Phosphorylation of eIF-4E on Ser 209 in Response to Mitogenic and Inflammatory Stimuli Is Faithfully Detected by Specific Antibodies

Tschopp, Claude; Knauf, Ursula; Brauchle, Maria; Zurini, Mauro; Ramage, Paul; Glueck, D.; New, Liguo; Han, Jiahuai; Gram, Hermann

doi:10.1006/mcbr.2000.0217

Cited by 58 publications

(51 citation statements)

References 27 publications

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“…Rabbit polyclonal antibodies that specifically recognize the Ser209-phosphorylated version of eIF4E were generated as described elsewhere (36). Monoclonal anti-eIF4E and anti-eIF4G antibodies were purchased from Transduction Laboratories (Lexington, Ky.).…”

Section: Methodsmentioning

confidence: 99%

“…and Santa Cruz Biotechnology (Santa Cruz, Calif.), respectively. Western blotting of SDS-PAGE was performed as described elsewhere (36). The p38 MAP kinase inhibitor SB203580 and the MEK inhibitor U0126 were obtained from Calbiochem (La Jolla, Calif.).…”

Section: Methodsmentioning

confidence: 99%

“…The p38 MAP kinase inhibitor SB203580 and the MEK inhibitor U0126 were obtained from Calbiochem (La Jolla, Calif.). CGP57380 was identified from the Novartis Pharma compound collection by in vitro kinase assays (36).…”

Section: Methodsmentioning

confidence: 99%

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Negative Regulation of Protein Translation by Mitogen-Activated Protein Kinase-Interacting Kinases 1 and 2

Knauf

Tschopp

Gram

2001

Molecular and Cellular Biology

232

188

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Eukaryotic initiation factor 4E (eIF4E) is a key component of the translational machinery and an important modulator of cell growth and proliferation. The activity of eIF4E is thought to be regulated by interaction with inhibitory binding proteins (4E-BPs) and phosphorylation by mitogen-activated protein (MAP) kinase-interacting kinase (MNK) on Ser209 in response to mitogens and cellular stress. Here we demonstrate that phosphorylation of eIF4E via MNK1 is mediated via the activation of either the Erk or p38 pathway. We further show that expression of active mutants of MNK1 and MNK2 in 293 cells diminishes cap-dependent translation relative to cap-independent translation in a transient reporter assay. The same effect on cap-dependent translation was observed when MNK1 was activated by the Erk or p38 pathway. In line with these findings, addition of recombinant active MNK1 to rabbit reticulocyte lysate resulted in a reduced protein synthesis in vitro, and overexpression of MNK2 caused a decreased rate of protein synthesis in 293 cells. By using CGP 57380, a novel low-molecular-weight kinase inhibitor of MNK1, we demonstrate that eIF4E phosphorylation is not crucial to the formation of the initiation complex, mitogen-stimulated increase in cap-dependent translation, and cell proliferation. Our results imply that activation of MNK by MAP kinase pathways does not constitute a positive regulatory mechanism to cap-dependent translation. Instead, we propose that the kinase activity of MNKs, eventually through phosphorylation of eIF4E, may serve to limit cap-dependent translation under physiological conditions.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Negative Regulation of Protein Translation by Mitogen-Activated Protein Kinase-Interacting Kinases 1 and 2

Knauf

Tschopp

Gram

2001

Molecular and Cellular Biology

232

188

View full text Add to dashboard Cite

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“…MAPks phosphorylate and activate a kinase called MAPK integrating kinase (Mnk), which phosphorylate the translational initiation factor eIF4E (Pyronnet et al, 1999). Culture conditions which induce cellular stress also increase the phosphorylation of eIF4E (Wang et al, 1998;Tschopp et al, 2000). This effect appears to be specifically induced by the p38 MAP kinase pathway (Morley and McKendrick, 1997).…”

Section: Possible Mechanisms Of Translation Initiationmentioning

confidence: 99%

Comparison of the molecular effects of the mycotoxins β-zearalenol and deoxynivalenol in porcine endometrial cells — A review

