Region- or state-related differences in expression and activation of extracellular signal-regulated kinases (ERKs in naïve and pain-experiencing rats

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Cui Xiu-Yu

2007-07-01

Full Text Available Abstract Background Extracellular signal-regulated kinase (ERK, one member of the mitogen-activated protein kinase (MAPK family, has been suggested to regulate a diverse array of cellular functions, including cell growth, differentiation, survival, as well as neuronal plasticity. Recent evidence indicates a role for ERKs in nociceptive processing in both dorsal root ganglion and spinal cord. However, little literature has been reported to examine the differential distribution and activation of ERK isoforms, ERK1 and ERK2, at different levels of pain-related pathways under both normal and pain states. In the present study, quantitative blot immunolabeling technique was used to determine the spatial and temporal expression of ERK1 and ERK2, as well as their activated forms, in the spinal cord, primary somatosensory cortex (SI area of cortex, and hippocampus under normal, transient pain and persistent pain states. Results In naïve rats, we detected regional differences in total expression of ERK1 and ERK2 across different areas. In the spinal cord, ERK1 was expressed more abundantly than ERK2, while in the SI area of cortex and hippocampus, there was a larger amount of ERK2 than ERK1. Moreover, phosphorylated ERK2 (pERK2, not phosphorylated ERK1 (pERK1, was normally expressed with a high level in the SI area and hippocampus, but both pERK1 and pERK2 were barely detectable in normal spinal cord. Intraplantar saline or bee venom injection, mimicking transient or persistent pain respectively, can equally initiate an intense and long-lasting activation of ERKs in all three areas examined. However, isoform-dependent differences existed among these areas, that is, pERK2 exhibited stronger response than pERK1 in the spinal cord, whereas ERK1 was more remarkably activated than ERK2 in the S1 area and hippocampus. Conclusion Taken these results together, we conclude that: (1 under normal state, while ERK immunoreactivity is broadly distributed in the rat

Active Erk Regulates Microtubule Stability in H-ras-Transformed Cells

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Rene E. Harrison

2001-01-01

Full Text Available Increasing evidence suggests that activated erk regulates cell functions, at least in part, by mechanisms that do not require gene transcription. Here we show that the map kinase, erk, decorates microtubules (MTs and mitotic spindles in both parental and mutant active rastransfected 10T1 /2 fibroblasts and MCF10A breast epithelial cells. Approximately 20% of total cellular erk decorated MTs in both cell lines. A greater proportion of activated erk was associated with MTs in the presence of mutant active H-ras than in parental cells. Activation of erk by the ras pathway coincided with a decrease in the stability of MT, as detected by a stability marker. The MKK1 inhibitor, PD98059 and transfection of a dominant negative MKK1 blocked ras-induced instability of MTs but did not modify the association of erk with MTs or affect MT stability of the parental cells. These results indicate that the subset of active erk kinase that associates with MTs contributes to their instability in the presence of a mutant active ras. The MT-associated subset of active erk likely contributes to the enhanced invasive and proliferative abilities of cells containing mutant active H-ras.

Regulation of Autophagy by Kinases

International Nuclear Information System (INIS)

Sridharan, Savitha; Jain, Kirti; Basu, Alakananda

2011-01-01

Autophagy is a process of self-degradation that maintains cellular viability during periods of metabolic stress. Although autophagy is considered a survival mechanism when faced with cellular stress, extensive autophagy can also lead to cell death. Aberrations in autophagy are associated with several diseases, including cancer. Therapeutic exploitation of this process requires a clear understanding of its regulation. Although the core molecular components involved in the execution of autophagy are well studied there is limited information on how cellular signaling pathways, particularly kinases, regulate this complex process. Protein kinases are integral to the autophagy process. Atg1, the first autophagy-related protein identified, is a serine/threonine kinase and it is regulated by another serine/threonine kinase mTOR. Emerging studies suggest the participation of many different kinases in regulating various components/steps of this catabolic process. This review focuses on the regulation of autophagy by several kinases with particular emphasis on serine/threonine protein kinases such as mTOR, AMP-activated protein kinase, Akt, mitogen-activated protein kinase (ERK, p38 and JNK) and protein kinase C that are often deregulated in cancer and are important therapeutic targets

Regulation of Autophagy by Kinases

Energy Technology Data Exchange (ETDEWEB)

Sridharan, Savitha; Jain, Kirti; Basu, Alakananda, E-mail: alakananda.basu@unthsc.edu [Department of Molecular Biology and Immunology, Institute for Cancer Research, University of North Texas Health Science Center, Fort Worth, TX 76107 (United States)

2011-06-09

Autophagy is a process of self-degradation that maintains cellular viability during periods of metabolic stress. Although autophagy is considered a survival mechanism when faced with cellular stress, extensive autophagy can also lead to cell death. Aberrations in autophagy are associated with several diseases, including cancer. Therapeutic exploitation of this process requires a clear understanding of its regulation. Although the core molecular components involved in the execution of autophagy are well studied there is limited information on how cellular signaling pathways, particularly kinases, regulate this complex process. Protein kinases are integral to the autophagy process. Atg1, the first autophagy-related protein identified, is a serine/threonine kinase and it is regulated by another serine/threonine kinase mTOR. Emerging studies suggest the participation of many different kinases in regulating various components/steps of this catabolic process. This review focuses on the regulation of autophagy by several kinases with particular emphasis on serine/threonine protein kinases such as mTOR, AMP-activated protein kinase, Akt, mitogen-activated protein kinase (ERK, p38 and JNK) and protein kinase C that are often deregulated in cancer and are important therapeutic targets.

Regulation of Autophagy by Kinases

Science.gov (United States)

Sridharan, Savitha; Jain, Kirti; Basu, Alakananda

2011-01-01

Autophagy is a process of self-degradation that maintains cellular viability during periods of metabolic stress. Although autophagy is considered a survival mechanism when faced with cellular stress, extensive autophagy can also lead to cell death. Aberrations in autophagy are associated with several diseases, including cancer. Therapeutic exploitation of this process requires a clear understanding of its regulation. Although the core molecular components involved in the execution of autophagy are well studied there is limited information on how cellular signaling pathways, particularly kinases, regulate this complex process. Protein kinases are integral to the autophagy process. Atg1, the first autophagy-related protein identified, is a serine/threonine kinase and it is regulated by another serine/threonine kinase mTOR. Emerging studies suggest the participation of many different kinases in regulating various components/steps of this catabolic process. This review focuses on the regulation of autophagy by several kinases with particular emphasis on serine/threonine protein kinases such as mTOR, AMP-activated protein kinase, Akt, mitogen-activated protein kinase (ERK, p38 and JNK) and protein kinase C that are often deregulated in cancer and are important therapeutic targets. PMID:24212825

Regulation of Autophagy by Kinases

Directory of Open Access Journals (Sweden)

Savitha Sridharan

2011-06-01

Full Text Available Autophagy is a process of self-degradation that maintains cellular viability during periods of metabolic stress. Although autophagy is considered a survival mechanism when faced with cellular stress, extensive autophagy can also lead to cell death. Aberrations in autophagy are associated with several diseases, including cancer. Therapeutic exploitation of this process requires a clear understanding of its regulation. Although the core molecular components involved in the execution of autophagy are well studied there is limited information on how cellular signaling pathways, particularly kinases, regulate this complex process. Protein kinases are integral to the autophagy process. Atg1, the first autophagy-related protein identified, is a serine/threonine kinase and it is regulated by another serine/threonine kinase mTOR. Emerging studies suggest the participation of many different kinases in regulating various components/steps of this catabolic process. This review focuses on the regulation of autophagy by several kinases with particular emphasis on serine/threonine protein kinases such as mTOR, AMP-activated kinase, Akt, mitogen-activated protein kinase (ERK, p38 and JNK and protein kinase C that are often deregulated in cancer and are important therapeutic targets.

Immune responses of mussel hemocyte subpopulations are differentially regulated by enzymes of the PI 3-K, PKC, and ERK kinase families.

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García-García, Erick; Prado-Alvarez, Maria; Novoa, Beatriz; Figueras, Antonio; Rosales, Carlos

2008-01-01

Various hemocyte cell types have been described in invertebrates, but for most species a functional characterization of different hemocyte cell types is still lacking. In order to characterize some immunological properties of mussel (Mytilus galloprovincialis) hemocytes, cells were separated by flow cytometry and their capacity for phagocytosis, production of reactive oxygen species (ROS), and production of nitric oxide (NO), was examined. Phosphatidylinositol 3-kinase (PI 3-K), protein kinase C (PKC), and extracellular signal-regulated kinase (ERK) inhibitors were also used to biochemically characterize these cell responses. Four morphologically distinct subpopulations, designated R1-R4, were detected. R1, R2, and R3 cells presented different levels of phagocytosis towards zymosan, latex beads, and two bacteria species. Similarly, R1 to R3, but not R4, cells produced ROS, while all subpopulations produced NO, in response to zymosan. Internalization of all phagocytic targets was blocked by PI 3-K inhibition. In addition, internalization of latex particles, but not of bacteria, was partially blocked by PKC or ERK inhibition. Interestingly, phagocytosis of zymosan was impaired by PKC, or ERK inhibitors, only in R2 cells. Zymosan-induced ROS production was blocked by PI 3-K inhibition, but not by PKC, or ERK inhibition. In addition, zymosan-stimulated NO production was affected by PI 3-K inhibition in R1 and R2, but not in R3 or R4 cells. NO production in all cell types was unaffected by PKC inhibition, but ERK inhibition blocked it in R2 cells. These data reveal the existence of profound functional and biochemical differences in mussel hemocytes and indicate that M. galloprovincialis hemocytes are specialized cells fulfilling specific tasks in the context of host defense.

PHO-ERK1/2 interaction with mitochondria regulates the permeability transition pore in cardioprotective signaling.

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Hernández-Reséndiz, Sauri; Zazueta, Cecilia

2014-07-11

The molecular mechanism(s) by which extracellular signal-regulated kinase 1/2 (ERK1/2) and other kinases communicate with downstream targets have not been fully determined. Multiprotein signaling complexes undergoing spatiotemporal redistribution may enhance their interaction with effector proteins promoting cardioprotective response. Particularly, it has been proposed that some active kinases in association with caveolae may converge into mitochondria. Therefore, in this study we investigate if PHO-ERK1/2 interaction with mitochondria may provide a mechanistic link in the regulation of these organelles in cardioprotective signaling. Using a model of dilated cardiomyopathy followed by ischemia-reperfusion injury, we determined ERK1/2 signaling at the level of mitochondria and evaluated its effect on the permeability transition pore. The most important finding of the present study is that, under cardioprotective conditions, a subpopulation of activated ERK1/2 was directed to the mitochondrial membranes through vesicular trafficking, concurring with increased phosphorylation of mitochondrial proteins and inhibition of the mitochondrial permeability transition pore opening. In addition, our results suggest that vesicles enriched with caveolin-3 could form structures that may drive ERK1/2, GSK3β and Akt to mitochondria. Signaling complexes including PHO-ERK, PHO-Akt, PHO-eNOS and caveolin-3 contribute to cardioprotection by directly targeting the mitochondrial proteome and regulating the opening of the permeability transition pore in this model. Copyright © 2013 Elsevier Inc. All rights reserved.

Coordinating ERK signaling via the molecular scaffold Kinase Suppressor of Ras [version 1; referees: 2 approved

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Danielle Frodyma

2017-08-01

Full Text Available Many cancers, including those of the colon, lung, and pancreas, depend upon the signaling pathways induced by mutated and constitutively active Ras. The molecular scaffolds Kinase Suppressor of Ras 1 and 2 (KSR1 and KSR2 play potent roles in promoting Ras-mediated signaling through the Raf/MEK/ERK kinase cascade. Here we summarize the canonical role of KSR in cells, including its central role as a scaffold protein for the Raf/MEK/ERK kinase cascade, its regulation of various cellular pathways mediated through different binding partners, and the phenotypic consequences of KSR1 or KSR2 genetic inactivation. Mammalian KSR proteins have a demonstrated role in cellular and organismal energy balance with implications for cancer and obesity. Targeting KSR1 in cancer using small molecule inhibitors has potential for therapy with reduced toxicity to the patient. RNAi and small molecule screens using KSR1 as a reference standard have the potential to expose and target vulnerabilities in cancer. Interestingly, although KSR1 and KSR2 are similar in structure, KSR2 has a distinct physiological role in regulating energy balance. Although KSR proteins have been studied for two decades, additional analysis is required to elucidate both the regulation of these molecular scaffolds and their potent effect on the spatial and temporal control of ERK activation in health and disease.

Role and regulation of 90 kDa ribosomal S6 kinase (RSK) in signal transduction

DEFF Research Database (Denmark)

Frödin, M; Gammeltoft, S

1999-01-01

), which were among the first substrates of ERK to be discovered and which has proven to be a ubiquitous and versatile mediator of ERK signal transduction. RSK is composed of two functional kinase domains that are activated in a sequential manner by a series of phosphorylations. Recently, a family of RSK......-related kinases that are activated by ERK as well as p38 MAPK were discovered and named mitogen- and stress-activated protein kinases (MSK). A number of cellular functions of RSK have been proposed. (1) Regulation of gene expression via association and phosphorylation of transcriptional regulators including c...

Vascular endothelial growth factor signaling regulates the segregation of artery and vein via ERK activity during vascular development

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Kim, Se-Hee [McAllister Heart Institute, Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Schmitt, Christopher E.; Woolls, Melissa J. [McAllister Heart Institute, Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Yale Cardiovascular Research Center and Section of Cardiovascular Medicine, Dept. of Internal Medicine, Yale University School of Medicine, New Haven, CT 06511 (United States); Holland, Melinda B. [McAllister Heart Institute, Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Kim, Jun-Dae [Yale Cardiovascular Research Center and Section of Cardiovascular Medicine, Dept. of Internal Medicine, Yale University School of Medicine, New Haven, CT 06511 (United States); Jin, Suk-Won, E-mail: suk-won.jin@yale.edu [Yale Cardiovascular Research Center and Section of Cardiovascular Medicine, Dept. of Internal Medicine, Yale University School of Medicine, New Haven, CT 06511 (United States)

2013-01-25

Highlights: ► VEGF-A signaling regulates the segregation of axial vessels. ► VEGF-A signaling is mediated by PKC and ERK in this process. ► Ectopic activation of ERK is sufficient to rescue defects in vessel segregation. -- Abstract: Segregation of two axial vessels, the dorsal aorta and caudal vein, is one of the earliest patterning events occur during development of vasculature. Despite the importance of this process and recent advances in our understanding on vascular patterning during development, molecular mechanisms that coordinate the segregation of axial vessels remain largely elusive. In this report, we find that vascular endothelial growth factor-A (Vegf-A) signaling regulates the segregation of dorsal aorta and axial vein during development. Inhibition of Vegf-A pathway components including ligand Vegf-A and its cognate receptor Kdrl, caused failure in segregation of axial vessels in zebrafish embryos. Similarly, chemical inhibition of Mitogen-activated protein kinase kinase (Map2k1)/Extracellular-signal-regulated kinases (Erk) and phosphatidylinositol 3-kinases (PI3 K), which are downstream effectors of Vegf-A signaling pathway, led to the fusion of two axial vessels. Moreover, we find that restoring Erk activity by over-expression of constitutively active MEK in embryos with a reduced level of Vegf-A signaling can rescue the defects in axial vessel segregation. Taken together, our data show that segregation of axial vessels requires the function of Vegf-A signaling, and Erk may function as the major downstream effector in this process.

Vascular endothelial growth factor signaling regulates the segregation of artery and vein via ERK activity during vascular development

International Nuclear Information System (INIS)

Kim, Se-Hee; Schmitt, Christopher E.; Woolls, Melissa J.; Holland, Melinda B.; Kim, Jun-Dae; Jin, Suk-Won

2013-01-01

Highlights: ► VEGF-A signaling regulates the segregation of axial vessels. ► VEGF-A signaling is mediated by PKC and ERK in this process. ► Ectopic activation of ERK is sufficient to rescue defects in vessel segregation. -- Abstract: Segregation of two axial vessels, the dorsal aorta and caudal vein, is one of the earliest patterning events occur during development of vasculature. Despite the importance of this process and recent advances in our understanding on vascular patterning during development, molecular mechanisms that coordinate the segregation of axial vessels remain largely elusive. In this report, we find that vascular endothelial growth factor-A (Vegf-A) signaling regulates the segregation of dorsal aorta and axial vein during development. Inhibition of Vegf-A pathway components including ligand Vegf-A and its cognate receptor Kdrl, caused failure in segregation of axial vessels in zebrafish embryos. Similarly, chemical inhibition of Mitogen-activated protein kinase kinase (Map2k1)/Extracellular-signal-regulated kinases (Erk) and phosphatidylinositol 3-kinases (PI3 K), which are downstream effectors of Vegf-A signaling pathway, led to the fusion of two axial vessels. Moreover, we find that restoring Erk activity by over-expression of constitutively active MEK in embryos with a reduced level of Vegf-A signaling can rescue the defects in axial vessel segregation. Taken together, our data show that segregation of axial vessels requires the function of Vegf-A signaling, and Erk may function as the major downstream effector in this process

Oscillatory Dynamics of the Extracellular Signal-regulated Kinase Pathway

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Shankaran, Harish; Wiley, H. S.

2010-12-01

The extracellular signal-regulated kinase (ERK) pathway is a central signaling pathway in development and disease and is regulated by multiple negative and positive feedback loops. Recent studies have shown negative feedback from ERK to upstream regulators can give rise to biochemical oscillations with a periodicity of between 15-30 minutes. Feedback due to the stimulated transcription of negative regulators of the ERK pathway can also give rise to transcriptional oscillations with a periodicity of 1-2h. The biological significance of these oscillations is not clear, but recent evidence suggests that transcriptional oscillations participate in developmental processes, such as somite formation. Biochemical oscillations are more enigmatic, but could provide a mechanism for encoding different types of inputs into a common signaling pathway.

Basic Fibroblast Growth Factor Regulates Persistent ERK Osciliations in Premaligant but not Malignant JB6 Cells

Energy Technology Data Exchange (ETDEWEB)

Weber, Thomas J.; Shankaran, Harish; Wiley, H. S.; Opresko, Lee K.; Chrisler, William B.; Quesenberry, Ryan D.

2010-05-02

basic fibroblast growth factor (bFGF or FGF2) plays an important role in epidermal wound healing in vivo and is associated with a persistent increased in the extracellular signal-regulated kinase (ERK) pathway in vitro. Here we have examined whether bFGF induces the closure of an experimental scratch wound in JB6 mouse epidermal cells and have explored the regulation of the ERK pathway by bFGF in the context of kinase oscillations. bFGF stimulation is associated with increases in cellular phospho-ERK and phospho-c-Jun levels. In addition, bFGF increases cell proliferation and a change in cell morphology (stellate appearance) in a dose-dependent fashion (0.1 – 100 ng/ml). bFGF treatment also promoted the closure of an experimental scratch wound in vitro. JB6 cells were stably transfected with an ERK1-GFP chimera to follow temporal ERK subcellular distribution patterns. We observe a persistent upregulation of the ERK pathway, as evidenced by a significant increase in nuclear ERK1-GFP levels at time points up to 24 hr after bFGF treatment. Interestingly, at the single cell level, ERK is observed to oscillate between nuclear and cytosolic compartments in response to bFGF treatment. Because this oscillatory behavior is asynchronous in the cell population, it is only clearly resolved at the single cell level. Collectively, data presented here are consistent with an important role for bFGF in wound healing and suggest a more complex regulation of the ERK pathway by bFGF than has previously been appreciated.

Thioredoxin-1 promotes survival in cells exposed to S-nitrosoglutathione: Correlation with reduction of intracellular levels of nitrosothiols and up-regulation of the ERK1/2 MAP Kinases

International Nuclear Information System (INIS)

Arai, Roberto J.; Ogata, Fernando T.; Batista, Wagner L.; Masutani, Hiroshi; Yodoi, Junji; Debbas, Victor; Augusto, Ohara; Stern, Arnold; Monteiro, Hugo P.

2008-01-01

Accumulating evidence indicates that post-translational protein modifications by nitric oxide and its derived species are critical effectors of redox signaling in cells. These protein modifications are most likely controlled by intracellular reductants. Among them, the importance of the 12 kDa dithiol protein thioredoxin-1 (TRX-1) has been increasingly recognized. However, the effects of TRX-1 in cells exposed to exogenous nitrosothiols remain little understood. We investigated the levels of intracellular nitrosothiols and survival signaling in HeLa cells over-expressing TRX-1 and exposed to S-nitrosoglutahione (GSNO). A role for TRX-1 expression on GSNO catabolism and cell viability was demonstrated by the concentration-dependent effects of GSNO on decreasing TRX-1 expression, activation of caspase-3, and increasing cell death. The over-expression of TRX-1 in HeLa cells partially attenuated caspase-3 activation and enhanced cell viability upon GSNO treatment. This was correlated with reduction of intracellular levels of nitrosothiols and increasing levels of nitrite and nitrotyrosine. The involvement of ERK, p38 and JNK pathways were investigated in parental cells treated with GSNO. Activation of ERK1/2 MAP kinases was shown to be critical for survival signaling. In cells over-expressing TRX-1, basal phosphorylation levels of ERK1/2 MAP kinases were higher and further increased after GSNO treatment. These results indicate that the enhanced cell viability promoted by TRX-1 correlates with its capacity to regulate the levels of intracellular nitrosothiols and to up-regulate the survival signaling pathway mediated by the ERK1/2 MAP kinases

The amoebal MAP kinase response to Legionella pneumophila is regulated by DupA.

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Li, Zhiru; Dugan, Aisling S; Bloomfield, Gareth; Skelton, Jason; Ivens, Alasdair; Losick, Vicki; Isberg, Ralph R

2009-09-17

The amoeba Dictyostelium discoideum can support replication of Legionella pneumophila. Here we identify the dupA gene, encoding a putative tyrosine kinase/dual-specificity phosphatase, in a screen for D. discoideum mutants altered in allowing L. pneumophila intracellular replication. Inactivation of dupA resulted in depressed L. pneumophila growth and sustained hyperphosphorylation of the amoebal MAP kinase ERK1, consistent with loss of a phosphatase activity. Bacterial challenge of wild-type amoebae induced dupA expression and resulted in transiently increased ERK1 phosphorylation, suggesting that dupA and ERK1 are part of a response to bacteria. Indeed, over 500 of the genes misregulated in the dupA(-) mutant were regulated in response to L. pneumophila infection, including some thought to have immune-like functions. MAP kinase phosphatases are known to be highly upregulated in macrophages challenged with L. pneumophila. Thus, DupA may regulate a MAP kinase response to bacteria that is conserved from amoebae to mammals.

Recognition of ERK MAP kinase by PEA-15 reveals a common docking site within the death domain and death effector domain

OpenAIRE

Hill, Justine M.; Vaidyanathan, Hema; Ramos, Joe W.; Ginsberg, Mark H.; Werner, Milton H.

2002-01-01

PEA-15 is a multifunctional protein that modulates signaling pathways which control cell proliferation and cell death. In particular, PEA-15 regulates the actions of the ERK MAP kinase cascade by binding to ERK and altering its subcellular localization. The three-dimensional structure of PEA-15 has been determined using NMR spectroscopy and its interaction with ERK defined by characterization of mutants that modulate ERK function. PEA-15 is composed of an N-terminal death effector domain (DED...

Inhibiting Src family tyrosine kinase activity blocks glutamate signalling to ERK1/2 and Akt/PKB but not JNK in cultured striatal neurones.

Science.gov (United States)

Crossthwaite, Andrew J; Valli, Haseeb; Williams, Robert J

2004-03-01

Glutamate receptor activation of mitogen-activated protein (MAP) kinase signalling cascades has been implicated in diverse neuronal functions such as synaptic plasticity, development and excitotoxicity. We have previously shown that Ca2+-influx through NMDA receptors in cultured striatal neurones mediates the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt/protein kinase B (PKB) through a phosphatidylinositol 3-kinase (PI 3-kinase)-dependent pathway. Exposing neurones to the Src family tyrosine kinase inhibitor PP2, but not the inactive analogue PP3, inhibited NMDA receptor-induced phosphorylation of ERK1/2 and Akt/PKB in a concentration-dependent manner, and reduced cAMP response element-binding protein (CREB) phosphorylation. To establish a link between Src family tyrosine kinase-mediated phosphorylation and PI 3-kinase signalling, affinity precipitation experiments were performed with the SH2 domains of the PI 3-kinase regulatory subunit p85. This revealed a Src-dependent phosphorylation of a focal adhesion kinase (FAK)-p85 complex on glutamate stimulation. Demonstrating that PI3-kinase is not ubiquitously involved in NMDA receptor signal transduction, the PI 3-kinase inhibitors wortmannin and LY294002 did not prevent NMDA receptor Ca2+-dependent phosphorylation of c-Jun N-terminal kinase 1/2 (JNK1/2). Further, inhibiting Src family kinases increased NMDA receptor-dependent JNK1/2 phosphorylation, suggesting that Src family kinase-dependent cascades may physiologically limit signalling to JNK. These results demonstrate that Src family tyrosine kinases and PI3-kinase are pivotal regulators of NMDA receptor signalling to ERK/Akt and JNK in striatal neurones.

Role of nongenomic activation of phosphatidylinositol 3-kinase/Akt and mitogen-activated protein kinase/extracellular signal-regulated kinase kinase/extracellular signal-regulated kinase 1/2 pathways in 1,25D3-mediated apoptosis in squamous cell carcinoma cells.

Science.gov (United States)

Ma, Yingyu; Yu, Wei-Dong; Kong, Rui-Xian; Trump, Donald L; Johnson, Candace S

2006-08-15

Vitamin D is a steroid hormone that regulates calcium homeostasis and bone metabolism. The active form of vitamin D [1 alpha,25-dihydroxyvitamin D(3) (1,25D3)] acts through both genomic and nongenomic pathways. 1,25D3 has antitumor effects in a variety of cancers, including colorectal, prostate, breast, ovarian, and skin cancers. 1,25D3 exerts growth-inhibitory effects in cancer cells through the induction of apoptosis, cell cycle arrest, and differentiation. The mechanisms regulating 1,25D3-induced apoptosis remain unclear. We investigated the role of nongenomic signaling in 1,25D3-mediated apoptosis in squamous cell carcinoma (SCC) cells. 1,25D3 induced rapid and sustained activation of phosphatidylinositol 3-kinase/Akt and mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) 1/2 pathways in SCC cells. These effects were nongenomic: they occurred rapidly and were not inhibited by cycloheximide or actinomycin D. To examine whether the nongenomic activation of Akt and ERK1/2 plays a role in 1,25D3-mediated apoptosis, the expression of Akt or ERK1/2 was reduced by small interfering RNA (siRNA). siRNA-Akt significantly enhanced 1,25D3-induced apoptosis as indicated by increased levels of Annexin V-positive cells and increased sub-G(1) population and DNA fragmentation. In contrast, siRNA-ERK1/2 had no effects on 1,25D3-induced apoptosis. In addition, siRNA-Akt transfection followed by 1,25D3 treatment induced apoptosis much sooner than 1,25D3 alone. siRNA-Akt and 1,25D3 induced caspase-10 activation, suppressed the expression of c-IAP1 and XIAP, and promoted 1,25D3-induced caspase-3 activation. These results support a link between 1,25D3-induced nongenomic signaling and apoptosis. 1,25D3 induces the activation of phosphatidylinositol 3-kinase/Akt, which suppresses 1,25D3-mediated apoptosis and prolongs the survival of SCC cells.

