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Sample records for active erythropoietin receptor

  1. Identification of tyrosine residues within the intracellular domain of the erythropoietin receptor crucial for STAT5 activation.

    Gobert, S.; Chretien, S; Gouilleux, F; Muller, O.; Pallard, C; Dusanter-Fourt, I; Groner, B; Lacombe, C.; Gisselbrecht, S; Mayeux, P

    1996-01-01

    FDCP-1 cells are hematopoietic progenitor cells which require interleukin-3 for survival and proliferation. FDCP-1 cells stably transfected with the murine erythropoietin receptor cDNA survive and proliferate in the presence of erythropoietin. Erythropoietin induces the activation of the short forms (80 kDa) of STAT5 in the cells. Erythropoietin-induced activation of STAT5 was strongly reduced in cells expressing mutated variants of the erythropoietin receptors in which tyrosine residues in t...

  2. Biotinylated recombinant human erythropoietins: Bioactivity and utility as receptor ligand

    Wojchowski, D.M.; Caslake, L. (Pennsylvania State Univ., University Park (USA))

    1989-08-15

    Recombinant human erythropoietin labeled covalently with biotin at sialic acid moieties has been prepared, and has been shown to possess high biological activity plus utility as a receptor ligand. Initially, the effects on biological activity of covalently attaching biotin to erythropoietin alternatively at carboxylate, amino, or sialic acid groups were compared. Biotinylation of erythropoietin at carboxylate groups using biotin-amidocaproyl hydrazide plus 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide led to substantial biological inactivation, although biotinylated molecules retained detectable activity when prepared at low stoichiometries. Biotinylation at amino groups using sulfosuccinimidyl 6-(biotinamido) hexanoate resulted in a high level of biological inactivation with little, if any, retention of biological activity, regardless of labeling stoichiometries. Biotinylation at sialic acid moieties using periodate and biotinamidocaproyl hydrazide proceeded efficiently (greater than 95% and 80% labeling efficiencies for human urinary and recombinant erythropoietin, respectively) and yielded stably biotinylated erythropoietin molecules possessing comparably high biological activity (ie, 45% of the activity of unmodified hormone). Utility of recombinant biotin-(sialyl)-erythropoietin (in combination with 125I-streptavidin) in the assay of cell surface receptors was demonstrated using two distinct murine erythroleukemia cell lines, Friend 745 and Rauscher Red 1. The densities and affinities of specific hormone binding sites were 116 +/- 4 sites, 3.3 +/- 0.4 nmol/L kd and 164 +/- 5 sites, 2.7 +/- 0.4 nmol/L kd, respectively. It is predicted that the present development of biotin-(sialyl)-erythropoietin as a chemically and biologically stable, bioactive ligand will assist in advancing an understanding of the regulated expression and physicochemistry of the human and murine erythropoietin receptors.

  3. Soluble Erythropoietin Receptor Contributes to Erythropoietin Resistance in End-Stage Renal Disease

    Khankin, Eliyahu V.; Walter P Mutter; Hector Tamez; Hai-Tao Yuan; S Ananth Karumanchi; Ravi Thadhani

    2010-01-01

    BACKGROUND: Erythropoietin is a growth factor commonly used to manage anemia in patients with chronic kidney disease. A significant clinical challenge is relative resistance to erythropoietin, which leads to use of successively higher erythropoietin doses, failure to achieve target hemoglobin levels, and increased risk of adverse outcomes. Erythropoietin acts through the erythropoietin receptor (EpoR) present in erythroblasts. Alternative mRNA splicing produces a soluble form of EpoR (sEpoR) ...

  4. A dimeric peptide with erythropoiesis-stimulating activity uniquely affects erythropoietin receptor ligation and cell surface expression.

    Verma, Rakesh; Green, Jennifer M; Schatz, Peter J; Wojchowski, Don M

    2016-08-01

    Erythropoiesis-stimulating agents (ESAs) that exert long-acting antianemia effects have been developed recently, but their mechanisms are poorly understood. Analyses reveal unique erythropoietin receptor (EPOR)-binding properties for one such ESA, the synthetic EPOR agonist peginesatide. Compared with recombinant human EPO and darbepoietin, peginesatide exhibited a slow on rate, but sustained EPOR residency and resistant displacement. In EPO-dependent human erythroid progenitor UT7epo cells, culture in peginesatide unexpectedly upmodulated endogenous cell surface EPOR levels with parallel increases in full-length EPOR-68K levels. These unique properties are suggested to contribute to the durable activity of this (and perhaps additional) dimeric peptide hematopoietic growth factor receptor agonist. PMID:27174804

  5. Efficacy,safety and tolerance of continuous erythropoietin receptor activator intravenous administration on anemia correction in dialysis patients with chronic renal anemia

    钱家麒

    2013-01-01

    Objective To evaluate the efficacy,safety and toler-ance of continuous erythropoietin receptor activator(CE-RA) once every 2 weeks intravenous injection on anemia correction in dialysis patients compared to Epoetin-β(EPO-β) administration. Methods An open label,

  6. Once-Monthly Continuous Erythropoietin Receptor Activator (C.E.R.A.) in Patients with Hemodialysis-Dependent Chronic Kidney Disease: Pooled Data from Phase III Trials

    Locatelli, Francesco; Choukroun, Gabriel; Truman, Matt; Wiggenhauser, Alfons; Fliser, Danilo

    2016-01-01

    Introduction Erythropoiesis-stimulating agents and iron are commonly used in patients with chronic kidney disease with the aim of correcting anemia and maintaining stable hemoglobin levels. We analyzed pooled data from 13 studies with similar designs included in the Umbrella Continuous Erythropoietin Receptor Activator (C.E.R.A.) program to investigate the effects of continuous erythropoiesis receptor activator in clinically relevant subgroups of patients with chronic kidney disease and to de...

  7. Erythropoietin receptor signaling is membrane raft dependent.

    Kathy L McGraw

    Full Text Available Upon erythropoietin (Epo engagement, Epo-receptor (R homodimerizes to activate JAK2 and Lyn, which phosphorylate STAT5. Although recent investigations have identified key negative regulators of Epo-R signaling, little is known about the role of membrane localization in controlling receptor signal fidelity. Here we show a critical role for membrane raft (MR microdomains in creation of discrete signaling platforms essential for Epo-R signaling. Treatment of UT7 cells with Epo induced MR assembly and coalescence. Confocal microscopy showed that raft aggregates significantly increased after Epo stimulation (mean, 4.3±1.4(SE vs. 25.6±3.2 aggregates/cell; p≤0.001, accompanied by a >3-fold increase in cluster size (p≤0.001. Raft fraction immunoblotting showed Epo-R translocation to MR after Epo stimulation and was confirmed by fluorescence microscopy in Epo stimulated UT7 cells and primary erythroid bursts. Receptor recruitment into MR was accompanied by incorporation of JAK2, Lyn, and STAT5 and their activated forms. Raft disruption by cholesterol depletion extinguished Epo induced Jak2, STAT5, Akt and MAPK phosphorylation in UT7 cells and erythroid progenitors. Furthermore, inhibition of the Rho GTPases Rac1 or RhoA blocked receptor recruitment into raft fractions, indicating a role for these GTPases in receptor trafficking. These data establish a critical role for MR in recruitment and assembly of Epo-R and signal intermediates into discrete membrane signaling units.

  8. Activation of erythropoietin receptors by Friend viral gp55 and by erythropoietin and down-modulation by the murine Fv-2r resistance gene

    The leukemogenic membrane glycoprotein (gp55) encoded by Friend spleen focus-forming virus appears to bind to erythropoietin receptors (EpoR) to stimulate erythroblastosis. To directly compare the effects of gp55 with erythropoietin (Epo), the authors produced retrovirions that encode either gp55, Epo, or EpoR. After infection with EpoR virus, interleukin 3-dependent DA-3 cells bound 125I-labeled Epo and grew without interleukin 3 in the presence of Epo. These latter cells, but not parental DA-3 cells, became factor-independent after superinfection either with Epo virus or with Friend spleen focus-forming virus. In addition, Epo virus caused a disease in mice that mimicked Friend erythroleukemia. Although Fv-2r homozygotes are susceptible to all other retroviral diseases, they are resistant to both Epo viral and Friend viral erythroleukemia. These results indicate that both gp55 and Epo stimulate EpoR and that the Fv-2 gene encodes a protein that controls response to these ligands. However, the Fv-2 protein is not EpoR because the corresponding genes map to opposite ends of mouse chromosome 9. These results have important implications for understanding signal transduction by EpoR and the role of host genetic variation in controlling susceptibility to an oncogenic protein

  9. Dose equivalence between continuous erythropoietin receptor activator (CERA), Darbepoetin and Epoetin in patients with advanced chronic kidney disease

    Vega, A; Abad, S; Verdalles, U; Aragoncillo, I; Velazquez, K; Quiroga, B; Escudero, V; López-Gómez, JM

    2014-01-01

    Background: Anemia is a prevalent situation in patients with chronic kidney disease (CKD) and can be well managed with erythropoiesis-stimulating agents (ESAs). Continuous erythropoietin receptor activator (CERA) has a long half-life that allows to be administered once monthly. The lowest recommended dose for patients with non dialysis CKD is 120 μg per month. The objectives were to assess the efficacy of subcutaneous monthly dosing of CERA in CKD stages 4 and 5 not on dialysis, and to determine the equivalent dose to epoetin β and darbepoetin α. Methods: This is a cohort study. A 30-patient group that ESAs was changed to CERA (μg/month) was used as treatment group. We used the following clinically-based equivalent dosing: epoetin β (IU/week) and darbepoetin α (μg/week): 3000/15= 50; 4000/20=75; 6000/30=100; 8000/40=150. Another group of 30 patients with similar characteristics was used as control group and received the same epoetin β and darbepoetin α doses. Results: The mean CERA initial dose and at 6 months was 81.9 ± 35.2 and 82.0 ± 37.82 μg/month (p=0.37). The mean erythropoietin resistance index (ERI) and hemoglobin at baseline and at 6 months in the CERA group and in the control group were not statistically significant. Conclusion: Monthly dosing treatment with CERA is safe and effective. A dose of 75-100 μg/month is enough to maintain stable levels of hemoglobin. Hippokratia 2014; 18 (4): 315-318. PMID:26052197

  10. AMPK is Involved in Mediation of Erythropoietin Influence on Metabolic Activity and Reactive Oxygen Species Production in White Adipocytes

    Wang, Li; Di, Lijun; Noguchi, Constance Tom

    2014-01-01

    Erythropoietin, discovered for its indispensable role during erythropoiesis, has been used in the therapy for selected red blood cell disorders in erythropoietin-deficient patients. The biological activities of erythropoietin have been found to extend to non-erythroid tissues due to the expression of erythropoietin receptor. We previously demonstrated that erythropoietin promotes metabolic activity and white adipocytes browning to increase mitochondrial function and energy expenditure via per...

  11. Erythropoietin and erythropoietin receptor expression in the guinea pig inner ear

    Cayé-Thomasen, Per; Wagner, Niels; Lidegaard Frederiksen, Birgitte;

    2005-01-01

    The erythropoietin receptor (EPOR) is expressed in the brain and erythropoietin (EPO) has been shown to have neurotrophic and neuroprotective functions in the central nervous system and in the retina. These findings may be applied to the inner ear, pending EPO receptor presence. Accordingly, this...

  12. Expression of constitutively active erythropoietin receptor in pyramidal neurons of cortex and hippocampus boosts higher cognitive functions in mice

    Hassouna Imam

    2011-04-01

    Full Text Available Abstract Background Erythropoietin (EPO and its receptor (EPOR are expressed in the developing brain and their transcription is upregulated in adult neurons and glia upon injury or neurodegeneration. We have shown neuroprotective effects and improved cognition in patients with neuropsychiatric diseases treated with EPO. However, the critical EPO targets in brain are unknown, and separation of direct and indirect effects has remained difficult, given the role of EPO in hematopoiesis and brain oxygen supply. Results Here we demonstrate that mice with transgenic expression of a constitutively active EPOR isoform (cEPOR in pyramidal neurons of cortex and hippocampus exhibit enhancement of spatial learning, cognitive flexibility, social memory, and attentional capacities, accompanied by increased impulsivity. Superior cognitive performance is associated with augmented long-term potentiation of cEPOR expressing neurons in hippocampal slices. Conclusions Active EPOR stimulates neuronal plasticity independent of any hematopoietic effects and in addition to its neuroprotective actions. This property of EPOR signaling should be exploited for defining novel strategies to therapeutically enhance cognitive performance in disease conditions.

  13. Evaluation of functional erythropoietin receptor status in skeletal muscle in vivo

    Christensen, Britt; Lundby, Carsten; Jessen, Niels;

    2012-01-01

    myosin light chain 3 and one of desmin/actin were decreased, while three isoforms of creatine kinase and two of glyceraldehyd-3-phosphate dehydrogenase were increased. Conclusions/Significance: Acute exposure to recombinant human erythropoietin is not associated by detectable activation of the Epo-R or......Background: Erythropoietin receptors have been identified in human skeletal muscle tissue, but downstream signal transduction has not been investigated. We therefore studied in vivo effects of systemic erythropoietin exposure in human skeletal muscle. Methodology/Principal Findings: The protocols...... involved 1) acute effects of a single bolus injection of erythropoietin followed by consecutive muscle biopsies for 1-10 hours, and 2) a separate study with prolonged administration for 16 days with biopsies obtained before and after. The presence of erythropoietin receptors in muscle tissue as well as...

  14. Functional erythropoietin receptors on human tumor cells

    Erythropoietin (EPO) is the principal regulator of red blood cell survival, growth and maturation and has achieved great clinical utility for the correction of anemia associated with renal failure, cancer and chemotherapy, and stem cell transplantation. EPO increasingly is being recognized as a pleiotrophic growth factor, having actions on nonhematopoietic cells as well. Both EPO and erythropoietin receptor (EPO-R) expression have been associated with cells of the endothelium, retina, central nervous system, gastrointestinal tract and female reproductive system. The role of EPO in these nonhematopoietic sites is not thoroughly understood and in some instances may be site-specific. Promotion of angiogenesis and blood vessel integrity, increased cell proliferation, prevention of apoptosis, and protection against ischemic damage in the presence of hypoxia have all been described as possible functions of EPO in one or more of these cell types. On the other hand, EPO-R also have been identified on a variety of tumor cells (while in some cases not on the adjacent normal tissue), and several reports have suggested a role for EPO in the direct stimulation of cancer cell growth in vivo and in vitro. Among those tumor cells on which we and others have identified functional EPO-R are breast and ovarian cancer cells. Additionally, the work presented here describes the first evidence that transformed prostate epithelial cells, prostate cancer cell lines, and both normal and cancerous prostate tissue express EPO-R. All of the EPO-R bearing prostate cell lines tested underwent a significant dose-dependent proliferative response to EPO, and EPO triggered intracellular signaling in the cells as evidenced by protein phosphorylation. The results implicate EPO in the biology of both normal and malignant prostate cells and suggest the need for careful evaluation of the use of recombinant EPO as a therapeutic agent in prostate cancer

  15. Development of Radiolabeled Recombinant Erythropoietin for Receptor Studies

    The study of human erythropoietin receptor is of great importance in evolution, carcinogenesis as well as endocrine research. In this study the production and quality control of human recombinant erythropoietin (EPO) has been reported. EPO was successively labeled with [67Ga]-gallium chloride after conjugation with freshly prepared cyclic DTPA-dianhydride (ccDTPA). The best results of the conjugation were obtained by the addition of 0.5 ml of a EPO pharmaceutical solution (in phosphate buffer, pH=8) to a glass tube pre-coated with DTPA-dianhydride (0.01 mg) at 25degreeC with continuous mild stirring for 30 min followed by HPLC/RTLC control and biological biodistribution in normal rats. Under optimized conditions, radio-thin layer chromatography (RTLC), instant thin layer chromatography (ITLC) and high performance liquid chromatography (HPLC) showed overall radiochemical purity of higher than 96%(specific activity=300-500 MBq/mg, labeling efficiency 77%). Preliminary in vivo studies in normal rat specimen demonstrated a high liver, lung spleen, kidney as well as long bones uptake of the tracer; the fact which is consistent with the reported EPO receptor sites. This tracer can be used in nuclear medicine and biological studies for evaluation of EPO in vitro and/or in vivo.

  16. Phagocyte respiratory burst activates macrophage erythropoietin signalling to promote acute inflammation resolution.

    Luo, Bangwei; Wang, Jinsong; Liu, Zongwei; Shen, Zigang; Shi, Rongchen; Liu, Yu-Qi; Liu, Yu; Jiang, Man; Wu, Yuzhang; Zhang, Zhiren

    2016-01-01

    Inflammation resolution is an active process, the failure of which causes uncontrolled inflammation which underlies many chronic diseases. Therefore, endogenous pathways that regulate inflammation resolution are fundamental and of wide interest. Here, we demonstrate that phagocyte respiratory burst-induced hypoxia activates macrophage erythropoietin signalling to promote acute inflammation resolution. This signalling is activated following acute but not chronic inflammation. Pharmacological or genetical inhibition of the respiratory burst suppresses hypoxia and macrophage erythropoietin signalling. Macrophage-specific erythropoietin receptor-deficient mice and chronic granulomatous disease (CGD) mice, which lack the capacity for respiratory burst, display impaired inflammation resolution, and exogenous erythropoietin enhances this resolution in WT and CGD mice. Mechanistically, erythropoietin increases macrophage engulfment of apoptotic neutrophils via PPARγ, promotes macrophage removal of debris and enhances macrophage migration to draining lymph nodes. Together, our results provide evidences of an endogenous pathway that regulates inflammation resolution, with important implications for treating inflammatory conditions. PMID:27397585

  17. Identification of the receptor for erythropoietin on human and murine erythroleukemia cells and modulation by phorbol ester and dimethyl sulfoxide.

    Broudy, V C; Lin, N.; Egrie, J; de Haën, C; Weiss, T.; Papayannopoulou, T; Adamson, J W

    1988-01-01

    Erythropoietin, a glycoprotein that regulates erythropoiesis, initiates its biological effects by binding to a cell-surface receptor. Little is known about the structure of the erythropoietin receptor and the events that follow binding of erythropoietin to its receptor, in part because of the difficulty of obtaining sufficient quantities of cells that express the erythropoietin receptor. We used both iodinated and metabolically labeled erythropoietin to characterize the receptor on a variety ...

  18. The role of erythropoietin and erythropoietin receptor in malignant laryngeal tumors.

    Vukelic, Jelena; Dobrila-Dintinjana, Renata; Jonjic, Nives; Dekanic, Andrea; Ilijic, Vjekoslav

    2013-12-01

    Erythropoietin (Epo) is a glycoprotein hormone responsible for erythropoiesis. Its effect is realized by binding erythropoietin receptor (EpoR) expressed on erythroid progenitor cells. Hypoxia is the main stimulus for the secretion of erythropoietin. Anemia is an independent negative prognostic factor for survival in patients with malignant diseases. Synthetic forms of erythropoietin are used in clinical oncology practice to increase the level of hemoglobin. As well as endogenous they can bind to EpoR. Considering the fact that most effects of synthetic Epo are negative, the role of endogenous Epo/EpoR has become an extremely important issue. The authors do not agree on most items related to the effects of exogenous Epo and EpoR in patients with head and neck carcinomas. We are investigating the expression of Epo/EpoR in the tissue of malignant laryngeal carcinoma. Our hypothesis is that less differentiated laryngeal carcinomas will have a higher level of endogenous Epo/EpoR expression. Therefore, in patients with positive Epo/EpoR we expect shorter survival and poorer locoregional disease control. We anticipate that our hypothesis may help to provide the role of endogenous Epo/EpoR in patients with malignant tumors of the larynx. If the assumptions of this study are confirmed, the patients with laryngeal carcinomas whose tumor cells express Epo/EpoR should not be considered for the treatment of anemia with recombinant erythropoietin in any case. We also point out that our research will expand the knowledge of the biology of laryngeal tumor cells and that the results could be utilized as basic knowledge in development of future therapeutic strategies. PMID:24134826

  19. Erythropoietin.

    Bunn, H Franklin

    2013-03-01

    During the past century, few proteins have matched erythropoietin (Epo) in capturing the imagination of physiologists, molecular biologists, and, more recently, physicians and patients. Its appeal rests on its commanding role as the premier erythroid cytokine, the elegant mechanism underlying the regulation of its gene, and its remarkable impact as a therapeutic agent, arguably the most successful drug spawned by the revolution in recombinant DNA technology. This concise review will begin with a synopsis of the colorful history of this protein, culminating in its purification and molecular cloning. It then covers in more detail the contemporary understanding of Epo's physiology as well as its structure and interaction with its receptor. A major part of this article focuses on the regulation of the Epo gene and the discovery of HIF, a transcription factor that plays a cardinal role in molecular adaptation to hypoxia. In the concluding section, a synopsis of Epo's role in disorders of red blood cell production will be followed by an assessment of the remarkable impact of Epo therapy in the treatment of anemias, as well as concerns that provide a strong impetus for the development of even safer and more effective treatment. PMID:23457296

  20. Erythropoietin

    Miskowiak, Kamilla W; Vinberg, Maj; Harmer, Catherine J;

    2012-01-01

    Current pharmacological treatments for depression have a significant treatment-onset-response delay, an insufficient efficacy for many patients and fail to reverse cognitive dysfunction. Erythropoietin (EPO) has neuroprotective and neurotrophic actions and improves cognitive function in animal...

  1. Erythropoietin regulates Treg cells in asthma through TGFβ receptor signaling.

    Wan, Guoshi; Wei, Bing

    2015-01-01

    Asthma is a chronic inflammatory disorder of the airways, the development of which is suppressed by regulatory T cells (Treg). Erythropoietin (EPO) is originally defined as a hematopoietic growth factor. Recently, the anti-inflammatory effects of EPO in asthma have been acknowledged. However, the underlying mechanisms remain ill-defined. Here, we showed that EPO treatment significantly reduced the severity of an ovalbumin (OVA)-induced asthma in mice, seemingly through promoting Foxp3-mediated activation of Treg cells in OVA-treated mouse lung. The activation of Treg cells resulted from increases in transforming growth factor β1 (TGFβ1), which were mainly produced by M2 macrophages (M2M). In vitro, Co-culture with M2M increased Foxp3 levels in Treg cells and the Treg cell number, in a TGFβ receptor signaling dependent manner. Moreover, elimination of macrophages abolished the therapeutic effects of EPO in vivo. Together, our data suggest that EPO may increase M2M, which activate Treg cells through TGFβ receptor signaling to mitigate the severity of asthma. PMID:26807178

  2. Effects of erythropoietin and its receptor on nervous system

    Ping Wang; Wei Zhou

    2006-01-01

    OBJECTIVE: To investigate the effects of erythropoietin (EPO) and its receptor (EPOR) on nervous system, and its possible mechanism.DATA SOURCES: By inputting the key words "erythropoietin ,nervous system", we performed a search of Medline for English articles, which were published during September 1996 to August 2006, about EPO and EPOR in nervous system.STUDY SELECTION: The materials were selected firstly, literatures were chosen for treatment group and control group and those obviously non-randomized studies were excluded. The full texts of the left literatures were searched. Inclusive criteria: ① Randomized controlled study. ②Experimental or clinical studies (parallel control group included). ③Treatment group was recombinant human erythropoietin(rHuEPO)-treated group. Exclusive criteria: repetitive study.DATA EXTRACTION: A number of 380 randomized or non-randomized articles about the effect of EPO on nervous system were collected, and 49 experiments or clinical trials met the inclusive criteria. Among 331 exclusive articles, 237 were non-randomized or repetitive studies and 94 were review articles. DATA SYNTHESIS: Forty-nine experiments or clinical trials confirmed that EPO and EPOR were expressed in the central nervous system (CNS) and peripheral nervous system(PNS) of gnawer, primate and human being; rHuEPO had obvious neuroprotective effects on brain hypoxia, brain ischemia, experimental intracranial hemorrhage, brain trauma, experimental autoimmune encephalomyelitis, human immunodeficiency virus (HIV)-related sensory neuropathy, distal axonopathy, experimental diabetic neuropathy and acute spinal injury models. Its mechanism maybe involve anti-excitatory toxicity, preventing the production of nitric oxide (NO), lessening inflammatory reaction, resisting apoptosis, maintaining vascular integrity, promoting angiogenesis, promoting the proliferation and differentiation of neural stem cells and progenitor cells and so on. Exogenous EPO could be

  3. Erythropoietin.

    Jelkmann, Wolfgang

    2016-01-01

    Total hemoglobin (Hb) mass is an important determinant of aerobic power. The glycoprotein erythropoietin (Epo) promotes the production of red blood cells (RBCs). The present article reviews the regulation of erythropoiesis and ways of its manipulation. The various Epos, e.g. recombinant human (rh)Epo and (epoetin), and their long-acting analogues can be misused by cheating athletes, but the drugs are detectable by chemical tests, because their glycan isoform structures differ from those of endogenous Epo. Still, anti-doping control has become more difficult, since additional erythropoiesis-stimulating agents have become available (Epo mimetics, activin inhibitors, and small-molecule chemical drugs activating EPO expression). A major problem is created by hypoxia-inducible factor (HIF) stabilizers (e.g. α-ketoglutarate competitors and Co2+ salt) which activate HIFs and thus increase EPO expression. Direct EPO transfer is theoretically also possible but medically little advanced. To overcome weaknesses of direct testing of biological fluids, the World Anti-Doping Agency has implemented the Athlete Biological Passport for continuous monitoring of RBC parameters of athletes. Blood doping is assumed when distinct parameters (blood Hb concentration and reticulocytes) change in a nonphysiological way. PMID:27348128

  4. The Impact of Tumor Expression of Erythropoietin Receptors and Erythropoietin on Clinical Outcome of Esophageal Cancer Patients Treated With Chemoradiation

    Background: To investigate the impact of tumor erythropoietin receptors (Epo-R) and erythropoietin (Epo) expression in 64 patients with Stage III esophageal cancer receiving or not receiving erythropoietin during chemoradiation. Materials and Methods: The impact of tumor Epo-R expression, Epo expression, and 10 additional factors (age, Karnofsky-Performance-Score [KPS], tumor length, T and N stage, histology and grading, hemoglobin during radiotherapy, erythropoietin administration, surgery) on overall survival (OS) and locoregional control (LC) was evaluated. Results: Improved OS was associated with low (≤20%) Epo expression (p = 0.049), KPS >80 (p 0.008), T3 stage (p = 0.010), hemoglobin ≥12 g/dL (p < 0.001), and surgery (p = 0.010). Erythropoietin receptor expression showed a trend (p = 0.09). Locoregional control was associated with T stage (p = 0.005) and hemoglobin (p < 0.001), almost with erythropoietin administration (p = 0.06). On multivariate analyses, OS was associated with KPS (p = 0.045) and hemoglobin (p = 0.032), LC with hemoglobin (p < 0.001). Patients having low expression of both Epo-R and Epo had better OS (p = 0.003) and LC (p = 0.043) than others. Two-year OS was nonsignificantly better (p = 0.25) in patients with low Epo-R expression receiving erythropoietin (50%) than in those with higher Epo-R expression receiving erythropoietin (21%), low Epo-R expression/no erythropoietin administration (29%), or higher Epo-R expression/no erythropoietin administration (18%). Two-year LC rates were, respectively, 65%, 31%, 26%, and 29% (p = 0.20). Results for Epo expression were similar. Conclusions: Higher Epo-R expression or Epo expression seemed to be associated with poorer outcomes. Patients with low expression levels receiving erythropoietin seemed to do better than patients with higher expression levels or not receiving erythropoietin. The data need to be confirmed in a larger series of patients

  5. A new agonist of the erythropoietin receptor, Epobis, induces neurite outgrowth and promotes neuronal survival

    Pankratova, Stanislava; Gu, Bing; Kiryushko, Darya;

    2012-01-01

    Apart from its hematopoietic activity, erythropoietin (EPO) is also known as a tissue-protective cytokine. In the brain, EPO and its receptor are up-regulated in response to insult and exert pro-survival effects. EPO binds to its receptor (EPOR) via high- and low-affinity binding sites (Sites 1 and...... 2, respectively), inducing conformational changes in the receptor, followed by the activation of downstream signaling cascades. Based on the crystal structure of the EPO:EPOR(2) complex, we designed a peptide, termed Epobis, whose sequence encompassed amino acids from binding Site 1. The present...

  6. Functional significance of erythropoietin receptor on tumor cells

    Kodetthoor B Udupa

    2006-01-01

    Erythropoietin (Epo) is the regulator of red blood cell formation. Its receptor (EpoR) is now found in many cells and tissues of the body. EpoR is also shown to occur in tumor cells and Epo enhances the proliferation of these cells through cell signaling. EpoR antagonist can reduce the growth of the tumor in vivo. In view of our current knowledge of Epo, its recombinant forms and receptor,use of Epo in cancer patients to enhance the recovery of hematocrit after chemotherapy treatment has to be carefully evaluated.

  7. A dot assay for the erythropoietin receptor using human recombinant sup 125 I-erythropoietin

    Vannucchi, A.M.; Grossi, A.; Rafanelli, D.; Vannucchi, L.; Ferrini, P.R. (Univ. and USL 10/D, Florence (Italy))

    1989-10-01

    A dot assay was developed for the detection of membrane receptor(s) for erythropoietin (Ep). A relatively homogeneous population of cells bearing the receptor for Ep was generated in the spleen of mice made anemic with phenylhydrazine and crude membrane extracts were prepared from spleen cell suspensions. Aliquots of the membrane extracts were applied to microdishes of nitrocellulose in a volume of 4 microliters. After free reactive sites were blocked, the microdishes were incubated for 2 h at 37 degrees C with {sup 125}I-labeled human recombinant Ep ({sup 125}I-rEp), and nitrocellulose bound radioactivity was determined thereafter. Reproducible curves were obtained, and a significant correlation between bound radioactivity and the amount of membrane proteins applied to the nitrocellulose dishes was found. Specific binding was saturable, reaching a plateau at 2.5 nM. Binding parameters of nitrocellulose-immobilized receptor were not significantly different from the values calculated using intact cells. No appreciable binding of {sup 125}I-rEp to control membranes at low Ep-receptor content was observed. Among a panel of growth factors, only unlabeled rEp was able to compete for the binding of {sup 125}I-rEp to nitrocellulose-immobilized membrane proteins in a dose-dependent fashion. The technique described herein may be of use in the study of the Ep receptor and as an assay for its purification. Moreover, it may also be of general application in the study of receptor-ligand interactions.

  8. Physician Education: The Erythropoietin Receptor and Signal Transduction.

    Yoshimura; Arai

    1996-01-01

    ERYTHROPOIETIN (EPO): Erythropoietin (EPO) is a hormone that promotes the proliferation and differentiation of erythroid progenitor cells and regulates the number of erythrocytes in peripheral blood. EPO is produced mainly by the kidneys, and transcription of the EPO gene is promoted by a reduction in the oxygen concentration in the blood. The existence of EPO was suggested near the end of the 19th century by the discovery that hypoxia increases the production of red blood cells. EPO was identified as a serum factor in the 1950s, and in 1970 Miyake and coworkers succeeded in purifying it by using the urine of patients with aplastic anemia as a starting material. The human EPO gene was cloned in 1985 using a partial amino acid sequence from this purified EPO, and it is well known that recombinant EPO is currently used as a drug to treat anemia associated with chronic renal failure and other illnesses. ACTION OF EPO: When human bone marrow cells are cultured in a semisolid medium containing EPO, they form small erythroblast colonies in five to seven days, and by day 10 large erythroblast colonies appear that resemble fireworks ("burst" colonies). The original cells in the former colonies are called colony forming units-erythroid (CFU-E) or late-stage erythroblast progenitor cells and in the latter colonies they are called burst forming units-erythroid (BFU-E) or early-stage erythroblast progenitor cells. As shown in Figure 1, red blood cells are produced through differentiation from stem cells to BFU-E, CFU-E, and erythroblasts. Although EPO acts on both BFU-E and CFU-E cells, CFU-E cells show greater sensitivity to EPO, and other factors such as stem cell factor (SCF), interleukin (IL)-3, IL-4, and granulocyte macrophage colony-stimulating factor (GM-CSF) must be present together with EPO for BFU-E cell proliferation. In erythroblasts beyond the CFU-E stage, sensitivity to EPO decreases as the cells mature. THE EPO RECEPTOR AND THE CYTOKINE RECEPTOR FAMILY: The EPO

  9. An extra high dose of erythropoietin fails to support the proliferation of erythropoietin dependent cell lines

    ABE, Satoshi; Sasaki, Ryuzo; Masuda, Seiji

    2011-01-01

    Erythropoietin is responsible for the red blood cell formation by stimulating the proliferation and the differentiation of erythroid precursor cells. Erythropoietin triggers the conformational change in its receptor thereby induces the phosphorylation of JAK2. In this study, we show that an extra high dose of erythropoietin, however, fails to activate the erythropoietin receptor, to stimulate the phosphorylation of JAK2 and to support the cell proliferation of Ep-FDC-P2 cell. Moreover, high d...

  10. Human Erythropoietin Dimers with Markedly Enhanced in vivo Activity

    Sytkowski, Arthur J.; Dotimas Lunn, Elizabeth; Davis, Kerry Lynn; Feldman, Laurie; Siekman, Suvia

    1998-02-01

    Human erythropoietin, a widely used and important therapeutic glycoprotein, has a relatively short plasma half-life due to clearance by glomerular filtration as well as by other mechanisms. We hypothesized that an erythropoietin species with a larger molecular size would exhibit an increased plasma half-life and, potentially, an enhanced biological activity. We now report the production of biologically active erythropoietin dimers and trimers by chemical crosslinking of the conventional monomeric form. We imparted free sulfhydryl residues to a pool of erythropoietin monomer by chemical modification. A second pool was reacted with another modifying reagent to yield monomer with male-imido groups. Upon mixing these two pools, covalently linked dimers and trimers were formed that were biologically active in vitro. The plasma half-life of erythropoietin dimers in rabbits was >24 h compared with 4 h for the monomers. Importantly, erythropoietin dimers were biologically active in vivo as shown by their ability to increase the hematocrits of mice when injected subcutaneously. In addition, the dimers exhibited >26-fold higher activity in vivo than did the monomers and were very effective after only one dose. Dimeric and other oligomeric forms of Epo may have an important role in therapy.

  11. Erythropoietin receptor is expressed on human peripheral blood T and B lymphocytes and monocytes and is modulated by recombinant human erythropoietin treatment.

