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

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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)

HMG-CoA reductase inhibitors (statins) are cholesterol-lowering drugs and reduce the risk of myocardial infarction and stroke. In this study we investigated whether rosuvastatin, a new, potent HMG-CoA reductase inhibitor, upregulates endothelial nitric oxide (NO) expression and activity and protects from cerebral ischaemia in mice. Endothelial cells in culture and 129/SV mice were chronically treated with rosuvastatin. The expression and activity of endothelial NO synthase (eNOS) was determined by reverse-transcriptase polymerase chain reaction (RT-PCR), Western blotting and arginine-citrulline assays. Cerebral ischaemia was induced by occlusion of the middle cerebral artery (MCAo) for 2 h and infarct size was determined after 22 h of reperfusion. Treatment of endothelial cells with rosuvastatin concentration- and time-dependently upregulated eNOS mRNA and protein expression. In aortas of 129/SV wild-type mice, treatment with 0.2, 2, and 20 mg kg(-1) rosuvastatin subcutaneously (s.c.) for 10 days significantly upregulated eNOS mRNA by 50, 142, and 205%, respectively. NOS activity was significantly increased by 75, 145, and 320%, respectively. Stroke volume after 2-h MCAo was reduced by 27, 56, and 50% (for 0.2, 2 and 20 mg kg(-1), respectively). Serum cholesterol and triglygeride levels were not significantly lowered by the treatment. The novel HMG-CoA reductase inhibitor rosuvastatin dose-dependently upregulates eNOS expression and activity and protects from cerebral ischaemia in mice. The effects are independent of changes in cholesterol levels and are equivalent or even superior to the protective effects by simvastatin and atorvastatin in this animal model.
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PMID:Rosuvastatin, a new HMG-CoA reductase inhibitor, upregulates endothelial nitric oxide synthase and protects from ischemic stroke in mice. 1203 49

Selective estrogen receptor modulators (SERMs) are steroidal or nonsteroidal compounds that can exhibit either estrogen-like agonistic effects or estrogen-antagonistic effects depending on the target tissue. While SERM actions in the breast, bone, and uterus have been well characterized, their effects in the brain are considerably less well understood. Previous work by our laboratory has demonstrated a beneficial effect of tamoxifen in the reduction of ischemic stroke damage in ovariectomized female rats. The present study utilized neuronal cell culture models to attempt to understand the mechanisms of tamoxifen-mediated neuroprotection. Neither physiologic doses of 17beta-E2 nor clinically therapeutic doses of tamoxifen directly protected GT1-7 neurons or purified cultures of rat cerebrocortical neurons from several forms of cell death. Reverse transcriptase polymerase chain reaction and Western blot analysis revealed that GT1-7 neurons possessed both estrogen receptor-alpha (ERalpha) and ERbeta mRNA and protein, whereas purified embryonic rat cortical neurons only expressed appreciable levels of ERalpha transcript and protein, with little to no expression of ERbeta. In contrast to the lack of protection in the purified neuronal cultures, both 17beta- E2 and tamoxifen significantly protected mixed glial/ neuronal cortical cultures from cell death, suggesting that glia may facilitate 17beta-E2-and tamoxifen-mediated neuroprotection. Furthermore, astrocyte-conditioned media and exogenous transforming growth factor-beta1, a documented astrocyte-derived cytokine, were shown to rescue purified cortical neurons from cell death. Together, these findings support a role for astrocytes in neuroprotection and raise the intriguing possibility that astrocytes may help mediate the neuroprotective effect of 17beta-E2 and tamoxifen.
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PMID:Neuroprotective effects of estrogen and tamoxifen in vitro: a facilitative role for glia? 1277 4

Many researchers have sought to study changes in gene expression in preclinical models of stroke. These range from in vitro models of ischemia, neuronal death, and regeneration to in vivo animal models aimed at replicating pathologies and regenerative processes typical of the clinical situation. In all such models, changes in gene expression occur, which may be assessed by measuring the abundance of the mRNA transcribed from particular genes of interest. The advent of real-time reverse-transcriptase polymerase chain reaction (RT-PCR) has vastly improved the sensitivity and accuracy of mRNA detection and is now the method of choice in many studies. Although this is a relatively simple and rapid technique, it has a number of pitfalls, especially in experimental design and data analysis. In this chapter we describe a detailed experimental protocol for real-time RT-PCR detection of mRNA transcripts, as used in the rat permanent middle cerebral artery occlusion model. We also discuss methods for analysis and interpretation of the resulting data.
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PMID:Quantitative analysis of gene transcription in stroke models using real-time RT-PCR. 1545 73