Norathyriol Suppresses Skin Cancers Induced by Solar Ultraviolet Radiation by Targeting ERK Kinases

Energy Technology Data Exchange (ETDEWEB)

Li, Jixia; Malakhova, Margarita; Mottamal, Madhusoodanan; Reddy, Kanamata; Kurinov, Igor; Carper, Andria; Langfald, Alyssa; Oi, Naomi; Kim, Myoung Ok; Zhu, Feng; Sosa, Carlos P.; Zhou, Keyuan; Bode, Ann M.; Dong, Zigang (Cornell); (Guangdong); (UMM)

2012-06-27

Ultraviolet (UV) irradiation is the leading factor in the development of skin cancer, prompting great interest in chemopreventive agents for this disease. In this study, we report the discovery of norathyriol, a plant-derived chemopreventive compound identified through an in silico virtual screening of the Chinese Medicine Library. Norathyriol is a metabolite of mangiferin found in mango, Hypericum elegans, and Tripterospermum lanceolatum and is known to have anticancer activity. Mechanistic investigations determined that norathyriol acted as an inhibitor of extracellular signal-regulated kinase (ERK)1/2 activity to attenuate UVB-induced phosphorylation in mitogen-activated protein kinases signaling cascades. We confirmed the direct and specific binding of norathyriol with ERK2 through a cocrystal structural analysis. The xanthone moiety in norathyriol acted as an adenine mimetic to anchor the compound by hydrogen bonds to the hinge region of the protein ATP-binding site on ERK2. Norathyriol inhibited in vitro cell growth in mouse skin epidermal JB6 P+ cells at the level of G{sub 2}-M phase arrest. In mouse skin tumorigenesis assays, norathyriol significantly suppressed solar UV-induced skin carcinogenesis. Further analysis indicated that norathyriol mediates its chemopreventive activity by inhibiting the ERK-dependent activity of transcriptional factors AP-1 and NF-{kappa}B during UV-induced skin carcinogenesis. Taken together, our results identify norathyriol as a safe new chemopreventive agent that is highly effective against development of UV-induced skin cancer.

Polymeric immunoglobulin receptor-mediated invasion of Streptococcus pneumoniae into host cells requires a coordinate signaling of SRC family of protein-tyrosine kinases, ERK, and c-Jun N-terminal kinase.

Science.gov (United States)

Agarwal, Vaibhav; Asmat, Tauseef M; Dierdorf, Nina I; Hauck, Christof R; Hammerschmidt, Sven

2010-11-12

Streptococcus pneumoniae are commensals of the human nasopharynx with the capacity to invade mucosal respiratory cells. PspC, a pneumococcal surface protein, interacts with the human polymeric immunoglobulin receptor (pIgR) to promote bacterial adherence to and invasion into epithelial cells. Internalization of pneumococci requires the coordinated action of actin cytoskeleton rearrangements and the retrograde machinery of pIgR. Here, we demonstrate the involvement of Src protein-tyrosine kinases (PTKs), focal adhesion kinase (FAK), extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK) but not p38 mitogen-activated protein kinases (MAPK) in pneumococcal invasion via pIgR. Pharmacological inhibitors of PTKs and MAPKs and genetic interference with Src PTK and FAK functions caused a significant reduction of pIgR-mediated pneumococcal invasion but did not influence bacterial adhesion to host cells. Furthermore, pneumococcal ingestion by host cells induces activation of ERK1/2 and JNK. In agreement with activated JNK, its target molecule and DNA-binding protein c-Jun was phosphorylated. We also show that functionally active Src PTK is essential for activation of ERK1/2 upon pneumococcal infections. In conclusion, these data illustrate the importance of a coordinated signaling between Src PTKs, ERK1/2, and JNK during PspC-pIgR-mediated uptake of pneumococci by host epithelial cells.

PI3 kinase is important for Ras, MEK and Erk activation of Epo-stimulated human erythroid progenitors

Directory of Open Access Journals (Sweden)

Schmidt Enrico K

2004-05-01

Full Text Available Abstract Background Erythropoietin is a multifunctional cytokine which regulates the number of erythrocytes circulating in mammalian blood. This is crucial in order to maintain an appropriate oxygen supply throughout the body. Stimulation of primary human erythroid progenitors (PEPs with erythropoietin (Epo leads to the activation of the mitogenic kinases (MEKs and Erks. How this is accomplished mechanistically remained unclear. Results Biochemical studies with human cord blood-derived PEPs now show that Ras and the class Ib enzyme of the phosphatidylinositol-3 kinase (PI3K family, PI3K gamma, are activated in response to minimal Epo concentrations. Surprisingly, three structurally different PI3K inhibitors block Ras, MEK and Erk activation in PEPs by Epo. Furthermore, Erk activation in PEPs is insensitive to the inhibition of Raf kinases but suppressed upon PKC inhibition. In contrast, Erk activation induced by stem cell factor, which activates c-Kit in the same cells, is sensitive to Raf inhibition and insensitive to PI3K and PKC inhibitors. Conclusions These unexpected findings contrast with previous results in human primary cells using Epo at supraphysiological concentrations and open new doors to eventually understanding how low Epo concentrations mediate the moderate proliferation of erythroid progenitors under homeostatic blood oxygen levels. They indicate that the basal activation of MEKs and Erks in PEPs by minimal concentrations of Epo does not occur through the classical cascade Shc/Grb2/Sos/Ras/Raf/MEK/Erk. Instead, MEKs and Erks are signal mediators of PI3K, probably the recently described PI3K gamma, through a Raf-independent signaling pathway which requires PKC activity. It is likely that higher concentrations of Epo that are induced by hypoxia, for example, following blood loss, lead to additional mitogenic signals which greatly accelerate erythroid progenitor proliferation.

Inducible Activation of ERK5 MAP Kinase Enhances Adult Neurogenesis in the Olfactory Bulb and Improves Olfactory Function

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Wang, Wenbin; Lu, Song; Li, Tan; Pan, Yung-Wei; Zou, Junhui; Abel, Glen M.; Xu, Lihong; Storm, Daniel R.

2015-01-01

Recent discoveries have suggested that adult neurogenesis in the subventricular zone (SVZ) and olfactory bulb (OB) may be required for at least some forms of olfactory behavior in mice. However, it is unclear whether conditional and selective enhancement of adult neurogenesis by genetic approaches is sufficient to improve olfactory function under physiological conditions or after injury. Furthermore, specific signaling mechanisms regulating adult neurogenesis in the SVZ/OB are not fully defined. We previously reported that ERK5, a MAP kinase selectively expressed in the neurogenic regions of the adult brain, plays a critical role in adult neurogenesis in the SVZ/OB. Using a site-specific knock-in mouse model, we report here that inducible and targeted activation of the endogenous ERK5 in adult neural stem/progenitor cells enhances adult neurogenesis in the OB by increasing cell survival and neuronal differentiation. This conditional ERK5 activation also improves short-term olfactory memory and odor-cued associative olfactory learning under normal physiological conditions. Furthermore, these mice show enhanced recovery of olfactory function and have more adult-born neurons after a zinc sulfate-induced lesion of the main olfactory epithelium. We conclude that ERK5 MAP kinase is an important endogenous signaling pathway regulating adult neurogenesis in the SVZ/OB, and that conditional activation of endogenous ERK5 is sufficient to enhance adult neurogenesis in the OB thereby improving olfactory function both under normal conditions and after injury. PMID:25995470

Trihydrophobin 1 Phosphorylation by c-Src Regulates MAPK/ERK Signaling and Cell Migration

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Wu, Weibin; Sun, Zhichao; Wu, Jingwen; Peng, Xiaomin; Gan, Huacheng; Zhang, Chunyi; Ji, Lingling; Xie, Jianhui; Zhu, Haiyan; Ren, Shifang

2012-01-01

c-Src activates Ras-MAPK/ERK signaling pathway and regulates cell migration, while trihydrophobin 1 (TH1) inhibits MAPK/ERK activation and cell migration through interaction with A-Raf and PAK1 and inhibiting their kinase activities. Here we show that c-Src interacts with TH1 by GST-pull down assay, coimmunoprecipitation and confocal microscopy assay. The interaction leads to phosphorylation of TH1 at Tyr-6 in vivo and in vitro. Phosphorylation of TH1 decreases its association with A-Raf and PAK1. Further study reveals that Tyr-6 phosphorylation of TH1 reduces its inhibition on MAPK/ERK signaling, enhances c-Src mediated cell migration. Moreover, induced tyrosine phosphorylation of TH1 has been found by EGF and estrogen treatments. Taken together, our findings demonstrate a novel mechanism for the comprehensive regulation of Ras/Raf/MEK/ERK signaling and cell migration involving tyrosine phosphorylation of TH1 by c-Src. PMID:22238675

High-Throughput Screening and Hit Validation of Extracellular-Related Kinase 5 (ERK5) Inhibitors.

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Myers, Stephanie M; Bawn, Ruth H; Bisset, Louise C; Blackburn, Timothy J; Cottyn, Betty; Molyneux, Lauren; Wong, Ai-Ching; Cano, Celine; Clegg, William; Harrington, Ross W; Leung, Hing; Rigoreau, Laurent; Vidot, Sandrine; Golding, Bernard T; Griffin, Roger J; Hammonds, Tim; Newell, David R; Hardcastle, Ian R

2016-08-08

The extracellular-related kinase 5 (ERK5) is a promising target for cancer therapy. A high-throughput screen was developed for ERK5, based on the IMAP FP progressive binding system, and used to identify hits from a library of 57 617 compounds. Four distinct chemical series were evident within the screening hits. Resynthesis and reassay of the hits demonstrated that one series did not return active compounds, whereas three series returned active hits. Structure-activity studies demonstrated that the 4-benzoylpyrrole-2-carboxamide pharmacophore had excellent potential for further development. The minimum kinase binding pharmacophore was identified, and key examples demonstrated good selectivity for ERK5 over p38α kinase.

Protein kinase C regulates human pluripotent stem cell self-renewal.

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Masaki Kinehara

Full Text Available The self-renewal of human pluripotent stem (hPS cells including embryonic stem and induced pluripotent stem cells have been reported to be supported by various signal pathways. Among them, fibroblast growth factor-2 (FGF-2 appears indispensable to maintain self-renewal of hPS cells. However, downstream signaling of FGF-2 has not yet been clearly understood in hPS cells.In this study, we screened a kinase inhibitor library using a high-throughput alkaline phosphatase (ALP activity-based assay in a minimal growth factor-defined medium to understand FGF-2-related molecular mechanisms regulating self-renewal of hPS cells. We found that in the presence of FGF-2, an inhibitor of protein kinase C (PKC, GF109203X (GFX, increased ALP activity. GFX inhibited FGF-2-induced phosphorylation of glycogen synthase kinase-3β (GSK-3β, suggesting that FGF-2 induced PKC and then PKC inhibited the activity of GSK-3β. Addition of activin A increased phosphorylation of GSK-3β and extracellular signal-regulated kinase-1/2 (ERK-1/2 synergistically with FGF-2 whereas activin A alone did not. GFX negated differentiation of hPS cells induced by the PKC activator, phorbol 12-myristate 13-acetate whereas Gö6976, a selective inhibitor of PKCα, β, and γ isoforms could not counteract the effect of PMA. Intriguingly, functional gene analysis by RNA interference revealed that the phosphorylation of GSK-3β was reduced by siRNA of PKCδ, PKCε, and ζ, the phosphorylation of ERK-1/2 was reduced by siRNA of PKCε and ζ, and the phosphorylation of AKT was reduced by PKCε in hPS cells.Our study suggested complicated cross-talk in hPS cells that FGF-2 induced the phosphorylation of phosphatidylinositol-3 kinase (PI3K/AKT, mitogen-activated protein kinase/ERK-1/2 kinase (MEK, PKC/ERK-1/2 kinase, and PKC/GSK-3β. Addition of GFX with a MEK inhibitor, U0126, in the presence of FGF-2 and activin A provided a long-term stable undifferentiated state of hPS cells even though h

Protein Kinase C Regulates Human Pluripotent Stem Cell Self-Renewal

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Kinehara, Masaki; Kawamura, Suguru; Tateyama, Daiki; Suga, Mika; Matsumura, Hiroko; Mimura, Sumiyo; Hirayama, Noriko; Hirata, Mitsuhi; Uchio-Yamada, Kozue; Kohara, Arihiro; Yanagihara, Kana; Furue, Miho K.

2013-01-01

Background The self-renewal of human pluripotent stem (hPS) cells including embryonic stem and induced pluripotent stem cells have been reported to be supported by various signal pathways. Among them, fibroblast growth factor-2 (FGF-2) appears indispensable to maintain self-renewal of hPS cells. However, downstream signaling of FGF-2 has not yet been clearly understood in hPS cells. Methodology/Principal Findings In this study, we screened a kinase inhibitor library using a high-throughput alkaline phosphatase (ALP) activity-based assay in a minimal growth factor-defined medium to understand FGF-2-related molecular mechanisms regulating self-renewal of hPS cells. We found that in the presence of FGF-2, an inhibitor of protein kinase C (PKC), GF109203X (GFX), increased ALP activity. GFX inhibited FGF-2-induced phosphorylation of glycogen synthase kinase-3β (GSK-3β), suggesting that FGF-2 induced PKC and then PKC inhibited the activity of GSK-3β. Addition of activin A increased phosphorylation of GSK-3β and extracellular signal-regulated kinase-1/2 (ERK-1/2) synergistically with FGF-2 whereas activin A alone did not. GFX negated differentiation of hPS cells induced by the PKC activator, phorbol 12-myristate 13-acetate whereas Gö6976, a selective inhibitor of PKCα, β, and γ isoforms could not counteract the effect of PMA. Intriguingly, functional gene analysis by RNA interference revealed that the phosphorylation of GSK-3β was reduced by siRNA of PKCδ, PKCε, and ζ, the phosphorylation of ERK-1/2 was reduced by siRNA of PKCε and ζ, and the phosphorylation of AKT was reduced by PKCε in hPS cells. Conclusions/Significance Our study suggested complicated cross-talk in hPS cells that FGF-2 induced the phosphorylation of phosphatidylinositol-3 kinase (PI3K)/AKT, mitogen-activated protein kinase/ERK-1/2 kinase (MEK), PKC/ERK-1/2 kinase, and PKC/GSK-3β. Addition of GFX with a MEK inhibitor, U0126, in the presence of FGF-2 and activin A provided a long

The human Na⁺/H⁺ exchanger 1 is a membrane scaffold protein for extracellular signal-regulated kinase 2

DEFF Research Database (Denmark)

Hendus-Altenburger, Ruth; Pedraz Cuesta, Elena; Olesen, Christina Wilkens

2016-01-01

BACKGROUND: Extracellular signal-regulated kinase 2 (ERK2) is an S/T kinase with more than 200 known substrates, and with critical roles in regulation of cell growth and differentiation and currently no membrane proteins have been linked to ERK2 scaffolding. METHODS AND RESULTS: Here, we identify...

Inducible activation of ERK5 MAP kinase enhances adult neurogenesis in the olfactory bulb and improves olfactory function.

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Wang, Wenbin; Lu, Song; Li, Tan; Pan, Yung-Wei; Zou, Junhui; Abel, Glen M; Xu, Lihong; Storm, Daniel R; Xia, Zhengui

2015-05-20

Recent discoveries have suggested that adult neurogenesis in the subventricular zone (SVZ) and olfactory bulb (OB) may be required for at least some forms of olfactory behavior in mice. However, it is unclear whether conditional and selective enhancement of adult neurogenesis by genetic approaches is sufficient to improve olfactory function under physiological conditions or after injury. Furthermore, specific signaling mechanisms regulating adult neurogenesis in the SVZ/OB are not fully defined. We previously reported that ERK5, a MAP kinase selectively expressed in the neurogenic regions of the adult brain, plays a critical role in adult neurogenesis in the SVZ/OB. Using a site-specific knock-in mouse model, we report here that inducible and targeted activation of the endogenous ERK5 in adult neural stem/progenitor cells enhances adult neurogenesis in the OB by increasing cell survival and neuronal differentiation. This conditional ERK5 activation also improves short-term olfactory memory and odor-cued associative olfactory learning under normal physiological conditions. Furthermore, these mice show enhanced recovery of olfactory function and have more adult-born neurons after a zinc sulfate-induced lesion of the main olfactory epithelium. We conclude that ERK5 MAP kinase is an important endogenous signaling pathway regulating adult neurogenesis in the SVZ/OB, and that conditional activation of endogenous ERK5 is sufficient to enhance adult neurogenesis in the OB thereby improving olfactory function both under normal conditions and after injury. Copyright © 2015 the authors 0270-6474/15/357833-17$15.00/0.

Adaptation to TKI Treatment Reactivates ERK Signaling in Tyrosine Kinase-Driven Leukemias and Other Malignancies.

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Bruner, J Kyle; Ma, Hayley S; Li, Li; Qin, Alice Can Ran; Rudek, Michelle A; Jones, Richard J; Levis, Mark J; Pratz, Keith W; Pratilas, Christine A; Small, Donald

2017-10-15

FMS-like tyrosine kinase-3 (FLT3) tyrosine kinase inhibitors (TKI) have been tested extensively to limited benefit in acute myeloid leukemia (AML). We hypothesized that FLT3/internal tandem duplication (ITD) leukemia cells exhibit mechanisms of intrinsic signaling adaptation to TKI treatment that are associated with an incomplete response. Here, we identified reactivation of ERK signaling within hours following treatment of FLT3/ITD AML cells with selective inhibitors of FLT3. When these cells were treated with inhibitors of both FLT3 and MEK in combination, ERK reactivation was abrogated and anti-leukemia effects were more pronounced compared with either drug alone. ERK reactivation was also observed following inhibition of other tyrosine kinase-driven cancer cells, including EGFR-mutant lung cancer, HER2-amplified breast cancer, and BCR-ABL leukemia. These studies reveal an adaptive feedback mechanism in tyrosine kinase-driven cancers associated with reactivation of ERK signaling in response to targeted inhibition. Cancer Res; 77(20); 5554-63. ©2017 AACR . ©2017 American Association for Cancer Research.

Extracellular signal regulated kinase 5 mediates signals triggered by the novel tumor promoter palytoxin

International Nuclear Information System (INIS)

Charlson, Aaron T.; Zeliadt, Nicholette A.; Wattenberg, Elizabeth V.

2009-01-01

Palytoxin is classified as a non-12-O-tetradecanoylphorbol-13-acetate (TPA)-type skin tumor because it does not bind to or activate protein kinase C. Palytoxin is thus a novel tool for investigating alternative signaling pathways that may affect carcinogenesis. We previously showed that palytoxin activates three major members of the mitogen activated protein kinase (MAPK) family, extracellular signal regulated kinase 1 and 2 (ERK1/2), c-Jun N-terminal kinase (JNK), and p38. Here we report that palytoxin also activates another MAPK family member, called ERK5, in HeLa cells and in keratinocytes derived from initiated mouse skin (308 cells). By contrast, TPA does not activate ERK5 in these cell lines. The major cell surface receptor for palytoxin is the Na+,K+-ATPase. Accordingly, ouabain blocked the ability of palytoxin to activate ERK5. Ouabain alone did not activate ERK5. ERK5 thus represents a divergence in the signaling pathways activated by these two agents that bind to the Na+,K+-ATPase. Cycloheximide, okadaic acid, and sodium orthovanadate did not mimic the effect of palytoxin on ERK5. These results indicate that the stimulation of ERK5 by palytoxin is not simply due to inhibition of protein synthesis or inhibition of serine/threonine or tyrosine phosphatases. Therefore, the mechanism by which palytoxin activates ERK5 differs from that by which it activates ERK1/2, JNK, and p38. Finally, studies that used pharmacological inhibitors and shRNA to block ERK5 action indicate that ERK5 contributes to palytoxin-stimulated c-Fos gene expression. These results suggest that ERK5 can act as an alternative mediator for transmitting diverse tumor promoter-stimulated signals.

Expression of FLNa in human melanoma cells regulates the function of integrin α1β1 and phosphorylation and localisation of PKB/AKT/ERK1/2 kinases.

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Krebs, Kristi; Ruusmann, Anu; Simonlatser, Grethel; Velling, Teet

2015-12-01

FLNa is a ubiquitous cytoskeletal protein that links transmembrane receptors, including integrins, to F-actin and functions as a signalling intermediate. We investigated FLNa's role in the function of integrin-type collagen receptors, EGF-EGFR signalling and regulation of PKB/Akt and ERK1/2. Using FLNa-deficient M2 human melanoma cells, and same cells expressing EGFP-FLNa (M2F) or its Ig-like repeats 1-8+24, 8-15+24 and 16-24, we found that in M2F and M2 8-15+24 cells, EGF induced the increased phosphorylation of PKB/Akt and ERK1/2. In M2F cells EGF induced the localisation of these kinases to cell nucleus and lamellipodia, respectively, and the ERK1/2 phosphorylation-dependent co-immunoprecipitation of FLNa with ERK1/2. Only M2F and M2 8-15+24 cells adhered to and spread on type I collagen whereas on fibronectin all cells behaved similarly. α1β1 and α2β1 were the integrin-type collagen receptors expressed on these cells with primarily α1β1 localising to focal contacts and affecting cell adhesion and migration in a manner dependent on FLNa or its Ig-like repeats 8-15. Our results suggest a role for FLNa repeats 8-15 in the α1-subunit-dependent regulation of integrin α1β1 function, EGF-EGFR signalling to PKB/Akt and ERK1/2, identify ERK1/2 in EGF-induced FLNa-associated protein complexes, and show that the function of different integrins is subjected to differential regulation by FLNa. Copyright © 2015. Published by Elsevier GmbH.

Didymin Alleviates Hepatic Fibrosis Through Inhibiting ERK and PI3K/Akt Pathways via Regulation of Raf Kinase Inhibitor Protein

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Xing Lin

2016-12-01

Full Text Available Background: Didymin has been reported to have anti-cancer potential. However, the effect of didymin on liver fibrosis remains illdefined. Methods: Hepatic fibrosis was induced by CCl4 in rats. The effects of didymin on liver pathology and collagen accumulation were observed by hematoxylin-eosin and Masson's trichrome staining, respectively. Serum transaminases activities and collagen-related indicators levels were determined by commercially available kits. Moreover, the effects of didymin on hepatic stellate cell apoptosis and cell cycle were analyzed by flow cytometry. Mitochondrial membrane potential was detected by using rhodamine-123 dye. The expression of Raf kinase inhibitor protein (RKIP and the phosphorylation of the ERK/MAPK and PI3K/Akt pathways were assessed by Western blot. Results: Didymin significantly ameliorated chronic liver injury and collagen deposition. It strongly inhibited hepatic stellate cells proliferation, induced apoptosis and caused cell cycle arrest in G2/M phase. Moreover, didymin notably attenuated mitochondrial membrane potential, accompanied by release of cytochrome C. Didymin significantly inhibited the ERK/MAPK and PI3K/Akt pathways. The effects of didymin on the collagen accumulation in rats and on the biological behaviors of hepatic stellate cells were largely abolished by the specific RKIP inhibitor locostatin. Conclusion: Didymin alleviates hepatic fibrosis by inhibiting ERK/MAPK and PI3K/Akt pathways via regulation of RKIP expression.

ERK1/2 mediates glucose-regulated POMC gene expression in hypothalamic neurons.

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Zhang, Juan; Zhou, Yunting; Chen, Cheng; Yu, Feiyuan; Wang, Yun; Gu, Jiang; Ma, Lian; Ho, Guyu

2015-04-01

Hypothalamic glucose-sensing neurons regulate the expression of genes encoding feeding-related neuropetides POMC, AgRP, and NPY - the key components governing metabolic homeostasis. AMP-activated protein kinase (AMPK) is postulated to be the molecular mediator relaying glucose signals to regulate the expression of these neuropeptides. Whether other signaling mediator(s) plays a role is not clear. In this study, we investigated the role of ERK1/2 using primary hypothalamic neurons as the model system. The primary neurons were differentiated from hypothalamic progenitor cells. The differentiated neurons possessed the characteristic neuronal cell morphology and expressed neuronal post-mitotic markers as well as leptin-regulated orexigenic POMC and anorexigenic AgRP/NPY genes. Treatment of cells with glucose dose-dependently increased POMC and decreased AgRP/NPY expression with a concurrent suppression of AMPK phosphorylation. In addition, glucose treatment dose-dependently increased the ERK1/2 phosphorylation. Blockade of ERK1/2 activity with its specific inhibitor PD98059 partially (approximately 50%) abolished glucose-induced POMC expression, but had little effect on AgRP/NPY expression. Conversely, blockade of AMPK activity with its specific inhibitor produced a partial (approximately 50%) reversion of low-glucose-suppressed POMC expression, but almost completely blunted the low-glucose-induced AgRP/NPY expression. The results indicate that ERK1/2 mediated POMC but not AgRP/NPY expression. Confirming the in vitro findings, i.c.v. administration of PD98059 in rats similarly attenuated glucose-induced POMC expression in the hypothalamus, but again had little effect on AgRP/NPY expression. The results are indicative of a novel role of ERK1/2 in glucose-regulated POMC expression and offer new mechanistic insights into hypothalamic glucose sensing. © 2015 Society for Endocrinology.

ERK-dependent and -independent pathways trigger human neural progenitor cell migration

International Nuclear Information System (INIS)

Moors, Michaela; Cline, Jason E.; Abel, Josef; Fritsche, Ellen

2007-01-01

Besides differentiation and apoptosis, cell migration is a basic process in brain development in which neural cells migrate several centimeters within the developing brain before reaching their proper positions and forming the right connections. For identifying signaling events that control neural migration and are therefore potential targets of chemicals to disturb normal brain development, we developed a human neurosphere-based migration assay based on normal human neural progenitor (NHNP) cells, in which the distance is measured that cells wander over time. Applying this assay, we investigated the role of the extracellular signal-regulated kinases 1 and 2 (ERK1/2) in the regulation of NHNP cell migration. Exposure to model substances like ethanol or phorbol 12-myristate 13-acetate (PMA) revealed a correlation between ERK1/2 activation and cell migration. The participation of phospho-(P-) ERK1/2 was confirmed by exposure of the cells to the MEK inhibitor PD98059, which directly prohibits ERK1/2 phosphorylation and inhibited cell migration. We identified protein kinase C (PKC) and epidermal growth factor receptor (EGFR) as upstream signaling kinases governing ERK1/2 activation, thereby controlling NHNP cell migration. Additionally, treatments with src kinase inhibitors led to a diminished cell migration without affecting ERK1/2 phosphorylation. Based on these results, we postulate that migration of NHNP cells is controlled via ERK1/2-dependent and -independent pathways

Activation of ERK mitogen-activated protein kinase in human cells by the mycotoxin patulin

International Nuclear Information System (INIS)

Wu, T.-S.; Yu, F.-Y.; Su, C.-C.; Kan, J.-C.; Chung, C.-P.; Liu, B.-H.

2005-01-01

Patulin (PAT), a mycotoxin produced by certain species of Penicillium and Aspergillus, is often detectable in moldy fruits and their derivative products. PAT led to a concentration-dependent and time-dependent increase in phosphorylation of extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) in human embryonic kidney (HEK293) cells, human peripheral blood mononuclear cells (PBMCs), and Madin-Darby canine kidney (MDCK) cells. Exposure of HEK293 cells to concentrations above 5 μM PAT for 30 min induced ERK1/2 phosphorylation; activation of ERK1/2 was also observed after 24 h incubation with 0.05 μM of PAT. Treatment of human PBMCs for 30 min with 30 μM PAT dramatically increased the phosphorylated ERK1/2 levels. Both MEK1/2 inhibitors, U0126 and PD98059, suppressed ERK1/2 activation in either HEK293 or MDCK cells. In HEK293 cells, U0126-mediated inhibition of PAT-induced ERK1/2 phosphorylation resulted in a significant decrease in levels of DNA damage, expressed as tail moment values, in the single cell gel electrophoresis assay. Conversely, U0126 did not affect cell viability, lactate dehydrogenase release, and the DNA synthesis rate in PAT-treated cultures. Exposure of HEK293 cells for 90 min to 15 μM PAT elevated the levels of early growth response gene-1 (egr-1) mRNA, but not of c-fos, fosB, and junB mRNAs. These results indicate that in human cells, PAT causes a rapid and persistent activation of ERK1/2 and this signaling pathway plays an important role in mediating PAT-induced DNA damage and egr-1 gene expression

Extracellular signal-regulated kinase 2 (ERK-2) mediated phosphorylation regulates nucleo-cytoplasmic shuttling and cell growth control of Ras-associated tumor suppressor protein, RASSF2

International Nuclear Information System (INIS)

Kumari, Gita; Mahalingam, S.

