Polymeric Immunoglobulin A1 Controls Erythroblast Proliferation and Accelerates Erythropoiesis Recovery in Anemia

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 679-679
Author(s):  
Séverine Coulon ◽  
Michael Dussiot ◽  
Damien Grapton ◽  
Thiago Maciel ◽  
Pamella Huey Mei Wang ◽  
...  
Keyword(s):  
Cell Activation ◽  
Conflicts Of Interest ◽  
Iga Deficiency ◽  
Mitogen Activated Protein Kinase ◽  
Erythroid Progenitors ◽  
Humanized Mouse Model ◽  
Stress Erythropoiesis ◽  
J Chain ◽  
Mitogen Activated Protein ◽  
Clonogenic Potential

Abstract Abstract 679 Erythropoietin (Epo) is the main cytokine controlling terminal erythropoiesis. Twenty years ago a model of erythropoiesis regulation has been described suggesting that the circulating Epo level is suboptimal and only a fraction of erythroid progenitors survives to produce erythrocytes (Koury and Bondurant; Science, 1990). Therefore differential Epo sensitivity would control erythroblasts survival. However, cell autonomous and/or environmental factors controlling this process remain elusive. Erythroblasts highly express the transferrin receptor 1 (TfR1), which has been shown to be essential for iron uptake allowing hemoglobin synthesis. We have previously identified TfR1 as an unsuspected polymeric (p)IgA1 receptor. Here we show that TfR1-bound pIgA1 (but not monomeric (m)IgA1) rescued the growth and clonogenic potential of human erythroblasts under suboptimal Epo concentrations. In a humanized mouse model (α1KI mice) IgA1 polymers increased spleen homeostatic erythropoietic activity and accelerated stress erythropoiesis in several models of anemia (phenylhydrazine and autoimmune hemolytic anemia; 5-fluorouracyl-induced central anemia). By contrast, mice lacking the immunoglobulin joining-(J) chain (α1KI/J-chain−/−), which are devoid of pIgA1 demonstrated a delayed recovery from anemia. Moreover, IgA deficiency patients presented increased Epo levels. Upon hypoxia, pIgA1 levels increased in both humans and mice. Likewise, α1KI mice submitted to chronic intermittent hypoxia presented an enhanced erythroblasts expansion relative to their LT controls. Therefore, hypoxia regulates pIgA1 production and, in turn, pIgA1/TfR1 interaction modulates erythroblast sensitivity to growth factors by decreasing cell activation threshold. We also showed that the natural TfR1 ligand, iron-loaded transferrin (Fe-Tf), also accelerated recovery from acute anemia. At the molecular level, pIgA1 and Fe-Tf converged for Epo-dependent erythroblasts proliferation. TfR1 engagement increased cell sensitivity to Epo by inducing activation of mitogen-activated protein kinase and phosphatidylinositol-3-kinase signaling pathways. These cellular responses were mediated by the TfR1-internalization motif, YXXΦ. Therefore, pIgA1 and TfR1 are positive regulators of erythropoiesis in both physiological and pathological situations. This study shed light on a new role of TfR1 as a signaling competent receptor. Targeting this pathway could provide alternative approaches to treat anemia, in particular in Epo hypo-responsive patients and dyserythropoiesis. Disclosures: No relevant conflicts of interest to declare.

Tyrosine kinase receptor RON functions downstream of the erythropoietin receptor to induce expansion of erythroid progenitors

Blood ◽  
2004 ◽  
Vol 103 (12) ◽  
pp. 4457-4465 ◽  
Author(s):  
Emile van den Akker ◽  
Thamar van Dijk ◽  
Martine Parren-van Amelsvoort ◽  
Katja S. Grossmann ◽  
Ute Schaeper ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Erythropoietin Receptor ◽  
Mitogen Activated Protein Kinase ◽  
Tyrosine Kinase Receptor ◽  
Erythroid Progenitors ◽  
Downstream Target ◽  
Stress Erythropoiesis ◽  
Mitogen Activated Protein ◽  
Induced Signal

Abstract Erythropoietin (EPO) is required for cell survival during differentiation and for progenitor expansion during stress erythropoiesis. Although signaling pathways may couple directly to docking sites on the EPO receptor (EpoR), additional docking molecules expand the signaling platform of the receptor. We studied the roles of the docking molecules Grb2-associated binder-1 (Gab1) and Gab2 in EPO-induced signal transduction and erythropoiesis. Inhibitors of phosphatidylinositide 3-kinase and Src kinases suppressed EPO-dependent phosphorylation of Gab2. In contrast, Gab1 activation depends on recruitment and phosphorylation by the tyrosine kinase receptor RON, with which it is constitutively associated. RON activation induces the phosphorylation of Gab1, mitogen-activated protein kinase (MAPK), and protein kinase B (PKB) but not of signal transducer and activator of transcription 5 (Stat5). RON activation was sufficient to replace EPO in progenitor expansion but not in differentiation. In conclusion, we elucidated a novel mechanism specifically involved in the expansion of erythroblasts involving RON as a downstream target of the EpoR. (Blood. 2004;103:4457-4465)

