scholarly journals Phosphatidylinositol-3-kinase activity is required for the anti-ig- mediated growth inhibition of a human B-lymphoma cell line

Blood ◽  
1996 ◽  
Vol 87 (1) ◽  
pp. 202-210 ◽  
Author(s):  
M Beckwith ◽  
RG Fenton ◽  
IM Katona ◽  
DL Longo
Keyword(s):  
Growth Inhibition ◽  
Tyrosine Kinases ◽  
Specific Inhibitor ◽  
Phosphatidylinositol 3 Kinase ◽  
Intact Cells ◽  
B Lymphoma ◽  
Cycle Arrest ◽  
Pi3k Activity ◽  
B Lymphoma Cells ◽  
Phosphatidylinositol 3

Abstract Stimulation of B lymphocytes through the Ig receptor initiates a cascade of biochemical changes, which can ultimately lead to either activation and growth, or cell-cycle arrest and cell death. One of the critical events that occurs in both cases is the activation of tyrosine kinases, and the resulting phosphorylation of a variety of proteins on tyrosine residues. In this report we identify one of the substrates of phosphorylation as the 85-kD subunit of the enzyme phosphatidylinositol-3 kinase (PI3K), and show that both anti-IgM and anti-IgD stimulation results in an increase in the anti-phosphotyrosine-precipitable PI3K activity. Furthermore, we show that the potent and specific inhibitor of PI3K, Wortmannin, can completely abrogate anti-Ig-mediated growth inhibition without affecting tyrosine kinase induction or protein kinase C (PKC) activation. Treatment of intact cells with Wortmannin results in an irreversible decrease in anti-Ig-induced PI3K activity, suggesting that the effect of Wortmannin on anti-Ig-mediated growth inhibition is caused by its inactivation of PI3K activity. Taken together, these data show that activation of PI3K is a critical component of the anti-Ig-initiated signaling cascade that leads to growth inhibition of human B lymphoma cells.

scholarly journals Phosphatidylinositol-3-kinase activity is required for the anti-ig- mediated growth inhibition of a human B-lymphoma cell line

Blood ◽  
1996 ◽  
Vol 87 (1) ◽  
pp. 202-210 ◽  
Author(s):  
M Beckwith ◽  
RG Fenton ◽  
IM Katona ◽  
DL Longo
Keyword(s):  
Growth Inhibition ◽  
Tyrosine Kinases ◽  
Specific Inhibitor ◽  
Phosphatidylinositol 3 Kinase ◽  
Intact Cells ◽  
B Lymphoma ◽  
Cycle Arrest ◽  
Pi3k Activity ◽  
B Lymphoma Cells ◽  
Phosphatidylinositol 3

Stimulation of B lymphocytes through the Ig receptor initiates a cascade of biochemical changes, which can ultimately lead to either activation and growth, or cell-cycle arrest and cell death. One of the critical events that occurs in both cases is the activation of tyrosine kinases, and the resulting phosphorylation of a variety of proteins on tyrosine residues. In this report we identify one of the substrates of phosphorylation as the 85-kD subunit of the enzyme phosphatidylinositol-3 kinase (PI3K), and show that both anti-IgM and anti-IgD stimulation results in an increase in the anti-phosphotyrosine-precipitable PI3K activity. Furthermore, we show that the potent and specific inhibitor of PI3K, Wortmannin, can completely abrogate anti-Ig-mediated growth inhibition without affecting tyrosine kinase induction or protein kinase C (PKC) activation. Treatment of intact cells with Wortmannin results in an irreversible decrease in anti-Ig-induced PI3K activity, suggesting that the effect of Wortmannin on anti-Ig-mediated growth inhibition is caused by its inactivation of PI3K activity. Taken together, these data show that activation of PI3K is a critical component of the anti-Ig-initiated signaling cascade that leads to growth inhibition of human B lymphoma cells.

scholarly journals Neurite outgrowth of PC12 cells is suppressed by wortmannin, a specific inhibitor of phosphatidylinositol 3-kinase.