2009-01-01

Ras GTPase controls the normal cell growth through binding with an array of effector molecules, such as Raf and PI3-kinase in a GTP-dependent manner. RASSF2, a member of the Ras association domain family, is known to be involved in the suppression of cell growth and is frequently down-regulated in various tumor tissues by promoter hypermethylation. In the present study, we demonstrate that RASSF2 shuttles between nucleus and cytoplasm by a signal-mediated process and its export from the nucleus is sensitive to leptomycin B. Amino acids between 240 to 260 in the C-terminus of RASSF2 harbor a functional nuclear export signal (NES), which is necessary and sufficient for efficient export of RASSF2 from the nucleus. Substitution of conserved Ile254, Val257 and Leu259 within the minimal NES impaired RASSF2 export from the nucleus. In addition, wild type but not the nuclear export defective RASSF2 mutant interacts with export receptor, CRM-1 and exported from the nucleus. Surprisingly, we observed nucleolar localization for the nuclear export defective mutant suggesting the possibility that RASSF2 may localize in different cellular compartments transiently in a cell cycle dependent manner and the observed nuclear localization for wild type protein may be due to faster export kinetics from the nucleolus. Furthermore, our data suggest that RASSF2 is specifically phosphorylated by MAPK/ERK-2 and the inhibitors of MAPK pathway impair the phosphorylation and subsequently block the export of RASSF2 from the nucleus. These data clearly suggest that ERK-2 mediated phosphorylation plays an important role in regulating the nucleo-cytoplasmic shuttling of RASSF2. Interestingly, nuclear import defective mutant of RASSF2 failed to induce cell cycle arrest at G1/S phase and apoptosis suggesting that RASSF2 regulates cell growth in a nuclear localization dependent manner. Collectively, these data provided evidence for the first time that MAPK/ERK-2 mediated phosphorylation regulates

Extracellular signal-regulated kinase 2 (ERK-2) mediated phosphorylation regulates nucleo-cytoplasmic shuttling and cell growth control of Ras-associated tumor suppressor protein, RASSF2

Energy Technology Data Exchange (ETDEWEB)

Kumari, Gita [Laboratory of Molecular Virology, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500076 (India); Mahalingam, S., E-mail: mahalingam@iitm.ac.in [Laboratory of Molecular Virology, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500076 (India); Department of Biotechnology, Laboratory of Molecular Virology and Cell Biology, Indian Institute of Technology-Madras, Chennai 600 036 (India)

2009-10-01

Ras GTPase controls the normal cell growth through binding with an array of effector molecules, such as Raf and PI3-kinase in a GTP-dependent manner. RASSF2, a member of the Ras association domain family, is known to be involved in the suppression of cell growth and is frequently down-regulated in various tumor tissues by promoter hypermethylation. In the present study, we demonstrate that RASSF2 shuttles between nucleus and cytoplasm by a signal-mediated process and its export from the nucleus is sensitive to leptomycin B. Amino acids between 240 to 260 in the C-terminus of RASSF2 harbor a functional nuclear export signal (NES), which is necessary and sufficient for efficient export of RASSF2 from the nucleus. Substitution of conserved Ile254, Val257 and Leu259 within the minimal NES impaired RASSF2 export from the nucleus. In addition, wild type but not the nuclear export defective RASSF2 mutant interacts with export receptor, CRM-1 and exported from the nucleus. Surprisingly, we observed nucleolar localization for the nuclear export defective mutant suggesting the possibility that RASSF2 may localize in different cellular compartments transiently in a cell cycle dependent manner and the observed nuclear localization for wild type protein may be due to faster export kinetics from the nucleolus. Furthermore, our data suggest that RASSF2 is specifically phosphorylated by MAPK/ERK-2 and the inhibitors of MAPK pathway impair the phosphorylation and subsequently block the export of RASSF2 from the nucleus. These data clearly suggest that ERK-2 mediated phosphorylation plays an important role in regulating the nucleo-cytoplasmic shuttling of RASSF2. Interestingly, nuclear import defective mutant of RASSF2 failed to induce cell cycle arrest at G1/S phase and apoptosis suggesting that RASSF2 regulates cell growth in a nuclear localization dependent manner. Collectively, these data provided evidence for the first time that MAPK/ERK-2 mediated phosphorylation regulates

Telocinobufagin inhibits the epithelial-mesenchymal transition of breast cancer cells through the phosphoinositide 3-kinase/protein kinase B/extracellular signal-regulated kinase/Snail signaling pathway.

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Gao, Yuxue; Shi, Lihong; Cao, Zhen; Zhu, Xuetao; Li, Feng; Wang, Ruyan; Xu, Jinyuan; Zhong, Jinyi; Zhang, Baogang; Lu, Shijun

2018-05-01

Telocinobufagin (TBG), an active ingredient of Venenumbufonis , exhibits an immunomodulatory activity. However, its antimetastatic activity in breast cancer remains unknown. The present study investigated whether TBG prevents breast cancer metastasis and evaluated its regulatory mechanism. TBG inhibited the migration and invasion of 4T1 breast cancer cells. Furthermore, TBG triggered the collapse of F-actin filaments in breast cancer. The epithelial-mesenchymal transition (EMT) markers, vimentin and fibronectin, were downregulated following TBG treatment. However, E-cadherin was upregulated following TBG treatment. Snail, a crucial transcriptional factor of EMT, was downregulated following TBG treatment. Signaling pathway markers, including phosphorylated protein kinase B (P-Akt), p-mechanistic target of rapamycin (mTOR) and p-extracellular signal-regulated kinase (ERK), were decreased following TBG treatment. The same results were obtained from in vivo experiments. In conclusion, in vitro and in vivo experiments reveal that TBG inhibited migration, invasion and EMT via the phosphoinositide 3-kinase (PI3K)/Akt/ERK/Snail signaling pathway in breast cancer.

Proteasome inhibition-induced p38 MAPK/ERK signaling regulates autophagy and apoptosis through the dual phosphorylation of glycogen synthase kinase 3β

International Nuclear Information System (INIS)

Choi, Cheol-Hee; Lee, Byung-Hoon; Ahn, Sang-Gun; Oh, Seon-Hee

2012-01-01

Highlights: ► MG132 induces the phosphorylation of GSK3β Ser9 and, to a lesser extent, of GSK3β Thr390 . ► MG132 induces dephosphorylation of p70S6K Thr389 and phosphorylation of p70S6K Thr421/Ser424 . ► Inactivation of p38 dephosphorylates GSK3β Ser9 and phosphorylates GSK3β Thr390 . ► Inactivation of p38 phosphorylates p70S6K Thr389 and increases the phosphorylation of p70S6K Thr421/Ser424 . ► Inactivation of p38 decreases autophagy and increases apoptosis induced by MG132. -- Abstract: Proteasome inhibition is a promising approach for cancer treatment; however, the underlying mechanisms involved have not been fully elucidated. Here, we show that proteasome inhibition-induced p38 mitogen-activated protein kinase regulates autophagy and apoptosis by modulating the phosphorylation status of glycogen synthase kinase 3β (GSK3β) and 70 kDa ribosomal S6 kinase (p70S6K). The treatment of MDA-MB-231 cells with MG132 induced endoplasmic reticulum stress through the induction of ATF6a, PERK phosphorylation, and CHOP, and apoptosis through the cleavage of Bax and procaspase-3. MG132 caused the phosphorylation of GSK3β at Ser 9 and, to a lesser extent, Thr 390 , the dephosphorylation of p70S6K at Thr 389 , and the phosphorylation of p70S6K at Thr 421 and Ser 424 . The specific p38 inhibitor SB203080 reduced the p-GSK3β Ser9 and autophagy through the phosphorylation of p70S6K Thr389 ; however, it augmented the levels of p-ERK, p-GSK3β Thr390 , and p-70S6K Thr421/Ser424 induced by MG132, and increased apoptotic cell death. The GSK inhibitor SB216763, but not lithium, inhibited the MG132-induced phosphorylation of p38, and the downstream signaling pathway was consistent with that in SB203580-treated cells. Taken together, our data show that proteasome inhibition regulates p38/GSK Ser9 /p70S6K Thr380 and ERK/GSK3β Thr390 /p70S6K Thr421/Ser424 kinase signaling, which is involved in cell survival and cell death.

Biliverdin reductase: more than a namesake - the reductase, its Peptide fragments, and biliverdin regulate activity of the three classes of protein kinase C.

Science.gov (United States)

Gibbs, Peter E M; Tudor, Cicerone; Maines, Mahin D

2012-01-01

The expanse of human biliverdin reductase (hBVR) functions in the cells is arguably unmatched by any single protein. hBVR is a Ser/Thr/Tyr-kinase, a scaffold protein, a transcription factor, and an intracellular transporter of gene regulators. hBVR is an upstream activator of the insulin/IGF-1 signaling pathway and of protein kinase C (PKC) kinases in the two major arms of the pathway. In addition, it is the sole means for generating the antioxidant bilirubin-IXα. hBVR is essential for activation of ERK1/2 kinases by upstream MAPKK-MEK and by PKCδ, as well as the nuclear import and export of ERK1/2. Small fragments of hBVR are potent activators and inhibitors of the ERK kinases and PKCs: as such, they suggest the potential application of BVR-based technology in therapeutic settings. Presently, we have reviewed the function of hBVR in cell signaling with an emphasis on regulation of PKCδ activity.

Inhibition of the ERK phosphorylation plays a role in terbinafine-induced p21 up-regulation and DNA synthesis inhibition in human vascular endothelial cells

International Nuclear Information System (INIS)

Ho, P.-Y.; Hsu, S.-P.; Liang, Y.-C.; Kuo, M.-L.; Ho, Y.-S.; Lee, W.-S.

2008-01-01

Previously, we showed that terbinafine (TB) induces cell-cycle arrest in cultured human umbilical vein endothelial cells (HUVEC) through an up-regulation of the p21 protein. The aim of this study is to delineate the molecular mechanisms underlying TB-induced increase of p21 protein. RT-PCR analysis demonstrated that the mRNA levels of p21 and p53 were increased in the TB-treated HUVEC. The p21 promoter activity was also increased by TB treatment. Transfection of HUVEC with p53 dominant negative (DN) abolished the TB-induced increases of p21 promoter activity and protein level, suggesting that the TB-induced increase of p21 is p53-dependent. Western blot analysis demonstrated that TB decreased the levels of phosphorylated extracellular signal-regulated kinase (ERK). Over-expression of mitogen-activated protein kinase (MEK)-1, the immediate upstream activator kinase of ERK, abolished the TB-induced increases of p21 and p53 protein and decrease of thymidine incorporation. The ERK inhibitor (PD98059) enhanced the TB-induced inhibition of thymidine incorporation into HUVEC. Taken together, these data suggest that the decrease of ERK activity plays a role in the TB-induced up-regulation of p21 in HUVEC. On the other hand, pretreatment of the cells with geranylgeraniol (GGOH), farnesol (FOH), or Ras inhibitor peptide did not affect the TB-induced decrease of thymidine incorporation. Taken together, our results suggest that TB might cause a decrease of MEK, which in turn up-regulates p53 through the inhibition of ERK phosphorylation, and finally causes an increase of p21 expression and cell-cycle arrest

Activation of the Extracellular Signal-Regulated Kinase Signaling Is Critical for Human Umbilical Cord Mesenchymal Stem Cell Osteogenic Differentiation

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Chen-Shuang Li

2016-01-01

Full Text Available Human umbilical cord mesenchymal stem cells (hUCMSCs are recognized as candidate progenitor cells for bone regeneration. However, the mechanism of hUCMSC osteogenesis remains unclear. In this study, we revealed that mitogen-activated protein kinases (MAPKs signaling is involved in hUCMSC osteogenic differentiation in vitro. Particularly, the activation of c-Jun N-terminal kinases (JNK and p38 signaling pathways maintained a consistent level in hUCMSCs through the entire 21-day osteogenic differentiation period. At the same time, the activation of extracellular signal-regulated kinases (ERK signaling significantly increased from day 5, peaked at day 9, and declined thereafter. Moreover, gene profiling of osteogenic markers, alkaline phosphatase (ALP activity measurement, and alizarin red staining demonstrated that the application of U0126, a specific inhibitor for ERK activation, completely prohibited hUCMSC osteogenic differentiation. However, when U0126 was removed from the culture at day 9, ERK activation and osteogenic differentiation of hUCMSCs were partially recovered. Together, these findings demonstrate that the activation of ERK signaling is essential for hUCMSC osteogenic differentiation, which points out the significance of ERK signaling pathway to regulate the osteogenic differentiation of hUCMSCs as an alternative cell source for bone tissue engineering.

ERK2 protein regulates the proliferation of human mesenchymal stem cells without affecting their mobilization and differentiation potential

International Nuclear Information System (INIS)

Carcamo-Orive, Ivan; Tejados, Naiara; Delgado, Jesus; Gaztelumendi, Ainhoa; Otaegui, David; Lang, Valerie; Trigueros, Cesar

2008-01-01

Human Mesenchymal Stem Cells (hMSC), derived mainly from adult bone marrow, are valuable models for the study of processes involved in stem cell self-renewal and differentiation. As the Extracellular signal-Regulated Kinase (ERK) signalling pathway is a major contributor to cellular growth, differentiation and survival, we have studied the functions of this kinase in hMSC activity. Ablation of ERK2 gene expression (but not ERK1) by RNA interference significantly reduced proliferation of hMSC. This reduction was due to a defect in Cyclin D1 expression and subsequent arrest in the G0/G1 phase of the cell cycle. hMSC growth is enhanced through culture medium supplementation with growth factors (GFs) such as Platelet-Derived Growth Factor (PDGF), basic Fibroblast Growth Factor (bFGF) or Epidermal Growth Factor (EGF). However, these supplements could not rescue the defect observed after ERK2 knockdown, suggesting a common signalling pathway used by these GFs for proliferation. In contrast, ERK1/2 may be dissociated from chemotactic signalling induced by the same GFs. Additionally, hMSCs were capable of differentiating into adipocytes even in the absence of either ERK1 or ERK2 proteins. Our data show that hMSCs do not require cell division to enter the adipogenic differentiation process, indicating that clonal amplification of these cells is not a critical step. However, cell-cell contact seems to be an essential requirement to be able to differentiate into mature adipocytes

CSK negatively regulates nerve growth factor induced neural differentiation and augments AKT kinase activity

International Nuclear Information System (INIS)

Dey, Nandini; Howell, Brian W.; De, Pradip K.; Durden, Donald L.

2005-01-01

Src family kinases are involved in transducing growth factor signals for cellular differentiation and proliferation in a variety of cell types. The activity of all Src family kinases (SFKs) is controlled by phosphorylation at their C-terminal 527-tyrosine residue by C-terminal SRC kinase, CSK. There is a paucity of information regarding the role of CSK and/or specific Src family kinases in neuronal differentiation. Pretreatment of PC12 cells with the Src family kinase inhibitor, PP1, blocked NGF-induced activation of SFKs and obliterated neurite outgrowth. To confirm a role for CSK and specific isoforms of SFKs in neuronal differentiation, we overexpressed active and catalytically dead CSK in the rat pheochromocytoma cell line, PC12. CSK overexpression caused a profound inhibition of NGF-induced activation of FYN, YES, RAS, and ERK and inhibited neurite outgrowth, NGF-stimulated integrin-directed migration and blocked the NGF-induced conversion of GDP-RAC to its GTP-bound active state. CSK overexpression markedly augmented the activation state of AKT following NGF stimulation. In contrast, kinase-dead CSK augmented the activation of FYN, RAS, and ERK and increased neurite outgrowth. These data suggest a distinct requirement for CSK in the regulation of NGF/TrkA activation of RAS, RAC, ERK, and AKT via the differential control of SFKs in the orchestration of neuronal differentiation

Interaction with Shc prevents aberrant Erk activation in the absence of extracellular stimuli

KAUST Repository

Suen, KinMan

2013-05-01

Control mechanisms that prevent aberrant signaling are necessary to maintain cellular homeostasis. We describe a new mechanism by which the adaptor protein Shc directly binds the MAP kinase Erk, thus preventing its activation in the absence of extracellular stimuli. The Shc-Erk complex restricts Erk nuclear translocation, restraining Erk-dependent transcription of genes, including those responsible for oncogenic growth. The complex forms through unique binding sites on both the Shc PTB domain and the N-terminal lobe of Erk. Upon receptor tyrosine kinase stimulation, a conformational change within Shc - induced through interaction with the phosphorylated receptor - releases Erk, allowing it to fulfill its role in signaling. Thus, in addition to its established role in promoting MAP kinase signaling in stimulated cells, Shc negatively regulates Erk activation in the absence of growth factors and thus could be considered a tumor suppressor in human cells. © 2013 Nature America, Inc. All rights reserved.

Interaction with Shc prevents aberrant Erk activation in the absence of extracellular stimuli

KAUST Repository

Suen, KinMan; Lin, Chichuan; George, Roger R.; Melo, Fernando A.; Biggs, Eleanor R.; Ahmed, Zamal; Drake, Melanie N.; Arur, Swathi; Arold, Stefan T.; Ladbury, John E S D

2013-01-01

Control mechanisms that prevent aberrant signaling are necessary to maintain cellular homeostasis. We describe a new mechanism by which the adaptor protein Shc directly binds the MAP kinase Erk, thus preventing its activation in the absence of extracellular stimuli. The Shc-Erk complex restricts Erk nuclear translocation, restraining Erk-dependent transcription of genes, including those responsible for oncogenic growth. The complex forms through unique binding sites on both the Shc PTB domain and the N-terminal lobe of Erk. Upon receptor tyrosine kinase stimulation, a conformational change within Shc - induced through interaction with the phosphorylated receptor - releases Erk, allowing it to fulfill its role in signaling. Thus, in addition to its established role in promoting MAP kinase signaling in stimulated cells, Shc negatively regulates Erk activation in the absence of growth factors and thus could be considered a tumor suppressor in human cells. © 2013 Nature America, Inc. All rights reserved.

Biliverdin Reductase: More than a Namesake – The Reductase, Its Peptide Fragments, and Biliverdin Regulate Activity of the Three Classes of Protein Kinase C

Science.gov (United States)

Gibbs, Peter E. M.; Tudor, Cicerone; Maines, Mahin. D.

2012-01-01

The expanse of human biliverdin reductase (hBVR) functions in the cells is arguably unmatched by any single protein. hBVR is a Ser/Thr/Tyr-kinase, a scaffold protein, a transcription factor, and an intracellular transporter of gene regulators. hBVR is an upstream activator of the insulin/IGF-1 signaling pathway and of protein kinase C (PKC) kinases in the two major arms of the pathway. In addition, it is the sole means for generating the antioxidant bilirubin-IXα. hBVR is essential for activation of ERK1/2 kinases by upstream MAPKK-MEK and by PKCδ, as well as the nuclear import and export of ERK1/2. Small fragments of hBVR are potent activators and inhibitors of the ERK kinases and PKCs: as such, they suggest the potential application of BVR-based technology in therapeutic settings. Presently, we have reviewed the function of hBVR in cell signaling with an emphasis on regulation of PKCδ activity. PMID:22419908

Regulation of CCK-induced ERK1/2 activation by PKC epsilon in rat pancreatic acinar cells

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Chenwei Li

2017-11-01

Full Text Available The extracellular signal-regulated kinase ERK1/2 is activated in pancreatic acinar cells by cholecystokinin (CCK and other secretagogues with this activation mediated primarily by protein kinase C (PKC. To identify the responsible PKC isoform, we utilized chemical inhibitors, cell permeant inhibitory peptides and overexpression of individual PKC dominant negative variants by means of adenoviral vectors. While the broad-spectrum PKC inhibitor GF109203X strongly inhibited ERK1/2 activation induced by 100 pM CCK, Go6976 which inhibits the classical PKC isoforms (alpha, beta and gamma, as well as Rottlerin, a specific PKC delta inhibitor, had no inhibitory effect. To test the role of PKC epsilon, we used specific cell permeant peptide inhibitors which block PKC interaction with their intracellular receptors or RACKs. Only PP93 (PKC epsilon peptide inhibitor inhibited CCK-induced ERK1/2 activation, while PP95, PP101 and PP98, which are PKC alpha, delta and zeta peptide inhibitors respectively, had no effect. We also utilized adenovirus to express dominant negative PKC isoforms in pancreatic acini. Only PKC epsilon dominant negative inhibited CCK-induced ERK1/2 activation. Dominant negative PKC epsilon expression similarly blocked the effect of carbachol and bombesin to activate ERK1/2. Immunoprecipitation results demonstrated that CCK can induce an interaction of c-Raf-1 and PKC epsilon, but not that of other isoforms of Raf or PKC. We conclude that PKC epsilon is the isoform of PKC primarily involved with CCK-induced ERK1/2 activation in pancreatic acinar cells.

Phosphorylation of Rac1 T108 by Extracellular Signal-Regulated Kinase in Response to Epidermal Growth Factor: a Novel Mechanism To Regulate Rac1 Function

Science.gov (United States)

Tong, Junfeng; Li, Laiji; Ballermann, Barbara

2013-01-01

Accumulating evidence has implicated Rho GTPases, including Rac1, in many aspects of cancer development. Recent findings suggest that phosphorylation might further contribute to the tight regulation of Rho GTPases. Interestingly, sequence analysis of Rac1 shows that Rac1 T108 within the 106PNTP109 motif is likely an extracellular signal-regulated kinase (ERK) phosphorylation site and that Rac1 also has an ERK docking site, 183KKRKRKCLLL192 (D site), at the C terminus. Indeed, we show here that both transfected and endogenous Rac1 interacts with ERK and that this interaction is mediated by its D site. Green fluorescent protein (GFP)-Rac1 is threonine (T) phosphorylated in response to epidermal growth factor (EGF), and EGF-induced Rac1 threonine phosphorylation is dependent on the activation of ERK. Moreover, mutant Rac1 with the mutation of T108 to alanine (A) is not threonine phosphorylated in response to EGF. In vitro ERK kinase assay further shows that pure active ERK phosphorylates purified Rac1 but not mutant Rac1 T108A. We also show that Rac1 T108 phosphorylation decreases Rac1 activity, partially due to inhibiting its interaction with phospholipase C-γ1 (PLC-γ1). T108 phosphorylation targets Rac1 to the nucleus, which isolates Rac1 from other guanine nucleotide exchange factors (GEFs) and hinders Rac1's role in cell migration. We conclude that Rac1 T108 is phosphorylated by ERK in response to EGF, which plays an important role in regulating Rac1. PMID:24043306

BIG1, a brefeldin A-inhibited guanine nucleotide-exchange protein regulates neurite development via PI3K-AKT and ERK signaling pathways.

Science.gov (United States)

Zhou, C; Li, C; Li, D; Wang, Y; Shao, W; You, Y; Peng, J; Zhang, X; Lu, L; Shen, X

2013-12-19

The elongation of neuron is highly dependent on membrane trafficking. Brefeldin A (BFA)-inhibited guanine nucleotide-exchange protein 1 (BIG1) functions in the membrane trafficking between the Golgi apparatus and the plasma membrane. BFA, an uncompetitive inhibitor of BIG1 can inhibit neurite outgrowth and polarity development. In this study, we aimed to define the possible role of BIG1 in neurite development and to further investigate the potential mechanism. By immunostaining, we found that BIG1 was extensively colocalized with synaptophysin, a marker for synaptic vesicles in soma and partly in neurites. The amount of both protein and mRNA of BIG1 were up-regulated during rat brain development. BIG1 depletion significantly decreased the neurite length and inhibited the phosphorylation of phosphatidylinositide 3-kinase (PI3K) and protein kinase B (AKT). Inhibition of BIG1 guanine nucleotide-exchange factor (GEF) activity by BFA or overexpression of the dominant-negative BIG1 reduced PI3K and AKT phosphorylation, indicating regulatory effects of BIG1 on PI3K-AKT signaling pathway is dependent on its GEF activity. BIG1 siRNA or BFA treatment also significantly reduced extracellular signal-regulated kinase (ERK) phosphorylation. Overexpression of wild-type BIG1 significantly increased ERK phosphorylation, but the dominant-negative BIG1 had no effect on ERK phosphorylation, indicating the involvement of BIG1 in ERK signaling regulation may not be dependent on its GEF activity. Our result identified a novel function of BIG1 in neurite development. The newly recognized function integrates the function of BIG1 in membrane trafficking with the activation of PI3K-AKT and ERK signaling pathways which are critical in neurite development. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

An ERK/Cdk5 axis controls the diabetogenic actions of PPARγ.

Science.gov (United States)

Banks, Alexander S; McAllister, Fiona E; Camporez, João Paulo G; Zushin, Peter-James H; Jurczak, Michael J; Laznik-Bogoslavski, Dina; Shulman, Gerald I; Gygi, Steven P; Spiegelman, Bruce M

2015-01-15

Obesity-linked insulin resistance is a major precursor to the development of type 2 diabetes. Previous work has shown that phosphorylation of PPARγ (peroxisome proliferator-activated receptor γ) at serine 273 by cyclin-dependent kinase 5 (Cdk5) stimulates diabetogenic gene expression in adipose tissues. Inhibition of this modification is a key therapeutic mechanism for anti-diabetic drugs that bind PPARγ, such as the thiazolidinediones and PPARγ partial agonists or non-agonists. For a better understanding of the importance of this obesity-linked PPARγ phosphorylation, we created mice that ablated Cdk5 specifically in adipose tissues. These mice have both a paradoxical increase in PPARγ phosphorylation at serine 273 and worsened insulin resistance. Unbiased proteomic studies show that extracellular signal-regulated kinase (ERK) kinases are activated in these knockout animals. Here we show that ERK directly phosphorylates serine 273 of PPARγ in a robust manner and that Cdk5 suppresses ERKs through direct action on a novel site in MAP kinase/ERK kinase (MEK). Importantly, pharmacological inhibition of MEK and ERK markedly improves insulin resistance in both obese wild-type and ob/ob mice, and also completely reverses the deleterious effects of the Cdk5 ablation. These data show that an ERK/Cdk5 axis controls PPARγ function and suggest that MEK/ERK inhibitors may hold promise for the treatment of type 2 diabetes.

Resveratrol upregulates Egr-1 expression and activity involving extracellular signal-regulated protein kinase and ternary complex factors

Energy Technology Data Exchange (ETDEWEB)

Rössler, Oliver G.; Glatzel, Daniel; Thiel, Gerald, E-mail: gerald.thiel@uks.eu

2015-03-01

Many intracellular functions have been attributed to resveratrol, a polyphenolic phytoalexin found in grapes and in other plants. Here, we show that resveratrol induces the expression of the transcription factor Egr-1 in human embryonic kidney cells. Using a chromosomally embedded Egr-1-responsive reporter gene, we show that the Egr-1 activity was significantly elevated in resveratrol-treated cells, indicating that the newly synthesized Egr-1 protein was biologically active. Stimulus-transcription coupling leading to the resveratrol-induced upregulation of Egr-1 expression and activity requires the protein kinases Raf and extracellular signal-regulated protein kinase ERK, while MAP kinase phosphatase-1 functions as a nuclear shut-off device that interrupts the signaling cascade connecting resveratrol stimulation with enhanced Egr-1 expression. On the transcriptional level, Elk-1, a key transcriptional regulator of serum response element-driven gene transcription, connects the intracellular signaling cascade elicited by resveratrol with transcription of the Egr-1 gene. These data were corroborated by the observation that stimulation of the cells with resveratrol increased the transcriptional activation potential of Elk-1. The SRE as well as the GC-rich DNA binding site of Egr-1 function as resveratrol-responsive elements. Thus, resveratrol regulates gene transcription via activation of the stimulus-regulated protein kinases Raf and ERK and the stimulus-responsive transcription factors TCF and Egr-1. - Highlights: • The plant polyphenol resveratrol upregulates Egr-1 expression and activity. • The stimulation of Egr-1 requires the protein kinases ERK and Raf. • Resveratrol treatment upregulates the transcriptional activation potential of Elk-1. • Resveratrol-induced stimulation of Egr-1 requires ternary complex factors. • Two distinct resveratrol-responsive elements were identified.