The inositol phosphatase SHIP-1 is negatively regulated by Fli-1 and its loss accelerates leukemogenesis

Blood ◽  
2010 ◽  
Vol 116 (3) ◽  
pp. 428-436 ◽  
Author(s):  
Gurpreet K. Lakhanpal ◽  
Laura M. Vecchiarelli-Federico ◽  
You-Jun Li ◽  
Jiu-Wei Cui ◽  
Monica L. Bailey ◽  
...  
Keyword(s):  
Leukemia Virus ◽  
Signal Transduction Pathway ◽  
Erythroid Differentiation ◽  
Sh2 Domain ◽  
Mitogen Activated Protein Kinase ◽  
Erythroid Progenitors ◽  
Genetic Event ◽  
Ras Pathway ◽  
Inositol Phosphatase ◽  
Mitogen Activated Protein

Abstract The activation of Fli-1, an Ets transcription factor, is the critical genetic event in Friend murine leukemia virus (F-MuLV)–induced erythroleukemia. Fli-1 overexpression leads to erythropoietin-dependent erythroblast proliferation, enhanced survival, and inhibition of terminal differentiation, through activation of the Ras pathway. However, the mechanism by which Fli-1 activates this signal transduction pathway has yet to be identified. Down-regulation of the Src homology 2 (SH2) domain-containing inositol-5-phosphatase-1 (SHIP-1) is associated with erythropoietin-stimulated erythroleukemic cells and correlates with increased proliferation of transformed cells. In this study, we have shown that F-MuLV–infected SHIP-1 knockout mice display accelerated erythroleukemia progression. In addition, RNA interference (RNAi)-mediated suppression of SHIP-1 in erythroleukemia cells activates the phosphatidylinositol 3-kinase (PI 3-K) and extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathways, blocks erythroid differentiation, accelerates erythropoietin-induced proliferation, and leads to PI 3-K–dependent Fli-1 up-regulation. Chromatin immunoprecipitation and luciferase assays confirmed that Fli-1 binds directly to an Ets DNA binding site within the SHIP-1 promoter and suppresses SHIP-1 transcription. These data provide evidence to suggest that SHIP-1 is a direct Fli-1 target, SHIP-1 and Fli-1 regulate each other in a negative feedback loop, and the suppression of SHIP-1 by Fli-1 plays an important role in the transformation of erythroid progenitors by F-MuLV.

scholarly journals Receptor Heterodimerization and Co-Receptor Engagement in TLR2 Activation Induced by MIC1 and MIC4 from Toxoplasma gondii

2019 ◽  
Vol 20 (20) ◽  
pp. 5001 ◽  
Author(s):  
Flávia Costa Mendonça-Natividade ◽  
Carla Duque Lopes ◽  
Rafael Ricci-Azevedo ◽  
Aline Sardinha-Silva ◽  
Camila Figueiredo Pinzan ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Transforming Growth Factor Beta ◽  
Cell Activation ◽  
Cytokine Production ◽  
Transforming Growth Factor ◽  
Protein Complexes ◽  
Transmembrane Protein ◽  
Mitogen Activated Protein Kinase ◽  
Mitogen Activated Protein ◽  
Carbohydrate Recognition Domains

The microneme organelles of Toxoplasma gondii tachyzoites release protein complexes (MICs), including one composed of the transmembrane protein MIC6 plus MIC1 and MIC4. In this complex, carbohydrate recognition domains of MIC1 and MIC4 are exposed and interact with terminal sialic acid and galactose residues, respectively, of host cell glycans. Recently, we demonstrated that MIC1 and MIC4 binding to the N-glycans of Toll-like receptor (TLR) 2 and TLR4 on phagocytes triggers cell activation and pro-inflammatory cytokine production. Herein, we investigated the requirement for TLR2 heterodimerization and co-receptors in MIC-induced responses, as well as the signaling molecules involved. We used MICs to stimulate macrophages and HEK293T cells transfected with TLR2 and TLR1 or TLR6, both with or without the co-receptors CD14 and CD36. Then, the cell responses were analyzed, including nuclear factor-kappa B (NF-κB) activation and cytokine production, which showed that (1) only TLR2, among the studied factors, is crucial for MIC-induced cell activation; (2) TLR2 heterodimerization augments, but is not critical for, activation; (3) CD14 and CD36 enhance the response to MIC stimulus; and (4) MICs activate cells through a transforming growth factor beta-activated kinase 1 (TAK1)-, mammalian p38 mitogen-activated protein kinase (p38)-, and NF-κB-dependent pathway. Remarkably, among the studied factors, the interaction of MIC1 and MIC4 with TLR2 N-glycans is sufficient to induce cell activation, which promotes host protection against T. gondii infection.

