scholarly journals EGF stimulates gastrin promoter through activation of Sp1 kinase activity

2000 ◽  
Vol 278 (4) ◽  
pp. C697-C708 ◽  
Author(s):  
Sergey Chupreta ◽  
Ming Du ◽  
Andrea Todisco ◽  
Juanita L. Merchant
Keyword(s):  
Kinase Activity ◽  
Egf Receptor ◽  
Solid Phase ◽  
Receptor Activation ◽  
Mitogen Activated Protein Kinase ◽  
Kinase Assay ◽  
Ags Cells ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

Epidermal growth factor (EGF) receptor activation stimulates gastrin gene expression through a GC-rich element called gastrin EGF response element (gERE). This element is bound by Sp1 family members and is a target of the ras-extracellular signal-regulated kinase (Erk) signal transduction cascade. This raised the possibility that Sp1 may be phosphorylated by kinases of this signaling pathway. Erk is capable of phosphorylating other mitogen-inducible transcription factors, e.g., Elk and Sap, suggesting that Erk may also mediate EGF-dependent phosphorylation of Sp1. This possibility was tested by studying Sp1-dependent kinase activity in extracts prepared from EGF-activated AGS cells by use of solid-phase kinase assays and immunoprecipitation of metabolically labeled Sp1. The results revealed that Sp1 kinase activity (like gastrin promoter activation) is inhibited by PD-98059 and, therefore, is dependent on mitogen-activated protein kinase kinase 1 (Mek 1). However, EGF-dependent activation of endogenous Erk did not account for most of the Sp1 kinase activity, since Erk and additional Sp1 kinase activity analyzed in a solid-phase kinase assay eluted from an ion-exchange column in different fractions. Phosphoamino acid analysis of in vivo radiolabeled Sp1 demonstrated that the kinase phosphorylates Sp1 on Ser and Thr in response to EGF. Therefore, most EGF-stimulated Sp1 kinase activity is Mek 1 dependent and distinct from Erk.

Phosphorylation pattern of the p90rsk and mitogen-activated protein kinase (MAPK) molecule: comparison of in vitro and in vivo matured porcine oocytes

Zygote ◽  
2007 ◽  
Vol 15 (3) ◽  
pp. 215-223
Author(s):  
C. Schuon ◽  
S. Ebeling ◽  
B. Meinecke
Keyword(s):  
Protein Kinase ◽  
Kinase Activity ◽  
Cumulus Cells ◽  
Mek Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
Kinase Assay ◽  
Mitogen Activated Protein ◽  
Phosphorylation Pattern

SummaryThe overall objective was to elucidate the phosphorylation pattern and activity of the kinase p90rsk, a substrate of mitogen-activated protein kinase (MAPK), during in vitro and in vivo maturation of pig oocytes. Cumulus–oocyte complexes were collected from slaughtered pigs and matured in vitro (0, 22, 26, 30, 34, 46 h) with and without the MEK inhibitor U0126. For in vivo maturation, gilts were stimulated with equine chorionic gonadotrophin (eCG) (600–800 IU). Maturation was induced 72 h later with hCG (500 IU). Oocytes were obtained surgically (0, 22, 30 h). The samples were submitted to electrophoresis and protein blotting analysis. Enhanced chemiluminescence was used for visualization. In vitro matured oocytes were further submitted to a commercially available radioactive kinase assay to determine kinase activity. It was shown that oocytes, as well as cumulus cells, already possess a partially phosphorylated p90rsk at the time of removal from follicles, with a further phosphorylation of the molecule occurring between 22–24 h after the initiation of culture, and in vivo maturation. The phosphorylation of p90rsk coincides with the phosphorylation of MAPK and can be prevented by U0126, indicating a MAPK-dependent phosphorylation of p90rsk. Phosphorylation of the in vivo matured oocytes occurred shown as a band of less than 200 kDa. This is presumably a molecule complex, with MAPK not being a component. Therefore, the p90rsk molecule in vivo exists as a dimer. Determination of kinase activity demonstrated decreasing enzyme activities. This led to the conclusion that the assay is not specific for p90rsk, instead measuring p70S6 kinase activities.