Resveratrol upregulates Egr-1 expression and activity involving extracellular signal-regulated protein kinase and ternary complex factors

International Nuclear Information System (INIS)

Rössler, Oliver G.; Glatzel, Daniel; Thiel, Gerald

2015-01-01

Many intracellular functions have been attributed to resveratrol, a polyphenolic phytoalexin found in grapes and in other plants. Here, we show that resveratrol induces the expression of the transcription factor Egr-1 in human embryonic kidney cells. Using a chromosomally embedded Egr-1-responsive reporter gene, we show that the Egr-1 activity was significantly elevated in resveratrol-treated cells, indicating that the newly synthesized Egr-1 protein was biologically active. Stimulus-transcription coupling leading to the resveratrol-induced upregulation of Egr-1 expression and activity requires the protein kinases Raf and extracellular signal-regulated protein kinase ERK, while MAP kinase phosphatase-1 functions as a nuclear shut-off device that interrupts the signaling cascade connecting resveratrol stimulation with enhanced Egr-1 expression. On the transcriptional level, Elk-1, a key transcriptional regulator of serum response element-driven gene transcription, connects the intracellular signaling cascade elicited by resveratrol with transcription of the Egr-1 gene. These data were corroborated by the observation that stimulation of the cells with resveratrol increased the transcriptional activation potential of Elk-1. The SRE as well as the GC-rich DNA binding site of Egr-1 function as resveratrol-responsive elements. Thus, resveratrol regulates gene transcription via activation of the stimulus-regulated protein kinases Raf and ERK and the stimulus-responsive transcription factors TCF and Egr-1. - Highlights: • The plant polyphenol resveratrol upregulates Egr-1 expression and activity. • The stimulation of Egr-1 requires the protein kinases ERK and Raf. • Resveratrol treatment upregulates the transcriptional activation potential of Elk-1. • Resveratrol-induced stimulation of Egr-1 requires ternary complex factors. • Two distinct resveratrol-responsive elements were identified

Eotaxin induces degranulation and chemotaxis of eosinophils through the activation of ERK2 and p38 mitogen-activated protein kinases

DEFF Research Database (Denmark)

Kampen, G T; Stafford, S; Adachi, T

2000-01-01

Eotaxin and other CC chemokines acting via CC chemokine receptor-3 (CCR3) are believed to play an integral role in the development of eosinophilic inflammation in asthma and allergic inflammatory diseases. However, little is known about the intracellular events following agonist binding to CCR3...... and the relationship of these events to the functional response of the cell. The objectives of this study were to investigate CCR3-mediated activation of the mitogen-activated protein (MAP) kinases extracellular signal-regulated kinase-2 (ERK2), p38, and c-jun N-terminal kinase (JNK) in eosinophils and to assess...... the requirement for MAP kinases in eotaxin-induced eosinophil cationic protein (ECP) release and chemotaxis. MAP kinase activation was studied in eotaxin-stimulated eosinophils (more than 97% purity) by Western blotting and immune-complex kinase assays. ECP release was measured by radioimmunoassay. Chemotaxis...

p53- and ERK7-dependent ribosome surveillance response regulates Drosophila insulin-like peptide secretion.

Directory of Open Access Journals (Sweden)

Kiran Hasygar

2014-11-01

Full Text Available Insulin-like signalling is a conserved mechanism that coordinates animal growth and metabolism with nutrient status. In Drosophila, insulin-producing median neurosecretory cells (IPCs regulate larval growth by secreting insulin-like peptides (dILPs in a diet-dependent manner. Previous studies have shown that nutrition affects dILP secretion through humoral signals derived from the fat body. Here we uncover a novel mechanism that operates cell autonomously in the IPCs to regulate dILP secretion. We observed that impairment of ribosome biogenesis specifically in the IPCs strongly inhibits dILP secretion, which consequently leads to reduced body size and a delay in larval development. This response is dependent on p53, a known surveillance factor for ribosome biogenesis. A downstream effector of this growth inhibitory response is an atypical MAP kinase ERK7 (ERK8/MAPK15, which is upregulated in the IPCs following impaired ribosome biogenesis as well as starvation. We show that ERK7 is sufficient and essential to inhibit dILP secretion upon impaired ribosome biogenesis, and it acts epistatically to p53. Moreover, we provide evidence that p53 and ERK7 contribute to the inhibition of dILP secretion upon starvation. Thus, we conclude that a cell autonomous ribosome surveillance response, which leads to upregulation of ERK7, inhibits dILP secretion to impede tissue growth under limiting dietary conditions.

Loss of Extracellular Signal-Regulated Kinase 1/2 in the Retinal Pigment Epithelium Leads to RPE65 Decrease and Retinal Degeneration.

Science.gov (United States)

Pyakurel, Aswin; Balmer, Delphine; Saba-El-Leil, Marc K; Kizilyaprak, Caroline; Daraspe, Jean; Humbel, Bruno M; Voisin, Laure; Le, Yun Z; von Lintig, Johannes; Meloche, Sylvain; Roduit, Raphaël

2017-12-15

Recent work suggested that the activity of extracellular signal-regulated kinase 1/2 (ERK1/2) is increased in the retinal pigment epithelium (RPE) of age-related macular degeneration (ARMD) patients and therefore could be an attractive therapeutic target. Notably, ERK1/2 pathway inhibitors are used in cancer therapy, with severe and noncharacterized ocular side effects. To decipher the role of ERK1/2 in RPE cells, we conditionally disrupted the Erk1 and Erk2 genes in mouse RPE. The loss of ERK1/2 activity resulted in a significant decrease in the level of RPE65 expression, a decrease in ocular retinoid levels concomitant with low visual function, and a rapid disorganization of RPE cells, ultimately leading to retinal degeneration. Our results identify the ERK1/2 pathway as a direct regulator of the visual cycle and a critical component of the viability of RPE and photoreceptor cells. Moreover, our results caution about the need for a very fine adjustment of kinase inhibition in cancer or ARMD treatment in order to avoid ocular side effects. Copyright © 2017 Pyakurel et al.

The ERK5 and ERK1/2 signaling pathways play opposing regulatory roles during chondrogenesis of adult human bone marrow-derived multipotent progenitor cells.

Science.gov (United States)

Bobick, Brent E; Matsche, Alexander I; Chen, Faye H; Tuan, Rocky S

2010-07-01

Adult human bone marrow-derived multipotent progenitor cells (MPCs) are able to differentiate into a variety of specialized cell types, including chondrocytes, and are considered a promising candidate cell source for use in cartilage tissue engineering. In this study, we examined the regulation of MPC chondrogenesis by mitogen-activated protein kinases in an attempt to better understand how to generate hyaline cartilage in the laboratory that more closely resembles native tissue. Specifically, we employed the high-density pellet culture model system to assess the roles of ERK5 and ERK1/2 pathway signaling in MPC chondrogenesis. Western blotting revealed that high levels of ERK5 phosphorylation correlate with low levels of MPC chondrogenesis and that as TGF-beta 3-enhanced MPC chondrogenesis proceeds, phospho-ERK5 levels steadily decline. Conversely, levels of phospho-ERK1/2 paralleled the progression of MPC chondrogenesis. siRNA-mediated knockdown of ERK5 pathway components MEK5 and ERK5 resulted in increased MPC pellet mRNA transcript levels of the cartilage-characteristic marker genes SOX9, COL2A1, AGC, L-SOX5, and SOX6, as well as enhanced accumulation of SOX9 protein, collagen type II protein, and Alcian blue-stainable proteoglycan. In contrast, knockdown of ERK1/2 pathway members MEK1 and ERK1 decreased expression of all chondrogenic markers tested. Finally, overexpression of MEK5 and ERK5 also depressed MPC chondrogenesis, as indicated by diminished activity of a co-transfected collagen II promoter-luciferase reporter construct. In conclusion, our results suggest a novel role for the ERK5 pathway as an important negative regulator of adult human MPC chondrogenesis and illustrate that the ERK5 and ERK1/2 kinase cascades play opposing roles regulating MPC cartilage formation. (c) 2010 Wiley-Liss, Inc.

Primate Torpor: Regulation of Stress-activated Protein Kinases During Daily Torpor in the Gray Mouse Lemur, Microcebus murinus

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Kyle K. Biggar

2015-04-01

Full Text Available Very few selected species of primates are known to be capable of entering torpor. This exciting discovery means that the ability to enter a natural state of dormancy is an ancestral trait among primates and, in phylogenetic terms, is very close to the human lineage. To explore the regulatory mechanisms that underlie primate torpor, we analyzed signal transduction cascades to discover those involved in coordinating tissue responses during torpor. The responses of mitogen-activated protein kinase (MAPK family members to primate torpor were compared in six organs of control (aroused versus torpid gray mouse lemurs, Microcebus murinus. The proteins examined include extracellular signal-regulated kinases (ERKs, c-jun NH2-terminal kinases (JNKs, MAPK kinase (MEK, and p38, in addition to stress-related proteins p53 and heat shock protein 27 (HSP27. The activation of specific MAPK signal transduction pathways may provide a mechanism to regulate the expression of torpor-responsive genes or the regulation of selected downstream cellular processes. In response to torpor, each MAPK subfamily responded differently during torpor and each showed organ-specific patterns of response. For example, skeletal muscle displayed elevated relative phosphorylation of ERK1/2 during torpor. Interestingly, adipose tissues showed the highest degree of MAPK activation. Brown adipose tissue displayed an activation of ERK1/2 and p38, whereas white adipose tissue showed activation of ERK1/2, p38, MEK, and JNK during torpor. Importantly, both adipose tissues possess specialized functions that are critical for torpor, with brown adipose required for non-shivering thermogenesis and white adipose utilized as the primary source of lipid fuel for torpor. Overall, these data indicate crucial roles of MAPKs in the regulation of primate organs during torpor.

Proteasome inhibition-induced p38 MAPK/ERK signaling regulates autophagy and apoptosis through the dual phosphorylation of glycogen synthase kinase 3{beta}

Energy Technology Data Exchange (ETDEWEB)

Choi, Cheol-Hee [Research Center for Resistant Cells, Chosun University, Seosuk-dong, Dong-gu, Gwangju 501-759 (Korea, Republic of); Department of Pharmacology, College of Medicine, Chosun University, Seosuk-dong, Dong-gu, Gwangju 501-759 (Korea, Republic of); Lee, Byung-Hoon [College of Pharmacy and Multiscreening Center for Drug Development, Seoul National University, Seoul 151-742 (Korea, Republic of); Ahn, Sang-Gun [Department of Pathology, College of Dentistry, Chosun University, Gwangju 501-759 (Korea, Republic of); Oh, Seon-Hee, E-mail: oshccw@hanmail.net [Research Center for Resistant Cells, Chosun University, Seosuk-dong, Dong-gu, Gwangju 501-759 (Korea, Republic of)

2012-02-24

Highlights: Black-Right-Pointing-Pointer MG132 induces the phosphorylation of GSK3{beta}{sup Ser9} and, to a lesser extent, of GSK3{beta}{sup Thr390}. Black-Right-Pointing-Pointer MG132 induces dephosphorylation of p70S6K{sup Thr389} and phosphorylation of p70S6K{sup Thr421/Ser424}. Black-Right-Pointing-Pointer Inactivation of p38 dephosphorylates GSK3{beta}{sup Ser9} and phosphorylates GSK3{beta}{sup Thr390}. Black-Right-Pointing-Pointer Inactivation of p38 phosphorylates p70S6K{sup Thr389} and increases the phosphorylation of p70S6K{sup Thr421/Ser424}. Black-Right-Pointing-Pointer Inactivation of p38 decreases autophagy and increases apoptosis induced by MG132. -- Abstract: Proteasome inhibition is a promising approach for cancer treatment; however, the underlying mechanisms involved have not been fully elucidated. Here, we show that proteasome inhibition-induced p38 mitogen-activated protein kinase regulates autophagy and apoptosis by modulating the phosphorylation status of glycogen synthase kinase 3{beta} (GSK3{beta}) and 70 kDa ribosomal S6 kinase (p70S6K). The treatment of MDA-MB-231 cells with MG132 induced endoplasmic reticulum stress through the induction of ATF6a, PERK phosphorylation, and CHOP, and apoptosis through the cleavage of Bax and procaspase-3. MG132 caused the phosphorylation of GSK3{beta} at Ser{sup 9} and, to a lesser extent, Thr{sup 390}, the dephosphorylation of p70S6K at Thr{sup 389}, and the phosphorylation of p70S6K at Thr{sup 421} and Ser{sup 424}. The specific p38 inhibitor SB203080 reduced the p-GSK3{beta}{sup Ser9} and autophagy through the phosphorylation of p70S6K{sup Thr389}; however, it augmented the levels of p-ERK, p-GSK3{beta}{sup Thr390}, and p-70S6K{sup Thr421/Ser424} induced by MG132, and increased apoptotic cell death. The GSK inhibitor SB216763, but not lithium, inhibited the MG132-induced phosphorylation of p38, and the downstream signaling pathway was consistent with that in SB203580-treated cells. Taken together, our

The D Domain of LRRC4 anchors ERK1/2 in the cytoplasm and competitively inhibits MEK/ERK activation in glioma cells

Directory of Open Access Journals (Sweden)

Zeyou Wang

2016-11-01

Full Text Available Abstract Background As a well-characterized key player in various signal transduction networks, extracellular-signal-regulated kinase (ERK1/2 has been widely implicated in the development of many malignancies. We previously found that Leucine-rich repeat containing 4 (LRRC4 was a tumor suppressor and a negative regulator of the ERK/MAPK pathway in glioma tumorigenesis. However, the precise molecular role of LRRC4 in ERK signal transmission is unclear. Methods The interaction between LRRC4 and ERK1/2 was assessed by co-immunoprecipitation and GST pull-down assays in vivo and in vitro. We also investigated the interaction of LRRC4 and ERK1/2 and the role of the D domain in ERK activation in glioma cells. Results Here, we showed that LRRC4 and ERK1/2 interact via the D domain and CD domain, respectively. Following EGF stimuli, the D domain of LRRC4 anchors ERK1/2 in the cytoplasm and abrogates ERK1/2 activation and nuclear translocation. In glioblastoma cells, ectopic LRRC4 expression competitively inhibited the interaction of endogenous mitogen-activated protein kinase (MEK and ERK1/2. Mutation of the D domain decreased the LRRC4-mediated inhibition of MAPK signaling and its anti-proliferation and anti-invasion roles. Conclusions Our results demonstrated that the D domain of LRRC4 anchors ERK1/2 in the cytoplasm and competitively inhibits MEK/ERK activation in glioma cells. These findings identify a new mechanism underlying glioblastoma progression and suggest a novel therapeutic strategy by restoring the activity of LRRC4 to decrease MAPK cascade activation.

Mesenchymal stem cells cultured under hypoxia escape from senescence via down-regulation of p16 and extracellular signal regulated kinase

International Nuclear Information System (INIS)

Jin, Yonghui; Kato, Tomohisa; Furu, Moritoshi; Nasu, Akira; Kajita, Yoichiro; Mitsui, Hiroto; Ueda, Michiko; Aoyama, Tomoki; Nakayama, Tomitaka; Nakamura, Takashi; Toguchida, Junya

2010-01-01

Hypoxia has been considered to affect the properties of tissue stem cells including mesenchymal stem cells (MSCs). Effects of long periods of exposure to hypoxia on human MSCs, however, have not been clearly demonstrated. MSCs cultured under normoxic conditions (20% pO 2 ) ceased to proliferate after 15-25 population doublings, while MSCs cultured under hypoxic conditions (1% pO 2 ) retained the ability to proliferate with an additional 8-20 population doublings. Most of the MSCs cultured under normoxic conditions were in a senescent state after 100 days, while few senescent cells were found in the hypoxic culture, which was associated with a down-regulation of p16 gene expression. MSCs cultured for 100 days under hypoxic conditions were superior to those cultured under normoxic conditions in the ability to differentiate into the chondro- and adipogenic, but not osteogenic, lineage. Among the molecules related to mitogen-activated protein kinase (MAPK) signaling pathways, extracellular signal regulated kinase (ERK) was significantly down-regulated by hypoxia, which helped to inhibit the up-regulation of p16 gene expression. Therefore, the hypoxic culture retained MSCs in an undifferentiated and senescence-free state through the down-regulation of p16 and ERK.

Validation of commercial ERK antibodies against the ERK orthologue of the scleractinian coral Stylophora pistillata [version 1; referees: 1 approved, 2 approved with reservations

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Lucile Courtial

2017-04-01

Full Text Available The extracellular signal-regulated protein kinase (ERK signalling pathway controls key cellular processes, such as cell cycle regulation, cell fate determination and the response to external stressors. Although ERK functions are well studied in a variety of living organisms ranging from yeast to mammals, its functions in corals are still poorly known. The present work aims to give practical tools to study the expression level of ERK protein and the activity of the ERK signalling pathway in corals. The antibody characterisation experiment was performed five times and identical results were obtained. The present study validated the immune-reactivity of commercially available antibodies directed against ERK and its phosphorylated/activated forms on protein extracts of the reef-building coral Stylophora pistillata.

Ubiquitin carboxyl terminal hydrolase L1 negatively regulates TNFα-mediated vascular smooth muscle cell proliferation via suppressing ERK activation

International Nuclear Information System (INIS)

Ichikawa, Tomonaga; Li, Jinqing; Dong, Xiaoyu; Potts, Jay D.; Tang, Dong-Qi; Li, Dong-Sheng; Cui, Taixing

2010-01-01

Deubiquitinating enzymes (DUBs) appear to be critical regulators of a multitude of processes such as proliferation, apoptosis, differentiation, and inflammation. We have recently demonstrated that a DUB of ubiquitin carboxyl terminal hydrolase L1 (UCH-L1) inhibits vascular lesion formation via suppressing inflammatory responses in vasculature. However, the precise underlying mechanism remains to be defined. Herein, we report that a posttranscriptional up-regulation of UCH-L1 provides a negative feedback to tumor necrosis factor alpha (TNFα)-mediated activation of extracellular signal-regulated kinases (ERK) and proliferation in vascular smooth muscle cells (VSMCs). In rat adult VSMCs, adenoviral over-expression of UCH-L1 inhibited TNFα-induced activation of ERK and DNA synthesis. In contrast, over-expression of UCH-L1 did not affect platelet derived growth factor (PDGF)-induced VSMC proliferation and activation of growth stimulating cascades including ERK. TNFα hardly altered UCH-L1 mRNA expression and stability; however, up-regulated UCH-L1 protein expression via increasing UCH-L1 translation. These results uncover a novel mechanism by which UCH-L1 suppresses vascular inflammation.

Regulation of Schistosoma mansoni development and reproduction by the mitogen-activated protein kinase signaling pathway.

Science.gov (United States)

Andrade, Luiza Freire de; Mourão, Marina de Moraes; Geraldo, Juliana Assis; Coelho, Fernanda Sales; Silva, Larissa Lopes; Neves, Renata Heisler; Volpini, Angela; Machado-Silva, José Roberto; Araujo, Neusa; Nacif-Pimenta, Rafael; Caffrey, Conor R; Oliveira, Guilherme

2014-06-01

Protein kinases are proven targets for drug development with an increasing number of eukaryotic Protein Kinase (ePK) inhibitors now approved as drugs. Mitogen-activated protein kinase (MAPK) family members connect cell-surface receptors to regulatory targets within cells and influence a number of tissue-specific biological activities such as cell proliferation, differentiation and survival. However, the contributions of members of the MAPK pathway to schistosome development and survival are unclear. We employed RNA interference (RNAi) to elucidate the functional roles of five S. mansoni genes (SmCaMK2, SmJNK, SmERK1, SmERK2 and SmRas) involved in MAPK signaling pathway. Mice were injected with post-infective larvae (schistosomula) subsequent to RNAi and the development of adult worms observed. The data demonstrate that SmJNK participates in parasite maturation and survival of the parasites, whereas SmERK are involved in egg production as infected mice had significantly lower egg burdens with female worms presenting underdeveloped ovaries. Furthermore, it was shown that the c-fos transcription factor was overexpressed in parasites submitted to RNAi of SmERK1, SmJNK and SmCaMK2 indicating its putative involvement in gene regulation in this parasite's MAPK signaling cascade. We conclude that MAPKs proteins play important roles in the parasite in vivo survival, being essential for normal development and successful survival and reproduction of the schistosome parasite. Moreover SmERK and SmJNK are potential targets for drug development.

Analgesic effect of paeoniflorin in rats with neonatal maternal separation-induced visceral hyperalgesia is mediated through adenosine A(1) receptor by inhibiting the extracellular signal-regulated protein kinase (ERK) pathway.

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Zhang, Xiao-Jun; Chen, Hong-Li; Li, Zhi; Zhang, Hong-Qi; Xu, Hong-Xi; Sung, Joseph J Y; Bian, Zhao-Xiang

2009-11-01

Paeoniflorin (PF), a chief active ingredient in the root of Paeonia lactiflora Pall (family Ranunculaceae), is effective in relieving colorectal distention (CRD)-induced visceral pain in rats with visceral hyperalgesia induced by neonatal maternal separation (NMS). This study aimed at exploring the underlying mechanisms of PF's analgesic effect on CRD-evoked nociceptive signaling in the central nervous system (CNS) and investigating whether the adenosine A(1) receptor is involved in PF's anti-nociception. CRD-induced visceral pain as well as phosphorylated-extracellular signal-regulated protein kinase (p-ERK) and phospho-cAMP response element-binding protein (p-CREB) expression in the CNS structures of NMS rats were suppressed by NMDA receptor antagonist dizocilpine (MK-801) and ERK phosphorylation inhibitor U0126. PF could similarly inhibit CRD-evoked p-ERK and c-Fos expression in laminae I-II of the lumbosacral dorsal horn and anterior cingulate cortex (ACC). PF could also reverse the CRD-evoked increased glutamate concentration by CRD as shown by dynamic microdialysis monitoring in ACC, whereas, DPCPX, an antagonist of adenosine A(1) receptor, significantly blocked the analgesic effect of PF and PF's inhibition on CRD-induced p-ERK and p-CREB expression. These results suggest that PF's analgesic effect is possibly mediated by adenosine A(1) receptor by inhibiting CRD-evoked glutamate release and the NMDA receptor dependent ERK signaling.

Activated Fps/Fes tyrosine kinase regulates erythroid differentiation and survival.

Science.gov (United States)

Sangrar, Waheed; Gao, Yan; Bates, Barbara; Zirngibl, Ralph; Greer, Peter A

2004-10-01

A substantial body of evidence implicates the cytoplasmic protein tyrosine kinase Fps/Fes in regulation of myeloid differentiation and survival. In this study we wished to determine if Fps/Fes also plays a role in the regulation of erythropoiesis. Mice tissue-specifically expressing a "gain-of-function" mutant fps/fes transgene (fps(MF)) encoding an activated variant of Fps/Fes (MFps), were used to explore the in vivo biological role of Fps/Fes. Erythropoiesis in these mice was assessed by hematological analysis, lineage marker analysis, bone-marrow colony assays, and biochemical approaches. fps(MF) mice displayed reductions in peripheral red cell counts. However, there was an accumulation of immature erythroid precursors, which displayed increased survival. Fps/Fes and the related Fer kinase were both detected in early erythroid progenitors/blasts and in mature red cells. Fps/Fes was also activated in response to erythropoietin (EPO) and stem cell factor (SCF), two critical factors in erythroid development. In addition, increased Stat5A/B activation and reduced Erk1/2 phosphorylation was observed in fps(MF) primary erythroid cells in response to EPO or SCF, respectively. These data support a role for Fps/Fes in regulating the survival and differentiation of erythroid cells through modulation of Stat5A/B and Erk kinase pathways induced by EPO and SCF. The increased numbers and survival of erythroid progenitors from fps(MF) mice, and their differential responsiveness to SCF and EPO, implicates Fps/Fes in the commitment of multilineage progenitors to the erythroid lineage. The anemic phenotype in fps(MF) mice suggests that downregulation of Fps/Fes activity might be required for terminal erythroid differentiation.

Different Expression of Extracellular Signal-Regulated Kinases (ERK) 1/2 and Phospho-Erk Proteins in MBA-MB-231 and MCF-7 Cells after Chemotherapy with Doxorubicin or Docetaxel.

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Taherian, Aliakbar; Mazoochi, Tahereh

2012-01-01

Curative treatment of breast cancer patients using chemotherapy often fails as a result of intrinsic or acquired resistance of the tumor to the drug. ERK is one of the main components of the Ras/Raf/MEK/ERK cascade, which mediates signal from cell surface receptors to transcription factors to regulate different gene expression. In this study, cytotoxicity and the expression of Erk1/2 and phospho-ERK was compared in MDA-MB-231 (ER-) and MCF-7 (ER+) cell lines after treatment with doxorubicin (DOX) or docetaxel (DOCT). Cell cytotoxicity of DOX or DOCT was calculated using MTT assay. Immonofluorescent technique was used to show MDR-1 protein in MDA-MB-231 and MCF-7 cells after treatment with DOX or DOCT. The expression of ERK1/2 and phpspho-ERK was assayed with immunoblotting. Comparing IC50 values showed that MDA-MB-231 cells are more sensitive than MCF-7 cells to DOX or DOCT. Immonofluorescent results confirmed the expression of MDR-1 in these two cell lines after DOX or DOCT treatment. In MDA-MB-231 cells the expression of ERK1/2 and phospho-ERK was decreased after DOX treatment in a dose-dependent manner. In contrast in MCF-7 cells the expression of ERK1/2 and phospho-ERK was increased after DOX treatment. DOCT treatment demonstrated the same result with less significant differences than DOX. The heterogeneity seen in cell lines actually reflects the heterogeneity of breast cancers. That is why, patients categorized in one group respond differently to a single treatment. These results emphasize the importance of a more accurate classification and a more specific treatment of breast cancer subtypes.

The MAPK ERK5, but not ERK1/2, inhibits the progression of monocytic phenotype to the functioning macrophage

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Wang, Xuening [Department of Pathology and Laboratory Medicine, Rutgers, NJ Medical School, 185 South Orange Ave, Newark, NJ 07103 (United States); Pesakhov, Stella [Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, PO Box 653, 84105 Beer-Sheva (Israel); Harrison, Jonathan S [Department of Medicine, Rutgers, Robert Wood Johnson Medical School, New Brunswick, NJ 08903 (United States); Kafka, Michael; Danilenko, Michael [Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, PO Box 653, 84105 Beer-Sheva (Israel); Studzinski, George P, E-mail: studzins@njms.rutgers.edu [Department of Pathology and Laboratory Medicine, Rutgers, NJ Medical School, 185 South Orange Ave, Newark, NJ 07103 (United States)

2015-01-01

Intracellular signaling pathways present targets for pharmacological agents with potential for treatment of neoplastic diseases, with some disease remissions already recorded. However, cellular compensatory mechanisms usually negate the initial success. For instance, attempts to interrupt aberrant signaling downstream of the frequently mutated ras by inhibiting ERK1/2 has shown only limited usefulness for cancer therapy. Here, we examined how ERK5, that overlaps the functions of ERK1/2 in cell proliferation and survival, functions in a manner distinct from ERK1/2 in human AML cells induced to differentiate by 1,25D-dihydroxyvitamin D{sub 3} (1,25D). Using inhibitors of ERK1/2 and of MEK5/ERK5 at concentrations specific for each kinase in HL60 and U937 cells, we observed that selective inhibition of the kinase activity of ERK5, but not of ERK1/2, in the presence of 1,25D resulted in macrophage-like cell morphology and enhancement of phagocytic activity. Importantly, this was associated with increased expression of the macrophage colony stimulating factor receptor (M-CSFR), but was not seen when M-CSFR expression was knocked down. Interestingly, inhibition of ERK1/2 led to activation of ERK5 in these cells. Our results support the hypothesis that ERK5 negatively regulates the expression of M-CSFR, and thus has a restraining function on macrophage differentiation. The addition of pharmacological inhibitors of ERK5 may influence trials of differentiation therapy of AML. - Highlights: • ERK5 has at least some functions in AML cells which are distinct from those of ERK1/2. • ERK5 activity negatively controls the expression of M-CSFR. • ERK5 retards the progression of differentiation from monocyte to functional macrophage.

