Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Kidney and liver are the major organs of erythropoietin (Epo) synthesis. However, Epo messenger RNA (mRNA) has been detected in several organs, such as brain, lung, and testis. Furthermore, functional Epo receptors have been demonstrated on different cell types, including rat Leydig cells. The aim of the study was to identify testicular cells expressing Epo mRNA and to quantitate its levels by competitive reverse transcriptase-polymerase chain reaction (RT-PCR). Besides whole testis, Epo transcripts were found in Sertoli and peritubular myoid cells, while no signal was detected in Leydig cells. Exposure of Sertoli cells to CoCl(2) led to an increase of Epo mRNA level. Semiquantitative competitive RT-PCR presented an increase in the level of Epo mRNA in Sertoli cells stimulated by follicle-stimulating hormone, while exposure of peritubular myoid cells cultures to testosterone reduced Epo mRNA expression. Due to the blood-testis barrier, basal expression of Epo suggests a not yet defined function of this hormone in testis.
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PMID:Erythropoietin expression in primary rat Sertoli and peritubular myoid cells. 1167 66

A 14-year-old mixed-breed dog was examined because of severe absolute erythrocytosis (PCV, 70%). Plasma erythropoietin (EPO) concentration was consistently high, even though results of arterial blood gas analyses were normal. Radiography, ultrasonography, urinalysis, and serum biochemical analyses did not reveal any cardiac, pulmonary, or renal abnormalities that could cause the erythrocytosis, and erythrocytosis secondary to inappropriate EPO secretion was diagnosed. The PCV was maintained at approximately 60% by means of periodic phlebotomy, and the dog died of acute renal failure 2 years later. At necropsy, a cecal leiomyosarcoma was identified. Immunohistochemical staining of sections of the tumor revealed intracellular vacuoles containing EPO, and EPO mRNA was detected in the tumor by use of a reverse transcriptase-polymerase chain reaction assay These results suggested that ectopic production of EPO by a cecal leiomyosarcoma was the cause of erythrocytosis in this dog.
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PMID:Secondary erythrocytosis associated with high plasma erythropoietin concentrations in a dog with cecal leiomyosarcoma. 1186 Feb 44

Erythropoietin (Epo) modulates calcium influx through voltage-independent calcium-permeable channel(s). Here, we characterized the expression of transient receptor potential channels (TRPCs) in primary erythroid cells and examined their regulation. Erythroblasts were isolated from the spleens of phenylhydrazine-treated mice, and Epo stimulation resulted in a significant and dose-dependent increase in [Ca](i). Among the classical TRPC channels, expression of three N-terminal splice variants of TRPC2 (clones 14, 17, and alpha) and of TRPC6 were demonstrated in these erythroblasts by both reverse transcriptase-PCR and Western blotting. Confocal microscopy confirmed localization to the plasma membrane. To determine the function of individual TRPC channels in erythropoietin modulation of calcium influx, digital video imaging was used to measure calcium influx through these TRPCs in a Chinese hamster ovary (CHO) cell model. Single CHO-S cells, expressing transfected Epo-R, were identified by detection of green fluorescent protein. Cells that express transfected TRPCs were identified by detection of blue fluorescent protein. [Ca](i) was monitored with Fura Red. Epo stimulation of CHO-S cells transfected with single TRPC2 isoforms (clone 14, 17, or alpha) and Epo-R resulted in a significant increase in [Ca](i). This was not observed in cells transfected with Epo-R and TRPC6. In addition, coexpression of TRPC6 with TRPC2 and Epo-R inhibited the increase in [Ca](i) observed after Epo stimulation. Immunoprecipitation experiments demonstrated that TRPC2 associates with TRPC6, indicating that these TRPCs can form multimeric channels. These data demonstrate that specific TRPCs are expressed in primary erythroid cells and that two of these channels, TRPC2 and TRPC6, can interact to modulate calcium influx stimulated by erythropoietin.
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PMID:Interaction of TRPC2 and TRPC6 in erythropoietin modulation of calcium influx. 1469 31

Although information about the development of primitive and definitive hematopoiesis has been elucidated in murine embryos and embryonic stem (ES) cells, there have been few in vitro studies of these processes in primates. In this study, we investigated hematopoietic differentiation from cynomolgus monkey ES cells grown on OP9, a stromal cell line deficient in macrophage colony-stimulating factor. Primitive erythrocytes (EryP) and definitive erythrocytes (EryD) developed sequentially from ES cells in the culture system; this was confirmed by immunostaining and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of embryonic, fetal and adult globin genes. EryP were detected on day 8 without exogenous erythropoietin (EPO), whereas EryD appeared on day 16 and had an indispensable requirement for exogenous EPO. RT-PCR analysis of the cultures revealed a sequential expression of genes associated with primitive and definitive hematopoietic development that was equivalent to that seen during primate ontogeny in vivo. Vascular endothelial growth factor (VEGF) increased, in a dose-dependent manner, not only the number of floating hematopoietic cells, but also the number of adherent hematopoietic cell clusters containing CD34-positive immature progenitors. In colony assays, exogenous VEGF also had a dose-dependent stimulatory effect on the generation of primitive erythroid colonies. More efficient primitive and definitive erythropoiesis was induced by re-plating sorted CD34-positive cells. Thus, this system reproduces early hematopoietic development in vitro and can serve as a model for analyzing the mechanisms of hematopoietic development in primates.
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PMID:Development of primitive and definitive hematopoiesis from nonhuman primate embryonic stem cells in vitro. 1508 70

