scholarly journals The K5 Capsule of Escherichia coli Strain Nissle 1917 Is Important in Stimulating Expression of Toll-Like Receptor 5, CD14, MyD88, and TRIF Together with the Induction of Interleukin-8 Expression via the Mitogen-Activated Protein Kinase Pathway in Epithelial Cells

2010 ◽  
Vol 78 (5) ◽  
pp. 2153-2162 ◽  
Author(s):  
Mohamed Hafez ◽  
Kelly Hayes ◽  
Marie Goldrick ◽  
Richard K. Grencis ◽  
Ian S. Roberts
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Map Kinase ◽  
Interleukin 8 ◽  
Mitogen Activated Protein Kinase ◽  
Probiotic Properties ◽  
Toll Like Receptor ◽  
Mitogen Activated Protein ◽  
Map Kinase Pathway ◽  
Kinase Pathway

ABSTRACT Escherichia coli strain Nissle 1917, which has been widely used as a probiotic for the treatment of inflammatory bowel disorders, expresses a K5 capsule, the expression of which is often associated with extraintestinal and urinary tract isolates of E. coli. Previously, it had been shown that the expression of a K5 capsule by Nissle 1917 was important in mediating interactions with epithelial cells and the extent of chemokine expression. In this paper, we show that infection with Nissle 1917 induces expression of Toll-like receptor 4 (TLR4) and TLR5 in Caco-2 cells and that maximal induction of TLR5 required the K5 capsule. In addition, purified K5 polysaccharide was capable of inducing expression of TLR5 and mCD14 and potentiated the activity of both TLR4 and TLR5 agonists to increase the proinflammatory response. Infection with Nissle 1917 also increased the expression of the adaptor molecules MyD88 and TRIF, which was K5 capsule dependent. By Western blot analysis, it was possible to show that induction of interleukin-8 by Nissle 1917 was predominantly through the mitogen-activated protein (MAP) kinase pathway and that expression of the K5 capsule was important for activation of the MAP kinase pathway. This paper provides new information on the function of the K5 capsule in mediating interactions between Nissle 1917 and epithelial cells and the mechanisms that underlie the probiotic properties of Nissle 1917.

scholarly journals Differential regulation of Raf-1 and B-Raf and Ras-dependent activation of mitogen-activated protein kinase by cyclic AMP in PC12 cells.

1995 ◽  
Vol 15 (10) ◽  
pp. 5524-5530 ◽  
Author(s):  
P Erhardt ◽  
J Troppmair ◽  
U R Rapp ◽  
G M Cooper
Keyword(s):  
Growth Factor ◽  
Cyclic Amp ◽  
Map Kinase ◽  
Pc12 Cells ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Mitogen Activated Protein ◽  
Map Kinase Pathway ◽  
Kinase Pathway ◽  
Stimulation Of

Growth factor stimulation of the mitogen-activated protein (MAP) kinase pathway in fibroblasts is inhibited by cyclic AMP (cAMP) as a result of inhibition of Raf-1. In contrast, cAMP inhibits neither nerve growth factor-induced MAP kinase activation nor differentiation in PC12 pheochromocytoma cells. Instead, in PC12 cells cAMP activates MAP kinase. Since one of the major differences between the Ras/Raf/MAP kinase cascades of these cell types is the expression of B-Raf in PC12 cells, we compared the effects of cAMP on Raf-1 and B-Raf. In PC12 cells maintained in serum-containing medium, B-Raf was refractory to inhibition by cAMP, whereas Raf-1 was effectively inhibited. In contrast, both B-Raf and Raf-1 were inhibited by cAMP in serum-starved PC12 cells. The effect of cAMP is thus dependent upon growth conditions, with B-Raf being resistant to cAMP inhibition in the presence of serum. These results were extended by studies of Rat-1 fibroblasts into which B-Raf had been introduced by transfection. As in PC12 cells, B-Raf was resistant to inhibition by cAMP in the presence of serum, whereas Raf-1 was effectively inhibited. In addition, the expression of B-Raf rendered Rat-1 cells resistant to the inhibitory effects of cAMP on both growth factor-induced activation of MAP kinase and mitogenesis. These results indicate that Raf-1 and B-Raf are differentially sensitive to inhibition by cAMP and that B-Raf expression can contribute to cell type-specific differences in the regulation of the MAP kinase pathway. In contrast to the situation in PC12 cells, cAMP by itself did not stimulate MAP kinase in B-Raf-expressing Rat-1 cells. The activation of MAP kinase by cAMP in PC12 cells was inhibited by the expression of a dominant negative Ras mutant, indicating that cAMP acts on a target upstream of Ras. Thus, it appears that a signaling component upstream of Ras is also require for cAMP stimulation of MAP kinase in PC12 cells.

