scholarly journals Calcium regulates the commitment of murine erythroleukemia cells to terminal erythroid differentiation.

1981 ◽  
Vol 90 (2) ◽  
pp. 542-544 ◽  
Author(s):  
K Bridges ◽  
R Levenson ◽  
D Housman ◽  
L Cantley
Keyword(s):  
Calcium Transport ◽  
Calcium Ionophore ◽  
Chelating Agent ◽  
Erythroid Differentiation ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Erythroleukemia Cells ◽  
Time Required ◽  
Murine Erythroleukemia ◽  
Terminal Erythroid Differentiation

An alteration in the rate of calcium transport appears to be the rate-limiting event for the commitment of murine erythroleukemia (MEL) cells to initiate a program of terminal erythroid differentiation. The dimethyl sulfoxide (DMSO)-induced commitment of MEL cells to erythroid differentiation can be inhibited by treatment of cells with the calcium-chelating agent EGTA. Upon removal of EGTA, cells initiate commitment without the 12-h lag normally observed after treatment with DMSO alone. Treatment of cells with DMSO in the presence of calcium ionophore A23187 causes cells to initiate commitment from time zero with no lag. These results suggest that the lag is the time required for DMSO to alter the calcium transport properties of the cell.

scholarly journals Calcium ionophore, A23187, induces commitment to differentiation but inhibits the subsequent expression of erythroid genes in murine erythroleukemia cells

Blood ◽  
1991 ◽  
Vol 77 (6) ◽  
pp. 1362-1370 ◽  
Author(s):  
JO Hensold ◽  
G Dubyak ◽  
DE Housman
Keyword(s):  
Transcriptional Activation ◽  
Calcium Ionophore ◽  
Erythroid Differentiation ◽  
Cytosolic Calcium ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Cellular Processes ◽  
Cellular Events ◽  
Erythroleukemia Cells ◽  
Murine Erythroleukemia

Abstract Murine erythroleukemia (MEL) cells are a useful model for studying the processes that regulate erythroid differentiation because exposure of these cells to a variety of chemical inducing agents results in expression of erythroid-specific genes and the resultant loss of cellular immortality. Previously it has been suggested that the calcium ionophore, A23187, has effects on the early cellular events that lead to the commitment of these cells to differentiation, but was not in itself sufficient to induce differentiation. We demonstrate here that A23187, as well as another calcium ionophore, ionomycin, are capable of inducing commitment to differentiation. Unlike other inducing agents, continual exposure to A23187 inhibits transcription of the erythroid- specific genes, beta-globin and Band 3. This effect is not attributable to an increase in cytosolic calcium concentration, because cells induced by ionomycin produce normal amounts of hemoglobin. These effects of A23187 on MEL cells confirm that commitment to differentiation is a distinct event from the subsequent transcriptional activation of erythroid genes. The ability of both ionophores to induce commitment to differentiation suggests that an increase in cytosolic calcium can trigger commitment to differentiation. These agents should prove useful in investigating the cellular processes that are responsible for commitment to differentiation.

scholarly journals Calcium ionophore, A23187, induces commitment to differentiation but inhibits the subsequent expression of erythroid genes in murine erythroleukemia cells

Blood ◽  
1991 ◽  
Vol 77 (6) ◽  
pp. 1362-1370 ◽  
Author(s):  
JO Hensold ◽  
G Dubyak ◽  
DE Housman
Keyword(s):  
Transcriptional Activation ◽  
Calcium Ionophore ◽  
Erythroid Differentiation ◽  
Cytosolic Calcium ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Cellular Processes ◽  
Cellular Events ◽  
Erythroleukemia Cells ◽  
Murine Erythroleukemia

Murine erythroleukemia (MEL) cells are a useful model for studying the processes that regulate erythroid differentiation because exposure of these cells to a variety of chemical inducing agents results in expression of erythroid-specific genes and the resultant loss of cellular immortality. Previously it has been suggested that the calcium ionophore, A23187, has effects on the early cellular events that lead to the commitment of these cells to differentiation, but was not in itself sufficient to induce differentiation. We demonstrate here that A23187, as well as another calcium ionophore, ionomycin, are capable of inducing commitment to differentiation. Unlike other inducing agents, continual exposure to A23187 inhibits transcription of the erythroid- specific genes, beta-globin and Band 3. This effect is not attributable to an increase in cytosolic calcium concentration, because cells induced by ionomycin produce normal amounts of hemoglobin. These effects of A23187 on MEL cells confirm that commitment to differentiation is a distinct event from the subsequent transcriptional activation of erythroid genes. The ability of both ionophores to induce commitment to differentiation suggests that an increase in cytosolic calcium can trigger commitment to differentiation. These agents should prove useful in investigating the cellular processes that are responsible for commitment to differentiation.

