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Clark-Corrigall J, Myssina S, Michaelis M, Cinatl J, Ahmed S, Carr-Wilkinson J, Carr-Wilkinson J. Elevated Expression of LGR5 and WNT Signaling Factors in Neuroblastoma Cells With Acquired Drug Resistance. Cancer Invest 2023; 41:173-182. [PMID: 36318235 DOI: 10.1080/07357907.2022.2136682] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Neuroblastoma (NB) is a pediatric solid cancer with high fatality, relapses, and acquired resistance to chemotherapy, that requires new therapeutic approaches to improve survival. LGR5 is a receptor that potentiates WNT/signaling pathway and has been reported to promote development and survival in several adult cancers. In this study we investigated LGR5 expression in a panel of NB cell lines with acquired resistance to vincristine or doxorubicin. We show LGR5-LRP6 cooperation with enhanced expression in drug resistant NB cell lines compared to parental cells, suggesting a role for LGR5 in the emergence of drug resistance, warranting further investigation.
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Affiliation(s)
- John Clark-Corrigall
- School of Nursing and Health Sciences, Faculty of Health Sciences and Wellbeing, University of Sunderland, Sunderland, UK
| | - Svetlana Myssina
- School of Nursing and Health Sciences, Faculty of Health Sciences and Wellbeing, University of Sunderland, Sunderland, UK
| | - Martin Michaelis
- School of Biosciences and Industrial Biotechnology Centre, University of Kent, Canterbury, UK
| | - Jindrich Cinatl
- Institut für Medizinische Virologie, Klinikum der Goethe-Universität, Frankfurt am Main, Germany
| | - Shafiq Ahmed
- School of Medicine, Faculty of Health Sciences and Wellbeing, University of Sunderland, Sunderland, UK
| | - Jane Carr-Wilkinson
- School of Medicine, Faculty of Health Sciences and Wellbeing, University of Sunderland, Sunderland, UK
| | - Jane Carr-Wilkinson
- School of Medicine, Faculty of Health Sciences and Wellbeing, University of Sunderland, United Kingdom
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Hamilton A, Alhashimi F, Myssina S, Jorgensen HG, Holyoake TL. Optimization of methods for the detection of BCR-ABL activity in Philadelphia-positive cells. Exp Hematol 2009; 37:395-401. [DOI: 10.1016/j.exphem.2008.11.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 11/05/2008] [Accepted: 11/10/2008] [Indexed: 10/21/2022]
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Myssina S, Helgason GV, Serrels A, Jørgensen HG, Bhatia R, Modi H, Baird JW, Mountford JC, Hamilton A, Schemionek M, Koschmieder S, Brunton VG, Holyoake TL. Combined BCR-ABL inhibition with lentiviral-delivered shRNA and dasatinib augments induction of apoptosis in Philadelphia-positive cells. Exp Hematol 2008; 37:206-14. [PMID: 19100678 DOI: 10.1016/j.exphem.2008.10.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Revised: 10/21/2008] [Accepted: 10/22/2008] [Indexed: 11/29/2022]
Abstract
OBJECTIVE This study investigated two approaches, short hairpin RNA (shRNA) and the potent ABL inhibitor, dasatinib, alone and together, to achieve complete inhibition of BCR-ABL activity in Philadelphia-positive (Ph(+)) cells. MATERIALS AND METHODS shRNA specific for BCR-ABL b3a2 were delivered, by lentiviral transduction or electroporation, to K562 cells, with or without dasatinib. mRNA and protein knockdown were measured by quantitative reverse transcriptase polymerase chain reaction, flow cytometry, and Western blotting. BCR-ABL activity was assessed by intracellular flow cytometry for pCrkL. Cell death and apoptosis were assayed using trypan blue exclusion, Annexin-V, and active caspase-3 staining. RESULTS Forty-eight hours after transduction or electroporation of shRNA, BCR-ABL mRNA, and protein were reduced by 75% and >90%, respectively, and sustained for 5 days. Lentiviral delivery and electroporation were equally effective. pCrkL was inhibited in association with cell death. By 5 days after transduction or electroporation, viable cells represented 50% of input, with a 12-fold reduction vs control, which expanded 6-fold. When shRNA, titrated by green fluorescent protein into low and high, was combined with dasatinib (concentration range, 0-10 nM), low shRNA was additive with low dasatinib (0.6 and 1 nM), leading to inhibition of pCrkL, induction of activated caspase-3, expression of Annexin-V, and marked reduction in viable cells. CONCLUSION These results confirm that by lowering BCR-ABL levels with shRNA, complete inhibition of oncoprotein activity can be achieved with a lower concentration of dasatinib, thus providing a rationale for combining these approaches in the setting of high target expression, such as found in advanced phase disease and in the stem cell compartment.
