scholarly journals The vaccinia virus-stimulated mitogen-activated protein kinase (MAPK) pathway is required for virus multiplication

2004 ◽  
Vol 381 (2) ◽  
pp. 437-446 ◽  
Author(s):  
Anderson A. ANDRADE ◽  
Patrícia N. G. SILVA ◽  
Anna C. T. C. PEREIRA ◽  
Lirlândia P. de SOUSA ◽  
Paulo C. P. FERREIRA ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Vaccinia Virus ◽  
Mapk Pathway ◽  
Decisive Role ◽  
Virus Multiplication ◽  
Mitogen Activated Protein Kinase ◽  
Actin Dynamics ◽  
Kinase Activation ◽  
Mitogen Activated Protein

Early events play a decisive role in virus multiplication. We have shown previously that activation of MAPK/ERK1/2 (mitogen-activated protein kinase/extracellular-signal-regulated kinase 1/2) and protein kinase A are pivotal for vaccinia virus (VV) multiplication [de Magalhães, Andrade, Silva, Sousa, Ropert, Ferreira, Kroon, Gazzinelli and Bonjardim (2001) J. Biol. Chem. 276, 38353–38360]. In the present study, we show that VV infection provoked a sustained activation of both ERK1/2 and RSK2 (ribosomal S6 kinase 2). Our results also provide evidence that this pattern of kinase activation depends on virus multiplication and ongoing protein synthesis and is maintained independently of virus DNA synthesis. It is noteworthy that the VGF (VV growth factor), although involved, is not essential for prolonged ERK1/2 activation. Furthermore, our findings suggest that the VV-stimulated ERK1/2 activation also seems to require actin dynamics, microtubule polymerization and tyrosine kinase phosphorylation. The VV-stimulated pathway MEK/ERK1/2/RSK2 (where MEK stands for MAPK/ERK kinase) leads to phosphorylation of the ternary complex factor Elk-1 and expression of the early growth response (egr-1) gene, which kinetically paralleled the kinase activation. The recruitment of this pathway is biologically relevant, since its disruption caused a profound effect on viral thymidine kinase gene expression, viral DNA replication and VV multiplication. This pattern of sustained kinase activation after VV infection is unique. In addition, by connecting upstream signals generated at the cytoskeleton and by tyrosine kinase, the MEK/ERK1/2/RSK2 cascade seems to play a decisive role not only at early stages of the infection, i.e. post-penetration, but is also crucial to define the fate of virus progeny.

scholarly journals Analysis of mitogen-activated protein kinase activation by naturally occurring splice variants of TrkC, the receptor for neurotrophin-3

1997 ◽  
Vol 322 (1) ◽  
pp. 193-198 ◽  
Author(s):  
Frank J. GUNN-MOORE ◽  
Alan G. WILLIAMS ◽  
Jeremy M. TAVARÉ
Keyword(s):  
Amino Acid ◽  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Splice Variants ◽  
Mitogen Activated Protein Kinase ◽  
Kinase Activation ◽  
High Affinity ◽  
Naturally Occurring ◽  
Neurotrophin 3 ◽  
Mitogen Activated Protein

TrkC is a receptor tyrosine kinase that binds neurotrophin-3(NT-3) with high affinity. A number of naturally occurring splice variants of TrkC exist, including one (TrkC.ki14) with a 14 amino acid insertion between subdomains VII and VIII of the tyrosine kinase domain. This kinase insert blocks the ability of NT-3 to stimulate neurite outgrowth in PC12 cells and proliferation in fibroblasts. The inserts also block the ability of TrkC to form a high-affinity complex with Shc and phospholipase Cγ(PLCγ) and the activation of PtdIns 3-kinase, and attenuates the sustained activation of mitogen-activated protein kinase (MAPK). In the current study we set out to determine whether the attenuation of the activation of MAPK by the insert was the result of the inability of TrkC to activate the ShcŐRas pathway, PtdIns 3-kinase activation, PLCγ activation, or a combination thereof. Experiments with the use of cell-permeant inhibitors argue against a major role for PLCγ and PtdIns 3-kinase in the activation of MAPK by TrkC. The introduction of the 14 amino acid kinase insert appeared to slow the kinetics of NT-3-stimulated Shc phosphorylation and ShcŐGrb2 association and reduce their magnitude; an effect which was associated with a delayed, and only transient, activation of MAPK. Taken together, our data suggest that the apparent defect in MAPK activation caused by the kinase insert may result predominantly from an inhibition of high-affinity Shc binding, although a role for PLCγ and PtdIns 3-kinase cannot be completely excluded.