Peptide models for protein-mediated cation transport

1980 ◽  
Vol 58 (10) ◽  
pp. 865-870 ◽  
Author(s):  
Charles M. Deber
Keyword(s):  
Calcium Transport ◽  
Calcium Ionophore ◽  
Cation Transport ◽  
Benzyl Ester ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Design And Synthesis ◽  
Cellular Processes ◽  
Naturally Occurring ◽  
Peptide Models

Substances which can perturb the transmembrane cation balance in a predictable manner have wide-ranging uses in the study of cellular processes. We have undertaken to examine transmembrane calcium transport on the molecular level through the design and synthesis of a series of ionophoric peptides as models for protein-mediated calcium transport. General mechanisms for carrier-mediated membrane transport are discussed. Cation transport profiles are presented for transport by synthetic peptides of structure cyclo(Glu(OR)-Sar-Gly-(N-R1)-Gly)2, where R = benzyl ester or H; R1 = n-decyl or cyclohexyl. Transport of physiologically abundant cations across "liquid membranes" in Pressman cells mediated by cyclo(Glu-Sar-Gly-(N-decyl)Gly)2 was observed to be essentially calcium specific, as long as calcium ions were present in the system. Multilamellar and unilamellar phosphatidylcholine vesicles were each found to be emptied of internal 45Ca2+ ions upon addition of cyclo(Glu(OBz)-Sar-Gly-(N-cyclohexyl)Gly)2 to the vesicle suspension. The results are compared with the naturally occurring calcium ionophore A23187.

scholarly journals Selective regulation of the Rab9-independent transport of ricin to the Golgi apparatus by calcium

2002 ◽  
Vol 115 (17) ◽  
pp. 3449-3456 ◽  
Author(s):  
Silje U. Lauvrak ◽  
Alicia Llorente ◽  
Tore-Geir Iversen ◽  
Kirsten Sandvig
Keyword(s):  
Golgi Apparatus ◽  
Calcium Transport ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Independent Process ◽  
Mannose 6 Phosphate ◽  
Phosphoinositide 3 Kinase ◽  
Modified Forms

Transport of ricin from endosomes to the Golgi apparatus occurs, in contrast to the transport of the mannose 6-phosphate receptor, by a Rab9-independent process. To characterize the pathway of ricin transport to the Golgi apparatus, we investigated whether it was regulated by calcium. As shown here, our data indicate that calcium is selectively involved in the regulation of ricin transport to the Golgi apparatus. Thapsigargin, which inhibits calcium transport into the ER, and the calcium ionophore A23187 both increased the transport of ricin to the Golgi apparatus by a factor of 20. By contrast, transport of the mannose 6-phosphate receptor to the Golgi apparatus was unaffected. Ricin and mannose 6-phosphate receptor transport were measured by quantifying the sulfation of modified forms of ricin and the mannose 6-phosphate receptor. The increased transport of ricin was reduced by wortmannin and LY294002, suggesting that phosphoinositide 3-kinase might be involved in transport of ricin to the Golgi apparatus. Together, these findings indicate that the different pathways to the Golgi apparatus utilized by ricin and the mannose 6-phosphate receptor are regulated by different mechanisms.

scholarly journals Developmental program of murine erythroleukemia cells. Effect of the inhibition of protein synthesis.

1979 ◽  
Vol 82 (3) ◽  
pp. 715-725 ◽  
Author(s):  
R Levenson ◽  
D Housman
Keyword(s):  
Protein Synthesis ◽  
Erythroid Differentiation ◽  
Developmental Program ◽  
Erythroleukemia Cells ◽  
Inhibition Of Protein Synthesis ◽  
Murine Erythroleukemia ◽  
The Relationship ◽  
Terminal Erythroid Differentiation ◽  
Inhibitor Treatment ◽  
Murine Erythroleukemia Cells

The relationship between protein synthesis and commitment to terminal erythroid differentiation by dimethylsulfoxide-treated murine erythroleukemia (MEL) cells has been studied. Treatment with cycloheximide blocks the commitment of MEL cells. The effects of cycloheximide are completely reversible, however. Treatment of MEL cells before commitment delays commitment for a period of time equal to the length of inhibitor treatment. Puromycin exerts a similar effect on the commitment of MEL cells. These results indicate that there is a continuous requirement for protein synthesis before the commitment event.