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Affiliation(s)
- Svetlana Myssina
- Section of Experimental Haematology, Division of Cancer Sciences and Molecular Pathology, Faculty of Medicine, University of Glasgow, Glasgow, UK
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Hamilton A, Elrick L, Myssina S, Copland M, Jørgensen H, Melo JV, Holyoake T. BCR-ABL activity and its response to drugs can be determined in CD34+ CML stem cells by CrkL phosphorylation status using flow cytometry. Leukemia 2006; 20:1035-9. [PMID: 16572205 DOI: 10.1038/sj.leu.2404189] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In chronic myeloid leukaemia, CD34(+) stem/progenitor cells appear resistant to imatinib mesylate (IM) in vitro and in vivo. To investigate the underlying mechanism(s) of IM resistance, it is essential to quantify Bcr-Abl kinase status at the stem cell level. We developed a flow cytometry method to measure CrkL phosphorylation (P-CrkL) in samples with <10(4) cells. The method was first validated in wild-type (K562) and mutant (BAF3) BCR-ABL(+) as well as BCR-ABL(-) (HL60) cell lines. In response to increasing IM concentration, there was a linear reduction in P-CrkL, which was Bcr-Abl specific and correlated with known resistance. The results were comparable to those from Western blotting. The method also proved to be reproducible with small samples of normal and Ph(+) CD34(+) cells and was able to discriminate between Ph(-), sensitive and resistant Ph(+) cells. This assay should now enable investigators to unravel the mechanism(s) of IM resistance in stem cells.
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MESH Headings
- Adaptor Proteins, Signal Transducing/metabolism
- Antigens, CD34/biosynthesis
- Benzamides
- Cell Line, Tumor
- Dose-Response Relationship, Drug
- Drug Resistance, Neoplasm
- Flow Cytometry/methods
- Fusion Proteins, bcr-abl/drug effects
- Fusion Proteins, bcr-abl/genetics
- Fusion Proteins, bcr-abl/metabolism
- HL-60 Cells
- Hematopoietic Stem Cells/metabolism
- Humans
- Imatinib Mesylate
- In Vitro Techniques
- K562 Cells
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism
- Nuclear Proteins/metabolism
- Phosphorylation
- Piperazines/pharmacology
- Pyrimidines/pharmacology
- Sensitivity and Specificity
- Tumor Cells, Cultured
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Affiliation(s)
- A Hamilton
- Section of Experimental Haematology, Division of Cancer Sciences & Molecular Pathology, University of Glasgow, Glasgow, UK
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Lang PA, Kempe DS, Myssina S, Tanneur V, Birka C, Laufer S, Lang F, Wieder T, Huber SM. PGE(2) in the regulation of programmed erythrocyte death. Cell Death Differ 2005; 12:415-28. [PMID: 15746942 DOI: 10.1038/sj.cdd.4401561] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Hyperosmotic shock, energy depletion, or removal of extracellular Cl(-) activates Ca(2+)-permeable cation channels in erythrocyte membranes. Subsequent Ca(2+) entry induces erythrocyte shrinkage and exposure of phosphatidylserine (PS) at the erythrocyte surface. PS-exposing cells are engulfed by macrophages. The present study explored the signalling involved. Hyperosmotic shock and Cl(-) removal triggered the release of prostaglandin E(2) (PGE(2)). In whole-cell recording, activation of the cation channels by Cl(-) removal was abolished by the cyclooxygenase inhibitor diclophenac. In FACS analysis, phospholipase-A(2) inhibitors quinacrine and palmitoyltrifluoromethyl-ketone, and cyclooxygenase inhibitors acetylsalicylic acid and diclophenac, blunted the increase of PS exposure following Cl(-) removal. PGE(2) (but not thromboxane) induced cation channel activation, increase in cytosolic Ca(2+) concentration, cell shrinkage, PS exposure, calpain activation, and ankyrin-R degradation. The latter was attenuated by calpain inhibitors-I/II, while PGE(2)-induced PS exposure was not. In conclusion, hyperosmotic shock or Cl(-) removal stimulates erythrocyte PS exposure through PGE(2) formation and subsequent activation of Ca(2+)-permeable cation channels.
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Affiliation(s)
- P A Lang
- Department of Physiology, University of Tübingen, Germany.