scholarly journals Involvement of the protein tyrosine phosphatase SHP-1 in Ras-mediated activation of the mitogen-activated protein kinase pathway.

1996 ◽  
Vol 16 (11) ◽  
pp. 5955-5963 ◽  
Author(s):  
S Krautwald ◽  
D Büscher ◽  
V Kummer ◽  
S Buder ◽  
M Baccarini
Keyword(s):  
Signal Transduction ◽  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Mapk Pathway ◽  
Negative Regulator ◽  
Mitogen Activated Protein Kinase ◽  
Dependent Manner ◽  
Colony Stimulating Factor ◽  
Mitogen Activated Protein ◽  
Stimulating Factor

Ubiquitously expressed SH2-containing tyrosine phosphatases interact physically with tyrosine kinase receptors or their substrates and relay positive mitogenic signals via the activation of the Ras-mitogen-activated protein kinase (MAPK) pathway. Conversely, the structurally related phosphatase SHP-1 is predominantly expressed in hemopoietic cells and becomes tyrosine phosphorylated upon colony-stimulating factor 1 treatment of macrophages without associating with the colony-stimulating factor 1 receptor tyrosine kinase. Mice lacking functional SHP-1 (me/me and me(v)/me(v)) develop systemic autoimmune disease with accumulation of macrophages, suggesting that SHP-1 may be a negative regulator of hemopoietic cell growth. By using macrophages expressing dominant negative Ras and the me(v)/me(v) mouse mutant, we show that SHP-1 is activated in the course of mitogenic signal transduction in a Ras-dependent manner and that its activity is necessary for the Ras-dependent activation of the MAPK pathway but not of the Raf-1 kinase. Consistent with a role for SHP-1 as an intermediate between Ras and the MEK-MAPK pathway, Ras-independent activation of the latter kinases by bacterial lipopolysaccharide occurred normally in me(v)/me(v) cells. Our results sharply accentuate the diversity of signal transduction in mammalian cells, in which the same signaling intermediates can be rearranged to form different pathways.

scholarly journals Kinase Suppressor of Ras (KSR) Is a Scaffold Which Facilitates Mitogen-Activated Protein Kinase Activation In Vivo

2002 ◽  
Vol 22 (9) ◽  
pp. 3035-3045 ◽  
Author(s):  
AnhCo Nguyen ◽  
W. Richard Burack ◽  
Jeffrey L. Stock ◽  
Robert Kortum ◽  
Oleg V. Chaika ◽  
...  
Keyword(s):  
Protein Kinase ◽  
T Cell Activation ◽  
Mapk Pathway ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Kinase Activation ◽  
Exact Function ◽  
Kinase Suppressor Of Ras ◽  
Mitogen Activated Protein ◽  
Deficient Mice

ABSTRACT While scaffold proteins are thought to be key components of signaling pathways, their exact function is unknown. By preassembling multiple components of signaling cascades, scaffolds are predicted to influence the efficiency and/or specificity of signaling events. Here we analyze a potential scaffold of the Ras/mitogen-activated protein kinase (MAPK) pathway, kinase suppressor of Ras (KSR), by generating KSR-deficient mice. KSR-deficient mice were grossly normal even though ERK kinase activation was attenuated to a degree sufficient to block T-cell activation and inhibit tumor development. Consistent with its role as a scaffold, high-molecular-weight complexes containing KSR, MEK, and ERK were lost in the absence of KSR. This demonstrates that KSR is a bona fide scaffold that is not required for but enhances signaling via the Ras/MAPK signaling pathway.

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