Kidney-targeted gene transfer is expected to revolutionize the treatment of renal diseases. Recently, we demonstrated that naked plasmid deoxyribonucleic acid (DNA) can be transferred into renal interstitial fibroblasts near the peritubular capillaries (PTCs) in normal rats, by retrograde injection into the renal vein with the renal vein and artery clamped. The PTC network is a main target of kidney transplant rejection and of progressive tubulointerstitial fibrosis, which typifies all progressive renal diseases. We retrogradely injected a lacZ expression plasmid in Ringer's solution into the renal vein of rats using a 24-gage catheter. We detected lacZ expression exclusively in the interstitial fibroblasts near the PTCs of the kidney by immunoelectron microscopy. Nephrotoxicity from the gene transfer was not apparent. We then used a rat erythropoietin (Epo) expression plasmid vector pCAGGS-Epo in a reporter assay. We obtained maximal Epo expression when the DNA solution was injected within 5 s in a volume of 1.0 mL. We detected transgene-derived Epo messenger ribonucleic acid by reverse transcriptase polymerase chain reaction only in the kidneys receiving pCAGGS-Epo. In this article, protocols for naked plasmid DNA transfer into rat kidney using this hydrodynamics-based transfection method and the immunoelectron microscopic technique to determine the lacZ gene transfer site are described in detail.
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PMID:Rat kidney-targeted naked plasmid DNA transfer by retrograde injection into the renal vein. 1512 45

To examine the changes in erythropoietin (Epo) protein and its mRNA expression in rat brain subjected to focal ischemia and possible mechanism of the preconditioning of mitochondrial toxin 3-nitropropionic acid (3-NPA), rats were administrated either vehicle or 3-NPA at a dose of 20 mg/kg, intraperitoneally (ip), 3 days prior to a 2-h middle cerebral artery occlusion followed by 24-h reperfusion. Infarct volumes were measured by using 2, 3, 5 triphenylte trazolinm chloride (TTC) staining, and Epo protein and its mRNA levels were assessed by immunohistochemistry and reverse transcriptase polymerase chain reaction (RT-PCR), respectively. Our results showed that after reperfusion, Epo was found to be expressed extensively in the rat brain. It was most apparent in the basal nuclei and hippocampus, and was, to some extent, present in cortex. Preconditioning with 3-NPA caused a reduction in infarct volume. The expression of both Epo protein and mRNA increased significantly in the different brain areas in the 3-NPA pretreated group as compared with the non-pretreated ischemia model group. These results suggested that preconditioning with low dose 3-NPA could induce ischemic tolerance and neuro-protective effects by increasing the Epo expression in the ischemic and ischemia-related areas.
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PMID:Cerebral ischemic tolerance induced by 3-nitropropionic acid is associated with increased expression of erythropoietin in rats. 1712 Jul 43

The neuroprotective effects of exogenous erythropoietin (EPO) in animals and humans after brain injury may be afforded, in part, by the influence of EPO on cerebral arteries. We tested (1) if EPO itself is vasoactive and (2) if EPO enhances endothelium-mediated dilations, specifically those mediated by endothelium-derived hyperpolarizing factor (EDHF). Immunoblotting and reverse transcriptase-polymerase chain reaction (RT-PCR) were used to detect EPO receptor. Rat middle cerebral arteries (MCAs) were isolated, pressurized, and perfused in vitro. EPO was directly applied to MCAs to test its vasoactivity. Endothelium-mediated dilations were elicited by UTP, whereas EDHF-mediated dilations were elicited by UTP after inhibition of endothelial nitric oxide synthase and cyclooxygenase. mRNA and protein for EPO receptor was found in rat MCA. Abluminal application of 0.001-10 U/mL EPO, which is selective for vascular smooth muscle, did not alter vessel diameter. In contrast, luminal application of EPO, which is selective for endothelium, resulted in concentration-dependent dilations of up to 39 +/- 16% at 10 U/mL (p = 0.0018), though responses were variable. A single dose of EPO (1,000 U/kg) administered to rats 24 h prior to examining vascular function potentiated dilations to UTP 2.6-fold (p < 0.0001). EDHF-mediated dilations were potentiated 2.1-fold following in vivo EPO treatment (p = 0.0034). This study demonstrates that EPO can directly dilate rat MCAs via the endothelium, though not all vessels are responsive. Additionally, pre-treatment with EPO for 24 h in vivo potentiates endothelium-mediated dilations, specifically those mediated by EDHF. Thus, enhanced endothelium-mediated dilations may partially underlie the neuroprotective effects of EPO after brain injury.
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PMID:Erythropoietin potentiates EDHF-mediated dilations in rat middle cerebral arteries. 1835 39

