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Yu L, Ji W, Zhang H, Renda MJ, He Y, Lin S, Cheng EC, Chen H, Krause DS, Min W. SENP1-mediated GATA1 deSUMOylation is critical for definitive erythropoiesis. J Exp Med 2010; 207:1183-95. [PMID: 20457756 PMCID: PMC2882842 DOI: 10.1084/jem.20092215] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Accepted: 04/15/2010] [Indexed: 12/28/2022] Open
Abstract
Small ubiquitin-like modifier (SUMO) modification of proteins (SUMOylation) and deSUMOylation have emerged as important regulatory mechanisms for protein function. SENP1 (SUMO-specific protease) deconjugates SUMOs from modified proteins. We have created SENP1 knockout (KO) mice based on a Cre-loxP system. Global deletion of SENP1 (SENP1 KO) causes anemia and embryonic lethality between embryonic day 13.5 and postnatal day 1, correlating with erythropoiesis defects in the fetal liver. Bone marrow transplantation of SENP1 KO fetal liver cells to irradiated adult recipients confers erythropoiesis defects. Protein analyses show that the GATA1 and GATA1-dependent genes are down-regulated in fetal liver of SENP1 KO mice. This down-regulation correlates with accumulation of a SUMOylated form of GATA1. We further show that SENP1 can directly deSUMOylate GATA1, regulating GATA1-dependent gene expression and erythropoiesis by in vitro assays. Moreover, we demonstrate that GATA1 SUMOylation alters its DNA binding, reducing its recruitment to the GATA1-responsive gene promoter. Collectively, we conclude that SENP1 promotes GATA1 activation and subsequent erythropoiesis by deSUMOylating GATA1.
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Affiliation(s)
- Luyang Yu
- Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Stem Cell Center, and Department of Laboratory Medicine and Pathology, Yale University School of Medicine, New Haven, CT 06520
| | - Weidong Ji
- Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Stem Cell Center, and Department of Laboratory Medicine and Pathology, Yale University School of Medicine, New Haven, CT 06520
| | - Haifeng Zhang
- Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Stem Cell Center, and Department of Laboratory Medicine and Pathology, Yale University School of Medicine, New Haven, CT 06520
| | - Matthew J. Renda
- Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Stem Cell Center, and Department of Laboratory Medicine and Pathology, Yale University School of Medicine, New Haven, CT 06520
| | - Yun He
- Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Stem Cell Center, and Department of Laboratory Medicine and Pathology, Yale University School of Medicine, New Haven, CT 06520
| | - Sharon Lin
- Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Stem Cell Center, and Department of Laboratory Medicine and Pathology, Yale University School of Medicine, New Haven, CT 06520
| | - Ee-chun Cheng
- Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Stem Cell Center, and Department of Laboratory Medicine and Pathology, Yale University School of Medicine, New Haven, CT 06520
| | - Hong Chen
- Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Stem Cell Center, and Department of Laboratory Medicine and Pathology, Yale University School of Medicine, New Haven, CT 06520
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Diane S. Krause
- Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Stem Cell Center, and Department of Laboratory Medicine and Pathology, Yale University School of Medicine, New Haven, CT 06520
| | - Wang Min
- Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Stem Cell Center, and Department of Laboratory Medicine and Pathology, Yale University School of Medicine, New Haven, CT 06520
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102
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Insertion of an NPVY sequence into the cytosolic domain of the erythropoietin receptor selectively affects erythropoietin-mediated signalling and function. Biochem J 2010; 427:305-12. [DOI: 10.1042/bj20091951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
EPO (erythropoietin), the major hormone regulating erythropoiesis, functions via activation of its cell-surface receptor (EPO-R) present on erythroid progenitor cells. One of the most striking properties of EPO-R is its low expression on the cell surface, as opposed to its high intracellular levels. The low cell-surface expression of EPO-R may thus limit the efficacy of EPO that is routinely used to treat primary and secondary anaemia. In a recent study [Nahari, Barzilay, Hirschberg and Neumann (2008) Biochem. J. 410, 409–416] we have shown that insertion of an NPVY sequence into the intracellular domain of EPO-R increases its cell-surface expression. In the present study we demonstrate that this NPVY EPO-R insert has a selective effect on EPO-mediated downstream signalling in Ba/F3 cells expressing this receptor (NPVY-EPO-R). This is monitored by increased phosphorylation of the NPVY-EPO-R (on Tyr479), Akt, JAK2 (Janus kinase 2) and ERK1/2 (extracellular-signal-regulated kinase 1/2), but not STAT5 (signal transducer and activator of transcription 5), as compared with cells expressing wild-type EPO-R. This enhanced signalling is reflected in augmented proliferation at low EPO levels (0.05 units/ml) and protection against etoposide-induced apoptosis. Increased cell-surface levels of NPVY-EPO-R are most probably not sufficient to mediate these effects as the A234E-EPO-R mutant that is expressed at high cell-surface levels does not confer an augmented response to EPO. Taken together, we demonstrate that insertion of an NPVY sequence into the cytosolic domain of the EPO-R confers not only improved maturation, but also selectively affects EPO-mediated signalling resulting in an improved responsiveness to EPO reflected in cell proliferation and protection against apoptosis.
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103
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Pro-inflammatory cytokine-mediated anemia: regarding molecular mechanisms of erythropoiesis. Mediators Inflamm 2010; 2009:405016. [PMID: 20204172 PMCID: PMC2830572 DOI: 10.1155/2009/405016] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2009] [Accepted: 12/17/2009] [Indexed: 12/26/2022] Open
Abstract
Anemia of cancer and chronic inflammatory diseases is a frequent complication affecting quality of life. For cancer patients it represents a particularly bad prognostic. Low level of erythropoietin is considered as one of the causes of anemia in these pathologies. The deficiency in erythropoietin production results from pro-inflammatory cytokines effect. However, few data is available concerning molecular mechanisms involved in cytokine-mediated anemia. Some recent publications have demonstrated the direct effect of pro-inflammatory cytokines on cell differentiation towards erythroid pathway, without erythropoietin defect. This suggested that pro-inflammatory cytokine-mediated signaling pathways affect erythropoietin activity. They could interfere with erythropoietin-mediated signaling pathways, inducing early apoptosis and perturbing the expression and regulation of specific transcription factors involved in the control of erythroid differentiation. In this review we summarize the effect of tumor necrosis factor (TNF)α, TNF-related apoptosis-inducing ligand (TRAIL), and interferon (IFN)-γ on erythropoiesis with a particular interest for molecular feature.
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104
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Lee HY, Johnson KD, Fujiwara T, Boyer ME, Kim SI, Bresnick EH. Controlling hematopoiesis through sumoylation-dependent regulation of a GATA factor. Mol Cell 2010; 36:984-95. [PMID: 20064464 DOI: 10.1016/j.molcel.2009.11.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Revised: 06/20/2009] [Accepted: 09/25/2009] [Indexed: 12/26/2022]
Abstract
GATA factors establish transcriptional networks that control fundamental developmental processes. Whereas the regulator of hematopoiesis GATA-1 is subject to multiple posttranslational modifications, how these modifications influence GATA-1 function at endogenous loci is unknown. We demonstrate that sumoylation of GATA-1 K137 promotes transcriptional activation only at target genes requiring the coregulator Friend of GATA-1 (FOG-1). A mutation of GATA-1 V205G that disrupts FOG-1 binding and K137 mutations yielded similar phenotypes, although sumoylation was FOG-1 independent, and FOG-1 binding did not require sumoylation. Both mutations dysregulated GATA-1 chromatin occupancy at select sites, FOG-1-dependent gene expression, and were rescued by tethering SUMO-1. While FOG-1- and SUMO-1-dependent genes migrated away from the nuclear periphery upon erythroid maturation, FOG-1- and SUMO-1-independent genes persisted at the periphery. These results illustrate a mechanism that controls trans-acting factor function in a locus-specific manner, and differentially regulated members of the target gene ensemble reside in distinct subnuclear compartments.
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Affiliation(s)
- Hsiang-Ying Lee
- University of Wisconsin School of Medicine and Public Health, Wisconsin Institutes for Medical Research, Madison, 53705, USA
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105
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Boidot R, Végran F, Jacob D, Chevrier S, Cadouot M, Feron O, Solary E, Lizard-Nacol S. The transcription factor GATA-1 is overexpressed in breast carcinomas and contributes to survivin upregulation via a promoter polymorphism. Oncogene 2010; 29:2577-84. [DOI: 10.1038/onc.2009.525] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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106
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Huang LJ, Shen YM, Bulut GB. Advances in understanding the pathogenesis of primary familial and congenital polycythaemia. Br J Haematol 2010; 148:844-52. [PMID: 20096014 DOI: 10.1111/j.1365-2141.2009.08069.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Primary familial and congenital polycythemia (PFCP) is an autosomal-dominant proliferative disorder characterized by erythrocytosis and hypersensitivity of erythroid progenitors to erythropoietin (Epo). Several lines of evidence suggest a causal role of truncated erythropoietin receptor (EpoR) in this disease. In this review, we discuss PFCP in the context of erythrocytosis and EpoR signalling. We focus on recent studies describing mechanisms underlying Epo-dependent EpoR down-regulation. One mechanism depends on internalization mediated through the p85 regulatory subunit of the Phosphoinositide 3-Kinase, and the other utilizes ubiquitin-based proteasomal degradation. Truncated PFCP EpoRs are not properly down-regulated upon stimulation, underscoring the importance of these mechanisms in the pathogenesis of PFCP.
