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  • 1
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    Growth factor-dependent proliferative stimulation of hematopoietic cells is associated with the modulation of cytoplasmic and nuclear 68- Kd calmodulin-binding protein (1992)
    American Society of Hematology
    Details
    Publication Date: 1992-04-15
    Description: Calcium and calmodulin (CaM) are known to play critical roles in controlling cell cycle progression in a variety of cells. We observed that the CaM antagonist, N-(6-aminohexyl)-5-chloro-1- naphthalensulfonamide hydrochloride (W-7), inhibited 3H-thymidine incorporation into DNA of factor-dependent hematopoietic cells. To delineate the role of CaM in proliferation of hematopoietic cells, we have investigated intracellular distribution of specific CaM-binding proteins (CaM-BPs) in response to hematopoietic growth factors in FDC- P1, 32D, NFS-60, and T1165 cells. Each of these cell lines, when deprived of cytokines for 16 to 18 hours, essentially ceased proliferation, even in the presence of fetal calf serum. Concomitant to the cessation of proliferation, there was a dramatic depletion of a specific CaM-BP of about 68 Kd in both their cytoplasmic and nuclear fractions. Within 6 to 12 hours of reexposure to proliferation-specific cytokines, there was a restoration of the nuclear as well as cytoplasmic 68-Kd CaM-BP. Furthermore, such an induction and nuclear localization of the 68-Kd CaM-BP by the cytokines coincided temporally with the progression of synchronized FDC-P1 cells from G1 to S phase. By contrast, colony-stimulating factor-1 (CSF-1)-dependent bone marrow macrophages and BAC-1 cells did not exhibit 68-Kd CaM-BP in the nuclear or cytoplasmic fractions. These studies suggest that while hematopoietic growth factor granulocyte CSF-, granulocyte-macrophage CSF-, interleukin-3 (IL-3)-, or IL-6-, whose receptors are members of the hematopoietin receptor family, induced cell proliferation is associated with a common mechanism involving nuclear localization of the 68-Kd CaM-BP, the CSF-1-induced proliferation seems to involve 68- Kd CaM-BP-independent pathways.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 2
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    Nonrandom association of free iron with membranes of sickle and beta- thalassemic erythrocytes (1993)
    American Society of Hematology
    Details
    Publication Date: 1993-11-15
    Description: To further define the nature of abnormal iron deposits on the membranes of pathologic red blood cells, we have used sickle cell anemia (HbSS), HbSC, and beta-thalassemic erythrocytes (RBCs) to prepare inside-out membranes (IOM) and insoluble membrane aggregates (AGGs) containing coclustered hemichrome and band 3. Study of IOM from HbSC and thalassemic patients showed that amounts of heme iron and, especially, free iron were much higher in patients who had undergone surgical splenectomy. The membrane AGGs from HbSS and beta-thalassemic RBCs contained much more globin than heme, with this discrepancy being variable from patient to patient. Although these AGGs were enriched (compared with the ghosts from which they were derived) for heme, as expected, less than 10% of total ghost heme was recovered in them. Remarkably, these AGGs also were enriched for nonheme iron, markedly so in some patients. Iron binding studies showed that the association of free iron with these hemichrome/band 3 AGGs is explained by the fact that free iron binds to denatured hemoglobin. These results document that free iron is nonrandomly associated with the membranes of sickle and beta-thalassemic RBCs. Whether this plays a causative role in the premature removal of such cells from the circulation remains to be seen.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 3
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    Nonrandom association of free iron with membranes of sickle and beta- thalassemic erythrocytes (1993)
    American Society of Hematology
    Details
    Publication Date: 1993-11-15
    Description: To further define the nature of abnormal iron deposits on the membranes of pathologic red blood cells, we have used sickle cell anemia (HbSS), HbSC, and beta-thalassemic erythrocytes (RBCs) to prepare inside-out membranes (IOM) and insoluble membrane aggregates (AGGs) containing coclustered hemichrome and band 3. Study of IOM from HbSC and thalassemic patients showed that amounts of heme iron and, especially, free iron were much higher in patients who had undergone surgical splenectomy. The membrane AGGs from HbSS and beta-thalassemic RBCs contained much more globin than heme, with this discrepancy being variable from patient to patient. Although these AGGs were enriched (compared with the ghosts from which they were derived) for heme, as expected, less than 10% of total ghost heme was recovered in them. Remarkably, these AGGs also were enriched for nonheme iron, markedly so in some patients. Iron binding studies showed that the association of free iron with these hemichrome/band 3 AGGs is explained by the fact that free iron binds to denatured hemoglobin. These results document that free iron is nonrandomly associated with the membranes of sickle and beta-thalassemic RBCs. Whether this plays a causative role in the premature removal of such cells from the circulation remains to be seen.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
    Location Call Number Expected Availability
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    PAPER CURRENT
  • 4
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    Unknown
    Growth factor-dependent proliferative stimulation of hematopoietic cells is associated with the modulation of cytoplasmic and nuclear 68- Kd calmodulin-binding protein (1992)
    American Society of Hematology
    Details
    Publication Date: 1992-04-15
