scholarly journals IQGAP1 Is a Scaffold for Mitogen-Activated Protein Kinase Signaling

2005 ◽  
Vol 25 (18) ◽  
pp. 7940-7952 ◽  
Author(s):  
Monideepa Roy ◽  
Zhigang Li ◽  
David B. Sacks
Keyword(s):  
Growth Factor ◽  
Map Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Kinase Signaling ◽  
Cellular Functions ◽  
Molecular Scaffold ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Erk Activity

ABSTRACT IQGAP1 modulates many cellular functions such as cell-cell adhesion, transcription, cytoskeletal architecture, and selected signaling pathways. We previously documented that IQGAP1 binds extracellular signal-regulated kinase (ERK) 2 and regulates growth factor-stimulated ERK activity. Here we show that MEK, the molecule immediately upstream of ERK in the Ras/mitogen-activated protein (MAP) kinase signaling cascade, also interacts directly with IQGAP1. Both MEK1 and MEK2 bound IQGAP1 in vitro and coimmunoprecipitated with IQGAP1. The addition of ERK2 enhanced by fourfold the in vitro interaction of MEK2 with IQGAP1 without altering binding of MEK1. Similarly, ERK1 promoted MEK binding to IQGAP1, but either MEK protein altered the association between IQGAP1 and ERK. Epidermal growth factor (EGF) differentially regulated binding, enhancing MEK1 interaction while reducing MEK2 binding to IQGAP1. In addition, both knockdown and overexpression of IQGAP1 reduced EGF-stimulated activation of MEK and ERK. Analyses with selective IQGAP1 mutant constructs indicated that MEK binding is crucial for IQGAP1 to modulate EGF activation of ERK. Our data strongly suggest that IQGAP1 functions as a molecular scaffold in the Ras/MAP kinase pathway.

α1-Adrenergic activation of myocardial Na-K-2Cl cotransport involving mitogen-activated protein kinase

1998 ◽  
Vol 275 (2) ◽  
pp. H641-H652 ◽  
Author(s):  
Geir Øystein Andersen ◽  
Mette Enger ◽  
G. Hege Thoresen ◽  
Tor Skomedal ◽  
Jan-Bjørn Osnes
Keyword(s):  
Protein Kinase ◽  
Map Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Extracellular Signal ◽  
Rat Hearts ◽  
Protein Map ◽  
Mitogen Activated Protein ◽  
Β Blocker ◽  
Map Kinase Pathway ◽  
Erk Activity

The translocation mechanisms involved in the α1-adrenoceptor-stimulated efflux of the potassium analog86Rb+were studied in isolated rat hearts. Phenylephrine (in the presence of a β-blocker) increased the efflux of86Rb+and42K+, and the Na-K-2Cl (or K-Cl) cotransport inhibitor bumetanide reduced the response by 42 ± 11%. Furosemide inhibited the response with a lower potency than that of bumetanide. The bumetanide-insensitive efflux was largely sensitive to the K+ channel inhibitor 4-aminopyridine. Inhibitors of the Na+/H+exchanger or the Na+-K+pump had no effect on the increased86Rb+efflux. The activation of the Na-K-2Cl cotransporter was dependent on the extracellular signal-regulated kinase (ERK) subgroup of the mitogen-activated protein (MAP) kinase family. Phenylephrine stimulation increased ERK activity 3.4-fold. PD-98059, an inhibitor of the ERK cascade, reduced both the increased86Rb+efflux and ERK activity. Specific inhibitors of protein kinase C and Ca2+/calmodulin-dependent kinase II had no effect. In conclusion, α1-adrenoceptor stimulation increases86Rb+efflux from the rat heart via K+channels and a Na-K-2Cl cotransporter. Activation of the Na-K-2Cl cotransporter is apparently dependent on the MAP kinase pathway.

scholarly journals Cyclic AMP Selectively Uncouples Mitogen-Activated Protein Kinase Cascades from Activating Signals

2006 ◽  
Vol 26 (8) ◽  
pp. 3039-3047 ◽  
Author(s):  
Gray W. Pearson ◽  
Svetlana Earnest ◽  
Melanie H. Cobb
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Map Kinase ◽  
Signaling Pathways ◽  
Cellular Response ◽  
Mitogen Activated Protein Kinase ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

ABSTRACT Cells integrate signals to select the appropriate response from an array of possible outcomes. Signal integration causes the reorganization of signaling pathways by undescribed events. To analyze the molecular changes in signaling pathways that elicit different responses, we focused on the interaction between cyclic AMP (cAMP) and growth factors. We show that the activation of extracellular signal-regulated kinase 5 (ERK5), but not ERK1/2, by growth factors is disrupted by cAMP through cAMP-dependent protein kinase (PKA). Activation of MEKK2, a mitogen-activated protein (MAP) kinase kinase kinase upstream of ERK5 that is required for growth factor activation of ERK5, is also disrupted by PKA. Transcription of c-Jun is induced by ERK5, and like ERK5, c-Jun induction is also blocked by cAMP. Transcription from the serum response element, like activation of ERK1/2, is not blocked by cAMP. Collectively, these results support a model in which cAMP shapes the growth factor-induced cellular response through PKA-dependent uncoupling of selected MAP kinase cascades from activating signals.

