scholarly journals Hypoxia and EGF Stimulation Regulate VEGF Expression in Human Glioblastoma Multiforme (GBM) Cells by Differential Regulation of the PI3K/Rho-GTPase and MAPK Pathways

Cells ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1397 ◽  
Author(s):  
Samer Nicolas ◽  
Sandra Abdellatef ◽  
Maria Al Haddad ◽  
Isabelle Fakhoury ◽  
Mirvat El-Sibai
Keyword(s):  
Glioblastoma Multiforme ◽  
Protein Kinase ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Small Interfering Rnas ◽  
Vegf Expression ◽  
Mapk Pathways ◽  
Egf Signaling

Glioblastoma multiforme (GBM) is one of the most common and deadly cancers of the central nervous system (CNS). It is characterized by the presence of hypoxic regions, especially in the core, leading to an increase in vascularity. This increased vascularization is driven by the expression of the major angiogenic inducer VEGF and the indirect angiogenic inducer Epidermal growth factor (EGF), which stimulates VEGF expression. In this study, we examine the regulation of VEGF by both hypoxia and the EGF signaling pathway. We also examine the involvement of pathways downstream from EGF signaling, including the mitogen-activated protein kinase/extracellular regulated kinase (MAPK/ERK) pathway and the Phosphatidylinositol-3-kinase/RhoA/C (PI3K/RhoA/C) pathway in this regulation. Our results show that VEGF expression and secretion levels increase following either hypoxia or EGF stimulation, with the two stimuli signaling in parallel. We also observed an increase in ERK and protein kinase B (Akt) phosphorylation, in response to EGF stimulation, with kinetics that correlated with the kinetics of the effect on VEGF. Using pharmacological inhibitors against ERK and PI3K and small interfering RNAs (siRNAs) against RhoA and RhoC, we found that both the ERK and the PI3K/RhoA/C pathways have to cooperate in order to lead to an increase in VEGF expression, downstream from EGF. In response to hypoxia, however, only ERK was involved in the regulation of VEGF. Hypoxia also led to a surprising decrease in the activation of PI3K and RhoA/C. Finally, the decrease in the activation of these Rho-GTPases was found to be mediated through a hypoxia-driven overexpression of the Rho-GTPase GTPase activating protein (GAP), StarD13. Therefore, while under normoxic conditions, EGF stimulates the activation of both the PI3K and the MAPK pathways and the induction of VEGF, in glioblastoma cells, hypoxic conditions lead to the suppression of the PI3K/RhoA/C pathway and an exclusive switch to the MAPK pathway.

scholarly journals Functions for Cdc42p BEM Adaptors in Regulating a Differentiation-Type MAP Kinase Pathway

2019 ◽  
Author(s):  
Sukanya Basu ◽  
Beatriz González ◽  
Boyang Li ◽  
Garrett Kimble ◽  
Keith G. Kozminski ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cell Polarity ◽  
Rho Gtpase ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
List Type ◽  
Activation Kinetics ◽  
Closed Conformation ◽  
Mapk Pathways ◽  
Effector Pathways

ABSTRACTRho GTPases regulate cell polarity and signal transduction pathways to control morphogenetic responses in different settings. In yeast, the Rho GTPase Cdc42p regulates cell polarity, and through the p21-activated kinase Ste20p, Cdc42p also regulates mitogen-activated protein kinase (MAPK) pathways (mating, filamentous growth or fMAPK, and HOG). Although much is known about how Cdc42p regulates cell polarity and the mating pathway, how Cdc42p regulates the fMAPK pathway is not clear. To address this question, Cdc42p-dependent MAPK pathways were compared in the filamentous (∑1278b) strain background. Each MAPK pathway showed a unique activation profile, with the fMAPK pathway exhibiting slow activation kinetics compared to the mating and HOG pathways. A previously characterized version of Cdc42p, Cdc42pE100A, that is specifically defective for fMAPK pathway signaling, was defective for interaction with Bem4p, the pathway-specific adaptor for the fMAPK pathway. Corresponding residues in Bem4p were identified that were required for interaction with Cdc42p and fMAPK pathway signaling. The polarity adaptor Bem1p also regulated the fMAPK pathway. In the fMAPK pathway, Bem1p recruited Ste20p to the plasma membrane, cycled between an open and closed conformation, and interacted with the GEF for Cdc42, Cdc24p. Bem1p also regulated effector pathways in different ways, behaving as a multi-functional adaptor in some pathways and an inert scaffold in others. Genetic suppression tests showed that Bem4p and Bem1p regulate the fMAPK pathway in an ordered sequence. Collectively, the study demonstrates unique and sequential functions for Rho GTPase adaptors in regulating MAPK pathways.HIGHLIGHTSComparing Cdc42p-dependent MAPK pathways showed that the fMAPK pathway had slow activation kinetics compared to the mating and HOG pathways.A collection of cdc42 alleles was tested for MAPK pathway functions. § Cdc42pE100A, previously characterized as being specifically defective for fMAPK signaling, showed reduced interaction with the fMAPK pathway adaptor Bem4p.§ Corresponding residues in Bem4p were identified that were required for interaction with Cdc42p and fMAPK signaling.The polarity adaptor Bem1p regulated the fMAPK pathway. § Bem1p regulated the fMAPK pathway by recruiting Ste20p to the plasma membrane, cycling between an open and closed conformation, and interacting with the Cdc42p GEF, Cdc24p.Different domains of Bem1p had different roles in regulating effector pathways. § Bem1p may function as a multi-functional adaptor in some pathways and an inert scaffold in others.Bem4p and Bem1p regulated the fMAPK pathway in an ordered sequence. § The data support a model where Bem4p recruits Cdc24p to GDP-Cdc42p, and Bem1p directs GTP-Cdc42p to Ste20p at the plasma membrane.§ The bud-site GTPase Rsr1p regulates Cdc24p in the fMAPK pathway but does not initiate signaling.

