guanosine 5'-O-(2-thiodiphosphate) trilithium salt, was associated with decreased NO synthesis, plasma membrane GTPase activity, and [35S]GTP gamma S binding. Blockade of CD14 or G protein function was associated with ablation of endotoxin-mediated inducible NO synthase (iNOS) protein expression, iNOS mRNA levels, and iNOS gene transcription, as determined by immunoblot, reverse transcriptase-polymerase chain reaction, and nuclear run-on analyses, respectively. These results indicate that endotoxin-mediated NO synthesis is a CD14-heterotrimeric G protein-dependent process.
...
PMID:CD14-dependent mechanism for endotoxin-mediated nitric oxide synthesis in murine macrophages. 931 24

In the present study, the angiotensin II receptor subtype I-a (AT1a) and I-b (AT1b) mRNA levels in aortic smooth muscle (ASM), ventricular myocardium (VM) and adrenal from 12-week-old stroke-prone spontaneously hypertensive rats (SHRsp) and age-matched Wistar-Kyoto (WKY) rats with normal diet (control) and high salt-loading were examined by reverse transcriptase-polymerase chain reaction (RT-PCR). The results showed that: (1) The AT1a and AT1b mRNA levels in ASM and VM from SHRsp were lower than those from WKY rats (in ASM, 10% and 23%, while in VM, 23% and 40% lower, respectively). In contrast, both AT1a and AT1b mRNA levels in adrenal from SHRsp were higher (176% and 157%, respectively). (2) In the WKY rats with high salt-loading, the AT1a and AT1b mRNA levels in adrenal, as well as AT1b mRNA level in VM, increased significantly, as compared with the control (in adrenal, 167% and 401%, while in VM, 62%). However, the AT1a and AT1b mRNA levels in ASM, as well as AT1a mRNA level in VM, showed no obvious change. (3) In SHRsp with high salt-loading, the AT1b mRNA level in ASM, as well as AT1a and AT1b mRNA levels in VM, increased markedly (in ASM, 90%, while in VM, 590% and 200%); whereas the AT1a mRNA level in adrenal decreased significantly (58%). There was little influence on the regulation of AT1a (in ASM) and AT1b (in adrenal) receptor gene expression after high salt-loading. The results suggest that AT1a and AT1b receptors may be involved in the pathogenesis of salt-induced hypertension. The up-regulation of AT1b receptors in ASM may induce the remodeling of arterial wall, while that of AT1a and AT1b receptors in VM might contribute to ventricular hypertrophy in hypertension. Furthermore, there are certain differences between SHRsp and WKY rats with respect to the regulation of AT1a and AT1b receptor gene expression with or without external stimulation.
...
PMID:[Effects of high salt-loading on the regulation of angiotensin II receptor mRNA expression]. 938 99

Telomerase is a unique reverse transcriptase involved in the maintenance of genomic integrity. In an attempt to understand the properties of this enzyme and to study the effect of deoxynucleoside analogues, we have isolated and partially purified telomerase from the blast cells of a patient with acute myelogenous leukemia. During the course of purification of telomerase, three characteristic forms of this enzyme activity were separated. Two processive forms and one less processive form were noted. All forms of the enzyme activities could be abolished by RNase A and proteinase K treatments, implying that they are ribonucleoproteins. The major form of telomerase was characterized with respect to divalent ion requirements, effect of salt and nonionic detergents. The Km of deoxynucleoside triphosphates was determined with a modified telomerase repeat array protocol assay. Studies with deoxynucleoside analogues indicated that 3'-azido-3'deoxythymidine triphosphate is much more inhibitory than 2',3'-dideoxy 2',3'didehydrothymidine triphosphate, and the cytidine analogue ddCTP was not inhibitory. ddGTP was the most potent inhibitor among all dideoxynucleosides studied.
...
PMID:Telomerase from human leukemia cells: properties and its interaction with deoxynucleoside analogues. 958 32