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Affiliation(s)
- Lily J Huang
- Department of Cell Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9039, USA.
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107
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Venkatesan B, Prabhu SD, Venkatachalam K, Mummidi S, Valente AJ, Clark RA, Delafontaine P, Chandrasekar B. WNT1-inducible signaling pathway protein-1 activates diverse cell survival pathways and blocks doxorubicin-induced cardiomyocyte death. Cell Signal 2010; 22:809-20. [PMID: 20074638 DOI: 10.1016/j.cellsig.2010.01.005] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 01/02/2010] [Accepted: 01/05/2010] [Indexed: 10/20/2022]
Abstract
The anthracycline antibiotic doxorubicin (DOX) is a potent cancer chemotherapeutic agent that exerts both acute and chronic cardiotoxicity. Here we show that in adult mouse cardiomyocytes, DOX activates (i) the pro-apoptotic p53, (ii) p38MAPK and JNK, (iii) Bax translocation, (iv) cytochrome c release, and (v) caspase 3. Further, it (vi) inhibits expression of anti-apoptotic Akt, Bcl-2 and Bcl-xL, and (vii) induces internucleosomal degradation and cell death. WNT1-inducible signaling pathway protein-1 (WISP1), a CCN family member and a matricellular protein, inhibits DOX-mediated cardiomyocyte death. WISP1 inhibits DOX-induced p53 activation, p38 MAPK and JNK phosphorylation, Bax translocation to mitochondria, and cytochrome c release into cytoplasm. Additionally, WISP1 reverses DOX-induced suppression of Bcl-2 and Bcl-xL expression and Akt inhibition. The pro-survival effects of WISP1 were recapitulated by the forced expression of mutant p53, wild-type Bcl-2, wild-type Bcl-xL, or constitutively active Akt prior to DOX treatment. WISP1 also induces the pro-survival factor Survivin via PI3K/Akt signaling. Overexpression of wild-type, but not mutant Survivin, blunts DOX cytotoxicity. Further, WISP1 stimulates PI3K-Akt-dependent GSK3beta phosphorylation and beta-catenin nuclear translocation. Importantly, WISP1 induces its own expression. Together, these results provide important insights into the cytoprotective effects of WISP1 in cardiomyocytes, and suggest a potential therapeutic role for WISP1 in DOX-induced cardiotoxicity.
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Affiliation(s)
- Balachandar Venkatesan
- Heart and Vascular Institute, Tulane University School of Medicine, New Orleans, LA 70112, United States
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108
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Integrating extrinsic and intrinsic cues into a minimal model of lineage commitment for hematopoietic progenitors. PLoS Comput Biol 2009; 5:e1000518. [PMID: 19911036 PMCID: PMC2736398 DOI: 10.1371/journal.pcbi.1000518] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Accepted: 08/25/2009] [Indexed: 02/08/2023] Open
Abstract
Autoregulation of transcription factors and cross-antagonism between lineage-specific transcription factors are a recurrent theme in cell differentiation. An equally prevalent event that is frequently overlooked in lineage commitment models is the upregulation of lineage-specific receptors, often through lineage-specific transcription factors. Here, we use a minimal model that combines cell-extrinsic and cell-intrinsic elements of regulation in order to understand how both instructive and stochastic events can inform cell commitment decisions in hematopoiesis. Our results suggest that cytokine-mediated positive receptor feedback can induce a “switch-like” response to external stimuli during multilineage differentiation by providing robustness to both bipotent and committed states while protecting progenitors from noise-induced differentiation or decommitment. Our model provides support to both the instructive and stochastic theories of commitment: cell fates are ultimately driven by lineage-specific transcription factors, but cytokine signaling can strongly bias lineage commitment by regulating these inherently noisy cell-fate decisions with complex, pertinent behaviors such as ligand-mediated ultrasensitivity and robust multistability. The simulations further suggest that the kinetics of differentiation to a mature cell state can depend on the starting progenitor state as well as on the route of commitment that is chosen. Lastly, our model shows good agreement with lineage-specific receptor expression kinetics from microarray experiments and provides a computational framework that can integrate both classical and alternative commitment paths in hematopoiesis that have been observed experimentally. Complex biomolecular interaction pathways in signaling networks can lead to non-intuitive behaviors that can prove critical for the regulation and robustness of biological processes. In this work, we present a signaling topology that can generate dynamic responses that are particularly pertinent to cell commitment in hematopoiesis. Our minimal model explores fundamental questions of instructive signaling that have persisted in cell-fate decisions. We show that even when lineage commitment decisions are inherently noisy, external cytokine signals, amplified by receptor upregulation, can bias the lineage choices of a progenitor cell. The multipotent progenitor, based on its differentiation potential, can exhibit several layers of memory to provide stability to both intermediate and mature states and can potentially bypass canonical intermediate states in generating mature cell types. Thus, our model provides a computational framework that can accommodate both classical and non-classical commitment paths in hematopoiesis.
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109
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Abstract
PURPOSE OF REVIEW Red blood cells (RBCs) transfusion plays a critical role in numerous therapies. Disruption of blood collection by political unrest, natural disasters and emerging infections and implementation of restrictions on the use of erythropoiesis-stimulating agents in cancer may impact blood availability in the near future. These considerations highlight the importance of developing alternative blood products. RECENT FINDINGS Knowledge about the processes that control RBC production has been applied to the establishment of culture conditions allowing ex-vivo generation of RBCs in numbers close to those (2.5 x 10 cells/ml) present in a transfusion, from cord blood, donated blood units or embryonic stem cells. In addition, experimental studies demonstrate that such cells protect mice from lethal bleeding. Therefore, erythroid cells generated ex vivo may be suitable for transfusion provided they can be produced safely in adequate numbers. However, much remains to be done to translate a theoretical production of approximately 2.5 x 10 RBCs in the laboratory into a 'clinical grade production process'. SUMMARY This review summarizes the state-of-the-art in establishing ex-vivo culture conditions for erythroid cells and discusses the most compelling issues to be addressed to translate this progress into a clinical grade transfusion product.
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110
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Abstract
Therapy with erythropoiesis-stimulating agents (ESAs) is associated with well-documented benefits to anemic cancer patients undergoing chemotherapy, most importantly a reduction in the likelihood of needing red cell transfusions. One challenge in supportive cancer care is a relative resistance to ESAs, requiring high doses with a significant rate of nonresponse. Recent advances in our understanding of iron metabolism in patients with chronic illness and the results of clinical trials indicate that parenteral iron improves ESA response in this setting. Another issue is the safety of ESA treatment in cancer patients. There is an increased risk of venous thrombosis that must be considered in clinical decision making. There are also recent data raising concerns that ESAs may enhance tumor progression or decrease patient survival. Although the preponderance of the data suggests that ESAs do not alter survival when used to treat chemotherapy-induced anemia, large well-controlled trials addressing this issue are needed.
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Affiliation(s)
- John A Glaspy
- Division of Hematology-Oncology, Department of Medicine, School of Medicine, University of California, Los Angeles, California 90095, USA.
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111
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Di Giacomo V, Sancilio S, Caravatta L, Rana RA, Di Pietro R, Cataldi A. Regulation of CREB activation by p38 mitogen activated protein kinase during human primary erythroblast differentiation. Int J Immunopathol Pharmacol 2009; 22:679-88. [PMID: 19822084 DOI: 10.1177/039463200902200313] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Among the molecular events underlying erythroid differentiation, we analyzed the signalling pathway leading to cAMP response element binding (CREB) nuclear transcription factor activation. Normal donor blood light density cells differentiated to pro-erythroblasts during the proliferative phase (10 days) of the human erythroblast massive amplification (HEMA) culture, and to orthochromatic erythroblasts, during the differentiation phase (4 additional days) of the culture. Since erythropoietin was present all over the culture, also pro-erythroblasts left in proliferative medium for 14 days continued their maturation without reaching the final steps of differentiation. p38 mitogen activated protein kinase (p38 MAPK) and CREB maximal activation occurred upon 4 days of differentiation induction, whereas a lower activation was detectable in the cells maintained in parallel in proliferative medium (14 days). Interestingly, when SB203580, a specific p38 MAPK inhibitor, was added to the culture the percentage of differentiated cells decreased along with p38 MAPK and CREB phosphorylation. All in all, our results evidence a role for p38 MAPK in activating CREB metabolic pathway in the events leading to erythroid differentiation.