Urotensin II contributes to collagen synthesis and up-regulates Egr-1 expression in cultured pulmonary arterial smooth muscle cells through the ERK1/2 pathway

Energy Technology Data Exchange (ETDEWEB)

Li, Wei [Biomedical Engineering Institute, School of Control Science and Engineering, Shandong University, Jinan 250061 (China); Cai, Zhifeng; Liu, Mengmeng [Department of Pediatrics, Qilu Hospital, Shandong University, Jinan 250012 (China); Zhao, Cuifen, E-mail: zhaocuifen@sdu.edu.cn [Department of Pediatrics, Qilu Hospital, Shandong University, Jinan 250012 (China); Li, Dong [Research Room of Hypothermia Medicine, Qilu Hospital, Shandong University, Jinan 250012 (China); Lv, Chenguang; Wang, Yuping; Xu, Tengfei [Biomedical Engineering Institute, School of Control Science and Engineering, Shandong University, Jinan 250061 (China)

2015-11-27

Aim: The objective of this study was to investigate the effects of urotensin II (UII) treatment on the proliferation and collagen synthesis of cultured rat pulmonary arterial smooth muscle cells (PASMCs) and to explore whether these effects are mediated by mitogen-activated protein kinase (MAPK) signaling pathways and early growth response 1 (Egr-1). Methods: The proliferation of cultured PASMCs stimulated with different doses of UII was detected by BrdU incorporation. The mRNA expression levels of procollagen I (procol I), procollagen III (procol III), extracellular regulated protein kinase 1/2 (ERK1/2), stress-stimulated protein kinase (Sapk), p38 MAPK (p38), and Egr-1 mRNA in cultured PASMCs after treatment with UII, the UII-specific antagonist urantide, and the ERK1/2 inhibitor PD98059 were detected by real-time polymerase chain reaction (PCR), and the protein expression levels of procol I, procol III, phosphorylated (p)-ERK1/2, p-Sapk, p-p38, and Egr-1 were detected by Western blotting. Results: Treatment with UII increased the proliferation of cultured PASMCs in a dose-dependent manner (P < 0.05). However, treatment with urantide and PD98059 inhibited the promoting effect of UII on PASMC proliferation (P < 0.05). Real-time PCR analysis showed that UII up-regulated the expression of procol I, procol III, ERK1/2, Sapk, and Egr-1 mRNA (P < 0.05), but not p38 mRNA. However, the up-regulating effect of UII was inhibited by PD98059 and urantide. Western blotting analysis showed that UII increased the synthesis of collagen I, collagen III, p-ERK1/2, p-Sapk, and Egr-1, and these effects also were inhibited by PD98059 and urantide (P < 0.05). Conclusions: Egr-1 participates in the UII-mediated proliferation and collagen synthesis of cultured rat PASMCs via activation of the ERK1/2 signaling pathway.

Extracellular signal-regulated kinase activation is required for consolidation and reconsolidation of memory at an early stage of ontogenesis.

Science.gov (United States)

Languille, Solène; Davis, Sabrina; Richer, Paulette; Alcacer, Cristina; Laroche, Serge; Hars, Bernard

2009-11-01

The ability to form long-term memories exists very early during ontogeny; however, the properties of early memory processes, brain structures involved and underlying cellular mechanisms are poorly defined. Here, we examine the role of extracellular signal-regulated kinase (ERK), a member of the mitogen-activated protein kinase/ERK signaling cascade, which is crucial for adult memory, in the consolidation and reconsolidation of an early memory using a conditioned taste aversion paradigm in 3-day-old rat pups. We show that intraperitoneal injection of SL327, the upstream mitogen-activated protein kinase kinase inhibitor, impairs both consolidation and reconsolidation of early memory, leaving short-term memory after acquisition and after reactivation intact. The amnesic effect of SL327 diminishes with increasing delays after acquisition and reactivation. Biochemical analyses revealed ERK hyperphosphorylation in the amygdala but not the hippocampus following acquisition, suggesting functional activation of the amygdala as early as post-natal day 3, although there was no clear evidence for amygdalar ERK activation after reactivation. These results indicate that, despite an immature brain, the basic properties of memory and at least some of the molecular mechanisms and brain structures implicated in aversion memory share a number of similarities with the adult and emerge very early during ontogeny.

Role of ERK/MAPK in endothelin receptor signaling in human aortic smooth muscle cells

DEFF Research Database (Denmark)

Chen, Qing-wen; Edvinsson, Lars; Xu, Cang-Bao

2009-01-01

muscle cells (VSMCs) through activation of endothelin type A (ETA) and type B (ETB) receptors. The extracellular signal-regulated kinase 1 and 2 (ERK1/2) mitogen-activated protein kinases (MAPK) are involved in ET-1-induced VSMC contraction and proliferation. This study was designed to investigate...... agonist, Sarafotoxin 6c (S6c) caused a time-dependent ERK1/2 activation with a maximal effect by less than 20% of the ET-1-induced activation of ERK1/2. Increase in bosentan concentration up to 10 microM further inhibited ET-1-induced activation of ERK1/2 and had a stronger inhibitory effect than BQ123...

Expression of phosphorylated extracellular signal-regulated kinase in rat kidneys exposed to high +Gz

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Hyun-Soo Kim

2012-11-01

Full Text Available Exposure to high gravitational acceleration forces acting along the body axis from the head to the feet (+Gz severely reduces blood flow to the visceral organs, including the kidneys. Extracellular signal-regulated kinase (ERK figures predominantly in mediating kidney cell responses to a wide variety of stress-related stimuli. Though previous studies have shown the activation of ERK in some experimental models, the regulation of ERK associated with +Gz exposure has not yet been investigated. The aim of this study was to examine the effect of high +Gz exposure on ERK activation in the kidneys. Using a small animal centrifuge, eight male Sprague-Dawley rats were exposed to +10Gz or +13Gz three times for 3 minutes each. The bilateral kidneys were obtained from each rat, and the expression levels of phosphorylated ERK (p-ERK were evaluated using immunohistochemistry. In the control group, the collecting duct epithelium displayed faint cytoplasmic staining with no nuclear staining of p-ERK. By contrast, rats exposed to +10Gz showed strong nuclear staining intensity for p-ERK. In the renal papilla, the epithelial cells of collecting ducts and thin segments of the loop of Henle exhibited strong nuclear immunoreactivity for p-ERK. Rats exposed to +13Gz also showed the same staining intensity and distribution of p-ERK expression as that of rats exposed to +10Gz. This study is the first to describe +Gz exposure-induced alteration in the expression of p-ERK in the kidneys. Our finding suggests that high +Gz exposure leads to the activation of ERK in the renal papilla.

Src Family Kinases and p38 Mitogen-Activated Protein Kinases Regulate Pluripotent Cell Differentiation in Culture.

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Boon Siang Nicholas Tan

Full Text Available Multiple pluripotent cell populations, which together comprise the pluripotent cell lineage, have been identified. The mechanisms that control the progression between these populations are still poorly understood. The formation of early primitive ectoderm-like (EPL cells from mouse embryonic stem (mES cells provides a model to understand how one such transition is regulated. EPL cells form from mES cells in response to l-proline uptake through the transporter Slc38a2. Using inhibitors of cell signaling we have shown that Src family kinases, p38 MAPK, ERK1/2 and GSK3β are required for the transition between mES and EPL cells. ERK1/2, c-Src and GSK3β are likely to be enforcing a receptive, primed state in mES cells, while Src family kinases and p38 MAPK are involved in the establishment of EPL cells. Inhibition of these pathways prevented the acquisition of most, but not all, features of EPL cells, suggesting that other pathways are required. L-proline activation of differentiation is mediated through metabolism and changes to intracellular metabolite levels, specifically reactive oxygen species. The implication of multiple signaling pathways in the process suggests a model in which the context of Src family kinase activation determines the outcomes of pluripotent cell differentiation.

Src Family Kinases and p38 Mitogen-Activated Protein Kinases Regulate Pluripotent Cell Differentiation in Culture

Science.gov (United States)

Tan, Boon Siang Nicholas; Kwek, Joly; Wong, Chong Kum Edwin; Saner, Nicholas J.; Yap, Charlotte; Felquer, Fernando; Morris, Michael B.; Gardner, David K.; Rathjen, Peter D.; Rathjen, Joy

2016-01-01

Multiple pluripotent cell populations, which together comprise the pluripotent cell lineage, have been identified. The mechanisms that control the progression between these populations are still poorly understood. The formation of early primitive ectoderm-like (EPL) cells from mouse embryonic stem (mES) cells provides a model to understand how one such transition is regulated. EPL cells form from mES cells in response to l-proline uptake through the transporter Slc38a2. Using inhibitors of cell signaling we have shown that Src family kinases, p38 MAPK, ERK1/2 and GSK3β are required for the transition between mES and EPL cells. ERK1/2, c-Src and GSK3β are likely to be enforcing a receptive, primed state in mES cells, while Src family kinases and p38 MAPK are involved in the establishment of EPL cells. Inhibition of these pathways prevented the acquisition of most, but not all, features of EPL cells, suggesting that other pathways are required. L-proline activation of differentiation is mediated through metabolism and changes to intracellular metabolite levels, specifically reactive oxygen species. The implication of multiple signaling pathways in the process suggests a model in which the context of Src family kinase activation determines the outcomes of pluripotent cell differentiation. PMID:27723793

Activation of ERK signalling by Src family kinases (SFKs) in DRG neurons contributes to hydrogen peroxide (H2O2)-induced thermal hyperalgesia.

Science.gov (United States)

Singh, Ajeet Kumar; Vinayak, Manjula

2017-10-01

Concomitant generation of reactive oxygen species during tissue inflammation has been recognised as a major factor for the development and the maintenance of hyperalgesia, out of which H 2 O 2 is the major player. However, molecular mechanism of H 2 O 2 induced hyperalgesia is still obscure. The aim of present study is to analyse the mechanism of H 2 O 2 -induced hyperalgesia in rats. Intraplantar injection of H 2 O 2 (5, 10 and 20 µmoles/paw) induced a significant thermal hyperalgesia in the hind paw, confirmed by increased c-Fos activity in dorsal horn of spinal cord. Onset of hyperalgesia was prior to development of oxidative stress and inflammation. Rapid increase in phosphorylation of extracellular signal regulated kinase (ERK) was observed in neurons of dorsal root ganglia after 20 min of H 2 O 2 (10 µmoles/paw) administration, which gradually returned towards normal level within 24 h, following the pattern of thermal hyperalgesia. The expression of TNFR1 followed the same pattern and colocalised with pERK. ERK phosphorylation was observed in NF-200-positive and -negative neurons, indicating the involvement of ERK in C-fibres as well as in A-fibres. Intrathecal preadministration of Src family kinases (SFKs) inhibitor (PP1) and MEK inhibitor (PD98059) prevented H 2 O 2 induced augmentation of ERK phosphorylation and thermal hyperalgesia. Pretreatment of protein tyrosine phosphatases (PTPs) inhibitor (sodium orthovanadate) also diminished hyperalgesia, although it further increased ERK phosphorylation. Combination of orthovanadate with PP1 or PD98059 did not exhibit synergistic antihyperalgesic effect. The results demonstrate SFKs-mediated ERK activation and increased TNFR1 expression in nociceptive neurons during H 2 O 2 induced hyperalgesia. However, the role of PTPs in hyperalgesic behaviour needs further molecular analysis.

Mitogen activated protein kinases selectively regulate palytoxin-stimulated gene expression in mouse keratinocytes

International Nuclear Information System (INIS)

Zeliadt, Nicholette A.; Warmka, Janel K.; Wattenberg, Elizabeth V.

2003-01-01

We have been investigating how the novel skin tumor promoter palytoxin transmits signals through mitogen activated protein kinases (MAPKs). Palytoxin activates three major MAPKs, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38, in a keratinocyte cell line derived from initiated mouse skin (308). We previously showed that palytoxin requires ERK to increase matrix metalloproteinase-13 (MMP-13) gene expression, an enzyme implicated in carcinogenesis. Diverse stimuli require JNK and p38 to increase MMP-13 gene expression, however. We therefore used the JNK and p38 inhibitors SP 600125 and SB 202190, respectively, to investigate the role of these MAPKs in palytoxin-induced MMP-13 gene expression. Surprisingly, palytoxin does not require JNK and p38 to increase MMP-13 gene expression. Accordingly, ERK activation, independent of palytoxin and in the absence of JNK and p38 activation, is sufficient to induce MMP-13 gene expression in 308 keratinocytes. Dexamethasone, a synthetic glucocorticoid that inhibits activator protein-1 (AP-1), blocked palytoxin-stimulated MMP-13 gene expression. Therefore, the AP-1 site present in the promoter of the MMP-13 gene appears to be functional and to play a key role in palytoxin-stimulated gene expression. Previous studies showed that palytoxin simulates an ERK-dependent selective increase in the c-Fos content of AP-1 complexes that bind to the promoter of the MMP-13 gene. JNK and p38 can also modulate c-Fos. Palytoxin does not require JNK or p38 to increase c-Fos binding, however. Altogether, these studies indicate that ERK plays a distinctly essential role in transmitting palytoxin-stimulated signals to specific nuclear targets in keratinocytes derived from initiated mouse skin

Nitric Oxide and ERK mediates regulation of cellular processes by Ecdysterone

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Omanakuttan, Athira; Bose, Chinchu; Pandurangan, Nanjan; Kumar, Geetha B.; Banerji, Asoke; Nair, Bipin G., E-mail: bipin@amrita.edu

2016-08-15

The complex process of wound healing is a major problem associated with diabetes, venous or arterial disease, old age and infection. A wide range of pharmacological effects including anabolic, anti-diabetic and hepato-protective activities have been attributed to Ecdysterone. In earlier studies, Ecdysterone has been shown to modulate eNOS and iNOS expression in diabetic animals and activate osteogenic differentiation through the Extracellular-signal-Regulated Kinase (ERK) pathway in periodontal ligament stem cells. However, in the wound healing process, Ecdysterone has only been shown to enhance granulation tissue formation in rabbits. There have been no studies to date, which elucidate the molecular mechanism underlying the complex cellular process involved in wound healing. The present study, demonstrates a novel interaction between the phytosteroid Ecdysterone and Nitric Oxide Synthase (NOS), in an Epidermal Growth Factor Receptor (EGFR)-dependent manner, thereby promoting cell proliferation, cell spreading and cell migration. These observations were further supported by the 4-amino-5-methylamino- 2′ ,7′ -difluorofluorescein diacetate (DAF FM) fluorescence assay which indicated that Ecdysterone activates NOS resulting in increased Nitric Oxide (NO) production. Additionally, studies with inhibitors of both the EGFR and ERK, demonstrated that Ecdysterone activates NOS through modulation of EGFR and ERK. These results clearly demonstrate, for the first time, that Ecdysterone enhances Nitric Oxide production and modulates complex cellular processes by activating ERK1/2 through the EGF pathway. - Highlights: • Ecdysterone significantly enhances cell migration in a dose dependent manner. • Ecdysterone augments cell spreading during the initial phase of cell migration through actin cytoskeletal rearrangement. • Ecdysterone enhances cell proliferation in a nitric oxide dependent manner. • Ecdysterone enhances nitric oxide production via activation of EGFR

Nitric Oxide and ERK mediates regulation of cellular processes by Ecdysterone

International Nuclear Information System (INIS)

Omanakuttan, Athira; Bose, Chinchu; Pandurangan, Nanjan; Kumar, Geetha B.; Banerji, Asoke; Nair, Bipin G.

2016-01-01

The complex process of wound healing is a major problem associated with diabetes, venous or arterial disease, old age and infection. A wide range of pharmacological effects including anabolic, anti-diabetic and hepato-protective activities have been attributed to Ecdysterone. In earlier studies, Ecdysterone has been shown to modulate eNOS and iNOS expression in diabetic animals and activate osteogenic differentiation through the Extracellular-signal-Regulated Kinase (ERK) pathway in periodontal ligament stem cells. However, in the wound healing process, Ecdysterone has only been shown to enhance granulation tissue formation in rabbits. There have been no studies to date, which elucidate the molecular mechanism underlying the complex cellular process involved in wound healing. The present study, demonstrates a novel interaction between the phytosteroid Ecdysterone and Nitric Oxide Synthase (NOS), in an Epidermal Growth Factor Receptor (EGFR)-dependent manner, thereby promoting cell proliferation, cell spreading and cell migration. These observations were further supported by the 4-amino-5-methylamino- 2′ ,7′ -difluorofluorescein diacetate (DAF FM) fluorescence assay which indicated that Ecdysterone activates NOS resulting in increased Nitric Oxide (NO) production. Additionally, studies with inhibitors of both the EGFR and ERK, demonstrated that Ecdysterone activates NOS through modulation of EGFR and ERK. These results clearly demonstrate, for the first time, that Ecdysterone enhances Nitric Oxide production and modulates complex cellular processes by activating ERK1/2 through the EGF pathway. - Highlights: • Ecdysterone significantly enhances cell migration in a dose dependent manner. • Ecdysterone augments cell spreading during the initial phase of cell migration through actin cytoskeletal rearrangement. • Ecdysterone enhances cell proliferation in a nitric oxide dependent manner. • Ecdysterone enhances nitric oxide production via activation of EGFR

Conditional deletion of ERK5 MAP kinase in the nervous system impairs pheromone information processing and pheromone-evoked behaviors.

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Junhui Zou

Full Text Available ERK5 MAP kinase is highly expressed in the developing nervous system but absent in most regions of the adult brain. It has been implicated in regulating the development of the main olfactory bulb and in odor discrimination. However, whether it plays an essential role in pheromone-based behavior has not been established. Here we report that conditional deletion of the Mapk7 gene which encodes ERK5 in mice in neural stem cells impairs several pheromone-mediated behaviors including aggression and mating in male mice. These deficits were not caused by a reduction in the level of testosterone, by physical immobility, by heightened fear or anxiety, or by depression. Using mouse urine as a natural pheromone-containing solution, we provide evidence that the behavior impairment was associated with defects in the detection of closely related pheromones as well as with changes in their innate preference for pheromones related to sexual and reproductive activities. We conclude that expression of ERK5 during development is critical for pheromone response and associated animal behavior in adult mice.

Fisetin Enhances the Cytotoxicity of Gemcitabine by Down-regulating ERK-MYC in MiaPaca-2 Human Pancreatic Cancer Cells.

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Kim, Nayoung; Kang, Min-Jung; Lee, Sang Hyub; Son, Jun Hyuk; Lee, Ji Eun; Paik, Woo Hyun; Ryu, Ji Kon; Kim, Yong-Tae

2018-06-01

Pancreatic cancer is a highly lethal malignancy with a poor prognosis. This study was set up to investigate the combined effect of gemcitabine and fisetin, a natural flavonoid from plants, on human pancreatic cancer cells. Meterials and Methods: Cytotoxic effect of fisetin in combination with gemcitabine on MiaPaca-2 cells was evaluated by the MTT assay, caspase 3/7 assay and propidium iodide/Annexin V. Extracellular signal-regulated kinase (ERK)-v-myc avian myelocytomatosis viral oncogene homolog (MYC) pathway was investigated by western blotting and quantitative real-time polymerase chain reaction. Combination treatment with fisetin and gemcitabine inhibited the proliferation of pancreatic cancer cells within 72 h and induced apoptosis, as indicated by activation of caspase 3/7. Fisetin down-regulated ERK at the protein and mRNA levels, and reduced ERK-induced MYC instability at the protein level. Fisetin sensitized human pancreatic cancer cells to gemcitabine-induced cytotoxicity through inhibition of ERK-MYC signaling. These results suggest that the combination of fisetin and gemcitabine could be developed as a novel potent therapeutic. Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Evidence for Elevated Cerebrospinal Fluid ERK1/2 Levels in Alzheimer Dementia

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Philipp Spitzer

2011-01-01

Full Text Available Cerebrospinal fluid (CSF samples from 33 patients with Alzheimer dementia (AD, 21 patients with mild cognitive impairment who converted to AD during followup (MCI-AD, 25 patients with stable mild cognitive impairment (MCI-stable, and 16 nondemented subjects (ND were analyzed with a chemiluminescence immunoassay to assess the levels of the mitogen-activated protein kinase ERK1/2 (extracellular signal-regulated kinase 1/2. The results were evaluated in relation to total Tau (tTau, phosphorylated Tau (pTau, and beta-amyloid 42 peptide (Aβ42. CSF-ERK1/2 was significantly increased in the AD group as compared to stable MCI patients and the ND group. Western blot analysis of a pooled cerebrospinal fluid sample revealed that both isoforms, ERK1 and ERK2, and low amounts of doubly phosphorylated ERK2 were detectable. As a predictive diagnostic AD biomarker, CSF-ERK1/2 was inferior to tTau, pTau, and Aβ42.

The CYP2E1 inhibitor DDC up-regulates MMP-1 expression in hepatic stellate cells via an ERK1/2- and Akt-dependent mechanism.

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Liu, Tianhui; Wang, Ping; Cong, Min; Xu, Youqing; Jia, Jidong; You, Hong

2013-06-05

DDC (diethyldithiocarbamate) could block collagen synthesis in HSC (hepatic stellate cells) through the inhibition of ROS (reactive oxygen species) derived from hepatocyte CYP2E1 (cytochrome P450 2E1). However, the effect of DDC on MMP-1 (matrix metalloproteinase-1), which is the main collagen degrading matrix metalloproteinase, has not been reported. In co-culture experiments, we found that DDC significantly enhanced MMP-1 expression in human HSC (LX-2) that were cultured with hepatocyte C3A cells either expressing or not expressing CYP2E1. The levels of both proenzyme and active MMP-1 enzyme were up-regulated in LX-2 cells, accompanied by elevated enzyme activity of MMP-1 and decreased collagen I, in both LX-2 cells and the culture medium. H2O2 treatment abrogated DDC-induced MMP-1 up-regulation and collagen I decrease, while catalase treatment slightly up-regulated MMP-1 expression. These data suggested that the decrease in ROS by DDC was partially responsible for the MMP-1 up-regulation. ERK1/2 (extracellular signal-regulated kinase 1/2), Akt (protein kinase B) and p38 were significantly activated by DDC. The ERK1/2 inhibitor (U0126) and Akt inhibitor (T3830) abrogated the DDC-induced MMP-1 up-regulation. In addition, a p38 inhibitor (SB203580) improved MMP-1 up-regulation through the stimulation of ERK1/2. Our data indicate that DDC significantly up-regulates the expression of MMP-1 in LX-2 cells which results in greater MMP-1 enzyme activity and decreased collagen I. The enhancement of MMP-1 expression by DDC was associated with H2O2 inhibition and coordinated regulation by the ERK1/2 and Akt pathways. These data provide some new insights into treatment strategies for hepatic fibrosis.

Appetitive Cue-Evoked ERK Signaling in the Nucleus Accumbens Requires NMDA and D1 Dopamine Receptor Activation and Regulates CREB Phosphorylation

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Kirschmann, Erin K. Z.; Mauna, Jocelyn C.; Willis, Cory M.; Foster, Rebecca L.; Chipman, Amanda M.; Thiels, Edda

2014-01-01

Conditioned stimuli (CS) can modulate reward-seeking behavior. This modulatory effect can be maladaptive and has been implicated in excessive reward seeking and relapse to drug addiction. We previously demonstrated that exposure to an appetitive CS causes an increase in the activation of extracellular signal-regulated kinase (ERK) and cyclic-AMP…

Amitriptyline induces early growth response-1 gene expression via ERK and JNK mitogen-activated protein kinase pathways in rat C6 glial cells.

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Chung, Eun Young; Shin, Soon Young; Lee, Young Han

2007-07-05

Astrocytes play important roles in guiding the construction of the nervous system, controlling extracellular ions and neurotransmitters, and regulating CNS synaptogenesis. Egr-1 is a transcription factor involved in neuronal differentiation and astrocyte cell proliferation. In this study, we investigated whether the tricyclic antidepressant (TCA) amitriptyline induces Egr-1 expression in astrocytes using rat C6 glioma cells as a model. We found that amitriptyline increased the expression of Egr-1 in a dose- and time-dependent manner. The amitriptyline-induced Egr-1 expression was mediated through serum response elements (SREs) in the Egr-1 promoter. SREs were activated by the Ets-domain transcription factor Elk-1 through the ERK and JNK mitogen-activated protein (MAP) kinase pathways. The inhibition of the ERK and JNK MAP kinase signals attenuated amitriptyline-induced transactivation of Gal4-Elk-1 and Egr-1 promoter activity. Our findings suggest that the induction of Egr-1 expression in astrocytes may be required to attain the therapeutic effects of antidepressant drugs.

Oryza sativa (Rice) Hull Extract Inhibits Lipopolysaccharide-Induced Inflammatory Response in RAW264.7 Macrophages by Suppressing Extracellular Signal-regulated Kinase, c-Jun N-terminal Kinase, and Nuclear Factor-κB Activation.

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Ha, Sang Keun; Sung, Jeehye; Choi, Inwook; Kim, Yoonsook

2016-01-01

Rice ( Oryza sativa ) is a major cereal crop in many Asian countries and an important staple food source. Rice hulls have been reported to possess antioxidant activities. In this study, we evaluated the antiinflammatory effects of rice hull extract and associated signal transduction mechanisms in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. We found that rice hull extract inhibited nitric oxide (NO) and prostaglandin E 2 by suppressing the expression of inducible NO synthase and cyclooxygenase-2, respectively. The release of interleukin-1β and tumor necrosis factor-α was also reduced in a dose-dependent manner. Furthermore, rice hull extract attenuated the activation of nuclear factor-kappa B (NF-κB), as well as the phosphorylation of mitogen-activated protein kinases, extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK), in LPS-stimulated RAW264.7 cells. This suggests that rice hull extract decreases the production of inflammatory mediators by downregulating ERK and JNK and the NF-κB signal pathway in RAW 264.7 cells. Rice hull extract inhibits the lipopolysaccharide-induced inflammatory response in RAW264.7 macrophages.Rice hull extract inhibited nitric oxide and prostaglandin E 2 by suppressing the expression of inducible NO synthase and cyclooxygenase-2, respectively.Rice hull extract exerted anti-inflammatory effect through inhibition of nuclear factor-kappa B, extracellular signal-regulated kinase and c-Jun N-terminal kinase signaling pathways.Rice hull extract may provide a potential therapeutic approach for inflammatory diseases. Abbreviations used: COX-2: cyclooxygenase-2, ERK: extracellular signal-regulated kinase, IκB: inhibitory kappa B, IL-1β: interleukin-1β, iNOS: inducible NO synthase, JNK: c-Jun N-terminal kinase, LPS: lipopolysaccharide, MAPKs: mitogen-activated protein kinases, NF-κB: nuclear factor-κB, NO: nitric oxide, PGE2: prostaglandin E2, RHE: rice hull extract, ROS: reactive oxygen species

Exercise training protects against atherosclerotic risk factors through vascular NADPH oxidase, extracellular signal-regulated kinase 1/2 and stress-activated protein kinase/c-Jun N-terminal kinase downregulation in obese rats.