Angiotensin II (ANG II), acting through angiotensin type 1A receptors (AT1A), is important in regulating proximal tubule salt and water balance. AT1A are present on apical (AP) and basolateral (BL) surfaces of proximal tubule epithelial cells (PTEC). The molecular mechanism of AT1A function in epithelial tissue is not well understood, because specific binding of ANG II to intact PTEC has not been found and because a number of isoforms of AT receptors are present in vivo. To overcome this problem, we developed a cell line from opossum kidney (OK) proximal tubule cells, which stably express AT1A (Kd = 5.27 nM, Bmax = 6.02 pmol/mg protein). Characterization of nontransfected OK cells revealed no evidence of AT1A mRNA (reverse transcriptase-polymerase chain reaction analysis) or protein (125I-labeled ANG II binding studies) expression. In cells stably expressing AT1A, ANG II binding was saturable, reversible, and regulated by G proteins. Transfected receptors were coupled to increases in intracellular calcium and inhibition of cAMP. To determine the polarity of AT1A expression and function in proximal tubules, transfected cells were grown to confluence on membrane inserts under conditions that allowed selective access to AP or BL surfaces. AT1A were expressed on both AP (Kd = 8.7 nM, Bmax = 3.33 pmol/mg protein) and BL (Kd = 10.1 nM, Bmax = 5.50 pmol/mg protein) surfaces. Both AP and BL AT1A receptors underwent agonist-dependent endocytosis (AP receptor: t1/2 = 7.9 min, Ymax = 78.5%; BL receptor: t1/2 = 2.1 min, Ymax = 86.3%). In cells transfected with AT1A, ANG II caused time- and concentration-dependent increases in transepithelial 22Na transport (2-fold over control at 20 min) by increasing Na/H exchange. In conclusion, we have established a stable proximal tubule cell line that expresses AT1A on both AP and BL surfaces, undergoes agonist-dependent receptor endocytosis, and is functional, as evidenced by inhibition of cAMP and increases in cytosolic calcium mobilization and transepithelial sodium movement. This cell line should prove useful for understanding the molecular and biochemical regulation of AT1A expression and function in PTEC.
...
PMID:Angiotensin (AT1A) receptor-mediated increases in transcellular sodium transport in proximal tubule cells. 961 27

To assess the chronic in vivo effects of OPC-21268, a vasopressin-V1 receptor antagonist, on renal injury, we investigated the mRNA expressions of platelet-derived growth factor (PDGF) B-chain, transforming growth factor (TGF)-beta1 and proliferating cell nuclear antigen (PCNA) in the glomeruli of spontaneously hypertensive rats (SHR) treated with OPC-21268 for 3 weeks. SHR aged 10 weeks were given 2% NaCl in drinking water for 3 weeks. The OPC group was fed a 0.5% OPC-21268-containing diet for 3 weeks and the control group was given a normal diet. There were no significant changes in the time course of systolic blood pressure, heart rate, urine volume, or urinary sodium, protein and N-acetyl-beta-glucosaminidase (NAG) excretion between the two groups. Serum electrolytes, protein and creatinine levels also did not differ between the groups. The mRNA expressions of PDGF B-chain, TGF-beta1 and PCNA in the glomerulus were examined using reverse transcriptase-polymerase chain reaction (RT-PCR) methods. The mRNA expressions of PDGF B-chain and PCNA among these were significantly suppressed in the OPC group. No significant differences in renal histology including the organ weights were found between the two groups; however, the glomerular size tended to be enlarged in the OPC group. These findings suggest that chronic V1-receptor blockade directly inhibits the glomerular proliferative injury of salt-loaded SHR at the established hypertension stage.
...
PMID:Effects of OPC-21268, a vasopressin V1-receptor antagonist, on expression of growth factors from glomeruli in spontaneously hypertensive rats. 965 81