scholarly journals ras2 Controls Morphogenesis, Pheromone Response, and Pathogenicity in the Fungal Pathogen Ustilago maydis

2002 ◽  
Vol 1 (6) ◽  
pp. 954-966 ◽  
Author(s):  
Nancy Lee ◽  
James W. Kronstad
Keyword(s):  
Protein Kinase ◽  
Map Kinase ◽  
Ustilago Maydis ◽  
Mitogen Activated Protein Kinase ◽  
Gene Encoding ◽  
Mitogen Activated Protein ◽  
Kinase Cascade ◽  
Map Kinase Pathway ◽  
Altered Cell ◽  
Kinase Pathway

ABSTRACT Ustilago maydis, a pathogen of maize, is a useful model for the analysis of mating, pathogenicity, and the morphological transition between budding and filamentous growth in fungi. As in other fungi, these processes are regulated by conserved signaling mechanisms, including the cyclic AMP (cAMP)/protein kinase A (PKA) pathway and at least one mitogen-activated protein kinase (MAP kinase) pathway. A current challenge is to identify additional factors that lie downstream of the cAMP pathway and that influence morphogenesis in U. maydis. In this study, we identified suppressor mutations that restored budding growth to a constitutively filamentous mutant with a defect in the gene encoding a catalytic subunit of PKA. Complementation of one suppressor mutation unexpectedly identified the ras2 gene, which is predicted to encode a member of the well-conserved ras family of small GTP-binding proteins. Deletion of the ras2 gene in haploid cells altered cell morphology, eliminated pathogenicity on maize seedlings, and revealed a role in the production of aerial hyphae during mating. We also used an activated ras2 allele to demonstrate that Ras2 promotes pseudohyphal growth via a MAP kinase cascade involving the MAP kinase kinase Fuz7 and the MAP kinase Ubc3. Overall, our results reveal an additional level of crosstalk between the cAMP signaling pathway and a MAP kinase pathway influenced by Ras2.

scholarly journals A Mitogen-Activated Protein Kinase That Senses Nitrogen Regulates Conidial Germination and Growth in Aspergillus fumigatus

2004 ◽  
Vol 3 (2) ◽  
pp. 557-560 ◽  
Author(s):  
Tao Xue ◽  
C. Kim Nguyen ◽  
Angela Romans ◽  
Gregory S. May
Keyword(s):  
Protein Kinase ◽  
Aspergillus Fumigatus ◽  
Map Kinase ◽  
Conidial Germination ◽  
Mitogen Activated Protein Kinase ◽  
Protein Map ◽  
Mitogen Activated Protein ◽  
Map Kinase Pathway ◽  
Germination And Growth ◽  
Kinase Pathway

ABSTRACT We show that the mitogen-activated protein (MAP) kinase pathway that responds to osmotic stress in Aspergillus fumigatus is also involved in nutritional sensing. This MAP kinase regulates conidial germination in response to the nitrogen source and is activated upon starvation for either carbon or nitrogen during vegetative growth.

scholarly journals MEK Inhibition Suppresses Growth of Atypical Teratoid/Rhabdoid Tumors