scholarly journals Integrin αvβ3 Requirement for Sustained Mitogen-activated Protein Kinase Activity during Angiogenesis

1998 ◽  
Vol 140 (5) ◽  
pp. 1255-1263 ◽  
Author(s):  
Brian P. Eliceiri ◽  
Richard Klemke ◽  
Staffan Strömblad ◽  
David A. Cheresh
Keyword(s):  
Endothelial Cells ◽  
Growth Factors ◽  
Growth Factor ◽  
Map Kinase ◽  
Blood Vessels ◽  
Integrin Αvβ3 ◽  
Protein Kinase Activity ◽  
Mitogen Activated Protein ◽  
Erk Activity

Angiogenesis depends on growth factors and vascular cell adhesion events. Integrins and growth factors are capable of activating the ras/MAP kinase pathway in vitro, yet how these signals influence endothelial cells during angiogenesis is unknown. Upon initiation of angiogenesis with basic fibroblast growth factor (bFGF) on the chick chorioallantoic membrane (CAM), endothelial cell mitogen-activated protein (MAP) kinase (ERK) activity was detected as early as 5 min yet was sustained for at least 20 h. The initial wave of ERK activity (5–120 min) was refractory to integrin antagonists, whereas the sustained activity (4–20 h) depended on integrin αvβ3, but not β1 integrins. Inhibition of MAP kinase kinase (MEK) during this sustained αvβ3-dependent ERK signal blocked the formation of new blood vessels while not influencing preexisting blood vessels on the CAM. Inhibition of MEK also blocked growth factor induced migration but not adhesion of endothelial cells in vitro. Therefore, angiogenesis depends on sustained ERK activity regulated by the ligation state of both a growth factor receptor and integrin αvβ3.

Involvement of Ras/MAP Kinase in the Regulation of Ca2+ Channels in Adult Bullfrog Sympathetic Neurons by Nerve Growth Factor

1998 ◽  
Vol 80 (3) ◽  
pp. 1352-1361 ◽  
Author(s):  
Saobo Lei ◽  
William F. Dryden ◽  
Peter A. Smith
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Protein Kinase ◽  
Map Kinase ◽  
Kinase Inhibitors ◽  
Sympathetic Neurons ◽  
Mitogen Activated Protein Kinase ◽  
Nerve Growth ◽  
Channel Current ◽  
Mitogen Activated Protein

Lei, Saobo, William F. Dryden, and Peter A. Smith. Involvement of Ras/MAP kinase in the regulation of Ca2+ channels in adult bullfrog sympathetic neurons by nerve growth factor. J. Neurophysiol. 80: 1352–1361, 1998. The cellular mechanisms that underlie nerve growth factor (NGF) induced increase in Ca2+-channel current in adult bullfrog sympathetic B-neurons were examined by whole cell recording techniques. Cells were maintained at low density in neuron-enriched, defined-medium, serum-free tissue culture for 6 days in the presence or absence of NGF (200 ng/ml). The increase in Ba2+ current ( I Ba) density induced by NGF was attenuated by the RNA synthesis inhibitor cordycepin (20 μM), by the DNA transcription inhibitor actinomycin D (0.01 μg/ml), by inhibitors of Ras isoprenylation (perillic acid 0.1–1.0 mM or α-hydroxyfarnesylphosphonic acid 10–100 μM), by tyrosine kinase inhibitors genistein (20 μM) or lavendustin A (1 μM), and by PD98059 (10–100 μM), an inhibitor of mitogen-activated protein kinase kinase. Inhibitors of the phosphatidylinositol 3-kinase (PI3K) pathway (wortmannin, 100 nM, or LY29400, 100 μM) were ineffective as were inhibitors of phospholipase Cγ (U73122 or neomycin, both 100 μM). The effect of NGF persisted in Ca2+-free medium that contained 1.8 mM Mg2+ and 2 mM ethylene glycol-bis(β-aminoethyl ether)- N, N, N′, N′-tetraacetic acid. It was mimicked by a Trk antibody that was capable of inducing neurite outgrowth in explant cultures of bullfrog sympathetic ganglion. Antibodies raised against the low-affinity p75 neurotrophin receptor were ineffective in blocking the effect of NGF on I Ba. These results suggest that NGF-induced increase in Ca2+ channel current in adult sympathetic neurons results, at least in part, from new channel synthesis after Trk activation of Ras and mitogen activated protein kinase by a mechanism that is independent of extracellular Ca2+.