scholarly journals Role of Regulatory Elements and the MAPK/ERK or p38 MAPK Pathways for Activation of Human Cytomegalovirus Gene Expression

2002 ◽  
Vol 76 (10) ◽  
pp. 4873-4885 ◽  
Author(s):  
Jiping Chen ◽  
Mark F. Stinski
Keyword(s):  
Gene Expression ◽  
Protein Kinase ◽  
P38 Mapk ◽  
Human Cytomegalovirus ◽  
Mapk Pathway ◽  
Regulatory Elements ◽  
Mitogen Activated Protein Kinase ◽  
Viral Gene ◽  
Mapk Pathways ◽  
Mitogen Activated Protein

ABSTRACT A series of recombinant viruses with either site-specific mutations or various deletions of the early UL4 promoter of human cytomegalovirus were used to determine the roles of regulatory elements and the effects of the mitogen-activated protein kinase (MAPK) pathways. Viral gene expression was regulated by upstream cis-acting sites and by basic promoter elements that respond to the MAPK signal transduction pathways. Inhibitors of either the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway or the p38 MAPK pathway affected expression equally with either wild-type or mutant early UL4 promoters in the viral genome, indicating that the effects of the inhibitors are not exclusive for a single transcription factor. The minimal responsive element is the TATA box-containing early viral promoter.

scholarly journals Suppressors of a Saccharomyces cerevisiae pkc1 mutation identify alleles of the phosphatase gene PTC1 and of a novel gene encoding a putative basic leucine zipper protein.

Genetics ◽  
1995 ◽  
Vol 141 (4) ◽  
pp. 1275-1285 ◽  
Author(s):  
K N Huang ◽  
L S Symington
Keyword(s):  
Protein Kinase ◽  
Leucine Zipper ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Gene Encoding ◽  
Basic Leucine Zipper ◽  
Mapk Cascades ◽  
Synthetically Lethal

Abstract The PKC1 gene product, protein kinase C, regulates a mitogen-activated protein kinase (MAPK) cascade, which is implicated in cell wall metabolism. Previously, we identified the pkc1-4 allele in a screen for mutants with increased rates of recombination, indicating that PKC1 may also regulate DNA metabolism. The pkc1-4 allele also conferred a temperature-sensitive (ts) growth defect. Extragenic suppressors were isolated that suppress both the ts and hyperrecombination phenotypes conferred by the pkc1-4 mutation. Eight of these suppressors for into two complementation groups, designated KCS1 and KCS2. KCS1 was cloned and found to encode a novel protein with homology to the basic leucine zipper family of transcription factors. KCS2 is allelic with PTC1, a previously identified type 2C serine/threonine protein phosphatase. Although mutation of either KCS1 or PTC1 causes little apparent phenotype, the kcs1 delta ptc1 delta double mutant fails to grow at 30 degrees. Furthermore, the ptc1 deletion mutation is synthetically lethal in combination with a mutation in MPK1, which encodes a MAPK homologue proposed to act in the PKC1 pathway. Because PTC1 was initially isolated as a component of the Hog1p MAPK pathway, it appears that these two MAPK cascades share a common regulatory feature.