    Lisowska, Katarzyna A; Debska-Slizień, Alicja; Bryl, Ewa; Rutkowski, Bolesław; Witkowski, Jacek M

    2010-08-01

    Erythropoietin receptor (EPO-R) appears on the cell surface in the early stages of erythropoiesis. It has also been found on endothelial cells and polymorphonuclear leukocytes, suggesting erythropoietin (EPO) role beyond erythropoiesis itself. Earlier reports have shown that treatment with recombinant human erythropoietin (rhEPO) in chronic renal failure (CRF) patients improves interleukin-2 production and restores the T lymphocyte function. We decided to investigate possible expression of EPO-R on circulating peripheral blood lymphocytes and monocytes of CRF patients in order to assess the possibility of rhEPO direct action on these cells. Flow cytometry was used for detection and quantification of EPO-R, and reverse transcription polymerase chain reaction for detection of the EPO receptor mRNA. Our results show for the first time the existence of EPO-R on cell surface of human T and B lymphocytes and monocytes as well as at the transcriptional activity of the EPO-R gene in these cells, both in healthy and CRF individuals. We have also found significant differences between the numbers of EPO-R molecules on T and B lymphocytes of CRF patients not treated and treated with rhEPO and healthy control. Discovery of EPO-R expression on human lymphocytes suggests that EPO is probably able to directly modulate some signaling pathways important for these cells. PMID:20528849

  12. Redundant and selective roles for erythropoietin receptor tyrosines in erythropoiesis in vivo.

    Longmore, G D; You, Y; Molden, J; Liu, K D; Mikami, A; Lai, S Y; Pharr, P; Goldsmith, M A

    1998-02-01

    Cytokine receptors have been shown in cell culture systems to use phosphotyrosine residues as docking sites for certain signal transduction intermediates. Studies using various cellular backgrounds have yielded conflicting information about the importance of such residues. The present studies were undertaken to determine whether or not tyrosine residues within the erythropoietin receptor (EPOR) are essential for biologic activity during hematopoiesis in vivo. A variant of the EPOR was constructed that contains both a substitution (R129C) causing constitutive receptor activation as well as replacement of all eight cytoplasmic tyrosines by phenylalanines (cEPORYF). A comparison between animals exposed to recombinant retroviruses expressing cEPOR and cEPORYF showed that efficient red blood cell (RBC) development in vivo is dependent on the pressence of tyrosine residues in the cytoplasmic domain of the EPOR. In addition, an inefficient EPOR tyrosine independent pathway supporting RBC development was detected. Tyrosine add-back mutants showed that multiple individual tyrosines have the capacity to restore full erythropoietic potential to the EPOR as determined in whole animals. The analysis of primary erythroid progenitors transduced with the various cEPOR tyrosine mutants and tyrosine add-backs showed that only tyrosine 343 (Y1) and tyrosine 479 (Y8) were capable of supporting immature burst-forming unit-erythroid progenitor development. Thus, this receptor is characterized by striking functional redundancy of tyrosines in a biologically relevant context. However, selective tyrosine residues may be uniquely important for early signals supporting erythroid development. PMID:9446647

  13. Discovery and Characterization of Nonpeptidyl Agonists of the Tissue-Protective Erythropoietin Receptor.

    Miller, James L; Church, Timothy J; Leonoudakis, Dmitri; Lariosa-Willingham, Karen; Frigon, Normand L; Tettenborn, Connie S; Spencer, Jeffrey R; Punnonen, Juha

    2015-08-01

    Erythropoietin (EPO) and its receptor are expressed in a wide variety of tissues, including the central nervous system. Local expression of both EPO and its receptor is upregulated upon injury or stress and plays a role in tissue homeostasis and cytoprotection. High-dose systemic administration or local injection of recombinant human EPO has demonstrated encouraging results in several models of tissue protection and organ injury, while poor tissue availability of the protein limits its efficacy. Here, we describe the discovery and characterization of the nonpeptidyl compound STS-E412 (2-[2-(4-chlorophenoxy)ethoxy]-5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyrimidine), which selectively activates the tissue-protective EPO receptor, comprising an EPO receptor subunit (EPOR) and the common β-chain (CD131). STS-E412 triggered EPO receptor phosphorylation in human neuronal cells. STS-E412 also increased phosphorylation of EPOR, CD131, and the EPO-associated signaling molecules JAK2 and AKT in HEK293 transfectants expressing EPOR and CD131. At low nanomolar concentrations, STS-E412 provided EPO-like cytoprotective effects in primary neuronal cells and renal proximal tubular epithelial cells. The receptor selectivity of STS-E412 was confirmed by a lack of phosphorylation of the EPOR/EPOR homodimer, lack of activity in off-target selectivity screening, and lack of functional effects in erythroleukemia cell line TF-1 and CD34(+) progenitor cells. Permeability through artificial membranes and Caco-2 cell monolayers in vitro and penetrance across the blood-brain barrier in vivo suggest potential for central nervous system availability of the compound. To our knowledge, STS-E412 is the first nonpeptidyl, selective activator of the tissue-protective EPOR/CD131 receptor. Further evaluation of the potential of STS-E412 in central nervous system diseases and organ protection is warranted. PMID:26018904

  14. Cytoprotective doses of erythropoietin or carbamylated erythropoietin have markedly different procoagulant and vasoactive activities

    Coleman, TR; Westenfelder, C; Togel, FE; Yang, Y; Hu, ZM; Swenson, L; Leuvenink, HGD; Ploeg, RJ; d'Uscio, LV; Katusic, ZS; Ghezzi, P; Zanetti, A; Kaushansky, K; Fox, NE; Cerami, A; Brines, M

    2006-01-01

    Recombinant human erythropoietin (rhEPO) is receiving increasing attention as a potential therapy for prevention of injury and restoration of function in nonhematopoietic tissues. However, the minimum effective dose required to mimic and augment these normal paracrine functions of erythropoietin (EP

  15. Action of erythropoietin in vitro on rabbit reticulocyte membrane Ca2+-ATPase activity.

    Lawrence, W D; Davis, P J; Blas, S D

    1987-01-01

    The mechanism of action of erythropoietin is thought to require specific interaction with the target cell surface and involve alteration of cellular calcium metabolism. Using the rabbit reticulocyte membrane as a model of the immature red cell membrane, we investigated the effects of human recombinant erythropoietin on membrane Ca2+-ATPase (calcium pump) activity in vitro. Erythropoietin in a concentration range of 0.025 to 3.0 U/ml progressively decreased membrane Ca2+-ATPase activity by up ...

  16. Packing Density of the Erythropoietin Receptor Transmembrane Domain Correlates with Amplification of Biological Responses

    Becker, Verena [German Cancer Research Center, Heidelberg; Sengupta, D [University of Heidelberg; Ketteler, Robin [German Cancer Research Center, Heidelberg; Ullmann, G. Matthias [University of Bayreuth; Smith, Jeremy C [ORNL; Klingmuller, Ursula [German Cancer Research Center, Heidelberg

    2008-10-01

    The formation of signal-promoting dimeric or oligomeric receptor complexes at the cell surface is modulated by self-interaction of their transmembrane (TM) domains. To address the importance of TM domain packing density for receptor functionality, we examined a set of asparagine mutants in the TM domain of the erythropoietin receptor (EpoR). We identified EpoR-T242N as a receptor variant that is present at the cell surface similar to wild-type EpoR but lacks visible localization in vesicle-like structures and is impaired in efficient activation of specific signaling cascades. Analysis by a molecular modeling approach indicated an increased interhelical distance for the EpoR-T242N TM dimer. By employing the model, we designed additional mutants with increased or decreased packing volume and confirmed a correlation between packing volume and biological responsiveness. These results propose that the packing density of the TM domain provides a novel layer for fine-tuned regulation of signal transduction and cellular decisions.

  17. Erythropoietin regulates Treg cells in asthma through TGFβ receptor signaling

    Wan, Guoshi; Wei, Bing

    2015-01-01

    Asthma is a chronic inflammatory disorder of the airways, the development of which is suppressed by regulatory T cells (Treg). Erythropoietin (EPO) is originally defined as a hematopoietic growth factor. Recently, the anti-inflammatory effects of EPO in asthma have been acknowledged. However, the underlying mechanisms remain ill-defined. Here, we showed that EPO treatment significantly reduced the severity of an ovalbumin (OVA)-induced asthma in mice, seemingly through promoting Foxp3-mediate...

  18. Erythropoietin, ferritin, haptoglobin, hemoglobin and transferrin receptor in metabolic syndrome: a case control study

    Hämäläinen Päivi

    2012-09-01

    Full Text Available Abstract Background Increased ferritin concentrations are associated with metabolic syndrome (MetS. The association between ferritin as well as hemoglobin level and individual MetS components is unclear. Erythropoietin levels in subjects with MetS have not been determined previously. The aim of this study was to compare serum erythropoietin, ferritin, haptoglobin, hemoglobin, and transferrin receptor (sTFR levels between subjects with and without MetS and subjects with individual MetS components. Methods A population based cross-sectional study of 766 Caucasian, middle-aged subjects (341 men and 425 women from five age groups born in Pieksämäki, Finland who were invited to a health check-up in 2004 with no exclusion criteria. Laboratory analyzes of blood samples collected in 2004 were done during year 2010. MetS was defined by National Cholesterol Education Program criteria. Results 159 (53% men and 170 (40% women of study population met MetS criteria. Hemoglobin and ferritin levels as well as erythropoietin and haptoglobin levels were higher in subjects with MetS (p  Conclusion Subjects with MetS have elevated hemoglobin, ferritin, erythropoietin and haptoglobin concentrations. Higher hemoglobin levels are related to all components of MetS. Higher ferritin levels associate with TG, abdominal obesity, elevated glucose or low high density cholesterol. Haptoglobin levels associate with blood pressure or elevated glucose. However, erythropoietin levels are related only with abdominal obesity. Higher serum erythropoietin concentrations may suggest underlying adipose tissue hypoxemia in MetS.

  19. Expression of platelet-derived growth factor BB, erythropoietin and erythropoietin receptor in canine and feline osteosarcoma

    Meyer, F.R.L.; Steinborn, R.; Grausgruber, H.; Wolfesberger, B.; Walter, I.

    2015-01-01

    The discovery of expression of the erythropoietin receptor (EPO-R) on neoplastic cells has led to concerns about the safety of treating anaemic cancer patients with EPO. In addition to its endocrine function, the receptor may play a role in tumour progression through an autocrine mechanism. In this study, the expression of EPO, EPO-R and platelet-derived growth factor BB (PDGF-BB) was analysed in five feline and 13 canine osteosarcomas using immunohistochemistry (IHC) and reverse transcription polymerase chain reaction (RT-PCR). EPO expression was positive in all tumours by IHC, but EPO mRNA was only detected in 38% of the canine and 40% of the feline samples. EPO-R was expressed in all samples by quantitative RT-PCR (RT-qPCR) and IHC. EPO-R mRNA was expressed at higher levels in all feline tumours, tumour cell lines, and kidney when compared to canine tissues. PDGF-BB expression was variable by IHC, but mRNA was detected in all samples. To assess the functionality of the EPO-R on tumour cells, the proliferation of canine and feline osteosarcoma cell lines was evaluated after EPO administration using an alamarBlue assay and Ki67 immunostaining. All primary cell lines responded to EPO treatment in at least one of the performed assays, but the effect on proliferation was very low indicating only a weak responsiveness of EPO-R. In conclusion, since EPO and its receptor are expressed by canine and feline osteosarcomas, an autocrine or paracrine tumour progression mechanism cannot be excluded, although in vitro data suggest a minimal role of EPO-R in osteosarcoma cell proliferation. PMID:26189892

  20. Systemic and cerebral vascular endothelial growth factor levels increase in murine cerebral malaria along with increased calpain and caspase activity and can be reduced by erythropoietin treatment

    Casper eHempel

    2014-06-01

    Full Text Available The pathogenesis of cerebral malaria includes compromised microvascular perfusion, increased inflammation, cytoadhesion and endothelial activation. These events cause blood-brain barrier disruption and neuropathology and can be associated with the vascular endothelial growth factor (VEGF signalling pathway. We studied this pathway in mice infected with Plasmodium berghei ANKA causing murine cerebral malaria with or without the use of erythropoietin as adjunct therapy. ELISA and western blotting was used for quantification of VEGF and relevant proteins in brain and plasma. Cerebral malaria increased levels of VEGF in brain and plasma and decreased plasma levels of soluble VEGF receptor 2. Erythropoietin treatment normalised VEGF receptor 2 levels and reduced brain VEGF levels. Hypoxia-inducible factor (HIF-1α was significantly upregulated whereas cerebral HIF-2α and erythropoietin levels remained unchanged. Furthermore, we noticed increased caspase-3 and calpain activity in terminally ill mice, as measured by protease-specific cleavage of α-spectrin and p35. In conclusion, we detected increased cerebral and systemic VEGF as well as HIF-1α, which in the brain were reduced to normal in erythropoietin-treated mice. Also caspase and calpain activity was reduced markedly in erythropoietin-treated mice.

  1. Expression and characterization of erythropoietin receptors on normal human bone marrow cells

    Hoshino, S.; Teramura, M.; Takahashi, M.; Motoji, T.; Oshimi, K.; Ueda, M.; Mizoguchi, H.

    1989-05-01

    We studied the specific binding of /sup 125/I-labeled bioactive recombinant human erythropoietin (Epo) to human bone marrow mononuclear cells (BMNC) obtained from normal subjects. The /sup 125/I-labeled Epo bound specifically to the BMNC. Scatchard analysis of the data showed two classes of binding sites; one high affinity (Kd 0.07 nM) and the other low affinity (Kd 0.38 nM). The number of Epo binding sites per BMNC was 46 +/- 16 high-affinity receptors and 91 +/- 51 low-affinity receptors. The specific binding was displaced by unlabeled Epo, but not by other growth factors. Receptor internalization was observed significantly at 37 degrees C, but was prevented by the presence of 0.2% sodium azide. These findings indicate that human BMNC possess two classes of specific Epo receptors with characteristics of a hormone-receptor association.

  2. Problem-Solving Test: Expression Cloning of the Erythropoietin Receptor

    Szeberenyi, Jozsef

    2008-01-01

    Terms to be familiar with before you start to solve the test: cytokines, cytokine receptors, cDNA library, cDNA synthesis, poly(A)[superscript +] RNA, primer, template, reverse transcriptase, restriction endonucleases, cohesive ends, expression vector, promoter, Shine-Dalgarno sequence, poly(A) signal, DNA helicase, DNA ligase, topoisomerases,…

  3. Comparison of real time RT-PCR and flow cytometry methods for evaluation of biological activity of recombinant human erythropoietin

    Sepehrizadeh Z; Tabatabaei Yazdi M; Zarrini GH; Hashemi Bozchlou S; Khoshakhlagh P

    2008-01-01

    Background: Evaluation of bioactivity of recombinant erythropoietin is essential for pharmaceutical industry, quality control authorities and researchers. The purpose of this study was to compare real time RT-PCR and flow cytometry for the assay of biological activity of recombinant erythropoietin. Methods: Three concentrations of recombinant erythropoietin BRP (80, 40 and 20 IU/ml) were injected subcutaneously to mice. After 4 days the blood was collected and used for reticulocyte counts by ...

  4. Simulated microgravity induce apoptosis and down-regulation of erythropoietin receptor of UT-7/EPO cells

    Zou, Li-xue; Cui, Shao-yan; Zhong, Jian; Yi, Zong-chun; Sun, Yan; Fan, Yu-bo; Zhuang, Feng-yuan

    2010-11-01

    Hematopoietic progenitor cell proliferation can be alternated on either spaceflight or under simulated microgravity experiments on the ground; however, the underlying mechanism remains largely unknown. In the present study, we have demonstrated that exposure of human erythropoietin (EPO)-dependent leukemia cell line UT-7/EPO cells to conditions of simulated microgravity with a rotary culture instrument significantly inhibited the cellular proliferation rate. Adding higher concentrations of EPO to the culture medium failed to improve the inhibitory status. Cell apoptosis was detected by fluorescence staining of cell nuclei and a flow cytometry assay using Annexin V/PI double staining. This microgravity-induced apoptosis in UT-7/EPO cells could be blocked by a pancaspase inhibitor Z-VAD-FMK. Immunoblotting demonstrated that rotary culture resulted in a reduction of the expression of Bcl-xL, an anti-apoptotic protein, and the cleavage of caspase-3. Furthermore, rotary culture reduced surface localization and protein content, as well as the mRNA expression of erythropoietin receptor (EPOR) of UT-7/EPO. Take together, the findings indicated that simulated microgravity may induce mitochondrial related apoptosis of UT-7/EPO cell through depressing the EPO-EPOR pathway.

  5. Upregulation of erythropoietin receptor in UT-7/EPO cells inhibits simulated microgravity-induced cell apoptosis

    Zou, Li-xue; Cui, Shao-yan; Zhong, Jian; Yi, Zong-chun; Sun, Yan; Fan, Yu-bo; Zhuang, Feng-yuan

    2011-07-01

    Hematopoietic progenitor cell proliferation can be altered in either spaceflight or under simulated microgravity experiments on the ground, however, the underlying mechanism remains unknown. Our previous study showed that exposure of the human erythropoietin (EPO)-dependent leukemia cell line UT-7/EPO to conditions of simulated microgravity significantly inhibited the cellular proliferation rate and induced cell apoptosis. We postulated that the downregulation of the erythropoietin receptor (EPOR) expression in UT-7/EPO cells under simulated microgravity may be a possible reason for microgravity triggered apoptosis. In this paper, a human EPOR gene was transferred into UT-7/EPO cells and the resulting expression of EPOR on the surface of UT-7/EPO cells increased approximately 61% ( p < 0.05) as selected by the antibiotic G418. It was also shown through cytometry assays and morphological observations that microgravity-induced apoptosis markedly decreased in these UT-7/EPO-EPOR cells. Thus, we concluded that upregulation of EPOR in UT-7/EPO cells could inhibit the simulated microgravity-induced cell apoptosis in this EPO dependent cell line.

  6. Erythropoietin signaling promotes transplanted progenitor cell survival

    Jia, Yi; Warin, Renaud; Yu, Xiaobing; Epstein, Reed; Noguchi, Constance Tom

    2009-01-01

    We examine the potential for erythropoietin signaling to promote donor cell survival in a model of myoblast transplantation. Expression of a truncated erythropoietin receptor in hematopoietic stem cells has been shown to promote selective engraftment in mice. We previously demonstrated expression of endogenous erythropoietin receptor on murine myoblasts, and erythropoietin treatment can stimulate myoblast proliferation and delay differentiation. Here, we report that enhanced erythropoietin re...

  7. Targeting the erythropoietin receptor on glioma cells reduces tumour growth

    Hypoxia has been shown to be one of the major events involved in EPO expression. Accordingly, EPO might be expressed by cerebral neoplastic cells, especially in glioblastoma, known to be highly hypoxic tumours. The expression of EPOR has been described in glioma cells. However, data from the literature remain descriptive and controversial. On the basis of an endogenous source of EPO in the brain, we have focused on a potential role of EPOR in brain tumour growth. In the present study, with complementary approaches to target EPO/EPOR signalling, we demonstrate the presence of a functional EPO/EPOR system on glioma cells leading to the activation of the ERK pathway. This EPO/EPOR system is involved in glioma cell proliferation in vitro. In vivo, we show that the down-regulation of EPOR expression on glioma cells reduces tumour growth and enhances animal survival. Our results support the hypothesis that EPOR signalling in tumour cells is involved in the control of glioma growth.

  8. Targeting the erythropoietin receptor on glioma cells reduces tumour growth

    Peres, Elodie A.; Valable, Samuel [CERVOxy team ' Hypoxia and cerebrovascular pathophysiology' , UMR 6232 CI-NAPS, Universite de Caen Basse-Normandie, Universite Paris-Descartes, CNRS, CEA. G.I.P. CYCERON, Caen (France); Guillamo, Jean-Sebastien [CERVOxy team ' Hypoxia and cerebrovascular pathophysiology' , UMR 6232 CI-NAPS, Universite de Caen Basse-Normandie, Universite Paris-Descartes, CNRS, CEA. G.I.P. CYCERON, Caen (France); Departement de Neurologie, CHU de Caen (France); Marteau, Lena [CERVOxy team ' Hypoxia and cerebrovascular pathophysiology' , UMR 6232 CI-NAPS, Universite de Caen Basse-Normandie, Universite Paris-Descartes, CNRS, CEA. G.I.P. CYCERON, Caen (France); Bernaudin, Jean-Francois [Service d' Histologie-Biologie Tumorale, ER2UPMC, Universite Paris 6, Hopital Tenon, Paris (France); Roussel, Simon [CERVOxy team ' Hypoxia and cerebrovascular pathophysiology' , UMR 6232 CI-NAPS, Universite de Caen Basse-Normandie, Universite Paris-Descartes, CNRS, CEA. G.I.P. CYCERON, Caen (France); Lechapt-Zalcman, Emmanuele [CERVOxy team ' Hypoxia and cerebrovascular pathophysiology' , UMR 6232 CI-NAPS, Universite de Caen Basse-Normandie, Universite Paris-Descartes, CNRS, CEA. G.I.P. CYCERON, Caen (France); Service d' Anatomie Pathologique, CHU de Caen (France); Bernaudin, Myriam [CERVOxy team ' Hypoxia and cerebrovascular pathophysiology' , UMR 6232 CI-NAPS, Universite de Caen Basse-Normandie, Universite Paris-Descartes, CNRS, CEA. G.I.P. CYCERON, Caen (France); Petit, Edwige, E-mail: epetit@cyceron.fr [CERVOxy team ' Hypoxia and cerebrovascular pathophysiology' , UMR 6232 CI-NAPS, Universite de Caen Basse-Normandie, Universite Paris-Descartes, CNRS, CEA. G.I.P. CYCERON, Caen (France)

    2011-10-01

    Hypoxia has been shown to be one of the major events involved in EPO expression. Accordingly, EPO might be expressed by cerebral neoplastic cells, especially in glioblastoma, known to be highly hypoxic tumours. The expression of EPOR has been described in glioma cells. However, data from the literature remain descriptive and controversial. On the basis of an endogenous source of EPO in the brain, we have focused on a potential role of EPOR in brain tumour growth. In the present study, with complementary approaches to target EPO/EPOR signalling, we demonstrate the presence of a functional EPO/EPOR system on glioma cells leading to the activation of the ERK pathway. This EPO/EPOR system is involved in glioma cell proliferation in vitro. In vivo, we show that the down-regulation of EPOR expression on glioma cells reduces tumour growth and enhances animal survival. Our results support the hypothesis that EPOR signalling in tumour cells is involved in the control of glioma growth.

  9. Photoaffinity labeling of the erythropoietin receptor and its identification in a ligand-free form

    Hosoi, Takayuki; Sawyer, S.T.; Krantz, S.B. (Vanderbilt Univ. School of Medicine, Nashville, TN (USA))

    1991-01-01

    Pure human recombinant erythropoietin (EP) was acylated through a primary amino residue with a cross-linking reagent, N-((3-((4-((p-azido-m-({sup 125}I)iodophenyl)azo)benzoyl)amino)propanoyl)oxy)-succinimide (Denny-Jaffe reagent), which is photoreactive and cleavable at the azo residue. The resulting conjugated hormone (DJ-EP) was purified from unmodified EP by reverse-phase high-pressure liquid chromatography and maintained its capacity to bind to receptors for EP on erythroid progenitor cells. The receptor for EP was previously identified as two related proteins of 100 and 85 kDa molecular mass by chemical cross-linking to {sup 125}I-EP. Recently, D'Andrea and co-workers cloned a cDNA that codes for a protein of 55-66 kDa, which is thought to be the EP receptor. In this report, cross-linking to the receptor through the monofunctional DJ-EP labeled the same 140- and 125-kDa molecular mass bands cross-linked with {sup 125}I-EP and disuccinimidyl suberate. Furthermore, cleavage of the azo bond of the DJ-EP receptor complex by sodium dithionite demonstrated that proteins of 105 and 90 kDa were labeled in ligand-free form by DJ-EP. This result demonstrates that artifactual cross-linking of multiple proteins or other artifacts of cross-linking do not explain the difference in molecular mass of the EP receptor identified by cross-linking and the receptor identified by expression cloning.

  10. Erythropoietin in cardiac disease : New features of an old drug

    Ruifrok, Willem-Peter T.; de Boer, Rudolf A.; Westenbrink, B. Daan; van Veldhuisen, Dirk J.; van Gilst, Wiek H.

    2008-01-01

    Erythropoietin is a haematopoietic hormone with extensive non-haematopoietic effects. The discovery of an erythropoietin receptor outside the haematopoietic system has fuelled the research into the beneficial effects of erythropoietin for various conditions, predominantly in cardiovascular disease.

  11. Expression of functionally active sialylated human erythropoietin in plants

    Jez, Jakub; Castilho, Alexandra; Grass, Josephine; Vorauer-Uhl, Karola; Sterovsky, Thomas; Altmann, Friedrich; Steinkellner, Herta

    2013-01-01

    Recombinant human erythropoietin (rhEPO), a glycohormone, is one of the leading biopharmaceutical products. The production of rhEPO is currently restricted to mammalian cell expression systems because of rhEPO's highly complex glycosylation pattern, which is a major determinant for drug-efficacy. Here we evaluate the ability of plants to produce different glycoforms of rhEPO. cDNA constructs were delivered to Nicotiana benthamiana (N. benthamiana) and transiently expressed by a viral based ex...

  12. Lenalidomide Stabilizes the Erythropoietin Receptor by Inhibiting the E3 Ubiquitin Ligase RNF41.

    Basiorka, Ashley A; McGraw, Kathy L; De Ceuninck, Leentje; Griner, Lori N; Zhang, Ling; Clark, Justine A; Caceres, Gisela; Sokol, Lubomir; Komrokji, Rami S; Reuther, Gary W; Wei, Sheng; Tavernier, Jan; List, Alan F

    2016-06-15

    In a subset of patients with non-del(5q) myelodysplastic syndrome (MDS), lenalidomide promotes erythroid lineage competence and effective erythropoiesis. To determine the mechanism by which lenalidomide promotes erythropoiesis, we investigated its action on erythropoietin receptor (EpoR) cellular dynamics. Lenalidomide upregulated expression and stability of JAK2-associated EpoR in UT7 erythroid cells and primary CD71+ erythroid progenitors. The effects of lenalidomide on receptor turnover were Type I cytokine receptor specific, as evidenced by coregulation of the IL3-Rα receptor but not c-Kit. To elucidate this mechanism, we investigated the effects of lenalidomide on the E3 ubiquitin ligase RNF41. Lenalidomide promoted EpoR/RNF41 association and inhibited RNF41 auto-ubiquitination, accompanied by a reduction in EpoR ubiquitination. To confirm that RNF41 is the principal target responsible for EpoR stabilization, HEK293T cells were transfected with EpoR and/or RNF41 gene expression vectors. Steady-state EpoR expression was reduced in EpoR/RNF41 cells, whereas EpoR upregulation by lenalidomide was abrogated, indicating that cellular RNF41 is a critical determinant of drug-induced receptor modulation. Notably, shRNA suppression of CRBN gene expression failed to alter EpoR upregulation, indicating that drug-induced receptor modulation is independent of cereblon. Immunohistochemical staining showed that RNF41 expression decreased in primary erythroid cells of lenalidomide-responding patients, suggesting that cellular RNF41 expression merits investigation as a biomarker for lenalidomide response. Our findings indicate that lenalidomide has E3 ubiquitin ligase inhibitory effects that extend to RNF41 and that inhibition of RNF41 auto-ubiquitination promotes membrane accumulation of signaling competent JAK2/EpoR complexes that augment Epo responsiveness. Cancer Res; 76(12); 3531-40. ©2016 AACR. PMID:27197154

  13. Erythropoietin receptor expression is a potential prognostic factor in human lung adenocarcinoma.

    Anita Rózsás

    Full Text Available Recombinant human erythropoietins (rHuEPOs are used to treat cancer-related anemia. Recent preclinical studies and clinical trials, however, have raised concerns about the potential tumor-promoting effects of these drugs. Because the clinical significance of erythropoietin receptor (EPOR signaling in human non-small cell lung cancer (NSCLC also remains controversial, our aim was to study whether EPO treatment modifies tumor growth and if EPOR expression has an impact on the clinical behavior of this malignancy. A total of 43 patients with stage III-IV adenocarcinoma (ADC and complete clinicopathological data were included. EPOR expression in human ADC samples and cell lines was measured by quantitative real-time polymerase chain reaction. Effects of exogenous rHuEPOα were studied on human lung ADC cell lines in vitro. In vivo growth of human ADC xenografts treated with rHuEPOα with or without chemotherapy was also assessed. In vivo tumor and endothelial cell (EC proliferation was determined by 5-bromo-2'-deoxy-uridine (BrdU incorporation and immunofluorescent labeling. Although EPOR mRNA was expressed in all of the three investigated ADC cell lines, rHuEPOα treatment (either alone or in combination with gemcitabine did not alter ADC cell proliferation in vitro. However, rHuEPOα significantly decreased tumor cell proliferation and growth of human H1975 lung ADC xenografts. At the same time, rHuEPOα treatment of H1975 tumors resulted in accelerated tumor endothelial cell proliferation. Moreover, in patients with advanced stage lung ADC, high intratumoral EPOR mRNA levels were associated with significantly increased overall survival. This study reveals high EPOR level as a potential novel positive prognostic marker in human lung ADC.

  14. Widespread Expression of Erythropoietin Receptor in Brain and Its Induction by Injury

    Ott, Christoph; Martens, Henrik; Hassouna, Imam; Oliveira, Bárbara; Erck, Christian; Zafeiriou, Maria-Patapia; Peteri, Ulla-Kaisa; Hesse, Dörte; Gerhart, Simone; Altas, Bekir; Kolbow, Tekla; Stadler, Herbert; Kawabe, Hiroshi; Zimmermann, Wolfram-Hubertus; Nave, Klaus-Armin; Schulz-Schaeffer, Walter; Jahn, Olaf; Ehrenreich, Hannelore

    2015-01-01

    Erythropoietin (EPO) exerts potent neuroprotective, neuroregenerative and procognitive functions. However, unequivocal demonstration of erythropoietin receptor (EPOR) expression in brain cells has remained difficult since previously available anti-EPOR antibodies (EPOR-AB) were unspecific. We report here a new, highly specific, polyclonal rabbit EPOR-AB directed against different epitopes in the cytoplasmic tail of human and murine EPOR and its characterization by mass spectrometric analysis of immuno-precipitated endogenous EPOR, Western blotting, immunostaining and flow cytometry. Among others, we applied genetic strategies including overexpression, Lentivirus-mediated conditional knockout of EpoR and tagged proteins, both on cultured cells and tissue sections, as well as intracortical implantation of EPOR-transduced cells to verify specificity. We show examples of EPOR expression in neurons, oligodendroglia, astrocytes and microglia. Employing this new EPOR-AB with double-labeling strategies, we demonstrate membrane expression of EPOR as well as its localization in intracellular compartments such as the Golgi apparatus. Moreover, we show injury-induced expression of EPOR. In mice, a stereotactically applied stab wound to the motor cortex leads to distinct EpoR expression by reactive GFAP-expressing cells in the lesion vicinity. In a patient suffering from epilepsy, neurons and oligodendrocytes of the hippocampus strongly express EPOR. To conclude, this new analytical tool will allow neuroscientists to pinpoint EPOR expression in cells of the nervous system and to better understand its role in healthy conditions, including brain development, as well as under pathological circumstances, such as upregulation upon distress and injury. PMID:26349059

  15. Macrophages as novel targets for erythropoietin

    Lifshitz, L; Tabak, G; Mittelman, M.; Gassmann, M.; Neumann, D.

    2010-01-01

    BackgroundOur original demonstration of immunomodulatory effects of erythropoietin in multiple myeloma, led us to the search of the cells in the immune system that are direct targets to erythropoietin. The finding that lymphocytes do not express erythropoietin receptors, has led to the hypothesis that other cells act as direct targets and thus mediate the erythropoietin effects. Having found erythropoietin effects on dendritic cells thus led to the question of whether macrophages act as targe...

  16. Agonists of the tissue-protective erythropoietin receptor in the treatment of Parkinson's disease.

    Punnonen, Juha; Miller, James L; Collier, Timothy J; Spencer, Jeffrey R

    2015-01-01

    Parkinson's disease (PD) is a neurodegenerative disease affecting more than a million people in the USA alone. While there are effective symptomatic treatments for PD, there is an urgent need for new therapies that slow or halt the progressive death of dopaminergic neurons. Significant progress has been made in understanding the pathophysiology of PD, which has substantially facilitated the discovery efforts to identify novel drugs. The tissue-protective erythropoietin (EPO) receptor, EPOR/CD131, has emerged as one promising target for disease-modifying therapies. Recombinant human EPO (rhEPO), several variants of EPO, EPO-mimetic peptides, cell-based therapies using cells incubated with or expressing EPO, gene therapy vectors encoding EPO, and small molecule EPO mimetic compounds all show potential as therapeutic candidates. Agonists of the EPOR/CD131 receptor demonstrate potent anti-apoptotic, antioxidant, and anti-inflammatory effects and protect neurons, including dopaminergic neurons, from diverse insults in vitro and in vivo. When delivered directly to the striatum, rhEPO protects dopaminergic neurons in animal models of PD. Early-stage clinical trials testing systemic rhEPO have provided encouraging results, while additional controlled studies are required to fully assess the potential of the treatment. Poor CNS availability of proteins and challenges related to invasive delivery limit delivery of EPO protein. Several variants of EPO and small molecule agonists of the EPO receptors are making progress in preclinical studies and may offer solutions to these challenges. While EPO was initially discovered as the primary modulator of erythropoiesis, the discovery and characterization of the tissue-protective EPOR/CD131 receptor offer an opportunity to selectively target the neuroprotective receptor as an approach to identify disease-modifying treatments for PD. PMID:25832721

  17. Study of the erythropoiesis activity of nano-encapsulated forms of erythropoietin

    Zhanagul Khasenbekova

    2014-01-01

    Full Text Available Introduction: The recombinant human erythropoietin (rhEPO is used in the treatment of anemia. In order to improve its pharmacokinetic properties, nanoparticles of biodegradable polymers of natural or synthetic origin were used. The aim of this study was to investigate the effect of new nano-encapsulated forms of recombinant human erythropoietin for oral use on the erythropoiesis in the cyclophosphamide immunosuppression model. Material and methods: The CHOpE immortalized cells culture (a primary producer of rhEPO "Vector" in Russia was used. The following biodegradable polymers were chosen: 0.05% and 0.005% carbopol, 0.05% and 0.005% kollidon, and 0.05% and 0.005% pectin. Immunosuppression was obtained by a single dose of i.p. injection of cyclophosphamide (250 mg/kg in white mice (18-20 g. During the next 5 days, the nano-encapsulated erythropoietin (100 ED/mouse was administered orally to each mouse. After 5 and 10 days, the cell count of the number of blood reticulocytes and the myelogram of bone marrow were performed. The control group of mice received injections of Eprex. Results: On the 5th day of the experiment, the highest level of reticulocyte was observed in the samples of erythropoietin with kollidon (0.05% and pectin (0.005% nanoparticles. On the 10th day, the highest activity was observed in the samples of erythropoietin substance with pectin at 0.05% and 0.005% concentrations. The levels of reticulocytes in these groups reached 13.53% and 14.55%, respectively. The results of the myelogram during immunosuppression showed some activity of erythropoietin in conjunction with both concentrations of pectin when a two-fold increase in the number of erythroblasts was observed on the 5th day. High degrees of erythrokaryocytes in the state of mitosis were observed in the 0.05% pectin samples. Similar results were observed in equivalent groups of control animals on the 10th day of the experiment, which is compatible with the data on Eprex

  18. Erythropoietin -induced proliferation of gastric mucosal cells

    Itoh, Kazuro; Sawasaki, Yoshio; Takeuchi, Kyoko; Kato, Shingo; Imai, Nobuhiro; Kato, Yoichiro; Shibata, Noriyuki; KOBAYASHI, MAKIO; Moriguchi, Yoshiyuki; Higuchi, Masato; Ishihata, Fumio; Sudoh, Yushi; Miura, Soichiro

    2006-01-01

    AIM: To analyze the localization of erythropoietin receptor on gastric specimens and characterize the effects of erythropoietin on the normal gastric epithelial proliferation using a porcine gastric epithelial cell culture model.

  19. Lenalidomide induces lipid raft assembly to enhance erythropoietin receptor signaling in myelodysplastic syndrome progenitors.

    Kathy L McGraw

    Full Text Available Anemia remains the principal management challenge for patients with lower risk Myelodysplastic Syndromes (MDS. Despite appropriate cytokine production and cellular receptor display, erythropoietin receptor (EpoR signaling is impaired. We reported that EpoR signaling is dependent upon receptor localization within lipid raft microdomains, and that disruption of raft integrity abolishes signaling capacity. Here, we show that MDS erythroid progenitors display markedly diminished raft assembly and smaller raft aggregates compared to normal controls (p = 0.005, raft number; p = 0.023, raft size. Because lenalidomide triggers raft coalescence in T-lymphocytes promoting immune synapse formation, we assessed effects of lenalidomide on raft assembly in MDS erythroid precursors and UT7 cells. Lenalidomide treatment rapidly induced lipid raft formation accompanied by EpoR recruitment into raft fractions together with STAT5, JAK2, and Lyn kinase. The JAK2 phosphatase, CD45, a key negative regulator of EpoR signaling, was displaced from raft fractions. Lenalidomide treatment prior to Epo stimulation enhanced both JAK2 and STAT5 phosphorylation in UT7 and primary MDS erythroid progenitors, accompanied by increased STAT5 DNA binding in UT7 cells, and increased erythroid colony forming capacity in both UT7 and primary cells. Raft induction was associated with F-actin polymerization, which was blocked by Rho kinase inhibition. These data indicate that deficient raft integrity impairs EpoR signaling, and provides a novel strategy to enhance EpoR signal fidelity in non-del(5q MDS.