scholarly journals Bromamine T (BAT) Exerts Stronger Anti-Cancer Properties than Taurine (Tau)

Cancers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 182
Author(s):  
Stella Baliou ◽  
Maria Goulielmaki ◽  
Petros Ioannou ◽  
Christina Cheimonidi ◽  
Ioannis P. Trougakos ◽  
...  
Keyword(s):  
Cytotoxic Effect ◽  
Human Colon ◽  
Mitogen Activated Protein Kinase ◽  
Mitochondrial Apoptosis ◽  
Therapeutic Modalities ◽  
Cancer Pathogenesis ◽  
Extracellular Signal ◽  
Anti Cancer ◽  
Mitogen Activated Protein

Background: Taurine (Tau) ameliorates cancer pathogenesis. Researchers have focused on the functional properties of bromamine T (BAT), a stable active bromine molecule. Both N-bromotaurine (TauNHBr) and BAT exert potent anti-inflammatory properties, but the landscape remains obscure concerning the anti-cancer effect of BAT. Methods: We used Crystal Violet, colony formation, flow cytometry and Western blot experiments to evaluate the effect of BAT and Tau on the apoptosis and autophagy of cancer cells. Xenograft experiments were used to determine the in vivo cytotoxicity of either agent. Results: We demonstrated that both BAT and Tau inhibited the growth of human colon, breast, cervical and skin cancer cell lines. Among them, BAT exerted the greatest cytotoxic effect on both RKO and MDA-MB-468 cells. In particular, BAT increased the phosphorylation of c-Jun N-terminal kinases (JNK½), p38 mitogen-activated protein kinase (MAPK), and extracellular-signal-regulated kinases (ERK½), thereby inducing mitochondrial apoptosis and autophagy in RKO cells. In contrast, Tau exerted its cytotoxic effect by upregulating JNK½ forms, thus triggering mitochondrial apoptosis in RKO cells. Accordingly, colon cancer growth was impaired in vivo. Conclusions: BAT and Tau exerted their anti-tumor properties through the induction of (i) mitochondrial apoptosis, (ii) the MAPK family, and iii) autophagy, providing novel anti-cancer therapeutic modalities.

scholarly journals A Rare p.T599dup BRAF Mutant NSCLC in a Non-Smoker

2020 ◽  
Vol 28 (1) ◽  
pp. 196-202
Author(s):  
Alla Turshudzhyan ◽  
James Vredenburgh
Keyword(s):  
Lung Cancer ◽  
Targeted Therapies ◽  
Kinase Activity ◽  
Mitogen Activated Protein Kinase ◽  
Braf Mutations ◽  
Activating Mutations ◽  
Extracellular Signal ◽  
Activating Mutation ◽  
Mitogen Activated Protein ◽  
Murine Sarcoma

V-RAF murine sarcoma viral oncogene homolog B1 (BRAF) mutated non-small-cell lung cancer (NSCLC) is an exceptionally rare form of lung cancer, found only in one to two percent of patients with an NSCLC diagnosis. BRAF NSCLC traditionally affects former or active smokers. BRAF mutations have always been of special interest to the oncological community, as they offer potential for targeted therapies. BRAF mutation spectrum includes mutations that are of both V600 and non-V600 types. BRAF V600 is an activating mutation, which results in high kinase activity and overproduction of active oncoproteins such as rapidly accelerated fibrosarcoma (RAF). This makes them susceptible to targeted therapies with RAF inhibitors. There has been little evidence, however, regarding efficacy of RAF inhibitors towards non-activating mutations that have intermediate to low kinase activity, such as non-V600 BRAF mutations. While several approaches have been investigated to overcome the limitations of RAF inhibitors, such as use of mitogen-activated protein kinase kinase (MEK) and extracellular signal-regulated kinase (ERK) inhibitors or combination of MEK and RAF inhibitors, none of them have been proven to have a superior efficacy for low kinase activity non-V600 BRAF tumors. We present a case of an extremely rare variant of NSCLC BRAF p.T599dup mutation in a non-smoker that responded to a targeted combination therapy with RAF and MEK inhibitors. The patient responded well to therapy that usually targets high kinase activity V600 mutations. Our hope is to bring more attention to non-V600 mutations and document their responses to existing and new therapies.