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Affiliation(s)
- V Di Giacomo
- Dipartimento di Biomorfologia, Università G. d'Annunzio, Chieti-Pescara, Italy.
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112
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Mutschler M, Magin AS, Buerge M, Roelz R, Schanne DH, Will B, Pilz IH, Migliaccio AR, Pahl HL. NF-E2 overexpression delays erythroid maturation and increases erythrocyte production. Br J Haematol 2009; 146:203-17. [PMID: 19466964 DOI: 10.1111/j.1365-2141.2009.07742.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The transcription factor Nuclear Factor-Erythroid 2 (NF-E2) is overexpressed in the vast majority of patients with polycythaemia vera (PV). In murine models, NF-E2 overexpression increases proliferation and promotes cellular viability in the absence of erythropoietin (EPO). EPO-independent growth is a hallmark of PV. We therefore hypothesized that NF-E2 overexpression contributes to erythrocytosis, the pathognomonic feature of PV. Consequently, we investigated the effect of NF-E2 overexpression in healthy CD34+ cells. NF-E2 overexpression led to a delay in erythroid maturation, manifested by a belated appearance of glycophorin A-positive erythroid precursors. Maturation delay was similarly observed in primary PV patient erythroid cultures compared to healthy controls. Protracted maturation led to a significant increase in the accumulated number of erythroid cells both in PV cultures and in CD34+ cells overexpressing NF-E2. Similarly, NF-E2 overexpression altered erythroid colony formation, leading to an increase in erythroid burst-forming unit formation. These data indicate that NF-E2 overexpression delays the early phase of erythroid maturation, resulting in an expansion of erythroid progenitors, thereby increasing the number of erythrocytes derived from one CD34+ cell. These data propose a role for NF-E2 in mediating the erythrocytosis of PV.
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Affiliation(s)
- Manuel Mutschler
- Department of Experimental Anaesthesiology, Centre for Clinical Research, University Hospital Freiburg, Freiburg 79106, Germany
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113
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Jia Y, Warin R, Yu X, Epstein R, Noguchi CT. Erythropoietin signaling promotes transplanted progenitor cell survival. FASEB J 2009; 23:3089-99. [PMID: 19417086 DOI: 10.1096/fj.09-130237] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
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 receptor expression, as well as exogenous erythropoietin treatment in myoblasts, provided a survival advantage and protection against apoptosis under serum-starvation conditions. When cultured in differentiation medium, expression of the myogenic regulatory proteins shifted toward early differentiation with increased erythropoietin receptor. Expression of early myogenic differentiation proteins Myf-5 and MyoD increased, while later stage protein myogenin decreased. Transplantation of C2C12 myoblasts overexpressing truncated erythropoietin receptor showed more transplanted cell incorporation into muscle fibers in muscular dystrophy mdx mice. These cells also restored dystrophin protein expression in mdx mice at 6 wk after cell treatment that was further increased with exogenous erythropoietin administration. In summary, enhanced erythropoietin receptor expression promotes transplanted cell survival in a mouse model for myoblast transplantation and provides dystrophin expression in mice with muscular dystrophy.
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Affiliation(s)
- Yi Jia
- Molecular Medicine Branch, NIDDK, National Institutes of Health, Bethesda, MD 20892-1822, USA
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114
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Qamar I, Park E, Gong EY, Lee HJ, Lee K. ARR19 (androgen receptor corepressor of 19 kDa), an antisteroidogenic factor, is regulated by GATA-1 in testicular Leydig cells. J Biol Chem 2009; 284:18021-32. [PMID: 19398553 DOI: 10.1074/jbc.m900896200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
ARR19 (androgen receptor corepressor of 19 kDa), which encodes for a leucine-rich protein, is expressed abundantly in the testis. Further analyses revealed that ARR19 was expressed in Leydig cells, and its expression was differentially regulated during Leydig cell development. Adenovirus-mediated overexpression of ARR19 in Leydig cells inhibited testicular steroidogenesis, down-regulating the expression of steroidogenic enzymes, which suggests that ARR19 is an antisteroidogenic factor. Interestingly, cAMP/luteinizing hormone attenuated ARR19 expression in a fashion similar to that of GATA-1, which was previously reported to be down-regulated by cAMP. Sequence analysis of the Arr19 promoter revealed the presence of two putative GATA-1 binding motifs. Further analyses with 5' deletion and point mutants of putative GATA-1 binding motifs showed that these GATA-1 binding sites were critical for high promoter activity. CREB-binding protein coactivated GATA-1 and markedly increased the activity of the Arr19 promoter. Both GATA-1 and CREB-binding proteins occupied the GATA-1 motifs within the Arr19 promoter, which was repressed by cAMP treatment. Altogether, these findings demonstrate that ARR19 is the target gene of GATA-1 and suggest that ARR19 gene expression in testicular Leydig cells is regulated by luteinizing hormone/cAMP signaling via the control of GATA-1 expression, resulting in the control of testicular steroidogenesis.
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Affiliation(s)
- Imteyaz Qamar
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, Republic of Korea
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115
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Ligand-induced EpoR internalization is mediated by JAK2 and p85 and is impaired by mutations responsible for primary familial and congenital polycythemia. Blood 2009; 113:5287-97. [PMID: 19336760 DOI: 10.1182/blood-2008-09-179572] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Epo-induced endocytosis of EpoR plays important roles in the down-regulation of EpoR signaling and is the primary means that regulates circulating Epo concentrations. Here we show that cell-surface EpoR is internalized via clathrin-mediated endocytosis. Both JAK2 kinase activity and EpoR cytoplasmic tyrosines are important for ligand-dependent EpoR internalization. Phosphorylated Y429, Y431, and Y479 in the EpoR cytoplasmic domain bind p85 subunit of PI3 kinase on Epo stimulation and individually are sufficient to mediate Epo-dependent EpoR internalization. Knockdown of p85alpha and p85beta or expression of their dominant-negative forms, but not inhibition of PI3 kinase activity, dramatically impaired EpoR internalization, indicating that p85alpha and p85beta may recruit proteins in the endocytic machinery on Epo stimulation. Furthermore, mutated EpoRs from primary familial and congenital polycythemia (PFCP) patients lacking the 3 important tyrosines do not bind p85 or internalize on stimulation. Addition of residues encompassing Y429 and Y431 to these truncated receptors restored p85beta binding and Epo sensitivity. Our results identify a novel PI3 kinase activity-independent function of p85 in EpoR internalization and support a model that defects of internalization in truncated EpoRs from PFCP patients contribute to Epo hypersensitivity and prolonged signaling.
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116
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Abstract
The approach to a patient with erythrocytosis is greatly simplified by assessing the clonality of the process upfront. In this regard, there has been a dramatic shift toward genetic testing and away from traditional tests, such as measurement of red cell mass. Clonal erythrocytosis is the diagnostic feature of polycythemia vera (PV) and is almost always associated with a JAK2 mutation (JAK2V617F or exon 12). All other scenarios represent non-clonal erythrocytosis, often referred to as secondary erythrocytosis. Serum erythropoietin (Epo) level is usually normal or elevated in secondary erythrocytosis and subnormal in PV. Therefore, in a patient with acquired erythrocytosis, it is reasonable to begin the diagnostic work-up with peripheral blood JAK2 mutation analysis and serum Epo measurement to distinguish PV from secondary erythrocytosis. Conversely, the patient with life-long erythrocytosis is more likely to suffer from congenital polycythemia and should therefore be evaluated for germline mutations that result in enhanced Epo effect (for example, Epo receptor mutations), altered intracellular oxygen sensing (for example, mutations involving the von Hippel-Lindau tumor suppressor gene) or decreased P50 (for example, high-oxygen-affinity hemoglobinopathy). The order of tests in this instance depends on the clinical scenario and serum Epo level.
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117
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Miller SA, Weinmann AS. Common themes emerge in the transcriptional control of T helper and developmental cell fate decisions regulated by the T-box, GATA and ROR families. Immunology 2009; 126:306-15. [PMID: 19302139 PMCID: PMC2669811 DOI: 10.1111/j.1365-2567.2008.03040.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Revised: 12/05/2008] [Accepted: 12/05/2008] [Indexed: 01/12/2023] Open
Abstract
Cellular differentiation requires the precise action of lineage-determining transcription factors. In the immune system, CD4(+) T helper cells differentiate into at least three distinct effector lineages, T helper type 1 (Th1), Th2 and Th17, with the fate of the cell at least in part determined by the transcription factors T-box expressed in T cells (T-bet), GATA-3 and retinoid-related orphan receptor gammat (RORgammat), respectively. Importantly, these transcription factors are members of larger families that are required for numerous developmental transitions from early embryogenesis into adulthood. Mutations in members of these transcription factor families are associated with a number of human genetic diseases due to a failure in completing lineage-specification events when the factor is dysregulated. Mechanistically, there are both common and distinct functional activities that are utilized by T-box, GATA and ROR family members to globally alter the cellular gene expression profiles at specific cell fate decision checkpoints. Therefore, understanding the molecular events that contribute to the ability of T-bet, GATA-3 and RORgammat to define T helper cell lineages can provide valuable information relevant to the establishment of other developmental systems and, conversely, information from diverse developmental systems may provide unexpected insights into the molecular mechanisms utilized in T helper cell differentiation.