  20. Erythropoietin in Brain Development and Beyond

    Mawadda Alnaeeli; Li Wang; Barbora Piknova; Heather Rogers; Xiaoxia Li; Constance Tom Noguchi

    2012-01-01

    Erythropoietin is known as the requisite cytokine for red blood cell production. Its receptor, expressed at a high level on erythroid progenitor/precursor cells, is also found on endothelial, neural, and other cell types. Erythropoietin and erythropoietin receptor expression in the developing and adult brain suggest their possible involvement in neurodevelopment and neuroprotection. During ischemic stress, erythropoietin, which is hypoxia inducible, can contribute to brain homeostasis by incr...

  1. In-vivo detection of the erythropoietin receptor in tumours using positron emission tomography

    Fuge, Felix; Doleschel, Dennis; Rix, Anne; Gremse, Felix; Lederle, Wiltrud; Kiessling, Fabian [RWTH Aachen University, Department for Experimental Molecular Imaging (ExMI), Medical Faculty, Aachen (Germany); Wessner, Axel [Roche Diagnostics GmbH, R and D RPD Protein Chemistry, Penzberg (Germany); Winz, Oliver; Mottaghy, Felix [University Clinic RWTH Aachen, Clinic for Nuclear Medicine, Aachen (Germany)

    2014-09-09

    Recombinant human erythropoietin (rhuEpo) is used clinically to treat anaemia. However, rhuEpo-treated cancer patients show decreased survival rates and erythropoietin receptor (EpoR) expression has been found in patient tumour tissue. Thus, rhuEpo application might promote EpoR{sup +} tumour progression. We therefore developed the positron emission tomography (PET)-probe {sup 68}Ga-DOTA-rhuEpo and evaluated its performance in EpoR{sup +} A549 non-small-cell lung cancer (NSCLC) xenografts. {sup 68}Ga-DOTA-rhuEpo was generated by coupling DOTA-hydrazide to carbohydrate side-chains of rhuEpo. Biodistribution was determined in tumour-bearing mice 0.5, 3, 6, and 9 h after probe injection. Competition experiments were performed by co-injecting {sup 68}Ga-DOTA-rhuEpo and rhuEpo in five-fold excess. Probe specificity was further evaluated histologically using Epo-Cy5.5 stainings. The blood half-life of {sup 68}Ga-DOTA-rhuEpo was 2.6 h and the unbound fraction was cleared by the liver and kidney. After 6 h, the highest tumour to muscle ratio was reached. The highest {sup 68}Ga-DOTA-rhuEpo accumulation was found in liver (10.06 ± 6.26%ID/ml), followed by bone marrow (1.87 ± 0.53%ID/ml), kidney (1.58 ± 0.39 %ID/ml), and tumour (0.99 ± 0.16%ID/ml). EpoR presence in these organs was histologically confirmed. Competition experiments showed significantly (p < 0.05) lower PET-signals in tumour and bone marrow at 3 and 6 h. {sup 68}Ga-DOTA-rhuEpo shows favourable pharmacokinetic properties and detects EpoR specifically. Therefore, it might become a valuable radiotracer to monitor EpoR status in tumours and support decision-making in anaemia therapy. (orig.)

  2. The effect of erythropoietin on normal and neoplastic cells

    Elliott S; Sinclair AM

    2012-01-01

    Steve Elliott, Angus M SinclairOncology Research, Amgen, Thousand Oaks, CA, USAAbstract: Erythropoietin (Epo) is an essential hormone that binds and activates the Epo receptor (EpoR) resident on the surface of erythroid progenitor cells, thereby promoting erythropoiesis. Recombinant human erythropoietin has been used successfully for over 20 years to treat anemia in millions of patients. In addition to erythropoiesis, Epo has also been reported to have other effects, such as tissue protection...

  3. Erythropoietin Pathway: A Potential Target for the Treatment of Depression.

    Ma, Chongyang; Cheng, Fafeng; Wang, Xueqian; Zhai, Changming; Yue, Wenchao; Lian, Yajun; Wang, Qingguo

    2016-01-01

    During the past decade, accumulating evidence from both clinical and experimental studies has indicated that erythropoietin may have antidepressant effects. In addition to the kidney and liver, many organs have been identified as secretory tissues for erythropoietin, including the brain. Its receptor is expressed in cerebral and spinal cord neurons, the hypothalamus, hippocampus, neocortex, dorsal root ganglia, nerve axons, and Schwann cells. These findings may highlight new functions for erythropoietin, which was originally considered to play a crucial role in the progress of erythroid differentiation. Erythropoietin and its receptor signaling through JAK2 activate multiple downstream signaling pathways including STAT5, PI3K/Akt, NF-κB, and MAPK. These factors may play an important role in inflammation and neuroprogression in the nervous system. This is particularly true for the hippocampus, which is possibly related to learning, memory, neurocognitive deficits and mood alterations. Thus, the influence of erythropoietin on the downstream pathways known to be involved in the treatment of depression makes the erythropoietin-related pathway an attractive target for the development of new therapeutic approaches. Focusing on erythropoietin may help us understand the pathogenic mechanisms of depression and the molecular basis of its treatment. PMID:27164096

  4. Pleiotrophic actions of erythropoietin

    Feldman, Laurie; Sytkowski, Arthur J.

    2003-01-01

    Erythropoietin is the prime regulator of red blood cell production. However, recent evidence suggests that the hormone has multiple effects outside the hematopoietic system. Functional receptors have been identified on a wide variety of normal and malignant cell types, and numerous biologic effects of the hormone on these cells have been observed both in vitro and in vivo. These findings are causing a reassessment of the understanding of erythropoietin physiology. Moreover, there are importan...

  5. Erythropoietin: Current Status

    Bunn, Howard Franklin

    1990-01-01

    Understanding the regulation of red blood cell production has been greatly enhanced by the cloning and expression of the gene for human erythropoietin (Epo) and its receptor. The availability of recombinant human erythropoietin (rhEpo) for administration to patients has ushered in a new era in molecular medicine. Intravenous or subcutaneous administration of rhEpo can reliably cure the anemia of chronic renal failure and may be effective in the treatment of anemias secondary to chronic inflam...

  6. Clinical significance of erythropoietin receptor expression in oral squamous cell carcinoma

    Hypoxic tumors are refractory to radiation and chemotherapy. High expression of biomarkers related to hypoxia in head and neck cancer is associated with a poorer prognosis. The present study aimed to evaluate the clinicopathological significance of erythropoietin receptor (EPOR) expression in oral squamous cell carcinoma (OSCC). The study included 256 patients who underwent primary surgical resection between October 1996 and August 2005 for treatment of OSCC without previous radiotherapy and/or chemotherapy. Clinicopathological information including gender, age, T classification, N classification, and TNM stage was obtained from clinical records and pathology reports. The mRNA and protein expression levels of EPOR in OSCC specimens were evaluated by Q-RT-PCR, Western blotting and immunohistochemistry assays. We found that EPOR were overexpressed in OSCC tissues. The study included 17 women and 239 men with an average age of 50.9 years (range, 26–87 years). The mean follow-up period was 67 months (range, 2–171 months). High EPOR expression was significantly correlated with advanced T classification (p < 0.001), advanced TNM stage (p < 0.001), and positive N classification (p = 0.001). Furthermore, the univariate analysis revealed that patients with high tumor EPOR expression had a lower 5-year overall survival rate (p = 0.0011) and 5-year disease-specific survival rate (p = 0.0017) than patients who had low tumor levels of EPOR. However, the multivariate analysis using Cox’s regression model revealed that only the T and N classifications were independent prognostic factors for the 5-year overall survival and 5-year disease-specific survival rates. High EPOR expression in OSCC is associated with an aggressive tumor behavior and poorer prognosis in the univariate analysis among patients with OSCC. Thus, EPOR expression may serve as a treatment target for OSCC in the future

  7. Chronic Treatment With an Erythropoietin Receptor Ligand Prevents Chronic Kidney Disease-Induced Enlargement of Myocardial Infarct Size.

    Nishizawa, Keitaro; Yano, Toshiyuki; Tanno, Masaya; Miki, Takayuki; Kuno, Atsushi; Tobisawa, Toshiyuki; Ogasawara, Makoto; Muratsubaki, Shingo; Ohno, Kouhei; Ishikawa, Satoko; Miura, Tetsuji

    2016-09-01

    Chronic kidney disease (CKD) is known to increase myocardial infarct size after ischemia/reperfusion. However, a strategy to prevent the CKD-induced myocardial susceptibility to ischemia/reperfusion injury has not been developed. Here, we examined whether epoetin β pegol, a continuous erythropoietin receptor activator (CERA), normalizes myocardial susceptibility to ischemia/reperfusion injury by its effects on protective signaling and metabolomes in CKD. CKD was induced by 5/6 nephrectomy in rats (subtotal nephrectomy, SNx), whereas sham-operated rats served controls (Sham). Infarct size as percentage of area at risk after 20-minutes coronary occlusion/2-hour reperfusion was larger in SNx than in Sham: 60.0±4.0% versus 43.9±2.2%. Administration of CERA (0.6 μg/kg SC every 7 days) for 4 weeks reduced infarct size in SNx (infarct size as percentage of area at risk=36.9±3.9%), although a protective effect was not detected for the acute injection of CERA. Immunoblot analyses revealed that myocardial phospho-Akt-Ser473 levels under baseline conditions and on reperfusion were lower in SNx than in Sham, and CERA restored the Akt phosphorylation on reperfusion. Metabolomic analyses showed that glucose 6-phosphate and glucose 1-phosphate were reduced and malate:aspartate ratio was 1.6-fold higher in SNx than in Sham, suggesting disturbed flux of malate-aspartate shuttle by CKD. The CERA improved the malate:aspartate ratio in SNx to the control level. In H9c2 cells, mitochondrial Akt phosphorylation by insulin-like growth factor-1 was attenuated by malate-aspartate shuttle inhibition. In conclusion, the results suggest that a CERA prevents CKD-induced susceptibility of the myocardium to ischemia/reperfusion injury by restoration of Akt-mediated signaling possibly via normalized malate-aspartate shuttle flux. PMID:27456523

  8. Identification of the receptor for erythropoietin by cross-linking to Friend virus-infected erythroid cells

    Erythropoietin (Epo) is a glycoprotein hormone that regulates erythroid development and interacts with surface receptors on developing erythroid cells. In this laboratory, a cell system with a relatively pure population of erythroid cells that respond to Epo has been developed. Immature erythroid cells are obtained from the spleens of mice infected with the anemia strain of Friend virus. The binding of 125I-labeled Epo (125-Epo) to plasma membranes from these cells was studied in this investigation. 125I-Epo binding reached equilibrium within 20 min at 370C. Twenty percent of the receptors bound 125I-Epo with a K/sub d/ of 0.08 x 10-9 M, while the remaining receptors bound the hormone with a k/sub d/ of 0.6 x 10-9 M. In this study, a receptor for Epo was identified by cross-linking 125I-Epo to the receptor in intact cells and plasma membrane preparations using disuccinimidyl suberate. Polyacrylamide gel electrophoresis revealed two labeled bands of 100 and 85 kDa. The 85-kDa band was more heavily labeled (65%) than the 100-kDa band. Both bands were equally decreased when increasing amounts of unlabeled Epo were included in the binding mixture, indicating a specific interaction of 175I-Epo with the receptor

  9. An amphipathic motif at the transmembrane-cytoplasmic junction prevents autonomous activation of the thrombopoietin receptor.

    Staerk, Judith; Lacout, Catherine; Sato, Takeshi; Smith, Steven O.; Vainchenker, William; Constantinescu, Stefan

    2006-01-01

    Ligand binding to the thrombopoietin receptor (TpoR) is thought to impose a dimeric receptor conformation(s) leading to hematopoietic stem cell renewal, megakaryocyte differentiation, and platelet formation. Unlike other cytokine receptors, such as the erythropoietin receptor, TpoR contains an amphipathic KWQFP motif at the junction between the transmembrane (TM) and cytoplasmic domains. We show here that a mutant TpoR (delta5TpoR), where this sequence was deleted, is constitutively active. I...

  10. Erythropoietin Receptor Positive Circulating Progenitor Cells and Endothelial Progenitor Cells in Patients with Different Stages of Diabetic Retinopathy

    Liu-mei Hu; Guo-xu Xu; Guo-tong XU; Wei-ye Li; Xia Lei; Bo Ma; Yu Zhang; Yan Yan; Ya-lan Wu; Ge-zhi Xu; Wen Ye; Ling Wang

    2011-01-01

    Objective To investigate the possible involvement of erythropoietin (EPO)/erythropoietin receptor(EPOR) system in neovascularization and vascular regeneration in diabetic retinopathy (DR).Methods EPOR positive circulating progenitor cells (CPCs: CD34+) and endothelial progenitor cells (EPCs: CD34+KDR+) were assessed by flow cytometry in type 2 diabetic patients with different stages of DR. The cohort consisted of age- and sex-matched control patients without diabetes (n=7), non-prolif-erative DR (NPDR, n=7), proliferative DR (PDR, n=8), and PDR complicated with diabetic nephropathy (PDR-DN, n=7). Results The numbers of EPOR+ CPCs and EPOR+ EPCs were reduced remarkably in NPDR compared with the control group (both P<0.01), whereas rebounded in PDR and PDR-DN groups in varying degrees. Similar changes were observed in respect of the proportion of EPOR+ CPCs in CPCs (NPDR vs.control, P< 0.01) and that of EPOR+ EPCs in EPCs (NPDR vs. control, P< 0.05). Conclusion Exogenous EPO, mediated via the EPO/EPOR system of EPCs, may alleviate the im-paired vascular regeneration in NPDR, whereas it might aggravate retinal neovascularization in PDR due to a rebound of EPOR+ EPCs associated with ischemia.

  11. Prognostic Impact of Erythropoietin Expression and Erythropoietin Receptor Expression on Locoregional Control and Survival of Patients Irradiated for Stage II/III Non-Small-Cell Lung Cancer

    Purpose: Prognostic factors can guide the physician in selecting the optimal treatment for an individual patient. This study investigates the prognostic value of erythropoietin (EPO) and EPO receptor (EPO-R) expression of tumor cells for locoregional control and survival in non-small-cell lung cancer (NSCLC) patients. Methods and Materials: Fourteen factors were investigated in 62 patients irradiated for stage II/III NSCLC, as follows: age, gender, Karnofsky performance score (KPS), histology, grading, TNM/American Joint Committee on Cancer (AJCC) stage, surgery, chemotherapy, pack years (average number of packages of cigarettes smoked per day multiplied by the number of years smoked), smoking during radiotherapy, hemoglobin levels during radiotherapy, EPO expression, and EPO-R expression. Additionally, patients with tumors expressing both EPO and EPO-R were compared to those expressing either EPO or EPO-R and to those expressing neither EPO nor EPO-R. Results: On univariate analysis, improved locoregional control was associated with AJCC stage II cancer (p 70 (p = 0.08), an N stage of 0 to 1 (p = 0.07), and no EPO-R expression (p = 0.10). On multivariate analysis, AJCC stage II and no EPO expression remained significant. No smoking during radiotherapy was almost significant. On univariate analysis, improved survival was associated with N stage 0 to 1 (p = 0.009), surgery (p = 0.039), hemoglobin levels of ≥12 g/d (p = 0.016), and no EPO expression (p = 0.001). On multivariate analysis, N stage 0 to 1 and no EPO expression maintained significance. Hemoglobin levels of ≥12 g/d were almost significant. On subgroup analyses, patients with tumors expressing both EPO and EPO-R had worse outcomes than those expressing either EPO or EPO-R and those expressing neither EPO nor RPO-R. Conclusions: EPO expression of tumor cells was an independent prognostic factor for locoregional control and survival in patients irradiated for NSCLC. EPO-R expression showed a trend

  12. Effects of Recombinant Erythropoietin on Breast Cancer-Initiating Cells

    Tiffany M. Phillips

    2007-12-01

    Full Text Available BACKGROUND: Cancer anemia causes fatigue and correlates with poor treatment outcome. Erythropoietin has been introduced in an attempt to correct these defects. However, five recent clinical trials reported a negative impact of erythropoietin on survival and/or tumor control, indicating that experimental evaluation of a possible direct effect of erythropoietin on cancer cells is required. Cancer recurrence is thought to rely on the proliferation of cancer initiating cells (CICs. In breast cancer, CICs can be identified by phenotypic markers and their fate is controlled by the Notch pathway. METHODS: In this study, we investigated the effect of erythropoietin on CICs in breast cancer cell lines. Levels of erythropoietin receptor (EpoR, CD24, CD44, Jagged-1 expression, activation of Notch-1 were assessed by flow cytometry. Self-renewing capacity of CICs was investigated in sphere formation assays. RESULTS: EpoR expression was found on the surface of CICs. Recombinant human Epo (rhEpo increased the numbers of CICs and self-renewing capacity in a Notch-dependent fashion by induction of Jagged-1. Inhibitors of the Notch pathway and P13-kinase blocked both effects. CONCLUSIONS: Erythropoietin functionally affects CICs directly. Our observation may explain the negative impact of recombinant Epo on local control and survival of cancer patients with EpoR-positive tumors.

  13. Effects of Erythropoietin on the Bone Microenvironment

    McGee, SJ; Havens, AM; Shiozawa, Y.; Jung, Y.; Taichman, RS

    2011-01-01

    It has well been established that blood and bone share a unique, regulatory relationship with one another, though the specifics of this relationship still remain unanswered. Erythropoietin (Epo) is known primarily for its role as a hematopoietic hormone. However, after the discovery of Epo receptor (Epo-R) outside the hematopoietic tissues, Epo has been avidly studied for its possible non-hematopoietic effects. It has been proposed that Epo interacts with bone both directly, by activating bon...

  14. Role of erythropoietin in the angiogenic activity of bone marrow endothelial cells of MGUS and multiple myeloma patients

    Ferrucci, Arianna; Ria, Roberto; Ruggieri, Simona; Racanelli, Vito; Rao, Luigia; Annese, Tiziana; Nico, Beatrice; Vacca, Angelo; Ribatti, Domenico

    2016-01-01

    Increasing evidences suggest several biological roles for erythropoietin and its receptor (Epo and EpoR), unrelated to erythropoiesis, including angiogenesis. Here, we detected the expression of EpoR in bone marrow-derived endothelial cells from monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) patients (MGECs and MMECs, respectively) and assessed whether Epo plays a role in MGECs- and MMECs-mediated angiogenesis. We show that EpoR is expressed by both MGECs and MMECs even though at a higher level in the first ones. Both EC types respond to rHuEpo in terms of cell proliferation, whereas other responses, including activation of JAK2/STAT5 and PI3K/Akt pathways, cell migration and capillarogenesis are enhanced by Epo in MGECs, but not in MMECs. In addition, the conditioned media of both Epo-treated cells induce a strong angiogenic response in vivo in the chorioallantoic membrane assay, comparable to that of vascular endothelial growth factor (VEGF). Overall, these data highlight the effect of Epo on MGECs- and MMECs-mediated angiogenesis: MGECs are more responsive to Epo treatment than MMECs, probably because over-angiogenic phenotype of MMECs is already activated by their autocrine/paracrine loops occurring in the “angiogenic switch” from MGUS. PMID:26919105

  15. Role of erythropoietin in the angiogenic activity of bone marrow endothelial cells of MGUS and multiple myeloma patients.

    Lamanuzzi, Aurelia; Saltarella, Ilaria; Ferrucci, Arianna; Ria, Roberto; Ruggieri, Simona; Racanelli, Vito; Rao, Luigia; Annese, Tiziana; Nico, Beatrice; Vacca, Angelo; Ribatti, Domenico

    2016-03-22

    Increasing evidences suggest several biological roles for erythropoietin and its receptor (Epo and EpoR), unrelated to erythropoiesis, including angiogenesis. Here, we detected the expression of EpoR in bone marrow-derived endothelial cells from monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) patients (MGECs and MMECs, respectively) and assessed whether Epo plays a role in MGECs- and MMECs-mediated angiogenesis. We show that EpoR is expressed by both MGECs and MMECs even though at a higher level in the first ones. Both EC types respond to rHuEpo in terms of cell proliferation, whereas other responses, including activation of JAK2/STAT5 and PI3K/Akt pathways, cell migration and capillarogenesis are enhanced by Epo in MGECs, but not in MMECs. In addition, the conditioned media of both Epo-treated cells induce a strong angiogenic response in vivo in the chorioallantoic membrane assay, comparable to that of vascular endothelial growth factor (VEGF). Overall, these data highlight the effect of Epo on MGECs- and MMECs-mediated angiogenesis: MGECs are more responsive to Epo treatment than MMECs, probably because over-angiogenic phenotype of MMECs is already activated by their autocrine/paracrine loops occurring in the "angiogenic switch" from MGUS. PMID:26919105

  16. Transferrin receptor number, synthesis, and endocytosis during erythropoietin-induced maturation of Friend virus-infected erythroid cells

    Erythropoietin (EP) responsive Friend virus-infected erythroid cells had 200,000 steady-state binding sites for transferrin at 370C when isolated from the spleens of Friend virus-infected mice. Upon culture of these cells with EP, the synthesis of transferrin receptors increased 4- to 7-fold and the number of transferrin-binding sites per cell doubled after 24 h. However, the rate of uptake of 59Fe from transferrin remained constant at approximately 35,000 atoms of 59Fe per minute per cell during this period in culture. The amount of 125I-transferrin internalized during the steady-state binding did not change during this culture period while the transferrin bound to the surface increased 3-fold. At all stages of erythroid maturation, the maximum rate of endocytosis was determined to be 18,000 molecules of transferrin per minute per cell, and the interval that 125I-transferrin remains in the interior of the cell was calculated to be 6.9 min. After 48 h of culture with EP, the number of steady-state transferrin-binding sites was reduced in part due to the sequestration of surface receptors within the cell. The uptake of iron from transferrin was limited by the level of endocytosis of transferrin during the initial phase of culture and the number of transferrin receptors at the cell surface during the latter stages of erythroid maturation of these cells

  17. Effects of erythropoietin on memory-relevant neurocircuitry activity and recall in mood disorders

    Miskowiak, K W; Macoveanu, J; Vinberg, M;

    2016-01-01

    OBJECTIVE: Erythropoietin (EPO) improves verbal memory and reverses subfield hippocampal volume loss across depression and bipolar disorder (BD). This study aimed to investigate with functional magnetic resonance imaging (fMRI) whether these effects were accompanied by functional changes in memory......MRI at 3T, mood ratings, and blood tests at baseline and week 14. During fMRI, participants performed a picture encoding task followed by postscan recall. RESULTS: Sixty-two patients had complete data (EPO: N = 32, saline: N = 30). EPO improved picture recall and increased encoding-related activity in...... cohort. The effects of EPO were not correlated with change in mood, red blood cells, blood pressure, or medication. CONCLUSION: The findings highlight enhanced encoding-related dlPFC and temporo-parietal activity as key neuronal underpinnings of EPO-associated memory improvement....

  18. Research Advances in Expression and Function of Erythropoietin and Erythropoietin Receptor in Tumors%促红细胞生成素及其受体在肿瘤中的表达及作用研究进展

    孔令英

    2011-01-01

    促红细胞生成素(EPO)最早被发现只在胎肝及成人肾脏中合成,可以促进红系集落形成单位的有丝分裂和增殖,并向形态可识别的前体细胞分化.研究发现,EPO及其受体(EPO-R)在多种不同非造血器官及组织中表达,并发挥组织保护、免疫调节、促进血管增生等作用.临床上已经成功地将重组的促红细胞生成素用于治疗肿瘤相关贫血等疾病.最新多项研究发现,在多种恶性肿瘤组织细胞中存在EPO及EPO-R的表达.%Erythropoietin was firstly found to be synthesized by fetal hepatocytes and human kidney, and it could stimulate the mitosis, proliferation, and differentiation into recognizable blood precursors of colonyforming unit-erythrocyte. Recent researches have shown EPO and its receptor( erythropoietin receptor, EPOR )express in many nonhematopoietic organs and multiple tissues, and exert tissue-protective,immunoregulatory and angiogenic effects in human body. Recombinant human erythropoietin( rh-EPO )has been successfully used in clinic to treat malignancy-associated anemia and other diseases. A series of studies have reported that EPO and EPO-R also express in various tumor cells.

  19. The gene for erythropoietin receptor is expressed in multipotential hematopoietic and embryonal stem cells: evidence for differentiation stage-specific regulation.

    Heberlein, C; Fischer, K D; Stoffel, M; Nowock, J; Ford, A.; Tessmer, U.; Stocking, C

    1992-01-01

    The principal regulator of erythropoiesis is the glycoprotein erythropoietin, which interacts with a specific cell surface receptor (EpoR). A study aimed at analyzing EpoR gene regulation has shown that both pluripotent embryonal stem cells and early multipotent hematopoietic cells express EpoR transcripts. Commitment to nonerythroid lineages (e.g., macrophage or lymphocytic) results in the shutdown of EpoR gene expression, whereas commitment to the erythroid lineage is concurrent with or fol...

  20. Functional regions of the mouse thrombopoietin receptor cytoplasmic domain: evidence for a critical region which is involved in differentiation and can be complemented by erythropoietin.

    Porteu, F; Rouyez, M C; Cocault, L; Bénit, L; Charon, M; Picard, F; Gisselbrecht, S; Souyri, M; Dusanter-Fourt, I

    1996-01-01

    Thrombopoietin (TPO) is the major regulator of growth and differentiation of megakaryocytes. To identify functionally important regions in the cytoplasmic domain of the TPO receptor, mpl, we introduced wild-type mpl and deletion mutants of murine mpl into the granulocyte-macrophage colony-stimulating factor (GM-CSF)- or erythropoietin (EPO)-dependent human cell line UT7. TPO induced differentiation of UT7-Wtmpl cells, not parental UT7 cells, along the megakaryocytic lineage, as evidenced by d...

  1. Biology of erythropoietin.

    Lacombe, C; Mayeux, P

    1998-08-01

    Erythropoietin (Epo) controls the proliferation, differentiation and survival of the erythroid progenitors. This cytokine was cloned in 1985 and rapidly became used for treatment of anemia of renal failure, opening the way to the first clinical trials of a hematopoietic growth factor. The clonage of one chain of the Epo receptor followed in 1989, thereby opening the research on intracellular signal transduction induced by Epo. Epo is synthesized mainly by the kidney and the liver and sequences required for tissue-specific expression have been localized in the Epo gene. A 3'enhancer is responsible for hypoxia-inducible Epo gene expression. HIF-1 alpha and beta proteins bind to this enhancer. Gene regulation by hypoxia is widespread in many cells and involves numerous genes in addition to the Epo gene. The Epo receptor belongs to the cytokine receptor family and includes a p66 chain which is dimerized upon Epo activation; two accessory proteins defined by cross-linking remain to be characterized. Epo binding induces the stimulation of Jak2 tyrosine kinase. Jak2 activation leads to the tyrosine phosphorylation of several proteins including the Epo receptor itself. As a result, different intracellular pathways are activated: Ras/MAP kinase, phosphatidylinositol 3-kinase and STAT transcription factors. However, the exact mechanisms by which the proliferation and/or the differentiation of erythroid cells are regulated after Epo stimulation are not known. Furthermore, target disruption of both Epo and Epo receptor showed that Epo was not involved in the commitment of the erythroid lineage and seemed to act mainly as a survival factor. PMID:9793257

  2. Recombinant human erythropoietin reduces plasminogen activator inhibitor and ameliorates pro-inflammatory responses following trauma

    M Mojtahedzadeh

    2011-05-01

    Full Text Available "n  "n Background and the purpose of the study: Besides its hematopoietic effects, erythropoietin (EPO by mobilization of iron and modulation of some inflammatory cytokines has antioxidant and anti-inflammatory properties. The purpose of this study was to evaluate these effects of erythropoietin and its impact on organ function in traumatized patients. "n Methods: Twenty-six ICU-admitted traumatized patients within 24 hrs after trauma were randomly assigned to the EPO (received EPO, 300 units/Kg/day and Control (not received EPO groups. The inflammatory biomarkers including Tumor Necrosis Factor alpha (TNF-α, Interleukin 1 (IL-1, Plasminogen Activator Inhibitor 1 (PAI-1 and Nitrotyrosine were recorded at the admission, 3, 6 and 9 days thereafter. Acute Physiology and Chronic Health Evaluation (APACHE II and Sequential Organ Failure Assessment (SOFA scores were also recorded. "n Results: Among 12 patients (EPO group TNF-α level at the day of 9 (P=0.046, and within EPO group at the days of 3 (P=0.026 ameliorate, 6 (P=0.016, and 9 (P=0.052 were significantly lowered. Level of IL-1 and PAI-1 decreased significantly at days of 3, 6 and 9 post intervention. Also there were significant differences between two groups in the SOFA score during three measured time intervals (the first, third and seventh days. "n Conclusion: From the results of this study it seems that injection of erythrocyte stimulating agent is well tolerated and inhibits the inflammatory response and oxidative stress following trauma.

  3. Characterization of a monoclonal antibody to human erythropoietin.

    Weiss, T L; Kavinsky, C J; Goldwasser, E

    1982-01-01

    Hybrid cells that synthesize a monospecific antibody directed toward erythropoietin have been produced by the fusion of mouse plasmacytoma cells with spleen cells from rats immunized against human erythropoietin. The antibody binds the alpha and beta forms and the asialo alpha form of erythropoietin to the same extent. It is an immunoglobulin of the IgG class and binds only erythropoietin in an impure preparation of the hormone. Biologically active unlabeled erythropoietin competes with biolo...

  4. Erythropoietin Activates Mitochondrial Biogenesis and Couples Red Cell Mass to Mitochondrial Mass in the Heart

    RATIONALE: Erythropoietin (EPO) is often administered to cardiac patients with anemia, particularly from chronic kidney disease, and stimulation of erythropoiesis may stabilize left ventricular and renal function by recruiting protective effects beyond the correction of anemia. O...

  5. Identification of Cell Type-Specific Differences in Erythropoietin Receptor Signaling in Primary Erythroid and Lung Cancer Cells

    Salopiata, Florian; Depner, Sofia; Wäsch, Marvin; Böhm, Martin E.; Mücke, Oliver; Plass, Christoph; Lehmann, Wolf D.; Kreutz, Clemens; Timmer, Jens; Klingmüller, Ursula

    2016-01-01

    Lung cancer, with its most prevalent form non-small-cell lung carcinoma (NSCLC), is one of the leading causes of cancer-related deaths worldwide, and is commonly treated with chemotherapeutic drugs such as cisplatin. Lung cancer patients frequently suffer from chemotherapy-induced anemia, which can be treated with erythropoietin (EPO). However, studies have indicated that EPO not only promotes erythropoiesis in hematopoietic cells, but may also enhance survival of NSCLC cells. Here, we verified that the NSCLC cell line H838 expresses functional erythropoietin receptors (EPOR) and that treatment with EPO reduces cisplatin-induced apoptosis. To pinpoint differences in EPO-induced survival signaling in erythroid progenitor cells (CFU-E, colony forming unit-erythroid) and H838 cells, we combined mathematical modeling with a method for feature selection, the L1 regularization. Utilizing an example model and simulated data, we demonstrated that this approach enables the accurate identification and quantification of cell type-specific parameters. We applied our strategy to quantitative time-resolved data of EPO-induced JAK/STAT signaling generated by quantitative immunoblotting, mass spectrometry and quantitative real-time PCR (qRT-PCR) in CFU-E and H838 cells as well as H838 cells overexpressing human EPOR (H838-HA-hEPOR). The established parsimonious mathematical model was able to simultaneously describe the data sets of CFU-E, H838 and H838-HA-hEPOR cells. Seven cell type-specific parameters were identified that included for example parameters for nuclear translocation of STAT5 and target gene induction. Cell type-specific differences in target gene induction were experimentally validated by qRT-PCR experiments. The systematic identification of pathway differences and sensitivities of EPOR signaling in CFU-E and H838 cells revealed potential targets for intervention to selectively inhibit EPO-induced signaling in the tumor cells but leave the responses in erythroid

  6. Identification of Cell Type-Specific Differences in Erythropoietin Receptor Signaling in Primary Erythroid and Lung Cancer Cells.

    Merkle, Ruth; Steiert, Bernhard; Salopiata, Florian; Depner, Sofia; Raue, Andreas; Iwamoto, Nao; Schelker, Max; Hass, Helge; Wäsch, Marvin; Böhm, Martin E; Mücke, Oliver; Lipka, Daniel B; Plass, Christoph; Lehmann, Wolf D; Kreutz, Clemens; Timmer, Jens; Schilling, Marcel; Klingmüller, Ursula

    2016-08-01

    Lung cancer, with its most prevalent form non-small-cell lung carcinoma (NSCLC), is one of the leading causes of cancer-related deaths worldwide, and is commonly treated with chemotherapeutic drugs such as cisplatin. Lung cancer patients frequently suffer from chemotherapy-induced anemia, which can be treated with erythropoietin (EPO). However, studies have indicated that EPO not only promotes erythropoiesis in hematopoietic cells, but may also enhance survival of NSCLC cells. Here, we verified that the NSCLC cell line H838 expresses functional erythropoietin receptors (EPOR) and that treatment with EPO reduces cisplatin-induced apoptosis. To pinpoint differences in EPO-induced survival signaling in erythroid progenitor cells (CFU-E, colony forming unit-erythroid) and H838 cells, we combined mathematical modeling with a method for feature selection, the L1 regularization. Utilizing an example model and simulated data, we demonstrated that this approach enables the accurate identification and quantification of cell type-specific parameters. We applied our strategy to quantitative time-resolved data of EPO-induced JAK/STAT signaling generated by quantitative immunoblotting, mass spectrometry and quantitative real-time PCR (qRT-PCR) in CFU-E and H838 cells as well as H838 cells overexpressing human EPOR (H838-HA-hEPOR). The established parsimonious mathematical model was able to simultaneously describe the data sets of CFU-E, H838 and H838-HA-hEPOR cells. Seven cell type-specific parameters were identified that included for example parameters for nuclear translocation of STAT5 and target gene induction. Cell type-specific differences in target gene induction were experimentally validated by qRT-PCR experiments. The systematic identification of pathway differences and sensitivities of EPOR signaling in CFU-E and H838 cells revealed potential targets for intervention to selectively inhibit EPO-induced signaling in the tumor cells but leave the responses in erythroid

  7. Comparison of real time RT-PCR and flow cytometry methods for evaluation of biological activity of recombinant human erythropoietin

    Sepehrizadeh Z

    2008-05-01

    Full Text Available Background: Evaluation of bioactivity of recombinant erythropoietin is essential for pharmaceutical industry, quality control authorities and researchers. The purpose of this study was to compare real time RT-PCR and flow cytometry for the assay of biological activity of recombinant erythropoietin. Methods: Three concentrations of recombinant erythropoietin BRP (80, 40 and 20 IU/ml were injected subcutaneously to mice. After 4 days the blood was collected and used for reticulocyte counts by flow cytometry and also for the RNA extraction. Real time RT-PCR amplification was carried out for β-globin. Results and conclusion: There was a significant correlation between the total RNA amounts (R2= 0.9995, relative quantity of β-globin mRNA (R2= 0.984 and reticulocyte counts (R2= 0.9742 with rhEpo concentrations. Total RNA and quantitative RT-PCR showed significant dose dependent results as well the reticulocyte counts by flow cytometry for the biological activity assay of rhEpo and so these methods could be considered as alternatives for flow cytometry.

  8. Nonclinical evaluation of the potential for mast cell activation by an erythropoietin analog.

    Weaver, James L; Boyne, Michael; Pang, Eric; Chimalakonda, Krishna; Howard, Kristina E

    2015-09-15

    The erythropoietin analog peginesatide was withdrawn from marketing due to unexpected severe anaphylactic reactions associated with administration of the multi-use formulation. The adverse events occurred rapidly following the first ever administration of the drug with most affected patients becoming symptomatic in less than 30min. This is most consistent with an anaphylactoid reaction due to direct activation of mast cells. Laboratory evaluation was undertaken using rat peritoneal mast cells as the model system. Initial studies showed that high concentrations of the formulated drug as well as formulated vehicle alone could cause mast cell degranulation as measured by histamine release. The purified active drug was not able to cause histamine release whereas the vehicle filtrate and lab created drug vehicle were equally potent at causing histamine release. Individual formulations of vehicle leaving one component out showed that histamine release was due to phenol. Dose response studies with phenol showed a very sharp dose response curve that was similar in three buffer systems. Cellular analysis by flow cytometry showed that the histamine release was not due to cell death, and that changes in light scatter parameters consistent with degranulation were rapidly observed. Limited testing with primary human mast cells showed a similar dose response of histamine release with exposure to phenol. To provide in vivo confirmation, rats were injected with vehicle formulated with various concentrations of phenol via a jugular vein cannula. Significant release of histamine was detected in blood samples taken 2min after dosing at the highest concentrations tested. PMID:26079829

  9. Erythropoietin Modulates Cerebral and Serum Degradation Products from Excess Calpain Activation following Prenatal Hypoxia-Ischemia.