scholarly journals Role for the Ran Binding Protein, Mog1p, in Saccharomyces cerevisiae SLN1-SKN7 Signal Transduction

2004 ◽  
Vol 3 (6) ◽  
pp. 1544-1556 ◽  
Author(s):  
Jade Mei-Yeh Lu ◽  
Robert J. Deschenes ◽  
Jan S. Fassler
Keyword(s):  
Signal Transduction ◽  
Transcription Factor ◽  
Osmotic Stress ◽  
Kinase Activity ◽  
Mitogen Activated Protein Kinase ◽  
Osmotic Response ◽  
Mitogen Activated Protein ◽  
Kinase Pathway

ABSTRACT Yeast Sln1p is an osmotic stress sensor with histidine kinase activity. Modulation of Sln1 kinase activity in response to changes in the osmotic environment regulates the activity of the osmotic response mitogen-activated protein kinase pathway and the activity of the Skn7p transcription factor, both important for adaptation to changing osmotic stress conditions. Many aspects of Sln1 function, such as how kinase activity is regulated to allow a rapid response to the continually changing osmotic environment, are not understood. To gain insight into Sln1p function, we conducted a two-hybrid screen to identify interactors. Mog1p, a protein that interacts with the yeast Ran1 homolog, Gsp1p, was identified in this screen. The interaction with Mog1p was characterized in vitro, and its importance was assessed in vivo. mog1 mutants exhibit defects in SLN1-SKN7 signal transduction and mislocalization of the Skn7p transcription factor. The requirement for Mog1p in normal localization of Skn7p to the nucleus does not fully account for the mog1-related defects in SLN1-SKN7 signal transduction, raising the possibility that Mog1p may play a role in Skn7 binding and activation of osmotic response genes.

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 A Novel Mechanism for Mitogen-activated Protein Kinase Localization

2004 ◽  
Vol 15 (10) ◽  
pp. 4457-4466 ◽  
Author(s):  
Eric Bind ◽  
Yelena Kleyner ◽  
Dorota Skowronska-Krawczyk ◽  
Emily Bien ◽  
Brian David Dynlacht ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Subcellular Localization ◽  
Fluorescent Protein ◽  
Nuclear Translocation ◽  
Immunoblot Analysis ◽  
Mitogen Activated Protein Kinase ◽  
Carboxy Terminus ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

Mitogen-activated protein kinases/extracellular signal regulated kinases (MAPKs/ERKs) are typically thought to be soluble cytoplasmic enzymes that translocate to the nucleus subsequent to their phosphorylation by their activating kinases or mitogen-activated protein/extracellular signal regulated kinase kinase. We report here the first example of nuclear translocation of a MAPK that occurs via temporally regulated exit from a membranous organelle. Confocal microscopy examining the subcellular localization of ERK3 in several cell lines indicated that this enzyme was targeted to the Golgi/endoplasmic reticulum Golgi intermediate compartment. Deletion analysis of green fluorescent protein (GFP)-ERK3 uncovered a nuclear form that was carboxy-terminally truncated and established a Golgi targeting motif at the carboxy terminus. Immunoblot analysis of cells treated with the proteasome inhibitor MG132 further revealed two cleavage products, suggesting that in vivo, carboxy-terminal cleavage of the full-length protein controls its subcellular localization. In support of this hypothesis, we found that deletion of a small region rich in acidic residues within the carboxy terminus eliminated both the cleavage and nuclear translocation of GFP-ERK3. Finally, cell cycle synchronization studies revealed that the subcellular localization of ERK3 is temporally regulated. These data suggest a novel mechanism for the localization of an MAPK family member, ERK3, in which cell cycle-regulated, site-specific proteolysis generates the nuclear form of the protein.

scholarly journals Extracellular Signal-Regulated Kinase 2 Interacts with and Is Negatively Regulated by the LIM-Only Protein FHL2 in Cardiomyocytes