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118
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Linking anemia to inflammation and cancer: the crucial role of TNFalpha. Biochem Pharmacol 2009; 77:1572-9. [PMID: 19174153 DOI: 10.1016/j.bcp.2008.12.018] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Revised: 12/03/2008] [Accepted: 12/16/2008] [Indexed: 12/18/2022]
Abstract
Erythropoiesis is considered as a multistep and tightly regulated process under the control of a series of cytokines including erythropoietin (Epo). Epo activates specific signaling pathways and leads to activation of key transcription factors such as GATA-1, in order to ensure erythroid differentiation. Deregulation leads to a decreased number of red blood cells, a hemoglobin deficiency, thus a limited oxygen-carrying capacity in the blood. Anemia represents a frequent complication in various diseases such as cancer or inflammatory diseases. It reduces both quality of life and prognosis in patients. Tumor necrosis factor alpha (TNFalpha) was described to be involved in the pathogenesis of inflammation and cancer related anemia. Blood transfusions and erythroid stimulating agents (ESAs) including human recombinant Epo (rhuEpo) are currently used as efficient treatments. Moreover, the recently described conflicting effects of ESAs in distinct studies require further investigations on the molecular mechanisms involved in TNFalpha-caused anemia. The present study aims to evaluate the current knowledge and the importance of the effect of the proinflammatory cytokine TNFalpha on erythropoiesis in inflammatory and malignant conditions.
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119
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Abstract
The BCR-ABL-negative myeloproliferative neoplasms (MPNs), polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF), entered the spotlight in 2005 when the unique somatic acquired JAK2 V617F mutation was described in >95% of PV and in 50% of ET and PMF patients. For the very rare PV patients who do not harbor the JAK2 V617F mutation, exon 12 JAK2 mutants were discovered also to result in activated forms of JAK2. A minority of ET and PMF patients harbor mutations that constitutively activate the thrombopoietin receptor (TpoR). In bone marrow reconstitution models based on retroviral transduction, the phenotype induced by JAK2 V617F is less severe and different from the rapid fatal myelofibrosis induced by TpoR W515L. The reasons for these differences are unknown. Exactly by which mechanism(s) one acquired somatic mutation, JAK2 V617F, can promote three different diseases remains a mystery, although gene dosage and host genetic variation might have important functions. We review the recent progress made in deciphering signaling anomalies in PV, ET and PMF, with an emphasis on the relationship between JAK2 V617F and cytokine receptor signaling and on cross-talk with several other signaling pathways.
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120
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Sigounas G, Salleng KJ, Mehlhop PD, Sigounas DG. Erythropoietin ameliorates chemotherapy-induced fibrosis of the lungs in a preclinical murine model. Int J Cancer 2008; 122:2851-7. [PMID: 18350568 DOI: 10.1002/ijc.23426] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Organ toxicity induced by chemotherapeutic drugs is a serious obstacle in the effective treatment of patients suffering from cancer and autoimmune disease. A strong association exists between pulmonary toxicity, particularly fibrosis, and chemotherapeutic drugs. Attempts have been made to identify compounds capable of suppressing fibrosis. In addition to its erythropoietic activity, erythropoietin (EPO) has been shown to have effects on nonhemopoietic cells. Therefore, we postulated that EPO may exert beneficial effects on lung tissue during chemotherapy. To test our hypothesis, we investigated pulmonary changes caused by bleomycin, a fibrosis-inducing agent, in animals treated with the drug alone and in combination with EPO. Fibrosis, cellular alterations and structural changes were assayed by blind analysis of the lung sections. A 6-fold decrease in the number of prominent endothelial cells--suspected to be indicative of cellular activation and inflammatory response--was observed in lung sections derived from mice treated with bleomycin and EPO compared to animals injected with bleomycin alone (p < 0.008). Additionally, there was twice the number of ICAM1-positive endothelial cells in animals treated with bleomycin alone compared with the number in the bleomycin and EPO-treated group (p < 0.05). Alveolar mononuclear phagocytic hyperplasia was reduced by as much as 100% in animals treated with bleomycin and EPO compared to animals treated with bleomycin alone (p < 0.03). Finally, a 5-fold decrease in interstitial fibrosis was observed in lung sections obtained from animals treated with bleomycin and EPO (p < 0.02). We conclude that EPO can ameliorate drug-induced fibrosis and endothelial damage caused by chemotherapeutic agents.
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Affiliation(s)
- George Sigounas
- Hematology/Oncology Section, Department of Internal Medicine, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA.
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121
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Missiroli S, Etro D, Buontempo F, Ye K, Capitani S, Neri LM. Nuclear translocation of active AKT is required for erythroid differentiation in erythropoietin treated K562 erythroleukemia cells. Int J Biochem Cell Biol 2008; 41:570-7. [PMID: 18694847 DOI: 10.1016/j.biocel.2008.07.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 06/25/2008] [Accepted: 07/10/2008] [Indexed: 11/28/2022]
Abstract
Erythroid differentiation of human erythroleukemia cell line K562 induced by erythropoietin is a complex process that involves modifications at nuclear level, including nuclear translocation of phosphatidyl-inositol 3-kinase. In this work we show that erythropoietin stimulation of K562 cells can induce nuclear translocation of active Akt, a downstream molecule of the phosphatidyl-inositol 3-kinase signaling pathway. Akt shows a peak of activity in whole cell homogenates at earlier stage when compared to the nucleus, which shows a peak delayed of 10 min. Akt increases its intranuclear amount and activity rapidly and transiently in response to EPO. Almost all Akt kinase that translocates to the nucleus shows a marked phosphorylation on serine 473. Nuclear enzyme translocation is blocked by the phosphatidyl-inositol 3-kinase inhibitor Ly294002 or Wortmannin. The specific Akt pharmacological inhibitor VI, VII and VIII that act as blocking enzyme activation inhibited translocation as well, whereas Akt inhibitor IX, that inhibits Akt activity, did not block Akt nuclear translocation. When cells were treated by means of siRNA sequences or with the Akt inhibitors the differentiation process was arrested, thus showing the requirement of the nuclear translocation of the active enzyme to differentiate. These findings strongly suggest that the intranuclear translocation of active Akt kinase represents an important step in the signaling pathway that mediates erythropoietin-induced erythroid differentiation.
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Affiliation(s)
- Silvia Missiroli
- Dipartimento di Morfologia ed Embriologia, Sezione di Anatomia Umana, Signal Transduction Unit, Universita' di Ferrara, Ferrara, Italy
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122
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Positive receptor feedback during lineage commitment can generate ultrasensitivity to ligand and confer robustness to a bistable switch. Biophys J 2008; 95:1575-89. [PMID: 18469073 DOI: 10.1529/biophysj.107.120600] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cytokines and lineage-specific transcription factors are critical molecular effectors for terminal differentiation during hematopoiesis. Intrinsic transcription factor activity is often believed to drive commitment and differentiation, whereas cytokine receptor signals have been implicated in the regulation of cell proliferation, survival, and differentiation. In erythropoiesis, recent experimental findings provide direct evidence that erythropoietin (Epo) can generate commitment cues via the erythropoietin receptor (EpoR); specifically, EpoR signaling leads to activation of the transcription factor GATA-1, which then triggers transcription of erythrocyte-specific genes. In particular, activated GATA-1 induces two positive feedback loops in the system through the enhanced expression of both inactive GATA-1 and EpoR, the latter of which is externally regulatable by Epo. Based upon this network architecture, we present a mathematical model of GATA-1 activation by EpoR, which bidirectionally links a lineage-specific receptor and transcription factor. Our deterministic model offers insight into stimulus-response relationships between Epo and several downstream effectors. In addition to the survival signals that EpoR provides, steady-state analysis of our model suggests that receptor upregulation during lineage commitment can also generate ultrasensitivity to Epo and bistability in GATA-1 activity. These system-level properties can induce a switch-like characteristic during differentiation and provide robustness to the mature state. The topology also suggests a novel mechanism for achieving robust bistability in a purely deterministic manner without molecular cooperativity. The analytical solution of a generalized, minimal model is provided and the significance of each of the two positive feedback loops is elucidated through bifurcation analysis. This network topology, or variations thereof, may link other receptor-transcription factor pairs and may therefore be of general relevance in cellular decision-making.