    Jantzie, Lauren L; Winer, Jesse L; Corbett, Christopher J; Robinson, Shenandoah

    2016-01-01

    Preterm infants suffer central nervous system (CNS) injury from hypoxia-ischemia and inflammation - termed encephalopathy of prematurity. Mature CNS injury activates caspase and calpain proteases. Erythropoietin (EPO) limits apoptosis mediated by activated caspases, but its role in modulating calpain activation has not yet been investigated extensively following injury to the developing CNS. We hypothesized that excess calpain activation degrades developmentally regulated molecules essential for CNS circuit formation, myelination and axon integrity, including neuronal potassium-chloride co-transporter (KCC2), myelin basic protein (MBP) and phosphorylated neurofilament (pNF), respectively. Further, we predicted that post-injury EPO treatment could mitigate CNS calpain-mediated degradation. Using prenatal transient systemic hypoxia-ischemia (TSHI) in rats to mimic CNS injury from extreme preterm birth, and postnatal EPO treatment with a clinically relevant dosing regimen, we found sustained postnatal excess cortical calpain activation following prenatal TSHI, as shown by the cleavage of alpha II-spectrin (αII-spectrin) into 145-kDa αII-spectrin degradation products (αII-SDPs) and p35 into p25. Postnatal expression of the endogenous calpain inhibitor calpastatin was also reduced following prenatal TSHI. Calpain substrate expression following TSHI, including cortical KCC2, MBP and NF, was modulated by postnatal EPO treatment. Calpain activation was reflected in serum levels of αII-SDPs and KCC2 fragments, and notably, EPO treatment also modulated KCC2 fragment levels. Together, these data indicate that excess calpain activity contributes to the pathogenesis of encephalopathy of prematurity. Serum biomarkers of calpain activation may detect ongoing cerebral injury and responsiveness to EPO or similar neuroprotective strategies. PMID:26551007

  10. Erythropoietin blockade inhibits the induction of tumor angiogenesis and progression.

    Matthew E Hardee

    Full Text Available BACKGROUND: The induction of tumor angiogenesis, a pathologic process critical for tumor progression, is mediated by multiple regulatory factors released by tumor and host cells. We investigated the role of the hematopoietic cytokine erythropoietin as an angiogenic factor that modulates tumor progression. METHODOLOGY/PRINCIPAL FINDINGS: Fluorescently-labeled rodent mammary carcinoma cells were injected into dorsal skin-fold window chambers in mice, an angiogenesis model that allows direct, non-invasive, serial visualization and real-time assessment of tumor cells and neovascularization simultaneously using intravital microscopy and computerized image analysis during the initial stages of tumorigenesis. Erythropoietin or its antagonist proteins were co-injected with tumor cells into window chambers. In vivo growth of cells engineered to stably express a constitutively active erythropoietin receptor EPOR-R129C or the erythropoietin antagonist R103A-EPO were analyzed in window chambers and in the mammary fat pads of athymic nude mice. Co-injection of erythropoietin with tumor cells or expression of EPOR-R129C in tumor cells significantly stimulated tumor neovascularization and growth in window chambers. Co-injection of erythropoietin antagonist proteins (soluble EPOR or anti-EPO antibody with tumor cells or stable expression of antagonist R103A-EPO protein secreted from tumor cells inhibited angiogenesis and impaired tumor growth. In orthotopic tumor xenograft studies, EPOR-R129C expression significantly promoted tumor growth associated with increased expression of Ki67 proliferation antigen, enhanced microvessel density, decreased tumor hypoxia, and increased phosphorylation of extracellular-regulated kinases ERK1/2. R103A-EPO antagonist expression in mammary carcinoma cells was associated with near-complete disruption of primary tumor formation in the mammary fat pad. CONCLUSIONS/SIGNIFICANCE: These data indicate that erythropoietin is an

  11. Nonclinical evaluation of the potential for mast cell activation by an erythropoietin analog

    Weaver, James L., E-mail: James.Weaver@fda.hhs.gov [Division of Applied Regulatory Science, OCP/OTS/CDER/FDA, Silver Spring, MD (United States); Boyne, Michael, E-mail: mboyne@biotechlogic.com [Division of Pharmaceutical Analysis, OTR/OPQ/CDER/FDA, Silver Spring, MD (United States); Pang, Eric, E-mail: Eric.Pang@fda.hhs.gov [Division of Applied Regulatory Science, OCP/OTS/CDER/FDA, Silver Spring, MD (United States); Chimalakonda, Krishna, E-mail: Krishna.Chimalakonda@fda.hhs.gov [Division of Applied Regulatory Science, OCP/OTS/CDER/FDA, Silver Spring, MD (United States); Howard, Kristina E., E-mail: Kristina.Howard@fda.hhs.gov [Division of Applied Regulatory Science, OCP/OTS/CDER/FDA, Silver Spring, MD (United States)

    2015-09-15

    The erythropoietin analog peginesatide was withdrawn from marketing due to unexpected severe anaphylactic reactions associated with administration of the multi-use formulation. The adverse events occurred rapidly following the first ever administration of the drug with most affected patients becoming symptomatic in less than 30 min. This is most consistent with an anaphylactoid reaction due to direct activation of mast cells. Laboratory evaluation was undertaken using rat peritoneal mast cells as the model system. Initial studies showed that high concentrations of the formulated drug as well as formulated vehicle alone could cause mast cell degranulation as measured by histamine release. The purified active drug was not able to cause histamine release whereas the vehicle filtrate and lab created drug vehicle were equally potent at causing histamine release. Individual formulations of vehicle leaving one component out showed that histamine release was due to phenol. Dose response studies with phenol showed a very sharp dose response curve that was similar in three buffer systems. Cellular analysis by flow cytometry showed that the histamine release was not due to cell death, and that changes in light scatter parameters consistent with degranulation were rapidly observed. Limited testing with primary human mast cells showed a similar dose response of histamine release with exposure to phenol. To provide in vivo confirmation, rats were injected with vehicle formulated with various concentrations of phenol via a jugular vein cannula. Significant release of histamine was detected in blood samples taken 2 min after dosing at the highest concentrations tested. - Highlights: • Peginesatide caused severe anaphylactoid reactions in 0.2% of patients. • Both formulated drug and vehicle cause degranulation of rat mast cells. • Phenol was identified as the vehicle component causing degranulation. • Human mast cells show similar dose response to phenol as rat mast cells

  12. Human recombinant erythropoietin promotes differentiation of murine megakaryocytes in vitro.

    Ishibashi, T.; Koziol, J A; Burstein, S A

    1987-01-01

    To determine if erythropoietin affects megakaryocytopoiesis, we measured acetylcholinesterase (AchE) activity, a marker of the murine megakaryocytic lineage, after the addition of human recombinant erythropoietin to serumless murine bone marrow cultures. Erythropoietin increased AchE activity substantially. Moreover, when the hormone was added to serumless cultures of 426 isolated single megakaryocytes derived from megakaryocytic colonies, erythropoietin induced a significant increase in the ...

  13. The glucocorticoid receptor cooperates with the erythropoietin receptor and c-Kit to enhance and sustain proliferation of erythroid progenitors in vitro

    W. Zauner; G. Mellitzer; P. Steinlein (Peter); G. Fritsch; K. Huber; H. Beug (Hartmut); B. Löwenberg (Bob); M.M. von Lindern (Marieke)

    1999-01-01

    textabstractAlthough erythropoietin (Epo) is essential for the production of mature red blood cells, the cooperation with other factors is required for a proper balance between progenitor proliferation and differentiation. In avian erythroid progenitors, steroid hormone

  14. Enhanced erythropoietin and suppression of γ-glutamyl trans-peptidase (GGT) activity in murine lymphoma following administration of vanadium

    Administration of vanadium as ammonium mono-vanadate (0.005 μg/0.1 ml/mouse/day) was found to reduce the tumor cell proliferation in the host mice bearing Dalton's lymphoma. The high activity of γ-glutamyl trans-peptidase (CCT), a neoplastic marker, was seen in the host cells bearing lymphoma. Vanadium effectively prevented an increase in activity of γ-glutamyl trans-peptidase and maintained a sustained low activity of this enzyme. In addition, an improvement of the hematological aspects of the mice and almost fourfold elevation of erythropoietin (Epo) was obtained following vanadium treatment. This in Epo activity may play a vital role in regulating the growth of cellular neoplasia. The present study further confirms the anti-tumorigenic potential of vanadium in the control of tumor progression in lymphoma via modulating several factors involving erythropoiesis and may emerge as a new chemo-preventive agent for the future. (author)

  15. Erythropoietin receptor in human skeletal muscle and the effects of acute and long-term injections with recombinant human erythropoietin on the skeletal muscle

    Lundby, Carsten; Hellsten, Ylva; Jensen, Mie B. F.;

    2008-01-01

    potential effects of Epo in human skeletal muscle, two separate studies were conducted: one to study the acute effects of a single Epo injection on skeletal muscle gene expression and plasma hormones and another to study the effects of long-term (14 wk) Epo treatment on skeletal muscle structure. Subjects...... (n = 11) received a single Epo injection of 15,000 IU (double blinded, cross over, placebo). A single Epo injection reduced myoglobin and increased transferrin receptor and MRF-4 mRNA content within 10 h after injection. Plasma hormones remained unaltered. Capillarization and fiber hypertrophy was...

  16. Erythropoietin during hypoglycaemia in type 1 diabetes

    Kristensen, Peter Lommer; Høi-Hansen, Thomas; Olsen, Niels Vidiendal;

    2009-01-01

    AIMS: Preservation of cognitive function during hypoglycaemic episodes is crucial for patients with insulin-treated diabetes to avoid severe hypoglycaemic events. Erythropoietin has neuroprotective potential. However, the role of erythropoietin during hypoglycaemia is unclear. The aim of the study...... was to explore plasma erythropoietin response to hypoglycaemia and the relationship to basal renin-angiotensin system (RAS) activity and cognitive function. METHODS: We performed a single-blinded, controlled, cross-over study with induced hypoglycaemia or maintained glycaemic level. Nine patients with...... type 1 diabetes with high and nine with low activity in RAS were studied. Hypoglycaemia was induced using a standardized insulin-infusion. RESULTS: Overall, erythropoietin concentrations increased during hypoglycaemia. In the high RAS group erythropoietin rose 29% (p=0.032) whereas no significant...

  17. [Overview of erythropoietin].

    Lacombe, C; Mayeux, P; Casadevall, N

    1991-01-01

    Erythropoietin (Epo) is a glycoprotein that promotes the proliferation and differentiation of erythrocyte precursors. The major site of Epo production is the kidney and the liver is the main extra renal site of Epo production. Epo producing cells were identified by in situ hybridization, in the kidney, they are peritubular cells, most likely endothelial cells of the cortex and outer medulla; in the liver, they are mainly hepatocytes. The Epo secretion is stimulated by hypoxia, which is detected by an oxygen sensor. The Epo receptor is a multimeric protein, one chain which binds Epo has been cloned. However the structure of the Epo receptor is still puzzling, and one or more accessory chains remain to be identified. Since the clonage of the Epo gene, recombinant Epo has been available and allowed the treatment of patients with renal diseases with a constant efficacy. PMID:1662784

  18. Erythropoietin use and abuse.

    John, M Joseph; Jaison, Vineeth; Jain, Kunal; Kakkar, Naveen; Jacob, Jubbin J

    2012-03-01

    Recombinant human erythropoietin (rhEPO) is arguably the most successful therapeutic application of recombinant DNA technology till date. It was isolated in 1977 and the gene decoded in 1985. Since then, it has found varied applications, especially in stimulating erythropoiesis in anemia due to chronic conditions like renal failure, myelodysplasia, infections like HIV, in prematurity, and in reducing peri-operative blood transfusions. The discovery of erythropoietin receptor (EPO-R) and its presence in non-erythroid cells has led to several areas of research. Various types of rhEPO are commercially available today with different dosage schedules and modes of delivery. Their efficacy in stimulating erythropoiesis is dose dependent and differs according to the patient's disease and nutritional status. EPO should be used carefully according to guidelines as unsolicited use can result in serious adverse effects. Because of its capacity to improve oxygenation, it has been abused by athletes participating in endurance sports and detecting this has proved to be a challenge. PMID:22470858

  19. Erythropoietin use and abuse

    M Joseph John

    2012-01-01

    Full Text Available Recombinant human erythropoietin (rhEPO is arguably the most successful therapeutic application of recombinant DNA technology till date. It was isolated in 1977 and the gene decoded in 1985. Since then, it has found varied applications, especially in stimulating erythropoiesis in anemia due to chronic conditions like renal failure, myelodysplasia, infections like HIV, in prematurity, and in reducing peri-operative blood transfusions. The discovery of erythropoietin receptor (EPO-R and its presence in non-erythroid cells has led to several areas of research. Various types of rhEPO are commercially available today with different dosage schedules and modes of delivery. Their efficacy in stimulating erythropoiesis is dose dependent and differs according to the patient′s disease and nutritional status. EPO should be used carefully according to guidelines as unsolicited use can result in serious adverse effects. Because of its capacity to improve oxygenation, it has been abused by athletes participating in endurance sports and detecting this has proved to be a challenge.

  20. Erythropoietin and radiotherapy; Erythropoietine et radiotherapie

    Le Fur, E.; Albarghach, M.N.; Pradier, O. [CHU de Morvan, Dept. de radiotherapie, 29 - Brest (France)

    2010-01-15

    Erythropoietin (E.P.O.) is a glycoprotein hormone. This hormone is a growth factor for red blood cells precursors in the bone marrow. The decrease of oxygen partial pressure, a reduced number of erythrocytes caused by bleeding or excessive destruction, or increased tissues oxygen requirements lead to increased secretion of E.P.O.. Its action takes place on bone marrow erythroblastic cells through specific receptors. E.P.O. stimulates the proliferation of red cell precursors stem cells in the bone marrow, thus increasing their production in one to two weeks. The effectiveness of E.P.O. at increasing haemoglobin and improving patients quality of life has been demonstrated by several studies. However, its use in radiotherapy remains controversial. While tumour hypoxia caused by anaemia is a factor of radio resistance and thus a source of local failure, tumour expression of E.P.O. receptors presents a significant risk for tumour progression and neo-angiogenesis, which would be increased during the administration of E.P.O.. The purpose of this article is to answer the question: is there a place for E.P.O. in combination with radiotherapy in the management of cancer?

  1. Dimer formation of receptor activator of nuclear factor κB induces incomplete osteoclast formation

    Receptor activator of nuclear factor κB-ligand (RANKL) transduces a differentiation signal appropriate to osteoclasts likely through induction a receptor homotrimer; however, biological importance of RANK-trimerizarion is unknown. To address the signaling mechanism of the RANK receptor, we analyzed the effect of two different types of homodimer inducers RANK-TM-FKBP36v and hEpoR-RANK-TM on osteoclastogenesis. Dimerizing component FKBP36v or extracellular portion of human erythropoietin receptor (hEpoR) was fused to RANK lacking the extracellular domain, and the dimerization of this fusion protein was induced by addition of the chemical inducer of dimerization AP20187 or erythropoietin, respectively. Such treatment resulted in induction of TRAP-activity, a marker of osteoclast in a dose dependent manner, with an efficiency equivalent to that of induction by RANKL. However, dimerized-RANK-induced osteoclasts showed relatively low levels of multinucleation, pit forming activity, and expression of calcitonin receptor and cathepsin K, compared with osteoclasts which were induced in the presence of RANKL. As expression of nuclear factor of activated T cells 1 (NFATc1) was also reduced in dimerized-RANK-induced osteoclasts, RANK oligomerization by RANKL is a critical event to generate fully matured osteoclasts through upregulation of NFATc1

  2. Sexual dimorphism of erythropoietin-degrading activity in mouse submaxillary gland extracts

    Tam, R.C.; Bedwell, J.; Cotes, P.M.; Reed, P.J.

    1989-02-01

    In the course of investigation of submaxillary gland (SG) extracts from mice as a possible source of extra-renal erythropoietin (EPO) we have extended our previous studies of the degradation of EPO added to SG and kidney extracts. The discrepancy between estimates of EPO obtained with two radioimmunoassays (RIAs) differing only in time of incubation with /sup 125/I-labeled recombinant human EPO (r-HuEPO) (20 h and 72 h) has been used as an indicator of tracer degradation occurring during the RIA incubation. Degradation of /sup 125/I-labeled r-HuEPO by male mouse SG extracts was not prevented by addition of inhibitors of monodeiodinases or proteolytic enzymes. Degradation of added /sup 125/I-labeled r-HuEPO was monitored using gel filtration fast protein liquid chromatography. SG extracts from male and androgen-treated female mice both degraded tracer r-HuEPO to a greater extent than extracts from female mice. Tracer degradation increased with time and tissue concentration and could give rise to invalid estimates of EPO in SG extracts by RIA. In contrast, none of the kidney extracts degraded r-HuEPO. Recovery of mouse serum EPO added to and incubated with male mouse SG or kidney extracts was 13% and 93%, respectively, estimated by RIA under conditions that excluded degradation of the RIA tracer antigen.

  3. Coexpression of Kit and the receptors for erythropoietin, interleukin 6 and GM-CSF on hemopoietic cells

    M.O. de Jong (Marg); Y. Westerman (Yvonne); G. Wagemaker (Gerard); A.W. Wognum (Albert)

    1997-01-01

    textabstractThe detection of functional growth factor (GF) receptors on subpopulations of hemopoietic cells may provide a further dissection of immature cell subsets. Since little information is available about coexpression of different GF receptors at the level of sing

  4. Erythropoietin Protects Rat Brain Injury from Carbon Monoxide Poisoning by Inhibiting Toll-Like Receptor 4/NF-kappa B-Dependent Inflammatory Responses.

    Pang, Li; Zhang, Nan; Dong, Ning; Wang, Da-Wei; Xu, Da-Hai; Zhang, Ping; Meng, Xiang-Wei

    2016-04-01

    Inflammatory responses play critical roles in carbon monoxide (CO) poisoning-induced cerebral injury. The present study investigated whether erythropoietin (EPO) modulates the toll-like receptor 4 (TLR4) and nuclear factor-kappa B (NF-κB) inflammatory signaling pathways in brain injury after acute CO poisoning. EPO (2500 and 5000 U/kg) was injected subcutaneously twice a day after acute CO poisoning for 2 days. At 48 h after treatment, the expression levels of TLR4 and NF-κB as well as the levels of inflammatory cytokines in the hippocampal tissues were measured. Our results showed that CO poisoning induced a significant upregulation of TLR4, NF-κB, and inflammatory cytokines in the injured rat hippocampal tissues. Treatment with EPO remarkably suppressed the gene and protein expression levels of TLR4 and NF-κB, as well as the concentrations of TNF-α, IL-1β, and IL-6 in the hippocampal tissues. EPO treatment ameliorated CO poisoning-induced histological edema and neuronal necrosis. These results suggested that EPO protected against CO poisoning-induced brain damage by inhibiting the TLR4-NF-κB inflammatory signaling pathway. PMID:26521252

  5. Site-specific antibodies to human erythropoietin directed toward the NH2-terminal region.

    Sue, J M; Sytkowski, A. J.

    1983-01-01

    Site-specific antibodies to human erythropoietin have been raised in rabbits immunized with a synthetic polypeptide composed of the putative 26 NH2-terminal amino acids of the hormone. The immunogenic peptide was coupled to bovine serum albumin. Antibodies specific for peptide were detected by enzyme-linked immunosorbent assay. They immunoprecipitated both highly purified 125I-labeled erythropoietin and biologically active erythropoietin. The immunoprecipitation of 125I-labeled erythropoietin...

  6. Erythropoietin activates two distinct signaling pathways required for the initiation and the elongation of c-myc

    Chen, C.; Sytkowski, A. J.

    2001-01-01

    Erythropoietin (Epo) stimulation of erythroid cells results in the activation of several kinases and a rapid induction of c-myc expression. Protein kinase C is necessary for Epo up-regulation of c-myc by promoting elongation at the 3'-end of exon 1. PKCepsilon mediates this signal. We now show that Epo triggers two signaling pathways to c-myc. Epo rapidly up-regulated Myc protein in BaF3-EpoR cells. The phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 blocked Myc up-regulation in a concentration-dependent manner but had no effect on the Epo-induced phosphorylation of ERK1 and ERK2. LY294002 also had no effect on Epo up-regulation of c-fos. MEK1 inhibitor PD98059 blocked both the c-myc and the c-fos responses to Epo. PD98059 and the PKC inhibitor H7 also blocked the phosphorylation of ERK1 and ERK2. PD98059 but not LY294002 inhibited Epo induction of ERK1 and ERK2 phosphorylation in normal erythroid cells. LY294002 blocked transcription of c-myc at exon 1. PD98059 had no effect on transcription from exon 1 but, rather, blocked Epo-induced c-myc elongation at the 3'-end of exon 1. These results identify two Epo signaling pathways to c-myc, one of which is PI3K-dependent operating on transcriptional initiation, whereas the other is mitogen-activated protein kinase-dependent operating on elongation.

  7. Generation and phenotypic analysis of a transgenic line of rabbits secreting active recombinant human erythropoietin in the milk

    Mikuš, Tomáš; Poplštein, M.; Sedláková, J.; Landa, Vladimír; Jeníková, Gabriela; Trefil, P.; Lidický, J.; Malý, Petr

    2004-01-01

    Roč. 13, č. 5 (2004), s. 487-498. ISSN 0962-8819 R&D Projects: GA ČR GA304/03/0090 Institutional research plan: CEZ:AV0Z5052915 Keywords : erythropoietin, mammary gland, transgenic rabbit Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.107, year: 2004

  8. Erythropoietin receptor is not a surrogate marker for tumor hypoxia and does not correlate with survival in head and neck squamous cell carcinomas

    Background and purpose: To evaluate erythropoietin receptor (EPOR) expression in human head and neck squamous cell carcinomas and correlate this to the presence of tumor hypoxia and treatment outcome. Patients and methods: Eighty-five patients with locally advanced tumors of the head and neck were included. Of these, 34 were given the hypoxia marker pimonidazole i.v. 2 h prior to biopsy taking. Contiguous paraffin embedded biopsies were stained for EPOR expression and, if administered, for pimonidazole binding. Immunohistochemical staining for EPOR was interpreted semiquantitatively according to a composite scale, ranging from 0 to 200. Pimonidazole positivity was quantitatively analyzed in a semiautomatic way. Results: Diffuse weak-to-moderate cytoplasmic and membrane EPOR immunostaining was observed in 80 of 85 biopsies (94%) and staining scores ranged from 0 to 198 (median 100). No correlations were found between EPOR expression, and the primary tumor site, T-stage or N-stage. Also, There was no association between EPOR expression and treatment outcome. The degree of tumor hypoxia represented by the relative area of pimonidazole binding varied between 0 and 26% (median 7%). Contiguous biopsy sections showed a lack of colocalization between EPOR and pimonidazole binding. Conclusion: EPOR expression was demonstrated in the majority of the head and neck tumors. No colocalization was found between EPOR expression and pimonidazole binding indicating that the presence or absence of hypoxia did not necessarily indicate a distinct pattern of EPOR expression. The level of EPOR expression was not of prognostic significance in patients with head and neck cancer, although small effects of EPOR cannot be excluded because of the sample size of this study

  9. Research Advances in Expression and Functions of Erythropoietin and Erythropoietin Receptor in Cancers%促红细胞生成素及其受体在恶性肿瘤组织中的表达及功能的研究进展

    李梅; 吕跃; 陈晓勤

    2008-01-01

    促红细胞生成素(erythropoietin,EPO)最早被发现在红系细胞增殖、分化中发挥主要调节作用.研究发现在多种不同非造血器官及组织中有EPO及促红细胞生成素受体(erythropoietin receptor,EPO-R)的表达,并发挥促血管形成及组织保护效应.最近的多项研究发现,EPO及EPO-R广泛表达于多种恶性肿瘤细胞,EPO/EPO-R的自分泌/旁分泌通路与肿瘤微血管形成、刺激肿瘤细胞增殖、抑制凋亡及对放化疗的敏感性有关.确切机制需进一步研究.重组人促红细胞生成素(recombinant human erythropoietin,rh-EPO)在临床上已广泛用于治疗肿瘤相关贫血.研究证实其能增加血红蛋白水平,减少红细胞输注,同时改善患者生活质量.但亦有随机试验报道了rh-EPO治疗的患者相对安慰剂组患者无进展生存期下降.我们对EPO及其受体在非造血组织尤其是肿瘤组织中的表达、功能及相关机制的研究进展作简要概述.

  10. Effect of recombinant human erythropoietin administration on lipid peroxidation and antioxidant enzyme(s activities in preterm infants.

    Akisu M

    2001-12-01

    Full Text Available In the present investigation, we studied the effect of recombinant human erythropoietin (r-HuEPO on serum malondialdehyde (MDA as an index of lipid peroxidation, related to iron-catalyzed free radical reaction and erythrocyte superoxide dismutase (SOD, catalase (CAT, and glutathione peroxidase (GPX activities in very-low-birth weight (VLBW infants. Forty premature infants, at gestational ages were less than 33 weeks and birthweights were less than 1,500 g, were enrolled in the study. The study population was randomly divided into 2 groups. Twenty infants in Group 1 (treatment group were given r-HuEPO, and 20 infants in Group 2 served as the control. r-HuEPO treatment (750 U/kg a week was initiated on the 10th day of life and continued for 6 weeks. Preterm infants given erythrocyte transfusions during the study were excluded from the results. Serum ferritin and MDA levels, and erythrocyte superoxide dismutase (SOD, catalase (CAT, and glutathione peroxidase (GPX activities were analyzed at the end of the first week of life (at the beginning of the study. Subsequently, serum ferritin, and MDA levels were measured at the end of the 3rd and the 6th week. SOD, CAT, and GPX activities in the hemolysate were analyzed at the end of the 4th week. Six infants in the control group and 1 infant in the r-HuEPO group received transfusions through the end of the study, and these infants were excluded from the results. Significantly decreased serum ferritin concentrations were found in the r-HuEPO group compared to those in the control group both at the end of the 3rd and the 6th week (P < 0.05, and P < 0.01, respectively. In addition, serum MDA levels were also significantly reduced in Group 1 compared to control both at the end of the 3rd and the 6th week (P < 0.01 and P < 0.05, respectively. A good correlation was found between serum MDA and ferritin levels in Group 1. When the 2 groups were compared with respect to activities of SOD, CAT, and GPX at the end

  11. Erythropoietin Pathway: A Potential Target for the Treatment of Depression

    Chongyang Ma; Fafeng Cheng; Xueqian Wang; Changming Zhai; Wenchao Yue; Yajun Lian; Qingguo Wang

    2016-01-01

    During the past decade, accumulating evidence from both clinical and experimental studies has indicated that erythropoietin may have antidepressant effects. In addition to the kidney and liver, many organs have been identified as secretory tissues for erythropoietin, including the brain. Its receptor is expressed in cerebral and spinal cord neurons, the hypothalamus, hippocampus, neocortex, dorsal root ganglia, nerve axons, and Schwann cells. These findings may highlight new functions for ery...

  12. High glucose stimulates the expression of erythropoietin in rat glomerular epithelial cells

    Lim, Seul Ki; Park, Soo Hyun

    2011-01-01

    It has been reported that the levels of erythropoietin are associated with diabetes mellitus. Glomerular epithelial cells, located in the renal cortex, play an important role in the regulation of kidney function and hyperglycemia-induced cell loss of glomerular epithelial cells is implicated in the onset of diabetic nephropathy. This study investigated the effect of high glucose on erythropoietin and erythropoietin receptor expression in rat glomerular epithelial cells. We found that 25 mM D-...

  13. Erythropoietin is involved in hemoprotein syntheses in developing human decidua.

    Shiota, Mitsuru; Yasuda, Yoshiko; Shimaoka, Masao; Tsuritani, Mitsuhiro; Koike, Eiji; Oiki, Masaaki; Matsubara, Junko; Taketani, Shigeru; Murakami, Hitoshi; Yamasaki, Harufumi; Okumoto, Katsumi; Hoshiai, Hiroshi

    2013-03-01

    Before establishment of feto-placental circulation, decidua can synthesize hemoproteins to maintain oxygen homeostasis in situ. Using the human decidua of induced abortions ranging from 5 to 8 weeks of gestation, we determined the expression levels of erythropoietin, erythropoietin receptor, cytoglobin, myoglobin, embryonic-, fetal- and adult hemoglobin mRNA by quantitative RT-PCR analysis and identified their proteins by Western blot and immunohistochemical analyses. Erythropoietin signaling was demonstrated in phosphatidylinositol-3-kinase/protein kinase B pathway by Western blot, and the transcriptional factors for erythroid and non-erythroid heme synthesis were examined by RT-PCR analysis. In decidua, erythropoietin and its receptor mRNAs, erythropoietin receptor protein and phosphatidylinositol-3-kinase, were expressed with a peak at 6 weeks of gestation. Moreover, the decidua during 5 to 8 weeks of gestation expressed embryonic, fetal and adult hemoglobins additionally cytoglobin and myoglobin at transcriptional and protein levels. The heme portion of these hemoproteins is considered to be synthesized by non-erythroid δ-aminolevulinate synthase. These hemoproteins were discernible especially in decidual cells concomitant with cytotrophoblast cells and macrophage in these developing decidua. Considering the different capacity for oxygen binding and dissociation among hemoglobins with the oxygen storage capacity for cytoglobin and myoglobin, these hemoproteins appear to play a role in oxygen demand in decidua in situ before development of feto-placental circulation under the control of erythropoietin signaling. PMID:23480354

  14. Cell encoding recombinant human erythropoietin

    Beck, A.K.; Withy, R.M.; Zabrecky, J.R.; Masiello, N.C.

    1990-09-04

    This patent describes a C127 cell transformed with a recombinant DNA vector. It comprises: a DNA sequence encoding human erythropoietin, the transformed cell being capable of producing N-linked and O-linked glycosylated human erythropoietin.

  15. Erythropoietin has a mitogenic and positive chemotactic effect on endothelial cells

    Anagnostou, A.; Kessimian, N.; Steiner, M. (Memorial Hospital of Rhode Island, Pawtucket (USA) Brown Univ. Program in Medicine, Providence, RH (USA)); Lee, Eun Sun (Memorial Hospital of Rhode Island, Pawtucket (USA)); Levinson, R. (Brown Univ. Program in Medicine, Providence, RI (USA))

    1990-08-01

    Erythropoietin is known to be a hematopoietic growth factor with a singularly specific action on the proliferation and differentiation of erythroid progenitor cells. The authors have observed a dose-dependent proliferative action of human recombinant erythropoietin on human umbilical vein endothelial cells and bovine adrenal capillary endothelial cells. Binding studies with radioiodinated recombinant human erythropoietin revealed a large number ({approx}27,000) of an apparent single class of receptors with an affinity in the 10{sup {minus}9} M range. Linkage of the radiolabeled ligand to its receptor via a bifunctional crosslinking agent allowed them to identify an endothelial cell protein of 45 kDa as the principal receptor associated with this mitogenic effect of erythropoietin. Recombinant human erythropoietin also enhanced the migration of endothelial cells.

  16. Erythropoietin has a mitogenic and positive chemotactic effect on endothelial cells

    Erythropoietin is known to be a hematopoietic growth factor with a singularly specific action on the proliferation and differentiation of erythroid progenitor cells. The authors have observed a dose-dependent proliferative action of human recombinant erythropoietin on human umbilical vein endothelial cells and bovine adrenal capillary endothelial cells. Binding studies with radioiodinated recombinant human erythropoietin revealed a large number (∼27,000) of an apparent single class of receptors with an affinity in the 10-9 M range. Linkage of the radiolabeled ligand to its receptor via a bifunctional crosslinking agent allowed them to identify an endothelial cell protein of 45 kDa as the principal receptor associated with this mitogenic effect of erythropoietin. Recombinant human erythropoietin also enhanced the migration of endothelial cells

  17. Erythropoietin and diabetes mellitus

    Kenneth; Maiese

    2015-01-01

    Erythropoietin(EPO) is a 30.4 k Da growth factor and cytokine that governs cell proliferation, immune modulation, metabolic homeostasis, vascular function, and cytoprotection. EPO is under investigation for the treatment of variety of diseases, but appears especially suited for the treatment of disorders of metabolism that include diabetes mellitus(DM). DM and the com-plications of this disease impact a significant portion of the global population leading to disability and death with currently limited therapeutic options. In addition to its utility for the treatment of anemia, EPO can improve cardiac function, reduce fatigue, and improve cognition in patients with DM as well as regulate cellular energy metabolism, obesity, tissue repair and regeneration, apoptosis, and autophagy in experimental models of DM. Yet, EPO can have adverse effects that involve the vasculature system and unchecked cellular proliferation. Critical to the cytoprotective capacity and the potential for a positive clinical outcome with EPO are the control of signal transduction pathways that include protein kinase B, the mechanistic target of rapamycin, Wnt signaling, mammalian forkhead transcription factors of the O class, silent mating type information regulation 2 homolog 1(Saccharomyces cerevisiae), and AMP activated protein kinase. Therapeutic strategies that can specifically target and control EPO and its signaling pathways hold great promise for the development of new and effective clinical treatments for DM and the complications of this disorder.

  18. Correlation between erythropoietic activity and body growth rate in hypertransfused polycythemic growing rats as the result of an erythropoietin-dependent operating mechanism

    The established relationship between erythropoietic activity and body growth rate in the polycythemic growing rat could be the result of either an erythropoietin (EPO)-dependent or an EPO-independent operating mechanism. The present study was thus undertaken to elucidate the nature of the aforementioned mechanism by assessing the ratio between plasma immunoreactive EPO (iEPO) concentration and erythropoietic activity in young hypertransfused rats for different body growth rates. Red blood cell (RBC)-59Fe uptake was about 75% in 21-day-old rats; it rapidly decreased with time when the animals were placed on a protein-free diet, approaching a level of about 1% by the 10th day of protein starvation. Over the same period plasma iEPO decreased from 55 mU/ml to 7 mU/ml. Body growth rate was 0. Following this ''protein depletion period'' the rats received diets containing different amounts of casein (''protein repletion period'') added isocalorically to the protein-free diet to elicit a rise in body growth rate. Statistically significant relationships (p less than 0.001) were found between dietary casein concentration and body growth rate (r = 0.991), dietary casein concentration and RBC-59Fe uptake (r = 0.991), dietary casein concentration and plasma iEPO level (r = 0.992), body growth rate and RBC-59Fe (r = 0.986), and body growth rate and plasma iEPO level (r = 0.994) in hypertransfused polycythemic rats during the protein repletion period. These findings suggest that the correlation between erythropoietic activity and growth rate in the growing rat is the result of an erythropoietin-dependent operating mechanism, which appears to be independent of the ratio tissue oxygen supply/tissue oxygen demand

  19. Mechanism for the activation of glutamate receptors

    Scientists at the NIH have used a technique called cryo-electron microscopy to determine a molecular mechanism for the activation and desensitization of ionotropic glutamate receptors, a prominent class of neurotransmitter receptors in the brain and spina

  20. A Simple Three-Step Method for Design and Affinity Testing of New Antisense Peptides: An Example of Erythropoietin

    Nikola Štambuk

    2014-05-01

    Full Text Available Antisense peptide technology is a valuable tool for deriving new biologically active molecules and performing peptide–receptor modulation. It is based on the fact that peptides specified by the complementary (antisense nucleotide sequences often bind to each other with a higher specificity and efficacy. We tested the validity of this concept on the example of human erythropoietin, a well-characterized and pharmacologically relevant hematopoietic growth factor. The purpose of the work was to present and test simple and efficient three-step procedure for the design of an antisense peptide targeting receptor-binding site of human erythropoietin. Firstly, we selected the carboxyl-terminal receptor binding region of the molecule (epitope as a template for the antisense peptide modeling; Secondly, we designed an antisense peptide using mRNA transcription of the epitope sequence in the 3'→5' direction and computational screening of potential paratope structures with BLAST; Thirdly, we evaluated sense–antisense (epitope–paratope peptide binding and affinity by means of fluorescence spectroscopy and microscale thermophoresis. Both methods showed similar Kd values of 850 and 816 µM, respectively. The advantages of the methods were: fast screening with a small quantity of the sample needed, and measurements done within the range of physicochemical parameters resembling physiological conditions. Antisense peptides targeting specific erythropoietin region(s could be used for the development of new immunochemical methods. Selected antisense peptides with optimal affinity are potential lead compounds for the development of novel diagnostic substances, biopharmaceuticals and vaccines.