An important cellular event associated with reduced structural and functional recovery after stroke in aged animals is the early formation of a scar in the infarcted region that impairs neural recovery and repair. Despite the detrimental impact of infarct scar formation, the brain regions and cell types that supply the components of the scar are not well characterized. We hypothesized that premature cerebral scar formation in aged animals is associated with an altered cellular response to cerebral ischemia. Focal cerebral ischemia was produced by reversible occlusion of the right middle cerebral artery in 3 month- and 20 month-old male Sprague Dawley rats. After 3, 7, 14, and 28 days, brain tissue was subjected to real-time reverse-transcriptase-PCR (RT-PCR) and immunostaining for 1) a cellular proliferation marker (BrdU); 2) a neuroepithelial marker (nestin); 3) an astrocytic marker (glial fibrillary acidic protein [GFAP]); 4) a neuronal marker, doublecortin; and 5) a basal lamina marker (laminin), and analyzed using 3D-reconstruction of confocal images. In this model the infarct was localized primarily in the parietal cortex. By RT-PCR there was a robust increase in nestin mRNA transcripts shortly after stroke, and this increase was particularly intense in aged rats. Accordantly, we found in aged rats a rapid delimitation of the infarct area by nestin-positive cells and an early incorporation of these cells into the glial scar. The capillaries of the corpus callosum were the major source of proliferating, nestin-positive cells, many of which were also immunoreactive for doublecortin, although a smaller population of nestin cells were associated with the ventricular walls. Despite the proliferation of nestin cells, they did not make a significant contribution to neurogenesis in the infarcted cortex, possibly because the corpus callosum impedes the migration of subventricular zone-derived nestin-positive cells into the lesioned area. We conclude that: (i) the aged brain has the capability to mount a cytoproliferative response to injury, but the timing of the cellular and genetic reaction to cerebral insult is accelerated in aged animals; (ii) the proliferating cells contribute to the formation of the glial scar, but few of the cells appear to become neurons; and (iii) the vasculature plays a hitherto unrecognized role as a source of proliferating cells after stroke. Because capillary-derived cells help to form the glial scar, elucidating the molecular basis of this phenomenon and its acceleration in the aging brain could yield novel approaches to enhancing neurorestoration in the elderly.
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PMID:Accelerated delimitation of the infarct zone by capillary-derived nestin-positive cells in aged rats. 1647 21

Preclinical and clinical studies have demonstrated that a free radical scavenger edaravone has neuroprotective effects on ischemic stroke but the underlying mechanism is not fully understood. The aim of this research is to explore the effect of edaravone on the apoptotic process involving the Fas/FasL signaling pathway. Transient focal ischemia in rats was induced for 2 hours by middle cerebral artery occlusion (MCAO). After reperfusion rats were treated i.v. with either edaravone or physiological saline. The expression of Fas-associated death domain protein (FADD), death-associated protein (Daxx) and caspase-8 was examined by immunohistochemistry. The mRNA levels for FADD and Daxx by reverse-transcriptase PCR (RT-PCR) and apoptosis was assessed by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL). Neurological scores and infarction volumes were also evaluated. Edaravone significantly improved the neurological outcome (p<0.05) and reduced the total infarct volumes (p<0.05), compared with saline control. In addition, edaravone-treatment significantly reduced the number of TUNEL-positive cells (p<0.01), reduced expression levels of FADD, Daxx and caspase-8 immunoreactivity (p <0.05 approximately 0.01), and decreased mRNA levels of FADD and Daxx (p<0.05 approximately 0.01) within the peri-infarct area. We conclude that edaravone may protect ischemic neurons from apoptosis via suppressing the gene expression of the Fas/FasL signaling pathway.
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PMID:Edaravone neuroprotection effected by suppressing the gene expression of the Fas signal pathway following transient focal ischemia in rats. 1796 39

The distribution and density of pituitary adenylate cyclase-activating polypeptide (PACAP) binding sites have been investigated in the brain of the primates Jacchus callithrix (marmoset) and Macaca fascicularis (macaque) using [(125)I]-PACAP27 as a radioligand. PACAP binding sites were widely expressed in the brain of these two species with particularly high densities in the septum, hypothalamus and habenula. A moderate density of recognition sites was seen in all subdivisions of the cerebral cortex with a heterogenous distribution, the highest concentrations occurring in layers I and VI while the underlying white matter was almost devoid of binding sites. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis revealed intense expression of the mRNAs encoding the short and hop-1 variants of pituitary adenylate cyclase-activating polypeptide-specific receptor (PAC1-R) in the cortex of both marmoset and macaque, whereas vasoactive intestinal polypeptide/pituitary adenylate cyclase-activating polypeptide mutual receptor, subtype 1 (VPAC1-R) and vasoactive intestinal polypeptide/pituitary adenylate cyclase-activating polypeptide mutual receptor, subtype 2 (VPAC2-R) mRNAs were expressed at a much lower level. In situ hybridization histochemistry showed intense expression of PAC1-R and weak expression of VPAC1-R mRNAs in layer IV of the cerebral cortex. Incubation of cortical tissue slices with PACAP induced a dose-dependent stimulation of cyclic AMP formation, indicating that PACAP binding sites correspond to functional receptors. Moreover, treatment of primate cortical slices with 100 nM PACAP significantly reduced the activity of caspase-3, a key enzyme of the apoptotic cascade. The present results indicate that PACAP should exert the same neuroprotective effect in the brain of primates as in rodents and suggest that PAC1-R agonists may have a therapeutic value to prevent neuronal cell death after stroke or in specific neurodegenerative diseases.
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PMID:Distribution and functional characterization of pituitary adenylate cyclase-activating polypeptide receptors in the brain of non-human primates. 1923 5

