scholarly journals Erythropoietin induces tyrosine phosphorylation and activation of phospholipase C-gamma 1 in a human erythropoietin-dependent cell line.

1994 ◽  
Vol 269 (30) ◽  
pp. 19633-19638 ◽  
Author(s):  
H.Y. Ren ◽  
N. Komatsu ◽  
R. Shimizu ◽  
K. Okada ◽  
Y. Miura
Keyword(s):  
Phospholipase C ◽  
Cell Line ◽  
Tyrosine Phosphorylation ◽  
Human Erythropoietin ◽  
Dependent Cell ◽  
Phospholipase C Gamma

scholarly journals Erythropoietin rapidly induces tyrosine phosphorylation in the human erythropoietin-dependent cell line, UT-7

Blood ◽  
1992 ◽  
Vol 80 (1) ◽  
pp. 53-59 ◽  
Author(s):  
N Komatsu ◽  
JW Adamson ◽  
K Yamamoto ◽  
D Altschuler ◽  
M Torti ◽  
...  
Keyword(s):  
Cell Line ◽  
Tyrosine Phosphorylation ◽  
Dependent Manner ◽  
Guanosine Diphosphate ◽  
Human Erythropoietin ◽  
Early Signal ◽  
Dependent Cell ◽  
Macrophage Colony Stimulating Factor ◽  
Macrophage Colony ◽  
Stimulating Factor

Abstract UT-7 is a human megakaryoblastic cell line capable of growing in interleukin-3, granulocyte-macrophage colony-stimulating factor, or erythropoietin (Epo) (Cancer Res 51:341, 1991). We used this cell line and a selected Epo-dependent subcell line (UT-7/Epo) to study the early signal transduction events induced by Epo. When UT-7 cells were exposed to Epo, tyrosine phosphorylation of several proteins (with molecular weight equivalent to that of p85, p110, and p145) was observed. Protein phosphorylation occurred in both a dose- and time-dependent manner. p85 showed a marked increase in phosphotyrosine content within 30 seconds; maximal phosphorylation was observed at 1 minute. Subsequently, tyrosine phosphorylation of p110 and p145 was observed, beginning at 1 minute and reaching plateau at 5 minutes. The degree of phosphorylation of these three proteins gradually decreased thereafter. In addition, in UT-7/Epo cells, Epo induced tyrosine phosphorylation of other proteins that were not observed in Epo-induced UT-7 cells. The concentration of Epo required to induce tyrosine phosphorylation was in the same range of concentration required to stimulate cell growth. Epo was also able to activate p21ras as measured by exchange of guanosine diphosphate for guanosine triphosphate. These data show that tyrosine phosphorylation and P21ras activation are early signals in the Epo-induced mitogenic pathway.

scholarly journals Erythropoietin rapidly induces tyrosine phosphorylation in the human erythropoietin-dependent cell line, UT-7

Blood ◽  
1992 ◽  
Vol 80 (1) ◽  
pp. 53-59 ◽  
Author(s):  
N Komatsu ◽  
JW Adamson ◽  
K Yamamoto ◽  
D Altschuler ◽  
M Torti ◽  
...  
Keyword(s):  
Cell Line ◽  
Tyrosine Phosphorylation ◽  
Dependent Manner ◽  
Guanosine Diphosphate ◽  
Human Erythropoietin ◽  
Early Signal ◽  
Dependent Cell ◽  
Macrophage Colony Stimulating Factor ◽  
Macrophage Colony ◽  
Stimulating Factor

UT-7 is a human megakaryoblastic cell line capable of growing in interleukin-3, granulocyte-macrophage colony-stimulating factor, or erythropoietin (Epo) (Cancer Res 51:341, 1991). We used this cell line and a selected Epo-dependent subcell line (UT-7/Epo) to study the early signal transduction events induced by Epo. When UT-7 cells were exposed to Epo, tyrosine phosphorylation of several proteins (with molecular weight equivalent to that of p85, p110, and p145) was observed. Protein phosphorylation occurred in both a dose- and time-dependent manner. p85 showed a marked increase in phosphotyrosine content within 30 seconds; maximal phosphorylation was observed at 1 minute. Subsequently, tyrosine phosphorylation of p110 and p145 was observed, beginning at 1 minute and reaching plateau at 5 minutes. The degree of phosphorylation of these three proteins gradually decreased thereafter. In addition, in UT-7/Epo cells, Epo induced tyrosine phosphorylation of other proteins that were not observed in Epo-induced UT-7 cells. The concentration of Epo required to induce tyrosine phosphorylation was in the same range of concentration required to stimulate cell growth. Epo was also able to activate p21ras as measured by exchange of guanosine diphosphate for guanosine triphosphate. These data show that tyrosine phosphorylation and P21ras activation are early signals in the Epo-induced mitogenic pathway.

