scholarly journals Gαq binds to p110α/p85α phosphoinositide 3-kinase and displaces Ras

2006 ◽  
Vol 394 (3) ◽  
pp. 557-562 ◽  
Author(s):  
Lisa M. Ballou ◽  
Mohar Chattopadhyay ◽  
Yan Li ◽  
Suzanne Scarlata ◽  
Richard Z. Lin
Keyword(s):  
Fluorescence Spectroscopy ◽  
Cell Types ◽  
Binding Domain ◽  
Mitogen Activated Protein Kinase ◽  
Dependent Manner ◽  
Ras Activation ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Phosphoinositide 3 Kinase ◽  
Co Precipitation

Several studies have reported that activation of Gq-coupled receptors inhibits PI3K (phosphoinositide 3-kinase) signalling. In the present study, we used purified proteins to demonstrate that Gαq directly inhibits p110α/p85α PI3K in a GTP-dependent manner. Activated Gαq binds to the p110α/p85α PI3K with an apparent affinity that is seven times stronger than that for Gαq·GDP as measured by fluorescence spectroscopy. In contrast, Gαq did not bind to the p110γ PI3K. Fluorescence spectroscopy experiments also showed that Gαq competes with Ras, a PI3K activator, for binding to p110α/p85α. Interestingly, co-precipitation studies using deletion mutants showed that Gαq binds to the p85-binding domain of p110α and not to the Ras-binding domain. Expression of constitutively active GαqQ209L in cells inhibited Ras activation of the PI3K/Akt pathway but had no effect on Ras/Raf/MEK [MAPK (mitogen-activated protein kinase)/ERK (extracellular-signal-regulated kinase) kinase] signalling. These results suggest that activation of Gq-coupled receptors leads to increased binding of Gαq·GTP to some isoforms of PI3K, which might explain why these receptors inhibit this signalling pathway in certain cell types.

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 Insulin stimulation of pyruvate dehydrogenase in adipocytes involves two distinct signalling pathways

2003 ◽  
Vol 369 (2) ◽  
pp. 351-356 ◽  
Author(s):  
Sam A. JOHNSON ◽  
Richard M. DENTON
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Mitogen Activated Protein Kinase ◽  
Signalling Pathways ◽  
Maximal Effect ◽  
Insulin Stimulation ◽  
Rat Adipocytes ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Phosphoinositide 3 Kinase ◽  
Stimulation Of

In isolated rat adipocytes, the insulin stimulation of pyruvate dehydrogenase can be partially inhibited by inhibitors of PI3K (phosphoinositide 3-kinase) and MEK1/2 (mitogen-activated protein kinase/extracellular signal-regulated kinase kinase). In combination, U0126 and wortmannin completely block the insulin stimulation of pyruvate dehydrogenase. It is concluded that the effect of insulin on pyruvate dehydrogenase in rat adipocytes involves two distinct signalling pathways: one is sensitive to wortmannin and the other to U0126. The synthetic phosphoinositolglycan PIG41 can activate pyruvate dehydrogenase but the activation is only approx. 30% of the maximal effect of insulin. This modest activation can be completely blocked by wortmannin alone, suggesting that PIG41 acts through only one of the pathways leading to the activation of pyruvate dehydrogenase.

scholarly journals Collagen/β1 integrin signaling up-regulates the ABCC1/MRP-1 transporter in an ERK/MAPK-dependent manner

2012 ◽  
Vol 23 (17) ◽  
pp. 3473-3484 ◽  
Author(s):  
Mohammed-Amine El Azreq ◽  
Dalila Naci ◽  
Fawzi Aoudjit
Keyword(s):  
Actin Polymerization ◽  
Mitogen Activated Protein Kinase ◽  
Integrin Signaling ◽  
Β1 Integrin ◽  
Dependent Manner ◽  
Expression Levels ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Induced Apoptosis ◽  
And Function