  1. Carbamylated Erythropoietin: A Prospective Drug Candidate for Neuroprotection

    Jianmin Chen; Zheng Yang; Xiao Zhang

    2016-01-01

    Carbamylated erythropoietin (cEpo), which is neuroprotective but lacks hematopoietic activity, has been attracting rising concerns. However, the cellular and molecular mechanisms involved in the process of neuroprotection of cEpo are not well known. Based on several recent reports, the neuroprotective effects of cEpo are illustrated, and signaling pathways involved in the different effects of erythropoietin and cEpo are discussed. These newly reported researches may shed new light on the deve...

  2. EPOR-Based Purification and Analysis of Erythropoietin Mimetic Peptides from Human Urine by Cys-Specific Cleavage and LC/MS/MS

    Vogel, Matthias; Thomas, Andreas; Schänzer, Wilhelm; Thevis, Mario

    2015-09-01

    The development of a new class of erythropoietin mimetic agents (EMA) for treating anemic conditions has been initiated with the discovery of oligopeptides capable of dimerizing the erythropoietin (EPO) receptor and thus stimulating erythropoiesis. The most promising amino acid sequences have been mounted on various different polymeric structures or carrier molecules to obtain highly active EPO-like drugs exhibiting beneficial and desirable pharmacokinetic profiles. Concomitant with creating new therapeutic options, erythropoietin mimetic peptide (EMP)-based drug candidates represent means to artificially enhance endurance performance and necessitate coverage by sports drug testing methods. Therefore, the aim of the present study was to develop a strategy for the comprehensive detection of EMPs in doping controls, which can be used complementary to existing protocols. Three model EMPs were used to provide proof-of-concept data. Following EPO receptor-facilitated purification of target analytes from human urine, the common presence of the cysteine-flanked core structure of EMPs was exploited to generate diagnostic peptides with the aid of a nonenzymatic cleavage procedure. Sensitive detection was accomplished by targeted-SIM/data-dependent MS2 analysis. Method characterization was conducted for the EMP-based drug peginesatide concerning specificity, linearity, precision, recovery, stability, ion suppression/enhancement, and limit of detection (LOD, 0.25 ng/mL). Additionally, first data for the identification of the erythropoietin mimetic peptides EMP1 and BB68 were generated, demonstrating the multi-analyte testing capability of the presented approach.

  3. Erythropoietin Action in Stress Response, Tissue Maintenance and Metabolism

    Yuanyuan Zhang

    2014-06-01

    Full Text Available Erythropoietin (EPO regulation of red blood cell production and its induction at reduced oxygen tension provides for the important erythropoietic response to ischemic stress. The cloning and production of recombinant human EPO has led to its clinical use in patients with anemia for two and half decades and has facilitated studies of EPO action. Reports of animal and cell models of ischemic stress in vitro and injury suggest potential EPO benefit beyond red blood cell production including vascular endothelial response to increase nitric oxide production, which facilitates oxygen delivery to brain, heart and other non-hematopoietic tissues. This review discusses these and other reports of EPO action beyond red blood cell production, including EPO response affecting metabolism and obesity in animal models. Observations of EPO activity in cell and animal model systems, including mice with tissue specific deletion of EPO receptor (EpoR, suggest the potential for EPO response in metabolism and disease.

  4. EPO-independent functional EPO receptor in breast cancer enhances estrogen receptor activity and promotes cell proliferation

    Reinbothe, Susann; Larsson, Anna-Maria; Vaapil, Marica; Wigerup, Caroline [Department of Laboratory Medicine, Translational Cancer Research, Medicon Village, Lund University, SE-223 81 Lund (Sweden); CREATE Health, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv (Israel); Sun, Jianmin [Department of Laboratory Medicine, Translational Cancer Research, Medicon Village, Lund University, SE-223 81 Lund (Sweden); Jögi, Annika [Department of Laboratory Medicine, Translational Cancer Research, Medicon Village, Lund University, SE-223 81 Lund (Sweden); CREATE Health, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv (Israel); Neumann, Drorit [Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv (Israel); Rönnstrand, Lars [Department of Laboratory Medicine, Translational Cancer Research, Medicon Village, Lund University, SE-223 81 Lund (Sweden); Påhlman, Sven, E-mail: sven.pahlman@med.lu.se [Department of Laboratory Medicine, Translational Cancer Research, Medicon Village, Lund University, SE-223 81 Lund (Sweden); CREATE Health, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv (Israel)

    2014-02-28

    Highlights: • New anti-human EPOR antibody confirms full-length EPOR expression in breast cancer cells. • Proliferation of breast cancer cells is not affected by rhEPO treatment in vitro. • EPOR knockdown impairs proliferation of ERa positive breast cancer cells. • EPOR knockdown reduces AKT phosphorylation and ERa activity. - Abstract: The main function of Erythropoietin (EPO) and its receptor (EPOR) is the stimulation of erythropoiesis. Recombinant human EPO (rhEPO) is therefore used to treat anemia in cancer patients. However, clinical trials have indicated that rhEPO treatment might promote tumor progression and has a negative effect on patient survival. In addition, EPOR expression has been detected in several cancer forms. Using a newly produced anti-EPOR antibody that reliably detects the full-length isoform of the EPOR we show that breast cancer tissue and cells express the EPOR protein. rhEPO stimulation of cultured EPOR expressing breast cancer cells did not result in increased proliferation, overt activation of EPOR (receptor phosphorylation) or a consistent activation of canonical EPOR signaling pathway mediators such as JAK2, STAT3, STAT5, or AKT. However, EPOR knockdown experiments suggested functional EPO receptors in estrogen receptor positive (ERα{sup +}) breast cancer cells, as reduced EPOR expression resulted in decreased proliferation. This effect on proliferation was not seen in ERα negative cells. EPOR knockdown decreased ERα activity further supports a mechanism by which EPOR affects proliferation via ERα-mediated mechanisms. We show that EPOR protein is expressed in breast cancer cells, where it appears to promote proliferation by an EPO-independent mechanism in ERα expressing breast cancer cells.

  5. EPO-independent functional EPO receptor in breast cancer enhances estrogen receptor activity and promotes cell proliferation

    Highlights: • New anti-human EPOR antibody confirms full-length EPOR expression in breast cancer cells. • Proliferation of breast cancer cells is not affected by rhEPO treatment in vitro. • EPOR knockdown impairs proliferation of ERa positive breast cancer cells. • EPOR knockdown reduces AKT phosphorylation and ERa activity. - Abstract: The main function of Erythropoietin (EPO) and its receptor (EPOR) is the stimulation of erythropoiesis. Recombinant human EPO (rhEPO) is therefore used to treat anemia in cancer patients. However, clinical trials have indicated that rhEPO treatment might promote tumor progression and has a negative effect on patient survival. In addition, EPOR expression has been detected in several cancer forms. Using a newly produced anti-EPOR antibody that reliably detects the full-length isoform of the EPOR we show that breast cancer tissue and cells express the EPOR protein. rhEPO stimulation of cultured EPOR expressing breast cancer cells did not result in increased proliferation, overt activation of EPOR (receptor phosphorylation) or a consistent activation of canonical EPOR signaling pathway mediators such as JAK2, STAT3, STAT5, or AKT. However, EPOR knockdown experiments suggested functional EPO receptors in estrogen receptor positive (ERα+) breast cancer cells, as reduced EPOR expression resulted in decreased proliferation. This effect on proliferation was not seen in ERα negative cells. EPOR knockdown decreased ERα activity further supports a mechanism by which EPOR affects proliferation via ERα-mediated mechanisms. We show that EPOR protein is expressed in breast cancer cells, where it appears to promote proliferation by an EPO-independent mechanism in ERα expressing breast cancer cells

  6. Endocrine effects of erythropoietin.

    Carlson, H E; Graber, M L; Gelato, M C; Hershman, J M

    1995-06-01

    Uremic men may manifest a variety of hormonal abnormalities, including decreased serum concentrations of testosterone and thyroid hormones and increased serum levels of growth hormone and prolactin. Some previous investigations have reported that erythropoietin therapy may reverse these hormonal changes. To investigate this possibility further, we measured serum prolactin, testosterone, LH, FSH, TSH, free thyroxine, triiodothyronine, growth hormone and IGF-I in 21 generally elderly male hemodialysis patients before and during erythropoietin therapy; many of the patients also received an anabolic steroid or metoclopramide treatment. Despite a significant erythropoietic response in a majority of the subjects, no significant changes were seen in any of the hormonal parameters other than a small decrease in serum growth hormone concentrations. Advanced age and chronic illness in our patients may have played a role in limiting the hormonal response reported by others. PMID:8593965

  7. Erythropoietin and diabetes mellitus

    Maiese, Kenneth

    2015-01-01

    Erythropoietin (EPO) is a 30.4 kDa growth factor and cytokine that governs cell proliferation, immune modulation, metabolic homeostasis, vascular function, and cytoprotection. EPO is under investigation for the treatment of variety of diseases, but appears especially suited for the treatment of disorders of metabolism that include diabetes mellitus (DM). DM and the complications of this disease impact a significant portion of the global population leading to disability and death with currentl...

  8. Erythropoietin binding protein from mammalian serum

    Clemons, G.K.

    1997-04-29

    Purified mammalian erythropoietin binding-protein is disclosed, and its isolation, identification, characterization, purification, and immunoassay are described. The erythropoietin binding protein can be used for regulation of erythropoiesis by regulating levels and half-life of erythropoietin. A diagnostic kit for determination of level of erythropoietin binding protein is also described. 11 figs.

  9. Erythropoietin binding protein from mammalian serum

    Clemons, Gisela K. (Berkeley, CA)

    1997-01-01

    Purified mammalian erythropoietin binding-protein is disclosed, and its isolation, identification, characterization, purification, and immunoassay are described. The erythropoietin binding protein can be used for regulation of erythropoiesis by regulating levels and half-life of erythropoietin. A diagnostic kit for determination of level of erythropoietin binding protein is also described.

  10. Erythropoietin receptor expression of rat brain at different developmental maturity and the effects of lipopolysaccharide on erythropoietin receptor expression%不同成熟度大鼠脑组织促红细胞生成素受体的表达及脂多糖对其表达的影响

    郭佳佳; 张彦华; 段佳佳; 徐发林

    2014-01-01

    目的探讨不同成熟度大鼠脑组织促红细胞生成素(EPO)受体(EPO-R)的表达及脂多糖(LPS)对不同成熟度大鼠脑组织EPO-R表达的影响。方法2日龄(Postnatal day 2,P2)新生SD大鼠,随机分为A、B两组:A为正常对照组,B为LPS组,分别腹腔注射等容积0.9%氯化钠注射液或0.6 mg/(kg·d)的 LPS,连续应用5天(P2~P6),并续养至12日龄(P12)。A组于P2、P7、P12及B组于P7、P12各时间点随机抽取8只新生大鼠取脑,以矢状缝为标志分为左右半脑,右侧脑用酶联免疫吸附试验(ELISA)检测脑组织EPO-R蛋白水平,左侧脑用反转录聚合酶链式反应(RT-PCR)检测EPO-R mRNA水平。结果(1)随大鼠成熟度的增加,正常对照组大鼠脑EPO-R蛋白(P2:13.73±2.04、P7:11.01±3.36、P12:10.52±2.35)及EPO-R mRNA(P2:0.44±0.05、P7:0.39±0.03、P12:0.38±0.04)表达下调,P2时表达水平与P7比较,差异有显著性(P0.05);(2)LPS组EPO-R蛋白与EPO-R mRNA表达较正常对照组上调,7日龄时正常对照组与LPS组比较,差异有显著性(P0.05)。结论随大鼠成熟度增加,脑组织EPO-R表达下调;LPS可上调大鼠脑组织EPO-R表达。%ObjectiveTo investigate the Erythropoietin Receptor(EPO-R) expression of rat brain at different developmental maturity and the effects of infection on EPO-R expression.Method Postnatal day 2 (P2) newborn SD rats were randomly divided into 2 groups:Control group(equal volume of saline) and Lipopolysaccharide (LPS) group[0.6 mg/(kg·d) LPS].The newborn rats in each group were administered corresponding drugs respectively at the corresponding time by intraperitoneal injection for 5 consecutive days,and continued to raise until P12. Every 8 newborn rats in A groups on P2,P7 and P12 and B group on P7 and P12 were selected randomly , the brains was divided into left and right hemispheres marked by sagittal suture.ELISA method were adopted

  11. NMDA Receptor Activation by Spontaneous Glutamatergic Neurotransmission

    Espinosa, Felipe; Kavalali, Ege T.

    2009-01-01

    Under physiological conditions N-methyl-d-aspartate (NMDA) receptor activation requires coincidence of presynaptic glutamate release and postsynaptic depolarization due to the voltage-dependent block of these receptors by extracellular Mg2+. Therefore spontaneous neurotransmission in the absence of action potential firing is not expected to lead to significant NMDA receptor activation. Here we tested this assumption in layer IV neurons in neocortex at their resting membrane potential (approxi...

  12. Hormone activation of baculovirus expressed progesterone receptors.

    Elliston, J F; Beekman, J M; Tsai, S Y; O'Malley, B W; Tsai, M J

    1992-03-15

    Human and chicken progesterone receptors (A form) were overproduced in a baculovirus expression system. These recombinant progesterone receptors were full-length bound progesterone specifically and were recognized by monoclonal antibodies, AB52 and PR22, specific for human and chicken progesterone receptor, respectively. In gel retardation studies, binding of recombinant human and chicken progesterone receptors to their progesterone response element (PRE) was specific and was enhanced in the presence of progesterone. Binding of human progesterone receptor to the PRE was also enhanced in the presence of the antiprogestin, RU486, but very little effect was observed in the presence of estradiol, dexamethasone, testosterone, and vitamin D. In our cell-free transcription system, human progesterone receptor induced transcription in a receptor-dependent and hormone-activable manner. Receptor-stimulated transcription required the presence of the PRE in the test template and could be specifically inhibited by excess PRE oligonucleotides. Furthermore, chicken progesterone receptor also induced in vitro transcription in a hormone-activable manner. These results demonstrate that steroid receptors overexpressed in a baculovirus expression system are functional and exhibit steroid-responsive binding and transcription. These observations support our present understanding of the mechanism of steroid receptor-regulated gene expression and provide a technological format for studies of the role of hormone and antihormone in altering gene expression. PMID:1544902

  13. NMDA receptor activation by spontaneous glutamatergic neurotransmission.

    Espinosa, Felipe; Kavalali, Ege T

    2009-05-01

    Under physiological conditions N-methyl-D-aspartate (NMDA) receptor activation requires coincidence of presynaptic glutamate release and postsynaptic depolarization due to the voltage-dependent block of these receptors by extracellular Mg(2+). Therefore spontaneous neurotransmission in the absence of action potential firing is not expected to lead to significant NMDA receptor activation. Here we tested this assumption in layer IV neurons in neocortex at their resting membrane potential (approximately -67 mV). In long-duration stable recordings, we averaged a large number of miniature excitatory postsynaptic currents (mEPSCs, >100) before or after application of dl-2 amino 5-phosphonovaleric acid, a specific blocker of NMDA receptors. The difference between the two mEPSC waveforms showed that the NMDA current component comprises approximately 20% of the charge transfer during an average mEPSC detected at rest. Importantly, the contribution of the NMDA component was markedly enhanced at membrane potentials expected for the depolarized up states (approximately -50 mV) that cortical neurons show during slow oscillations in vivo. In addition, partial block of the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor component of the mEPSCs did not cause a significant reduction in the NMDA component, indicating that potential AMPA receptor-driven local depolarizations did not drive NMDA receptor activity at rest. Collectively these results indicate that NMDA receptors significantly contribute to signaling at rest in the absence of dendritic depolarizations or concomitant AMPA receptor activity. PMID:19261712

  14. The discovery of erythropoietin.

    Erslev, A J

    1993-01-01

    A personal vignette of life as a resident and fellow at the Yale New Haven Hospital in the early 1950s follows. John Peters and his associates created a superb renal center at Yale New Haven, and they instilled in me a respect for quantitative measurements and a love for simple physiologic concepts. The environment was ideal for clinical and laboratory research, and it enabled me to show the existence of a regulatory erythropoietic hormone. I consider it a tribute to Dr. Peters that erythropoietin was later found to be produced by the kidneys and that it, as a recombinant drug, has helped ameliorate the anemia of uremia. PMID:8324267

  15. The effect of erythropoietin on platelet function and fibrinolysis in chronic renal failure

    Stenver, Doris Irene; Jeppesen, L; Nielsen, B;

    1994-01-01

    The influence of erythropoietin therapy on platelet function and fibrinolysis was evaluated in 12 anemic hemodialysis patients. Six months of therapy with human erythropoietin (50 to 80 IU/kg initially) raised the hemoglobin level to 10.8 g/dl but did not increase platelet activity in vivo as mea...

  16. Designing a small molecule erythropoietin mimetic.

    Guarnieri, Frank

    2015-01-01

    Erythropoietin (EPO) is a protein made by the kidneys in response to low red blood cell count that is secreted into the bloodstream and binds to a receptor on hematopoietic stem cells in the bone marrow inducing them to become new red blood cells. EPO made with recombinant DNA technology was brought to market in the 1980s to treat anemia caused by kidney disease and cancer chemotherapy. Because EPO infusion was able to replace blood transfusions in many cases, it rapidly became a multibillion dollar per year drug and as the first biologic created with recombinant technology it launched the biotech industry. For many years intense research was focused on creating a small molecule orally available EPO mimetic. The Robert Wood Johnson (RWJ) group seemed to definitively establish that only large peptides with a minimum of 60 residues could replace EPO, as anything less was not a full agonist. An intense study of the published work led me to hypothesize that the size of the mimetic is not the real issue, but the symmetry making and breaking of the EPO receptor induced by the ligand is the key to activating the stem cells. This analysis meant that residues in the binding site of the receptor deemed absolutely essential for ligand binding and activation from mutagenesis experiments, were probably not really that important. My fundamental hypotheses were: (a) the symmetric state of the homodimeric receptor is the most stable state and thus must be the off-state, (b) a highly localized binding site exists at a pivot point where the two halves of the receptor meet, (c) small molecules can be created that have high potency for this site that will be competitive with EPO and thus can displace the protein-protein interaction, (d) small symmetric molecules will stabilize the symmetric off-state of the receptor, and (e) a key asymmetry in the small molecule will stabilize a mirror image asymmetry in the receptor resulting in the stabilization of the on-state and proliferation of

  17. Androgen insensitivity syndrome: gonadal androgen receptor activity

    To determine whether abnormalities of the androgen receptor previously observed in skin fibroblasts from patients with androgen insensitivity syndrome also occur in the gonads of affected individuals, androgen receptor activity in the gonads of a patient with testicular feminization syndrome was investigated. Using conditions for optimal recovery of androgen receptor from human testes established by previous studies, we detected the presence of a high-affinity (dissociation constant . 3.2 X 10(-10) mol/L), low-capacity (4.2 X 10(-12) mol/mg DNA), androgen-binding protein when tritium-labeled R1881 was incubated at 4 degrees C with nuclear extracts from the gonads of control patients or from a patient with testicular feminization syndrome but not when incubated at 37 degrees C. Thus this patient has an androgen receptor with a temperature lability similar to that of receptors from normal persons

  18. Erythropoietin Signaling Promotes Invasiveness of Human Head and Neck Squamous Cell Carcinoma

    Ahmed Mohyeldin

    2005-05-01

    Full Text Available Erythropoietin (Epo is used for managing anemia in cancer patients. However, recent studies have raised concerns for this practice. We investigated the expression and function of Epo and the erythropoietin receptor (EpoR in tumor biopsies and cell lines from human head and neck cancer. Epo responsiveness of the cell lines was assessed by Epoetin-α-induced tyrosine phosphorylation of the Janus kinase 2 (JAK2 protein kinase. Transmigration assays across Matrigel-coated filters were used to examine the effects of Epoetin-A on cell invasiveness. In 32 biopsies, we observed a significant association between disease progression and expression of Epo and its receptor, EpoR. Expression was highest in malignant cells, particularly within hypoxic and infiltrating tumor regions. Although both Epo and EpoR were expressed in human head and neck carcinoma cell lines, only EpoR was upregulated by hypoxia. Epoetin-α treatment induced prominent JAK2 phosphorylation and enhanced cell invasion. Inhibition of JAK2 phosphorylation reduced both basal and Epo-induced invasiveness. Our findings support a role for autocrine or paracrine Epo signaling in the malignant progression and local invasiveness of head and neck cancer. This mechanism may also be activated by recombinant Epo therapy and could potentially produce detrimental effects in rhEpo-treated cancer patients.

  19. 21 CFR 864.7250 - Erythropoietin assay.

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Erythropoietin assay. 864.7250 Section 864.7250... assay. (a) Identification. A erythropoietin assay is a device that measures the concentration of erythropoietin (an enzyme that regulates the production of red blood cells) in serum or urine. This...

  20. Biased Signaling of Protease-activated Receptors

    PeishenZhao; NigelWilliamBunnett

    2014-01-01

    In addition to their role in protein degradation and digestion, proteases can also function as hormone-like signaling molecules that regulate vital patho-physiological processes, including inflammation, hemostasis, pain and repair mechanisms. Certain proteases can signal to cells by cleaving protease-activated receptors (PARs), a family of four G protein-coupled receptors. PARs are expressed by almost all cell types, control important physiological and disease-relevant processes, and are an e...

  1. [Erythropoietin and drug resistance in breast and ovarian cancers].

    Szenajch, Jolanta M; Synowiec, Agnieszka E

    2016-01-01

    Recombinant human erythropoietin (rhEPO) is used in breast and ovarian cancer patients to alleviate cancer- and chemotherapy-related anemia. Some clinical trials have reported that rhEPO may adversely impact survival and increase the risk of thrombovascular events in patients with breast cancer but not with ovarian cancer. The latter may potentially benefit the most from rhEPO treatment due to the nephrotoxic and myelosuppresive effects of standard platinum-based chemotherapy used in ovarian cancer disease. However, over the last decade the preclinical data have revealed that EPO is not only the principal growth factor and the hormone which regulates erythropoiesis, but also a cytokine with a pleiotropic activity which also can affect cancer cells. EPO can stimulate survival, ability to form metastases and drug resistance not only in continuous breast- and ovarian cancer cell lines but also in breast cancer stem-like cells. EPO receptor (EPOR) can also be constitutively active in both these cancers and, in breast cancer cells, may act in an interaction with estrogen receptor (ER) and epidermal growth factor receptor-2 (HER-2). EPOR, by an EPO-independent mechanism, promotes proliferation of breast cancer cells in cooperation with estrogen receptor, resulting in decreased effectiveness of tamoxifen treatment. In another interaction, as a result of the molecular antagonism between EPOR and HER2, rhEPO protects breast cancer cells against trastuzumab. Both clinical and preclinical evidence strongly suggest the urgent need to reevaluate the traditional use of rhEPO in the oncology setting. PMID:27321103

  2. Erythropoietin reduces storage lesions and decreases apoptosis indices in blood bank red blood cells

    Oscar Andrés Penuela

    2016-02-01

    Full Text Available ABSTRACT Background: Recent evidence shows a selective destruction of the youngest circulating red blood cells (neocytolysis trigged by a drop in erythropoietin levels. Objective: The aim of this study was to evaluate the effect of recombinant human erythropoietin beta on the red blood cell storage lesion and apoptosis indices under blood bank conditions. Methods: Each one of ten red blood cell units preserved in additive solution 5 was divided in two volumes of 100 mL and assigned to one of two groups: erythropoietin (addition of 665 IU of recombinant human erythropoietin and control (isotonic buffer solution was added. The pharmacokinetic parameters of erythropoietin were estimated and the following parameters were measured weekly, for six weeks: Immunoreactive erythropoietin, hemolysis, percentage of non-discocytes, adenosine triphosphate, glucose, lactate, lactate dehydrogenase, and annexin-V/esterase activity. The t-test or Wilcoxon's test was used for statistical analysis with significance being set for a p-value 6 weeks under blood bank conditions, with persistent supernatant concentrations of erythropoietin during the entire storage period. Adenosine triphosphate was higher in the Erythropoietin Group in Week 6 (4.19 ± 0.05 µmol/L vs. 3.53 ± 0.02 µmol/L; p-value = 0.009. The number of viable cells in the Erythropoietin Group was higher than in the Control Group (77% ± 3.8% vs. 71% ± 2.3%; p-value <0.05, while the number of apoptotic cells was lower (9.4% ± 0.3% vs. 22% ± 0.8%; p-value <0.05. Conclusions: Under standard blood bank conditions, an important proportion of red blood cells satisfy the criteria of apoptosis. Recombinant human erythropoietin beta seems to improve storage lesion parameters and mitigate apoptosis.

  3. ERK activation causes epilepsy by stimulating NMDA receptor activity

    Nateri, Abdolrahman S.; Raivich, Gennadij; Gebhardt, Christine; Da Costa, Clive; Naumann, Heike; Vreugdenhil, Martin; Makwana, Milan; Brandner, Sebastian; Adams, Ralf H.; Jefferys, John G. R.; Kann, Oliver; Behrens, Axel

    2007-01-01

    The ERK MAPK signalling pathway is a highly conserved kinase cascade linking transmembrane receptors to downstream effector mechanisms. To investigate the function of ERK in neurons, a constitutively active form of MEK1 (caMEK1) was conditionally expressed in the murine brain, which resulted in ERK activation and caused spontaneous epileptic seizures. ERK activation stimulated phosphorylation of eukaryotic translation initiation factor 4E (eIF4E) and augmented NMDA receptor 2B (NR2B) protein ...

  4. Mechanism of FGF receptor dimerization and activation

    Sarabipour, Sarvenaz; Hristova, Kalina

    2016-01-01

    Fibroblast growth factors (fgfs) are widely believed to activate their receptors by mediating receptor dimerization. Here we show, however, that the FGF receptors form dimers in the absence of ligand, and that these unliganded dimers are phosphorylated. We further show that ligand binding triggers structural changes in the FGFR dimers, which increase FGFR phosphorylation. The observed effects due to the ligands fgf1 and fgf2 are very different. The fgf2-bound dimer structure ensures the smallest separation between the transmembrane (TM) domains and the highest possible phosphorylation, a conclusion that is supported by a strong correlation between TM helix separation in the dimer and kinase phosphorylation. The pathogenic A391E mutation in FGFR3 TM domain emulates the action of fgf2, trapping the FGFR3 dimer in its most active state. This study establishes the existence of multiple active ligand-bound states, and uncovers a novel molecular mechanism through which FGFR-linked pathologies can arise.

  5. NMDA receptor activity in neuropsychiatric disorders

    ShaheenELakhan

    2013-06-01

    Full Text Available N-Methyl-D-aspartate (NMDA receptors play a variety of physiologic roles and their proper signaling is essential for cellular homeostasis. Any disruption in this pathway, leading to either enhanced or decreased activity, may result in the manifestation of neuropsychiatric pathologies such as schizophrenia, mood disorders, substance induced psychosis, Huntington's disease, Alzheimer's disease, and neuropsychiatric systemic lupus erythematosus. Here, we explore the notion that the overlap in activity of at least one biochemical pathway, the NMDA receptor pathway, may be the link to understanding the overlap in psychotic symptoms between diseases. This review intends to present a broad overview of those neuropsychiatric disorders for which alternations in NMDA receptor activity is prominent thus suggesting that continued direction of pharmaceutical intervention to this pathway may present a viable option for managing symptoms.

  6. No evidence for protective erythropoietin alpha signalling in rat hepatocytes

    Frede Stilla

    2009-04-01

    Full Text Available Abstract Background Recombinant human erythropoietin alpha (rHu-EPO has been reported to protect the liver of rats and mice from ischemia-reperfusion injury. However, direct protective effects of rHu-EPO on hepatocytes and the responsible signalling pathways have not yet been described. The aim of the present work was to study the protective effect of rHu-EPO on warm hypoxia-reoxygenation and cold-induced injury to hepatocytes and the rHu-EPO-dependent signalling involved. Methods Loss of viability of isolated rat hepatocytes subjected to hypoxia/reoxygenation or incubated at 4°C followed by rewarming was determined from released lactate dehydrogenase activity in the absence and presence of rHu-EPO (0.2–100 U/ml. Apoptotic nuclear morphology was assessed by fluorescence microscopy using the nuclear fluorophores H33342 and propidium iodide. Erythropoietin receptor (EPOR, EPO and Bcl-2 mRNAs were quantified by real time PCR. Activation of JAK-2, STAT-3 and STAT-5 in hepatocytes and rat livers perfused in situ was assessed by Western blotting. Results In contrast to previous in vivo studies on ischemia-reperfusion injury to the liver, rHu-EPO was without any protective effect on hypoxic injury, hypoxia-reoxygenation injury and cold-induced apoptosis to isolated cultured rat hepatocytes. EPOR mRNA was identified in these cells but specific detection of the EPO receptor protein was not possible due to the lack of antibody specificity. Both, in the cultured rat hepatocytes (10 U/ml for 15 minutes and in the rat liver perfused in situ with rHu-EPO (8.9 U/ml for 15 minutes no evidence for EPO-dependent signalling was found as indicated by missing effects of rHu-EPO on phosphorylation of JAK-2, STAT-3 and STAT-5 and on the induction of Bcl-2 mRNA. Conclusion Together, these results indicate the absence of any protective EPO signalling in rat hepatocytes. This implies that the protection provided by rHu-EPO in vivo against ischemia-reperfusion and

  7. Haemostatic aspects of recombinant human erythropoietin in colorectal surgery

    Poulsen, K A; Qvist, N; Winther, K;

    1998-01-01

    OBJECTIVE: To find out whether recombinant human erythropoietin (r-HuEPO) given perioperatively has any effect on haemostatic activity in patients undergoing elective colorectal resection. DESIGN: A placebo-controlled double-blind study. SETTING: Odense university hospital, Denmark. SUBJECTS: 24...

  8. Anxiolytic activity of adenosine receptor activation in mice.

    Jain, N; Kemp, N; Adeyemo, O; Buchanan, P; Stone, T W

    1995-10-01

    1. Purine analogues have been examined for anxiolytic- and anxiogenic-like activity in mice, by use of the elevated plus-maze. 2. The selective A1 receptor agonist, N6-cyclopentyladenosine (CPA) had marked anxiolytic-like activity at 10 and 50 microg kg(-1), with no effect on locomotor performance at these doses. 3. The A1 selective adenosine receptor antagonist, 1,3-dipropyl-8-cyclopentylxanthine (CPX) had no significant effect on anxiety-related measures or locomotor behaviour, but blocked the anxiolytic-like activity of CPA. The hydrophilic xanthine, 8-(p-sulphophenyl) theophylline did not prevent anxiolysis by CPA. 4. Caffeine had anxiogenic-like activity at 30 mg kg(-1) which was prevented by CPA at 50 micro kg(-1). 5. The A2 receptor agonist, N6-[2-(3,5-dimethoxyphenyl)-2(2-methylphenyl)-ethyl]adenosine (DPMA) had no effect on anxiety behaviour but depressed locomotor activity at the highest dose tested of 1 mg kg(-1). The A2 receptor antagonist, 1,3-dimethyl-l-propargylxanthine (DMPX) had no effect on anxiety-related measures or locomotion and did not modify the anxiolytic-like activity of CPA. 6. Administration of DPMA in combination with anxiolytic doses of CPA prevented the anxiolytic-like activity of the latter. 7. The results suggest that the selective activation of central A1 adenosine receptors induces anxiolytic-like behaviour, while the activation of A2 sites causes locomotor depression and reduces the effects of A1 receptor activation. The absence of any effect of CPX alone suggests that the receptors involved in modulating behaviour in the elevated plus-maze in mice are not activated tonically by endogenous adenosine. PMID:8640355

  9. Recombinant erythropoietin for the anaemia of patients with advanced Gastrointestinal Stromal Tumours (GIST receiving imatinib: an active agent only in non progressive patients

    Duffaud Florence

    2012-09-01

    Full Text Available Abstract Recombinant erythropoietin for the anaemia of patients with advanced Gastrointestinal Stromal Tumours (GIST receiving imatinib : an active agent only in non progressive patients. Background Imatinib is a standard treatment for advanced/metastatic GIST and in adjuvant setting. Anaemia is frequently observed in patients with advanced GIST, and is one of the most frequent side effects of imatinib with grade 3–4 anaemia in 10% of patients. Whether EPO treatment is useful in the management of GIST patients receiving imatinib treatment is unknown. Methods A retrospective study of EPO treatment in GIST patients receiving imatinib was undertaken in 4 centres. Thirty four patients received EPO treatment among the 319 GIST patients treated with imatinib in clinical trials or with compassionate use between 2001 and 2003. The efficacy of EPO on the anaemia of patients with GIST treated with imatinib was analyzed. Results There were 18 males and 16 females with a median age of 59 years. Median WHO-PS was 1. Primary tumour sites were mainly gastric (32% and small bowel (29%. Sites of metastases were mainly liver (82% and peritoneum (79%. The median delay between the initiation of imatinib treatment and EPO was 58 days (range 0–553. Median haemoglobin (Hb level prior to EPO was 9 g/dL (range 6,9-11,8 and 11,7 g/dL (range 6,8-14,4 after 2 months. An increase of more than 2 g/dL was observed in 18 (53% of patients. None of the 7 patients who progressed (PD under imatinib treatment (400 mg/day experienced HB response, as compared to 66% (18/27 of the remaining patients (PR + SD (p = 0,002. Primary tumour site, liver metastases, peritoneal metastases, age, gender did not correlate with HB response to EPO. Response to EPO was observed in 2/11 patients receiving high-dose imatinib (800 mg/day vs 16/23 of others. Using logistic regression, only PD before EPO treatment was retained as a predictive factor for EPO response. Conclusion EPO enables to

  10. CERAPP: Collaborative estrogen receptor activity prediction project

    Mansouri, Kamel; Abdelaziz, Ahmed; Rybacka, Aleksandra;

    2016-01-01

    Background: Humans are exposed to thousands of man-made chemicals in the environment. Some chemicals mimic natural endocrine hormones and, thus, have the potential to be endocrine disruptors. Most of these chemicals have never been tested for their ability to interact with the estrogen receptor (ER......). Risk assessors need tools to prioritize chemicals for evaluation in costly in vivo tests, for instance, within the U.S. EPA Endocrine Disruptor Screening Program. oBjectives: We describe a large-scale modeling project called CERAPP (Collaborative Estrogen Receptor Activity Prediction Project) and...

  11. Spongian diterpenoids inhibit androgen receptor activity

    Yang, Yu Chi; Labros G Meimetis; Tien, Amy H; Mawji, Nasrin R.; Carr, Gavin; Wang, Jun; Andersen, Raymond J.; Sadar, Marianne D.

    2013-01-01

    Androgen receptor (AR) is a ligand-activated transcription factor and a validated drug target for all stages of prostate cancer. Antiandrogens compete with physiological ligands for AR ligand-binding domain (LBD). High-throughput screening of a marine natural product library for small molecules that inhibit AR transcriptional activity yielded the furanoditerpenoid spongia-13(16),-14-dien-19-oic acid, designated terpene 1 (T1). Characterization of T1 and the structurally related semi-synthetic...

  12. Hepatic erythropoietin response in cirrhosis

    Risør, Louise M; Fenger, Mogens; Olsen, Niels V;

    2016-01-01

    Background Erythropoietin (EPO) is produced in the liver during fetal life, but after birth the production shifts to the kidneys. The liver maintains a production capacity of 10% of the total EPO-production, but can be up-regulated to 100%. Previous studies have demonstrated both elevated and...

  13. Fatty acids activate a chimera of the clofibric acid-activated receptor and the glucocorticoid receptor.

    Göttlicher, M; Widmark, E; Q. Li; Gustafsson, J.A.

    1992-01-01

    Peroxisome proliferators such as clofibric acid, nafenopin, and WY-14,643 have been shown to activate PPAR (peroxisome proliferator-activated receptor), a member of the steroid nuclear receptor superfamily. We have cloned the cDNA from the rat that is homologous to that from the mouse [Issemann, I. & Green, S. (1990) Nature (London) 347, 645-650], which encodes a 97% similar protein with a particularly well-conserved putative ligand-binding domain. To search for physiologically occurring acti...