Acidosis is a common feature of the human brain during ischemic stroke and is known to cause neuronal injury. However, the mechanism underlying acidosis-mediated injury of the human brain remains elusive. We show that a decrease in the extracellular pH evoked inward currents characteristic of acid-sensing ion channels (ASICs) and increased intracellular Ca(2+) in cultured human cortical neurons. Acid-sensing ion channels in human cortical neurons show electrophysiological and pharmacological properties distinct from those in neurons of the rodent brain. Reverse transcriptase-PCR and western blot detected a high level of the ASIC1a subunit with little or no expression of other ASIC subunits. Treatment of human cortical neurons with acidic solution induced substantial cell injury, which was attenuated by the ASIC1a blockade. Thus, functional homomeric ASIC1a channels are predominantly expressed in neurons from the human brain. Activation of these channels has an important role in acidosis-mediated injury of human brain neurons.
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PMID:Acid-sensing ion channels in acidosis-induced injury of human brain neurons. 2021 53

A better understanding of the underlying mechanisms of angiogenesis and vascular permeability is necessary for the development of therapeutic strategies for ischemic injury. The purpose of this study was to examine the spatial and temporal expression of Src and Src-suppressed C kinase substrate (SSeCKS) in brain after middle cerebral artery occlusion (MCAO) and elucidate the relationships among Src, SSeCKS, and the key angiogenic factors present after stroke. Rats were subjected to either MCAO or sham operation. Reverse transcriptase-polymerase chain reaction and Western blotting results revealed that Src gradually increased starting as early as 2 h after MCAO and remained high for 1 day. In contrast, SSeCKS decreased after MCAO. Src expression correlated positively with that of vascular endothelial growth factor and angiopoietin-2, and negatively with that of SSeCKS, angiopoietin-1, and zonula occludens-1. However, SSeCKS had the reverse correlations. Changes in the expression of these factors correlated with the progress of angiogenesis and cerebral edema. Dynamic temporal changes in Src and SSeCKS expression may modulate angiogenesis and cerebral edema formation after focal cerebral ischemia.
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PMID:Temporal profile of Src, SSeCKS, and angiogenic factors after focal cerebral ischemia: correlations with angiogenesis and cerebral edema. 2133 14

MicroRNAs (miRNAs) are present in serum and have the potential to serve as disease biomarkers. As such, it is important to explore the clinical value of miRNAs in serum as biomarkers for ischemic stroke (IS) and cast light on the pathogenesis of IS. In this study, we screened differentially expressed serum miRNAs from IS and normal people by miRNA microarray analysis, and validated the expression of candidate miRNAs using quantitative reverse-transcriptase polymerase chain reaction assays. Furthermore, we performed gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) pathway analyses to disclose functional enrichment of genes predicted to be regulated by the differentially expressed miRNAs. Notably, our results revealed that 115 miRNAs were differentially expressed in IS, among which miR-32-3p, miR-106-5p, and miR-532-5p were first found to be associated with IS. In addition, GO and KEGG pathway analyses showed that genes predicted to be regulated by differentially expressed miRNAs were significantly enriched in several related biological process and pathways, including axon guidance, glioma, MAPK signaling, mammalian target of rapamycin signaling, and ErbB-signaling pathway. In conclusion, we identified the changed expression pattern of miRNAs in IS. Serum miR-32-3p, miR-106-5p, miR-1246, and miR-532-5p may serve as potential diagnostic biomarkers for IS. Our results also demonstrate a novel role for miRNAs in the pathogenesis of IS.
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PMID:Identification of circulating microRNAs as potential biomarkers for detecting acute ischemic stroke. 2541 Mar 4

Diabetes is a major risk factor for stroke and is also associated with worsened outcomes following a stroke. Peroxiredoxin-2 exerts potent neuroprotective effects against oxidative stress. In the present study, we identified altered peroxiredoxin-2 expression in an ischemic stroke model under hyperglycemic conditions. Adult male rats were administrated streptozotocin (40 mg/kg) via intraperitoneal injection to induce diabetes. Middle cerebral artery occlusion (MCAO) was induced surgically 4 weeks after streptozotocin treatment and cerebral cortex tissues were isolated 24 hours after MCAO. Peroxiredoxin-2 expression was evaluated in the cerebral cortex of MCAO-operated animals using a proteomics approach, and was found to be decreased. In addition, the reduction in peroxiredoxin-2 levels was more severe in cerebral ischemia with diabetes compared to animals without diabetes. Reverse-transcriptase PCR and Western blot analyses confirmed the significantly reduced peroxiredoxin-2 expression in MCAO-operated animals under hyperglycemic conditions. It is an accepted fact that peroxiredoxin-2 has antioxidative activity against ischemic injury. Thus, the findings of this study suggest that a more severe reduction in peroxiredoxin-2 under hyperglycemic conditions leads to worsened brain damage during cerebral ischemia with diabetes.
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PMID:Hyperglycemia decreases preoxiredoxin-2 expression in a middle cerebral artery occlusion model. 2874 74


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