scholarly journals Deciphering the Contribution of Human Meningothelial Cells to the Inflammatory and Antimicrobial Response at the Meninges

2013 ◽  
Vol 81 (11) ◽  
pp. 4299-4310 ◽  
Author(s):  
Pierre-Joseph Royer ◽  
Andrew J. Rogers ◽  
Karl G. Wooldridge ◽  
Patrick Tighe ◽  
Jafar Mahdavi ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Intracellular Signaling ◽  
Cell Activation ◽  
Mitogen Activated Protein Kinase ◽  
Meningococcal Infection ◽  
Minor Role ◽  
Content Type ◽  
Wide Range ◽  
Mitogen Activated Protein ◽  
High Level

ABSTRACTWe have investigated the response of primary human meningothelial cells toNeisseria meningitidis. Through a transcriptome analysis, we provide a comprehensive examination of the response of meningothelial cells to bacterial infection. A wide range of chemokines are elicited which act to attract and activate the main players of innate and adaptive immunity. We showed that meningothelial cells expressed a high level of Toll-like receptor 4 (TLR4), and, using a gene silencing strategy, we demonstrated the contribution of this pathogen recognition receptor in meningothelial cell activation. Secretion of interleukin-6 (IL-6), CXCL10, and CCL5 was almost exclusively TLR4 dependent and relied on MyD88 and TRIF adaptor cooperation. In contrast, IL-8 induction was independent of the presence of TLR4, MyD88, and TRIF. Transcription factors NF-κB p65, p38 mitogen-activated protein kinase (MAPK), Jun N-terminal protein kinase (JNK1), IRF3, and IRF7 were activated after contact with bacteria. Interestingly, the protein kinase IRAK4 was found to play a minor role in the meningothelial cell response toNeisseriainfection. Our work highlights the role of meningothelial cells in the development of an immune response and inflammation in the central nervous system (CNS) in response to meningococcal infection. It also sheds light on the complexity of intracellular signaling after TLR triggering.

scholarly journals Emerging EPO and EPO receptor regulators and signal transducers

Blood ◽  
2015 ◽  
Vol 125 (23) ◽  
pp. 3536-3541 ◽  
Author(s):  
David Kuhrt ◽  
Don M. Wojchowski
Keyword(s):  
Biological Effects ◽  
Hypoxia Inducible Factor ◽  
Janus Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Cell Surface Receptor ◽  
Erythroid Progenitors ◽  
Epo Receptor ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Surface Receptor

Abstract As essential mediators of red cell production, erythropoietin (EPO) and its cell surface receptor (EPO receptor [EPOR]) have been intensely studied. Early investigations defined basic mechanisms for hypoxia-inducible factor induction of EPO expression, and within erythroid progenitors EPOR engagement of canonical Janus kinase 2/signal transducer and activator of transcription 5 (JAK2/STAT5), rat sarcoma/mitogen-activated protein kinase/extracellular signal-regulated kinase (RAS/MEK/ERK), and phosphatidylinositol 3-kinase (PI3K) pathways. Contemporary genetic, bioinformatic, and proteomic approaches continue to uncover new clinically relevant modulators of EPO and EPOR expression, and EPO’s biological effects. This Spotlight review highlights such factors and their emerging roles during erythropoiesis and anemia.

scholarly journals Functional Requirements of a Samd14-Capping Protein Interaction in Stress Erythropoiesis

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 288-288
Author(s):  
Suhita Ray ◽  
Linda Chee ◽  
Nicholas T. Woods ◽  
Kyle J Hewitt
Keyword(s):  
Steady State ◽  
Hemolytic Anemia ◽  
Conflicts Of Interest ◽  
Ex Vivo ◽  
Interacting Proteins ◽  
Erythroid Progenitors ◽  
Erythroid Progenitor ◽  
Capping Protein ◽  
Sam Domain ◽  
Stress Erythropoiesis