  14. Human Receptor Activation by Aroclor 1260, a Polychlorinated Biphenyl Mixture

    Wahlang, Banrida; Falkner, K. Cameron; Clair, Heather B.; Al-Eryani, Laila; Prough, Russell A.; States, J. Christopher; Coslo, Denise M.; Omiecinski, Curtis J.; Cave, Matthew C.

    2014-01-01

    Polychlorinated biphenyls (PCBs) are persistent environmental toxicants, present in 100% of U.S. adults and dose-dependently associated with obesity and non-alcoholic fatty liver disease (NAFLD). PCBs are predicted to interact with receptors previously implicated in xenobiotic/energy metabolism and NAFLD. These receptors include the aryl hydrocarbon receptor (AhR), pregnane xenobiotic receptor (PXR), constitutive androstane receptor (CAR), peroxisome proliferator-activated receptors (PPARs), ...

  15. Erythropoietin ameliorates podocyte injury in advanced diabetic nephropathy in the db/db mouse.

    Loeffler, Ivonne; Rüster, Christiane; Franke, Sybille; Liebisch, Marita; Wolf, Gunter

    2013-09-15

    Podocyte damage and accumulation of advanced glycation end products (AGEs) are characteristics of diabetic nephropathy (DN). The pathophysiology of AGE-challenged podocytes, such as hypertrophy, apoptosis, and reduced cell migration, is closely related to the induction of the cell cycle inhibitor p27(Kip1) and to the inhibition of neuropilin 1 (NRP1). We have previously demonstrated that treatment with erythropoietin is associated with protective effects for podocytes in vitro. db/db mice with overt DN aged 15-16 wk were treated with either placebo, epoetin-β, or continuous erythropoietin receptor activator (CERA) for 2 wk. db/db mice compared with nondiabetic db/m control mice revealed the expected increases in body weight, blood glucose, albumin-to-creatinine ratio, and AGE accumulation. Whereas there were no differences in body weight, hyperglycemia and AGEs were observed among diabetic mice that received epoetin-β compared with CERA and placebo treatment, indicating that epoetin-β/CERA treatment does not interfere with the development of diabetes in this model. However, the albumin-to-creatinine ratio was significantly lower in db/db mice treated with epoetin-β or CERA. Furthermore, kidney weights in db/db mice were increased compared with db/m control mice, indicating renal hypertrophy, whereas the increase in renal weight in epoetin-β- or CERA-treated db/db mice was significantly lower than in placebo-treated control mice. Induction of p27(Kip1) and suppression of NRP1 were significantly reduced in the epoetin-β treatment group versus the CERA treatment group. Furthermore, erythropoietin treatment diminished the diabetes-induced podocyte loss. Together, independently from hematopoetic effects, epoetin-β or CERA treatment was associated with protective changes in DN, especially that NRP1 and p27(Kip1) expressions as well as numbers of podocytes returned to normal levels. Our data show, for the first time, that medication of overt DN with erythropoietin

  16. RELAXIN ACTIVATES PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR GAMMA

    Singh, Sudhir; Bennett, Robert G

    2009-01-01

    Relaxin is a polypeptide hormone that triggers multiple signaling pathways through its receptor RXFP1. Many of relaxin’s functions, including vascular and antifibrotic effects, are similar to those induced by activation of PPARγ. In this study, we tested the hypothesis that relaxin signaling through RXFP1 would activate PPARγ activity. In cells overexpressing RXFP1 (HEK-RXFP1), relaxin increased transcriptional activity through a PPAR response element (PPRE) in a concentration-dependent manne...

  17. Functional significance of erythropoietin in renal cell carcinoma

    One of the molecules regulated by the transcription factor, hypoxia inducible factor (HIF), is the hypoxia-responsive hematopoietic factor, erythropoietin (EPO). This may have relevance to the development of renal cell carcinoma (RCC), where mutations of the von Hippel-Lindau (VHL) gene are major risk factors for the development of familial and sporadic RCC. VHL mutations up-regulate and stabilize HIF, which in turn activates many downstream molecules, including EPO, that are known to promote angiogenesis, drug resistance, proliferation and progression of solid tumours. HIFs typically respond to hypoxic cellular environment. While the hypoxic microenvironment plays a critical role in the development and progression of tumours in general, it is of special significance in the case of RCC because of the link between VHL, HIF and EPO. EPO and its receptor, EPOR, are expressed in many cancers, including RCC. This limits the use of recombinant human EPO (rhEPO) to treat anaemia in cancer patients, because the rhEPO may be stimulatory to the cancer. EPO may also stimulate epithelial-mesenchymal transition (EMT) in RCC, and pathological EMT has a key role in cancer progression. In this mini review, we summarize the current knowledge of the role of EPO in RCC. The available data, either for or against the use of EPO in RCC patients, are equivocal and insufficient to draw a definitive conclusion

  18. Renal mesangial cell cultures as a model for study of erythropoietin production.

    Kurtz, Armin; Jelkmann, W; Sinowatz, F.; Bauer, Christian

    1983-01-01

    Mesangial cells derived from isolated glomeruli of rat kidney were grown as homogeneous cell lines in culture. They released, into the culture medium, erythropoietin that had free terminal galactosyl residues and was therefore not active in vivo. The production of erythropoietin by these cells was significantly enhanced by either lowering the PO2 in the incubation atmosphere or by adding cobalt chloride to the culture medium. Therefore, mesangial cells in culture may be considered as an in vi...

  19. Anxiolytic activity of adenosine receptor activation in mice.

    Jain, N; Kemp, N; Adeyemo, O; Buchanan, P.; Stone, T W

    1995-01-01

    1. Purine analogues have been examined for anxiolytic- and anxiogenic-like activity in mice, by use of the elevated plus-maze. 2. The selective A1 receptor agonist, N6-cyclopentyladenosine (CPA) had marked anxiolytic-like activity at 10 and 50 microg kg(-1), with no effect on locomotor performance at these doses. 3. The A1 selective adenosine receptor antagonist, 1,3-dipropyl-8-cyclopentylxanthine (CPX) had no significant effect on anxiety-related measures or locomotor behaviour, but blocked ...

  20. Synthesis and biological evaluation of 125I-erythropoietin as a potential radiopharmaceutical agent for tumours

    Erythropoietin (EPO) is a glycoprotein hormone responsible for regulating erythropoiesis. Expression of EPO and EPO receptors (EPOr) has recently been demonstrated in some neoplastic cell lines and tumours, suggesting a potential new target for therapy. In this work, EPO was labeled with iodine-125 using the lactoperoxidase method, known to prevent damage to protein during radioiodination, and labeling conditions were optimized. In vitro stability studies have shown that 125I-EPO is radiochemically stable for 20 days after radiolabeling. In vitro cell binding studies have demonstrated very low binding (125I-EPO. In mice with induced melanoma, only a residual fixation in the tumour was evident. Further studies are warranted on other tumoral cell lines to better understand the binding process and internalization into cells. Studies on EPO labeled with carbon-11 could be valuable, since there is a greater chance of preserving the biological activity of the protein using this method. (author)

  1. Clinical study on relationship between recombinant human erythropoietin in treating patients with cancer-related anemia and its relation to serum erythropoietin and transferrin receptor%重组人促红细胞生成素治疗肿瘤相关性贫血及其与血清促红细胞生成素、转铁蛋白受体关系的临床研究

    丁瑞敏

    2015-01-01

    目的:分析肿瘤相关性贫血经重组人促红细胞生成素治疗的效果及血清促红细胞生成素、转铁蛋白受体检测的指导价值。方法:选取2012年6月-2013年12月期间,本院收治的肿瘤相关性贫血患者为研究对象(72例),并选取同期收治的单纯性缺铁性贫血患者40例为常模组。经放射免疫分析法和ELISA抗体法分别测定血清促红细胞生成素和血清转铁蛋白受体水平。结果:玉组、域组患者治疗后的红细胞积压和血红蛋白水平均有改善,P0. 05. After 8 weeks of treat-ment targets difference compared to before treatment, P<0. 05. Conclusion:serum erythropoietin and Transferrin receptor levels is important for the determination of treatment on tumor-related anemia guide value.

  2. Relaxin Family Peptide Receptor 1 (RXFP1) Activation Stimulates the Peroxisome Proliferator-Activated Receptor Gamma

    Singh, Sudhir; Bennett, Robert G

    2009-01-01

    Relaxin (Rlx) has antifibrotic effects in a number of tissues. Many of these effects are similar to those induced by the activators of peroxisome proliferator-activated receptor γ (PPARγ), raising the possibility that a mechanism for Rlx’s antifibrotic effects may involve activation of the PPARγ pathway. This study investigates the effect of Rlx on PPARs and their mechanism of upregulation. It shows that Rlx stimulates ligand-independent PPAR activation in a dose-dependent manner. The combine...

  3. Erythropoietin in the Neurology ICU

    Robertson, Claudia; Sadrameli, Saeed

    2013-01-01

    Erythropoietin (EPO) is an approved drug that is used in the treatment of chronic anemia associated with chronic renal failure. In the Neuro ICU, there are two potential uses for treatment with EPO. Anemia is common in patients with acute neurological disorders and may be a cause of secondary insults. Studies of EPO to treat anemia associated with critical illness have not conclusively shown a beneficial risk/benefit ratio. The relatively small reduction in transfusion requirement with EPO in...

  4. Preoperative erythropoietin in spine surgery

    Colomina, Maria J.; Bagó, Juan; Pellisé, Ferran; Godet, Carmen; Villanueva, Carlos

    2004-01-01

    Spine surgery may be associated with profuse intraoperative bleeding that often requires blood transfusions. In recent years several techniques have been developed to avoid allogenic transfusions and their potential complications to surgical patients. In this study we review and analyse the role of preoperative recombinant human erythropoietin (rHuEPO) administration in spine surgery as a blood conservation strategy. Between 1998 and 2002, a total of 250 patients scheduled for spine surgery w...

  5. Recombinant erythropoietin in clinical practice

    Ng, T; Marx, G.; Littlewood, T; Macdougall, I

    2003-01-01

    The introduction of recombinant human erythropoietin (RHuEPO) has revolutionised the treatment of patients with anaemia of chronic renal disease. Clinical studies have demonstrated that RHuEPO is also useful in various non-uraemic conditions including haematological and oncological disorders, prematurity, HIV infection, and perioperative therapies. Besides highlighting both the historical and functional aspects of RHuEPO, this review discusses the applications of RHuEPO in clinical practice a...

  6. Monoclonal antibodies to the human insulin receptor that activate glucose transport but not insulin receptor kinase activity

    Forsayeth, J.R.; Caro, J.F.; Sinha, M.K.; Maddux, B.A.; Goldfine, I.D.

    1987-05-01

    Three mouse monoclonal antibodies were produced that reacted with the ..cap alpha.. subunit of the human insulin receptor. All three both immunoprecipitated /sup 125/I-labeled insulin receptors from IM-9 lymphocytes and competitively inhibited /sup 125/I-labeled insulin binding to its receptor. Unlike insulin, the antibodies failed to stimulate receptor autophosphorylation in both intact IM-9 lymphocytes and purified human placental insulin receptors. Moreover, unlike insulin, the antibodies failed to stimulate receptor-mediated phosphorylation of exogenous substrates. However, like insulin, two of the three antibodies stimulated glucose transport in isolated human adipocytes. One antibody, on a molar basis, was as potent as insulin. These studies indicate, therefore, that monoclonal antibodies to the insulin receptor can mimic a major function of insulin without activating receptor kinase activity. They also raise the possibility that certain actions of insulin such as stimulation of glucose transport may not require the activation of receptor kinase activity.

  7. Monoclonal antibodies to the human insulin receptor that activate glucose transport but not insulin receptor kinase activity

    Three mouse monoclonal antibodies were produced that reacted with the α subunit of the human insulin receptor. All three both immunoprecipitated 125I-labeled insulin receptors from IM-9 lymphocytes and competitively inhibited 125I-labeled insulin binding to its receptor. Unlike insulin, the antibodies failed to stimulate receptor autophosphorylation in both intact IM-9 lymphocytes and purified human placental insulin receptors. Moreover, unlike insulin, the antibodies failed to stimulate receptor-mediated phosphorylation of exogenous substrates. However, like insulin, two of the three antibodies stimulated glucose transport in isolated human adipocytes. One antibody, on a molar basis, was as potent as insulin. These studies indicate, therefore, that monoclonal antibodies to the insulin receptor can mimic a major function of insulin without activating receptor kinase activity. They also raise the possibility that certain actions of insulin such as stimulation of glucose transport may not require the activation of receptor kinase activity

  8. EPO's alter ego: erythropoietin has multiple actions.

    Lappin, Terence R; Maxwell, A Peter; Johnston, Patrick G

    2002-01-01

    Many cancer patients suffer from anemia, which has a major detrimental effect on their quality of life. Recombinant human erythropoietin (rHuEPO) is now widely used in cancer patients, as it improves hematocrit, lowers blood transfusion requirements, and improves quality of life. Recent research indicates that EPO has pleiotropic effects on the body well beyond the maintenance of red cell mass, but the mechanisms involved in relieving fatigue and improving quality of life in cancer patients are poorly understood. EPO receptors (EPO-Rs) have been detected in many different cells and tissues, providing evidence for autocrine, paracrine, and endocrine functions of EPO. Apart from its endocrine function, EPO may have a generalized role as an antiapoptotic agent that is associated with enhancement of muscle tone, mucosal status, and gonadal and cognitive function. The recent discovery of EPO-Rs in breast tumor vasculature, while raising important questions about the possible effects of pharmacological doses of rHuEPO on tumor cells, also suggests that the receptors could provide a useful target for drugs attached to EPO. PMID:12456956

  9. Protease activated receptors (PARS) mediation in gyroxin biological activity

    Gyroxin is a serine protease enzyme from the South American rattlesnake (Crotalus durissus terrificus) venom; it is only partially characterized and has multiple activities. Gyroxin induces blood coagulation, blood pressure decrease and a neurotoxic behavior named barrel rotation. The mechanisms involved in this neurotoxic activity are not known. Whereas gyroxin is a member of enzymes with high potential to become a new drug with clinical applications such as thrombin, batroxobin, ancrod, tripsyn and kalicrein, it is important to find out how gyroxin works. The analysis on agarose gel electrophoresis and circular dichroism confirmed the molecules' integrity and purity. The gyroxin intravenous administration in mice proved its neurotoxicity (barrel rotation). In vivo studies employing intravital microscopy proved that gyroxin induces vasodilation with the participation of protease activated receptors (PARs), nitric oxide and Na+K+ATPase. The leukocytes' adherence and rolling counting indicated that gyroxin has no pro inflammatory activity. Gyroxin induced platelet aggregation, which was blocked by inhibitors of PAR1 and PAR4 receptors (SCH 79797 and tcY-NH2, respectively). Finally, it was proved that the gyroxin temporarily alter the permeability of the blood brain barrier (BBB). Our study has shown that both the protease-activated receptors and nitric oxide are mediators involved in the biological activities of gyroxin. (author)

  10. Quantifying Agonist Activity at G Protein-coupled Receptors

    Ehlert, Frederick J.; Suga, Hinako; Griffin, Michael T.

    2011-01-01

    When an agonist activates a population of G protein-coupled receptors (GPCRs), it elicits a signaling pathway that culminates in the response of the cell or tissue. This process can be analyzed at the level of a single receptor, a population of receptors, or a downstream response. Here we describe how to analyze the downstream response to obtain an estimate of the agonist affinity constant for the active state of single receptors.

  11. Cannabinoids go nuclear: evidence for activation of peroxisome proliferator-activated receptors

    O'Sullivan, S E

    2007-01-01

    Cannabinoids act at two classical cannabinoid receptors (CB1 and CB2), a 7TM orphan receptor and the transmitter-gated channel transient receptor potential vanilloid type-1 receptor. Recent evidence also points to cannabinoids acting at members of the nuclear receptor family, peroxisome proliferator-activated receptors (PPARs, with three subtypes α, β (δ) and γ), which regulate cell differentiation and lipid metabolism. Much evidence now suggests that endocannabinoids are natural activators o...

  12. Model for growth hormone receptor activation based on subunit rotation within a receptor dimer

    Brown, Richard J.; Adams, Julian J.; Pelekanos, Rebecca A.; Wan, Yu; McKinstry, William J.; Palethorpe, Kathryn; Seeber, Ruth M.; Monks, Thea A.; Eidne, Karin A.; Parker, Michael W.; Waters, Michael J. (UWA); (St. Vincent); (Queensland)

    2010-07-13

    Growth hormone is believed to activate the growth hormone receptor (GHR) by dimerizing two identical receptor subunits, leading to activation of JAK2 kinase associated with the cytoplasmic domain. However, we have reported previously that dimerization alone is insufficient to activate full-length GHR. By comparing the crystal structure of the liganded and unliganded human GHR extracellular domain, we show here that there is no substantial change in its conformation on ligand binding. However, the receptor can be activated by rotation without ligand by inserting a defined number of alanine residues within the transmembrane domain. Fluorescence resonance energy transfer (FRET), bioluminescence resonance energy transfer (BRET) and coimmunoprecipitation studies suggest that receptor subunits undergo specific transmembrane interactions independent of hormone binding. We propose an activation mechanism involving a relative rotation of subunits within a dimeric receptor as a result of asymmetric placement of the receptor-binding sites on the ligand.

  13. DNA Damage Stress and Inhibition of Jak2-V617F Cause Its Degradation and Synergistically Induce Apoptosis through Activation of GSK3β

    Nagao, Toshikage; Oshikawa, Gaku; Wu, Nan; Kurosu, Tetsuya; Miura, Osamu

    2011-01-01

    The cytoplasmic tyrosine kinase Jak2 plays a crucial role in cytokine receptor signaling in hematopoietic cells. The activated Jak2-V617F mutant is present in most cases of BCR/ABL-negative myeloproliferative neoplasms and constitutively activates downstream signals from homodimeric cytokine receptors, such as the erythropoietin receptor (EpoR). Here we examine the effects of DNA damage stress on Jak2 or Jak2-V617F and on induction of apoptosis in hematopoietic cells. Etoposide or doxorubicin...

  14. Cytoprotective effect of recombinant human erythropoietin produced in transgenic tobacco plants.

    Farooqahmed S Kittur

    Full Text Available Asialo-erythropoietin, a desialylated form of human erythropoietin (EPO lacking hematopoietic activity, is receiving increased attention because of its broader protective effects in preclinical models of tissue injury. However, attempts to translate its protective effects into clinical practice is hampered by unavailability of suitable expression system and its costly and limit production from expensive mammalian cell-made EPO (rhuEPO(M by enzymatic desialylation. In the current study, we took advantage of a plant-based expression system lacking sialylating capacity but possessing an ability to synthesize complex N-glycans to produce cytoprotective recombinant human asialo-rhuEPO. Transgenic tobacco plants expressing asialo-rhuEPO were generated by stably co-expressing human EPO and β1,4-galactosyltransferase (GalT genes under the control of double CaMV 35S and glyceraldehyde-3-phosphate gene (GapC promoters, respectively. Plant-produced asialo-rhuEPO (asialo-rhuEPO(P was purified by immunoaffinity chromatography. Detailed N-glycan analysis using NSI-FTMS and MS/MS revealed that asialo-rhuEPO(P bears paucimannosidic, high mannose-type and complex N-glycans. In vitro cytoprotection assays showed that the asialo-rhuEPO(P (20 U/ml provides 2-fold better cytoprotection (44% to neuronal-like mouse neuroblastoma cells from staurosporine-induced cell death than rhuEPO(M (21%. The cytoprotective effect of the asialo-rhuEPO(P was found to be mediated by receptor-initiated phosphorylation of Janus kinase 2 (JAK2 and suppression of caspase 3 activation. Altogether, these findings demonstrate that plants are a suitable host for producing cytoprotective rhuEPO derivative. In addition, the general advantages of plant-based expression system can be exploited to address the cost and scalability issues related to its production.

  15. Thyroid hormone receptor β mutants: Dominant negative regulators of peroxisome proliferator-activated receptor γ action

    Araki, Osamu; Ying, Hao; Furuya, Fumihiko; Zhu, Xuguang; Cheng, Sheue-yann

    2005-01-01

    Thyroid hormone (T3) and peroxisome proliferators have overlapping metabolic effects in the maintenance of lipid homeostasis. Their actions are mediated by their respective receptors: thyroid hormone receptors (TR) and peroxisome proliferator-activated receptors (PPAR). We recently found that a dominantly negative TRβ mutant (PV) that causes a genetic disease, resistance to thyroid hormone, acts to repress the ligand (troglitazone)-mediated transcriptional activity of PPARγ in cultured thyroi...

  16. ARA 290, a Nonerythropoietic Peptide Engineered from Erythropoietin, Improves Metabolic Control and Neuropathic Symptoms in Patients with Type 2 Diabetes

    Brines, Michael; Dunne, Ann N; van Velzen, Monique; Proto, Paolo L; Ostenson, Claes-Goran; Kirk, Rita I; Petropoulos, Ioannis N; Javed, Saad; Malik, Rayaz A; Cerami, Anthony; Dahan, Albert

    2014-01-01

    Although erythropoietin ameliorates experimental type 2 diabetes with neuropathy, serious side effects limit its potential clinical use. ARA 290, a nonhematopoietic peptide designed from the structure of erythropoietin, interacts selectively with the innate repair receptor that mediates tissue protection. ARA 290 has shown efficacy in preclinical and clinical studies of metabolic control and neuropathy. To evaluate the potential activity of ARA 290 in type 2 diabetes and painful neuropathy, subjects were enrolled in this phase 2 study. ARA 290 (4 mg) or placebo were self-administered subcutaneously daily for 28 d and the subjects followed for an additional month without further treatment. No potential safety issues were identified. Subjects receiving ARA 290 exhibited an improvement in hemoglobin A1c (Hb A1c) and lipid profiles throughout the 56 d observation period. Neuropathic symptoms as assessed by the PainDetect questionnaire improved significantly in the ARA 290 group. Mean corneal nerve fiber density (CNFD) was reduced significantly compared with normal controls and subjects with a mean CNFD >1 standard deviation from normal showed a significant increase in CNFD compared with no change in the placebo group. These observations suggest that ARA 290 may benefit both metabolic control and neuropathy in subjects with type 2 diabetes and deserves continued clinical evaluation. PMID:25387363

  17. The insulin receptor C-terminus is involved in regulation of the receptor kinase activity.

    Kaliman, P; Baron, V; Alengrin, F; Takata, Y; Webster, N J; Olefsky, J M; Van Obberghen, E

    1993-09-21

    During the insulin receptor activation process, ligand binding and autophosphorylation induce two distinct conformational changes in the C-terminal domain of the receptor beta-subunit. To analyze the role of this domain and the involvement of the C-terminal autophosphorylation sites (Tyr1316 and Tyr1322) in receptor activation, we used (i) antipeptide antibodies against three different C-terminal sequences (1270-1281, 1294-1317, and 1309-1326) and (ii) an insulin receptor mutant (Y/F2) where Tyr1316 and Tyr1322 have been replaced by Phe. We show that the autophosphorylation-induced C-terminal conformational change is preserved in the Y/F2 receptor, indicating that this change is not induced by phosphorylation of the C-terminal sites but most likely by phosphorylation of the major sites in the kinase domain (Tyr1146, Tyr1150, and Tyr1151). Binding of antipeptide antibodies to the C-terminal domain modulated (activated or inhibited) both mutant and wild-type receptor-mediated phosphorylation of poly(Glu/Tyr). In contrast to the wild-type receptor, Y/F2 exhibited the same C-terminal configuration before and after insulin binding, evidencing that mutation of Tyr1316 and Tyr1322 introduced conformational changes in the C-terminus. Finally, the mutant receptor was 2-fold more active than the wild-type receptor for poly(Glu/Tyr) phosphorylation. In conclusion, the whole C-terminal region of the insulin receptor beta-subunit is likely to exert a regulatory influence on the receptor kinase activity. Perturbations of the C-terminal region, such as binding of antipeptides or mutation of Tyr1316 and Tyr1322, provoke alterations at the receptor kinase level, leading to activation or inhibition of the enzymic activity. PMID:7690586

  18. The WSXWS motif in cytokine receptors is a molecular switch involved in receptor activation

    Dagil, Robert; Knudsen, Maiken J.; Olsen, Johan Gotthardt;

    2012-01-01

    The prolactin receptor (PRLR) is activated by binding of prolactin in a 2:1 complex, but the activation mechanism is poorly understood. PRLR has a conserved WSXWS motif generic to cytokine class I receptors. We have determined the nuclear magnetic resonance solution structure of the membrane prox...

  19. In vitro neuroprotective action of recombinant rat erythropoietin produced by astrocyte cell lines and comparative studies with erythropoietin produced by Chinese hamster ovary cells

    Masuda, Seiji; Kada, Emi; Nagao, Masaya; Sasaki, Ryuzo

    1999-01-01

    In the central nervous system, astrocytes produce erythropoietin (Epo) and neurons express its receptor. To examine whether or not the brain Epo protects the in vitro cultured neurons from glutamate-induced cell death, we established rat astrocyte cell lines containing the plasmid for production of recombinant rat Epo. Epo partially purified from the culture medium showed a neuroprotective effect similar to that of rat Epo produced by Chinese hamster ovary (CHO) cells. Comparison was made in ...

  20. Recombinant human erythropoietin in sports: a review

    Rafael Maia de Almeida Bento

    2003-06-01

    Full Text Available Erythropoietin is an endogenous hormone of glicoproteic nature secreted by the kidneys and is the main regulator of the erythropoiesis. An alteration in its production generates a disturbance in the plasmatic concentration giving rise to several types of pathologies related to the hematopoietic system. The recombinant forms of erythropoietin have indiscriminately been used by athletes, mainly in endurance sports, by increasing the erythrocytes concentration, generating a better delivery of oxygen to the muscle tissue. The administration of recombinant erythropoietin was prohibited by the International Olympic Committee and its use considered as doping. This review has the intention to describe the physical, biological and pharmacokinetic properties of the endogenous erythropoietin, as well as its recombinant form, describing also its use in sports and the process of searching methodologies for its detection in doping control.

  1. Activation of glucocorticoid receptors increases 5-HT2A receptor levels

    Trajkovska, Viktorija; Kirkegaard, Lisbeth; Krey, Gesa; Marcussen, Anders Bue; Thomsen, Morten Skøtt; Chourbaji, Sabine; Brandwein, Christiane; Ridder, Stephanie; Halldin, Christer; Gass, Peter; Knudsen, Gitte M; Aznar, Susana

    2009-01-01

    Major depression is associated with both dysregulation of the hypothalamic pituitary adrenal axis and serotonergic deficiency, not the least of the 5-HT2A receptor. However, how these phenomena are linked to each other, and whether a low 5-HT2A receptor level is a state or a trait marker of...... depression is unknown. In mice with altered glucocorticoid receptor (GR) expression we investigated 5-HT2A receptor levels by Western blot and 3H-MDL100907 receptor binding. Serotonin fibre density was analyzed by stereological quantification of serotonin transporter immunopositive fibers. To establish an...... effect of GR activation on 5-HT2A levels, mature organotypic hippocampal cultures were exposed to corticosterone with or without GR antagonist mifepristone and mineralocorticoid receptor (MR) antagonist spironolactone. In GR under-expressing mice, hippocampal 5-HT2A receptor protein levels were decreased...

  2. Recent Trends in Erythropoietin-mediated Neuroprotection

    McPherson, Ronald J.; Juul, Sandra E.

    2007-01-01

    Fifteen years of evidence have established that the cytokine erythropoietin offers promise as a treatment for brain injury. In particular, neonatal brain injury may be reduced or prevented by early treatment with recombinant erythropoietin. Extreme prematurity and perinatal asphyxia are common conditions associated with poor neurodevelopmental outcomes including cerebral palsy, mental retardation, hearing or visual impairment, and attention deficit hyperactivity disorder. When high doses of e...

  3. Recombinant human erythropoietin in sports: a review

    Rafael Maia de Almeida Bento; Lúcia Menezes Pinto Damasceno; Francisco Radler Aquino Neto

    2003-01-01

    Erythropoietin is an endogenous hormone of glicoproteic nature secreted by the kidneys and is the main regulator of the erythropoiesis. An alteration in its production generates a disturbance in the plasmatic concentration giving rise to several types of pathologies related to the hematopoietic system. The recombinant forms of erythropoietin have indiscriminately been used by athletes, mainly in endurance sports, by increasing the erythrocytes concentration, generating a better delivery of ox...

  4. Cell death sensitization of leukemia cells by opioid receptor activation

    Friesen, Claudia; Roscher, Mareike; Hormann, Inis; Fichtner, Iduna; Alt, Andreas; Hilger, Ralf A.; Debatin, Klaus-Michael; Miltner, Erich

    2013-01-01

    Cyclic AMP (cAMP) regulates a number of cellular processes and modulates cell death induction. cAMP levels are altered upon stimulation of specific G-protein-coupled receptors inhibiting or activating adenylyl cyclases. Opioid receptor stimulation can activate inhibitory Gi-proteins which in turn block adenylyl cyclase activity reducing cAMP. Opioids such as D,L-methadone induce cell death in leukemia cells. However, the mechanism how opioids trigger apoptosis and activate caspases in leukemia cells is not understood. In this study, we demonstrate that downregulation of cAMP induced by opioid receptor activation using the opioid D,L-methadone kills and sensitizes leukemia cells for doxorubicin treatment. Enhancing cAMP levels by blocking opioid-receptor signaling strongly reduced D,L-methadone-induced apoptosis, caspase activation and doxorubicin-sensitivity. Induction of cell death in leukemia cells by activation of opioid receptors using the opioid D,L-methadone depends on critical levels of opioid receptor expression on the cell surface. Doxorubicin increased opioid receptor expression in leukemia cells. In addition, the opioid D,L-methadone increased doxorubicin uptake and decreased doxorubicin efflux in leukemia cells, suggesting that the opioid D,L-methadone as well as doxorubicin mutually increase their cytotoxic potential. Furthermore, we found that opioid receptor activation using D,L-methadone alone or in addition to doxorubicin inhibits tumor growth significantly in vivo. These results demonstrate that opioid receptor activation via triggering the downregulation of cAMP induces apoptosis, activates caspases and sensitizes leukemia cells for doxorubicin treatment. Hence, opioid receptor activation seems to be a promising strategy to improve anticancer therapies. PMID:23633472

  5. Recombinant Human Erythropoietin Protects Myocardial Cells from Apoptosis via the Janus-Activated Kinase 2/Signal Transducer and Activator of Transcription 5 Pathway in Rats with Epilepsy

    Bao-Xin Ma, MD

    2015-12-01

    Conclusions: These results indicate that myocardial cell apoptosis may contribute to myocardial injury in epilepsy. EPO protects myocardial cells from apoptosis via the JAK2/STAT5 pathway in rats with experimental epilepsy, whereas CEPO exerts antiapoptotic activity perhaps via a pathway independent of JAK2/STAT5 signaling.

  6. Comparison of the activation kinetics of the M3 acetylcholine receptor and a constitutively active mutant receptor in living cells.

    Hoffmann, Carsten; Nuber, Susanne; Zabel, Ulrike; Ziegler, Nicole; Winkler, Christiane; Hein, Peter; Berlot, Catherine H; Bünemann, Moritz; Lohse, Martin J

    2012-08-01

    Activation of G-protein-coupled receptors is the first step of the signaling cascade triggered by binding of an agonist. Here we compare the activation kinetics of the G(q)-coupled M(3) acetylcholine receptor (M(3)-AChR) with that of a constitutively active mutant receptor (M(3)-AChR-N514Y) using M(3)-AChR constructs that report receptor activation by changes in the fluorescence resonance energy transfer (FRET) signal. We observed a leftward shift in the concentration-dependent FRET response for acetylcholine and carbachol with M(3)-AChR-N514Y. Consistent with this result, at submaximal agonist concentrations, the activation kinetics of M(3)-AChR-N514Y were significantly faster, whereas at maximal agonist concentrations the kinetics of receptor activation were identical. Receptor deactivation was significantly faster with carbachol than with acetylcholine and was significantly delayed by the N514Y mutation. Receptor-G-protein interaction was measured by FRET between M(3)-AChR-yellow fluorescent protein (YFP) and cyan fluorescent protein (CFP)-Gγ(2). Agonist-induced receptor-G-protein coupling was of a time scale similar to that of receptor activation. As observed for receptor deactivation, receptor-G-protein dissociation was slower for acetylcholine than that for carbachol. Acetylcholine-stimulated increases in receptor-G-protein coupling of M(3)-AChR-N514Y reached only 12% of that of M(3)-AChR and thus cannot be kinetically analyzed. G-protein activation was measured using YFP-tagged Gα(q) and CFP-tagged Gγ(2). Activation of G(q) was significantly slower than receptor activation and indistinguishable for the two agonists. However, G(q) deactivation was significantly prolonged for acetylcholine compared with that for carbachol. Consistent with decreased agonist-stimulated coupling to G(q), agonist-stimulated G(q) activation by M(3)-AChR-N514Y was not detected. Taken together, these results indicate that the N514Y mutation produces constitutive activation of M(3

  7. The Orphan Nuclear Receptor TR4 Is a Vitamin A-activated Nuclear Receptor

    Zhou, X. Edward; Suino-Powell, Kelly M.; Xu, Yong; Chan, Cee-Wah; Tanabe, Osamu; Kruse, Schoen W.; Reynolds, Ross; Engel, James Douglas; Xu, H. Eric (Michigan-Med); (Van Andel)

    2015-11-30

    Testicular receptors 2 and 4 (TR2/4) constitute a subgroup of orphan nuclear receptors that play important roles in spermatogenesis, lipid and lipoprotein regulation, and the development of the central nervous system. Currently, little is known about the structural features and the ligand regulation of these receptors. Here we report the crystal structure of the ligand-free TR4 ligand binding domain, which reveals an autorepressed conformation. The ligand binding pocket of TR4 is filled by the C-terminal half of helix 10, and the cofactor binding site is occupied by the AF-2 helix, thus preventing ligand-independent activation of the receptor. However, TR4 exhibits constitutive transcriptional activity on multiple promoters, which can be further potentiated by nuclear receptor coactivators. Mutations designed to disrupt cofactor binding, dimerization, or ligand binding substantially reduce the transcriptional activity of this receptor. Importantly, both retinol and retinoic acid are able to promote TR4 to recruit coactivators and to activate a TR4-regulated reporter. These findings demonstrate that TR4 is a ligand-regulated nuclear receptor and suggest that retinoids might have a much wider regulatory role via activation of orphan receptors such as TR4.

  8. The anemia of microgravity and recumbency. Role of sympathetic neural control of erythropoietin production

    Robertson, David; Krantz, Sanford B.; Biaggioni, Italo

    We hypothesize that reduced sympathetic stimulation of erythropoietin production may maintain the anemia which develops in virtually all space travellers. We tested this hypothesis in a human model of reduced sympathetic activity. Thirty-three patients with the Bradbury-Eggleston syndrome were divided into three groups according to their hemoglobin (Hgb) level. Patients with low Hgb had lower upright norepinephrine and lower upright renin. Patients with anemia also had inappropriately low plasma erythropoietin levels. We administered recombinant erythropoietin (Epogen) 25-50 units/kg s.c. 3 times per week and found that the anemia seen in autonomic failure could be reversed by this treatment. These results support the hypothesis that erythropoiesis is modulated by the sympathetic nervous system and that such mechanisms may also operate in the microgravity environment where sympathetic activity is reduced.

  9. Incorporation of Ortho- and Meta-Tyrosine Into Cellular Proteins Leads to Erythropoietin-Resistance in an Erythroid Cell Line

    Esztella Mikolás

    2014-04-01

    Full Text Available Background/Aims: Erythropoietin-resistance is an unsolved concern in the treatment of renal anaemia. We aimed to investigate the possible role of ortho- and meta-tyrosine - the hydroxyl free radical products of L-phenylalanine - in the development of erythropoietin-resistance. Methods: TF-1 erythroblast cell line was used. Cell concentration was determined on day 1; 2 and 3 by two independent observers simultaneously in Bürker cell counting chambers. Protein concentration was determined with colorimetric method. Para-, ortho- and meta-tyrosine levels were measured using reverse phase-HPLC with fluorescence detection. Using Western blot method activating phosphorylation of STAT5 and ERK1/2 were investigated. Results: We found a time- and concentration-dependent decrease of erythropoietin-induced proliferative activity in case of ortho- and meta-tyrosine treated TF-1 erythroblasts, compared to the para-tyrosine cultured cells. Decreased erythropoietin-response could be regained with a competitive dose of para-tyrosine. Proteins of erythroblasts treated by ortho- or meta-tyrosine had lower para-tyrosine and higher ortho- or meta-tyrosine content. Activating phosphorylation of ERK and STAT5 due to erythropoietin was practically prevented by ortho- or meta-tyrosine treatment. Conclusion: According to this study elevated ortho- and meta-tyrosine content of erythroblasts may lead to the dysfunction of intracellular signaling, resulting in erythropoietin-hyporesponsiveness.

