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)

We have developed a multiplex, competitive, reverse-transcriptase polymerase chain reaction (RT-PCR) method which measures absolute levels of renin, angiotensinogen, and the housekeeping transcript elongation factor-1 alpha (EF-1 alpha) mRNA. Sample RNA was simultaneously titrated with serial dilutions of renin, angiotensinogen, and EF-1 alpha competitor RNAs which flanked the endogenous concentrations of target transcripts. The samples were coreverse transcribed in the presence of random primers and resulting first-strand cDNA was coamplified for 10-15 cycles with [32P]-dCTP and primers for renin angiotensinogen, after which EF-1 alpha primers were added. Amplified DNA was separated by electrophoresis on polyacrylamide gel and radioactivity in the bands was quantified by direct radioanalytical scanning. Three conditions were necessary to obtain absolute quantification of renin and angiotensinogen mRNA levels: (a) exogenous competitor RNA was used to control for tube-to-tube variability in the efficiencies of reverse transcription and amplification; (b) Sample RNA was titrated with flanking concentrations of competitor RNA to correct for intraassay differences in the efficiency of amplification due to concentration differences between competitor and target templates; and (c) a housekeeping transcript EF-1 alpha was used to control for tube-to-tube differences in RNA loading and/or degradation. We show that the multiplex RT-PCR method is precise and accurate over approximately three logs of transcript concentration and sensitive to less than 5 and 0.5 fg for renin and angiotensinogen mRNA, respectively. This method will be useful for absolute quantification of target mRNAs, especially when the amount of sample RNA is limited or unknown and/or the gene expression is low.
...
PMID:An improved method for absolute quantification of mRNA using multiplex polymerase chain reaction: determination of renin and angiotensinogen mRNA levels in various tissues. 788 70

This study was designed to quantitate cardiac mRNA levels encoding components of the local renin-angiotensin system during the development of volume overload-induced cardiac hypertrophy. Changes in cardiac renin mRNA levels were measured in relation to renin activity in the left ventricle (LV) and in plasma after acute passive stretch of the heart caused by an aortovenocaval shunt in the rat. A quantitative reverse-transcriptase polymerase chain reaction method with competitive internal standards was used to measure mRNA levels in total RNA derived from cardiac tissues after shunt. Seven days after shunt surgery, LV weight was increased by 23%. Renin activities were elevated four- and twofold in plasma and LV, respectively. LV angiotensinogen mRNAs were not significantly increased by shunt surgery; they were twofold higher than phosphoglycerate kinase mRNA from the housekeeping gene PGK-1. By day 7, LV levels for renin mRNA were significantly increased from well below 0.25% to approximately 1% of PGK-1 mRNA. Identity between renin polymerase chain reaction products from kidney and heart cDNAs and absence of "reninlike" amplification products were supported by Southern blotting. Volume overload caused increased expression of the renin gene in the stretched myocardium. This finding is consistent with the concept of a myocardial renin-angiotensin system that can be activated by locally produced renin and contributes to the hypertrophy of cardiac muscle.
...
PMID:Stretch-mediated activation of cardiac renin gene. 794 10

Using reverse-transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry we investigated the ontogeny of renin, angiotensinogen and angiotensin converting enzyme (ACE) in the mesonephros at 27 and 41 days of gestation, and the metanephros at 41 and 64 days of gestation in ovine fetuses (term is 145 to 150 days). The volume and composition of fetal urine, stored as allantoic fluid were measured in 12 fetuses at 27 days, and 13 fetuses at 41 days. Renin, angiotensinogen and ACE were identified in both meso- and metanephroi at 41 days but not in the mesonephros at 27 to 30 days. Allantoic fluid volumes were 21 +/- 3 and 45 +/- 5 ml at 27 to 30 days and 41 days, respectively. This fluid was significantly different in composition to that of amniotic fluid or maternal plasma. The results suggest that the mesonephros can substantially modify its glomerular filtrate by 27 days of gestation, and can produce local angiotensin II by 41 days.
...
PMID:Ontogeny of hormonal and excretory function of the meso- and metanephros in the ovine fetus. 891 29