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Shumilina E, Lampert A, Lupescu A, Myssina S, Strutz-Seebohm N, Henke G, Grahammer F, Wulff P, Kuhl D, Lang F. Deranged Kv channel regulation in fibroblasts from mice lacking the serum and glucocorticoid inducible kinase SGK1. J Cell Physiol 2005; 204:87-98. [PMID: 15605386 DOI: 10.1002/jcp.20267] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Coexpression of the serum and glucocorticoid inducible kinase 1 (SGK1) up-regulates Kv channel activity in Xenopus oocytes and human embryonic kidney cells. To investigate the physiological impact of SGK1 dependent Kv channel regulation, we recorded whole-cell currents in lung fibroblasts from SGK1 knockout mice (sgk1-/-) and wild-type littermates (sgk1+/+). Serum-grown mouse lung fibroblasts (MLF) from both genotypes exhibited voltage-gated outwardly rectifying K(+)-currents with time-dependent activation (tau(act) approximately 3 msec), slow inactivation (tau(inact) approximately 700 msec), use-dependent inactivation, and (partial) inhibition by K(+) channel blockers TEA, 4-AP, and margatoxin. In serum grown MLF peak Kv current density at +100 mV was significantly lower in sgk1-/- (14 +/- 2 pA/pF, n = 13) than in sgk1+/+ (31 +/- 4 pA/pF, n = 16). PCR amplification of different Kv1 and Kv3 subunits from mouse fibroblasts demonstrated the expression of Kv1.1-1.7, Kv3.1, and Kv3.3 mRNA in both sgk1+/+ and sgk1-/- cells. Upon serum deprivation Kv currents almost disappeared in sgk1+/+ (4 +/- 1 pA/pF, n = 11) but not in sgk1-/- (10 +/- 1 pA/pF, n = 6) MLF. Accordingly, following serum deprivation Kv current density was significantly lower in sgk1+/+ than in sgk1-/-. Stimulation of serum-depleted cells with dexamethasone (dex) (1 microM, 1 day), IGF-1 (6.7 microM, 4-6 h) or both, significantly activated Kv currents in sgk1+/+ but not in sgk1-/- MLF. In the presence of both, dex and IGF-1, the Kv current density was significantly larger in sgk1+/+ (27 +/- 3 pA/pF, n = 12) than in sgk1-/- (13 +/- 3 pA/pF, n = 10) cells. Similar to MLF, Kv currents were significantly higher in sgk1+/+ mouse tail fibroblasts (MTF). In sgk1+/+ but not sgk1-/- MTF the Kv currents were inhibited upon serum deprivation and reincreased after stimulation of serum deprived MTF with dex (1 microM, 1 day) and afterwards with IGF-1 (6.7 microM, 4-6 h). According to Fura-2-fluorescence capacitative Ca(2+) entry was lower in sgk1-/- MTF compared to sgk1+/+ MTF. Upon serum deprivation capacitative Ca(2+) entry decreased significantly in sgk1+/+ but not in sgk1-/- MTF. Stimulation of depleted cells with dex (1 microM, 1 day) and afterwards with IGF-1 (6.7 microM, 4-6 h) reincreased capacitative Ca(2+) entry in sgk1+/+ MTF, whereas in sgk1-/- cells it remained unchanged. In conclusion, lack of SGK1 does not abrogate Kv channel activity but abolishes regulation of those channels by serum, glucocorticoids and IGF-1, an effect influencing capacitative Ca(2+) entry.
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Lang PA, Kempe DS, Tanneur V, Eisele K, Klarl BA, Myssina S, Jendrossek V, Ishii S, Shimizu T, Waidmann M, Hessler G, Huber SM, Lang F, Wieder T. Stimulation of erythrocyte ceramide formation by platelet-activating factor. J Cell Sci 2005; 118:1233-43. [PMID: 15741229 DOI: 10.1242/jcs.01730] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Osmotic erythrocyte shrinkage leads to activation of cation channels with subsequent Ca2+ entry and stimulates a sphingomyelinase with subsequent formation of ceramide. Ca2+ and ceramide then activate a scramblase leading to breakdown of phosphatidylserine asymmetry of the cell membrane. The mediators accounting for activation of erythrocyte sphingomyelinase and phosphatidylserine exposure remained elusive. The study demonstrates that platelet-activating factor (PAF) is released from erythrocytes upon hyperosmotic cell shrinkage. The experiments further disclose the presence of PAF receptors in erythrocytes and show that PAF stimulates the breakdown of sphingomyelin and the release of ceramide from erythrocytes at isotonic conditions. PAF further triggers cell shrinkage (decrease of forward scatter) and phosphatidylserine exposure (annexin binding) of erythrocytes. The stimulation of annexin-binding is blunted by a genetic knockout of PAF receptors, by the PAF receptor antagonist ABT491 or by inhibition of sphingomyelinase with urea. In conclusion, PAF activates an erythrocyte sphingomyelinase and the then formed ceramide leads to the activation of scramblase with subsequent phosphatidylserine exposure.