Increase of the catalytic activity of phospholipase C-gamma 1 by tyrosine phosphorylation

Science ◽  
1990 ◽  
Vol 250 (4985) ◽  
pp. 1253-1256 ◽  
Author(s):  
S Nishibe ◽  
M. Wahl ◽  
S. Hernandez-Sotomayor ◽  
N. Tonks ◽  
S. Rhee ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Phospholipase C ◽  
Tyrosine Phosphorylation ◽  
Phospholipase C Gamma

scholarly journals Phosphorylation and activation of epidermal growth factor receptors in cells transformed by the src oncogene.

1991 ◽  
Vol 11 (1) ◽  
pp. 309-321 ◽  
Author(s):  
W J Wasilenko ◽  
D M Payne ◽  
D L Fitzgerald ◽  
M J Weber
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Phospholipase C ◽  
Tyrosine Phosphorylation ◽  
Egf Receptor ◽  
Growth Factor Receptors ◽  
Epidermal Growth ◽  
Phospholipase C Gamma ◽  
Signaling Activity ◽  
In Cells

Because functionally significant substrates for the tyrosyl protein kinase activity of pp60v-src are likely to include membrane-associated proteins involved in normal growth control, we have tested the hypothesis that pp60v-src could phosphorylate and alter the signaling activity of transmembrane growth factor receptors. We have found that the epidermal growth factor (EGF) receptor becomes constitutively phosphorylated on tyrosine in cells transformed by the src oncogene and in addition displays elevated levels of phosphoserine and phosphothreonine. High-performance liquid chromatography phosphopeptide mapping revealed two predominant sites of tyrosine phosphorylation, both of which differed from the major sites of receptor autophosphorylation; thus, the src-induced phosphorylation is unlikely to occur via an autocrine mechanism. To determine whether pp60v-src altered the signaling activity of the EGF receptor, we analyzed the tyrosine phosphorylation of phospholipase C-gamma, since phosphorylation of this enzyme occurs in response to activation of the EGF receptor but not in response to pp60v-src alone. We found that in cells coexpressing pp60v-src and the EGF receptor, phospholipase C-gamma was constitutively phosphorylated, a result we interpret as indicating that the signaling activity of the EGF receptor was altered in the src-transformed cells. These findings suggest that pp60v-src-induced alterations in phosphorylation and function of growth regulatory receptors could play an important role in generating the phenotypic changes associated with malignant transformation.

scholarly journals Transfection of Syk protein tyrosine kinase reconstitutes high affinity IgE receptor-mediated degranulation in a Syk-negative variant of rat basophilic leukemia RBL-2H3 cells.

1996 ◽  
Vol 184 (1) ◽  
pp. 71-79 ◽  
Author(s):  
J Zhang ◽  
E H Berenstein ◽  
R L Evans ◽  
R P Siraganian
Keyword(s):  
Tyrosine Kinase ◽  
Histamine Release ◽  
Phospholipase C ◽  
Tyrosine Phosphorylation ◽  
Protein Tyrosine Kinase ◽  
Immunoglobulin E ◽  
Critical Role ◽  
Protein Tyrosine ◽  
High Affinity ◽  
Phospholipase C Gamma

Aggregation of the high affinity receptor for immunoglobulin E (Fc epsilon RI) on mast cells results in rapid tyrosine phosphorylation and activation of Syk, a cytoplasmic protein tyrosine kinase. To examine the role of Syk in the Fc epsilon RI signaling pathway, we identified a variant of RBL-2H3 cells that has no detectable Syk by immunoblotting and by in vitro kinase reactions. In these Syk-deficient TB1A2 cells, aggregation of Fc epsilon RI induced no histamine release and no detectable increase in total cellular protein tyrosine phosphorylation. However, stimulation of these cells with the calcium ionophore did induce degranulation. Fc epsilon RI aggregation induced tyrosine phosphorylation of the beta and gamma subunits of the receptor, but no increase in the tyrosine phosphorylation of phospholipase C-gamma 1 and phospholipase C-gamma 2 and no detectable increase in intracellular free Ca2+ concentration. By transfection, cloned lines were established with stable expression of Syk. In these reconstituted cells, Fc epsilon RI aggregation induced tyrosine phosphorylation of phospholipase C-gamma 1 and phospholipase C-gamma 2, an increase in intracellular free Ca2+ and histamine release. These results demonstrate that Syk plays a critical role in the early Fc epsilon RI-mediated signaling events. It further demonstrates that Syk activation occurs downstream of receptor phosphorylation, but upstream of most of the Fc epsilon RI-mediated protein tyrosine phosphorylations.

scholarly journals Tyrosine phosphorylation of Grb2-associated proteins correlates with phospholipase C gamma 1 activation in T cells.