1994 ◽  
Vol 269 (29) ◽  
pp. 18961-18967
Author(s):  
K. Kimura ◽  
S. Hattori ◽  
Y. Kabuyama ◽  
Y. Shizawa ◽  
J. Takayanagi ◽  
...  
Keyword(s):  
Neurite Outgrowth ◽  
Pc12 Cells ◽  
Specific Inhibitor ◽  
Phosphatidylinositol 3 Kinase ◽  
Phosphatidylinositol 3

scholarly journals Inhibition of kinases impairs neutrophil activation and killing of Staphylococcus aureus

1998 ◽  
Vol 331 (2) ◽  
pp. 489-495 ◽  
Author(s):  
Bruno SCHNYDER ◽  
Paul C. MEUNIER ◽  
Bruce D. CAR
Keyword(s):  
Staphylococcus Aureus ◽  
Map Kinases ◽  
Specific Inhibitor ◽  
Neutrophil Function ◽  
Oxygen Radical ◽  
Polymorphonuclear Neutrophils ◽  
Detectable Effect ◽  
Phosphatidylinositol 3 Kinase ◽  
Radical Generation ◽  
Phosphatidylinositol 3

Intracellular phosphorylations polymorphonuclear neutrophils are mediated by kinases, including mitogen activated-protein (MAP) kinases and phosphatidylinositol 3-kinase. In the present study we demonstrate their effector functions upon both ligation of cell-surface seven-transmembrane-spanning receptors by bacterial peptide formylmethionyl-leucylphenylalanine as well as in the process of destruction of Staphylococcus aureus. To regulate neutrophil MAP kinases p38 and p44/42, specifically, we made use of their specific inhibitors 10 µM SK&F 86002 (for p38) and PD 098059 (for activating kinase of p44/42). SK&F 86002 was a potent inhibitor (by 70%) of induced antimicrobial oxygen-radical generation compared with PD 098059 (by 20%). SK&F 86002 and PD 098059 inhibited mobilization of a dominant neutrophil adhesion molecule, β2 integrin, from cytoplasmic granules to the plasma membrane by 40 and 10% respectively, and the combination of the two drugs resulted in a 90% effect. The combined effect of both drugs was moderate inhibition of bacterial destruction, despite the fact that neither compound had detectable effect on bactericidal activity if applied individually. Bacterial destruction was also inhibited by wortmannin (0.1 µM), the specific inhibitor of phosphatidylinositol 3-kinase, which had previously been described to target various other activations of the neutrophil, including oxygen-radical generation. Although the relative contribution of p38 and p44/42 MAP kinases varied, the marked effects of the combined inhibition of the kinases revealed their concerted actions to be critical for normal neutrophil function.

scholarly journals c-Cbl Is Tyrosine-Phosphorylated by Interleukin-4 and Enhances Mitogenic and Survival Signals of Interleukin-4 Receptor by Linking With the Phosphatidylinositol 3′-Kinase Pathway

Blood ◽  
1998 ◽  
Vol 91 (1) ◽  
pp. 46-53 ◽  
Author(s):  
Hiroo Ueno ◽  
Ko Sasaki ◽  
Hiroaki Honda ◽  
Tetsuya Nakamoto ◽  
Tetsuya Yamagata ◽  
...  
Keyword(s):  
Specific Inhibitor ◽  
Pi3 Kinase ◽  
Interleukin 4 ◽  
Phosphatidylinositol 3 Kinase ◽  
Proliferation And Differentiation ◽  
Interleukin 4 Receptor ◽  
Pi3 Kinase Pathway ◽  
Kinase Pathway ◽  
Phosphatidylinositol 3 ◽  
Survival Signals

Interleukin-4 (IL-4) is a cytokine that induces both proliferation and differentiation and suppresses apoptosis of B cells. Although IL-4 has been shown to activate the phosphatidylinositol 3′ (PI3)-kinase pathway, the role of PI3 kinase in the IL-4 receptor (IL-4R) signaling remains unclear. In this study, we demonstrated that c-Cbl proto-oncogene product is inducibly phosphorylated on tyrosine residues and is associated with the p85 subunit of PI3-kinase by IL-4 stimulation. Overexpression of c-Cbl enhances the PI3-kinase activity and, at the same time, mitogenic activity and survival of cells in the presence of IL-4. However, these effects of c-Cbl were abolished by wortmannin, a specific inhibitor for the PI3 kinase pathway, or by a point mutation at tyrosine 731 of c-Cbl, which is a major binding site for p85. These results indicate that c-Cbl plays a role in linking IL-4R with the PI3 kinase pathway and thus enhancing the mitogenic and survival signals.