The mechanisms by which β1 integrins regulate chemoresistance of cancer cells are still poorly understood. In this study, we report that collagen/β1 integrin signaling inhibits doxorubicin-induced apoptosis of Jurkat and HSB2 leukemic T-cells by up-regulating the expression and function of the ATP-binding cassette C 1 (ABCC1) transporter, also known as multidrug resistance–associated protein 1. We find that collagen but not fibronectin reduces intracellular doxorubicin content and up-regulates the expression levels of ABCC1. Inhibition and knockdown studies show that up-regulation of ABCC1 is necessary for collagen-mediated reduction of intracellular doxorubicin content and collagen-mediated inhibition of doxorubicin-induced apoptosis. We also demonstrate that activation of the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase signaling pathway is involved in collagen-induced reduction of intracellular doxorubicin accumulation, collagen-induced up-regulation of ABCC1 expression levels, and collagen-mediated cell survival. Finally, collagen-mediated up-regulation of ABCC1 expression and function also requires actin polymerization. Taken together, our results indicate for the first time that collagen/β1 integrin/ERK signaling up-regulates the expression and function of ABCC1 and suggest that its activation could represent an important pathway in cancer chemoresistance. Thus simultaneous targeting of collagen/β1 integrin and ABCC1 may be more efficient in preventing drug resistance than targeting each pathway alone.

Regulation of MAP kinase by calcium-sensing receptor in bovine parathyroid and CaR-transfected HEK293 cells

2001 ◽  
Vol 280 (2) ◽  
pp. F291-F302 ◽  
Author(s):  
Olga Kifor ◽  
R. John MacLeod ◽  
Ruben Diaz ◽  
Mei Bai ◽  
Toru Yamaguchi ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Combined Treatment ◽  
Cell Types ◽  
Serine Phosphorylation ◽  
Mitogen Activated Protein Kinase ◽  
Hek293 Cells ◽  
Calcium Sensing ◽  
Cytosolic Phospholipase ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

Regulation of the extracellular signal-regulated kinase 1 and 2 (ERK1/2) pathway by the extracellular calcium (Cao 2+)-sensing receptor (CaR) was investigated in bovine parathyroid and CaR-transfected human embryonic kidney (HEKCaR) cells. Elevating Cao 2+ or adding the selective CaR activator NPS R-467 elicited rapid, dose-dependent phosphorylation of ERK1/2. These phosphorylations were attenuated by pretreatment with pertussis toxin (PTX) or by treatment with the phosphotyrosine kinase (PTK) inhibitors genistein and herbimycin, the phosphatidylinositol-specific phospholipase C (PI-PLC) inhibitor U-73122, or the protein kinase C (PKC) inhibitor GF109203X and were enhanced by the PKC activator phorbol 12-myristate 13-acetate. Combined treatment with PTX and inhibitors of both PKC and PTK nearly abolished high Cao 2+-evoked ERK1/2 activation in HEKCaR cells, demonstrating CaR-mediated coupling via both Gq and Gi. High Cao 2+ increased serine phosphorylation of the 85-kDa cytosolic phospholipase A2(cPLA2) in both parathyroid and HEKCaR cells. The selective mitogen-activated protein kinase (MAPK) inhibitor PD98059 abolished high-Cao 2+-induced ERK1/2 activation and reduced cPLA2 phosphorylation in both cell types, documenting MAPK's role in cPLA2 activation. Thus our data suggest that the CaR activates MAPK through PKC, presumably through Gq/11-mediated activation of PI-PLC, as well as through Gi- and PTK-dependent pathway(s) in bovine parathyroid and HEKCaR cells and indicate the importance of MAPK in cPLA2 activation.

scholarly journals Anthrax Lethal Toxin Impairs CD1d-Mediated Antigen Presentation by Targeting the Extracellular Signal-Related Kinase 1/2 Mitogen-Activated Protein Kinase Pathway

2010 ◽  
Vol 78 (5) ◽  
pp. 1859-1863 ◽  
Author(s):  
Masood A. Khan ◽  
Richard M. Gallo ◽  
Randy R. Brutkiewicz
Keyword(s):  
Immune System ◽  
Protein Kinase ◽  
Bacillus Anthracis ◽  
Antigen Presentation ◽  
Specific Inhibitor ◽  
Lethal Toxin ◽  
Mitogen Activated Protein Kinase ◽  
Dependent Manner ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