  10. Kit transduced signals counteract erythroid maturation by MAPK-dependent modulation of erythropoietin signaling and apoptosis induction in mouse fetal liver.

    Haas, N; Riedt, T; Labbaf, Z; Baßler, K; Gergis, D; Fröhlich, H; Gütgemann, I; Janzen, V; Schorle, H

    2015-05-01

    Signaling by the stem cell factor receptor Kit in hematopoietic stem and progenitor cells is functionally associated with the regulation of cellular proliferation, differentiation and survival. Expression of the receptor is downregulated upon terminal differentiation in most lineages, including red blood cell terminal maturation, suggesting that omission of Kit transduced signals is a prerequisite for the differentiation process to occur. However, the molecular mechanisms by which Kit signaling preserves the undifferentiated state of progenitor cells are not yet characterized in detail. In this study, we generated a mouse model for inducible expression of a Kit receptor carrying an activating mutation and studied its effects on fetal liver hematopoiesis. We found that sustained Kit signaling leads to expansion of erythroid precursors and interferes with terminal maturation beyond the erythroblast stage. Primary KIT(D816V) erythroblasts stimulated to differentiate fail to exit cell cycle and show elevated rates of apoptosis because of insufficient induction of survival factors. They further retain expression of progenitor cell associated factors c-Myc, c-Myb and GATA-2 and inefficiently upregulate erythroid transcription factors GATA-1, Klf1 and Tal1. In KIT(D816V) erythroblasts we found constitutive activation of the mitogen-activated protein kinase (MAPK) pathway, elevated expression of the src kinase family member Lyn and impaired Akt activation in response to erythropoietin. We demonstrate that the block in differentiation is partially rescued by MAPK inhibition, and completely rescued by the multikinase inhibitor Dasatinib. These results show that a crosstalk between Kit and erythropoietin receptor signaling cascades exists and that continuous Kit signaling, partly mediated by the MAPK pathway, interferes with this crosstalk. PMID:25323585

  11. Continuous production of erythropoietin by an established human renal carcinoma cell line: development of the cell line

    Establishment of a stable, transformed human renal carcinoma cell line that produces erythropoietin in vitro and has maintained this function continuously since 1981 and for > 150 passages in monolayer culture was accomplished by transplantation of human renal clear cell carcinoma tissue from a patient with erythrocytosis into an immunosuppressed athymic mouse. In addition to its immunocrossreactivity with native human urinary erythropoietin, the tumor erythropoietin demonstrates biological activity in the in vitro mouse erythroid colony-forming unit assay and in tumor-bearing nude mice. The cloned renal carcinoma cell line has an abnormal human karyotype and has ultrastructural features characteristic of human renal clear cell carcinoma. This cell line provides a reproducible model system for the production of an erythropoietin-like material and for the study of its synthesis and secretion

  12. The insulin receptor activation process involves localized conformational changes.

    Baron, V; Kaliman, P; Gautier, N; Van Obberghen, E

    1992-11-15

    The molecular process by which insulin binding to the receptor alpha-subunit induces activation of the receptor beta-subunit with ensuing substrate phosphorylation remains unclear. In this study, we aimed at approaching this molecular mechanism of signal transduction and at delineating the cytoplasmic domains implied in this process. To do this, we used antipeptide antibodies to the following sequences of the receptor beta-subunit: (i) positions 962-972 in the juxtamembrane domain, (ii) positions 1247-1261 at the end of the kinase domain, and (iii) positions 1294-1317 and (iv) positions 1309-1326, both in the receptor C terminus. We have previously shown that insulin binding to its receptor induces a conformational change in the beta-subunit C terminus. Here, we demonstrate that receptor autophosphorylation induces an additional conformational change. This process appears to be distinct from the one produced by ligand binding and can be detected in at least three different beta-subunit regions: the juxtamembrane domain, the kinase domain, and the C terminus. Hence, the cytoplasmic part of the receptor beta-subunit appears to undergo an extended conformational change upon autophosphorylation. By contrast, the insulin-induced change does not affect the juxtamembrane domain 962-972 nor the kinase domain 1247-1261 and may be limited to the receptor C terminus. Further, we show that the hormone-dependent conformational change is maintained in a kinase-deficient receptor due to a mutation at lysine 1018. Therefore, during receptor activation, the ligand-induced change could precede ATP binding and receptor autophosphorylation. We propose that insulin binding leads to a transient receptor form that may allow ATP binding and, subsequently, autophosphorylation. The second conformational change could unmask substrate-binding sites and stabilize the receptor in an active conformation. PMID:1331080

  13. Interaction of chemokines with their receptors--from initial chemokine binding to receptor activating steps

    Thiele, Stefanie; Rosenkilde, Mette Marie

    2014-01-01

    The human chemokine system comprises 19 seven-transmembrane helix (7TM) receptors and 45 endogenous chemokines that often interact with each other in a promiscuous manner. Due to the chemokine system's primary function in leukocyte migration, it has a central role in immune homeostasis and...... interactions possibly occur, resulting in a multi-step process, as recently proposed for other 7TM receptors. Overall, the N-terminus of chemokine receptors is pivotal for binding of all chemokines. During receptor activation, differences between the two major chemokine subgroups occur, as CC-chemokines mainly...

  14. Chronic hyperammonemia induces tonic activation of NMDA receptors in cerebellum.

    ElMlili, Nisrin; Boix, Jordi; Ahabrach, Hanan; Rodrigo, Regina; Errami, Mohammed; Felipo, Vicente

    2010-02-01

    Reduced function of the glutamate--nitric oxide (NO)--cGMP pathway is responsible for some cognitive alterations in rats with hyperammonemia and hepatic encephalopathy. Hyperammonemia impairs the pathway in cerebellum by increasing neuronal nitric oxide synthase (nNOS) phosphorylation in Ser847 by calcium-calmodulin-dependent protein kinase II (CaMKII), reducing nNOS activity, and by reducing nNOS amount in synaptic membranes, which reduces its activation following NMDA receptors activation. The reason for increased CaMKII activity in hyperammonemia remains unknown. We hypothesized that it would be as a result of increased tonic activation of NMDA receptors. The aims of this work were to assess: (i) whether tonic NMDA activation receptors is increased in cerebellum in chronic hyperammonemia in vivo; and (ii) whether this tonic activation is responsible for increased CaMKII activity and reduced activity of nNOS and of the glutamate--NO--cGMP pathway. Blocking NMDA receptors with MK-801 increases cGMP and NO metabolites in cerebellum in vivo and in slices from hyperammonemic rats. This is because of reduced phosphorylation and activity of CaMKII, leading to normalization of nNOS phosphorylation and activity. MK-801 also increases nNOS in synaptic membranes and reduces it in cytosol. This indicates that hyperammonemia increases tonic activation of NMDA receptors leading to reduced activity of nNOS and of the glutamate--NO--cGMP pathway. PMID:20002515

  15. Redefining the concept of protease-activated receptors: cathepsin S evokes itch via activation of Mrgprs

    Reddy, Vemuri B.; Sun, Shuohao; Azimi, Ehsan; Elmariah, Sarina B.; Dong, Xinzhong; Lerner, Ethan A.

    2015-01-01

    Sensory neurons expressing Mas-related G protein coupled receptors (Mrgprs) mediate histamine-independent itch. We show that the cysteine protease cathepsin S activates MrgprC11 and evokes receptor-dependent scratching in mice. In contrast to its activation of conventional protease-activated receptors, cathepsin S mediated activation of MrgprC11 did not involve the generation of a tethered ligand. We demonstrate further that different cysteine proteases selectively activate specific mouse and...

  16. Recombinant human erythropoietin (rHuEPO): more than just the correction of uremic anemia.

    Buemi, Michele; Aloisi, Carmela; Cavallaro, Emanuela; Corica, Francesco; Floccari, Fulvio; Grasso, Giovanni; Lasco, Antonino; Pettinato, Giuseppina; Ruello, Antonella; Sturiale, Alessio; Frisina, Nicola

    2002-01-01

    Hematopoiesis is controlled by numerous interdependent humoral and endocrine factors. Erythropoietin (EPO), a hydrophobic sialoglycoproteic hormone, plays a crucial role in the regulation of hematopoiesis, and induces proliferation, maturation and differentiation of the erythroid cell line precursors. Thanks to recombinant DNA techniques, different recombinant hormones can now be produced at low cost and in large amounts. This has led to greater understanding of the pathophysiological factors regulating hematopoiesis. This in turn, hasprompted the search for new therapeutic approaches. EPO might also be used to treat patients with different types of anemia: uremics, newborns, patients with anemia from cancer or myeloproliferative disease, thalassemia, bone marrow transplants, chronic infectious diseases. Besides erythroid cells, EPO affects other blood cell lines, such as myeloid cells, lymphocytes and megakaryocytes. It can also enhance polymorphonuclear cell phagocytosis and reduce macrophage activation, thus modulating the inflammatory process. Hematopoietic and endothelial cells probably have the same origin, and the discovery of eyrthropoietin receptors also on mesangial, myocardial and smooth muscle cells has prompted research into the non-erythropoietic function of the hormone. EPO has an important, direct, hemodynamic and vasoactive effect, which does not depend only on an increase in hematocrit and viscosity. Moreover, EPO and its receptors have been found in the brain, suggesting a role in preventing neuronal death. Finally, the recently discovered interaction between EPO and vascular endothelial growth factor (VEGF), and the ability of EPO to stimulate endothelial cell mitosis and motility may be of importance in neovascularization and wound healing. PMID:12018644

  17. Human receptor activation by aroclor 1260, a polychlorinated biphenyl mixture.

    Wahlang, Banrida; Falkner, K Cameron; Clair, Heather B; Al-Eryani, Laila; Prough, Russell A; States, J Christopher; Coslo, Denise M; Omiecinski, Curtis J; Cave, Matthew C

    2014-08-01

    Polychlorinated biphenyls (PCBs) are persistent environmental toxicants, present in 100% of U.S. adults and dose-dependently associated with obesity and non-alcoholic fatty liver disease (NAFLD). PCBs are predicted to interact with receptors previously implicated in xenobiotic/energy metabolism and NAFLD. These receptors include the aryl hydrocarbon receptor (AhR), pregnane xenobiotic receptor (PXR), constitutive androstane receptor (CAR), peroxisome proliferator-activated receptors (PPARs), liver-X-receptor (LXRα), and farnesoid-X-receptor (FXR). This study evaluates Aroclor 1260, a PCB mixture with congener composition mimicking that of human adipose tissue, and selected congeners, as potential ligands for these receptors utilizing human hepatoma-derived (HepG2) and primate-derived (COS-1) cell lines, and primary human hepatocytes. Aroclor 1260 (20 μg/ml) activated AhR, and PCB 126, a minor component, was a potent inducer. Aroclor 1260 activated PXR in a simple concentration-dependent manner at concentrations ≥10 μg/ml. Among the congeners tested, PCBs 138, 149, 151, 174, 183, 187, and 196 activated PXR. Aroclor 1260 activated CAR2 and CAR3 variants at lower concentrations and antagonize CAR2 activation by the CAR agonist, CITCO, at higher concentrations (≥20 μg/ml). Additionally, Aroclor 1260 induced CYP2B6 in primary hepatocytes. At subtoxic doses, Aroclor 1260 did not activate LXR or FXR and had no effect on LXR- or FXR-dependent induction by the agonists T0901317 or GW4064, respectively. Aroclor 1260 (20 μg/ml) suppressed PPARα activation by the agonist nafenopin, although none of the congeners tested demonstrated significant inhibition. The results suggest that Aroclor 1260 is a human AhR, PXR and CAR3 agonist, a mixed agonist/antagonist for CAR2, and an antagonist for human PPARα. PMID:24812009

  18. Tonic activation of presynaptic GABAB receptors on rat pallidosubthalamic terminals

    Lei CHEN; Wing-ho YUNG

    2005-01-01

    Aim: The subthalamic nucleus plays a critical role in the regulation of movement,and abnormal activity of its neurons is associated with some basal ganglia motor symptoms. We examined the presence of functional presynaptic GABAB receptors on pallidosubthalamic terminals and tested whether they were tonically active in the in vitro subthalamic slices. Methods: Whole-cell patch-clamp recordings were applied to acutely prepared rat subthalamic nucleus slices. The effects of specific GABAB agonist and antagonist on action potential-independent inhibitory postsynapfic currents (IPSCs), as well as holding current, were examined.Results: Superfusion of baclofen, a GABAB receptor agonist, significantly reduced the frequency of GABAA receptor-mediated miniature IPSCs (mIPSCs), in a Cd2+-sensitive manner, with no effect on the amplitude, indicating presynaptic inhibition on GABA release. In addition, baclofen induced a weak outward current only in a minority of subthalamic neurons. Both the pre- and post-synaptic effects of baclofen were prevented by the specific GABAB receptor antagonist,CGP55845. Furthermore, CGP55845 alone increased the frequency of mIPSCs,but had no effect on the holding current. Conclusion: These findings suggest the functional dominance of presynaptic GABAB receptors on the pallidosubthalamic terminals over the postsynaptic GABAB receptors on subthalamic neurons.Furthermore, the presynaptic, but not the postsynaptic, GABAB receptors are tonically active, suggesting that the presynaptic GABAB receptors in the subthalamic nucleus are potential therapeutic target for the treatment of Parkinson disease.

  19. Skeletal muscle alterations and exercise performance decrease in erythropoietin-deficient mice: a comparative study

    Mille-Hamard Laurence; Billat Veronique L; Henry Elodie; Bonnamy Blandine; Joly Florence; Benech Philippe; Barrey Eric

    2012-01-01

    Abstract Background Erythropoietin (EPO) is known to improve exercise performance by increasing oxygen blood transport and thus inducing a higher maximum oxygen uptake (VO2max). Furthermore, treatment with (or overexpression of) EPO induces protective effects in several tissues, including the myocardium. However, it is not known whether EPO exerts this protective effect when present at physiological levels. Given that EPO receptors have been identified in skeletal muscle, we hypothesized that...

  20. Erythropoietin binding sites in human foetal tissues

    Using 125I labelled recombinant DNA human erythropoietin (EP), we have explored the presence and properties of EP binding sites in foetal human tissues. The EP binding site is present in the foetal liver already during the first trimester of pregnancy. The binding site has a equilibrium association constant of 4.1-6.2 x 109l/mol and is specific for EP. The cross-reactivities of FSH, TSH, hCG, insulin and renin substrate were less than 0.01%. The EP binding capacity of foetal liver was 5.4-16 fmol/mg membrane protein. In foetal lung tissue, a slight EP binding activity was observed, whereas foetal spleen, muscle, brain, thyroid and placental tissues were virtually devoid of EP binding capacity. The same level of binding was reached at 37 deg. C in 1 h and at 4 deg. C in 24 h. The binding was pH-dependent with maximal specific binding at pH 7.7. SDS-PAGE gel electrophoresis analysis of covalently cross-linked 125I-EP to foetal liver membranes suggested that the EP binding site was composed of two subunits with an apparent mol wt of 41000 and 86000 dalton, respectively. (author)

  1. Erythropoietin upregulation in pulmonary arterial hypertension.

    Karamanian, Vanesa A; Harhay, Michael; Grant, Gregory R; Palevsky, Harold I; Grizzle, William E; Zamanian, Roham T; Ihida-Stansbury, Kaori; Taichman, Darren B; Kawut, Steven M; Jones, Peter L

    2014-06-01

    The pathophysiologic alterations of patients with pulmonary arterial hypertension (PAH) are diverse. We aimed to determine novel pathogenic pathways from circulating proteins in patients with PAH. Multianalyte profiling (MAP) was used to measure 90 specifically selected antigens in the plasma of 113 PAH patients and 51 control patients. Erythropoietin (EPO) functional activity was assessed via in vitro pulmonary artery endothelial cell networking and smooth muscle cell proliferation assays. Fifty-eight patients had idiopathic PAH, whereas 55 had other forms of PAH; 5 had heritable PAH, 18 had connective tissue disease (15 with scleroderma and 3 with lupus erythematosis), 13 had portopulmonary hypertension, 6 had PAH associated with drugs or toxins, and 5 had congenital heart disease. The plasma-antigen profile of PAH revealed increased levels of several novel biomarkers, including EPO. Immune quantitative and histochemical studies revealed that EPO not only was significantly elevated in the plasma of PAH patients but also promoted pulmonary artery endothelial cell network formation and smooth muscle cell proliferation. MAP is a hypothesis-generating approach to identifying novel pathophysiologic pathways in PAH. EPO is upregulated in the circulation and lungs of patients with PAH and may affect endothelial and smooth muscle cell proliferation. PMID:25006446

  2. Erythropoietin binding sites in human foetal tissues

    Pekonen, F.; Rosenloef, K.; Rutanen, E.-M.

    1987-01-01

    Using /sup 125/I labelled recombinant DNA human erythropoietin (EP), we have explored the presence and properties of EP binding sites in foetal human tissues. The EP binding site is present in the foetal liver already during the first trimester of pregnancy. The binding site has a equilibrium association constant of 4.1-6.2 x 10/sup 9/l/mol and is specific for EP. The cross-reactivities of FSH, TSH, hCG, insulin and renin substrate were less than 0.01%. The EP binding capacity of foetal liver was 5.4-16 fmol/mg membrane protein. In foetal lung tissue, a slight EP binding activity was observed, whereas foetal spleen, muscle, brain, thyroid and placental tissues were virtually devoid of EP binding capacity. The same level of binding was reached at 37 deg. C in 1 h and at 4 deg. C in 24 h. The binding was pH-dependent with maximal specific binding at pH 7.7. SDS-PAGE gel electrophoresis analysis of covalently cross-linked /sup 125/I-EP to foetal liver membranes suggested that the EP binding site was composed of two subunits with an apparent mol wt of 41000 and 86000 dalton, respectively.

  3. Hemopoietic cell precursor responses to erythropoietin in plasma clot cultures

    Kennedy, W.L.

    1979-01-01

    The time dependence of the response of mouse bone marrow cells to erythropoietin (Ep) in vitro was studied. Experiments include studies on the Ep response of marrow cells from normal, plethoric, or bled mice. Results with normal marrow reveal: (1) Not all erythroid precursors (CFU-E) are alike in their response to Ep. A significant number of the precursors develop to a mature erythroid colony after very short Ep exposures, but they account for only approx. 13% of the total colonies generated when Ep is active for 48 hrs. If Ep is active more than 6 hrs, a second population of erythroid colonies emerges at a nearly constant rate until the end of the culture. Full erythroid colony production requires prolonged exposure to erythropoietin. (2) The longer erythropoietin is actively present, the larger the number of erythroid colonies that reach 17 cells or more. Two distinct populations of immediate erythroid precursors are also present in marrow from plethoric mice. In these mice, total colony numbers are equal to or below those obtained from normal mice. However, the population of fast-responding CFU-E is consistently decreased to 10 to 20% of that found in normal marrow. The remaining colonies are formed from plethoric marrow at a rate equal to normal marrow. With increasing Ep exposures, the number of large colonies produced increases. From the marrow of bled mice, total erythroid colony production is equal to or above that of normal marrow. Two populations of colony-forming cells are again evident, with the fast-responding CFU-E being below normal levels. The lack of colonies from this group was compensated in bled mice by rapid colony production in the second population. A real increase in numbers of precursors present in this pool increased the rate of colony production in culture to twice that of normal marrow. The number of large colonies obtained from bled mice was again increased as the Ep exposure was lengthened. (ERB)

  4. Helix 11 Dynamics is Critical for Constitutive Androstane Receptor Activity

    Wright, Edward; Busby, Scott A.; Wisecarver, Sarah; Vincent, Jeremy; Griffin, Patrick R.; Fernandez, Elias J.

    2011-01-01

    The constitutive androstane receptor (CAR) transactivation can occur in the absence of exogenous ligand and this activity is enhanced by agonists TCPOBOP and meclizine. We use biophysical and cell-based assays to show that increased activity of CAR(TCPOBOP) relative to CAR(meclizine) corresponds to a higher affinity of CAR(TCPOBOP) for the steroid receptor coactivator-1. Additionally, steady-state fluorescence spectra suggest conformational differences between CAR(TCPOBOP):RXR and CAR(meclizi...

  5. Heterodimeric interaction between retinoid X receptor alpha and orphan nuclear receptor OR1 reveals dimerization-induced activation as a novel mechanism of nuclear receptor activation.

    Wiebel, F F; Gustafsson, J.A.

    1997-01-01

    OR1 is a member of the steroid/thyroid hormone nuclear receptor superfamily which has been described to mediate transcriptional responses to retinoids and oxysterols. On a DR4 response element, an OR1 heterodimer with the nuclear receptor retinoid X receptor alpha (RXR alpha) has been described to convey transcriptional activation in both the absence and presence of the RXR ligand 9-cis retinoic acid, the mechanisms of which have remained unclear. Here, we dissect the effects of RXR alpha and...

  6. Retinoic Acid-mediated Nuclear Receptor Activation and Hepatocyte Proliferation

    Bushue, Nathan; Wan, Yu-Jui Yvonne

    2016-01-01

    Due to their well-known differentiation and apoptosis-inducing abilities, retinoic acid (RA) and its analogs have strong anti-cancer efficacy in human cancers. However, in vivo RA is a liver mitogen. While speculation has persisted that RA-mediated signaling is likely involved in hepatocyte proliferation during liver regeneration, direct evidence is still required. Findings in support of this proposition include observations that a release of retinyl palmitate (the precursor of RA) occurs in liver stellate cells following liver injury. Nevertheless, the biological action of this released vitamin A is virtually unknown. More likely is that the released vitamin A is converted to RA, the biological form, and then bound to a specific receptor (retinoid x receptor; RXRα), which is most abundantly expressed in the liver. Considering the mitogenic effects of RA, the RA-activated RXRα would likely then influence hepatocyte proliferation and liver tissue repair. At present, the mechanism by which RA stimulates hepatocyte proliferation is largely unknown. This review summarizes the activation of nuclear receptors (peroxisome proliferator activated receptor-α, pregnane x receptor, constitutive androstane receptor, and farnesoid x receptor) in an RXRα dependent manner to induce hepatocyte proliferation, providing a link between RA and its proliferative role.

  7. Environmental polycyclic aromatic hydrocarbons affect androgen receptor activation in vitro

    Vinggaard, Anne Marie; Hnida, Christina; Larsen, John Christian

    2000-01-01

    of certain PAHs to activate the Ah receptor was assessed in H4IIE liver cancer cells, stably transfected with a luciferase reporter gene system. The positive control 2, 3,7, 8-tetrachlorodibenzodioxin (TCDD) caused a 13-14-fold induction of luciferase activity reaching maximum activity at 0.1 nM. DB...

  8. Environmental polycyclic aromatic hydrocarbons affect androgen receptor activation in vitro

    Vinggaard, Anne Marie; Hnida, Christina; Larsen, John Christian

    of certain PAHs to activate the Ah receptor was assessed in H4IIE liver cancer cells, stably transfected with a luciferase reporter gene system. The positive control 2, 3,7, 8-tetrachlorodibenzodioxin (TCDD) caused a 13-14-fold induction of luciferase activity reaching maximum activity at 0.1 nM. DB...

  9. Modulation of β-catenin signaling by glucagon receptor activation.

    Jiyuan Ke

    Full Text Available The glucagon receptor (GCGR is a member of the class B G protein-coupled receptor family. Activation of GCGR by glucagon leads to increased glucose production by the liver. Thus, glucagon is a key component of glucose homeostasis by counteracting the effect of insulin. In this report, we found that in addition to activation of the classic cAMP/protein kinase A (PKA pathway, activation of GCGR also induced β-catenin stabilization and activated β-catenin-mediated transcription. Activation of β-catenin signaling was PKA-dependent, consistent with previous reports on the parathyroid hormone receptor type 1 (PTH1R and glucagon-like peptide 1 (GLP-1R receptors. Since low-density-lipoprotein receptor-related protein 5 (Lrp5 is an essential co-receptor required for Wnt protein mediated β-catenin signaling, we examined the role of Lrp5 in glucagon-induced β-catenin signaling. Cotransfection with Lrp5 enhanced the glucagon-induced β-catenin stabilization and TCF promoter-mediated transcription. Inhibiting Lrp5/6 function using Dickkopf-1(DKK1 or by expression of the Lrp5 extracellular domain blocked glucagon-induced β-catenin signaling. Furthermore, we showed that Lrp5 physically interacted with GCGR by immunoprecipitation and bioluminescence resonance energy transfer assays. Together, these results reveal an unexpected crosstalk between glucagon and β-catenin signaling, and may help to explain the metabolic phenotypes of Lrp5/6 mutations.

  10. Cloning, constitutive activity and expression profiling of two receptors related to relaxin receptors in Drosophila melanogaster.

    Van Hiel, Matthias B; Vandersmissen, Hans Peter; Proost, Paul; Vanden Broeck, Jozef

    2015-06-01

    Leucine-rich repeat containing G protein-coupled receptors (LGRs) comprise a cluster of transmembrane proteins, characterized by the presence of a large N-terminal extracellular domain. This receptor group can be classified into three subtypes. Belonging to the subtype C LGRs are the mammalian relaxin receptors LGR7 (RXFP1) and LGR8 (RXFP2), which mediate important reproductive and other processes. We identified two related receptors in the genome of the fruit fly and cloned their open reading frames into an expression vector. Interestingly, dLGR3 demonstrated constitutive activity at very low doses of transfected plasmid, whereas dLGR4 did not show any basal activity. Both receptors exhibited a similar expression pattern during development, with relatively high transcript levels during the first larval stage. In addition, both receptors displayed higher expression in male adult flies as compared to female flies. Analysis of the tissue distribution of both receptor transcripts revealed a high expression of dLGR3 in the female fat body, while the expression of dLGR4 peaked in the midgut of both the wandering and adult stage. PMID:25064813

  11. DMPD: Receptor tyrosine kinases and the regulation of macrophage activation. [Dynamic Macrophage Pathway CSML Database

    Full Text Available 14726496 Receptor tyrosine kinases and the regulation of macrophage activation. Cor...(.csml) Show Receptor tyrosine kinases and the regulation of macrophage activation. PubmedID 14726496 Title Receptor tyrosine kinases

  12. Nuclear receptor corepressor-dependent repression of peroxisome-proliferator-activated receptor delta-mediated transactivation

    Krogsdam, Anne-M; Nielsen, Curt A F; Neve, Søren;

    2002-01-01

    delta-RXR alpha heterodimer bound to an acyl-CoA oxidase (ACO)-type peroxisome-proliferator response element recruited a glutathione S-transferase-NCoR fusion protein in a ligand-independent manner. Contrasting with most other nuclear receptors, PPAR delta was found to interact equally well......The nuclear receptor corepressor (NCoR) was isolated as a peroxisome-proliferator-activated receptor (PPAR) delta interacting protein using the yeast two-hybrid system. NCoR interacted strongly with the ligand-binding domain of PPAR delta, whereas interactions with the ligand-binding domains...

  13. Transcriptional activation of nuclear estrogen receptor and progesterone receptor and its regulation.

    Xin, Qi-Liang; Qiu, Jing-Tao; Cui, Sheng; Xia, Guo-Liang; Wang, Hai-Bin

    2016-08-25

    Estrogen receptor (ER) and progesterone receptor (PR) are two important members of steroid receptors family, an evolutionarily conserved family of transcription factors. Upon binding to their ligands, ER and PR enter cell nucleus to interact with specific DNA element in the context of chromatin to initiate the transcription of diverse target genes, which largely depends on the timely recruitment of a wide range of cofactors. Moreover, the interactions between steroid hormones and their respective receptors also trigger post-translational modifications on these receptors to fine-tune their transcriptional activities. Besides the well-known phosphorylation modifications on tyrosine and serine/threonine residues, recent studies have identified several other covalent modifications, such as ubiquitylation and sumoylation. These post-translational modifications of steroid receptors affect its stability, subcellular localization, and/or cofactor recruitment; eventually influence the duration and extent of transcriptional activation. This review is to focus on the recent research progress on the transcriptional activation of nuclear ER and PR as well as their physiological functions in early pregnancy, which may help us to better understand related female reproductive diseases. PMID:27546504

  14. Monitoring leptin activity using the chicken leptin receptor.

    Hen, Gideon; Yosefi, Sera; Ronin, Ana; Einat, Paz; Rosenblum, Charles I; Denver, Robert J; Friedman-Einat, Miriam

    2008-05-01

    We report on the construction of a leptin bioassay based on the activation of chicken leptin receptor in cultured cells. A human embryonic kidney (HEK)-293 cell line, stably transfected with the full-length cDNA of chicken leptin receptor together with a STAT3-responsive reporter gene specifically responded to recombinant human and Xenopus leptins. The observed higher sensitivity of chicken leptin receptor to the former is in agreement with the degree of sequence similarity among these species (about 60 and 38% identical amino acids between humans and chickens, and between humans and Xenopus respectively). The specific activation of signal transduction through the chicken leptin receptor, shown here for the first time, suggests that the transition of Gln269 (implicated in the Gln-to-Pro Zucker fatty mutation in rats) to Glu in chickens does not impair its activity. Analysis of leptin-like activity in human serum samples of obese and lean subjects coincided well with leptin levels determined by RIA. Serum samples of pre- and post partum cows showed a tight correlation with the degree of adiposity. However, specific activation of the chicken leptin receptor in this assay was not observed with serum samples from broiler or layer chickens (representing fat and lean phenotypes respectively) or with those from turkey. Similar leptin receptor activation profiles were observed with cells transfected with human leptin receptor. Further work is needed to determine whether the lack of leptin-like activity in the chicken serum samples is due to a lack of leptin in this species or simply to a serum level of leptin that is below the detection threshold. PMID:18434362

  15. Identification of COUP-TFII Orphan Nuclear Receptor as a Retinoic Acid-Activated Receptor

    Kruse, Schoen W; Suino-Powell, Kelly; Zhou, X Edward; Kretschman, Jennifer E; Reynolds, Ross; Vonrhein, Clemens; Xu, Yong; Wang, Liliang; Tsai, Sophia Y; Tsai, Ming-Jer; Xu, H Eric [Baylor; (Van Andel); (Globel Phasing); (Grand Valley)

    2010-01-12

    The chicken ovalbumin upstream promoter-transcription factors (COUP-TFI and II) make up the most conserved subfamily of nuclear receptors that play key roles in angiogenesis, neuronal development, organogenesis, cell fate determination, and metabolic homeostasis. Although the biological functions of COUP-TFs have been studied extensively, little is known of their structural features or aspects of ligand regulation. Here we report the ligand-free 1.48 {angstrom} crystal structure of the human COUP-TFII ligand-binding domain. The structure reveals an autorepressed conformation of the receptor, where helix {alpha}10 is bent into the ligand-binding pocket and the activation function-2 helix is folded into the cofactor binding site, thus preventing the recruitment of coactivators. In contrast, in multiple cell lines, COUP-TFII exhibits constitutive transcriptional activity, which can be further potentiated by nuclear receptor coactivators. Mutations designed to disrupt cofactor binding, dimerization, and ligand binding, substantially reduce the COUP-TFII transcriptional activity. Importantly, retinoid acids are able to promote COUP-TFII to recruit coactivators and activate a COUP-TF reporter construct. Although the concentration needed is higher than the physiological levels of retinoic acids, these findings demonstrate that COUP-TFII is a ligand-regulated nuclear receptor, in which ligands activate the receptor by releasing it from the autorepressed conformation.

  16. The pleiotropic effects of erythropoietin in the central nervous system.

    Buemi, M; Cavallaro, E; Floccari, F; Sturiale, A; Aloisi, C; Trimarchi, M; Corica, F; Frisina, N

    2003-03-01

    Erythropoietin (Epo) is a hydrophobic sialoglycoproteic hormone produced by the kidney and responsible for the proliferation, maturation, and differentiation of the precursors of the erythroid cell line. Human recombinant erythropoietin (rHuEpo) is used to treat different types of anemia, not only in uremic patients but also in newborns with anemia of prematurity, in patients with cancer-related anemia or myeloproliferative disease, thalassemias, bone marrow transplants, or those with chronic infectious diseases. The pleiotropic functions of Epo are well known. It has been shown that this hormone can modulate the inflammatory and immune response, has direct hemodynamic and vasoactive effects, could be considered a proangiogenic factor because of its interaction with vascular endothelial growth factor, and its ability to stimulate mitosis and motility of endothelial cells. The multifunctional role of Epo has further been confirmed by the discovery in the central nervous system of a specific Epo/Epo receptor (EpoR) system. Both Epo and EpoR are expressed by astrocytes and neurons and Epo is present in the cerebrospinal fluid (CSF). Therefore, novel functions of Epo, tissue-specific regulation, and the mechanisms of action have been investigated. In this review we have tried to summarize the current data on the role of Epo on brain function. We discuss the different sites of cerebral expression and mechanisms of regulation of Epo and its receptor and its role in the development and maturation of the brain. Second, we discuss the neurotrophic and neuroprotective function of Epo in different conditions of neuronal damage, such as hypoxia, cerebral ischemia, and subarachnoid hemorrhage, and the consequent possibility that rHuEpo therapy could soon be used in clinical practice to limit neuronal damage induced by these diseases. PMID:12638727

  17. Flavonoids with M1 Muscarinic Acetylcholine Receptor Binding Activity

    Meyyammai Swaminathan

    2014-06-01

    Full Text Available Muscarinic acetylcholine receptor-active compounds have potential for the treatment of Alzheimer’s disease. In this study, a series of natural and synthetic flavones and flavonols was assayed in vitro for their ability to inhibit radioligand binding at human cloned M1 muscarinic receptors. Several compounds were found to possess competitive binding affinity (Ki = 40–110 µM, comparable to that of acetylcholine (Ki = 59 µM. Despite the fact that these compounds lack a positively-charged ammonium group under physiological conditions, molecular modelling studies suggested that they bind to the orthosteric site of the receptor, mainly through non-polar interactions.

  18. Protective effects of erythropoietin pretreatment on myocardium with hypoxia/reoxygenation injury in rats

    QIN Chuan; XIAO Ying-bin; ZHONG Qan-jin; CHEN Lin; WANG Xue-feng

    2004-01-01

    To establish the rat model with myocardial hypoxia/reoxygenation (H/R) injury, and investigatethe protective effect of EPO pretreatment on the myocardium. Methods: Sixty male adult Wistar rats were randomly divided in-to 3 groups: control group, H/R group, and EPO group, 20 in each group. The rats in EPO group accepted injection of 5 000U/kg recombinant human erythropoietin (RHuEPO) through vein, and the other rats accepted the injection of the same volumeof saline. Twenty-four hours after the injection, rats in the EPO and H/R groups were put into the hypoxia environment for 12h and then returned to the normoxic environment for 2 h, and then the samples of blood and myocardium were collected. Serummyocardial enzyme activity, apoptosis, ultrastructure, myocardial MDA contents, EPO receptor (EPOR) expression in cardiacmyocytes and cardiac functions were tested. Results: EPOR expression was positive in cardiac myocytes of adult rat according to the result of immunohistochemitry assaying. Compared to those in H/R group, rats in EPO group presented lighter injury ofmyocardial ultrastructure, the reduction of serum myocardial enzyme activity, inhibition of apoptosis, the better recovery ofcardiac functions, and the Ness production of oxygen-derived free radicals. Conclusion: Adult rat cardiac myocytes could ex-press EPOR, and EPO pretreatment produced protective effects on myocardium with H/R injury.

