scholarly journals Case Report: Opposite Effects of BRAF Inhibition on Closely Related Clonal Myeloid Disorders

2021 ◽  
Vol 11 ◽  
Author(s):  
Katrin E. Hostettler ◽  
Elisa Casañas Quintana ◽  
Michael Tamm ◽  
Spasenija Savic Prince ◽  
Gregor Sommer ◽  
...  
Keyword(s):  
Map Kinase ◽  
Braf V600e ◽  
Driver Mutations ◽  
Loss Of Function ◽  
Hematopoietic Stem ◽  
Unknown Significance ◽  
Mitogen Activated Protein ◽  
Patients At Risk ◽  
Map Kinase Pathway ◽  
Kinase Pathway

Langerhans cell histiocytosis (LCH) commonly co-occurs with additional myeloid malignancies. The introduction of targeted therapies, blocking “driver” mutations (e.g., BRAF V600E), enabled long-term remission in patients with LCH. The effect of BRAF inhibition on the course and the prognosis of co-existing clonal hematopoiesis is poorly understood. We report on a 61-year-old patient with systemic BRAF V600E positive LCH and concomitant BRAF wild-type (wt) clonal cytopenia of unknown significance (CCUS) with unfavorable somatic mutations including loss of function (LOF) of NF1. While manifestations of LCH improved after blocking BRAF by dabrafenib treatment, the BRAF wt CCUS progressed to acute myeloid leukemia (AML). The patient eventually underwent successful allogeneic hematopoietic stem cell transplantation (HSCT). We performed an in-depth analyzes of the clonal relationship of CCUS and the tissue affected by LCH by using next-generation sequencing (NGS). The findings suggest activation of the mitogen-activated protein (MAP) kinase pathway in the CCUS clone due to the presence of the RAS deregulating NF1 mutations and wt BRAF, which is reportedly associated with paradoxical activation of CRAF and hence MEK. Patients with LCH should be carefully screened for potential additional clonal hematological diseases. NGS can help predict outcome of the latter in case of BRAF inhibition. Blocking the MAP kinase pathway further downstream (e.g., by using MEK inhibitors) or allogeneic HSCT may be options for patients at risk.

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.

Dibucaine and Tetracaine Inhibit the Activation of Mitogen-activated Protein Kinase Mediated by L-type Calcium Channels in PC12 Cells 

1999 ◽  
Vol 91 (6) ◽  
pp. 1798-1798 ◽  
Author(s):  
Masumi Kansha ◽  
Taro Nagata ◽  
Kazuo Irita ◽  
Shosuke Takahashi
Keyword(s):  
Map Kinase ◽  
Pc12 Cells ◽  
Local Anesthetics ◽  
Mitogen Activated Protein ◽  
Ic50 Values ◽  
Map Kinase Pathway ◽  
Kinase Signaling Pathway ◽  
Kinase Pathway ◽  
Map Kinase Signaling Pathway ◽  
Ca2 Channels

Background An elevation of the intracellular calcium level, which is mediated by N-methyl-D-aspartate receptors and L-type Ca2+ channels both, activates the mitogen-activated protein (MAP) kinase signaling pathway involved in synaptic modification. It has recently been suggested that MAP kinase plays a role in coupling the synaptic excitation to gene expression in the nucleus of postsynaptic neurons. Because the effects of local anesthetics on cellular signal transduction in neuronal cells are not well-known, the authors investigated whether they affect the MAP kinase signaling pathway using PC12 cells. Methods The cells were stimulated with either 50 mM KCl or 1 microM ionomycin, and activated MAP kinase was thus immunoprecipitated. The immunocomplexes were then subjected to an Elk1 phosphorylation assay. Both the phosphorylation of MAP kinase and the induction of c-Fos were detected by immunoblotting. Results Pretreatment of the cells with 1 mM (ethylenedioxy)-diethyl-enedinitrilotetraacetic acid or 5 micron nifedipine blocked the MAP kinase activation induced by 50 mM KCl, whereas pretreatment with 2 microM omega-conotoxin GIVA did not. The expression of c-Fos induced by potassium chloride was also suppressed by dibucaine, tetracaine (concentrations that inhibited 50% of the activity of positive control [IC50s] were 16.2+/-0.2 and 73.2+/-0.7 microM, respectively), and PD 98059, a mitogen-activated/extracellular receptor-regulated kinase inhibitor. Higher concentrations of dibucaine and tetracaine were needed to suppress the activation of MAP kinase induced by ionomycin (the IC50 values of dibucaine and tetracaine were 62.5+/-2.2 and 330.5+/-32.8 microM, respectively) compared with potassium chloride (the IC50 values of dibucaine and tetracaine were 17.7+/-1.0 and 70.2+/-1.2 microM, respectively). Although probable targets of these local anesthetics might be L-type Ca2+ channels or components between Ca2+ and Ras in MAP kinase pathway, the possibility that they directly affect MAP kinase still remains. Conclusions Dibucaine and tetracaine at clinical concentrations were found to inhibit the activation of MAP kinase and the expression of c-Fos mediated by L-type Ca2+ channels in PC12 cells. The suppression of MAP kinase pathway may thus be a potential target site for the actions of dibucaine and tetracaine, including the modification of the synaptic functions.

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.