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123
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Yalcin S, Zhang X, Luciano JP, Mungamuri SK, Marinkovic D, Vercherat C, Sarkar A, Grisotto M, Taneja R, Ghaffari S. Foxo3 is essential for the regulation of ataxia telangiectasia mutated and oxidative stress-mediated homeostasis of hematopoietic stem cells. J Biol Chem 2008; 283:25692-25705. [PMID: 18424439 DOI: 10.1074/jbc.m800517200] [Citation(s) in RCA: 193] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Unchecked accumulation of reactive oxygen species (ROS) compromises maintenance of hematopoietic stem cells. Regulation of ROS by the tumor suppressor protein ataxia telangiectasia mutated (ATM) is critical for preserving the hematopoietic stem cell pool. In this study we demonstrate that the Foxo3 member of the Forkhead Box O (FoxO) family of transcription factors is essential for normal ATM expression. In addition, we show that loss of Foxo3 leads to defects in hematopoietic stem cells, and these defects result from an overaccumulation of ROS. Foxo3 suppression of ROS in hematopoietic stem cells is mediated partly by regulation of ATM expression. We identify ROS-independent modulations of ATM and p16(INK4a) and ROS-mediated activation of p53/p21(CIP1/WAF1/Sdi1) tumor suppressor pathways as major contributors to Foxo3-null hematopoietic stem cells defects. Our studies demonstrate that Foxo3 represses ROS in part via regulation of ATM and that this repression is required for maintenance of the hematopoietic stem cell pool.
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Affiliation(s)
- Safak Yalcin
- Department of Gene and Cell Medicine, New York, New York 10029
| | - Xin Zhang
- Department of Gene and Cell Medicine, New York, New York 10029
| | - Julia P Luciano
- Department of Gene and Cell Medicine, New York, New York 10029
| | | | | | - Cécile Vercherat
- Department of Developmental and Regenerative Biology, New York, New York 10029
| | - Abby Sarkar
- Department of Gene and Cell Medicine, New York, New York 10029
| | - Marcos Grisotto
- Department of Gene and Cell Medicine, New York, New York 10029
| | - Reshma Taneja
- Department of Developmental and Regenerative Biology, New York, New York 10029; Black Family Stem Cell Institute, New York, New York 10029
| | - Saghi Ghaffari
- Department of Gene and Cell Medicine, New York, New York 10029; Department of Developmental and Regenerative Biology, New York, New York 10029; Black Family Stem Cell Institute, New York, New York 10029; Department of Medicine Division of Hematology, Oncology, Mount Sinai School of Medicine, New York, New York 10029.
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124
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Geron I, Abrahamsson AE, Barroga CF, Kavalerchik E, Gotlib J, Hood JD, Durocher J, Mak CC, Noronha G, Soll RM, Tefferi A, Kaushansky K, Jamieson CHM. Selective inhibition of JAK2-driven erythroid differentiation of polycythemia vera progenitors. Cancer Cell 2008; 13:321-30. [PMID: 18394555 DOI: 10.1016/j.ccr.2008.02.017] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2007] [Revised: 12/26/2007] [Accepted: 02/27/2008] [Indexed: 10/22/2022]
Abstract
Polycythemia Vera (PV) is a myeloproliferative disorder (MPD) that is commonly characterized by mutant JAK2 (JAK2V617F) signaling, erythrocyte overproduction, and a propensity for thrombosis, progression to myelofibrosis, or acute leukemia. In this study, JAK2V617F expression by human hematopoietic progenitors promoted erythroid colony formation and erythroid engraftment in a bioluminescent xenogeneic immunocompromised mouse transplantation model. A selective JAK2 inhibitor, TG101348 (300 nM), significantly inhibited JAK2V617F+ progenitor-derived colony formation as well as engraftment (120 mg/kg) in xenogeneic transplantation studies. TG101348 treatment decreased GATA-1 expression, which is associated with erythroid-skewing of JAK2V617F+ progenitor differentiation, and inhibited STAT5 as well as GATA S310 phosphorylation. Thus, TG101348 may be an effective inhibitor of JAK2V617F+ MPDs in clinical trials.
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Affiliation(s)
- Ifat Geron
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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125
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Robey TE, Saiget MK, Reinecke H, Murry CE. Systems approaches to preventing transplanted cell death in cardiac repair. J Mol Cell Cardiol 2008; 45:567-81. [PMID: 18466917 DOI: 10.1016/j.yjmcc.2008.03.009] [Citation(s) in RCA: 302] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2008] [Revised: 02/20/2008] [Accepted: 03/06/2008] [Indexed: 12/26/2022]
Abstract
Stem cell transplantation may repair the injured heart, but tissue regeneration is limited by death of transplanted cells. Most cell death occurs in the first few days post-transplantation, likely from a combination of ischemia, anoikis and inflammation. Interventions known to enhance transplanted cell survival include heat shock, over-expressing anti-apoptotic proteins, free radical scavengers, anti-inflammatory therapy and co-delivery of extracellular matrix molecules. Combinatorial use of such interventions markedly enhances graft cell survival, but death still remains a significant problem. We review these challenges to cardiac cell transplantation and present an approach to systematically address them. Most anti-death studies use histology to assess engraftment, which is time- and labor-intensive. To increase throughput, we developed two biochemical approaches to follow graft viability in the mouse heart. The first relies on LacZ enzymatic activity to track genetically modified cells, and the second quantifies human genomic DNA content using repetitive Alu sequences. Both show linear relationships between input cell number and biochemical signal, but require correction for the time lag between cell death and loss of signal. Once optimized, they permit detection of as few as 1 graft cell in 40,000 host cells. Pro-survival effects measured biochemically at three days predict long-term histological engraftment benefits. These methods permitted identification of carbamylated erythropoietin (CEPO) as a pro-survival factor for human embryonic stem cell-derived cardiomyocyte grafts. CEPO's effects were additive to heat shock, implying independent survival pathways. This system should permit combinatorial approaches to enhance graft viability in a fraction of the time required for conventional histology.
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Affiliation(s)
- Thomas E Robey
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
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126
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Wozniak RJ, Bresnick EH. Chapter 3 Epigenetic Control of Complex Loci During Erythropoiesis. Curr Top Dev Biol 2008; 82:55-83. [DOI: 10.1016/s0070-2153(07)00003-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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127
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Abstract
Transcriptional networks orchestrate fundamental biological processes, including hematopoiesis, in which hematopoietic stem cells progressively differentiate into specific progenitors cells, which in turn give rise to the diverse blood cell types. Whereas transcription factors recruit coregulators to chromatin, leading to targeted chromatin modification and recruitment of the transcriptional machinery, many questions remain unanswered regarding the underlying molecular mechanisms. Furthermore, how diverse cell type-specific transcription factors function cooperatively or antagonistically in distinct cellular contexts is poorly understood, especially since genes in higher eukaryotes commonly encompass broad chromosomal regions (100 kb and more) and are littered with dispersed regulatory sequences. In this article, we describe an important set of transcription factors and coregulators that control erythropoiesis and highlight emerging transcriptional mechanisms and principles. It is not our intent to comprehensively survey all factors implicated in the transcriptional control of erythropoiesis, but rather to underscore specific mechanisms, which have potential to be broadly relevant to transcriptional control in diverse systems.
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128
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Ghinassi B, Verrucci M, Jelicic K, Di Noia A, Migliaccio G, Migliaccio AR. Interleukin-3 and erythropoietin cooperate in the regulation of the expression of erythroid-specific transcription factors during erythroid differentiation. Exp Hematol 2007; 35:735-47. [PMID: 17577923 DOI: 10.1016/j.exphem.2007.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
OBJECTIVE To characterize how interleukin-3 and erythropoietin regulate cell fate by modulating the expression of lineage-specific transcription factors. METHODS This study analyzed mRNA and protein levels, gene transcription rates, and mRNA and protein stabilities of erythroid-specific transcription factors in lineage-restricted cells derived from the 32D cell line cultured either in interleukin-3 or erythropoietin. RESULTS Erythroid 32D subclones expressed levels of Idl, Gata-2, and Scl comparable and levels of Eklf and Gata-1 higher than those expressed by myeloid subclones. While maintained in interleukin-3, erythroid cells remained immature despite their high expression of Gata-1, Gata-2, Scl, Eklf, and Idl. Switching the erythroid cells to erythropoietin induced cell maturation (within 48 hours) and reduced expression of Gata-2 and Idl (in 24 hours) but did not alter the expression of Gata-1. The effects of interleukin-3 were mostly mediated by increases in transcription rates (Scl and Gata-2), and that of erythropoietin was apparently due to increased mRNA and protein (Gata-1, Scl, and Eklf) stability. In particular, erythropoietin increased the stability of the processed and transcriptionally more active form of GATA-1 protein. CONCLUSIONS These results suggest that interleukin-3 and erythropoietin cooperate to establish the lineage-specific transcription factor milieu of erythroid cells: interleukin-3 regulates mainly gene transcription and erythropoietin consistently increases mRNA and protein stability.