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Touati, Sabeur; Montezano, Augusto C I; Meziri, Fayçal; Riva, Catherine; Touyz, Rhian M; Laurant, Pascal

2015-02-01

Exercise training reverses atherosclerotic risk factors associated with metabolic syndrome and obesity. The aim of the present study was to determine the molecular anti-inflammatory, anti-oxidative and anti-atherogenic effects in aorta from rats with high-fat diet-induced obesity. Male Sprague-Dawley rats were placed on a high-fat (HFD) or control (CD) diet for 12 weeks. The HFD rats were then divided into four groups: (i) sedentary HFD-fed rats (HFD-S); (ii) exercise trained (motor treadmill 5 days/week, 60 min/day, 12 weeks) HFD-fed rats (HFD-Ex); (iii) modified diet (HFD to CD) sedentary rats (HF/CD-S); and (iv) an exercise-trained modified diet group (HF/CD-Ex). Tissue levels of NADPH oxidase (activity and expression), NADPH oxidase (Nox) 1, Nox2, Nox4, p47(phox) , superoxide dismutase (SOD)-1, angiotensin AT1 and AT2 receptors, phosphorylated mitogen-activated protein kinase (MAPK; extracellular signal-regulated kinase (ERK) 1/2, stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK)) and vascular cell adhesion molecule-1 (VCAM-1) were determined in the aorta. Plasma cytokines (tumour necrosis factor (TNF)-α and interleukin (IL)-6) levels were also measured. Obesity was accompanied by increases in NADPH oxidase activity, p47(phox) translocation, Nox4 and VCAM-1 protein expression, MAPK (ERK1/2, SAPK/JNK) phosphorylation and plasma TNF-α and IL-6 levels. Exercise training and switching from the HFD to CD reversed almost all these molecular changes. In addition, training increased aortic SOD-1 protein expression and decreased ERK1/2 phosphorylation. These findings suggest that protective effects of exercise training on atherosclerotic risk factors induced by obesity are associated with downregulation of NADPH oxidase, ERK1/2 and SAPK/JNK activity and increased SOD-1 expression. © 2014 Wiley Publishing Asia Pty Ltd.

Blockade of the ERK pathway markedly sensitizes tumor cells to HDAC inhibitor-induced cell death

International Nuclear Information System (INIS)

Ozaki, Kei-ichi; Minoda, Ai; Kishikawa, Futaba; Kohno, Michiaki

2006-01-01

Constitutive activation of the extracellular signal-regulated kinase (ERK) pathway is associated with the neoplastic phenotype of a large number of human tumor cells. Although specific blockade of the ERK pathway by treating such tumor cells with potent mitogen-activated protein kinase/ERK kinase (MEK) inhibitors completely suppresses their proliferation, it by itself shows only a modest effect on the induction of apoptotic cell death. However, these MEK inhibitors markedly enhance the efficacy of histone deacetylase (HDAC) inhibitors to induce apoptotic cell death: such an enhanced cell death is observed only in tumor cells in which the ERK pathway is constitutively activated. Co-administration of MEK inhibitor markedly sensitizes tumor cells to HDAC inhibitor-induced generation of reactive oxygen species, which appears to mediate the enhanced cell death induced by the combination of these agents. These results suggest that the combination of MEK inhibitors and HDAC inhibitors provides an efficient chemotherapeutic strategy for the treatment of tumor cells in which the ERK pathway is constitutively activated

ERK5 and cell proliferation: nuclear localization is what matters

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Nestor Gomez

2016-09-01

Full Text Available ERK5, the last MAP kinase family member discovered, is activated by the upstream kinase MEK5 in response to growth factors and stress stimulation. MEK5-ERK5 pathway has been associated to different cellular processes, playing a crucial role in cell proliferation in normal and cancer cells by mechanisms that are both dependent and independent of its kinase activity. Thus, nuclear ERK5 activates transcription factors by either direct phosphorylation or acting as co-activator thanks to a unique transcriptional activation TAD domain located at its C-terminal tail. Consequently, ERK5 has been proposed as an interesting target to tackle different cancers, and either inhibitors of ERK5 activity or silencing the protein have shown antiproliferative activity in cancer cells and to block tumour growth in animal models. Here, we review the different mechanisms involved in ERK5 nuclear translocation and their consequences. Inactive ERK5 resides in the cytosol, forming a complex with Hsp90-Cdc37 superchaperone. In a canonical mechanism, MEK5-dependent activation results in ERK5 C-terminal autophosphorylation, Hsp90 dissociation and nuclear translocation. This mechanism integrates signals such as growth factors and stresses that activate the MEK5-ERK5 pathway. Importantly, two other mechanisms, MEK5-independent, have been recently described. These mechanisms allow nuclear shuttling of kinase-inactive forms of ERK5. Although lacking kinase activity, these forms activate transcription by interacting with transcription factors through the TAD domain. Both mechanisms also require Hsp90 dissociation previous to nuclear translocation. One mechanism involves phosphorylation of the C-terminal tail of ERK5 by kinases that are activated during mitosis, such as Cyclin-dependent kinase-1. The second mechanism involves overexpression of chaperone Cdc37, an oncogene that is overexpressed in cancers such as prostate adenocarcinoma, where it collaborates with ERK5 to promote

Learned stressor resistance requires extracellular signal-regulated kinase in the prefrontal cortex

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John Paul Christianson

2014-10-01

Full Text Available Behaviorally controllable stressors confer protection from the neurochemical and behavioral consequences of future uncontrollable stressors, a phenomenon termed behavioral immunization. Recent data implicate neuroplasticity within the ventromedial prefrontal cortex (mPFC as critical to behavioral immunization. Adult, male Sprague-Dawley rats were exposed to a series of controllable tailshocks and one week later to uncontrollable tailshocks, followed 24h later by social exploration and shuttlebox escape tests. To test the involvement of N-methyl-D-aspartate receptors (NMDAR and the extracellular signal-regulated kinase (ERK cascade in behavioral immunization, either D-AP5 or the MEK inhibitor U0126 was injected to the prelimbic (PL or infralimbic (IL mPFC prior to controllable stress exposure. Phosphorylated ERK and P70S6K, regulators of transcription and translation, were quantified by Western blot or immunohistochemistry after controllable or uncontrollable tailshocks. Prior controllable stress prevented the social exploration and shuttlebox performance deficits caused by the later uncontrollable stressor, and this effect was blocked by injections of D-AP5 into mPFC. A significant increase in phosphorylated ERK1 and ERK2, but not P70S6K, occurred within the PL and IL in rats exposed to controllable stress, but not to uncontrollable stress. However, U0126 only prevented behavioral immunization when injected to the PL. We provide evidence that NMDAR and ERK dependent plasticity within the PL region is required for behavioral immunization, a learned form of stressor resistance.

ERK2 dependent signaling contributes to wound healing after a partial-thickness burn

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Satoh, Yasushi; Saitoh, Daizoh; Takeuchi, Atsuya; Ojima, Kenichiro; Kouzu, Keita; Kawakami, Saki; Ito, Masataka; Ishihara, Masayuki; Sato, Shunichi; Takishima, Kunio

2009-01-01

Burn healing is a complex physiological process involving multiple cell activities, such as cell proliferation, migration and differentiation. Although extracellular signal-regulated kinases (ERK) have a pivotal role in regulating a variety of cellular responses, little is known about the individual functions of ERK isoform for healing in vivo. This study investigated the role of ERK2 in burn healing. To assess this, Erk2 +/- mice generated by gene targeting were used. The resultant mice exhibited significant delay in re-epithelization of partial-thickness burns in the skin in comparison to wild-type. An in vitro proliferation assay revealed that keratinocytes from Erk2 +/- mice grew significantly slower than those prepared from wild-type. These results highlight the importance of ERK2 in the process of burn healing.

Growth arrest- and DNA-damage-inducible 45beta gene inhibits c-Jun N-terminal kinase and extracellular signal-regulated kinase and decreases IL-1beta-induced apoptosis in insulin-producing INS-1E cells

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Larsen, Claus Morten; Døssing, M G; Papa, S

2006-01-01

IL-1beta is a candidate mediator of apoptotic beta cell destruction, a process that leads to type 1 diabetes and progression of type 2 diabetes. IL-1beta activates beta cell c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and p38, all of which are members of the mitogen...

MEK/ERK and p38 MAPK regulate chondrogenesis of rat bone marrow mesenchymal stem cells through delicate interaction with TGF-beta1/Smads pathway.

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Li, J; Zhao, Z; Liu, J; Huang, N; Long, D; Wang, J; Li, X; Liu, Y

2010-08-01

This study was carried out to reveal functions and mechanisms of MEK/ERK and p38 pathways in chondrogenesis of rat bone marrow mesenchymal stem cells (BMSCs), and to investigate further any interactions between the mitogen-activated protein kinase (MAPK) and transforming growth factor-beta1 (TGF-beta1)/Smads pathway in the process. Chondrogenic differentiation of rat BMSCs was initiated in micromass culture, in the presence of TGF-beta1, for 2 weeks. ERK1/2 and p38 kinase activities were investigated by Western Blot analysis. Specific MAPK inhibitors PD98059 and SB20350 were employed to investigate regulatory effects of MEK/ERK and p38 signals on gene expression of chondrocyte-specific markers, and TGF-beta1 downstream pathways of Smad2/3. ERK1/2 was phosphorylated in a rapid but transient manner, whereas p38 was activated in a slow and sustained way. The two MAPK subtypes played opposing roles in mediating transcription of cartilage-specific genes for Col2alpha and aggrecan. TGF-beta1-stimulated gene expression of chondrogenic regulators, Sox9, Runx2 and Ihh, was also affected by activity of PD98059 and SB203580, to different degrees. However, influences of MAPK inhibitors on gene expression were relatively minor when not treated with TGF-beta1. In addition, gene transcription of Smad2/3 was significantly upregulated by TGF-beta1, but was regulated more subtly by treatment with MAPK inhibitors. MAPK subtypes seemed to regulate chondrogenesis with a delicate balance, interacting with the TGF-beta1/Smads signalling pathway.

p16(INK4A) inhibits the pro-metastatic potentials of osteosarcoma cells through targeting the ERK pathway and TGF-β1.

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Silva, Gabriela; Aboussekhra, Abdelilah

2016-05-01

Extracellular signal-regulated kinase (ERK) is a downstream component of the evolutionarily conserved mitogen-activated protein kinase-signaling pathway, which controls the expression of a plethora of genes implicated in various physiological processes. This pathway is often hyper-activated by mutations or abnormal extracellular signaling in different types of human cancer, including the most common primary malignant bone tumor osteosarcomas. p16(INK4A) is an important tumor suppressor gene frequently lost in osteosarcomas, and is associated with the progression of these malignancies. We have shown, here, that the ERK1/2 protein kinase is also activated by p16(INK4A) down-regulation in osteosarcoma cells and normal human as well as mouse cells. This inhibitory effect is associated with the suppression of the upstream kinase MEK1/2, and is mediated via the repression of miR-21-5p and the consequent up-regulation of the MEK/ERK antagonist SPRY2 in osteosarcoma cells. Furthermore, we have shown that p16(INK4) inhibits the migration/invasion abilities of these cells through miR-21-5p-dependent inhibition of ERK1/2. In addition, we present clear evidence that p16(INK4) represses the paracrine pro-migratory effect of osteosarcoma cells on stromal fibroblasts through the inhibition of the TGF-β1 expression/secretion. This effect is also ERK1/2-dependent, indicating that in addition to their cell-autonomous actions, p16(INK4) and ERK1/2 have also non-cell-autonomous cancer-related functions. Together, these results indicate that the tumor suppressor p16(INK4) protein represses the carcinogenic process of osteosarcoma cells not only as a cell cycle regulator, but also as a negative regulator of pro-carcinogenic/-metastatic pathways. This indicates that targeting the ERK pathway is of utmost therapeutic value. © 2015 Wiley Periodicals, Inc.

Inhibition of Extracellular Signal-Regulated Kinases Ameliorates Hypertension-Induced Renal Vascular Remodeling in Rat Models

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Li Jing

2011-11-01

Full Text Available The aim of this study is to investigate the effect of the extracellular signal-regulated kinases 1/2 (ERK1/2 inhibitor, PD98059, on high blood pressure and related vascular changes. Blood pressure was recorded, thicknesses of renal small artery walls were measured and ERK1/2 immunoreactivity and erk2 mRNA in renal vascular smooth muscle cells (VSMCs and endothelial cells were detected by immunohistochemistry and in situ hybridization in normotensive wistar kyoto (WKY rats, spontaneously hypertensive rats (SHR and PD98059-treated SHR. Compared with normo-tensive WKY rats, SHR developed hypertension at 8 weeks of age, thickened renal small artery wall and asymmetric arrangement of VSMCs at 16 and 24 weeks of age. Phospho-ERK1/2 immunoreactivity and erk2 mRNA expression levels were increased in VSMCs and endothelial cells of the renal small arteries in the SHR. Treating SHR with PD98059 reduced the spontaneous hypertension-induced vascular wall thickening. This effect was associated with suppressions of erk2 mRNA expression and ERK1/2 phosphorylation in VSMCs and endothelial cells of the renal small arteries. It is concluded that inhibition of ERK1/2 ameliorates hypertension induced vascular remodeling in renal small arteries.

Neural cell adhesion molecule-stimulated neurite outgrowth depends on activation of protein kinase C and the Ras-mitogen-activated protein kinase pathway

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Kolkova, K; Novitskaya, V; Pedersen, N

2000-01-01

, inhibitors of the nonreceptor tyrosine kinase p59(fyn), PLC, PKC and MEK and an activator of PKC, phorbol-12-myristate-13-acetate (PMA). MEK2 transfection rescued cells treated with all inhibitors. The same was found for PMA treatment, except when cells concomitantly were treated with the MEK inhibitor....... Arachidonic acid rescued cells treated with antibodies to the FGF receptor or the PLC inhibitor, but not cells in which the activity of PKC, p59(fyn), FAK, Ras, or MEK was inhibited. Interaction of NCAM with a synthetic NCAM peptide ligand, known to induce neurite outgrowth, was shown to stimulate...... phosphorylation of the MAP kinases extracellular signal-regulated kinases ERK1 and ERK2. The MAP kinase activation was sustained, because ERK1 and ERK2 were phosphorylated in PC12-E2 cells and primary hippocampal neurons even after 24 hr of cultivation on NCAM-expressing fibroblasts. Based on these results, we...

Albumin-induced apoptosis of glomerular parietal epithelial cells is modulated by extracellular signal-regulated kinase 1/2

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Ohse, Takamoto; Krofft, Ron D.; Wu, Jimmy S.; Eddy, Allison A.; Pippin, Jeffrey W.; Shankland, Stuart J.

2012-01-01

Background. The biological role(s) of glomerular parietal epithelial cells (PECs) is not fully understood in health or disease. Given its location, PECs are constantly exposed to low levels of filtered albumin, which is increased in nephrotic states. We tested the hypothesis that PECs internalize albumin and increased uptake results in apoptosis. Methods. Confocal microscopy of immunofluorescent staining and immunohistochemistry were used to demonstrate albumin internalization in PECs and to quantitate albumin uptake in normal mice and rats as well as experimental models of membranous nephropathy, minimal change disease/focal segmental glomerulosclerosis and protein overload nephropathy. Fluorescence-activated cell sorting analysis was performed on immortalized cultured PECs exposed to fluorescein isothiocyanate (FITC)-labeled albumin in the presence of an endosomal inhibitor or vehicle. Apoptosis was measured by Hoechst staining in cultured PECs exposed to bovine serum albumin. Levels of phosphorylated extracellular signal-regulated kinase 1 and 2 (p-ERK1/2) were restored by retroviral infection of mitogen-activated protein kinase (MEK) 1/2 and reduced by U0126 in PECs exposed to high albumin levels in culture and apoptosis measured by Hoechst staining. Results. PECs internalized albumin normally, and this was markedly increased in all of the experimental disease models (P PECs also internalize FITC-labeled albumin, which was reduced by endosomal inhibition. A consequence of increased albumin internalization was PEC apoptosis in vitro and in vivo. Candidate signaling pathways underlying these events were examined. Data showed markedly reduced levels of phosphorylated extracellular signal-regulated kinase 1 and 2 (ERK1/2) in PECs exposed to high albumin levels in nephropathy and in culture. A role for ERK1/2 in limiting albumin-induced apoptosis was shown by restoring p-ERK1/2 by retroviral infection, which reduced apoptosis in cultured PECs, while a forced

Role of ERK/MAPK in endothelin receptor signaling in human aortic smooth muscle cells

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Chen, Qing-wen; Edvinsson, Lars; Xu, Cang-Bao

2009-01-01

muscle cells (VSMCs) through activation of endothelin type A (ETA) and type B (ETB) receptors. The extracellular signal-regulated kinase 1 and 2 (ERK1/2) mitogen-activated protein kinases (MAPK) are involved in ET-1-induced VSMC contraction and proliferation. This study was designed to investigat...

Role of a cysteine residue in the active site of ERK and the MAPKK family

International Nuclear Information System (INIS)

Ohori, Makoto; Kinoshita, Takayoshi; Yoshimura, Seiji; Warizaya, Masaichi; Nakajima, Hidenori; Miyake, Hiroshi

2007-01-01

Kinases of mitogen-activated protein kinase (MAPK) cascades, including extracellular signal-regulated protein kinase (ERK), represent likely targets for pharmacological intervention in proliferative diseases. Here, we report that FR148083 inhibits ERK2 enzyme activity and TGFβ-induced AP-1-dependent luciferase expression with respective IC 50 values of 0.08 and 0.05 μM. FR265083 (1'-2' dihydro form) and FR263574 (1'-2' and 7'-8' tetrahydro form) exhibited 5.5-fold less and no activity, respectively, indicating that both the α,β-unsaturated ketone and the conformation of the lactone ring contribute to this inhibitory activity. The X-ray crystal structure of the ERK2/FR148083 complex revealed that the compound binds to the ATP binding site of ERK2, involving a covalent bond to Sγ of ERK2 Cys166, hydrogen bonds with the backbone NH of Met108, Nζ of Lys114, backbone C=O of Ser153, Nδ2 of Asn154, and hydrophobic interactions with the side chains of Ile31, Val39, Ala52, and Leu156. The covalent bond motif in the ERK2/FR148083 complex assures that the inhibitor has high activity for ERK2 and no activity for other MAPKs such as JNK1 and p38MAPKα/β/γ/δ which have leucine residues at the site corresponding to Cys166 in ERK2. On the other hand, MEK1 and MKK7, kinases of the MAPKK family which also can be inhibited by FR148083, contain a cysteine residue corresponding to Cys166 of ERK2. The covalent binding to the common cysteine residue in the ATP-binding site is therefore likely to play a crucial role in the inhibitory activity for these MAP kinases. These findings on the molecular recognition mechanisms of FR148083 for kinases with Cys166 should provide a novel strategy for the pharmacological intervention of MAPK cascades

Non-transactivational, dual pathways for LPA-induced Erk1/2 activation in primary cultures of brown pre-adipocytes

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Holmstroem, Therese E.; Mattsson, Charlotte L.; Wang, Yanling; Iakovleva, Irina; Petrovic, Natasa; Nedergaard, Jan

2010-01-01

In many cell types, G-protein-coupled receptor (GPCR)-induced Erk1/2 MAP kinase activation is mediated via receptor tyrosine kinase (RTK) transactivation, in particular via the epidermal growth factor (EGF) receptor. Lysophosphatidic acid (LPA), acting via GPCRs, is a mitogen and MAP kinase activator in many systems, and LPA can regulate adipocyte proliferation. The mechanism by which LPA activates the Erk1/2 MAP kinase is generally accepted to be via EGF receptor transactivation. In primary cultures of brown pre-adipocytes, EGF can induce Erk1/2 activation, which is obligatory and determinant for EGF-induced proliferation of these cells. Therefore, we have here examined whether LPA, via EGF transactivation, can activate Erk1/2 in brown pre-adipocytes. We found that LPA could induce Erk1/2 activation. However, the LPA-induced Erk1/2 activation was independent of transactivation of EGF receptors (or PDGF receptors) in these cells (whereas in transformed HIB-1B brown adipocytes, the LPA-induced Erk1/2 activation indeed proceeded via EGF receptor transactivation). In the brown pre-adipocytes, LPA instead induced Erk1/2 activation via two distinct non-transactivational pathways, one G i -protein dependent, involving PKC and Src activation, the other, a PTX-insensitive pathway, involving PI3K (but not Akt) activation. Earlier studies showing LPA-induced Erk1/2 activation being fully dependent on RTK transactivation have all been performed in cell lines and transfected cells. The present study implies that in non-transformed systems, RTK transactivation may not be involved in the mediation of GPCR-induced Erk1/2 MAP kinase activation.

RAS/ERK modulates TGFbeta-regulated PTEN expression in human pancreatic adenocarcinoma cells.

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Chow, Jimmy Y C; Quach, Khai T; Cabrera, Betty L; Cabral, Jennifer A; Beck, Stayce E; Carethers, John M

2007-11-01

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is rarely mutated in pancreatic cancers, but its regulation by transforming growth factor (TGF)-beta might mediate growth suppression and other oncogenic actions. Here, we examined the role of TGFbeta and the effects of oncogenic K-RAS/ERK upon PTEN expression in the absence of SMAD4. We utilized two SMAD4-null pancreatic cell lines, CAPAN-1 (K-RAS mutant) and BxPc-3 (WT-K-RAS), both of which express TGFbeta surface receptors. Cells were treated with TGFbeta1 and separated into cytosolic/nuclear fractions for western blotting with phospho-SMAD2, SMAD 2, 4 phospho-ATP-dependent tyrosine kinases (Akt), Akt and PTEN antibodies. PTEN mRNA levels were assessed by reverse transcriptase-polymerase chain reaction. The MEK1 inhibitor, PD98059, was used to block the downstream action of oncogenic K-RAS/ERK, as was a dominant-negative (DN) K-RAS construct. TGFbeta increased phospho-SMAD2 in both cytosolic and nuclear fractions. PD98059 treatment further increased phospho-SMAD2 in the nucleus of both pancreatic cell lines, and DN-K-RAS further improved SMAD translocation in K-RAS mutant CAPAN cells. TGFbeta treatment significantly suppressed PTEN protein levels concomitant with activation of Akt by 48 h through transcriptional reduction of PTEN mRNA that was evident by 6 h. TGFbeta-induced PTEN suppression was reversed by PD98059 and DN-K-RAS compared with treatments without TGFbeta. TGFbeta-induced PTEN expression was inversely related to cellular proliferation. Thus, oncogenic K-RAS/ERK in pancreatic adenocarcinoma facilitates TGFbeta-induced transcriptional down-regulation of the tumor suppressor PTEN in a SMAD4-independent manner and could constitute a signaling switch mechanism from growth suppression to growth promotion in pancreatic cancers.

Negative Regulation of Receptor Tyrosine Kinase (RTK Signaling: A Developing Field

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Fernanda Ledda

2007-01-01

Full Text Available ophic factors control cellular physiology by activating specific receptor tyrosine kinases (RTKs. While the over activation of RTK signaling pathways is associated with cell growth and cancer, recent findings support the concept that impaired down-regulation or deactivation of RTKs may also be a mechanism involved in tumor formation. Under this perspective, the molecular determinants of RTK signaling inhibition may act as tumor-suppressor genes and have a potential role as tumor markers to monitor and predict disease progression. Here, we review the current understanding of the physiological mechanisms that attenuate RTK signaling and discuss evidence that implicates deregulation of these events in cancer.Abbreviations: BDP1: Brain-derived phosphatase 1; Cbl: Casitas B-lineage lymphoma; CIN-85: Cbl-interacting protein of 85 kDa; DER: Drosophila EGFR; EGFR: Epidermal growth factor receptor; ERK 1/2: Extracellular signal-regulated kinase 1/2; Grb2: Growth factor receptor-bound protein 2; HER2: Human epidermal growth factor receptor 2; LRIG: Leucine-rich repeats and immunoglobulin-like domain 1; MAPK: Mitogen-activated protein kinase; Mig 6: Mitogen-inducible gene 6; PTEN: Phosphatase and tensin homologue; RET: Rearranged in transformation; RTK: Receptor tyrosine kinase. SH2 domain: Src-homology 2 domain; SH3 domain: Src-homology 3 domain; Spry: Sprouty.

ER-α36 mediates estrogen-stimulated MAPK/ERK activation and regulates migration, invasion, proliferation in cervical cancer cells

International Nuclear Information System (INIS)

Sun, Qing; Liang, Ying; Zhang, Tianli; Wang, Kun; Yang, Xingsheng

2017-01-01

Objective: Estrogen receptor alpha 36 (ER-α36), a truncated variant of ER-α, is different from other nuclear receptors of the ER-α family. Previous findings indicate that ER-α36 might be involved in cell growth, proliferation, and differentiation in carcinomas and primarily mediates non-genomic estrogen signaling. However, studies on ER-α36 and cervical cancer are rare. This study aimed to detect the expression of ER-α36 in cervical cancer; the role of ER-α36 in 17-β-estradiol (E2)-induced invasion, migration and proliferation of cervical cancer; and their probable molecular mechanisms. Methods: Immunohistochemistry and immunofluorescence were used to determine the location of ER-α36 in cervical cancer tissues and cervical cell lines. CaSki and HeLa cell lines were transfected with lentiviruses to establish stable cell lines with knockdown and overexpression of ER-α36. Wound healing assay, transwell invasion assay, and EdU incorporation proliferation assay were performed to evaluate the migration, invasion, and proliferation ability. The phosphorylation levels of mitogen-activated protein kinases/extracellular signal-regulated kinase (MAPK/ERK) signaling molecules were examined with western blot analysis. Results: ER-α36 expression was detected in both cervical cell lines and cervical cancer tissues. Downregulation of ER-α36 significantly inhibited cell invasion, migration, and proliferation. Moreover, upregulation of ER-α36 increased the invasion, migration, and proliferation ability of CaSki and HeLa cell lines. ER-α36 mediates estrogen-stimulated MAPK/ERK activation. Conclusion: ER-α36 is localized on the plasma membrane and cytoplasm in both cervical cancer tissues and cell lines. ER-α36 mediates estrogen-stimulated MAPK/ERK activation and regulates migration, invasion, proliferation in cervical cancer cells. - Highlights: • ER-α36 is expressed on both cervical cell lines and cervical cancer tissues. • ER-α36 mediates estrogen

Increased limbic phosphorylated extracellular-regulated kinase 1 and 2 expression after chronic stress is reduced by cyclic 17 beta-estradiol administration

NARCIS (Netherlands)

Gerrits, M.; Westenbroek, C.; Koch, T.; Grootkarzijn, A.; Ter Horst, G. J.

2006-01-01

Chronic stress induced neuronal changes that may have consequences for subsequent stress responses. For example, chronic stress in rats rearranges dendritic branching patterns and disturbs the phosphorylation of extracellular-regulated kinase 1 and 2 (ERK) 1/2 throughout the limbic system.

Nitric oxide production by Biomphalaria glabrata haemocytes: effects of Schistosoma mansoni ESPs and regulation through the extracellular signal-regulated kinase pathway

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Kirk Ruth S

2009-04-01

Full Text Available Abstract Background Schistosoma mansoni uses Biomphalaria glabrata as an intermediate host during its complex life cycle. In the snail, the parasite initially transforms from a miracidium into a mother sporocyst and during this process excretory-secretory products (ESPs are released. Nitric oxide (NO and its reactive intermediates play an important role in host defence responses against pathogens. This study therefore aimed to determine the effects of S. mansoni ESPs on NO production in defence cells (haemocytes from schistosome-susceptible and schistosome-resistant B. glabrata strains. As S. mansoni ESPs have previously been shown to inhibit extracellular signal-regulated kinase (ERK phosphorylation (activation in haemocytes from susceptible, but not resistant, B. glabrata the regulation of NO output by ERK in these cells was also investigated. Results Haemocytes from resistant snails challenged with S. mansoni ESPs (20 μg/ml over 5 h displayed an increase in NO production that was 3.3 times greater than that observed for unchallenged haemocytes; lower concentrations of ESPs (0.1–10 μg/ml did not significantly increase NO output. In contrast, haemocytes from susceptible snails showed no significant change in NO output following challenge with ESPs at any concentration used (0.1–20 μg/ml. Western blotting revealed that U0126 (1 μM or 10 μM blocked the phosphorylation (activation status of ERK in haemocytes from both snail strains. Inhibition of ERK signalling by U0126 attenuated considerably intracellular NO production in haemocytes from both susceptible and resistant B. glabrata strains, identifying ERK as a key regulator of NO output in these cells. Conclusion S. mansoni ESPs differentially influence intracellular NO levels in susceptible and resistant B. glabrata haemocytes, possibly through modulation of the ERK signalling pathway. Such effects might facilitate survival of S. mansoni in its intermediate host.