All the angiotensin peptides originate from angiotensinogen, a glycoprotein synthesized by several tissues, including the brain and the anterior pituitary. In the rat, immunohistochemistry has been used to localize angiotensinogen in gonadotropes and in uncharacterized cells surrounding sinusoids. Both cell types are capable of secreting angiotensinogen in cell culture; only the gonadotropes contain angiotensin II (AngII) and are capable of secreting it in culture. It has been asserted that the perisinusoidal cells are the only source of angiotensinogen for the generation of AngII by gonadotropes. Our current data favor the existence of a complete intracellular renin-angiotensin system (RAS) in gonadotropes and a separate extracellular system which utilizes the high concentration of angiotensinogen from perisinusoidal cells. Furthermore, we postulate that gonadotrope AngII serves mainly reproductive functions, while the proximity of angiotensinogen-secreting cells to folliculostellate cells, and their access to the intercellular sinusoidal and follicular spaces, places the extracellular RAS in a strategic position to affect pituitary growth and the mediation of acute-phase immune responses. In the rat brain, angiotensinogen is expressed by the 16-18th day of fetal life and by areas generally concerned with vasopressor, electrolyte, and fluid homeostasis. Antisense deoxyoligonucleotides to angiotensinogen mRNA lower blood pressure in hypertensive rats and inhibit in vitro growth of neuroblastoma cells, indicating a significant role for angiotensinogen in mitogenic and homeostatic functions. It is commonly agreed that astrocytes express angiotensinogen. Neuronal angiotensinogen has also been demonstrated by immunohistochemistry, as a secretion from neuronal cell cultures, and by reverse-transcriptase polymerase chain reaction. The fate of secreted astrocytic and neuronal angiotensinogen remains obscure. Angiotensinogen is regulated in a tissue-specific manner with smaller or absent responses observed for brain tissue. By using astrocyte and neuronal cultures the actions on angiotensinogen production of growth hormone, IGF-1, inflammatory lipopolysaccharide, and phorbol ester have been examined. Recent observations show that angiotensinogen is regulated positively or negatively by glucocorticoids and that a positive synergism between cAMP and glucocorticoids exists. On the basis of analogous systems for other proteins, a scheme involving glucocorticoid receptors, CREB, and AP-1 transcription factors is formulated to explain glucocorticoid-cAMP interactions. These transcriptional interactions may form a significant functional link between the RAS and adrenergic mechanisms.
...
PMID:Novel perspectives on pituitary and brain angiotensinogen. 910 Dec 59

Previous studies have suggested the presence of an intrinsic renin-angiotensin system (RAS) in the rat epididymis with functions in epididymal activity and sperm maturation. In the present study, the localization and expression of angiotensinogen, the component of the RAS which is indispensable for intracellular angiotensin generation, were investigated by immunochemistry, hybridization histochemistry and by reverse-transcriptase polymerase chain reaction (RT-PCR). Western blot analysis of protein from the epididymis confirmed the presence of angiotensinogen with the expected molecular mass of about 60 kDa, in agreement with results from other tissues. Immunocytochemistry showed the regional localization of immunoreactivity for angiotensinogen in the rat epididymis. In situ hybridization histochemistry further demonstrated the expression of angiotensinogen mRNA by the epididymal epithelium in a region-specific manner along the length of the rat epididymis. RT-PCR confirmed that the rat epididymis expresses angiotensinogen mRNA. On the other hand, mRNA of renin was not detected in the rat epididymis using Northern blot and RT-PCR analyses. The present study strongly supports the existence of an intrinsic, angiotensin-generating system based on locally formed angiotensinogen as a precursor for angiotensin production. This epididymal RAS may have paracrine or autocrine roles in mediating the epididymal and sperm functions.
...
PMID:Angiotensinogen expression by rat epididymis: evidence for an intrinsic, angiotensin-generating system. 1058 Aug 44