2004 ◽  
Vol 24 (3) ◽  
pp. 1081-1095 ◽  
Author(s):  
Nicole H. Purcell ◽  
Dina Darwis ◽  
Orlando F. Bueno ◽  
Judith M. Müller ◽  
Roland Schüle ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Mapk Pathway ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Erk Signaling ◽  
Interacting Protein ◽  
Hypertrophic Response ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

ABSTRACT The mitogen-activated protein kinase (MAPK) signaling pathway regulates diverse biologic functions including cell growth, differentiation, proliferation, and apoptosis. The extracellular signal-regulated kinases (ERKs) constitute one branch of the MAPK pathway that has been implicated in the regulation of cardiac differentiated growth, although the downstream mechanisms whereby ERK signaling affects this process are not well characterized. Here we performed a yeast two-hybrid screen with ERK2 bait and a cardiac cDNA library to identify novel proteins involved in regulating ERK signaling in cardiomyocytes. This screen identified the LIM-only factor FHL2 as an ERK interacting protein in both yeast and mammalian cells. In vivo, FHL2 and ERK2 colocalized in the cytoplasm at the level of the Z-line, and interestingly, FHL2 interacted more efficiently with the activated form of ERK2 than with the dephosphorylated form. ERK2 also interacted with FHL1 and FHL3 but not with the muscle LIM protein. Moreover, at least two LIM domains in FHL2 were required to mediate efficient interaction with ERK2. The interaction between ERK2 and FHL2 did not influence ERK1/2 activation, nor was FHL2 directly phosphorylated by ERK2. However, FHL2 inhibited the ability of activated ERK2 to reside within the nucleus, thus blocking ERK-dependent transcriptional responsiveness of ELK-1, GATA4, and the atrial natriuretic factor promoter. Finally, FHL2 partially antagonized the cardiac hypertrophic response induced by activated MEK-1, GATA4, and phenylephrine agonist stimulation. Collectively, these results suggest that FHL2 serves a repressor function in cardiomyocytes through its ability to inhibit ERK1/2 transcriptional coupling.

Activation of the insulin receptor (IR) by insulin and a synthetic peptide has different effects on gene expression in IR-transfected L6 myoblasts

2008 ◽  
Vol 412 (3) ◽  
pp. 435-445 ◽  
Author(s):  
Maja Jensen ◽  
Jane Palsgaard ◽  
Rehannah Borup ◽  
Pierre de Meyts ◽  
Lauge Schäffer
Keyword(s):  
Gene Expression ◽  
Insulin Receptor ◽  
Mapk Pathway ◽  
Receptor Activation ◽  
Mitogen Activated Protein Kinase ◽  
Single Chain ◽  
Therapeutic Implications ◽  
Insulin Mimetic ◽  
Mitogen Activated Protein

Single-chain peptides have been recently produced that display either mimetic or antagonistic properties against the insulin and IGF-1 (insulin-like growth factor 1) receptors. We have shown previously that the insulin mimetic peptide S597 leads to significant differences in receptor activation and initiation of downstream signalling cascades despite similar binding affinity and in vivo hypoglycaemic potency. It is still unclear how two ligands can initiate different signalling responses through the IR (insulin receptor). To investigate further how the activation of the IR by insulin and S597 differentially activates post-receptor signalling, we studied the gene expression profile in response to IR activation by either insulin or S597 using microarray technology. We found striking differences between the patterns induced by these two ligands. Most remarkable was that almost half of the genes differentially regulated by insulin and S597 were involved in cell proliferation and growth. Insulin either selectively regulated the expression of these genes or was a more potent regulator. Furthermore, we found that half of the differentially regulated genes interact with the genes involved with the MAPK (mitogen-activated protein kinase) pathway. These findings support our signalling results obtained previously and confirm that the main difference between S597 and insulin stimulation resides in the activation of the MAPK pathway. In conclusion, we show that insulin and S597 acting via the same receptor differentially affect gene expression in cells, resulting in a different mitogenicity of the two ligands, a finding which has critical therapeutic implications.

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