2020 ◽  
Vol 79 (7) ◽  
pp. 746-753
Author(s):  
Shubin Shahab ◽  
Jeffrey Rubens ◽  
Harpreet Kaur ◽  
Heather Sweeney ◽  
Charles G Eberhart ◽  
...  
Keyword(s):  
Map Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Low Grade ◽  
Mitogen Activated Protein ◽  
Atypical Teratoid ◽  
Map Kinase Pathway ◽  
Rhabdoid Tumors ◽  
Pathway Inhibition ◽  
Induced Apoptosis ◽  
Kinase Pathway

Abstract Atypical teratoid/rhabdoid (AT/RT) tumors are the most common malignant brain tumor of infancy and have a poor prognosis. We have previously identified very high expression of LIN28A and/or LIN28B in AT/RT tumors and showed that AT/RT have corresponding increased expression of the mitogen-activated protein (MAP) kinase pathway. Binimetinib is a novel inhibitor of mitogen-activated protein kinase (MAP2K1 or MEK), and is currently in pediatric phase II clinical trials for low-grade glioma. We hypothesized that binimetinib would inhibit growth of AT/RT cells by suppressing the MAP kinase pathway. Binimetinib inhibited AT/RT growth at nanomolar concentrations. Binimetinib decreased cell proliferation and induced apoptosis in AT/RT cells and significantly reduced AT/RT tumor growth in flank xenografts. Our data suggest that MAP kinase pathway inhibition could offer a potential avenue for treating these highly aggressive tumors.

scholarly journals Saccharomyces boulardii Preserves the Barrier Function and Modulates the Signal Transduction Pathway Induced in Enteropathogenic Escherichia coli-Infected T84 Cells

2000 ◽  
Vol 68 (10) ◽  
pp. 5998-6004 ◽  
Author(s):  
Dorota Czerucka ◽  
Stephanie Dahan ◽  
Baharia Mograbi ◽  
Bernard Rossi ◽  
Patrick Rampal
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Signal Transduction Pathway ◽  
Specific Inhibitor ◽  
Saccharomyces Boulardii ◽  
Intracellular Bacteria ◽  
T84 Cells ◽  
Protein Map ◽  
Mitogen Activated Protein ◽  
Map Kinase Pathway

ABSTRACT Use of the nonpathogenic yeast Saccharomyces boulardiiin the treatment of infectious diarrhea has attracted growing interest. The present study designed to investigate the effect of this yeast on enteropathogenic Escherichia coli (EPEC)-associated disease demonstrates that S. boulardii abrogated the alterations induced by an EPEC strain on transepithelial resistance, [3H]inulin flux, and ZO-1 distribution in T84 cells. Moreover, EPEC-mediated apoptosis of epithelial cells was delayed in the presence of S. boulardii. The yeast did not modify the number of adherent bacteria but lowered by 50% the number of intracellular bacteria. Infection by EPEC induced tyrosine phosphorylation of several proteins in T84 cells, including p46 and p52 SHC isoforms, that was attenuated in the presence of S. boulardii. Similarly, EPEC-induced activation of the ERK1/2 mitogen-activated protein (MAP) kinase pathway was diminished in the presence of the yeast. Interestingly, inhibition of the ERK1/2 pathway with the specific inhibitor PD 98059 decreased EPEC internalization, suggesting that modulation of the ERK1/2 MAP pathway might account for the lowering of the number of intracellular bacteria observed in the presence of S. boulardii. Altogether, this study demonstrated that S. boulardii exerts a protective effect on epithelial cells after EPEC adhesion by modulating the signaling pathway induced by bacterial infection.

scholarly journals Role of Mitogen-Activated Protein Kinase Pathway in Prostaglandin F2α-Induced Rat Puerperal Uterine Contraction