Growth factors and the primary cilium in BALB/c 3T3 cells

1987 ◽  
Vol 45 ◽  
pp. 830-831
Author(s):  
R. W. Tucker ◽  
N. S. More ◽  
S. Jayaraman
Keyword(s):  
Growth Factors ◽  
Primary Cilium ◽  
Cultured Cells ◽  
Morphological Changes ◽  
Calcium Ionophore ◽  
Growth Stimulation ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
3T3 Cells ◽  
Microtubule Depolymerization

The mechanisms by which polypeptide growth factors Induce DNA synthesis in cultured cells is not understood, but morphological changes Induced by growth factors have been used as clues to Intracellular messengers responsible for growth stimulation. One such morphological change has been the transient disappearance of the primary cilium, a “9 + 0” cilium formed by the perinuclear centriole in interphase cells. Since calcium ionophore A23187 also produced both mitogenesis and ciliary changes, microtubule depolymerization might explain ciliary disappearance monitored by indirect immunofluorescence with anti-tubulin antibody. However, complete resorption and subsequent reformation of the primary cilium occurs at mitosis, and might also account for ciliary disappearance induced by growth factors. To settle this issue, we investigated the ultrastructure of the primary cilium using serial thin-section electron microscopy of quiescent BALB/c 3T3 cells before and after stimulation with serum.

Inhibition of Platelet Aggregation by Ethanol in Vitro Shows Specificity for Aggregating Agent Used and Is Influenced by Platelet Lipid Composition

1982 ◽  
Vol 48 (01) ◽  
pp. 049-053 ◽  
Author(s):  
C G Fenn ◽  
J M Littleton
Keyword(s):  
Platelet Aggregation ◽  
Lipid Composition ◽  
Saturated Fatty Acids ◽  
Calcium Ionophore ◽  
Cholesterol Content ◽  
Membrane Lipid ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Increased Sensitivity

SummaryEthanol at physiologically tolerable concentrations inhibited platelet aggregation in vitro in a relatively specific way, which may be influenced by platelet membrane lipid composition. Aggregation to collagen, calcium ionophore A23187 and thrombin (low doses) were often markedly inhibited by ethanol, adrenaline and ADP responses were little affected, and aggregation to exogenous arachidonic acid was actually potentiated by ethanol. Aggregation to collagen, thrombin and A23187 was inhibited more by ethanol in platelets enriched with saturated fatty acids than in those enriched with unsaturated fats. Platelets enriched with cholesterol showed increased sensitivity to ADP, arachidonate and adrenaline but this increase in cholesterol content did not appear to influence the inhibition by ethanol of platelet responses. The results suggest that ethanol may inhibit aggregation by an effect on membrane fluidity and/or calcium mobilization resulting in decreased activity of a membrane-bound phospholipase.

scholarly journals miR-16-5p Promotes Erythroid Maturation of Erythroleukemia Cells by Regulating Ribosome Biogenesis

2021 ◽  
Vol 14 (2) ◽  
pp. 137
Author(s):  
Christos I. Papagiannopoulos ◽  
Nikoleta F. Theodoroula ◽  
Ioannis S. Vizirianakis
Keyword(s):  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Cultured Cells ◽  
Erythroid Differentiation ◽  
Underlying Mechanism ◽  
Loss Of Function ◽  
Functional Studies ◽  
Differentiated Cells ◽  
Erythroleukemia Cells ◽  
Murine Erythroleukemia

miRNAs constitute a class of non-coding RNA that act as powerful epigenetic regulators in animal and plant cells. In order to identify putative tumor-suppressor miRNAs we profiled the expression of various miRNAs during differentiation of erythroleukemia cells. RNA was purified before and after differentiation induction and subjected to quantitative RT-PCR. The majority of the miRNAs tested were found upregulated in differentiated cells with miR-16-5p showing the most significant increase. Functional studies using gain- and loss-of-function constructs proposed that miR-16-5p has a role in promoting the erythroid differentiation program of murine erythroleukemia (MEL) cells. In order to identify the underlying mechanism of action, we utilized bioinformatic in-silico platforms that incorporate predictions for the genes targeted by miR-16-5p. Interestingly, ribosome constituents, as well as ribosome biogenesis factors, were overrepresented among the miR-16-5p predicted gene targets. Accordingly, biochemical experiments showed that, indeed, miR-16-5p could modulate the levels of independent ribosomal proteins, and the overall ribosomal levels in cultured cells. In conclusion, miR-16-5p is identified as a differentiation-promoting agent in erythroleukemia cells, demonstrating antiproliferative activity, likely as a result of its ability to target the ribosomal machinery and restore any imbalanced activity imposed by the malignancy and the blockade of differentiation.

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