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Affiliation(s)
- Philipp A Lang
- Department of Physiology, University of Tübingen, Germany
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Myssina S, Lang PA, Kempe DS, Kaiser S, Huber SM, Wieder T, Lang F. Cl- channel blockers NPPB and niflumic acid blunt Ca(2+)-induced erythrocyte 'apoptosis'. Cell Physiol Biochem 2005; 14:241-8. [PMID: 15319527 DOI: 10.1159/000080333] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/21/2004] [Indexed: 11/19/2022] Open
Abstract
Exposure to Ca2+ ionophore ionomycin, osmotic shock, oxidative stress and glucose depletion trigger cell shrinkage and scramblase-mediated phosphatidylserine exposure at the outer leaflet of the erythrocyte cell membrane. The effects are partially due to activation of GARDOS channels and subsequent cellular K+ loss leading not only to cell shrinkage but also participating in the triggering of erythrocyte scramblase. As conductive loss of K+ would depend on the parallel loss of anions we hypothesised that activation of scramblase is similarly dependent on the activity of Cl- channels. To test this hypothesis, we used Cl- channel blockers NPPB and niflumic acid. It is shown here that treatment of erythrocytes with 1 microM ionomycin leads to cellular K+ loss, decrease of hematocrit and decrease of forward scatter in FACS analysis reflecting cell shrinkage as well as increase of annexin positive cells reflecting phosphatidylserine exposure. Those events were significantly blunted in the presence of 100 microM NPPB by 34% (K+ loss), 45% (hematocrit), 32% (forward scatter) and 69% (annexin binding), or in the presence of 100 microM niflumic acid by 15% (forward scatter) and 45% (annexin binding), respectively. Moreover, oxidative stress triggered annexin binding which was again significantly inhibited (by 51%) in the presence of 100 microM NPPB. In conclusion, Cl- channels presumably participate in the regulation of erythrocyte 'apoptosis'.
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Baltaev R, Strutz-Seebohm N, Korniychuk G, Myssina S, Lang F, Seebohm G. Regulation of cardiac shal-related potassium channel Kv 4.3 by serum- and glucocorticoid-inducible kinase isoforms in Xenopus oocytes. Pflugers Arch 2004; 450:26-33. [PMID: 15578212 DOI: 10.1007/s00424-004-1369-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Accepted: 10/27/2004] [Indexed: 12/28/2022]
Abstract
The human cardiac transient outward potassium current I(to) is formed by co-assembly of voltage-dependent K(+) channel (Kv 4.3) pore-forming alpha-subunits with differently spliced K channel interacting protein (KChIP) accessory proteins. I(to) is of considerable importance for the normal course of the cardiac ventricular action potential. The present study was performed to determine whether isoforms of the serum- and glucocorticoid-inducible kinase (SGK) family influence Kv 4.3/KChIP2b channel activity in the Xenopus laevis heterologous expression system. Co-expression of SGK1, but not of SGK2 or SGK3, increased Kv 4.3/KChIP2b channel currents. The up-regulation of the current was not due to changes in the activation curve or changes of channel inactivation. The currents in oocytes expressing Kv 4.3 alone were smaller than those in Kv 4.3/KChIP2b expressing oocytes, but were still stimulated by SGK1. The effect of wild-type SGK1 was mimicked by constitutively active SGK1 (SGK1 S422D) but not by an inactive mutant (SGK1 K127N). The current amplitude increase mediated by SGK1 was not dependent on NEDD4.2 or RAB5, nor did it reflect increased cell surface expression. In conclusion, SGK1 stimulates Kv 4.3 potassium channels expressed in Xenopus oocytes by a novel mechanism distinct from the known NEDD4.2-dependent pathway.
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Affiliation(s)
- Ravshan Baltaev
- Department of Physiology I, University of Tübingen, Tübingen, Germany
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Lang KS, Myssina S, Brand V, Sandu C, Lang PA, Berchtold S, Huber SM, Lang F, Wieder T. Involvement of ceramide in hyperosmotic shock-induced death of erythrocytes. Cell Death Differ 2004; 11:231-43. [PMID: 14615798 DOI: 10.1038/sj.cdd.4401311] [Citation(s) in RCA: 168] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Erythrocytes lack nuclei and mitochondria, the organelles important for apoptosis of nucleated cells. However, following increase of cytosolic Ca(2+) activity, erythrocytes undergo cell shrinkage, cell membrane blebbing and breakdown of phosphatidylserine asymmetry, all features typical for apoptosis in nucleated cells. The same events are observed following osmotic shock, an effect mediated in part by activation of Ca(2+)-permeable cation channels. However, erythrocyte death following osmotic shock is blunted but not prevented in the absence of extracellular Ca(2+) pointing to additional mechanisms. As shown in this study, osmotic shock (950 mOsm) triggers sphingomyelin breakdown and formation of ceramide. The stimulation of annexin binding following osmotic shock is mimicked by addition of ceramide or purified sphingomyelinase and significantly blunted by genetic (aSM-deficient mice) or pharmacologic (50 microM 3,4-dichloroisocoumarin) knockout of sphingomyelinase. The effect of ceramide is blunted but not abolished in the absence of Ca(2+). Conversely, osmotic shock-induced annexin binding is potentiated in the presence of sublethal concentrations of ceramide. In conclusion, ceramide and Ca(2+) entry through cation channels concert to trigger erythrocyte death during osmotic shock.