Endocrinology ◽  
1997 ◽  
Vol 138 (8) ◽  
pp. 3103-3111 ◽  
Author(s):  
Masahide Ohmichi ◽  
Koji Koike ◽  
Akiko Kimura ◽  
Kanji Masuhara ◽  
Hiromasa Ikegami ◽  
...  
Keyword(s):  
Map Kinase ◽  
Uterine Contraction ◽  
Prostaglandin F2α ◽  
Mek Inhibitor ◽  
Biological Action ◽  
Mitogen Activated Protein Kinase ◽  
Myometrial Cells ◽  
Mitogen Activated Protein ◽  
Kinase Pathway

Abstract In this study, prostaglandin (PG) F2α was found to activate mitogen-activated protein (MAP) kinase and MAP kinase kinase (MEK) in cultured rat puerperal uterine myometrial cells. PGF2α stimulation also led to an increase in phosphorylation of raf-1, son of sevenless (SOS), and Shc. Furthermore, we examined the mechanism by which PGF2α induced MAP kinase phosphorylation. Both pertussis toxin (10 ng/ml), which inactivates Gi/Go proteins, and expression of a peptide derived from the carboxyl terminus of the β-adrenergic receptor kinase 1 (βARK1), which specifically blocks signaling mediated by the βγ subunits of G proteins, blocked the PGF2α-induced activation of MAP kinase. Ritodrine (1 μm), which is known to relax uterine muscle contraction, attenuated PGF2α-induced tyrosine phosphorylation of MAP kinase. Moreover, to examine the role of MAP kinase pathway in uterine contraction, an inhibitor of MEK activity, PD098059, was used. Although MEK inhibitor had no effect on PGF2α-induced calcium mobilization, this inhibitor partially inhibited PGF2α-induced uterine contraction. These results provide evidence that PGF2α stimulates the MAP kinase signaling pathway in cultured rat puerperal uterine myometrial cells through Gβγ protein, suggesting that this new pathway may play an important role in the biological action of PGF2α on these cells.

scholarly journals Interleukin-8 Regulation of the Ras/Raf/Mitogen-activated Protein Kinase Pathway in Human Neutrophils

1996 ◽  
Vol 271 (5) ◽  
pp. 2832-2838 ◽  
Author(s):  
Cindy Knall ◽  
Scott Young ◽  
Jerry A. Nick ◽  
Anne Mette Buhl ◽  
G. Scott Worthen ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Interleukin 8 ◽  
Mitogen Activated Protein Kinase ◽  
Human Neutrophils ◽  
Mitogen Activated Protein ◽  
Kinase Pathway

scholarly journals Mitogen-activated protein kinase activation is insufficient for growth factor receptor-mediated PC12 cell differentiation.

1995 ◽  
Vol 15 (7) ◽  
pp. 3644-3653 ◽  
Author(s):  
R R Vaillancourt ◽  
L E Heasley ◽  
J Zamarripa ◽  
B Storey ◽  
M Valius ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Growth Factor ◽  
Map Kinase ◽  
Pc12 Cells ◽  
Pc12 Cell ◽  
Growth Factor Receptor ◽  
Receptor Activation ◽  
Mitogen Activated Protein ◽  
Map Kinase Pathway ◽  
Kinase Pathway

When expressed in PC12 cells, the platelet-derived growth factor beta receptor (beta PDGF-R) mediates cell differentiation. Mutational analysis of the beta PDGF-R indicated that persistent receptor stimulation of the Ras/Raf/mitogen-activated protein (MAP) kinase pathway alone was insufficient to sustain PC12 cell differentiation. PDGF receptor activation of signal pathways involving p60c-src or the persistent regulation of phospholipase C gamma was required for PC12 cell differentiation. beta PDGF-R regulation of phosphatidylinositol 3-kinase, the GTPase-activating protein of Ras, and the tyrosine phosphatase, Syp, was not required for PC12 cell differentiation. In contrast to overexpression of oncoproteins involved in regulating the MAP kinase pathway, growth factor receptor-mediated differentiation of PC12 cells requires the integration of other signals with the Ras/Raf/MAP kinase pathway.

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