Sheep mast-cell proteinase-1 (sMCP-1) is a serine proteinase expressed predominantly by mucosal mast cells, with specificity for cleavage C-terminal to basic and hydrophobic amino acid residues. A cDNA encoding sMCP-1 has been cloned using reverse transcriptase (RT)-PCR. It appears to be translated as a pre-proenzyme with a 17-amino-acid signal peptide, a basic 2-amino-acid propeptide and a 226-amino-acid catalytic domain. A second cDNA, encoding a serine proteinase 90% identical with sMCP-1, was also cloned and named sMCP-3. Molecular models were constructed for both enzymes using coordinates for the refined X-ray structures of human cathepsin G, chymase and rat mast-cell proteinase-2. The model for sMCP-1 suggests that the acidic Asp-226 side chain extends into the substrate-binding pocket, hydrogen-bonding with Ser-190 on the opposite side and bisecting the pocket. The location of an acidic moiety in this position would favour interaction with basic substrate residues and binding of aromatic residues is rationalized by interaction of the positively charged equatorial plane with Asp-226. The balance between chymotryptic and tryptic activities of sMCP-1 was found to be sensitive to salt concentration, with increasing univalent cation concentration favouring chymotryptic activity relative to the tryptic. Using a peptide substrate representing residues 36-59 of the human thrombin receptor, increasing salt concentration favoured cleavage at Phe-43 rather than at Arg-41.
...
PMID:Sheep mast-cell proteinases-1 and -3: cDNA cloning, primary structure and molecular modelling of the enzymes and further studies on substrate specificity. 967 43

Expression of the isiA and isiB genes was analysed in the cyanobacterium Synechocystis sp. PCC 6803 grown in high salt or in iron-deficient medium. The detection of a 2.3-knt transcript in Northern blot experiments indicated cotranscription of isiAB in an operon, which was confirmed by reverse transcriptase PCR. The abundance of a monocistronic 1.25-knt isiA-specific mRNA was about 10-fold higher than the dicistronic message. The isiAB-specific transcripts were most abundant in cells adapted to 342 mM NaCl and under iron deficiency. The promoter of the operon was mapped to 211 bp upstream of the translational start. A putative Fur binding site was detected immediately upstream of the GTG start codon. A preliminary transcript of about 0.2 knt was detected in cells grown in conditions in which the isiAB operon was not transcribed. This indicates that a repressor binds to the identified Fur binding site and thus inhibits isiAB transcription under low salt and iron replete conditions.
...
PMID:Transcriptional analysis of the isiAB operon in salt-stressed cells of the cyanobacterium Synechocystis sp. PCC 6803. 986 77

Epithelial Na+ channels (ENaCs) are thought to mediate the amiloride-blockable salt taste. The rat vallate papilla does not contribute to amiloride-blockable salt taste, yet the presence of ENaC-mRNA in this tissue has been reported. Is ENaC actually contained in the taste cells, or is it merely present in the supporting lingual epithelium? To avoid contamination by ENaC contained in the lingual epithelium, we physically isolated taste buds from the vallate papilla and used mRNA purification followed by reverse transcriptase polymerase chain reaction (RT-PCR) to investigate the presence of ENaC-type message in the isolated buds. mRNA of alpha-, beta- and gamma-subunits was detected, the alpha-signal being the strongest. These results provide first molecular evidence for the presence of ENaC subunits in taste buds that were isolated from the posterior tongue and were free of epithelial contamination. In addition, we used immunohistochemistry to show ENaC-like reactivity in posterior tongue taste cells. Interestingly, the immunoreactivity was not predominantly apical but was intracellular and close to or at the basolateral membrane. The function of basolateral ENaC-type channels is unknown. Possibly, the channels are normally closed or of very low open probability in the resting state.
...
PMID:Occurrence of ENaC subunit mRNA and immunocytochemistry of the channel subunits in taste buds of the rat vallate papilla. 992 92