    Description: Calcium and calmodulin (CaM) are known to play critical roles in controlling cell cycle progression in a variety of cells. We observed that the CaM antagonist, N-(6-aminohexyl)-5-chloro-1- naphthalensulfonamide hydrochloride (W-7), inhibited 3H-thymidine incorporation into DNA of factor-dependent hematopoietic cells. To delineate the role of CaM in proliferation of hematopoietic cells, we have investigated intracellular distribution of specific CaM-binding proteins (CaM-BPs) in response to hematopoietic growth factors in FDC- P1, 32D, NFS-60, and T1165 cells. Each of these cell lines, when deprived of cytokines for 16 to 18 hours, essentially ceased proliferation, even in the presence of fetal calf serum. Concomitant to the cessation of proliferation, there was a dramatic depletion of a specific CaM-BP of about 68 Kd in both their cytoplasmic and nuclear fractions. Within 6 to 12 hours of reexposure to proliferation-specific cytokines, there was a restoration of the nuclear as well as cytoplasmic 68-Kd CaM-BP. Furthermore, such an induction and nuclear localization of the 68-Kd CaM-BP by the cytokines coincided temporally with the progression of synchronized FDC-P1 cells from G1 to S phase. By contrast, colony-stimulating factor-1 (CSF-1)-dependent bone marrow macrophages and BAC-1 cells did not exhibit 68-Kd CaM-BP in the nuclear or cytoplasmic fractions. These studies suggest that while hematopoietic growth factor granulocyte CSF-, granulocyte-macrophage CSF-, interleukin-3 (IL-3)-, or IL-6-, whose receptors are members of the hematopoietin receptor family, induced cell proliferation is associated with a common mechanism involving nuclear localization of the 68-Kd CaM-BP, the CSF-1-induced proliferation seems to involve 68- Kd CaM-BP-independent pathways.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
    Location Call Number Expected Availability
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    PAPER CURRENT
  • 5
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    Serum form of the erythropoietin receptor identified by a sequence- specific peptide antibody [see comments] (1993)
    American Society of Hematology
    Details
    Publication Date: 1993-10-01
    Description: The present investigation was undertaken to search for soluble forms of the erythropoietin receptor in human serum using polyclonal antibody against an amino terminal peptide sequence in the extracellular domain. This sequence was located adjacent to the amino terminus at residues 25- 38. When this antibody was used for Western blots of solubilized membranes from nucleated bone marrow cells, a protein consistent with native erythropoietin receptor was seen. Purified soluble ectodomain of the erythropoietin receptor displayed appropriate reactivity with this antibody. When sera from normal subjects and patients with a range of hematologic disorders were examined by Western blotting, a protein with a molecular mass of 34 Kd was detected in sera from patients with enhanced erythropoiesis including sickle cell anemia, thalassemia, and megaloblastic anemia. This protein was rarely detected in normal serum but appeared when normal subjects were treated with recombinant erythropoietin and disappeared after full treatment of patients with megaloblastic anemia due to vitamin B12 deficiency. The protein was not detected after myeloablation for bone marrow transplantation but appeared with marrow engraftment. Reactivity of this protein with the peptide antibody was competitively inhibited by the amino terminal peptide sequence. An additional 48 Kd protein was detected that showed minimal variation in intensity with differing degrees of erythropoietic activity. Detection of this protein could not be inhibited by the addition of synthetic peptide. Our findings indicate the presence of a soluble form of the erythropoietin receptor related to the extracellular domain that is highly correlated with enhanced erythropoiesis.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
    Location Call Number Expected Availability
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  • 6
    facet.materialart.
    Unknown
    Serum form of the erythropoietin receptor identified by a sequence- specific peptide antibody [see comments] (1993)
    American Society of Hematology
    Details
    Publication Date: 1993-10-01
    Description: The present investigation was undertaken to search for soluble forms of the erythropoietin receptor in human serum using polyclonal antibody against an amino terminal peptide sequence in the extracellular domain. This sequence was located adjacent to the amino terminus at residues 25- 38. When this antibody was used for Western blots of solubilized membranes from nucleated bone marrow cells, a protein consistent with native erythropoietin receptor was seen. Purified soluble ectodomain of the erythropoietin receptor displayed appropriate reactivity with this antibody. When sera from normal subjects and patients with a range of hematologic disorders were examined by Western blotting, a protein with a molecular mass of 34 Kd was detected in sera from patients with enhanced erythropoiesis including sickle cell anemia, thalassemia, and megaloblastic anemia. This protein was rarely detected in normal serum but appeared when normal subjects were treated with recombinant erythropoietin and disappeared after full treatment of patients with megaloblastic anemia due to vitamin B12 deficiency. The protein was not detected after myeloablation for bone marrow transplantation but appeared with marrow engraftment. Reactivity of this protein with the peptide antibody was competitively inhibited by the amino terminal peptide sequence. An additional 48 Kd protein was detected that showed minimal variation in intensity with differing degrees of erythropoietic activity. Detection of this protein could not be inhibited by the addition of synthetic peptide. Our findings indicate the presence of a soluble form of the erythropoietin receptor related to the extracellular domain that is highly correlated with enhanced erythropoiesis.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
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