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Affiliation(s)
- Barbara Ghinassi
- Department of Hematology, Oncology and Molecular Medicine, Istituto Superiore Sanità, Rome, Italy
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129
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130
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Svensson E, Vidovic K, Lassen C, Richter J, Olofsson T, Fioretos T, Gullberg U. Deregulation of the Wilms' tumour gene 1 protein (WT1) by BCR/ABL1 mediates resistance to imatinib in human leukaemia cells. Leukemia 2007; 21:2485-94. [PMID: 17728783 DOI: 10.1038/sj.leu.2404924] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The Wilms' tumour gene 1 (WT1) protein is highly expressed in most leukaemias. Co-expression of WT1 and the fusion protein AML1-ETO in mice rapidly induces acute myeloid leukaemia (AML). Mechanisms behind expression of WT1, as well as consequences thereof, are still unclear. Here, we report that the fusion protein BCR/ABL1 increases expression of WT1 mRNA and protein via the phosphatidylinositol-3 kinase (PI3K)-Akt pathway. Inhibition of BCR/ABL1 or PI3K activity strongly suppressed transcription from WT1 promoter/enhancer reporters. Forced expression of BCR/ABL1 in normal human progenitor CD34+ cells increased WT1 mRNA and protein, further supporting the notion of BCR/ABL1-driven expression of WT1 in human haematopoietic cells. Forced expression of WT1 in K562 cells provided protection against cytotoxic effects of the ABL1 tyrosine kinase inhibitor imatinib, as judged by effects on viability measured by trypan blue exclusion, metabolic activity, annexin V and DAPI (4', 6-diamidino-2-phenylindole) staining. None of the isoforms provided any detectable protection against apoptosis induced by arsenic trioxide and only very weak protection against etoposide, indicating that WT1 interferes with specific apoptotic signalling pathways. Our data demonstrate that WT1 expression is induced by oncogenic signalling from BCR/ABL1 and that WT1 contributes to resistance against apoptosis induced by imatinib.
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MESH Headings
- Apoptosis/drug effects
- Benzamides
- Cell Line, Tumor/drug effects
- Cell Line, Tumor/metabolism
- Cells, Cultured/drug effects
- Cells, Cultured/metabolism
- Chromones/pharmacology
- Drug Resistance, Neoplasm/genetics
- Etoposide/pharmacology
- Fusion Proteins, bcr-abl/antagonists & inhibitors
- Fusion Proteins, bcr-abl/physiology
- Gene Expression Regulation, Leukemic
- Genes, Wilms Tumor
- Hematopoietic Stem Cells/drug effects
- Hematopoietic Stem Cells/metabolism
- Humans
- Imatinib Mesylate
- Inositol/analogs & derivatives
- Inositol/pharmacology
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology
- Morpholines/pharmacology
- Neoplasm Proteins/antagonists & inhibitors
- Neoplasm Proteins/genetics
- Neoplasm Proteins/physiology
- Phosphatidylinositol 3-Kinases/physiology
- Phosphoinositide-3 Kinase Inhibitors
- Piperazines/pharmacology
- Protein Kinase Inhibitors/pharmacology
- Proto-Oncogene Proteins c-akt/antagonists & inhibitors
- Proto-Oncogene Proteins c-akt/physiology
- Pyrimidines/pharmacology
- RNA, Neoplasm/biosynthesis
- RNA, Neoplasm/genetics
- Recombinant Fusion Proteins/physiology
- Signal Transduction/drug effects
- Transduction, Genetic
- WT1 Proteins/biosynthesis
- WT1 Proteins/physiology
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Affiliation(s)
- E Svensson
- Division of Hematology and Transfusion Medicine, Faculty of Medicine, Lund University, Lund, Sweden
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131
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Leung WH, Bolland S. The inositol 5'-phosphatase SHIP-2 negatively regulates IgE-induced mast cell degranulation and cytokine production. THE JOURNAL OF IMMUNOLOGY 2007; 179:95-102. [PMID: 17579026 DOI: 10.4049/jimmunol.179.1.95] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Aggregation of the high-affinity IgE receptor (FcepsilonRI) on mast cells initiates signaling pathways leading to degranulation and cytokine release. It has been reported that SHIP-1 negatively regulates FcepsilonRI-triggered pathways but it is unknown whether its homologous protein SHIP-2 has the same function. We have used a lentiviral-based RNA interference technique to obtain SHIP-2 knockdown bone marrow-derived mast cells (BMMCs) and have found that elimination of SHIP-2 results in both increased mast cell degranulation and cytokine (IL-4 and IL-13) gene expression upon FcepsilonRI stimulation. Elimination of SHIP-2 from BMMCs has no effect on FcepsilonRI-triggered calcium flux, tyrosine phosphorylation of MAPKs or in actin depolymerization following activation. Rather, we observe that absence of SHIP-2 results in increased activation of the small GTPase Rac-1 and in enhanced microtubule polymerization upon FcepsilonRI engagement. Coimmunoprecipitation experiments in rat basophilic leukemia (RBL 2H3) cells show that SHIP-2 interacts with the FcepsilonRI beta-chain, Gab2 and Lyn and that unlike SHIP-1, it does not associate with SHC in mast cells. Our results report a negative regulatory role of SHIP-2 on mast cell activation that is calcium independent and distinct from the regulation by SHIP-1.
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Affiliation(s)
- Wai-Hang Leung
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12441 Parklawn Drive, Rockville, MD 20852, USA
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132
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Marinkovic D, Zhang X, Yalcin S, Luciano JP, Brugnara C, Huber T, Ghaffari S. Foxo3 is required for the regulation of oxidative stress in erythropoiesis. J Clin Invest 2007; 117:2133-44. [PMID: 17671650 PMCID: PMC1934587 DOI: 10.1172/jci31807] [Citation(s) in RCA: 239] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Accepted: 05/08/2007] [Indexed: 12/22/2022] Open
Abstract
Erythroid cells accumulate hemoglobin as they mature and as a result are highly prone to oxidative damage. However, mechanisms of transcriptional control of antioxidant defense in erythroid cells have thus far been poorly characterized. We observed that animals deficient in the forkhead box O3 (Foxo3) transcription factor died rapidly when exposed to erythroid oxidative stress-induced conditions, while wild-type mice showed no decreased viability. In view of this striking finding, we investigated the potential role of Foxo3 in the regulation of ROS in erythropoiesis. Foxo3 expression, nuclear localization, and transcriptional activity were all enhanced during normal erythroid cell maturation. Foxo3-deficient erythrocytes exhibited decreased expression of ROS scavenging enzymes and had a ROS-mediated shortened lifespan and evidence of oxidative damage. Furthermore, loss of Foxo3 induced mitotic arrest in erythroid precursor cells, leading to a significant decrease in the rate of in vivo erythroid maturation. We identified ROS-mediated upregulation of p21(CIP1/WAF1/Sdi1) (also known as Cdkn1a) as a major contributor to the interference with cell cycle progression in Foxo3-deficient erythroid precursor cells. These findings establish an essential nonredundant function for Foxo3 in the regulation of oxidative stress, cell cycle, maturation, and lifespan of erythroid cells. These results may have an impact on the understanding of human disorders in which ROS play a role.
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Affiliation(s)
- Dragan Marinkovic
- Department of Gene and Cell Medicine, Mount Sinai School of Medicine, New York, New York, USA.
Department of Laboratory Medicine, Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Black Family Stem Cell Institute,
Department of Molecular, Cell, and Developmental Biology, and
Department of Medicine, Division of Hematology and Medical Oncology, Mount Sinai School of Medicine, New York, New York, USA
| | - Xin Zhang
- Department of Gene and Cell Medicine, Mount Sinai School of Medicine, New York, New York, USA.
Department of Laboratory Medicine, Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Black Family Stem Cell Institute,
Department of Molecular, Cell, and Developmental Biology, and
Department of Medicine, Division of Hematology and Medical Oncology, Mount Sinai School of Medicine, New York, New York, USA
| | - Safak Yalcin
- Department of Gene and Cell Medicine, Mount Sinai School of Medicine, New York, New York, USA.
Department of Laboratory Medicine, Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Black Family Stem Cell Institute,
Department of Molecular, Cell, and Developmental Biology, and
Department of Medicine, Division of Hematology and Medical Oncology, Mount Sinai School of Medicine, New York, New York, USA
| | - Julia P. Luciano
- Department of Gene and Cell Medicine, Mount Sinai School of Medicine, New York, New York, USA.
Department of Laboratory Medicine, Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Black Family Stem Cell Institute,
Department of Molecular, Cell, and Developmental Biology, and
Department of Medicine, Division of Hematology and Medical Oncology, Mount Sinai School of Medicine, New York, New York, USA
| | - Carlo Brugnara
- Department of Gene and Cell Medicine, Mount Sinai School of Medicine, New York, New York, USA.