Activation of Extracellular Signal-Regulated Kinase but Not of p38 Mitogen-Activated Protein Kinase Pathways in Lymphocytes Requires Allosteric Activation of SOS

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Jun, Jesse E.; Yang, Ming; Chen, Hang; Chakraborty, Arup K.

2013-01-01

Thymocytes convert graded T cell receptor (TCR) signals into positive selection or deletion, and activation of extracellular signal-related kinase (ERK), p38, and Jun N-terminal protein kinase (JNK) mitogen-activated protein kinases (MAPKs) has been postulated to play a discriminatory role. Two families of Ras guanine nucleotide exchange factors (RasGEFs), SOS and RasGRP, activate Ras and the downstream RAF-MEK-ERK pathway. The pathways leading to lymphocyte p38 and JNK activation are less well defined. We previously described how RasGRP alone induces analog Ras-ERK activation while SOS and RasGRP cooperate to establish bimodal ERK activation. Here we employed computational modeling and biochemical experiments with model cell lines and thymocytes to show that TCR-induced ERK activation grows exponentially in thymocytes and that a W729E allosteric pocket mutant, SOS1, can only reconstitute analog ERK signaling. In agreement with RasGRP allosterically priming SOS, exponential ERK activation is severely decreased by pharmacological or genetic perturbation of the phospholipase Cγ (PLCγ)-diacylglycerol-RasGRP1 pathway. In contrast, p38 activation is not sharply thresholded and requires high-level TCR signal input. Rac and p38 activation depends on SOS1 expression but not allosteric activation. Based on computational predictions and experiments exploring whether SOS functions as a RacGEF or adaptor in Rac-p38 activation, we established that the presence of SOS1, but not its enzymatic activity, is critical for p38 activation. PMID:23589333

MT1-MMP promotes cell growth and ERK activation through c-Src and paxillin in three-dimensional collagen matrix

International Nuclear Information System (INIS)

Takino, Takahisa; Tsuge, Hisashi; Ozawa, Terumasa; Sato, Hiroshi

2010-01-01

Membrane-type 1 matrix metalloproteinase (MT1-MMP) is essential for tumor invasion and growth. We show here that MT1-MMP induces extracellular signal-regulated kinase (ERK) activation in cancer cells cultured in collagen gel, which is indispensable for their proliferation. Inhibition of MT1-MMP by MMP inhibitor or small interfering RNA suppressed activation of focal adhesion kinase (FAK) and ERK in MT1-MMP-expressing cancer cells, which resulted in up-regulation of p21 WAF1 and suppression of cell growth in collagen gel. Cell proliferation was also abrogated by the inhibitor against ERK pathway without affecting FAK phosphorylation. MT1-MMP and integrin α v β 3 were shown to be involved in c-Src activation, which induced FAK and ERK activation in collagen gel. These MT1-MMP-mediated signal transductions were paxillin dependent, as knockdown of paxillin reduced cell growth and ERK activation, and co-expression of MT1-MMP with paxillin induced ERK activation. The results suggest that MT1-MMP contributes to proliferation of cancer cells in the extracellular matrix by activating ERK through c-Src and paxillin.

Transcriptional down-regulation of thromboxane A(2) receptor expression via activation of MAPK ERK1/2, p38/NF-kappaB pathways

DEFF Research Database (Denmark)

Zhang, Wei; Zhang, Yaping; Edvinsson, Lars

2009-01-01

culture of the arteries, VSMC TP receptors were studied by using myography, real-time PCR and immunohistochemistry. We observed that organ culture for 24 and 48 h resulted in depressed TP receptor-mediated contraction in the VSMC, in parallel with decreased TP receptor mRNA and protein expressions....... Phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2), p38 and nuclear factor-kappaB (NF-kappaB) was seen by Western blot within 1-3 h after organ culture. Inhibition of ERK1/2, p38 or NF-kappaB reversed depressed contraction as well as decreased receptor mRNA expression. Actinomycin D...

Transcriptional Down-Regulation of Thromboxane A(2) Receptor Expression via Activation of MAPK ERK1/2, p38/NF-kappaB Pathways

DEFF Research Database (Denmark)

Zhang, Wei; Zhang, Yaping; Edvinsson, Lars

2008-01-01

culture of the arteries, VSMC TP receptors were studied by using myography, real-time PCR and immunohistochemistry. We observed that organ culture for 24 and 48 h resulted in depressed TP receptor-mediated contraction in the VSMC, in parallel with decreased TP receptor mRNA and protein expressions....... Phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2), p38 and nuclear factor-kappaB (NF-kappaB) was seen by Western blot within 1-3 h after organ culture. Inhibition of ERK1/2, p38 or NF-kappaB reversed depressed contraction as well as decreased receptor mRNA expression. Actinomycin D...

The mechanism by which MEK/ERK regulates JNK and p38 activity in polyamine depleted IEC-6 cells during apoptosis

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Bavaria, Mitul N.; Jin, Shi; Ray, Ramesh M.; Johnson, Leonard R.

2014-01-01

Polyamine-depletion inhibited apoptosis by activating ERK1/2, while, preventing JNK1/2 activation. MKP-1 knockdown by SiRNA increased ERK1/2, JNK1/2, and p38 phosphorylation and apoptosis. Therefore, we predicted that polyamines might regulate MKP1 via MEK/ERK and thereby apoptosis. We examined the role of MEK/ERK in the regulation of MKP1 and JNK, and p38 activities and apoptosis. Inhibition of MKP-1 activity with a pharmacological inhibitor, sanguinarine (SA), increased JNK1/2, p38, and ERK1/2 activities without causing apoptosis. However, pre-activation of these kinases by SA significantly increased camptothecin (CPT)-induced apoptosis suggesting different roles for MAPKs during survival and apoptosis. Inhibition of MEK1 activity prevented the expression of MKP-1 protein and augmented CPT-induced apoptosis, which correlated with increased activities of JNK1/2, caspases, and DNA fragmentation. Polyamine depleted cells had higher levels of MKP-1 protein and decreased JNK1/2 activity and apoptosis. Inhibition of MEK1 prevented MKP-1 expression and increased JNK1/2 and apoptosis. Phospho-JNK1/2, phospho-ERK2, MKP-1, and the catalytic subunit of protein phosphatase 2A (PP2Ac) formed a complex in response to TNF/CPT. Inactivation of PP2Ac had no effect on the association of MKP-1 and JNK1. However, inhibition of MKP-1 activity decreased the formation of the MKP-1, PP2Ac and JNK complex. Following inhibition by SA, MKP-1 localized in the cytoplasm, while basal and CPT-induced MKP-1 remained in the nuclear fraction. These results suggest that nuclear MKP-1 translocates to the cytoplasm, binds phosphorylated JNK and p38 resulting in dephosphorylation and decreased activity. Thus, MEK/ERK activity controls the levels of MKP-1 and, thereby, regulates JNK activity in polyamine-depleted cells. PMID:24253595

ERK1/2 activation in human taste bud cells regulates fatty acid signaling and gustatory perception of fat in mice and humans.

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Subramaniam, Selvakumar; Ozdener, Mehmet Hakan; Abdoul-Azize, Souleymane; Saito, Katsuyoshi; Malik, Bilal; Maquart, Guillaume; Hashimoto, Toshihiro; Marambaud, Philippe; Aribi, Mourad; Tordoff, Michael G; Besnard, Philippe; Khan, Naim Akhtar

2016-10-01

Obesity is a major public health problem. An in-depth knowledge of the molecular mechanisms of oro-sensory detection of dietary lipids may help fight it. Humans and rodents can detect fatty acids via lipido-receptors, such as CD36 and GPR120. We studied the implication of the MAPK pathways, in particular, ERK1/2, in the gustatory detection of fatty acids. Linoleic acid, a dietary fatty acid, induced via CD36 the phosphorylation of MEK1/2-ERK1/2-ETS-like transcription factor-1 cascade, which requires Fyn-Src kinase and lipid rafts in human taste bud cells (TBCs). ERK1/2 cascade was activated by Ca 2+ signaling via opening of the calcium-homeostasis modulator-1 (CALHM1) channel. Furthermore, fatty acid-evoked Ca 2+ signaling and ERK1/2 phosphorylation were decreased in both human TBCs after small interfering RNA knockdown of CALHM1 channel and in TBCs from Calhm1 -/- mice. Targeted knockdown of ERK1/2 by small interfering RNA or PD0325901 (MEK1/2 inhibitor) in the tongue and genetic ablation of Erk1 or Calhm1 genes impaired preference for dietary fat in mice. Lingual inhibition of ERK1/2 in healthy volunteers also decreased orogustatory sensitivity for linoleic acid. Our data demonstrate that ERK1/2-MAPK cascade is regulated by the opening of CALHM1 Ca 2+ channel in TBCs to modulate orogustatory detection of dietary lipids in mice and humans.-Subramaniam, S., Ozdener, M. H., Abdoul-Azize, S., Saito, K., Malik, B., Maquart, G., Hashimoto, T., Marambaud, P., Aribi, M., Tordoff, M. G., Besnard, P., Khan, N. A. ERK1/2 activation in human taste bud cells regulates fatty acid signaling and gustatory perception of fat in mice and humans. © FASEB.

Transcutaneous electrical nerve stimulation on Yongquan acupoint reduces CFA-induced thermal hyperalgesia of rats via down-regulation of ERK2 phosphorylation and c-Fos expression.

Science.gov (United States)

Yang, Lin; Yang, Lianxue; Gao, Xiulai

2010-07-01

Activation of extracellular signal-regulated kinase-1/2 (ERK1/2) and its involvement in regulating gene expression in spinal dorsal horn, cortical and subcortical neurons by peripheral noxious stimulation contribute to pain hypersensitivity. Transcutaneous electrical nerve stimulation (TENS) is a treatment used in physiotherapy practice to promote analgesia in acute and chronic inflammatory conditions. In this study, a total number of 114 rats were used for three experiments. Effects of complete Freund's adjuvant (CFA)-induced inflammatory pain hypersensitivity and TENS analgesia on ERK1/2 phosphorylation and c-Fos protein expression were examined by using behavioral test, Western blot, and immunostaining methods. We found that CFA injection caused an area of localized swelling, erythema, hypersensitivity to thermal stimuli, the decreased response time of hind paw licking (HPL), as well as upregulation of c-Fos protein expression and ERK2 phosphorylation in the ipsilateral spinal dorsal horn and the contralateral primary somatosensory area of cortex and the amygdala of rats. TENS on Yongquan acupoint for 20 min produced obvious analgesic effects as demonstrated with increased HPL to thermal stimuli of CFA-treated rats. In addition, TENS application suppressed the CFA-induced ERK2 activation and c-Fos protein expression. These results suggest that down-regulation of ERK2 phosphorylation and c-Fos expression were involved in TENS inhibition on CFA-induced thermal hyperalgesia of rats.

Protein kinase D1 stimulates proliferation and enhances tumorigenesis of MCF-7 human breast cancer cells through a MEK/ERK-dependent signaling pathway

International Nuclear Information System (INIS)

Karam, Manale; Legay, Christine; Auclair, Christian; Ricort, Jean-Marc

2012-01-01

Protein kinase D1, PKD1, is a novel serine/threonine kinase whose altered expression and dysregulation in many tumors as well as its activation by several mitogens suggest that this protein could regulate proliferation and tumorigenesis. Nevertheless, the precise signaling pathways used are still unclear and the potential direct role of PKD1 in tumor development and progression has not been yet investigated. In order to clarify the role of PKD1 in cell proliferation and tumorigenesis, we studied the effects of PKD1 overexpression in a human adenocarcinoma breast cancer cell line, MCF-7 cells. We demonstrated that overexpression of PKD1 specifically promotes MCF-7 cell proliferation through accelerating G0/G1 to S phase transition of the cell cycle. Moreover, inhibition of endogenous PKD1 significantly reduced cell proliferation. Taken together, these results clearly strengthen the regulatory role of PKD1 in cell growth. We also demonstrated that overexpression of PKD1 specifically diminished serum- and anchorage-dependence for proliferation and survival in vitro and allowed MCF-7 cells to form tumors in vivo. Thus, all these data highlight the central role of PKD1 in biological processes which are hallmarks of malignant transformation. Analysis of two major signaling pathways implicated in MCF-7 cell proliferation showed that PKD1 overexpression significantly increased ERK1/2 phosphorylation state without affecting Akt phosphorylation. Moreover, PKD1 overexpression-stimulated cell proliferation and anchorage-independent growth were totally impaired by inhibition of the MEK/ERK kinase cascade. However, neither of these effects was affected by blocking the PI 3-kinase/Akt signaling pathway. Thus, the MEK/ERK signaling appears to be a determining pathway mediating the biological effects of PKD1 in MCF-7 cells. Taken together, all these data demonstrate that PKD1 overexpression increases the aggressiveness of MCF-7 breast cancer cells through enhancing their oncogenic

Exosome uptake depends on ERK1/2-heat shock protein 27 signaling and lipid Raft-mediated endocytosis negatively regulated by caveolin-1.

Science.gov (United States)

Svensson, Katrin J; Christianson, Helena C; Wittrup, Anders; Bourseau-Guilmain, Erika; Lindqvist, Eva; Svensson, Lena M; Mörgelin, Matthias; Belting, Mattias

2013-06-14

The role of exosomes in cancer can be inferred from the observation that they transfer tumor cell derived genetic material and signaling proteins, resulting in e.g. increased tumor angiogenesis and metastasis. However, the membrane transport mechanisms and the signaling events involved in the uptake of these virus-like particles remain ill-defined. We now report that internalization of exosomes derived from glioblastoma (GBM) cells involves nonclassical, lipid raft-dependent endocytosis. Importantly, we show that the lipid raft-associated protein caveolin-1 (CAV1), in analogy with its previously described role in virus uptake, negatively regulates the uptake of exosomes. We find that exosomes induce the phosphorylation of several downstream targets known to associate with lipid rafts as signaling and sorting platforms, such as extracellular signal-regulated kinase-1/2 (ERK1/2) and heat shock protein 27 (HSP27). Interestingly, exosome uptake appears dependent on unperturbed ERK1/2-HSP27 signaling, and ERK1/2 phosphorylation is under negative influence by CAV1 during internalization of exosomes. These findings significantly advance our general understanding of exosome-mediated uptake and offer potential strategies for how this pathway may be targeted through modulation of CAV1 expression and ERK1/2 signaling.

Molecular Mechanism: ERK Signaling, Drug Addiction, and Behavioral Effects.

Science.gov (United States)

Sun, Wei-Lun; Quizon, Pamela M; Zhu, Jun

2016-01-01

Addiction to psychostimulants has been considered as a chronic psychiatric disorder characterized by craving and compulsive drug seeking and use. Over the past two decades, accumulating evidence has demonstrated that repeated drug exposure causes long-lasting neurochemical and cellular changes that result in enduring neuroadaptation in brain circuitry and underlie compulsive drug consumption and relapse. Through intercellular signaling cascades, drugs of abuse induce remodeling in the rewarding circuitry that contributes to the neuroplasticity of learning and memory associated with addiction. Here, we review the role of the extracellular signal-regulated kinase (ERK), a member of the mitogen-activated protein kinase, and its related intracellular signaling pathways in drug-induced neuroadaptive changes that are associated with drug-mediated psychomotor activity, rewarding properties and relapse of drug seeking behaviors. We also discuss the neurobiological and behavioral effects of pharmacological and genetic interferences with ERK-associated molecular cascades in response to abused substances. Understanding the dynamic modulation of ERK signaling in response to drugs may provide novel molecular targets for therapeutic strategies to drug addiction. Copyright © 2016. Published by Elsevier Inc.

BMP6 down-regulates GDNF expression through SMAD1/5 and ERK1/2 signaling pathways in human granulosa-lutein cells.

Science.gov (United States)

Zhang, Xin-Yue; Chang, Hsun-Ming; Taylor, Elizabeth L; Leung, Peter C K; Liu, Rui-Zhi

2018-05-09

Bone morphogenetic protein 6 (BMP6) is a critical regulator of follicular development that is expressed in mammalian oocytes and granulosa cells. Glial cell line-derived neurotrophic factor (GDNF) is an intraovarian neurotrophic factor that plays an essential role in regulating mammalian oocyte maturation. The aim of this study was to investigate the effect of BMP6 on the regulation of GDNF expression and the potential underlying mechanisms. We used an established immortalized human granulosa cell line (SVOG cells) and primary human granulosa-lutein cells as in vitro cell models. Our results showed that BMP6 significantly down-regulated the expression of GDNF in both SVOG and primary human granulosa-lutein cells. Using dual inhibition approaches (kinase receptor inhibitor and small interfering RNA knockdown), our results showed that both ALK2 and ALK3 are involved in BMP6-induced down-regulation of GDNF. In addition, BMP6 induced the phosphorylation of SMAD1/5/8 and ERK1/2 but not AKT or p38. Among three downstream mediators, both SMAD1 and SMAD5 are involved in BMP6-induced down-regulation of GDNF. Moreover, concomitant knockdown of endogenous SMAD4 and inhibition of ERK1/2 activity completely reversed BMP6-induced down-regulation of GDNF, indicating that both SMAD and ERK1/2 signaling pathways are required for the regulatory effect of BMP6 on GDNF expression. Our findings suggest an additional role for an intrafollicular growth factor in regulating follicular function through their paracrine interactions in human granulosa cells.

Different associations of CD45 isoforms with STAT3, PKC and ERK regulate IL-6-induced proliferation in myeloma.

Directory of Open Access Journals (Sweden)

Xu Zheng

Full Text Available In response to interleukin 6 (IL-6 stimulation, both CD45RO and CD45RB, but not CD45RA, translocate to lipid rafts. However, the significance of this distinct translocation and the downstream signals in CD45 isoforms-participated IL-6 signal are not well understood. Using sucrose fractionation, we found that phosphorylated signal transducer and activator of transcription (STAT3 and STAT1 were mainly localized in lipid rafts in response to IL-6 stimulation, despite both STAT3 and STAT1 localizing in raft and non-raft fractions in the presence or absence of IL-6. On the other hand, extracellular signal-regulated kinase (ERK, and phosphorylated ERK were localized in non-raft fractions regardless of the existence of IL-6. The rafts inhibitor significantly impeded the phosphorylation of STAT3 and STAT1 and nuclear translocation, but had little effect on (and only postponing the phosphorylation of ERK. This data suggests that lipid raft-dependent STAT3 and STAT1 pathways are dominant pathways of IL-6 signal in myeloma cells. Interestingly, the phosphorylation level of STAT3 but not STAT1 in CD45+ cells was significantly higher compared to that of CD45- cells, while the phosphorylation level of ERK in CD45+ myeloma cells was relatively low. Furthermore, exogenously expressed CD45RO/RB significantly enhanced STAT3, protein kinase C (PKC and downstream NF-κB activation; however, CD45RA/RB inhibited IL-6-induced ERK phosphorylation. CD45 also enhanced the nuclear localization of STAT3 but not that of STAT1. In response to IL-6 stimulation, CD45RO moved into raft compartments and formed a complex with STAT3 and PKC in raft fraction, while CD45RA remained outside of lipid rafts and formed a complex with ERK in non-raft fraction. This data suggests a different role of CD45 isoforms in IL-6-induced signaling, indicating that while CD45RA/RB seems inhibit the rafts-unrelated ERK pathway, CD45RO/RB may actually work to enhance the rafts-related STAT3 and PKC

Genistein attenuates brain damage induced by transient cerebral ischemia through up-regulation of ERK activity in ovariectomized mice.

Science.gov (United States)

Wang, Shiquan; Wei, Haidong; Cai, Min; Lu, Yan; Hou, Wugang; Yang, Qianzi; Dong, Hailong; Xiong, Lize

2014-01-01

Stroke has severe consequences in postmenopausal women. As replacement therapy of estrogen have various adverse effects and the undermined outcomes. Genistein, a natural phytoestrogen, has been suggested to be a potential neuroprotective agent for such stroke patients. However, the role of genistein and its underlying mechanism in ovariectomized mice has not yet been evaluated. In the present study, ovariectomized mice were treated with genistein (10 mg/kg) or vehicle daily for two weeks before developing transient cerebral ischemia (middle cerebral artery occlusion). The neurological manifestation was evaluated, and infarct volumes were demonstrated by 2,3,5-triphenyltetrazolium chloride staining at 24 h after reperfusion. In addition, phosphorylation of extracellular signal-regulated kinase (ERK) was detected by Western blotting and immunofluorescence staining, and cellular apoptosis was evaluated in the ischemic penumbra. We found that treatment with genistein reduced infarct volumes, improved neurological outcomes and attenuated cellular apoptosis at 24 h after reperfusion. ERK1/2 showed increased phosphorylation by genistein treatment after reperfusion, and an ERK1/2 inhibitor U0126 abolished this protective effect of genistein in terms of infarct volumes, neurological scores and cellular apoptosis. Our findings indicate that treatment with genistein can reduce the severity of subsequent stroke episodes, and that this beneficial function is associated with ERK activation.

TGF-β1 is Involved in Vitamin D-Induced Chondrogenic Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells by Regulating the ERK/JNK Pathway

Directory of Open Access Journals (Sweden)

Xiaorui Jiang

2017-08-01

Full Text Available Background/Aims: Osteoarthritis (OA is characterized by degradation of cartilage, sole cell type of which is chondrocytes. Bone marrow-derived mesenchymal stem cells (BMSCs possess multipotency and can be directionally differentiated into chondrocytes under stimulation. This study was aimed to explore the possible roles of vitamin D and transforming growth factor-β1 (TGF-β1 in the chondrogenic differentiation of BMSCs. Methods: BMSCs were isolated from femurs and tibias of rats and characterized by flow cytometry. After stimulation with vitamin D, BMSC proliferation and migration were measured by Cell Counting Kit-8 (CCK-8 and Transwell assays, respectively. Chondrogenic differentiation was estimated through expression levels of specific markers by qRT-PCR and Western blot analysis. After stable transfection, the effects of aberrantly expressed TGF-β1 on vitamin D-induced alterations, including BMSC viability, migration and chondrogenic differentiation, were all evaluated utilizing CCK-8 assay, Transwell assay, qRT-PCR and Western blot analysis. Finally, the phosphorylation levels of key kinases in the extracellular signal-regulated kinase (ERK and c-Jun N-terminal kinase (JNK pathways were determined by Western blot analysis. Results: Vitamin D remarkably promoted BMSC viability, migration and chondrogenic differentiation. These alterations of BMSCs induced by vitamin D were reinforced by TGF-β1 overexpression while were reversed by TGF-β1 silencing. Additionally, the phosphorylation levels of ERK, JNK and c-Jun were enhanced by TGF-β1 overexpression but were reduced by TGF-β1 knockdown. Conclusion: Vitamin D promoted BMSC proliferation, migration and chondrogenic differentiation. TGF-β1 might be implicated in the vitamin D-induced alterations of BMSCs through regulating ERK/JNK pathway.

Hepatitis C virus E2 protein promotes human hepatoma cell proliferation through the MAPK/ERK signaling pathway via cellular receptors

International Nuclear Information System (INIS)

Zhao Lanjuan; Wang Lu; Ren Hao; Cao Jie; Li Li; Ke Jinshan; Qi Zhongtian

2005-01-01

Dysregulation of mitogen-activated protein kinase (MAPK) signaling pathways by various viruses has been shown to be responsible for viral pathogenicity. The molecular mechanism by which hepatitis C virus (HCV) infection caused human liver diseases has been investigated on the basis of abnormal intracellular signal events. Current data are very limited involved in transmembrane signal transduction triggered by HCV E2 protein. Here we explored regulation of the MAPK/extracellular signal-regulated kinase (MAPK/ERK) signaling pathway by E2 expressed in Chinese hamster oval cells. In human hepatoma Huh-7 cells, E2 specifically activated the MAPK/ERK pathway including downstream transcription factor ATF-2 and greatly promoted cell proliferation. CD81 and low density lipoprotein receptor (LDLR) on the cell surface mediated binding of E2 to Huh-7 cells. The MAPK/ERK activation and cell proliferation driven by E2 were suppressed by blockage of CD81 as well as LDLR. Furthermore, pretreatment with an upstream kinase MEK1/2 inhibitor U0126 also impaired the MAPK/ERK activation and cell proliferation induced by E2. Our results suggest that the MAPK/ERK signaling pathway triggered by HCV E2 via its receptors maintains survival and growth of target cells

ERKs and mitochondria-related pathways are essential for glycyrrhizic acid-mediated neuroprotection against glutamate-induced toxicity in differentiated PC12 cells

International Nuclear Information System (INIS)

Wang, D.; Guo, T.Q.; Wang, Z.Y.; Lu, J.H.; Liu, D.P.; Meng, Q.F.; Xie, J.; Zhang, X.L.; Liu, Y.; Teng, L.S.

2014-01-01

The present study focuses on the neuroprotective effect of glycyrrhizic acid (GA, a major compound separated from Glycyrrhiza Radix, which is a crude Chinese traditional drug) against glutamate-induced cytotoxicity in differentiated PC12 (DPC12) cells. The results showed that GA treatment improved cell viability and ameliorated abnormal glutamate-induced alterations in mitochondria in DPC12 cells. GA reversed glutamate-suppressed B-cell lymphoma 2 levels, inhibited glutamate-enhanced expressions of Bax and cleaved caspase 3, and reduced cytochrome C (Cyto C) release. Exposure to glutamate strongly inhibited phosphorylation of AKT (protein kinase B) and extracellular signal-regulated kinases (ERKs); however, GA pretreatment enhanced activation of ERKs but not AKT. The presence of PD98059 (a mitogen-activated protein/extracellular signal-regulated kinase kinase [MEK] inhibitor) but not LY294002 (a phosphoinositide 3-kinase [PI3K] inhibitor) diminished the potency of GA for improving viability of glutamate-exposed DPC12 cells. These results indicated that ERKs and mitochondria-related pathways are essential for the neuroprotective effect of GA against glutamate-induced toxicity in DPC12 cells. The present study provides experimental evidence supporting GA as a potential therapeutic agent for use in the treatment of neurodegenerative diseases

ERKs and mitochondria-related pathways are essential for glycyrrhizic acid-mediated neuroprotection against glutamate-induced toxicity in differentiated PC12 cells

Energy Technology Data Exchange (ETDEWEB)

Wang, D. [School of Life Sciences, Jilin University, Changchun (China); The State Engineering Laboratory of AIDS Vaccine, Jilin University, Changchun (China); Guo, T.Q. [School of Life Sciences, Jilin University, Changchun (China); Wang, Z.Y. [State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun (China); Lu, J.H.; Liu, D.P.; Meng, Q.F.; Xie, J. [School of Life Sciences, Jilin University, Changchun (China); Zhang, X.L. [Faculty of ScienceNational University of Singapore (Singapore); Liu, Y. [School of Life Sciences, Jilin University, Changchun (China); Teng, L.S. [School of Life Sciences, Jilin University, Changchun (China); The State Engineering Laboratory of AIDS Vaccine, Jilin University, Changchun (China)

2014-07-25

The present study focuses on the neuroprotective effect of glycyrrhizic acid (GA, a major compound separated from Glycyrrhiza Radix, which is a crude Chinese traditional drug) against glutamate-induced cytotoxicity in differentiated PC12 (DPC12) cells. The results showed that GA treatment improved cell viability and ameliorated abnormal glutamate-induced alterations in mitochondria in DPC12 cells. GA reversed glutamate-suppressed B-cell lymphoma 2 levels, inhibited glutamate-enhanced expressions of Bax and cleaved caspase 3, and reduced cytochrome C (Cyto C) release. Exposure to glutamate strongly inhibited phosphorylation of AKT (protein kinase B) and extracellular signal-regulated kinases (ERKs); however, GA pretreatment enhanced activation of ERKs but not AKT. The presence of PD98059 (a mitogen-activated protein/extracellular signal-regulated kinase kinase [MEK] inhibitor) but not LY294002 (a phosphoinositide 3-kinase [PI3K] inhibitor) diminished the potency of GA for improving viability of glutamate-exposed DPC12 cells. These results indicated that ERKs and mitochondria-related pathways are essential for the neuroprotective effect of GA against glutamate-induced toxicity in DPC12 cells. The present study provides experimental evidence supporting GA as a potential therapeutic agent for use in the treatment of neurodegenerative diseases.