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Affiliation(s)
- K S Lang
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076 Tübingen, Germany
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Birka C, Lang PA, Kempe DS, Hoefling L, Tanneur V, Duranton C, Nammi S, Henke G, Myssina S, Krikov M, Huber SM, Wieder T, Lang F. Enhanced susceptibility to erythrocyte "apoptosis" following phosphate depletion. Pflugers Arch 2004; 448:471-7. [PMID: 15156318 DOI: 10.1007/s00424-004-1289-y] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2003] [Accepted: 04/01/2004] [Indexed: 01/08/2023]
Abstract
Among the sequelae of phosphate depletion is anaemia, due in part to a decreased life span of mature erythrocytes. Recent studies have disclosed that cellular stress leads to an increase of cytosolic Ca(2+) activity in erythrocytes thereby triggering cell shrinkage and breakdown of phosphatidylserine asymmetry of the cell membrane, both typical features of apoptosis. In the present experiments, phosphatidylserine exposure and cell size were measured by fluorescence-activated cell sorting (FACS) analysis of annexin binding and forward scatter, respectively. Erythrocytes from intact mice were compared with erythrocytes from mice exposed to a low-phosphate diet for 4 days. Annexin binding of freshly drawn erythrocytes was slightly but significantly enhanced by the low-phosphate diet. Furthermore, intracellular phosphate and ATP concentrations were significantly decreased in those erythrocytes whereas intracellular Ca(2+) activity was unaltered. Osmotic shock (exposure to 700 mOsm by addition of sucrose for 12 h), removal of Cl(-) (replaced by gluconate for 15 h) or removal of glucose (12 h) decreased cell volume and increased the number of annexin-binding erythrocytes. Interestingly, these effects were significantly larger in erythrocytes from phosphate-depleted animals. The experiments reveal a novel mechanism triggered by phosphate depletion that presumably contributes to the enhanced vulnerability and accelerated sequestration of erythrocytes and, thus, to anaemia.
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Affiliation(s)
- Christina Birka
- Physiologisches Institut der Universität Tübingen, Gmelinstrasse 5, 72076 Tübingen, Germany
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Myssina S, Huber SM, Birka C, Lang PA, Lang KS, Friedrich B, Risler T, Wieder T, Lang F. Inhibition of erythrocyte cation channels by erythropoietin. J Am Soc Nephrol 2004; 14:2750-7. [PMID: 14569084 DOI: 10.1097/01.asn.0000093253.42641.c1] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Recombinant human erythropoietin therapy is used to counteract anemia that is the result of renal insufficiency. It stimulates the formation of peripheral blood erythrocytes by inhibiting apoptosis of erythrocyte precursor cells. Mature erythrocytes have similarly been shown to undergo apoptosis. Hyperosmotic shock and Cl(-) removal activate a Ca(2+)-permeable, ethylisopropylamiloride-inhibitable cation channel. The subsequent increase of cytosolic Ca(2+) activates a scramblase that breaks down cell membrane phosphatidylserine asymmetry, leading to annexin binding. Studied was whether channel activity and erythrocyte cell death are regulated by erythropoietin. Scatchard plot analysis disclosed low-abundance, high-affinity binding of (125)I-erythropoietin to erythrocytes. Whole cell patch clamp experiments revealed significant inhibition of the ethylisopropylamiloride-sensitive current by 1 U/ml erythropoietin. Cl(-) removal triggered annexin binding, an effect abrogated by erythropoietin (1 U/ml) but not by GM-CSF (10 ng/ml). Osmotic shock (700 mOsm) stimulated annexin binding within 24 h in the majority of the erythrocytes, an effect blunted by erythropoietin (1 U/ml) but not by GM-CSF (10 ng/ml). In the nominal absence of Ca(2+), the effect of osmotic shock was blunted and the effect of erythropoietin abolished. In hemodialysis patients, intravenous administration of erythropoietin (50 IU/kg) within 4 h decreased the number of annexin binding circulating erythrocytes. Erythropoietin binds to erythrocytes and inhibits volume-sensitive erythrocyte cation channels and thus the breakdown of phosphatidylserine asymmetry after activation of this channel. The effect could prolong the erythrocyte lifespan and may contribute to the enhancement of the erythrocyte number during erythropoietin therapy in dialysis patients.