Abstract Stress erythropoiesis describes the process of accelerating red blood cell (RBC) production in anemia. Among a number of important mediators of stress erythropoiesis, paracrine signals - involving cooperation between SCF/c-Kit signaling and other signaling inputs - are required for the activation/function of stress erythroid progenitors. Whereas many critical factors required to drive erythropoiesis in normal physiological conditions have been described, whether distinct mechanisms control developmental, steady-state, and stress erythropoiesis in anemia is poorly understood. Our prior work revealed that the Sterile Alpha Motif (SAM) Domain 14 (Samd14) gene is transcriptionally upregulated in a model of acute hemolytic anemia induced by the RBC-lysing chemical phenylhydrazine. Samd14 is regulated by GATA binding transcription factors via an intronic enhancer (Samd14-Enh). In a mouse knockout of Samd14-Enh (Samd14-Enh -/-), we established that the Samd14-Enh is dispensable for steady-state erythropoiesis but is required for recovery from severe hemolytic anemia. Samd14 promotes c-Kit signaling in vivo and ex vivo, and the SAM domain of Samd14 facilitates c-Kit-mediated cellular signaling and stress progenitor activity. In addition, the Samd14 SAM domain is functionally distinct from closely related SAM domains, which demonstrates a unique role for this SAM domain in stress signaling and cell survival. In our working model, Samd14-Enh is part of an ensemble of anemia-responsive enhancers which promote stress erythroid progenitor activity. However, the mechanism underlying Samd14's role in stress erythropoiesis is unknown. To identify potential Samd14-interacting proteins that mediate its function, we performed immunoprecipitation-mass spectrometry on the Samd14 protein. We found that Samd14 interacted with α- and β heterodimers of the F-actin capping protein (CP) complex independent of the SAM domain. CP binds to actin during filament assembly/disassembly and plays a role in cell morphology, migration, and signaling. Deleting a 17 amino acid sequence near the N-terminus of Samd14 disrupted the Samd14-CP interaction. However, mutating the canonical RxR of the CP interaction (CPI) motif, which is required for CP-binding in other proteins, does not abrogate the Samd14-CP interaction. Moreover, replacing this sequence with the canonical CPI domain of CKIP-1 completely disrupts the interaction, indicating that other sequence features are required to maintain the Samd14-CP complex. Ex vivo knockdown of the β-subunit of CP (CPβ), which disrupts the integrity of the CP complex, decreased the percentage of early erythroid precursors (p<0.0001) and decreased (3-fold) progenitor activity as measured by colony formation assays (similar to knockdown of Samd14). Taken together, these data indicate that Samd14 interacts with CP via a unique CP binding (CPB) domain, and that the CP complex coordinates erythroid differentiation in stress erythroid progenitors. To test the function of the Samd14-CP complex, we designed an ex vivo genetic complementation assay to express Samd14 lacking the CPB-domain (Samd14∆CPB) in stress erythroid progenitors isolated from anemic Samd14-Enh -/- mice. Phospho-AKT (Ser473) and phospho-ERK (Thr202/Tyr204) levels in Samd14∆CPB were, respectively, 2.2 fold (p=0.007) and ~7 fold (n=3) lower than wild type Samd14 expressing cells, 5 min post SCF stimulation. Relative to Samd14, Samd14∆CPB expression reduced burst forming unit-erythroid (BFU-E) (2.0 fold) and colony forming unit-erythroid (CFU-E) (1.5 fold). These results revealed that the Samd14-CP interaction is a determinant of BFU-E and CFU-E progenitor cell levels and function. Remarkably, as the requirement of the CPB domain in BFU-E and CFU-E progenitors is distinct from the Samd14-SAM domain (which promotes BFU-E but not CFU-E), the function of Samd14 in these two cell types may differ. Ongoing studies will examine whether the function of Samd14 extends beyond SCF/c-Kit signaling and establish cell type-dependent functions of Samd14 and Samd14-interacting proteins. Given the critical importance of c-Kit signaling in hematopoiesis, the role of Samd14 in mediating pathway activation, and our discovery implicating the capping protein complex in erythropoiesis, it is worth considering the pathological implications of this mechanism in acute/chronic anemia and leukemia. Disclosures No relevant conflicts of interest to declare.