Department of Laboratory Medicine, Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Black Family Stem Cell Institute,
Department of Molecular, Cell, and Developmental Biology, and
Department of Medicine, Division of Hematology and Medical Oncology, Mount Sinai School of Medicine, New York, New York, USA
| | - Tara Huber
- Department of Gene and Cell Medicine, Mount Sinai School of Medicine, New York, New York, USA.
Department of Laboratory Medicine, Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Black Family Stem Cell Institute,
Department of Molecular, Cell, and Developmental Biology, and
Department of Medicine, Division of Hematology and Medical Oncology, Mount Sinai School of Medicine, New York, New York, USA
| | - Saghi Ghaffari
- Department of Gene and Cell Medicine, Mount Sinai School of Medicine, New York, New York, USA.
Department of Laboratory Medicine, Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Black Family Stem Cell Institute,
Department of Molecular, Cell, and Developmental Biology, and
Department of Medicine, Division of Hematology and Medical Oncology, Mount Sinai School of Medicine, New York, New York, USA
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133
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Rimmelé P, Kosmider O, Mayeux P, Moreau-Gachelin F, Guillouf C. Spi-1/PU.1 participates in erythroleukemogenesis by inhibiting apoptosis in cooperation with Epo signaling and by blocking erythroid differentiation. Blood 2007; 109:3007-14. [PMID: 17132716 DOI: 10.1182/blood-2006-03-006718] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Overexpression of the transcription factor Spi-1/PU.1 in mice leads to acute erythroleukemia characterized by a differentiation block at the proerythroblastic stage. In this study, we made use of a new cellular system allowing us to reach graded expression of Spi-1 in preleukemic cells to dissect mechanisms of Spi-1/ PU-1 in erythroleukemogenesis. This system is based on conditional production of 1 or 2 spi-1-interfering RNAs stably inserted into spi-1 transgenic proerythroblasts. We show that Spi-1 knock-down was sufficient to reinstate the erythroid differentiation program. This differentiation process was associated with an exit from the cell cycle. Evidence is provided that in the presence of erythropoietin (Epo), Spi-1 displays an antiapoptotic role that is independent of its function in blocking erythroid differentiation. Apoptosis inhibited by Spi-1 did not involve activation of the Fas/FasL signaling pathway nor a failure to activate Epo receptor (EpoR). Furthermore, we found that reducing the Spi-1 level yields to ERK dephosphorylation and increased phosphorylation of AKT and STAT5, suggesting that Spi-1 may affect major signaling pathways downstream of the EpoR in erythroid cells. These findings reveal 2 distinct roles for Spi-1 during erythroleukemogenesis: Spi-1 blocks the erythroid differentiation program and acts to impair apoptotic death in cooperation with an Epo signaling.
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MESH Headings
- Animals
- Apoptosis/physiology
- Base Sequence
- Cell Cycle/physiology
- Cell Differentiation
- Erythroblasts/pathology
- Erythroblasts/physiology
- Erythropoiesis/physiology
- Erythropoietin/physiology
- Humans
- Leukemia, Erythroblastic, Acute/etiology
- Leukemia, Erythroblastic, Acute/genetics
- Leukemia, Erythroblastic, Acute/pathology
- Leukemia, Erythroblastic, Acute/physiopathology
- Mice
- Mice, Transgenic
- Proto-Oncogene Proteins/antagonists & inhibitors
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins/physiology
- RNA, Small Interfering/genetics
- Receptors, Erythropoietin/physiology
- Signal Transduction/physiology
- Trans-Activators/antagonists & inhibitors
- Trans-Activators/genetics
- Trans-Activators/physiology
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Affiliation(s)
- Pauline Rimmelé
- Institut Curie, Institut National de la Santé et de la Recherche Médicale (INSERM) Unite 528, Paris, France
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134
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Noguchi CT, Asavaritikrai P, Teng R, Jia Y. Role of erythropoietin in the brain. Crit Rev Oncol Hematol 2007; 64:159-71. [PMID: 17482474 PMCID: PMC2083122 DOI: 10.1016/j.critrevonc.2007.03.001] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Revised: 01/12/2007] [Accepted: 03/14/2007] [Indexed: 11/21/2022] Open
Abstract
Multi-tissue erythropoietin receptor (EPO-R) expression provides for erythropoietin (EPO) activity beyond its known regulation of red blood cell production. This review highlights the role of EPO and EPO-R in brain development and neuroprotection. EPO-R brain expression includes neural progenitor cells (NPC), neurons, glial cells and endothelial cells. EPO is produced in brain in a hypoxia sensitive manner, stimulates NPC proliferation and differentiation, and neuron survival, and contributes to ischemic preconditioning. Mice lacking EPO or EPO-R exhibit increased neural cell apoptosis during development before embryonic death due to severe anemia. EPO administration provides neural protection in animal models of brain ischemia and trauma, reducing the extent of injury and damage. Intrinsic EPO production in brain and EPO stimulation of endothelial cells contribute to neuroprotection and these are of particular importance since only low levels of EPO appear to cross the blood-brain barrier when administered at high dose intravenously. The therapeutic potential of EPO for brain ischemia/trauma and neurodegenerative diseases has shown promise in early clinical trial and awaits further validation.
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Affiliation(s)
- Constance Tom Noguchi
- Molecular Medicine Branch, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892-1822, USA.
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135
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Bone HK, Welham MJ. Phosphoinositide 3-kinase signalling regulates early development and developmental haemopoiesis. J Cell Sci 2007; 120:1752-62. [PMID: 17456549 PMCID: PMC1906847 DOI: 10.1242/jcs.003772] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Phosphoinositide 3-kinase (PI3K)-dependent signalling regulates a wide variety of cellular functions including proliferation and differentiation. Disruption of class I(A) PI3K isoforms has implicated PI3K-mediated signalling in development of the early embryo and lymphohaemopoietic system. We have used embryonic stem (ES) cells as an in vitro model to study the involvement of PI3K-dependent signalling during early development and haemopoiesis. Both pharmacological inhibition and genetic manipulation of PI3K-dependent signalling demonstrate that PI3K-mediated signals, most likely via 3-phosphoinositide-dependent protein kinase 1 (PDK1), are required for proliferation of cells within developing embryoid bodies (EBs). Surprisingly, the haemopoietic potential of EB-derived cells was not blocked upon PI3K inhibition but rather enhanced, correlating with modest increases in expression of haemopoietic marker genes. By contrast, PDK1-deficient EB-derived progeny failed to generate terminally differentiated haemopoietic lineages. This deficiency appeared to be due to a requirement for PI3K signalling during the proliferative phase of blast-colony-forming cell (BL-CFC) expansion, rather than as a result of effects on differentiation per se. We also demonstrate that PI3K-dependent signalling is required for optimal generation of erythroid and myeloid progenitors and their differentiation into mature haemopoietic colony types. These data demonstrate that PI3K-dependent signals play important roles at different stages of haemopoietic development.
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Affiliation(s)
- Heather K Bone
- Department of Pharmacy and Pharmacology, Centre for Regenerative Medicine, University of Bath, Claverton Down, Bath, BA2 7AY, UK
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136
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Andrieux LO, Fautrel A, Bessard A, Guillouzo A, Baffet G, Langouët S. GATA-1 is essential in EGF-mediated induction of nucleotide excision repair activity and ERCC1 expression through ERK2 in human hepatoma cells. Cancer Res 2007; 67:2114-23. [PMID: 17332341 DOI: 10.1158/0008-5472.can-06-3821] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The nucleotide excision repair (NER) pathway and its leading gene excision-repair cross-complementary 1 (ERCC1) have been shown to be up-regulated in hepatocellular carcinomas even in the absence of treatment with chemotherapeutics. The aim of this study was to determine the mechanism involved in NER regulation during the liver cell growth observed in hepatocellular carcinoma. Both NER activity and ERCC1 expression were increased after exposure to the epidermal growth factor (EGF) in cultured normal and tumoral human hepatocytes. These increases correlated with the activation of the kinase signaling pathway mitogen-activated protein/extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK that is known to be a key regulator in the G(1) phase of the hepatocyte cell cycle. Moreover, EGF-mediated activation of ERCC1 was specifically inhibited by either the addition of U0126, a MEK/ERK inhibitor or small interfering RNA-mediated knockdown of ERK2. Basal expression of ERCC1 was decreased in the presence of the phosphoinositide-3-kinase (PI3K) inhibitor and small hairpin RNA (shRNA) against the PI3K pathway kinase FKBP12-rapamycin-associated protein or mammalian target of rapamycin. Transient transfection of human hepatocytes with constructs containing different sizes of the 5'-flanking region of the ERCC1 gene upstream of the luciferase reporter gene showed an increase in luciferase activity in EGF-treated cells, which correlated with the presence of the nuclear transcription factor GATA-1 recognition sequence. The recruitment of GATA-1 was confirmed by chromatin immunoprecipitation assay. In conclusion, these results represent the first demonstration of an up-regulation of NER and ERCC1 in EGF-stimulated proliferating hepatocytes. The transcription factor GATA-1 plays an essential role in the induction of ERCC1 through the mitogen-activated protein kinase (MAPK) pathway, whereas the PI3K signaling pathway contributes to ERCC1 basal expression.