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Lang F, Birka C, Myssina S, Lang KS, Lang PA, Tanneur V, Duranton C, Wieder T, Huber SM. Erythrocyte ion channels in regulation of apoptosis. Adv Exp Med Biol 2004; 559:211-217. [PMID: 18727242 DOI: 10.1007/0-387-23752-6_20] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Erythrocytes lack mitochondria and nuclei, key organelles in the regulation of apoptosis. Until recently, erythrocytes were thus not considered subject to this type of cell death. However, exposure of erythrocytes to the Ca2+ ionophore ionomycin was shown to induce cell shrinkage, cell membrane blebbing and breakdown of phosphatidylserine asymmetry with subsequent phosphatidylserine exposure at the cell surface, all typical features of apoptosis. Further studies revealed the participation of ion channels in the regulation of erythrocyte "apoptosis." Osmotic shock, oxidative stress and energy depletion all activate a Ca2(+)-permeable non-selective cation channel in the erythrocyte cell membrane. The subsequent increase of Ca2+ concentration stimulates a scramblase leading to breakdown of cell membrane phosphatidylserine asymmetry and activates Ca2+ sensitive K+ (Gardos) channels leading to KCl loss and (further) cell shrinkage. Phosphatidylserine exposure and cell shrinkage are blunted in the nominal absence of extracellular Ca2+, in the presence of the cation channel inhibitors amiloride or ethylisopropylamiloride, at increased extracellular K+ or in the presence of the Gardos channel inhibitors clotrimazole or charybdotoxin. Thus, increase of cytosolic Ca2+ and cellular loss of K+ participate in the triggering of erythrocyte scramblase. Nevertheless, phosphatidylserine exposure is not completely abrogated in the nominal absence of Ca2+, pointing to additional Ca2(+)-independent pathways. One of those is activation of sphingomyelinase with subsequent formation of ceramide which in turn leads to stimulation of erythrocyte scramblase. The exposure of phosphatidylserine at the extracellular face of the cell membrane stimulates phagocytes to engulf the apoptotic erythrocytes. Thus, sustained activation of the cation channels eventually leads to clearance of affected erythrocytes from peripheral blood. Erythropoietin inhibits the non-selective cation channel and thus interferes with erythrocyte "apoptosis." Susceptibility to scramblase activation is enhanced in thalassemia, sickle cell disease and glucose-6-phosphate dehydrogenase deficiency. Infection with Plasmodium falciparum leads to activation of the cation channel eventually triggering erythrocyte "apoptosis."
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Affiliation(s)
- Florian Lang
- Department of Physiology,Eberhard-Karls-University of Tuebingen, Gmelinstrasse 5, D-72076 Tuebingen, Germany.
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Lang PA, Warskulat U, Heller-Stilb B, Huang DY, Grenz A, Myssina S, Duszenko M, Lang F, Häussinger D, Vallon V, Wieder T. Blunted Apoptosis of Erythrocytes from Taurine Transporter Deficient Mice. Cell Physiol Biochem 2003; 13:337-46. [PMID: 14631140 DOI: 10.1159/000075121] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2003] [Indexed: 11/19/2022] Open
Abstract
In nucleated cells cellular taurine is released prior to DNA fragmentation and the breakdown of phosphatidylserine asymmetry within the plasma membrane. Similar to what is seen in nucleated cells, phosphatidylserine asymmetry is also abolished in erythrocytes exposed to osmotic shock or oxidative stress. The present study has been performed to explore the sensitivity of erythrocytes from a taurine transporter knockout mouse (taut-/-) against osmotic shock and oxidative stress. Erythrocyte cell volume was estimated from forward scatter and breakdown of phosphatidylserine asymmetry was identified by determination of annexin binding using FACS analysis. Erythrocytes from taut-/- mice were compared to erythrocytes from wild type littermates (taut+/+). Plasma concentration and erythrocyte content of taurine was significantly lower in taut-/- than in taut+/+ mice, but the intraerythrocyte taurine concentration did not exceed the plasma concentration. Hyperosmotic shock (exposure to 700 mOsm) and oxidative stress (exposure to 0.1 mM tert-butyl-hydroperoxide) significantly decreased the cell volume and increased the number of annexin binding sites of erythrocytes from both, taut-/- and taut+/+ mice. However, decrease of cell volume and increase of annexin binding was significantly blunted in erythrocytes from taut-/- mice as compared to their taut+/+ littermates. Stimulation of erythropoiesis by prior hemorrhage did not abrogate the difference between taut+/+ and taut-/- erythrocytes. The present observations point to a decreased sensitivity of mature erythrocytes from taut-/- mice to osmotic shock and oxidative stress, rendering them more resistant to apoptosis.