Systemic administration of erythropoietin (Epo) protects the myocardium from an ischemic insult and promotes beneficial remodeling. We hypothesized that intracardiac injection of Epo may exhibit cardioprotective potential with reduced systemic toxicity. Following myocardial infarction (MI), Epo was injected directly into the border of the infarction. Six weeks after an MI, we evaluated infarction size, angiogenesis, and pathologic effects of the treatment. Myocardial performance was assessed with a Forced Swim Test adapted to the study. Anti-inflammatory and cellular proliferative effects of Epo were analyzed by measuring expression of integrin-beta and CdK4 by reverse transcriptase-polymerase chain reaction (RT-PCR). The findings indicated improved cardiac status with direct Epo administration. Exercise capacity detected by the Forced Swim Test was significantly increased. There was radical reduction of absolute infarction size, ventricular dilatation, and hypertrophy in the Epo group. Integrin-beta was down-regulated and CdK4 expression was increased significantly with Epo. In conclusion, the study demonstrated that intramyocardial Epo injection, following MI, reduced inflammation, enhanced angiogenesis and proliferation, improved myocardial functions, and did not lead to intramural thrombus formation.
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PMID:Intracardiac erythropoietin injection reveals antiinflammatory potential and improved cardiac functions detected by Forced Swim Test. 1855 90

Increased risk of cardiovascular disease in end-stage renal disease (ESRD) has been explained by accelerated atherosclerosis and impaired angiogenesis, in which endothelial progenitor cells (EPC) may play key roles. Circulating cells with endothelial progenitor phenotype have not been evaluated in children with ESRD. Using a quantitative reverse transcriptase polymerase chain reaction (RT-PCR) approach, we measured endothelial-specific and progenitor-associated genes VE-cadherin (VE-C), CD146, CD31, tyrosine-protein kinase receptor (Tie-2), Flk1, CD133, and growth factors promoting EPC function, vascular endothelial growth factor (VEGF), erythropoietin (EPO), and stromal cell-derived factor-1 (SDF-1) in the blood of pediatric patients undergoing hemodialysis and after transplantation. Patients' metabolic parameters were correlated with EPC marker gene levels. Compared with controls, circulating VE-cadherin, CD146, Flk1, VEGF, and EPO RNA levels were decreased in ESRD and normalized in transplanted patients. Levels of VE-cadherin, which were the most significantly reduced in ESRD (p = 0.001) inversely correlated in all of the patient population with serum urea and creatinine concentration, whereas among the ESRD group showed an inverse correlation with diastolic blood pressure (BP), interventricular septum thickness (IVST), and left ventricular mass index. Pediatric ESRD patients may have lower angiogenic potential and increased cardiovascular morbidity, because of decreased expression of circulating endothelial cell specific transcripts. Prospective studies are required to link this expression pattern and its restoration in transplanted patients to cardiovascular outcome.
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PMID:Molecular evaluation of circulating endothelial progenitor cells in children undergoing hemodialysis and after kidney transplantation. 1885 88

This study focuses on the prevalence of hepatitis G virus (GBV-C/HGV) in hemodialysis patients and blood donors in Denizli (located at Aegean region of Turkey). A total of 100 patients (mean age: 56.8 +/- 13.3 years; 46 female) receiving hemodialysis and 100 blood donors (mean age: 31.3 +/- 8.1 years; 8 female) were included in the study. The presence of GBV-C/HGV RNA was determined in all patients by reverse transcriptase-PCR and the presence of GBV-C/HGV anti-E2 antibodies was determined by a commercial enzyme immunoassay (Diagnostic Automation, INC). Viral RNA positivity was determined in 14 (14%) of the hemodialysis patients and 2 (2%) of the blood donors, the difference being statistically significant (p < 0.05). GBV-C/HGV anti-E2 antibodies were detected in 1 (1%) of the hemodialysis patients and 3 (3%) of the blood donors. Anti-E2 positive patient also revealed positive result for viral RNA. There was no statistically significant difference between the two groups in terms of anti-E2 positivity. The prevalence of GBV-C/HGV was 14% in hemodialysis patients and 5% in blood donors (p < 0.05). There was no significant difference in terms of duration of hemodialysis, serum ALT levels, age or gender between GBV-C/HGV positive and negative hemodialysis patients. In conclusion, since hemodialysis patients are at an increased risk of parenteral transmission, they have significantly higher GBV-C/HGV viremia rates and prevalence when compared to blood donors. However, the prevalence of GBV-C/HGV and coexistence between GBV-C/HGV and hepatitis C virus have been decreasing in our region owing to increased hygienic precautions in hemodialysis units, avoidance of unnecessary blood transfusions and more widespread use of erythropoietin.
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PMID:[Investigation of hepatitis G virus prevalence in hemodialysis patients and blood donors in Denizli, Turkey]. 1914 83


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