ABSTRACT Lethal toxin (LT) is a critical virulence factor of Bacillus anthracis and an important means by which this bacterium evades the host's immune system. In this study, we demonstrate that CD1d-expressing cells treated with LT have reduced CD1d-mediated antigen presentation. We earlier showed an important role for the mitogen-activated protein kinase extracellular signal-regulated kinase 1/2 (ERK1/2) in the regulation of CD1d-mediated antigen presentation, and we report here that LT impairs antigen presentation by CD1d in an ERK1/2-dependent manner. Similarly, LT and the ERK1/2 pathway-specific inhibitor U0126 caused a decrease in major histocompatibility complex (MHC) class II-mediated antigen presentation. Confocal microscopy analyses revealed altered intracellular distribution of CD1d and LAMP-1 in LT-treated cells, similar to the case for ERK1/2-inhibited cells. These results suggest that Bacillus anthracis has the ability to evade the host's innate immune system by reducing CD1d-mediated antigen presentation through targeting the ERK1/2 pathway.

scholarly journals p38α Mitogen-activated Protein Kinase Sensitizes Cells to Apoptosis Induced by Different Stimuli

2004 ◽  
Vol 15 (2) ◽  
pp. 922-933 ◽  
Author(s):  
Almudena Porras ◽  
Susana Zuluaga ◽  
Emma Black ◽  
Amparo Valladares ◽  
Alberto M. Alvarez ◽  
...  
Keyword(s):  
Map Kinase ◽  
Cell Types ◽  
Mitogen Activated Protein Kinase ◽  
Extracellular Signal Regulated Kinase ◽  
Survival Pathways ◽  
Proapoptotic Protein ◽  
Extracellular Signal ◽  
Survival Pathway ◽  
Mitogen Activated Protein

p38α mitogen-activated protein (MAP) kinase is a broadly expressed signaling molecule that participates in the regulation of cellular responses to stress as well as in the control of proliferation and survival of many cell types. We have used cell lines derived from p38α knockout mice to study the role of this signaling pathway in the regulation of apoptosis. Here, we show that cardiomyocytes and fibroblasts lacking p38α are more resistant to apoptosis induced by different stimuli. The reduced apoptosis of p38α-deficient cells correlates with decreased expression of the mitochondrial proapoptotic protein Bax and the apoptosis-inducing receptor Fas/CD-95. Cells lacking p38α also have increased extracellular signal-regulated kinase (ERKs) MAP kinase activity, and the up-regulation of this survival pathway seems to be at least partially responsible for the reduced levels of apoptosis in the absence of p38α. Phosphorylation of the transcription factor STAT3 on Ser-727, mediated by the extracellular signal-regulated kinase MAP kinase pathway, may contribute to the decrease in both Bax and Fas expression in p38α-/- cells. Thus, p38α seems to sensitize cells to apoptosis via both up-regulation of proapoptotic proteins and down-regulation of survival pathways.

scholarly journals The Anti-Inflammatory Effects of Shinbaro3 Is Mediated by Downregulation of the TLR4 Signalling Pathway in LPS-Stimulated RAW 264.7 Macrophages

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Hwa-Jin Chung ◽  
Wonil Koh ◽  
Won Kyung Kim ◽  
Joon-Shik Shin ◽  
Jinho Lee ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Raw 264.7 Cells ◽  
Raw 264.7 ◽  
Dependent Manner ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Raw 264.7 Macrophage Cells ◽  
Anti Inflammatory ◽  
Dose Dependent

Shinbaro3, a formulation derived from the hydrolysed roots of Harpagophytum procumbens var. sublobatum (Engl.) Stapf, has been clinically used in the pharamacopuncture treatment of arthritis in Korea. In the present study, Shinbaro3 inhibited NO generation in LPS-induced RAW 264.7 cells in a dose-dependent manner. Shinbaro3 also downregulated the mRNA and protein expression of inflammatory mediators in a dose-dependent manner. Three mechanisms explaining the effects of Shinbaro3 in RAW 264.7 cells were identified as follows: (1) inhibition of the extracellular signal-regulated kinase 1 and 2 (ERK1/2), stress-activated protein kinase (SAPK)/c-Jun N-terminal protein kinase (JNK), and p38 mitogen-activated protein kinase (MAPK) pathways; (2) suppression of IκB kinase-α/β (IKK-α/β) phosphorylation and nuclear factor-kappa B (NF-κB) subunits in the NF-κB pathway, which are involved in MyD88-dependent signalling; and (3) downregulation of IFN-β mRNA expression via inhibition of interferon regulatory factor 3 (IRF3) and Janus-activated kinase 1 (JAK1)/signal transducer and activator of transcription 1 (STAT1) phosphorylation, which is involved in TRIF-dependent signalling. Shinbaro3 exerted anti-inflammatory effects in LPS-stimulated RAW 264.7 macrophage cells through modulation of the TLR4/MyD88 pathways, suggesting that Shinbaro3 is a novel anti-inflammatory therapeutic candidate in the field of pharmacopuncture.