The presence of a local renin-angiotensin system has been established in organs that serve as angiotensin targets. In this study, the expression of angiotensinogen mRNA and subcellular localization of renin, angiotensin-converting enzyme, and angiotensin II were investigated in bovine adrenal medullary cells in primary culture. By light microscopy, expression of angiotensinogen mRNA, immunoreactive renin, angiotensin-converting enzyme, and angiotensin II were readily detectable only in the chromaffin cells. The density distribution of renin and angiotensin II in sucrose gradients suggested a concentration in chromaffin granules, a localization directly confirmed by immunoelectron microscopy. Reverse transcriptase-polymerase chain reaction and sequencing confirmed the expression of angiotensinogen in bovine chromaffin cells and the adrenal medulla. In addition, in vitro autoradiography indicated that both angiotensin-converting enzyme and angiotensin type 1 receptors were present in the adrenal medulla. These results provide the first direct evidence that chromaffin cells in the adrenal medulla are not only the target for angiotensin but should also be considered as potential local angiotensin-generating and -storing cells.
...
PMID:Presence of cellular renin-angiotensin system in chromaffin cells of bovine adrenal medulla. 1238 58

The present study determined the effects of the angiotensin-converting enzyme (ACE) inhibitor captopril and angiotensin II receptor subtype 1 (AT1-R) antagonist losartan on the internal anal sphincter pressures (IASP) in spontaneously hypertensive rats (SHR) versus normotensive Wistar-Kyoto rats (WKY). The SHR had significantly higher IASP (21.7 +/- 0.8 mm Hg) than the WKY (14.7 +/- 0.9 mm Hg), which was associated with the higher levels of angiotensin II (Ang II) in plasma (50.3 +/- 0.9 pg/ml) and in muscle bath perfusates (72.7 +/- 11.8 pg/ml) compared with the WKY (p < 0.05). Captopril and losartan decreased the IASP in SHR and WKY, but they were more potent in SHR. Captopril and losartan normalized the IASP in the SHR, whereas these agents may compromise rectoanal continence in the WKY. Reverse transcriptase-polymerase chain reaction and Western blots showed higher levels of angiotensinogen, renin, ACE, and AT1-R in the internal anal sphincter (IAS) of SHR. Ang II caused concentration-dependent contraction of IAS smooth muscle strips from WKY (pEC50 = 8.5 +/- 0.1) and SHR (pEC50 = 8.6 +/- 0.2). Losartan (100 nM) significantly (p < 0.05) inhibited this effect. From these data, we conclude that 1) hypertensive IAS in SHR is primarily the result of renin-angiotensin system up-regulation, 2) ACE inhibitors and AT(1)-R antagonists simply relieve the hypertensive IAS, and 3) the differential effect of these inhibitors in the hypertensive versus the normotensive IAS may explain the lack of incontinence as a side effect in hypertensive patients receiving ACE inhibitors and AT1-R antagonists.
...
PMID:Angiotensin-converting enzyme and angiotensin II receptor subtype 1 inhibitors restitute hypertensive internal anal sphincter in the spontaneously hypertensive rats. 1664 68

This study was aimed at investigating the effects of Angiotensin (Ang) II stimulation on T lymphocytes mRNA expression of angiotensinogen (AGTN), angiotensin-converting enzyme (ACE) and AT1-receptor (R) and on ACE activity and Ang II content. The effects of Ang II stimulus were studied in lipopolysaccharide (LPS)-stimulated or not stimulated lymphocytes. mRNA expression for interferon-gamma (INF-gamma) was also studied to investigate whether a link between lymphocyte RAS and immunological function might occur. mRNAs for AGTN, ACE and AT1-R were obtained from peripheral blood of 18 healthy subjects and were quantified by real time quantitative transcriptase-polymerase chain reaction (PCR). ACE activity was assayed in cell pellets and supernatants by measuring the hippuric acid formation by high performance liquid chromatography (HPLC) and Ang II cell content was measured by radioimmunoassay (RIA) after HPLC separation. All determination were performed under baseline conditions and after the addition of 10(e- 13) M Ang II to LPS-stimulated or unstimulated lymphocytes. Ang II caused a significant upregulation of T subset lymphocytes gene expression of ACE and AT1-R and of INF gamma, and a marked increase in ACE activity and cell Ang II concentration. AGTN gene was never expressed. All these effects were further enhanced in T lymphocytes presitmulated by LPS and completely inhibited by Irbesartan. Our findings strongly support the evidence of a positive Ang II driven autocrine loop that upregulates cell RAS of isolated lymphocytes and activates the immuno response. The immuno-potentiating effect of Ang II, specifically shown in T subset, can be deleterious when local RAS are disregulated as in cardiovascular atherosclerotic disease.
...
PMID:Angiotensin II upregulates renin-angiotensin system in human isolated T lymphocytes. 1872 52

---