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Affiliation(s)
- Lise O Andrieux
- Institut National de la Santé et de la Recherche Médicale U620, Université de Rennes I, Hôpital Pontchaillou, IFR 140, 2 avenue du Pr Léon Bernard, 35043 Rennes Cedex, France
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137
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Gu TL, Mercher T, Tyner JW, Goss VL, Walters DK, Cornejo MG, Reeves C, Popova L, Lee K, Heinrich MC, Rush J, Daibata M, Miyoshi I, Gilliland DG, Druker BJ, Polakiewicz RD. A novel fusion of RBM6 to CSF1R in acute megakaryoblastic leukemia. Blood 2007; 110:323-33. [PMID: 17360941 PMCID: PMC1896120 DOI: 10.1182/blood-2006-10-052282] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Activated tyrosine kinases have been frequently implicated in the pathogenesis of cancer, including acute myeloid leukemia (AML), and are validated targets for therapeutic intervention with small-molecule kinase inhibitors. To identify novel activated tyrosine kinases in AML, we used a discovery platform consisting of immunoaffinity profiling coupled to mass spectrometry that identifies large numbers of tyrosine-phosphorylated proteins, including active kinases. This method revealed the presence of an activated colony-stimulating factor 1 receptor (CSF1R) kinase in the acute megakaryoblastic leukemia (AMKL) cell line MKPL-1. Further studies using siRNA and a small-molecule inhibitor showed that CSF1R is essential for the growth and survival of MKPL-1 cells. DNA sequence analysis of cDNA generated by 5'RACE from CSF1R coding sequences identified a novel fusion of the RNA binding motif 6 (RBM6) gene to CSF1R gene generated presumably by a t(3;5)(p21;q33) translocation. Expression of the RBM6-CSF1R fusion protein conferred interleukin-3 (IL-3)-independent growth in BaF3 cells, and induces a myeloid proliferative disease (MPD) with features of megakaryoblastic leukemia in a murine transplant model. These findings identify a novel potential therapeutic target in leukemogenesis, and demonstrate the utility of phosphoproteomic strategies for discovery of tyrosine kinase alleles.
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MESH Headings
- Animals
- Cell Line
- Cell Line, Tumor
- Cell Proliferation
- Cell Survival
- Chromosomes, Human, Pair 3
- Chromosomes, Human, Pair 5
- Humans
- Leukemia, Megakaryoblastic, Acute/etiology
- Leukemia, Megakaryoblastic, Acute/genetics
- Mice
- Neoplasm Transplantation
- Oncogene Proteins, Fusion/genetics
- Oncogene Proteins, Fusion/isolation & purification
- Oncogene Proteins, Fusion/physiology
- Protein-Tyrosine Kinases/isolation & purification
- RNA-Binding Proteins/genetics
- Receptor, Macrophage Colony-Stimulating Factor/genetics
- Receptor, Macrophage Colony-Stimulating Factor/isolation & purification
- Sequence Analysis, DNA
- Translocation, Genetic
- Transplantation, Heterologous
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Affiliation(s)
- Ting-lei Gu
- Cell Signaling Technology, Danvers, MA 01923, USA
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138
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Martelli AM, Nyåkern M, Tabellini G, Bortul R, Tazzari PL, Evangelisti C, Cocco L. Phosphoinositide 3-kinase/Akt signaling pathway and its therapeutical implications for human acute myeloid leukemia. Leukemia 2006; 20:911-28. [PMID: 16642045 DOI: 10.1038/sj.leu.2404245] [Citation(s) in RCA: 262] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The phosphoinositide 3-kinase (PI3K)/Akt signaling pathway is crucial to many aspects of cell growth, survival and apoptosis, and its constitutive activation has been implicated in the both the pathogenesis and the progression of a wide variety of neoplasias. Hence, this pathway is an attractive target for the development of novel anticancer strategies. Recent studies showed that PI3K/Akt signaling is frequently activated in acute myeloid leukemia (AML) patient blasts and strongly contributes to proliferation, survival and drug resistance of these cells. Upregulation of the PI3K/Akt network in AML may be due to several reasons, including FLT3, Ras or c-Kit mutations. Small molecules designed to selectively target key components of this signal transduction cascade induce apoptosis and/or markedly increase conventional drug sensitivity of AML blasts in vitro. Thus, inhibitory molecules are currently being developed for clinical use either as single agents or in combination with conventional therapies. However, the PI3K/Akt pathway is important for many physiological cellular functions and, in particular, for insulin signaling, so that its blockade in vivo might cause severe systemic side effects. In this review, we summarize the existing knowledge about PI3K/Akt signaling in AML cells and we examine the rationale for targeting this fundamental signal transduction network by means of selective pharmacological inhibitors.
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Affiliation(s)
- A M Martelli
- Cell Signalling Laboratory, Dipartimento di Scienze Anatomiche Umane e Fisiopatologia dell'Apparato Locomotore, Sezione di Anatomia Umana, Università di Bologna, Bologna, Italy.
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139
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Komatsu N. [Fundamentals of erythropoiesis. 2, Erythropoietin and the control of erythropoiesis]. NIHON NAIKA GAKKAI ZASSHI. THE JOURNAL OF THE JAPANESE SOCIETY OF INTERNAL MEDICINE 2006; 95:1988-93. [PMID: 17100252 DOI: 10.2169/naika.95.1988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
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140
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Rooke HM, Orkin SH. Phosphorylation of Gata1 at serine residues 72, 142, and 310 is not essential for hematopoiesis in vivo. Blood 2006; 107:3527-30. [PMID: 16391009 PMCID: PMC1895769 DOI: 10.1182/blood-2005-10-4309] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Phosphorylation of transcription factors is important in posttranslational control of protein function. The indispensable zinc-finger transcription factor, Gata1, is phosphorylated constitutively at 6 serine residues (26, 49, 72, 142, 178, 187), and at a seventh (310) following induction of erythroid differentiation. However, the biologic consequences of phosphorylation with respect to function are unclear. To address this issue, we generated mice with serine-to-alanine mutations at the inducibly phosphorylated serine 310 alone or at conserved serine residues 72, 142, and 310 together. The peripheral blood parameters of the mice were normal, as was their response to acute erythropoietic stress. Analysis of hematopoietic progenitor populations during ontogeny and into adulthood showed a moderate decrease in erythroid burst-forming unit (BFU-E) and erythroid colony-forming unit (CFU-E) numbers only in the adult bone marrow of the triple mutant. Yet, later stage erythropoiesis was not perturbed. This suggests that any molecular consequences associated with loss of phosphorylation at residues 72, 142, and 310 can be compensated for in the in vivo environment.
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Affiliation(s)
- Heather M Rooke
- Division of Hematology/Oncology, Children's Hospital, 300 Longwood Ave, Boston, MA 02115, USA
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141
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Ghaffari S, Kitidis C, Zhao W, Marinkovic D, Fleming MD, Luo B, Marszalek J, Lodish HF. AKT induces erythroid-cell maturation of JAK2-deficient fetal liver progenitor cells and is required for Epo regulation of erythroid-cell differentiation. Blood 2005; 107:1888-91. [PMID: 16254141 PMCID: PMC1895702 DOI: 10.1182/blood-2005-06-2304] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AKT serine threonine kinase of the protein kinase B (PKB) family plays essential roles in cell survival, growth, metabolism, and differentiation. In the erythroid system, AKT is known to be rapidly phosphorylated and activated in response to erythropoietin (Epo) engagement of Epo receptor (EpoR) and to sustain survival signals in cultured erythroid cells. Here we demonstrate that activated AKT complements EpoR signaling and supports erythroid-cell differentiation in wild-type and JAK2-deficient fetal liver cells. We show that erythroid maturation of AKT-transduced cells is not solely dependent on AKT-induced cell survival or proliferation signals, suggesting that AKT transduces also a differentiation-specific signal downstream of EpoR in erythroid cells. Down-regulation of expression of AKT kinase by RNA interference, or AKT activity by expression of dominant negative forms, inhibits significantly fetal liver-derived erythroid-cell colony formation and gene expression, demonstrating that AKT is required for Epo regulation of erythroid-cell maturation.
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Affiliation(s)
- Saghi Ghaffari
- Department of Gene and Cell Medicine, Mount Sinai School of Medicine, New York, NY 10029, USA.
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