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Affiliation(s)
- Philipp A Lang
- Department of Physiology, University of Tuebingen, Germany
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Lang F, Lang KS, Wieder T, Myssina S, Birka C, Lang PA, Kaiser S, Kempe D, Duranton C, Huber SM. Cation channels, cell volume and the death of an erythrocyte. Pflugers Arch 2003; 447:121-5. [PMID: 12905029 DOI: 10.1007/s00424-003-1150-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2003] [Accepted: 07/16/2003] [Indexed: 10/26/2022]
Abstract
Similar to a variety of nucleated cells, human erythrocytes activate a non-selective cation channel upon osmotic cell shrinkage. Further stimuli of channel activation include oxidative stress, energy depletion and extracellular removal of Cl-. The channel is permeable to Ca2+ and opening of the channel increases cytosolic [Ca2+]. Intriguing evidence points to a role of this channel in the elimination of erythrocytes by apoptosis. Ca2+ entering through the cation channel stimulates a scramblase, leading to breakdown of cell membrane phosphatidylserine asymmetry, and stimulates Ca(2+)-sensitive K+ channels, thus leading to KCl loss and (further) cell shrinkage. The breakdown of phosphatidylserine asymmetry is evidenced by annexin binding, a typical feature of apoptotic cells. The effects of osmotic shock, oxidative stress and energy depletion on annexin binding are mimicked by the Ca2+ ionophore ionomycin (1 microM) and blunted in the nominal absence of extracellular Ca2+. Nevertheless, the residual annexin binding points to additional mechanisms involved in the triggering of the scramblase. The exposure of phosphatidylserine at the extracellular face of the cell membrane stimulates phagocytes to engulf the apoptotic erythrocytes. Thus, sustained activation of the cation channels eventually leads to clearance of affected erythrocytes from peripheral blood. Susceptibility to annexin binding is enhanced in several genetic disorders affecting erythrocyte function, such as thalassaemia, sickle-cell disease and glucose-6-phosphate dehydrogenase deficiency. The enhanced vulnerability presumably contributes to the shortened life span of the affected erythrocytes. Beyond their role in the limitation of erythrocyte survival, cation channels may contribute to the triggering of apoptosis in nucleated cells exposed to osmotic shock and/or oxidative stress.
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Affiliation(s)
- Florian Lang
- Physiologisches Institut der Universität Tübingen, Gmelinstrasse 5, 72076 Tübingen, Germany.
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Lang KS, Roll B, Myssina S, Schittenhelm M, Scheel-Walter HG, Kanz L, Fritz J, Lang F, Huber SM, Wieder T. Enhanced erythrocyte apoptosis in sickle cell anemia, thalassemia and glucose-6-phosphate dehydrogenase deficiency. Cell Physiol Biochem 2003; 12:365-72. [PMID: 12438773 DOI: 10.1159/000067907] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Erythrocyte diseases such as sickle cell anemia, thalassemia and glucose-6-phosphate dehydrogenase deficiency decrease the erythrocyte life span, an effect contributing to anemia. Most recently, erythro-cytes have been shown to undergo apoptosis upon increase of cytosolic Ca(2+) activity. The present study has been performed to explore whether sickle cell anemia, thalassemia and glucose-6-phosphate dehydrogenase deficiency enhance the sensitivity of erythrocytes to osmotic shock, oxidative stress or energy depletion, all maneuvers known to increase cytosolic Ca(2+) activity. To this end, annexin binding as an indicator of apoptosis has been determined by FACS analysis. Erythrocytes from healthy individuals, from patients with sickle cell anemia, thalassemia or glucose-6-phosphate dehydrogenase deficiency all responded to osmotic shock (up to 950 mOsm by addition of sucrose for 24 hours), to oxidative stress (up to 1.0 mM tetra-butyl-hydroxyperoxide tBOOH) and to energy depletion (up to 48 hours glucose deprivation) with enhanced annexin binding. However, the sensitivity of sickle cells and of glucose-6-phosphate dehydrogenase deficient cells to osmotic shock and of sickle cells, thalassemic cells and glucose-6-phosphate dehydrogenase deficient cells to oxidative stress and to glucose depletion was significantly higher than that of control cells. Annexin binding was further stimulated by Ca(2+) ionophore ionomycin with significantly higher sensitivity of sickle cells and glucose-6-phosphate dehydrogenase deficient cells as compared to intact cells. In conclusion, sickle cells, thalassemic cells and glucose-6-phosphate dehydrogenase deficient erythrocytes are more sensitive to osmotic shock, oxidative stress and/or energy depletion, thus leading to enhanced apoptosis of those cells. The accelerated apoptosis then contributes to the shortened life span of the defective erythrocytes.