scholarly journals Deoxynivalenol Induces Inflammation in the Small Intestine of Weaned Rabbits by Activating Mitogen-Activated Protein Kinase Signaling

2021 ◽  
Vol 8 ◽  
Author(s):  
Pengwei Wang ◽  
Libo Huang ◽  
Wanying Yang ◽  
Quancheng Liu ◽  
Fuchang Li ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Intestinal Inflammation ◽  
Nutrient Content ◽  
Mitogen Activated Protein Kinase ◽  
Inflammatory Factors ◽  
Dependent Manner ◽  
Feeding Period ◽  
Hematopoietic Cell Kinase ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

Deoxynivalenol (DON) can activate related signaling pathways and induce gastrointestinal disorders. Based on the results of previous studies, this study tried to explore the relationship between DON-induced intestinal inflammation of weaned rabbits and the ERK-p38 signaling pathway. Forty-five weaned rabbits were divided into three treatments: control, LD and HD group. All rabbits were treated with diet containing a same nutrient content, but animals in the LD and HD groups were additionally administered DON via drinking water at 0.5 and 1.5 mg/kg b.w./d, respectively. The protocol consisted of a total feeding period of 31 days, including a pre-feeding period of 7 days. Western blotting, qRT-PCR, and immunohistochemistry were applied for analysis the expression of protein and mRNA of extracellular signal-regulated kinase (ERK), p38, double-stranded RNA-activated protein kinase (PKR), and hematopoietic cell kinase (Hck) in the duodenum, jejunum, and ileum of rabbits, as well as the distribution of positive reactants. The results proved that DON intake could enhance the levels of inflammatory factors in serum and damage the intestinal structure barrier of rabbits. Meanwhile, DON addition can stimulate the protein and mRNA expression for ERK, p38, PKR, and Hck in the intestine of rabbits, especially in the duodenum, as well as expand the distribution of positive reactants, in a dose-dependent manner.

scholarly journals FOXO Transcription Factors: Their Clinical Significance and Regulation

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Yu Wang ◽  
Yanmin Zhou ◽  
Dana T. Graves
Keyword(s):  
Transcription Factors ◽  
Cellular Proliferation ◽  
Cell Types ◽  
Mitogen Activated Protein Kinase ◽  
Survival Pathways ◽  
Mitogen Activated Protein ◽  
Foxo Transcription Factors ◽  
Phosphoinositide 3 Kinase ◽  
Clinical Conditions

Members of the class O of forkhead box transcription factors (FOXO) have important roles in metabolism, cellular proliferation, stress resistance, and apoptosis. The activity of FOXOs is tightly regulated by posttranslational modification, including phosphorylation, acetylation, and ubiquitylation. Activation of cell survival pathways such as phosphoinositide-3-kinase/AKT/IKK or RAS/mitogen-activated protein kinase phosphorylates FOXOs at different sites which regulate FOXOs nuclear localization or degradation. FOXO transcription factors are upregulated in a number of cell types including hepatocytes, fibroblasts, osteoblasts, keratinocytes, endothelial cells, pericytes, and cardiac myocytes. They are involved in a number of pathologic and physiologic processes that include proliferation, apoptosis, autophagy, metabolism, inflammation, cytokine expression, immunity, differentiation, and resistance to oxidative stress. These processes impact a number of clinical conditions such as carcinogenesis, diabetes, diabetic complications, cardiovascular disease, host response, and wound healing. In this paper, we focus on the potential role of FOXOs in different disease models and the regulation of FOXOs by various stimuli.

Sign in / Sign up

Export Citation Format

Share Document