This study tests the hypothesis that aldosterone induces cardiac fibrosis through an increase of cardiac angiotensin II (Ang II) AT1 receptor levels, thereby potentiating the fibrotic effect of Ang II by determining the effects of spironolactone and losartan on cardiac fibrosis, AT1 density, and gene expression in aldosterone-salt-treated rats. Fibrosis was quantified by slot blots of collagen I and III mRNA levels and videomorphometry of Sirius red-stained collagen. AT1 receptor density was determined by (125I-Sar1-Ile8)-Ang II competition binding, and AT1 mRNA levels were analyzed by quantitative reverse transcriptase polymerase chain reaction. One month of aldosterone-salt treatment induced a decrease in plasma Ang II and an increase in blood pressure, left ventricular hypertrophy, and ventricular fibrosis. Spironolactone (20 mg/kg per day) and losartan spironolactone (10 mg/kg per day) had no effect on the first 3 parameters. Losartan was as effective as spironolactone in preventing ventricular collagen mRNA increase and fibrosis. Ventricular density of AT1 receptors increased 2-fold and was accompanied by a 3-fold increase in the corresponding mRNA in aldosterone-salt compared with sham-operated rats. Both spironolactone and losartan prevented the elevation of ventricular AT1 density and that of right ventricular AT1 mRNA levels. These results demonstrate that the mechanism by which aldosterone-salt induces cardiac fibrosis involves Ang II acting through AT1 receptors. They also suggest that the cardiac AT1 receptor is a target for aldosterone.
...
PMID:Angiotensin AT1 receptor subtype as a cardiac target of aldosterone: role in aldosterone-salt-induced fibrosis. 1020 34

The effect of 44 different metal ions (Ag+, Al3+, As(O-)2, Au3+, Ba2+, Be2+, Bi3+, Cd2+, Ce3+, CO2+, Cr(O2-)4, Cr3+, Cs+, Cu2+, Fe3+, Fe2+, Ga3+, Ge4+, Hg2+, Ir4+, La3+, Li+, Mn2+, MO6+, Ni2+, OS4+, Pb2+, Pt4+, Rb+, Rh3+, Sb5+, Se(O2-)4, Se(O2-)3, Sn2+, Sr2+, Th4+, T1+, U(O2+)2, V(O-)3, VO2+, W(O2-)4, Y3+, Zn2+, and Zr4+) on the activity of the reverse transcriptase (RT) of the human immunodeficiency virus (HIV-1) was investigated in vitro. For this study, the RT activity assay was carried out by means of an enzyme-linked immunosorbent assay (ELISA) kit, using the template/primer hybrid poly(A) oligo(dT)15, which required some modifications: (1) possible interfering metal chelators (such as EDTA) in the original lysis buffer were avoided, and a new buffer (50 mM Tris-NO3, pH 7.8) was used throughout; (2) an amount of 2 ng of RT per well was considered to be optimal after checking the linearity of the reaction with increasing amounts of enzyme; (3) an incubation temperature of 37 degrees C and an incubation time of 1 h were chosen after preliminary studies in a wide range of temperature and time. At an incubation temperature > or = 40 degrees C, there was a dramatic loss of enzymatic activity. In addition, when RT alone was preincubated for 1 h at 5 degrees C, 25 degrees C, and 37 degrees C, there was a large (83%) loss of activity at 37 C as compared to that at 5 degrees C. These results are indicative of enzyme thermolability, which is higher in the absence of substrates. The effect of metal ions on RT activity was tested using two different metal salt concentrations (10(-4) M and 10(-5) M). Under such experimental conditions, the presence of five metal ions (Pt4+, Ag+, Rh3+, Zn2+, and Hg2+) decreased the RT activity in a dose-response fashion. The observed order of effectiveness with respect to inhibition was Pt4+ > Ag+ > Rh3+ > Zn2+ = Hg2+. Estimated mean inhibitory concentrations (IC50) were 7.8 microM for (NH4)2PtCl6, 14.1 microM for AgNO3, 46.8 microM for RhCl3, 53.7 microM for Zn(SO)4, and 56.2 microM for Hg(NO3)2. Because these data are of the same order of magnitude as the corresponding values related to other RT inhibitors used in anti-AIDS therapy, metal compounds or their derivatives could give an interesting contribution in the development of new RT inhibitors for clinical use.
...
PMID:Effects of trace metal compounds on HIV-1 reverse transcriptase: an in vitro study. 1032 22


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---