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Affiliation(s)
- Karl S Lang
- Department of Physiology, University of Tuebingen, Germany
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Lang KS, Myssina S, Tanneur V, Wieder T, Huber SM, Lang F, Duranton C. Inhibition of erythrocyte cation channels and apoptosis by ethylisopropylamiloride. Naunyn Schmiedebergs Arch Pharmacol 2003; 367:391-6. [PMID: 12690431 DOI: 10.1007/s00210-003-0701-z] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2002] [Accepted: 01/21/2003] [Indexed: 12/16/2022]
Abstract
Even though lacking mitochondria and nuclei erythrocytes do undergo apoptotic cell death which is characterized by breakdown of phosphatidylserine asymmetry (leading to annexin binding), membrane blebbing and cell shrinkage. Previously, we have shown that erythrocyte apoptosis is triggered by osmotic shrinkage at least in part through activation of cell volume-sensitive cation channels and subsequent Ca2+ entry. The channels could not only be activated by cell shrinkage but as well by replacement of Cl- with gluconate. Both, channel activity and annexin binding were sensitive to high concentrations of amiloride (1 mM). The present study has been performed to search for more effective blockers. To this end channel activity has been evaluated utilizing whole-cell patch-clamp and annexin binding determined by FACS analysis as an indicator of erythrocyte apoptosis. It is shown that either, increase of osmolarity or replacement of Cl- by gluconate triggers the activation of the cation channel which is inhibited by amiloride at 1 mM but not at 100 microM. Surprisingly, the cation channel was significantly more sensitive to the amiloride analogue ethylisopropylamiloride (EIPA, IC(50)=0.6+/-0.1 microM, n=5). Exposure of the cells to osmotic shock by addition of sucrose (850 mOsm) led to stimulation of annexin binding which was inhibited similarly by EIPA (IC(50)=0.2+/-0.2 microM, n=4). Moreover, annexin binding was inhibited by higher concentrations of HOE 642 (IC(50)=10+/-5 microM, n=5) and HOE 694 (IC(50)=12+/-6 microM, n=4). It is concluded that osmotic shock stimulates a cation channel which participates in the triggering of erythrocyte apoptosis. EIPA is an effective inhibitor of this cation channel and of channel mediated triggering of erythrocyte apoptosis.
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Affiliation(s)
- K S Lang
- Department of Physiology, University of Tübingen, Gmelinstrasse 5, 72076 Tübingen, Germany.
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Lang KS, Duranton C, Poehlmann H, Myssina S, Bauer C, Lang F, Wieder T, Huber SM. Cation channels trigger apoptotic death of erythrocytes. Cell Death Differ 2003; 10:249-56. [PMID: 12700653 DOI: 10.1038/sj.cdd.4401144] [Citation(s) in RCA: 253] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Erythrocytes are devoid of mitochondria and nuclei and were considered unable to undergo apoptosis. As shown recently, however, the Ca(2+)-ionophore ionomycin triggers breakdown of phosphatidylserine asymmetry (leading to annexin binding), membrane blebbing and shrinkage of erythrocytes, features typical for apoptosis in nucleated cells. In the present study, the effects of osmotic shrinkage and oxidative stress, well-known triggers of apoptosis in nucleated cells, were studied. Exposure to 850 mOsm for 24 h, to tert-butyl-hydroperoxide (1 mM) for 15 min, or to glucose-free medium for 48 h, all elicit erythrocyte shrinkage and annexin binding, both sequelae being blunted by removal of extracellular Ca(2+) and mimicked by ionomycin (1 microM). Osmotic shrinkage and oxidative stress activate Ca(2+)-permeable cation channels and increase cytosolic Ca(2+) concentration. The channels are inhibited by amiloride (1 mM), which further blunts annexin binding following osmotic shock, oxidative stress and glucose depletion. In conclusion, osmotic and oxidative stress open Ca(2+)-permeable cation channels in erythrocytes, thus increasing cytosolic Ca(2+) activity and triggering erythrocyte apoptosis.
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Affiliation(s)
- K S Lang
- Department of Physiology, University of Tübingen, Tübingen, Germany
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