scholarly journals Expression of transgenes enriched in rare codons is enhanced by the MAPK pathway

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jackson Peterson ◽  
Siqi Li ◽  
Erin Kaltenbrun ◽  
Ozgun Erdogan ◽  
Christopher M. Counter
Keyword(s):  
Amino Acids ◽  
Protein Kinase ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Rare Codons ◽  
Synonymous Codons ◽  
Multiple Components ◽  
Human Genes ◽  
Regulatory Module ◽  
Mitogen Activated Protein

AbstractThe ability to translate three nucleotide sequences, or codons, into amino acids to form proteins is conserved across all organisms. All but two amino acids have multiple codons, and the frequency that such synonymous codons occur in genomes ranges from rare to common. Transcripts enriched in rare codons are typically associated with poor translation, but in certain settings can be robustly expressed, suggestive of codon-dependent regulation. Given this, we screened a gain-of-function library for human genes that increase the expression of a GFPrare reporter encoded by rare codons. This screen identified multiple components of the mitogen activated protein kinase (MAPK) pathway enhancing GFPrare expression. This effect was reversed with inhibitors of this pathway and confirmed to be both codon-dependent and occur with ectopic transcripts naturally coded with rare codons. Finally, this effect was associated, at least in part, with enhanced translation. We thus identify a potential regulatory module that takes advantage of the redundancy in the genetic code to modulate protein expression.

scholarly journals Topical Spilanthol Inhibits MAPK Signaling and Ameliorates Allergic Inflammation in DNCB-Induced Atopic Dermatitis in Mice

2019 ◽  
Vol 20 (10) ◽  
pp. 2490 ◽  
Author(s):  
Wen-Chung Huang ◽  
Chun-Hsun Huang ◽  
Sindy Hu ◽  
Hui-Ling Peng ◽  
Shu-Ju Wu
Keyword(s):  
Atopic Dermatitis ◽  
Mast Cells ◽  
Protein Kinase ◽  
Allergic Inflammation ◽  
Skin Lesions ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Mapk Pathways ◽  
Mitogen Activated Protein ◽  
Cox 2

Atopic dermatitis (AD) is a recurrent allergic skin disease caused by genetic and environmental factors. Patients with AD may experience immune imbalance, increased levels of mast cells, immunoglobulin (Ig) E and pro-inflammatory factors (Cyclooxygenase, COX-2 and inducible NO synthase, iNOS). While spilanthol (SP) has anti-inflammatory and analgesic activities, its effect on AD remains to be explored. To develop a new means of SP, inflammation-related symptoms of AD were alleviated, and 2,4-dinitrochlorobenzene (DNCB) was used to induce AD-like skin lesions in BALB/c mice. Histopathological analysis was used to examine mast cells and eosinophils infiltration in AD-like skin lesions. The levels of IgE, IgG1 and IgG2a were measured by enzyme-linked immunosorbent assay (ELISA) kits. Western blot was used for analysis of the mitogen-activated protein kinase (MAPK) pathways and COX-2 and iNOS protein expression. Topical SP treatment reduced serum IgE and IgG2a levels and suppressed COX-2 and iNOS expression via blocked mitogen-activated protein kinase (MAPK) pathways in DNCB-induced AD-like lesions. Histopathological examination revealed that SP reduced epidermal thickness and collagen accumulation and inhibited mast cells and eosinophils infiltration into the AD-like lesions skin. These results indicate that SP may protect against AD skin lesions through inhibited MAPK signaling pathways and may diminish the infiltration of inflammatory cells to block allergic inflammation.

scholarly journals Ghrelin exerts a proliferative effect on a rat pituitary somatotroph cell line via the mitogen-activated protein kinase pathway

2004 ◽  
pp. 233-240 ◽  
Author(s):  
AM Nanzer ◽  
S Khalaf ◽  
AM Mozid ◽  
RC Fowkes ◽  
MV Patel ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Protein Kinase ◽  
Cell Line ◽  
Kinase Inhibitor ◽  
Thymidine Incorporation ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Gh3 Cells ◽  
Rat Pituitary ◽  
Mitogen Activated Protein