1996 ◽  
Vol 16 (6) ◽  
pp. 2823-2829 ◽  
Author(s):  
D G Motto ◽  
M A Musci ◽  
S E Ross ◽  
G A Koretzky
Keyword(s):  
T Cell ◽  
Phospholipase C ◽  
Tyrosine Phosphorylation ◽  
Tyrosine Kinases ◽  
Inositol Phosphate ◽  
Critical Role ◽  
Chimeric Protein ◽  
Sh2 Domain ◽  
Mitogen Activated Protein Kinase ◽  
Phospholipase C Gamma

Ligation of the T-cell antigen receptor (TCR) results in the rapid activation of several protein tyrosine kinases, with the subsequent phosphorylation of numerous cellular proteins. We investigated the requirement for tyrosine phosphorylation of proteins which bind the Grb2 SH2 domain in TCR-mediated signal transduction by transfecting the Jurkat T-cell line with a cDNA encoding a chimeric protein designed to dephosphorylate these molecules. Stimulation of the TCR on cells expressing this engineered enzyme fails to result in sustained tyrosine phosphorylation of a 36-kDa protein likely to be the recently cloned pp36/Lnk. Interestingly, TCR ligation of the transfected cells also fails to induce soluble inositol phosphate production and intracellular calcium mobilization, although receptor-mediated tyrosine phosphorylation of phospholipase C gamma 1 still occurs. TCR-mediated Ras and mitogen-activated protein kinase activation remain intact in cells expressing the engineered phosphatase. These data demonstrate that tyrosine phosphorylation of a protein(s) which binds the SH2 domain of Grb2 correlates with phospholipase C gamma 1 activation and suggest that such a phosphoprotein(s) plays a critical role in coupling the TCR with the phosphatidylinositol second-messenger pathway.

scholarly journals Essential Role for Phospholipase C Gamma 1 (PLC-γ1) in the Survival of t(8;21) Acute Myeloid Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1699-1699 ◽  
Author(s):  
Hasan Mahmud ◽  
Frank JG Scherpen ◽  
Tiny Meeuwsen-de Boer ◽  
Harm-Jan Lourens ◽  
Eveline S. de Bont
Keyword(s):  
Cell Cycle ◽  
Acute Myeloid Leukemia ◽  
Phospholipase C ◽  
Cell Line ◽  
Myeloid Leukemia ◽  
Genetic Alterations ◽  
Therapeutic Strategies ◽  
Mrna Levels ◽  
Phospholipase C Gamma ◽  
Acute Myeloid

Abstract The t(8;21) (q22;q22) chromosomal translocation is one of the most frequent genetic alterations in acute myeloid leukemia (AML) and it remains a significant clinical problem especially for children which indicates the need for improved therapeutic strategies. Recently, we showed that peptide derived phospholipase C gamma 1 (PLC-γ1) was highly phosphorylated in pediatric t(8;21) AML. In this study, we determined PLC-γ1 phosphorylation and mRNA levels showing that PLC-γ1 expression was significantly higher in t(8;21) AML compared to other AML karyotypes and normal bone marrow (NBM) (peptide phosphorylation: p<0.01 compared to NBM, mRNA: p<0.001, compared to other AML karyotypes). This was confirmed by PLC-γ1 protein phosphorylation using primary AML samples and AML cell lines. PLC-γ1 is known to play a role in cancer progression, however, the impact of PLC-γ1 in AML is currently unknown. Therefore, we aimed to study the functional role of PLC-γ1 by investigating the cellular growth, survival and its underlying mechanism in a t(8;21) AML cell line (Kasumi-1) . ShRNA-mediated knockdown of PLC-γ1 in kasumi-1 cells significantly blocked leukemic cell growth at day 8 after transduction (p<0.05). The percentage of apoptosis in PLC-γ1 suppressed kasumi-1 cells at day 4 after transduction was two-fold higher compared to the scrambled control (p<0.01). The inhibition of cell proliferation and the induction of apoptosis upon PLC-γ1 suppression could be explained by cell cycle arrest and by increased activation of apoptotic related and cell cycle regulatory protein expressions (BAX, BCL2, p53 and Chk2). As the multidrug resistance is one of the major cause of relapse and poor prognosis in t(8;21) AML, therefore, we demonstrated, if PLC-γ1 suppression increased the sensitivity of kasumi-1 leukemia cells to cytotoxic chemotherapeutic agents (methotrexate, amsacrine and etoposide). PLC-γ1 knockdown cells at day 4 after transduction were shown to significantly reduced cell viability to the genotoxic agents, methotrexate (p<0.05, p<0.001), amsacrine (p<0.01, p<0.001) and etoposide (p<0.05, p<0.01 and p<0.001) in kasumi-1 in a dose-dependent manner. These results provide a strong rationale for the development of PLC-γ1-based therapeutic strategies for the enhancement of efficacy in t(8;21) AML treatment. Additionally, PLC-γ1 suppressed kasumi-1 cells showed significantly less proliferation upon hypoxic stress. Taken together, these results strongly support an important role for PLC-γ1 in the survival of t(8;21) AML mimicking kasumi-1 cell line and identify PLC-γ1 as a potential target for t(8;21) AML treatment. Disclosures No relevant conflicts of interest to declare.

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