Wollenhaupt

Tomek

Tiemann

2007

Acta Veterinaria Hungarica

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The mycotoxins β-zearalenol (β-ZOL) and deoxynivalenol (DON) produce toxic effects that result in diseases in humans and animals. The molecular mechanisms that control the mycotoxin-mediated effects are far from being completely understood. Various results show that these mycotoxins could inhibit cell proliferation. In the present short communication, the influence of β-ZOL and DON on the abundance and phosphorylation state of kinases that are included in regulation of the initiation of mRNA translation (which is correlated with cell proliferation) was compared in porcine endometrial cells (PEC). Our results indicate that these mycotoxins modulate the expression and phosphorylation of these factors in a different manner. Whereas β-ZOL mainly had an impact on the biological activity of the extracellular signal-regulated protein kinases 1 and 2 (ERK1/2), protein kinase B (Akt), eukaryotic initiation factor 4E (eIF4E) and its repressor 4E binding protein 1 (4E-BP1), DON reduced the abundance of p38 MAPk, Akt and specific 4E-BP1 bands. In summary, these results indicate that β-ZOL influences molecular events that are included in the initiation of mRNA translation in the porcine endometrium but DON does not alter such processes clearly.

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“…G-CSF was freshly added every 48 h. When indicated, the cells were also exposed to 10 mM CGP57380. CGP57380, a novel low-molecular-weight MNK1/2 kinase inhibitor, was kindly provided by Novartis (Tschopp et al, 2000). After 8 days, cells were washed with PBS, resuspended in 100 ml PBS and incubated with the (PE-labeled) anti-CD 11b antibody (clone M1/70.15.1, Cymbus Biotechnology) for 30 min on ice.…”

Section: Differentiation Of Myeloid Leukemia Cell Linesmentioning

confidence: 99%

The serine-threonine kinase MNK1 is post-translationally stabilized by PML-RARα and regulates differentiation of hematopoietic cells

et al. 2004

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Microarray analyses were performed to identify target genes that are shared by the acute myeloid leukemia (AML) translocation products PML-RARa, PLZFRARa and AML1-ETO in inducibly transfected U937 cell lines. The cytoplasmic serine and threonine kinase MNK1 was identified as one of the target genes. At the protein level, MNK1 was significantly induced by each of the three fusion proteins. Protein half-life analyses showed that PML-RARa enhanced MNK1 protein stability in U937 cells and ATRA exposure decreased MNK1 halflife in NB4 cells. EIF4E, the main MNK1 substrate, plays a role in the pathogenesis of a variety of cancers. Upon MNK1 overexpression, eIF4E phosphorylation increased as a sign of functional activation. Interestingly, MNK1 protein expression decreased during myeloid differentiation. Inhibition of MNK1 activity by a specific inhibitor (CGP57380) enhanced differentiation of HL60 and 32D cells, further suggesting a role for MNK1 in the myeloid differentiation. In addition, kinase dead mutants of MNK1 significantly impaired proliferation of 32D cells. Immunohistochemistry of primary AML bone marrow biopsies showed strong cytoplasmic MNK1 expression in 25 of 99 AML specimens (25%). MNK1 expression was associated with high levels of c-myc expression. Taken together, we identified MNK1 as a target gene of several leukemogenic fusion proteins in AML. MNK1 plays a role in myeloid differentiation. These data suggest a role for MNK1 in the AML fusion protein-associated differentiation block.

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Phosphorylation of eIF-4E on Ser 209 in Response to Mitogenic and Inflammatory Stimuli Is Faithfully Detected by Specific Antibodies

Cited by 58 publications

References 27 publications

Negative Regulation of Protein Translation by Mitogen-Activated Protein Kinase-Interacting Kinases 1 and 2

Negative Regulation of Protein Translation by Mitogen-Activated Protein Kinase-Interacting Kinases 1 and 2

Comparison of the molecular effects of the mycotoxins β-zearalenol and deoxynivalenol in porcine endometrial cells — A review

The serine-threonine kinase MNK1 is post-translationally stabilized by PML-RARα and regulates differentiation of hematopoietic cells

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