OBJECTIVES: Ghrelin is a brain-gut peptide with GH-releasing and appetite-inducing activities and a widespread tissue distribution. Ghrelin is the endogenous ligand of the GH secretagogue receptor type 1a (GHS-R1a), and both ghrelin and the GHS-R1a are expressed in the pituitary. There are conflicting data regarding the effects of ghrelin on cell proliferation. A positive effect on proliferation and activation of the mitogen-activated protein kinase (MAPK) pathway has been found in hepatoma, adipose, cardiomyocyte and prostate cell lines. However, ghrelin has also been shown to have anti-proliferative effects on breast, lung and thyroid cell lines. We therefore examined the effect of ghrelin on the rat pituitary cell line GH3. METHODS: RT-PCR was used for the detection of GHS-R1a and pre-proghrelin mRNA expression in GH3 cells. The effect of ghrelin on cell proliferation was studied using [(3)H]thymidine incorporation; cell counting and the activation of the MAPK pathway were studied using immunoblotting and inhibitors of the extracellular signal-regulated kinase 1 and 2 (ERK 1/2), protein kinase C (PKC) and tyrosine phosphatase pathways. RESULTS: GHS-R1a and ghrelin mRNA expression were detected in GH3 cells. Ghrelin, at 10(-10) to 10(-6) M concentrations, significantly increased [(3)H]thymidine incorporation (at 10(-9) M, 183+/-13% (means+/-s.e.m.) compared with untreated controls), while 12-phorbol 13-myristate acetate (PMA) at 10(-7) M (used as a positive control) caused a 212+/-14% increase. A reproducible stimulatory effect of desoctanoyl ghrelin was also observed on [(3)H]thymidine incorporation (135+/-5%; P<0.01 at 10(-9) M compared with control), as well as on the cell count (control 6.8 x 10(4)+/-8.7 x 10(3) cells/ml vs desoctanoyl ghrelin (10(-9) M) 1.04 x 10(5)+/-7.5 x 10(3) cells/ml; P<0.01). Ghrelin caused a significant increase in phosphorylated ERK 1/2 in immunoblotting, while desoctanoyl ghrelin showed a smaller but also significant stimulatory effect. The positive effect of ghrelin and desoctanoyl ghrelin on [(3)H]thymidine incorporation was abolished by the MAPK kinase inhibitor U0126, the PKC inhibitor GF109203X and the tyrosine kinase inhibitor tyrphostin 23, suggesting that the ghrelin-induced cell proliferation of GH3 cells is mediated both via a PKC-MAPK-dependent pathway and via a tyrosine kinase-dependent pathway. This could also be clearly demonstrated by Western blot analysis, where a transient increase in ERK 1/2 phosphorylation by ghrelin was attenuated by all three inhibitors. CONCLUSION: We have shown a novel role for ghrelin in stimulating the proliferation of a somatotroph pituitary tumour cell line, suggesting that ERK activation is involved in mediating the effects of ghrelin on cell proliferation. Desoctanoyl ghrelin showed a similar effect. As ghrelin has been shown to be expressed in both normal and adenomatous pituitary tissue, locally produced ghrelin may play a role in pituitary tumorigenesis via an autocrine/paracrine pathway.

scholarly journals The vaccinia virus-stimulated mitogen-activated protein kinase (MAPK) pathway is required for virus multiplication

2004 ◽  
Vol 381 (2) ◽  
pp. 437-446 ◽  
Author(s):  
Anderson A. ANDRADE ◽  
Patrícia N. G. SILVA ◽  
Anna C. T. C. PEREIRA ◽  
Lirlândia P. de SOUSA ◽  
Paulo C. P. FERREIRA ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Vaccinia Virus ◽  
Mapk Pathway ◽  
Decisive Role ◽  
Virus Multiplication ◽  
Mitogen Activated Protein Kinase ◽  
Actin Dynamics ◽  
Kinase Activation ◽  
Mitogen Activated Protein

Early events play a decisive role in virus multiplication. We have shown previously that activation of MAPK/ERK1/2 (mitogen-activated protein kinase/extracellular-signal-regulated kinase 1/2) and protein kinase A are pivotal for vaccinia virus (VV) multiplication [de Magalhães, Andrade, Silva, Sousa, Ropert, Ferreira, Kroon, Gazzinelli and Bonjardim (2001) J. Biol. Chem. 276, 38353–38360]. In the present study, we show that VV infection provoked a sustained activation of both ERK1/2 and RSK2 (ribosomal S6 kinase 2). Our results also provide evidence that this pattern of kinase activation depends on virus multiplication and ongoing protein synthesis and is maintained independently of virus DNA synthesis. It is noteworthy that the VGF (VV growth factor), although involved, is not essential for prolonged ERK1/2 activation. Furthermore, our findings suggest that the VV-stimulated ERK1/2 activation also seems to require actin dynamics, microtubule polymerization and tyrosine kinase phosphorylation. The VV-stimulated pathway MEK/ERK1/2/RSK2 (where MEK stands for MAPK/ERK kinase) leads to phosphorylation of the ternary complex factor Elk-1 and expression of the early growth response (egr-1) gene, which kinetically paralleled the kinase activation. The recruitment of this pathway is biologically relevant, since its disruption caused a profound effect on viral thymidine kinase gene expression, viral DNA replication and VV multiplication. This pattern of sustained kinase activation after VV infection is unique. In addition, by connecting upstream signals generated at the cytoskeleton and by tyrosine kinase, the MEK/ERK1/2/RSK2 cascade seems to play a decisive role not only at early stages of the infection, i.e. post-penetration, but is also crucial to define the fate of virus progeny.