Inhibition of the p38 MAP kinase pathway destabilizes smooth muscle length during physiological loading

2002 ◽  
Vol 282 (5) ◽  
pp. L1117-L1121 ◽  
Author(s):  
Oren J. Lakser ◽  
Robert P. Lindeman ◽  
Jeffrey J. Fredberg
Keyword(s):  
Smooth Muscle ◽  
Map Kinase ◽  
Muscle Length ◽  
P38 Map Kinase ◽  
Force Fluctuations ◽  
Physiological Loading ◽  
Mitogen Activated Protein ◽  
Equilibrium Length ◽  
Map Kinase Pathway ◽  
Kinase Pathway

We tested the hypothesis that mechanical plasticity of airway smooth muscle may be mediated in part by the p38 mitogen-activated protein (MAP) kinase pathway. Bovine tracheal smooth muscle (TSM) strips were mounted in a muscle bath and set to their optimal length, where the active force was maximal (Fo). Each strip was then contracted isotonically (at 0.32 Fo) with ACh (maintained at 10−4 M) and allowed to shorten for 180 min, by which time shortening was completed and the static equilibrium length was established. To simulate the action of breathing, we then superimposed on this steady distending force a sinusoidal force fluctuation with zero mean, at a frequency of 0.2 Hz, and measured incremental changes in muscle length. We found that TSM strips incubated in 10 μM SB-203580-HCl, an inhibitor of the p38 MAP kinase pathway, demonstrated a greater degree of fluctuation-driven lengthening than did control strips, and upon removal of the force fluctuations they remained at a greater length. We also found that the force fluctuations themselves activated the p38 MAP kinase pathway. These findings are consistent with the hypothesis that inhibition of the p38 MAP kinase pathway destabilizes muscle length during physiological loading.

Erk MAP kinase regulates branching morphogenesis in the developing mouse kidney

Development ◽  
2001 ◽  
Vol 128 (21) ◽  
pp. 4329-4338 ◽  
Author(s):  
Carolyn E. Fisher ◽  
Lydia Michael ◽  
Mark W. Barnett ◽  
Jamie A. Davies
Keyword(s):  
Map Kinase ◽  
Kinase Inhibitor ◽  
Branching Morphogenesis ◽  
Dependent Manner ◽  
Ureteric Bud ◽  
Strong Concentration ◽  
Erk Activation ◽  
Mitogen Activated Protein ◽  
Map Kinase Pathway ◽  
Kinase Pathway

Branching morphogenesis of epithelium is a common and important feature of organogenesis; it is, for example, responsible for development of renal collecting ducts, lung airways, milk ducts of mammary glands and seminal ducts of the prostate. In each case, epithelial development is controlled by a variety of mesenchyme-derived molecules, both soluble (e.g. growth factors) and insoluble (e.g. extracellular matrix). Little is known about how these varied influences are integrated to produce a coherent morphogenetic response, but integration is likely to be achieved at least partly by cytoplasmic signal transduction networks. Work in other systems (Drosophila tracheae, MDCK models) suggests that the mitogen-activated protein (MAP) kinase pathway might be important to epithelial branching. We have investigated the role of the MAP kinase pathway in one of the best characterised mammalian examples of branching morphogenesis, the ureteric bud of the metanephric kidney. We find that Erk MAP kinase is normally active in ureteric bud, and that inhibiting Erk activation with the MAP kinase kinase inhibitor, PD98059, reversibly inhibits branching in a dose-dependent manner, while allowing tubule elongation to continue. When Erk activation is inhibited, ureteric bud tips show less cell proliferation than controls and they also produce fewer laminin-rich processes penetrating the mesenchyme and fail to show the strong concentration of apical actin filaments typical of controls; apoptosis and expression of Ret and Ros, are, however, normal. The activity of the Erk MAP kinase pathway is dependent on at least two known regulators of ureteric bud branching; the GDNF-Ret signalling system and sulphated glycosaminoglycans. MAP kinase is therefore essential for normal branching morphogenesis of the ureteric bud, and lies downstream of significant extracellular regulators of ureteric bud development.

scholarly journals Specificity of Phosphorylation Responses to Mitogen Activated Protein (MAP) Kinase Pathway Inhibitors in Melanoma Cells

2017 ◽  
Vol 17 (4) ◽  
pp. 550-564 ◽  
Author(s):  
Joel Basken ◽  
Scott A. Stuart ◽  
Andrew J. Kavran ◽  
Thomas Lee ◽  
Christopher C. Ebmeier ◽  
...  
Keyword(s):  
Map Kinase ◽  
Melanoma Cells ◽  
Protein Map ◽  
Mitogen Activated Protein ◽  
Map Kinase Pathway ◽  
Kinase Pathway

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 Regulation of Hepatitis B Virus Replication by the Ras-Mitogen-Activated Protein Kinase Signaling Pathway

2003 ◽  
Vol 77 (14) ◽  
pp. 7707-7712 ◽  
Author(s):  
Yanyan Zheng ◽  
Jie Li ◽  
Deborah L. Johnson ◽  
Jing-hsiung Ou
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Map Kinase ◽  
Deletion Mapping ◽  
Hbv Replication ◽  
B Virus ◽  
Mitogen Activated Protein ◽  
Map Kinase Pathway ◽  
External Stimuli ◽  
Kinase Pathway

ABSTRACT The replication of hepatitis B virus (HBV) can be regulated by a variety of factors, including hormones, growth factors, and cytokines. However, the molecular mechanisms of these regulations are largely unknown. Ras is a small GTPase that responds to many of these external stimuli. In this study, we investigated the possible effect of Ras on the replication of HBV. Our results indicated that activated Ras could suppress the replication of HBV in both Huh7 and HepG2 cells. This suppression was independent of the X protein and most likely occurred at the transcriptional level. Deletion-mapping analysis of the HBV core promoter and its upstream ENI and ENII enhancers revealed multiple elements responsive to activated Ras. This suppression of HBV replication by activated Ras was apparently mediated by the mitogen-activated protein (MAP) kinase pathway, as it was accompanied by activation of ERK1/2 and abolished by the MEK1/2 inhibitor U0126. Our results thus indicate that external stimuli may suppress HBV replication through the Ras-MAP kinase pathway.

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