Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Angiotensin II (Ang II) stimulates pathologic myocardial fibrosis. Cardiac fibroblasts (CFb) and myofibroblasts mediate this response, perhaps in part by indirect production of specific cytokines. We sought to determine if Ang II could stimulate transforming growth factor-beta1 (TGF-beta1) gene expression and protein production in adult rat CFb and two cardiac myofibroblast cell types, scar myofibroblasts (MyoFb) and valvular interstitial cells (VIC). Confluent CFb, MyoFb, and VIC in serum-deprived (0.4% FCS) media were treated with Ang II (10(-7) m for CFb; 10(-9) m for MyoFb, VIC) for 24 h. Untreated cells served as controls. Culture media was collected and TGF-beta1 levels determined in triplicate using a sandwich ELISA. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis was performed to determine TGF-beta1 mRNA expression. Ang II increased CFb (P<0.02) and VIC (P<0.04) TGF-beta1 mRNA expression, while the increase in MyoFb was not statistically significant. MyoFb produced the highest TGF-beta1 levels under control conditions compared to VIC and CFb. Ang II stimulated further TGF-beta1 secretion in VIC and CFb, but not MyoFb. The AT1 receptor antagonist Losartan (10(-7) m) greatly attenuated Ang II-stimulated TGF-B1 secretion and decreased TGF-beta1 immunostaining in VIC. The AT2 receptor antagonist PD123177 (10(-7) m) also decreased secretion and immunostaining of TGF-beta1 in VIC, but to a lesser extent than Losartan. TGF-beta1 secretion by MyoFb was unaffected by Losartan and PD123177, although TGF-B1 immunostaining was absent or greatly decreased, respectively, compared to Ang II-treated MyoFb. Ang II stimulates TGF-beta1 gene expression and/or protein production in cardiac fibroblast-like cells which may act as an autocrine/paracrine stimulus to collagen formation. Furthermore, TGF-beta1 production and secretion in these cells can be modulated by specific Ang II receptor antagonists, suggesting a potential benefit in preventing/attenuating pathologic myocardial fibrosis.
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PMID:Angiotensin II stimulated expression of transforming growth factor-beta1 in cardiac fibroblasts and myofibroblasts. 923 48

In this study we showed, for the first time, the existence of a moderate density of specific angiotensin II (Ang II) binding sites (Kd=3.9+/-1.7 nM and Bmax=467.2 130.0 fmol/mg protein) in plasma membrane preparations from rat thyroid gland. Reverse transcriptase/polymerase chain reactions, using primers based on the cloned AT1 and AT2 receptor subtypes, and pharmacological characterization, using the Ang II receptor subtype antagonists Losartan and PD 123319, revealed that these Ang II binding sites match with the AT1 receptor subtypes. To obtain more information on the molecular structure of this Ang II receptor, immunoblotting analyses were carried out using a polyclonal rabbit anti-AT1 antiserum. Western analysis of fresh plasma membrane preparations from thyroid tissue showed three prominent bands of approximately 60, 45 and 40 kDa which appear to be related to different degrees of glycosylation of the receptor molecule. The functional significance of the Ang II receptors in thyroid gland is currently not known. Nevertheless, since Ang II receptors play a pivotal role in the co-ordinated actions of the renin-angiotensin system (RAS), our findings support a reciprocal regulation of thyroid function by the RAS.
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PMID:Characterization of angiotensin II receptors (binding and mRNA) in the rat thyroid gland. 968 52

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.
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PMID:Angiotensin-converting enzyme and angiotensin II receptor subtype 1 inhibitors restitute hypertensive internal anal sphincter in the spontaneously hypertensive rats. 1664 68

Epigenetic mechanisms such as chromatin histone H3 lysine methylation and acetylation have been implicated in diabetic vascular complications. However, histone modification profiles at pathologic genes associated with diabetic nephropathy in vivo and their regulation by the angiotensin II type 1 receptor (AT1R) are not clear. Here we tested whether treatment of type 2 diabetic db/db mice with the AT1R blocker losartan not only ameliorates diabetic nephropathy, but also reverses epigenetic changes. As expected, the db/db mice had increased blood pressure, mesangial hypertrophy, proteinuria, and glomerular expression of RAGE and PAI-1 vs. control db/+ mice. This was associated with increased RNA polymerase II recruitment and permissive histone marks as well as decreased repressive histone marks at these genes, and altered expression of relevant histone modification enzymes. Increased MCP-1 mRNA levels were not associated with such epigenetic changes, suggesting post-transcriptional regulation. Losartan attenuated key parameters of diabetic nephropathy and gene expression, and reversed some but not all the epigenetic changes in db/db mice. Losartan also attenuated increased H3K9/14Ac at RAGE, PAI-1, and MCP-1 promoters in mesangial cells cultured under diabetic conditions. Our results provide novel information about the chromatin state at key pathologic genes in vivo in diabetic nephropathy mediated in part by AT1R. Thus, combination therapies targeting epigenetic regulators and AT1R could be evaluated for more effective treatment of diabetic nephropathy.
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PMID:Losartan reverses permissive epigenetic changes in renal glomeruli of diabetic db/db mice. 2408 54