  19. A mouse model of adult-onset anaemia due to erythropoietin deficiency.

    Yamazaki, Shun; Souma, Tomokazu; Hirano, Ikuo; Pan, Xiaoqing; Minegishi, Naoko; Suzuki, Norio; Yamamoto, Masayuki

    2013-01-01

    Erythropoietin regulates erythropoiesis in a hypoxia-inducible manner. Here we generate inherited super-anaemic mice (ISAM) as a mouse model of adult-onset anaemia caused by erythropoietin deficiency. ISAM express erythropoietin in the liver but lack erythropoietin production in the kidney. Around weaning age, when the major erythropoietin-producing organ switches from the liver to the kidney, ISAM develop anaemia due to erythropoietin deficiency, which is curable by administration of recombinant erythropoietin. In ISAM severe chronic anaemia enhances transgenic green fluorescent protein and Cre expression driven by the complete erythropoietin-gene regulatory regions, which facilitates efficient labelling of renal erythropoietin-producing cells. We show that the majority of cortical and outer medullary fibroblasts have the innate potential to produce erythropoietin, and also reveal a new set of erythropoietin target genes. ISAM are a useful tool for the evaluation of erythropoiesis-stimulating agents and to trace the dynamics of erythropoietin-producing cells. PMID:23727690

  20. Multiple autophosphorylation sites of the epidermal growth factor receptor are essential for receptor kinase activity and internalization. Contrasting significance of tyrosine 992 in the native and truncated receptors

    Sorkin, A; Helin, K; Waters, C M; Carpenter, G; Beguinot, L

    1992-01-01

    similar to a kinase-negative receptor. Mutation of tyrosine residue Y992 alone in the context of full length EGF receptor, however, did not affect receptor internalization or kinase activity toward phospholipase C-gamma 1. These data indicate that tyrosine 992 is critical for substrate phosphorylation and...... internalization only in the context of the truncated receptor, and that minor autophosphorylation sites, such as Y992, may act as compensatory regulatory sties in the absence of the major EGF receptor autophosphorylation sites....

  1. Peroxisome Proliferator-Activated Receptor and Vitamin D Receptor Signaling Pathways in Cancer Cells

    Peroxisome proliferator-activated receptors (PPARs) are members of the superfamily of nuclear hormone receptors, which respond to specific ligands such as polyunsaturated fatty acids by altering gene expression. Three subtypes of this receptor have been discovered, each evolving to achieve different biological functions. Like other nuclear receptors, the transcriptional activity of PPARs is affected not only by ligand-stimulation, but also by cross-talk with other molecules. For example, both PPARs and the RXRs are ligand-activated transcription factors that coordinately regulate gene expression. In addition, PPARs and vitamin D receptor (VDR) signaling pathways regulate a multitude of genes that are of importance for cellular functions including cell proliferation and cell differentiation. Interaction of the PPARs and VDR signaling pathways has been shown at the level of molecular cross-regulation of their transcription factor. A variety of ligands influencing the PPARs and VDR signaling pathways have been shown to reveal chemopreventive potential by mediating tumor suppressive activities in human cancers. Use of these compounds may represent a potential novel strategy to prevent cancers. This review summarizes the roles of the PPARs and the VDR in pathogenesis and progression of cancer

  2. Peroxisome Proliferator-Activated Receptor and Vitamin D Receptor Signaling Pathways in Cancer Cells

    Yasuko Kitagishi

    2013-10-01

    Full Text Available Peroxisome proliferator-activated receptors (PPARs are members of the superfamily of nuclear hormone receptors, which respond to specific ligands such as polyunsaturated fatty acids by altering gene expression. Three subtypes of this receptor have been discovered, each evolving to achieve different biological functions. Like other nuclear receptors, the transcriptional activity of PPARs is affected not only by ligand-stimulation, but also by cross-talk with other molecules. For example, both PPARs and the RXRs are ligand-activated transcription factors that coordinately regulate gene expression. In addition, PPARs and vitamin D receptor (VDR signaling pathways regulate a multitude of genes that are of importance for cellular functions including cell proliferation and cell differentiation. Interaction of the PPARs and VDR signaling pathways has been shown at the level of molecular cross-regulation of their transcription factor. A variety of ligands influencing the PPARs and VDR signaling pathways have been shown to reveal chemopreventive potential by mediating tumor suppressive activities in human cancers. Use of these compounds may represent a potential novel strategy to prevent cancers. This review summarizes the roles of the PPARs and the VDR in pathogenesis and progression of cancer.

  3. Peroxisome Proliferator-Activated Receptor and Vitamin D Receptor Signaling Pathways in Cancer Cells

    Matsuda, Satoru, E-mail: smatsuda@cc.nara-wu.ac.jp; Kitagishi, Yasuko [Department of Food Science and Nutrition, Nara Women’s University, Kita-Uoya Nishimachi, Nara 630-8506 (Japan)

    2013-10-21

    Peroxisome proliferator-activated receptors (PPARs) are members of the superfamily of nuclear hormone receptors, which respond to specific ligands such as polyunsaturated fatty acids by altering gene expression. Three subtypes of this receptor have been discovered, each evolving to achieve different biological functions. Like other nuclear receptors, the transcriptional activity of PPARs is affected not only by ligand-stimulation, but also by cross-talk with other molecules. For example, both PPARs and the RXRs are ligand-activated transcription factors that coordinately regulate gene expression. In addition, PPARs and vitamin D receptor (VDR) signaling pathways regulate a multitude of genes that are of importance for cellular functions including cell proliferation and cell differentiation. Interaction of the PPARs and VDR signaling pathways has been shown at the level of molecular cross-regulation of their transcription factor. A variety of ligands influencing the PPARs and VDR signaling pathways have been shown to reveal chemopreventive potential by mediating tumor suppressive activities in human cancers. Use of these compounds may represent a potential novel strategy to prevent cancers. This review summarizes the roles of the PPARs and the VDR in pathogenesis and progression of cancer.

  4. Enhanced brain release of erythropoietin, cytokines and NO during carotid clamping.

    Carelli, Stephana; Ghilardi, Giorgio; Bianciardi, Paola; Latorre, Elisa; Rubino, Federico; Bissi, Marina; Di Giulio, Anna Maria; Samaja, Michele; Gorio, Alfredo

    2016-02-01

    Although effective and safe, carotid endarterectomy (CEA) implies a reduced blood flow to the brain and likely an ischemia/reperfusion event. The high rate of uneventful outcomes associated with CEA suggests the activation of brain endogenous protection mechanisms aimed at limiting the possible ischemia/reperfusion damage. This study aims at assessing whether CEA triggers protective mechanisms such as brain release of erythropoietin and nitric oxide. CEA was performed in 12 patients; blood samples were withdrawn simultaneously from the surgically exposed ipsilateral jugular and leg veins before, during (2 and 40 min) and after clamp removal (2 min). Plasma antioxidant capacity, carbonylated proteins, erythropoietin, nitrates and nitrites (NOx) were determined. No changes in intraoperative EEG, peripheral and transcranial blood oxygen saturation were detectable, and no patients showed any neurologic sign after the intervention. Antioxidant capacity and protein carbonylation in plasma were unaffected. Differently, erythropoietin, VEGF, TNF-α and NOx increased during clamping in the jugular blood (2 and 40 min), while no changes were observed in the peripheral circulation. These results show that blood erythropoietin, VEGF, TNF-α, and NOx increased in the brain during uncomplicated CEA. This may represent an endogenous self-activated neuroprotective mechanism aimed at the prevention of ischemia/reperfusion damage. PMID:26494654

  5. Erythropoietin in heart failure : pathology and protection

    Westenbrink, Berend Daan

    2008-01-01

    Anemia is common in chronic heart failure (CHF) patients and related to impaired survival. The etiology of anemia in CHF-patients is often unknown. We hypothesized that dysregulation of erythropoietin (EPO) synthesis by the kidney or an altered sensitivity of the bone marrow to EPO might represent c

  6. High-dose erythropoietin for tissue protection

    Lund, Anton; Lundby, Carsten; Olsen, Niels Vidiendal

    2014-01-01

    BACKGROUND: The discovery of potential anti-apoptotic and cytoprotective effects of recombinant human erythropoietin (rHuEPO) has led to clinical trials investigating the use of high-dose, short-term rHuEPO therapy for tissue protection in conditions such as stroke and myocardial infarction...

  7. Erythropoietin: ready for prime-time cardioprotection.

    Riksen, N.P.; Hausenloy, D.J.; Yellon, D.M.

    2008-01-01

    To improve clinical outcomes in patients presenting with an acute myocardial infarction, new strategies to limit infarct size and postinfarct remodelling are warranted. Recent animal studies have revealed that erythropoietin has the potential to achieve both these goals. Even more intriguing is the

  8. Neurotrophin receptors expression and JNK pathway activation in human astrocytomas

    Neurotrophins are growth factors that regulate cell growth, differentiation and apoptosis in the nervous system. Their diverse actions are mediated through two different transmembrane – receptor signaling systems: Trk receptor tyrosine kinases (TrkA, TrkB, TrkC) and p75NTR neurotrophin receptor. Trk receptors promote cell survival and differentiation while p75NTR induces, in most cases, the activity of JNK-p53-Bax apoptosis pathway or suppresses intracellular survival signaling cascades. Robust Trk activation blocks p75NTR -induced apoptosis by suppressing the JNK-p53-Bax pathway. The aim of this exploratory study was to investigate the expression levels of neurotrophin receptors, Trks and p75NTR, and the activation of JNK pathway in human astrocytomas and in adjacent non-neoplastic brain tissue. Formalin-fixed paraffin-embedded serial sections from 33 supratentorial astrocytomas (5 diffuse fibrillary astrocytomas, WHO grade II; 6 anaplastic astrocytomas, WHO grade III; 22 glioblastomas multiforme, WHO grade IV) were immunostained following microwave pretreatment. Polyclonal antibodies against TrkA, TrkB, TrkC and monoclonal antibodies against p75NTR and phosphorylated forms of JNK (pJNK) and c-Jun (pc-Jun) were used. The labeling index (LI), defined as the percentage of positive (labeled) cells out of the total number of tumor cells counted, was determined. Moderate to strong, granular cytoplasmic immunoreactivity for TrkA, TrkB and TrkC receptors was detected in greater than or equal to 10% of tumor cells in the majority of tumors independently of grade; on the contrary, p75NTR receptor expression was found in a small percentage of tumor cells (~1%) in some tumors. The endothelium of tumor capillaries showed conspicuous immunoreactivity for TrkB receptor. Trk immunoreactivity seemed to be localized in some neurons and astrocytes in non-neoplastic tissue. Phosphorylated forms of JNK (pJNK) and c-Jun (pc-Jun) were significantly co-expressed in a tumor grade

  9. Development of a new radioimmunoassay for erythropoietin using recombinant erythropoietin

    Mason-Garcia, M.; Beckman, B.S.; Brookins, J.W.; Powell, J.S.; Lanham, W.; Blaisdell, S.; Keay, L.; Li, S.C.; Fisher, J.W. (Tulane Univ. School of Medicine, New Orleans, LA (USA))

    1990-11-01

    The development of a 24 hour radioimmunoassay for erythropoietin (EPO) using EPO derived from recombinant DNA as both immunogen and ligand is described in the present paper. Mixed breed rabbits immunized with 10 micrograms/kg of EPO derived from a stably transfected cell line (MD) produced antibodies to EPO with high titer (up to 1:896,000 final dilution in the tube), high affinity (8.4 x 10(11) liter/M), and good specificity. Purified EPO from the above source or from AmGen Biologicals (AG) were successfully radioiodinated with the chloramine-T method and used as ligand in the radioimmunoassay. Standard dose-response curves prepared with EPO from both commercial sources were not significantly different and showed a sensitivity of 0.75 to 0.96 mU/tube. The dose-response curves in both systems also showed parallelism with serially diluted serum from a patient with aplastic anemia. Within-assay and between-assay precision were determined by assaying multiple replicates of a serum pool. Recovery of exogenous EPO added to a serum pool averaged 97% for both systems. The range of normal human serum EPO was determined by assaying the sera of 153 hematologically-normal adult subjects and was found to be 1.1 to 27.3 mU/ml for MD EPO and 0.5 to 16.7 mU/ml for AG EPO. Sera from several patients with hematologic abnormalities were also assayed, including those of 36 patients with anemia of end-stage renal disease (mean +/- SEM, 29.5 +/- 4.0 mU/ml; P less than 0.01). In conclusion, this new, more rapid and sensitive radioimmunoassay system can be used to measure EPO levels in sera from normal human subjects and patients with several types of anemia, and should also be very useful in therapeutic drug monitoring of patients receiving EPO from various commercial sources.

  10. Structural mechanism of glutamate receptor activation and desensitization.

    Meyerson, Joel R; Kumar, Janesh; Chittori, Sagar; Rao, Prashant; Pierson, Jason; Bartesaghi, Alberto; Mayer, Mark L; Subramaniam, Sriram

    2014-10-16

    Ionotropic glutamate receptors are ligand-gated ion channels that mediate excitatory synaptic transmission in the vertebrate brain. To gain a better understanding of how structural changes gate ion flux across the membrane, we trapped rat AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) and kainate receptor subtypes in their major functional states and analysed the resulting structures using cryo-electron microscopy. We show that transition to the active state involves a 'corkscrew' motion of the receptor assembly, driven by closure of the ligand-binding domain. Desensitization is accompanied by disruption of the amino-terminal domain tetramer in AMPA, but not kainate, receptors with a two-fold to four-fold symmetry transition in the ligand-binding domains in both subtypes. The 7.6 Å structure of a desensitized kainate receptor shows how these changes accommodate channel closing. These findings integrate previous physiological, biochemical and structural analyses of glutamate receptors and provide a molecular explanation for key steps in receptor gating. PMID:25119039

  11. Abelson tyrosine kinase links PDGFbeta receptor activation to cytoskeletal regulation of NMDA receptors in CA1 hippocampal neurons

    Beazely Michael A

    2008-12-01

    Full Text Available Abstract Background We have previously demonstrated that PDGF receptor activation indirectly inhibits N-methyl-D-aspartate (NMDA currents by modifying the cytoskeleton. PDGF receptor ligand is also neuroprotective in hippocampal slices and cultured neurons. PDGF receptors are tyrosine kinases that control a variety of signal transduction pathways including those mediated by PLCγ. In fibroblasts Src and another non-receptor tyrosine kinase, Abelson kinase (Abl, control PDGF receptor regulation of cytoskeletal dynamics. The mechanism whereby PDGF receptor regulates cytoskeletal dynamics in central neurons remains poorly understood. Results Intracellular applications of active Abl, but not heat-inactivated Abl, decreased NMDA-evoked currents in isolated hippocampal neurons. This mimics the effects of PDGF receptor activation in these neurons. The Abl kinase inhibitor, STI571, blocked the inhibition of NMDA currents by Abl. We demonstrate that PDGF receptors can activate Abl kinase in hippocampal neurons via mechanisms similar to those observed previously in fibroblasts. Furthermore, PDGFβ receptor activation alters the subcellular localization of Abl. Abl kinase is linked to actin cytoskeletal dynamics in many systems. We show that the inhibition of NMDA receptor currents by Abl kinase is blocked by the inclusion of the Rho kinase inhibitor, Y-27632, and that activation of Abl correlates with an increase in ROCK tyrosine phosphorylation. Conclusion This study demonstrates that PDGFβ receptors act via an interaction with Abl kinase and Rho kinase to regulated cytoskeletal regulation of NMDA receptor channels in CA1 pyramidal neurons.

  12. Comparison of in vivo biological activity of recombinant human erythropoietin in two species of mice%重组人促红素在2种品系小鼠体内的生物学活性的比较

    张素慧; 王巧旭; 徐超瑾; 程小芹; 唐黎明

    2013-01-01

    目的:对中国药典2010年版三部附录XB重组人促红素(rHuEPO)体内生物学活性测定方法中规定的动物品系进行探讨研究.方法:选用ICR小鼠、BALB/C小鼠作为实验动物,测定19批进口重组人促红素的体内生物学活性,从动物品系、性别的角度进行比较.结果:19批重组人促红素在雌性或雄性ICR小鼠、BALB/C小鼠体内生物学活性之间的差异无统计学意义;每组ICR小鼠的性别为雌雄各半时,体内生物学活性合标示量符合药典规定,但可信限率(FL)超过45%,结果不可靠.结论:ICR小鼠与BALB/C小鼠均可用于重组人促红素体内生物学活性测定,采用单一性别的动物进行试验结果更为可靠.%Objective:To explore animal species used in bioassay of recombinant human erythropoietin (rHuEPO) in Appendix XB of Chinese Pharmacopoeia Volume Ⅲ (2010 Edition).Methods:ICR mice and BALB/C mice were selected as the experiment animal,and in vivo biological activities of nineteen batches of rHuEPO were determined and compared in terms of animal species and sex.Results:The results indicated that in vivo biological activities of 19 batches of rHuEPO in BALB/C mice were similar to those in ICR mice of either sex.In groups of ICR mice of half males and half females,the in vivo biological activity was in accordance with the label claim standardized in the Chinese Pharmacopoeia ; however,the confidence limit rate was high (FL > 45 %),indicating that the result was unreliable.Conclusion:Both ICR mice and BALB/C mice can be applied for in vivo bioassay of rHuEPO.Results will be more reliable if data are from the group of single sex mice.

  13. Epidermis-type lipoxygenase 3 regulates adipocyte differentiation and peroxisome proliferator-activated receptor gamma activity

    Hallenborg, Philip; Jørgensen, Claus; Petersen, Rasmus K;

    2010-01-01

    The nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR gamma) is essential for adipogenesis. Although several fatty acids and their derivatives are known to bind and activate PPAR gamma, the nature of the endogenous ligand(s) promoting the early stages of adipocyte differenti...

  14. Binding of erythropoietin to CFU-E derived from fetal mouse liver cells

    Fukamachi, H.; Saito, T.; Tojo, A.; Kitamura, T.; Urabe, A.; Takaku, F.

    1987-09-01

    The binding of recombinant erythropoietin (EPO) to fetal mouse liver cells (FMLC) was investigated using a radioiodinated derivative which retained full biological activity. FMLC were fractionated using a preformed Percoll density gradient. Using the fractionated FMLC, the ability to form CFU-E colonies in a semisolid culture was examined, and the binding of (/sup 125/I)EPO was measured. The highest specific binding of (/sup 125/I)EPO was observed in a fraction with a density between 1.062 and 1.076 g/ml. The same fraction showed the highest ability to form CFU-E-derived colonies. After suspension culture of FMLC with EPO for 2 days, differentiated erythroid cells with higher density markedly increased. The specific binding of (/sup 125/I)EPO to these cells almost disappeared with differentiation. Scatchard analysis with cells of the CFU-E-enriched fraction showed a nonlinear curve, suggesting the existence of two classes of binding sites. One binding site was high-affinity (Kd1 = 0.41 nM), and the other low-affinity (Kd2 = 3.13 nM). These results suggest that the expression of EPO receptors on the erythroid cells is highest in CFU-E.

  15. A lentiviral gene therapy strategy for the in vitro production of feline erythropoietin.

    Natalia Vapniarsky

    Full Text Available Nonregenerative anemia due to chronic renal failure is a common problem in domestic cats. Unfortunately, administration of recombinant human erythropoietin often only improves anemia temporarily due to antibody development. In this in vitro study, feline erythropoietin cDNA was cloned from feline renal tissue and utilized in the construction of a replication-defective lentiviral vector. The native recombinant feline erythropoietin (rfEPO sequence was confirmed by sequencing. Upon viral vector infection of human 293H cells, Crandall Renal Feline Kidney cell line and primary feline peripheral blood mononuclear cells, bioactive rfEPO protein was produced. The presence of cellular rfEPO cDNA was confirmed by standard PCR, production of abundant rfEPO mRNA was confirmed by real-time PCR, and secretion of rfEPO protein was demonstrated by Western blot analyses, while rfEPO protein bioactivity was confirmed via an MTT proliferation bioassay. This in vitro study demonstrates the feasibility of a replication-defective lentiviral vector delivery system for the in vitro production of biologically active feline erythropoietin. Anemic cats with chronic renal failure represent a potential in vivo application of a lentiviral gene therapy system.

  16. Tyrosines 868, 966, and 972 in the Kinase Domain of JAK2 Are Autophosphorylated and Required for Maximal JAK2 Kinase Activity

    Argetsinger, Lawrence S.; Stuckey, Jeanne A.; Robertson, Scott A.; Koleva, Rositsa I.; Cline, Joel M.; Marto, Jarrod A.; Myers, Martin G.; Carter-Su, Christin

    2010-01-01

    Janus kinase 2 (JAK2) is activated by a majority of cytokine family receptors including receptors for GH, leptin, and erythropoietin. To identify novel JAK2-regulatory and/or -binding sites, we set out to identify autophosphorylation sites in the kinase domain of JAK2. Two-dimensional phosphopeptide mapping of in vitro autophosphorylated JAK2 identified tyrosines 868, 966, and 972 as sites of autophosphorylation. Phosphorylated tyrosines 868 and 972 were also identified by mass spectrometry a...

  17. New GABA amides activating GABA A-receptors

    Peter Raster; Andreas Späth; Svetlana Bultakova; Pau Gorostiza; Burkhard König; Piotr Bregestovski

    2013-01-01

    We have prepared a series of new and some literature-reported GABA-amides and determined their effect on the activation of GABAA-receptors expressed in CHO cells. Special attention was paid to the purification of the target compounds to remove even traces of GABA contaminations, which may arise from deprotection steps in the synthesis. GABA-amides were previously reported to be partial, full or superagonists. In our hands these compounds were not able to activate GABAA-receptor channels in wh...

  18. Polycythemia in transgenic mice expressing the human erythropoietin gene

    Erythropoietin is a glycoprotein hormone that regulates mammalian erythropoiesis. To study the expression of the human erythropoietin gene, EPO, 4 kilobases of DNA encompassing the gene with 0.4 kilobase of 5' flanking sequence and 0.7 kilobase of 3' flanking sequence was microinjected into fertilized mouse eggs. Transgenic mice were generated that are polycythemic, with increased erythrocytic indices in peripheral blood, increased numbers of erythroid precursors in hematopoietic tissue, and increased serum erythropoietin levels. Transgenic homozygotes show a greater degree of polycythemia than do heterozygotes as well as striking extramedullary erythropoiesis. Human erythropoietin RNA was found not only in fetal liver, adult liver, and kidney but also in all other transgenic tissues analyzed. Anemia induced increased human erythropoietin RNA levels in liver but not kidney. These transgenic mice represent a unique model of polycythemia due to increased erythropoietin levels

  19. Beyond anaemia management: evolving role of erythropoietin therapy in neurological disorders, multiple myeloma and tumour hypoxia models.

    Boogaerts, Marc; Mittelman, Moshe; Vaupel, Peter

    2005-01-01

    Recombinant human erythropoietin (epoetin) has become the standard of care in the treatment of anaemia resulting from cancer and its treatment, and chronic kidney disease. The discovery that erythropoietin and its receptor are located in regions outside the erythropoietic system has led to interest in the potential role of epoetin in other tissues, such as the central nervous system. Animal studies have shown that systemically applied epoetin can cross the blood-brain barrier, where it reduces tissue injury associated with stroke, blunt trauma and experimental autoimmune encephalomyelitis. Pilot studies in humans have shown that epoetin treatment given within 8 h of stroke reduces infarct size and results in a significantly better outcome when compared with placebo treatment. Studies also suggest that epoetin has the potential to improve cognitive impairment associated with adjuvant chemotherapy in patients with cancer. Anaemia is a major factor causing tumour hypoxia, a condition that can promote changes within neoplastic cells that further tumour survival and malignant progression and also reduces the effectiveness of several anticancer therapies including radiotherapy and oxygen-dependent cytotoxic agents. Use of epoetin to prevent or correct anaemia has the potential to reduce tumour hypoxia and improve treatment outcome. Several therapeutic studies in anaemic animals with experimental tumours have shown a beneficial effect of epoetin on delaying tumour growth. Furthermore, clinical observations in patients with multiple myeloma and animal studies have suggested that epoetin has an antimyeloma effect, mediated via the immune system through activation of CD8+ T cells. Therefore, the role of epoetin may go well beyond that of increasing haemoglobin levels in anaemic patients, although additional studies are required to confirm these promising results. PMID:16244507

  20. Mechanisms of Activation of Receptor Tyrosine Kinases: Monomers or Dimers

    Ichiro N. Maruyama

    2014-04-01

    Full Text Available Receptor tyrosine kinases (RTKs play essential roles in cellular processes, including metabolism, cell-cycle control, survival, proliferation, motility and differentiation. RTKs are all synthesized as single-pass transmembrane proteins and bind polypeptide ligands, mainly growth factors. It has long been thought that all RTKs, except for the insulin receptor (IR family, are activated by ligand-induced dimerization of the receptors. An increasing number of diverse studies, however, indicate that RTKs, previously thought to exist as monomers, are present as pre-formed, yet inactive, dimers prior to ligand binding. The non-covalently associated dimeric structures are reminiscent of those of the IR family, which has a disulfide-linked dimeric structure. Furthermore, recent progress in structural studies has provided insight into the underpinnings of conformational changes during the activation of RTKs. In this review, I discuss two mutually exclusive models for the mechanisms of activation of the epidermal growth factor receptor, the neurotrophin receptor and IR families, based on these new insights.

  1. Calcium-sensing receptor activation depresses synaptic transmission

    Phillips, Cecilia G.; Harnett, Mark T.; Chen, Wenyan; Smith, Stephen M.

    2008-01-01

    At excitatory synapses, decreases in cleft [Ca] arising from activity-dependent transmembrane Ca flux reduce the probability of subsequent transmitter release. Intense neural activity, induced by physiological and pathological stimuli, disturb the external microenvironment reducing extracellular [Ca] ([Ca]o) and thus may impair neurotransmission. Increases in [Ca]o activate the extracellular calcium sensing receptor (CaSR) which in turn inhibits non-selective cation channels (NSCC) at the maj...

  2. Allosteric activation mechanism of the cys-loop receptors

    Yong-chang CHANG; Wen WU; Jian-liang ZHANG; Yao HUANG

    2009-01-01

    Binding of a neurotransmitter to its ionotropic receptor opens a distantly located ion channel, a process termed allosteric activation. Here we review recent advances in the molecular mechanism by which the cys-loop receptors are activated with emphasis on the best studied nicotinic acetylcholine receptors (nAChRs). With a combination of affinity labeling, mutagenesis, electrophysiology, kinetic modeling, electron microscopy (EM), and crystal structure analysis, the allosteric activation mechanism is emerging. Specifically, the binding domain and gating domain are interconnected by an allosteric activation network. Agonist binding induces conformational changes, resulting in the rotation of a β sheet of amino-terminal domain and outward movement of loop 2, loop F, and cys-loop, which are coupled to the M2-M3 linker to pull the channel to open. However, there are still some controversies about the movement of the channel-lining domain M2. Nine angstrom resolution EM structure of a nAChR imaged in the open state suggests that channel opening is the result of rotation of the M2 domain. In contrast, recent crystal structures of bacterial homologues of the cys-loop receptor family in apparently open state have implied an M2 tilting model with pore dilation and quaternary twist of the whole pentameric receptor. An elegant study of the nAChR using protonation scanning of M2 domain supports a similar pore dilation activation mechanism with minimal rotation of M2. This remains to be validated with other approaches including high resolution structure determination of the mammalian cys-loop receptors in the open state.

  3. Kallikrein activates bradykinin B2 receptors in absence of kininogen.

    Biyashev, Dauren; Tan, Fulong; Chen, Zhenlong; Zhang, Kai; Deddish, Peter A; Erdös, Ervin G; Hecquet, Claudie

    2006-03-01

    Kallikreins cleave plasma kininogens to release the bioactive peptides bradykinin (BK) or kallidin (Lys-BK). These peptides then activate widely disseminated B2 receptors with consequences that may be either noxious or beneficial. We used cultured cells to show that kallikrein can bypass kinin release to activate BK B2 receptors directly. To exclude intermediate kinin release or kininogen uptake from the cultured medium, we cultured and maintained cells in medium entirely free of animal proteins. We compared the responses of stably transfected Chinese hamster ovary (CHO) cells that express human B2 receptors (CHO B2) and cells that coexpress angiotensin I-converting enzyme (ACE) as well (CHO AB). We found that BK (1 nM or more) and tissue kallikrein (1-10 nM) both significantly increased release of arachidonic acid beyond unstimulated baseline level. An enzyme-linked immunoassay for kinin established that kallikrein did not release a kinin from CHO cells. We confirmed the absence of kininogen mRNA with RT-PCR to rule out kininogen synthesis by CHO cells. We next tested an ACE inhibitor for enhanced BK receptor activation in the absence of kinin release and synthesized an ACE-resistant BK analog as a control for these experiments. Enalaprilat (1 microM) potentiated kallikrein (100 nM) in CHO AB cells but was ineffective in CHO B2 cells that do not bear ACE. We concluded that kallikrein activated B2 receptors without releasing a kinin. Furthermore, inhibition of ACE enhanced the receptor activation by kallikrein, an action that may contribute to the manifold therapeutic effects of ACE inhibitors. PMID:16272198

  4. Antierythropoietin Antibodies in Hemodialysis Patients Treated with Recombinant Erythropoietin

    Savaş ÖZTÜRK; Alper GÜMÜŞ; Vecihi MEMİLİ; Muhammet Emin DÜZ; Egemen CEBECİ; Macit KOLDAŞ; Rümeyza KAZANCIOĞLU

    2014-01-01

    OBJECTIVE: Erythropoietin resistance is a serious problem in patients treated with recombinant erythropoietin. Antierythropoietin antibodies are considered to be one of the causes of this resistance. MATERIAL and ME THODS: We investigated antierythropoietin antibodies in chronic hemodialysis patients and compared the results with healthy controls by means of establishing an ELISA method. A total of 121 chronic hemodialysis patients receiving recombinant erythropoietin were included in the ...

  5. Effects of Recombinant Erythropoietin on Breast Cancer-Initiating Cells

    Tiffany M. Phillips; Kwanghee Kim; Erina Vlashi; McBride, William H.; Frank Pajonk

    2007-01-01

    BACKGROUND: Cancer anemia causes fatigue and correlates with poor treatment outcome. Erythropoietin has been introduced in an attempt to correct these defects. However, five recent clinical trials reported a negative impact of erythropoietin on survival and/or tumor control, indicating that experimental evaluation of a possible direct effect of erythropoietin on cancer cells is required. Cancer recurrence is thought to rely on the proliferation of cancer initiating cells (CICs). In breast can...

  6. Antierythropoietin Antibodies in Hemodialysis Patients Treated with Recombinant Erythropoietin

    Savaş ÖZTÜRK

    2014-05-01

    Full Text Available OBJECTIVE: Erythropoietin resistance is a serious problem in patients treated with recombinant erythropoietin. Antierythropoietin antibodies are considered to be one of the causes of this resistance. MATERIAL and ME THODS: We investigated antierythropoietin antibodies in chronic hemodialysis patients and compared the results with healthy controls by means of establishing an ELISA method. A total of 121 chronic hemodialysis patients receiving recombinant erythropoietin were included in the study. The patients were subdivided according to the type of recombinant erythropoietin (erythropoietin-α or erythropoietin-β they had been treated with in the last six months. RESULTS: The absorbance values of patients were compared with the absorbance values of the control group by a specific and reproducible method. LOD (limit of detection and LOQ (limit of quantitation values were also calculated. The difference in the absorbance values between the therapy and control groups was statistically significant. CONCLUSION: Both erythropoietin-α and erythropoietin-β induce production of antibodies against erythropoietin. Anti rh-EPO antibodies may play a role in EPO resistance.

  7. Interaction of the C-terminal acidic domain of the insulin receptor with histone modulates the receptor kinase activity.

    Baron, V; Kaliman, P; Alengrin, F; Van Obberghen, E

    1995-04-01

    In this study, we investigated the role of the insulin receptor domain 1270-1280, an acid-rich sequence located in the receptor C-terminus. Antipeptide IgG raised against this sequence were obtained and used to analyze their effect on receptor function. Antipeptide IgG inhibited receptor autophosphorylation at Tyr1146, Tyr1150 and Tyr1151. These sites are known to be key modulators of the receptor activity. Autophosphorylation at other sites may also have been inhibited. The antipeptide antibody decreased the receptor kinase activity measured with poly(Glu80Tyr20) and a synthetic peptide corresponding to the proreceptor sequence 1142-1158. We provide evidence that the effect of the antibody on substrate phosphorylation may result from the control of the phosphorylation level of the receptor. Concerning the action of the antipeptide IgG on the receptor kinase activity, histone did not behave similarly to poly(Glu80Tyr20). The antibody recognizing sequence 1270-1280 competed with histone for an overlapping binding site. Histone also modulated insulin receptor autophosphorylation, supporting the idea that interference with domain 1270-1280 alters the receptor kinase. Our data suggest that the acidic region including residues 1270-1280 of the insulin receptor C-terminus is involved in the following events: (a) receptor binding with histone, an exogenous substrate of the receptor kinase, and (b) the regulation of receptor autophosphorylation and kinase activity. Based on these observations, we would like to propose that this insulin receptor domain could interact with cellular proteins modulating the receptor kinase. PMID:7744039

  8. Sphingosine-1-phosphate receptor 1 reporter mice reveal receptor activation sites in vivo

    Kono, Mari; Tucker, Ana E.; Tran, Jennifer; Bergner, Jennifer B.; Turner, Ewa M; Proia, Richard L.

    2014-01-01

    Activation of the GPCR sphingosine-1-phosphate receptor 1 (S1P1) by sphingosine-1-phosphate (S1P) regulates key physiological processes. S1P1 activation also has been implicated in pathologic processes, including autoimmunity and inflammation; however, the in vivo sites of S1P1 activation under normal and disease conditions are unclear. Here, we describe the development of a mouse model that allows in vivo evaluation of S1P1 activation. These mice, known as S1P1 GFP signaling mice, produce a ...

  9. Systemic and cerebral vascular endothelial growth factor levels increase in murine cerebral malaria along with increased Calpain and caspase activity and can be reduced by erythropoietin treatment

    Hempel, Casper; Hoyer, Nils; Kildemoes, Anna;

    2014-01-01

    . Furthermore, we noticed increased caspase-3 and calpain activity in terminally ill mice, as measured by protease-specific cleavage of α-spectrin and p35. In conclusion, we detected increased cerebral and systemic VEGF as well as HIF-1α, which in the brain were reduced to normal in EPO-treated mice. Also...

  10. The aryl hydrocarbon receptor and glucocorticoid receptor interact to activate human metallothionein 2A

    Sato, Shoko, E-mail: satosho@rs.tus.ac.jp [Laboratory of Nutrition, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555 (Japan); Shirakawa, Hitoshi, E-mail: shirakah@m.tohoku.ac.jp [Laboratory of Nutrition, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555 (Japan); Tomita, Shuhei, E-mail: tomita@med.tottori-u.ac.jp [Division of Molecular Pharmacology, Department of Pathophysiological and Therapeutic Science, Yonago 683-8503 (Japan); Tohkin, Masahiro, E-mail: tohkin@phar.nagoya-cu.ac.jp [Department of Medical Safety Science, Graduate School of Pharmaceutical Science, Nagoya City University, Nagoya 267-8603 (Japan); Gonzalez, Frank J., E-mail: gonzalef@mail.nih.gov [Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 (United States); Komai, Michio, E-mail: mkomai@m.tohoku.ac.jp [Laboratory of Nutrition, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555 (Japan)

    2013-11-15

    Although the aryl hydrocarbon receptor (AHR) and glucocorticoid receptor (GR) play essential roles in mammalian development, stress responses, and other physiological events, crosstalk between these receptors has been the subject of much debate. Metallothioneins are classic glucocorticoid-inducible genes that were reported to increase upon treatment with AHR agonists in rodent tissues and cultured human cells. In this study, the mechanism of human metallothionein 2A (MT2A) gene transcription activation by AHR was investigated. Cotreatment with 3-methylcholanthrene and dexamethasone, agonists of AHR and GR respectively, synergistically increased MT2A mRNA levels in HepG2 cells. MT2A induction was suppressed by RNA interference against AHR or GR. Coimmunoprecipitation experiments revealed a physical interaction between AHR and GR proteins. Moreover, chromatin immunoprecipitation assays indicated that AHR was recruited to the glucocorticoid response element in the MT2A promoter. Thus, we provide a novel mechanism whereby AHR modulates expression of human MT2A via the glucocorticoid response element and protein–protein interactions with GR. - Highlights: • Aryl hydrocarbon receptor forms a complex with glucocorticoid receptor in cells. • Human metallothionein gene is regulated by the AHR and GR interaction. • AHR–GR complex binds to glucocorticoid response element in metallothionein gene. • We demonstrated a novel transcriptional mechanism via AHR and GR interaction.