scholarly journals APPL1 mediates adiponectin-stimulated p38 MAPK activation by scaffolding the TAK1-MKK3-p38 MAPK pathway

2011 ◽  
Vol 300 (1) ◽  
pp. E103-E110 ◽  
Author(s):  
Xiaoban Xin ◽  
Lijun Zhou ◽  
Caleb M. Reyes ◽  
Feng Liu ◽  
Lily Q. Dong
Keyword(s):  
Protein Kinase ◽  
P38 Mapk ◽  
Mapk Pathway ◽  
Adaptor Protein ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Scaffolding Protein ◽  
Mapk Activation ◽  
P38 Mapk Pathway ◽  
Mitogen Activated Protein

The adaptor protein APPL1 mediates the stimulatory effect of adiponectin on p38 mitogen-activated protein kinase (MAPK) signaling, yet the underlying mechanism remains unclear. Here we show that, in C2C12 cells, overexpression or suppression of APPL1 enhanced or suppressed, respectively, adiponectin-stimulated p38 MAPK upstream kinase cascade, consisting of transforming growth factor-β-activated kinase 1 (TAK1) and mitogen-activated protein kinase kinase 3 (MKK3). In vitro affinity binding and coimmunoprecipitation experiments revealed that TAK1 and MKK3 bind to different regions of APPL1, suggesting that APPL1 functions as a scaffolding protein to facilitate adiponectin-stimulated p38 MAPK activation. Interestingly, suppressing APPL1 had no effect on TNFα-stimulated p38 MAPK phosphorylation in C2C12 myotubes, indicating that the stimulatory effect of APPL1 on p38 MAPK activation is selective. Taken together, our study demonstrated that the TAK1-MKK3 cascade mediates adiponectin signaling and uncovers a scaffolding role of APPL1 in regulating the TAK1-MKK3-p38 MAPK pathway, specifically in response to adiponectin stimulation.

scholarly journals Inactivation of Rho GTPases by Statins Attenuates Anthrax Lethal Toxin Activity

2008 ◽  
Vol 77 (1) ◽  
pp. 348-359 ◽  
Author(s):  
Aimee M. deCathelineau ◽  
Gary M. Bokoch
Keyword(s):  
Rho Gtpases ◽  
Rho Gtpase ◽  
Protective Antigen ◽  
Biological Effects ◽  
Lethal Factor ◽  
Lethal Toxin ◽  
Mitogen Activated Protein Kinase ◽  
Gtpase Activity ◽  
Anthrax Lethal Toxin ◽  
Reductase Inhibitors

ABSTRACT Anthrax lethal factor (LF), secreted by Bacillus anthracis, interacts with protective antigen to form a bipartite toxin (lethal toxin [LT]) that exerts pleiotropic biological effects resulting in subversion of the innate immune response. Although the mitogen-activated protein kinase kinases (MKKs) are the major intracellular protein targets of LF, the pathology induced by LT is not well understood. The statin family of HMG-coenzyme A reductase inhibitors have potent anti-inflammatory effects independent of their cholesterol-lowering properties, which have been attributed to modulation of Rho family GTPase activity. The Rho GTPases regulate vesicular trafficking, cytoskeletal dynamics, and cell survival and proliferation. We hypothesized that disruption of Rho GTPase function by statins might alter LT action. We show here that statins delay LT-induced death and MKK cleavage in RAW macrophages and that statin-mediated effects on LT action are attributable to disruption of Rho GTPases. The Rho GTPase-inactivating toxin, toxin B, did not significantly affect LT binding or internalization, suggesting that the Rho GTPases regulate trafficking and/or localization of LT once internalized. The use of drugs capable of inhibiting Rho GTPase activity, such as statins, may provide a means to attenuate intoxication during B. anthracis infection.

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