Phosphatidylinositol 3-Kinase and Prostaglandylinositol Cyclic Phosphate (Cyclic PIP), a Mediator of Insulin Action, in the Signal Transduction of Insulin

2000 ◽  
Vol 381 (11) ◽  
pp. 1139-1141 ◽  
Author(s):  
A. Gypakis ◽  
H.K. Wasner
Keyword(s):  
Insulin Receptor ◽  
Glucose Transport ◽  
Functional Role ◽  
Specific Inhibitor ◽  
Insulin Receptor Substrate ◽  
Phosphatidylinositol 3 Kinase ◽  
Downstream Signaling ◽  
Cyclic Phosphate ◽  
Phosphatidylinositol 3

Abstract It has been suggested that downstream signaling from the insulin receptor to the level of the protein kinases and protein phosphatases is accomplished by prostaglandylinositol cyclic phosphate (cyclic PIP), a proposed second messenger of insulin. However, evidence points also to both phosphatidylinositol 3-kinase, which binds to the tyrosine phosphorylated insulin receptor substrate-1, and the Ras complex in insulin's downstream signaling. We have examined whether a correlation exists between these various observations. It was found that wortmannin, a specific inhibitor of phosphatidylinositol 3-kinase, prevented insulin-induced, as well as cyclic PIP-induced activation of glucose transport, indicating that PI 3-kinase action on glucose transport involves downstream signaling of both insulin and cyclic PIP. Wortmannin has no effect on cyclic PIP synthase activity nor on the substrate production for cyclic PIP synthesis either, indicating that the functional role of PI 3-kinase is exclusively downstream of cyclic PIP.

scholarly journals Wortmannin, a specific inhibitor of phosphatidylinositol-3-kinase, induces accumulation of DNA double-strand breaks

2020 ◽  
Vol 61 (2) ◽  
pp. 171-176 ◽  
Author(s):  
Makoto Ihara ◽  
Kazuko Shichijo ◽  
Satoshi Takeshita ◽  
Takashi Kudo
Keyword(s):  
Dna Damage ◽  
Specific Inhibitor ◽  
Double Strand Breaks ◽  
Dependent Manner ◽  
Dna Double Strand Breaks ◽  
Phosphatidylinositol 3 Kinase ◽  
Strand Breaks ◽  
Γ Ray ◽  
Scid Cells ◽  
Phosphatidylinositol 3

Abstract Wortmannin, a fungal metabolite, is a specific inhibitor of the phosphatidylinositol 3-kinase (PI3K) family, which includes double-stranded DNA dependent protein kinase (DNA-PK) and ataxia telangiectasia mutated kinase (ATM). We investigated the effects of wortmannin on DNA damage in DNA-PK-deficient cells obtained from severe combined immunodeficient mice (SCID cells). Survival of wortmannin-treated cells decreased in a concentration-dependent manner. After treatment with 50 μM wortmannin, survival decreased to 60% of that of untreated cells. We observed that treatment with 20 and 50 μM wortmannin induced DNA damage equivalent to that by 0.37 and 0.69 Gy, respectively, of γ-ray radiation. The accumulation of DNA double-strand breaks (DSBs) in wortmannin-treated SCID cells was assessed using pulsed-field gel electrophoresis. The maximal accumulation was observed 4 h after treatment. Moreover, the presence of DSBs was confirmed by the ability of nuclear extracts from γ-ray-irradiated SCID cells to produce in vitro phosphorylation of histone H2AX. These results suggest that wortmannin induces cellular toxicity by accumulation of spontaneous DSBs through inhibition of ATM.

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