scholarly journals Extracellular Signal-Regulated Kinases Phosphorylate Mitogen-Activated Protein Kinase Phosphatase 3/DUSP6 at Serines 159 and 197, Two Sites Critical for Its Proteasomal Degradation

2005 ◽  
Vol 25 (2) ◽  
pp. 854-864 ◽  
Author(s):  
Sandrine Marchetti ◽  
Clotilde Gimond ◽  
Jean-Claude Chambard ◽  
Thomas Touboul ◽  
Danièle Roux ◽  
...  
Keyword(s):  
Map Kinases ◽  
Fluorescent Protein ◽  
Proteasomal Degradation ◽  
Mitogen Activated Protein Kinase ◽  
Dependent Manner ◽  
Double Mutation ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

ABSTRACT Mitogen-activated protein (MAP) kinase phosphatases (MKPs) are dual-specificity phosphatases that dephosphorylate phosphothreonine and phosphotyrosine residues within MAP kinases. Here, we describe a novel posttranslational mechanism for regulating MKP-3/Pyst1/DUSP6, a member of the MKP family that is highly specific for extracellular signal-regulated kinase 1 and 2 (ERK1/2) inactivation. Using a fibroblast model in which the expression of either MKP-3 or a more stable MKP-3-green fluorescent protein (GFP) chimera was induced by tetracycline, we found that serum induces the phosphorylation of MKP-3 and its subsequent degradation by the proteasome in a MEK1 and MEK2 (MEK1/2)-ERK1/2-dependent manner. In vitro phosphorylation assays using glutathione S-transferase (GST)-MKP-3 fusion proteins indicated that ERK2 could phosphorylate MKP-3 on serines 159 and 197. Tetracycline-inducible cell clones expressing either single or double serine mutants of MKP-3 or MKP-3-GFP confirmed that these two sites are targeted by the MEK1/2-ERK1/2 module in vivo. Double serine mutants of MKP-3 or MKP-3-GFP were more efficiently protected from degradation than single mutants or wild-type MKP-3, indicating that phosphorylation of either serine by ERK1/2 enhances proteasomal degradation of MKP-3. Hence, double mutation caused a threefold increase in the half-life of MKP-3. Finally, we show that the phosphorylation of MKP-3 has no effect on its catalytic activity. Thus, ERK1/2 exert a positive feedback loop on their own activity by promoting the degradation of MKP-3, one of their major inactivators in the cytosol, a situation opposite to that described for the nuclear phosphatase MKP-1.

scholarly journals Direct recruitment of CRK and GRB2 to VEGFR-3 induces proliferation, migration, and survival of endothelial cells through the activation of ERK, AKT, and JNK pathways

Blood ◽  
2005 ◽  
Vol 106 (10) ◽  
pp. 3423-3431 ◽  
Author(s):  
Ahmad Salameh ◽  
Federico Galvagni ◽  
Monia Bardelli ◽  
Federico Bussolino ◽  
Salvatore Oliviero
Keyword(s):  
Endothelial Cells ◽  
Growth Factor ◽  
Umbilical Vein ◽  
Growth Factor Receptor ◽  
Mitogen Activated Protein Kinase ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Capillary Plexus ◽  
Primary Capillary Plexus ◽  
Umbilical Vein Endothelial Cells

AbstractVascular endothelial growth factor receptor-3 (VEGFR-3) plays a key role for the remodeling of the primary capillary plexus in the embryo and contributes to angiogenesis and lymphangiogenesis in the adult. However, VEGFR-3 signal transduction pathways remain to be elucidated. Here we investigated VEGFR-3 signaling in primary human umbilical vein endothelial cells (HUVECs) by the systematic mutation of the tyrosine residues potentially involved in VEGFR-3 signaling and identified the tyrosines critical for its function. Y1068 was shown to be essential for the kinase activity of the receptor. Y1063 signals the receptor-mediated survival by recruiting CRKI/II to the activated receptor, inducing a signaling cascade that, via mitogen-activated protein kinase kinase-4 (MKK4), activates c-Jun N-terminal kinase-1/2 (JNK1/2). Inhibition of JNK1/2 function either by specific peptide inhibitor JNKI1 or by RNA interference (RNAi) demonstrated that activation of JNK1/2 is required for a VEGFR-3–dependent prosurvival signaling. Y1230/Y1231 contributes, together with Y1337, to proliferation, migration, and survival of endothelial cells. Phospho-Y1230/Y1231 directly recruits growth factor receptor–bonus protein (GRB2) to the receptor, inducing the activation of both AKT and extracellular signal–related kinase 1/2 (ERK1/2) signaling. Finally, we observed that Y1063 and Y1230/Y1231 signaling converge to induce c-JUN expression, and RNAi experiments demonstrated that c-JUN is required for growth factor–induced prosurvival signaling in primary endothelial cells.

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