IL-35 Suppresses Lipopolysaccharide-Induced Endothelial Cell Activation Through Downregulation of MAPK Signaling-Mediated Upregulation of Adhesion Molecule VCAM-1

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3310-3310
Author(s):  
Xiaojin Sha ◽  
Shu Meng ◽  
Xinyuan Li ◽  
Jahaira Lopez Pastrana ◽  
Hong Wang ◽  
...  
Keyword(s):  
Endothelial Cell ◽  
Adhesion Molecule ◽  
Cell Activation ◽  
Conflicts Of Interest ◽  
Vascular Inflammation ◽  
Endothelial Activation ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Interleukin 12 ◽  
Endothelial Cell Activation

Abstract Abstract 3310 Our previous reports showed that survival/apoptosis of CD4+CD25+Foxp3+ regulatory T cells (Tregs) modulates vascular inflammation even though the mode of Tregs inhibition was unknown. Interleukin-35 (IL-35), consisting of two subunits Epstein-Barr virus–induced gene 3 (EBI3) and p35, is a novel anti-inflammatory cytokine, which is a member of the interleukin-12 (IL-12) cytokine family. IL-35 is produced by Tregs. It has been shown that IL-35 suppresses chronic inflammatory diseases such as asthma and inflammatory bowel diseases. However, an important question of whether IL-35 can carry out Tregs suppression and inhibit endothelial cell (EC) activation in acute inflammation remained unknown. Here we found that IL-35 significantly inhibits lung neutrophil infiltration into the surrounding areas of bronchioles and alveolar space when induced by intraperitoneal injection of lipopolysaccharide (LPS) in wild type mice and EBI3-deficient mice. Furthermore, cremaster microvasculature study using intravital microscopy showed IL-35 significantly suppresses leukocyte adhesion to the vascular wall as well, suggesting IL-35 inhibition of endothelial activation. Mechanistically, IL-35 inhibited LPS-induced upregulation of adhesion molecules on human aortic endothelial cells, a marker of endothelial activation, including vascular cell adhesion molecule 1 (VCAM-1). IL-35 acted through new IL-35 dimeric receptors gp130 and IL-12Rβ2, and inhibited VCAM-1 promoter transcription in mitogen-activated protein kinase (MAPK)-mediated pathway. These results provide a novel insight on Tregs and IL-35 inhibition of vascular inflammation. Disclosures: No relevant conflicts of interest to declare.

Phosphatase inhibition promotes antiapoptotic but not proliferative signaling pathways in erythropoietin-dependent HCD57 cells

Blood ◽  
2000 ◽  
Vol 96 (6) ◽  
pp. 2084-2092
Author(s):  
Amy E. Lawson ◽  
Haifeng Bao ◽  
Amittha Wickrema ◽  
Sarah M. Jacobs-Helber ◽  
Stephen T. Sawyer
Keyword(s):  
Tyrosine Phosphatase ◽  
Critical Role ◽  
Mitogen Activated Protein Kinase ◽  
Phosphatidylinositol 3 Kinase ◽  
Erythroid Progenitors ◽  
Murine Cell Line ◽  
Mitogen Activated Protein ◽  
Erk Activity ◽  
Kinase Pathway

Erythropoietin (EPO) allows erythroid precursors to proliferate while protecting them from apoptosis. Treatment of the EPO-dependent HCD57 murine cell line with 70 μmol/L orthovanadate, a tyrosine phosphatase inhibitor, resulted in both increased tyrosine protein phosphorylation and prevention of apoptosis in the absence of EPO without promoting proliferation. Orthovanadate also delayed apoptosis in primary human erythroid progenitors. Thus, we investigated what survival signals were activated by orthovanadate treatment. Expression of Bcl-XL and BAD phosphorylation are critical for the survival of erythroid cells, and orthovanadate in the absence of EPO both maintained expression levels of antiapoptotic Bcl-XLand induced BAD phosphorylation at serine 112. Orthovanadate activated JAK2, STAT1, STAT5, the phosphatidylinositol-3 kinase (PI-3 kinase) pathway, and other signals such as JNK and p38 without activating the EPO receptor, JAK1, Tyk2, Vav, STAT3, and SHC. Neither JNK nor p38 appeared to have a central role in either apoptosis or survival induced by orthovanadate. Treatment with cells with LY294002, an inhibitor of PI-3 kinase activity, triggered apoptosis in orthovanadate-treated cells, suggesting a critical role of PI-3 kinase in orthovanadate-stimulated survival. Mitogen-activated protein kinase (MAPK) was poorly activated by orthovanadate, and inhibition of MAPK with PD98059 blocked proliferation without inducing apoptosis. Thus, orthovanadate likely acts to greatly increase JAK/STAT and PI-3 kinase basal activity in untreated cells by blocking tyrosine protein phosphatase activity. Activated JAK2/STAT5 then likely acts upstream of Bcl-XL expression and PI-3 kinase likely promotes BAD phosphorylation to protect from apoptosis. In contrast, MAPK/ERK activity correlates with only EPO-dependent proliferation but is not required for survival of HCD57 cells.

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