Calpain-mediated proteolysis of polycystin-1 C-terminus induces JAK2 and ERK signal alterations

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Kim, Hyunho [Transplantation Research Institute, Seoul National University Medical Research Center, Seoul (Korea, Republic of); Department of Medicine, University of Maryland, Baltimore, MD (United States); Kang, Ah-Young [Transplantation Research Institute, Seoul National University Medical Research Center, Seoul (Korea, Republic of); Department of Medicine, Program of Immunology, Graduate School, Seoul National University, Seoul (Korea, Republic of); Ko, Ah-ra [Clinical Research Center, Samsung Biomedical Research Institute, Seoul (Korea, Republic of); Park, Hayne Cho [Transplantation Research Institute, Seoul National University Medical Research Center, Seoul (Korea, Republic of); Research Coordination Center for Rare Diseases, Seoul National University Hospital, Seoul (Korea, Republic of); So, Insuk [Department of Physiology, Seoul National University College of Medicine, Seoul (Korea, Republic of); Park, Jong Hoon [Department of Biological Science, Sookmyung Women’s University, Seoul (Korea, Republic of); Cheong, Hae Il [Research Coordination Center for Rare Diseases, Seoul National University Hospital, Seoul (Korea, Republic of); Department of Pediatrics, Seoul National University Children’s Hospital, Seoul (Korea, Republic of); Kidney Research Institute, Medical Research Center, Seoul National University College of Medicine, Seoul (Korea, Republic of); Hwang, Young-Hwan [Research Coordination Center for Rare Diseases, Seoul National University Hospital, Seoul (Korea, Republic of); Department of Internal Medicine, Eulji General Hospital, Eulji University College of Medicine, Seoul (Korea, Republic of); and others

2014-01-01

Autosomal dominant polycystic kidney disease (ADPKD), a hereditary renal disease caused by mutations in PKD1 (85%) or PKD2 (15%), is characterized by the development of gradually enlarging multiple renal cysts and progressive renal failure. Polycystin-1 (PC1), PKD1 gene product, is an integral membrane glycoprotein which regulates a number of different biological processes including cell proliferation, apoptosis, cell polarity, and tubulogenesis. PC1 is a target of various proteolytic cleavages and proteosomal degradations, but its role in intracellular signaling pathways remains poorly understood. Herein, we demonstrated that PC1 is a novel substrate for μ- and m-calpains, which are calcium-dependent cysteine proteases. Overexpression of PC1 altered both Janus-activated kinase 2 (JAK2) and extracellular signal-regulated kinase (ERK) signals, which were independently regulated by calpain-mediated PC1 degradation. They suggest that the PC1 function on JAK2 and ERK signaling pathways might be regulated by calpains in response to the changes in intracellular calcium concentration. - Highlights: • Polycystin-1 is a target of ubiquitin-independent degradation by calpains. • The PEST domain is required for calpain-mediated degradation of polycystin-1. • Polycystin-1 may independently regulate JAK2 and ERK signaling pathways.

Inhibition of swallowing reflex following phosphorylation of extracellular signal-regulated kinase in nucleus tractus solitarii neurons in rats with masseter muscle nociception.

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Tsujimura, Takanori; Kitagawa, Junichi; Ueda, Koichiro; Iwata, Koichi

2009-02-06

Pain is associated with swallowing abnormalities in dysphagic patients. Understanding neuronal mechanisms underlying the swallowing abnormalities associated with orofacial abnormal pain is crucial for developing new methods to treat dysphagic patients. However, how the orofacial abnormal pain is involved in the swallowing abnormalities is not known. In order to evaluate neuronal mechanisms of modulation of the swallows by masticatory muscle pain, here we first induced swallows by topical administration of distilled water to the pharyngolaryngeal region. The swallowing reflex was significantly inhibited after capsaicin (10, 30mM) injection into the masseter muscle compared to vehicle injection. Moreover the number of phosphorylated extracellular signal-regulated kinase-like immunoreactive (pERK-LI) neurons in the nucleus tractus solitarii (NTS) was significantly increased in the rats with capsaicin injection into the masseter muscle compared to that with vehicle injection. Rostro-caudal distribution of pERK-LI neurons in the NTS was peaked at the obex level. The capsaicin-induced inhibitory effect on swallowing reflex was reversed after intrathecal administration of mitogen-activated protein kinase (MAPK) kinase (MEK) inhibitor, PD98059. The present findings suggest that phosphorylation of ERK in NTS neurons may be involved in capsaicin-induced inhibition of swallowing reflex.

Chronic tooth pulp inflammation induces persistent expression of phosphorylated ERK (pERK) and phosphorylated p38 (pp38) in trigeminal subnucleus caudalis

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Worsley, M.A.; Allen, C.E.; Billinton, A.; King, A.E.; Boissonade, F.M.

2014-01-01

Background Extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase are transiently phosphorylated (activated) in the spinal cord and trigeminal nucleus by acute noxious stimuli. Acute stimulation of dental pulp induces short-lived ERK activation in trigeminal subnucleus caudalis (Vc), and p38 inhibition attenuates short-term sensitization in Vc induced by acute pulpal stimulation. We have developed a model to study central changes following chronic inflammation of dental pulp that induces long-term sensitization. Here, we examine the effects of chronic inflammation and acute stimulation on the expression of phosphorylated ERK (pERK), phosphorylated p38 (pp38) and Fos in Vc. Results Chronic inflammation alone induced bilateral expression of pERK and pp38 in Vc, but did not induce Fos expression. Stimulation of both non-inflamed and inflamed pulps significantly increased pERK and pp38 bilaterally; expression was greatest in inflamed, stimulated animals, and was similar following 10-min and 60-min stimulation. Stimulation for 60 min, but not 10 min, induced Fos in ipsilateral Vc; Fos expression was significantly greater in inflamed, stimulated animals. pERK was present in both neurons and astrocytes; pp38 was present in neurons and other non-neuronal, non-astrocytic cell types. Conclusions This study provides the first demonstration that chronic inflammation of tooth pulp induces persistent bilateral activation of ERK and p38 within Vc, and that this activation is further increased by acute stimulation. This altered activity in intracellular signaling is likely to be linked to the sensitization that is seen in our animal model and in patients with pulpitis. Our data indicate that pERK and pp38 are more accurate markers of central change than Fos expression. In our model, localization of pERK and pp38 within specific cell types differs from that seen following acute stimulation. This may indicate specific roles for different cell types in

The Role of ERK1/2 in the Development of Diabetic Cardiomyopathy

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Zheng Xu

2016-12-01

Full Text Available Diabetes mellitus is a chronic metabolic condition that affects carbohydrate, lipid and protein metabolism and may impair numerous organs and functions of the organism. Cardiac dysfunction afflicts many patients who experience the oxidative stress of the heart. Diabetic cardiomyopathy (DCM is one of the major complications that accounts for more than half of diabetes-related morbidity and mortality cases. Chronic hyperglycemia and hyperlipidemia from diabetes mellitus cause cardiac oxidative stress, endothelial dysfunction, impaired cellular calcium handling, mitochondrial dysfunction, metabolic disturbances, and remodeling of the extracellular matrix, which ultimately lead to DCM. Although many studies have explored the mechanisms leading to DCM, the pathophysiology of DCM has not yet been fully clarified. In fact, as a potential mechanism, the associations between DCM development and mitogen-activated protein kinase (MAPK activation have been the subjects of tremendous interest. Nonetheless, much remains to be investigated, such as tissue- and cell-specific processes of selection of MAPK activation between pro-apoptotic vs. pro-survival fate, as well as their relation with the pathogenesis of diabetes and associated complications. In general, it turns out that MAPK signaling pathways, such as extracellular signal-regulated kinase 1/2 (ERK1/2, c-Jun N-terminal protein kinase (JNK and p38 MAP kinase, are demonstrated to be actively involved in myocardial dysfunction, hypertrophy, fibrosis and heart failure. As one of MAPK family members, the activation of ERK1/2 has also been known to be involved in cardiac hypertrophy and dysfunction. However, many recent studies have demonstrated that ERK1/2 signaling activation also plays a crucial role in FGF21 signaling and exerts a protective environment of glucose and lipid metabolism, therefore preventing abnormal healing and cardiac dysfunction. The duration, extent, and subcellular compartment of ERK1

Lead acetate induces EGFR activation upstream of SFK and PKCα linkage to the Ras/Raf-1/ERK signaling

International Nuclear Information System (INIS)

Wang, C.-Y.; Wang, Y.-T.; Tzeng, D.-W.; Yang, J.-L.

2009-01-01

Lead acetate (Pb), a probable human carcinogen, can activate protein kinase C (PKC) upstream of extracellular signal-regulated kinase 1 and 2 (ERK1/2). Yet, it remains unclear whether Pb activation of PKC → ERK1/2 involves receptor/non-receptor tyrosine kinases and the Ras signaling transducer. Here we demonstrate a novel mechanism elicited by Pb for transmitting ERK1/2 signaling in CL3 human non-small-cell lung adenocarcinoma cells. Pb induction of higher steady-state levels of Ras-GTP was essential for increasing phospho-Raf-1 S338 and phospho-ERK1/2. Pre-treatment of the cells with a conventional PKC inhibitor Goe6976 or depleting PKCα using specific small interfering RNA blocked Pb induction of Ras-GTP. Pb also activated cellular tyrosine kinases. Specific pharmacological inhibitors, PD153035 for epidermal growth factor receptor (EGFR) and SU6656 for Src family tyrosine kinases (SFK), but not AG1296 for platelet-derived growth factor receptor, could suppress the Pb-induced tyrosine kinases, PKCα, Ras-GTP, phospho-Raf-1 S338 and phospho-ERK1/2. Furthermore, phosphorylation of tyrosines on the EGFR multiple autophosphorylation sites and the conserved SFK autophosphorylation site occurred during exposure of cells to Pb for 1-5 min and 5-30 min, respectively. Intriguingly, Pb activation of EGFR required the intrinsic kinase activity but not dimerization of the receptor. Inhibition of SFK or PKCα activities did not affect EGFR phosphorylation, while knockdown of EGFR blocked SFK phosphorylation and PKCα activation following Pb. Together, these results indicate that immediate activation of EGFR in response to Pb is obligatory for activation of SFK and PKCα and subsequent the Ras-Raf-1-MKK1/2-ERK1/2 signaling cascade

p38 mitogen-activated protein kinase plays a key role in regulating MAPKAPK2 expression

International Nuclear Information System (INIS)

Sudo, Tatsuhiko; Kawai, Kayoko; Matsuzaki, Hiroshi; Osada, Hiroyuki

2005-01-01

One of three major families of the mitogen-activated kinases (MAPK), p38 as well as JNK, has been shown to transduce extracellular stress stimuli into cellular responses by phospho-relay cascades. Among p38 families, p38α is a widely characterized isoform and the biological phenomena are explained by its kinase activity regulating functions of its downstream substrates. However, its specific contributions to each phenomenon are yet not fully elucidated. For better understanding of the role of MAPKs, especially p38α, we utilized newly established mouse fibroblast cell lines originated from a p38α null mouse, namely, a parental cell line without p38α gene locus, knockout of p38α (KOP), Zeosin-resistant (ZKOP), revertant of p38α (RKOP), and Exip revertant (EKOP). EKOP is smaller in size but grows faster than the others. Although comparable amounts of ERK and JNK are expressed in each cell line, ERK is highly phosphorylated in EKOP even in normal culture conditions. Serum stimulation after serum starvation led to ERK phosphorylation in RKOP and ZKOP, but not in EKOP as much. On the contrary, relative phosphorylation level of JNK to total JNK in response to UV was low in RKOP. And its phosphorylation as well as total JNK is slightly lower in EKOP. RKOP is less sensitive to UV irradiation as judged by the survival rate. Stress response upon UV or sorbitol stimuli, leading to mitogen activate protein kinase activated kinase 2 (MAPKAPK2) phosphorylation, was only observed in RKOP. Further experiments reveal that MAPKAPK2 expression is largely suppressed in ZKOP and EKOP. Its expression was recovered by re-introduction of p38α. The loss of MAPKAPK2 expression accompanied by the defect of p38α is confirmed in an embryonic extract prepared from p38α null mice. These data demonstrate that p38 signal pathway is regulated not only by phosphorylation but also by modulation of the expression of its component. Together, we have established cell lines that can be used in

Elevated activation of ERK1 and ERK2 accompany enhanced liver injury following alcohol binge in chronically ethanol-fed rats.

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Aroor, Annayya R; Jackson, Daniel E; Shukla, Shivendra D

2011-12-01

Binge drinking after chronic ethanol consumption is one of the important factors contributing to the progression of steatosis to steatohepatitis. The molecular mechanisms of this effect remain poorly understood. We have therefore examined in rats the effect of single and repeat ethanol binge superimposed on chronic ethanol intake on liver injury, activation of mitogen-activated protein kinases (MAPKs), and gene expression. Rats were chronically treated with ethanol in liquid diet for 4 weeks followed by single ethanol binge (5 gm/kg body weight) or 3 similar repeated doses of ethanol. Serum alcohol and alanine amino transferase (ALT) levels were determined by enzymatic methods. Steatosis was assessed by histology and hepatic triglycerides. Activation of MAPK, 90S ribosomal kinase (RSK), and caspase 3 were evaluated by Western blot. Levels of mRNA for tumor necrosis factor alpha (TNFα), early growth response-1 (egr-1), and plasminogen activator inhibitor-1 (PAI-1) were measured by real-time qRT-PCR. Chronic ethanol treatment resulted in mild steatosis and necrosis, whereas chronic ethanol followed by binge group exhibited marked steatosis and significant increase in necrosis. Chronic binge group also showed significant increase (compared with chronic ethanol alone) in the phosphorylation of extracellular regulated kinase 1 (ERK1), ERK2, and RSK. Phosphorylation of c-Jun N-terminal kinase (JNK) and p38 MAPK did not increase by the binge. Ethanol binge, after chronic ethanol intake, caused increase in mRNA for egr-1 and PAI-1, but not TNFα. Chronic ethanol exposure increases the susceptibility of rat liver to increased injury by 1 or 3 repeat binge. Among other alterations, the activated levels of ERK1, and more so ERK2, were remarkably amplified by binge suggesting a role of these isotypes in the binge amplification of the injury. In contrast, p38 MAPK and JNK1/2 activities were not amplified. These binge-induced changes were also reflected in the increases in the

ERK5 signaling gets XIAPed: a role for ubiquitin in the disassembly of a MAPK cascade

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Klein, Aileen M; Cobb, Melanie H

2014-01-01

Mitogen-activated protein kinase (MAPK) cascades are tightly controlled through a series of well-characterized phospho-regulatory events. In this issue, Takeda et al (2014) identify the inhibitor of apoptosis protein, XIAP, as a key regulator of ERK5 activation via uncoupling of upstream kinase activity by non-degradative ubiquitination. PMID:25012518

Angiotensin II modulates interleukin-1β-induced inflammatory gene expression in vascular smooth muscle cells via interfering with ERK-NF-κB crosstalk

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Xu, Shanqin; Zhi, Hui; Hou, Xiuyun; Jiang, Bingbing

2011-01-01

Highlights: → We examine how angiotensin II modulates ERK-NF-κB crosstalk and gene expression. → Angiotensin II suppresses IL-1β-induced prolonged ERK and NF-κB activation. → ERK-RSK1 signaling is required for IL-1β-induced prolonged NF-κB activation. → Angiotensin II modulates NF-κB responsive genes via regulating ERK-NF-κB crosstalk. → ERK-NF-κB crosstalk is a novel mechanism regulating inflammatory gene expression. -- Abstract: Angiotensin II is implicated in cardiovascular diseases, which is associated with a role in increasing vascular inflammation. The present study investigated how angiotensin II modulates vascular inflammatory signaling and expression of inducible nitric oxide synthase (iNOS) and vascular cell adhesion molecule (VCAM)-1. In cultured rat aortic vascular smooth muscle cells (VSMCs), angiotensin II suppressed interleukin-1β-induced prolonged phosphorylation of extracellular signal-regulated kinase (ERK) and ribosomal S6 kinase (RSK)-1, and nuclear translocation of nuclear factor (NF)-κB, leading to decreased iNOS but enhanced VCAM-1 expression, associated with an up-regulation of mitogen-activated protein kinase phosphatase-1 expression. Knock-down of RSK1 selectively down regulated interleukin-1β-induced iNOS expression without influencing VCAM-1 expression. In vivo experiments showed that interleukin-1β, iNOS, and VCAM-1 expression were detectable in the aortic arches of both wild-type and apolipoprotein E-deficient (ApoE -/- ) mice. VCAM-1 and iNOS expression were higher in ApoE -/- than in wild type mouse aortic arches. Angiotensin II infusion (3.2 mg/kg/day, for 6 days, via subcutaneous osmotic pump) in ApoE -/- mice enhanced endothelial and adventitial VCAM-1 and iNOS expression, but reduced medial smooth muscle iNOS expression associated with reduced phosphorylation of ERK and RSK-1. These results indicate that angiotensin II can differentially modulate inflammatory gene expression in aortic smooth muscle cells

Ectopic ERK Expression Induces Phenotypic Conversion of C10 Cells and Alters DNA Methyltransferase Expression

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Sontag, Ryan L.; Weber, Thomas J.

2012-05-04

In some model systems constitutive extracellular signal regulated kinase (ERK) activation is sufficient to promote an oncogenic phenotype. Here we investigate whether constitutive ERK expression influences phenotypic conversion in murine C10 type II alveolar epithelial cells. C10 cells were stably transduced with an ERK1-green fluorescent protein (ERK1-GFP) chimera or empty vector and ectopic ERK expression was associated with the acquisition of soft agar focus-forming potential in late passage, but not early passage cells. Late passage ERK1-GFP cells exhibited a significant increase in the expression of DNA methyl transferases (DNMT1 and 3b) and a marked increase in sensitivity to 5-azacytidine (5-azaC)-mediated toxicity, relative to early passage ERK1-GFP cells and vector controls. The expression of xeroderma pigmentosum complementation group A (XPA) and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) were significantly increased in late passage cells, suggesting enhanced DNA damage recognition and repair activity which we interpret as a reflection of genomic instability. Phospho-ERK levels were dramatically decreased in late passage ERK1-GFP cells, relative to early passage and vector controls, and phospho-ERK levels were restored by treatment with sodium orthovanadate, indicating a role for phosphatase activity in this response. Collectively these observations suggest that ectopic ERK expression promotes phenotypic conversion of C10 cells that is associated with latent effects on epigenetic programming and phosphatase activities.

The ERK MAP kinase-PEA3/ETV4-MMP-1 axis is operative in oesophageal adenocarcinoma

LENUS (Irish Health Repository)

Keld, Richard

2010-12-09

Abstract Background Many members of the ETS-domain transcription factor family are important drivers of tumourigenesis. In this context, their activation by Ras-ERK pathway signaling is particularly relevant to the tumourigenic properties of many ETS-domain transcription factors. The PEA3 subfamily of ETS-domain transcription factors have been implicated in tumour metastasis in several different cancers. Results Here, we have studied the expression of the PEA3 subfamily members PEA3\\/ETV4 and ER81\\/ETV1 in oesophageal adenocarcinomas and determined their role in oesophageal adenocarcinoma cell function. PEA3 plays an important role in controlling both the proliferation and invasive properties of OE33 oesophageal adenocarcinoma cells. A key target gene is MMP-1. The ERK MAP kinase pathway activates PEA3 subfamily members and also plays a role in these PEA3 controlled events, establishing the ERK-PEA3-MMP-1 axis as important in OE33 cells. PEA3 subfamily members are upregulated in human adenocarcinomas and expression correlates with MMP-1 expression and late stage metastatic disease. Enhanced ERK signaling is also more prevalent in late stage oesophageal adenocarcinomas. Conclusions This study shows that the ERK-PEA3-MMP-1 axis is upregulated in oesophageal adenocarcinoma cells and is a potentially important driver of the metastatic progression of oesophageal adenocarcinomas.

Requirement of ERα and basal activities of EGFR and Src kinase in Cd-induced activation of MAPK/ERK pathway in human breast cancer MCF-7 cells

Energy Technology Data Exchange (ETDEWEB)

Song, Xiulong, E-mail: songxiulong@hotmail.com; Wei, Zhengxi; Shaikh, Zahir A., E-mail: zshaikh@uri.edu

2015-08-15

Cadmium (Cd) is a common environmental toxicant and an established carcinogen. Epidemiological studies implicate Cd with human breast cancer. Low micromolar concentrations of Cd promote proliferation of human breast cancer cells in vitro. The growth promotion of breast cancer cells is associated with the activation of MAPK/ERK pathway. This study explores the mechanism of Cd-induced activation of MAPK/ERK pathway. Specifically, the role of cell surface receptors ERα, EGFR, and Src kinase was evaluated in human breast cancer MCF-7 cells treated with 1–3 μM Cd. The activation of ERK was studied using a serum response element (SRE) luciferase reporter assay. Receptor phosphorylation was detected by Western blot analyses. Cd treatment increased both the SRE reporter activity and ERK1/2 phosphorylation in a concentration-dependent manner. Cd treatment had no effect on reactive oxygen species (ROS) generation. Also, blocking the entry of Cd into the cells with manganese did not diminish Cd-induced activation of MAPK/ERK. These results suggest that the effect of Cd was likely not caused by intracellular ROS generation, but through interaction with the membrane receptors. While Cd did not appear to activate either EGFR or Src kinase, their inhibition completely blocked the Cd-induced activation of ERK as well as cell proliferation. Similarly, silencing ERα with siRNA or use of ERα antagonist blocked the effects of Cd. Based on these results, it is concluded that not only ERα, but also basal activities of EGFR and Src kinase are essential for Cd-induced signal transduction and activation of MAPK/ERK pathway for breast cancer cell proliferation. - Highlights: • Low micromolar concentrations of Cd rapidly activate ERK1/2 in MCF-7 cells. • Signal transduction and resulting cell proliferation require EGFR, ERα, and Src. • These findings implicate Cd in promotion of breast cancer.

Membrane-Type 1 Matrix Metal loproteinase Is Regulated by Sp1 through the Differential Activation of AKT, JNK, and ERK Pathways in Human Prostate Tumor Cells

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Isis C. Sroka

2007-05-01

Full Text Available We and other investigators have previously shown that membrane-type 1 matrix metalloproteinase (MT1-MMP is overexpressed in invasive prostate cancer cells. However, the mechanism for this expression is not known. Here, we show that MT1-MMP is minimally expressed in nonmalignant primary prostate cells, moderately expressed in DU-145 cells, and highly expressed in invasive PC-3 and PC-3N cells. Using human MT1-MMP promoter reporter plasmids and mobility shift assays, we show that Spi regulates MT1-MMP expression in DU-145, PC-3, and PC-3N cells and in PC3-N cells using chromatin immunoprecipitation analysis and silencing RNA. Investigation of signaling pathway showed that DU-145 cells express constitutively phosphorylated extracellular stress-regulated kinase (ERK, whereas PC-3 and PC-3N cells express constitutively phosphorylated AKT/PKB and c-Jun NH2 terminal kinase (JNK. We show that MT1-MMP and Spi levels are decreased in PC-3 and PC-3N cells when phosphatidylinositol-3 kinase and JNK are inhibited, and that MT1-MMP levels are decreased in DU-145 cells when MEK is inhibited. Transient transfection of PC-3 and PC-3N cells with a dominant-negative JNK or p85, and of DU-145 cells with a dominant negative ERK, reduces MT1-MMP promoter activity. These results indicate differential signaling control of Spi-mediated transcriptional regulation of MT1-MMP in prostate cancer cell lines.

FGFR2c-mediated ERK-MAPK activity regulates coronal suture development

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Pfaff, Miles J.; Xue, Ke; Li, Li; Horowitz, Mark C.; Steinbacher, Derek M.; Eswarakumar, Jacob V.P.

2017-01-01

Fibroblast growth factor receptor 2 (FGFR2) signaling is critical for proper craniofacial development. A gain-of-function mutation in the 2c splice variant of the receptor’s gene is associated with Crouzon syndrome, which is characterized by craniosynostosis, the premature fusion of one or more of the cranial vault sutures, leading to craniofacial maldevelopment. Insight into the molecular mechanism of craniosynostosis has identified the ERK-MAPK signaling cascade as a critical regulator of suture patency. The aim of this study is to investigate the role of FGFR2c-induced ERK-MAPK activation in the regulation of coronal suture development. Loss-of-function and gain-of-function Fgfr2c mutant mice have overlapping phenotypes, including coronal synostosis and craniofacial dysmorphia. In vivo analysis of coronal sutures in loss-of-function and gain-of-function models demonstrated fundamentally different pathogenesis underlying coronal suture synostosis. Calvarial osteoblasts from gain-of-function mice demonstrated enhanced osteoblastic function and maturation with concomitant increase in ERK-MAPK activation. In vitro inhibition with the ERK protein inhibitor U0126 mitigated ERK protein activation levels with a concomitant reduction in alkaline phosphatase activity. This study identifies FGFR2c-mediated ERK-MAPK signaling as a key mediator of craniofacial growth and coronal suture development. Furthermore, our results solve the apparent paradox between loss-of-function and gain-of-function FGFR2c mutants with respect to coronal suture synostosis. PMID:27034231

IL-1β-Induced Accumulation of Amyloid: Macroautophagy in Skeletal Muscle Depends on ERK

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Karsten Schmidt

2017-01-01

Full Text Available The pathology of inclusion body myositis (IBM involves an inflammatory response and β-amyloid deposits in muscle fibres. It is believed that MAP kinases such as the ERK signalling pathway mediate the inflammatory signalling in cells. Further, there is evidence that autophagic activity plays a crucial role in the pathogenesis of IBM. Using a well established in vitro model of IBM, the autophagic pathway, MAP kinases, and accumulation of β-amyloid were examined. We demonstrate that stimulation of muscle cells with IL-1β and IFN-γ led to an increased phosphorylation of ERK. The ERK inhibitor PD98059 diminished the expression of proinflammatory markers as well as the accumulation of β-amyloid. In addition, IL-1β and IFN-γ led to an increase of autophagic activity, upregulation of APP, and subsequent accumulation of β-sheet aggregates. Taken together, the data demonstrate that the ERK pathway contributes to formation of β-amyloid and regulation of autophagic activity in muscle cells exposed to proinflammatory cell stress. This suggests that ERK serves as an important mediator between inflammatory mechanisms and protein deposition in skeletal muscle and is a crucial element of the pathology of IBM.

Curcumin protects cortical neurons against oxygen and glucose deprivation/reoxygenation injury through flotillin-1 and extracellular signal-regulated kinase1/2 pathway.

Science.gov (United States)

Lu, Zhengyu; Liu, Yanping; Shi, Yang; Shi, Xinjie; Wang, Xin; Xu, Chuan; Zhao, Hong; Dong, Qiang

2018-02-05

In this study, we provided evidence that curcumin could be a promising therapeutic agent for ischemic stroke by activating neuroprotective signaling pathways. Post oxygen and glucose deprivation/reoxygenation (OGD/R), primary mouse cortical neurons treated with curcumin exhibited a significant decrease in cell death, LDH release and enzyme caspase-3 activity under OGD/R circumstances, which were abolished by flotillin-1 downregulation or extracellular signal-regulated kinase (ERK) inhibitor. Moreover, flotillin-1 knockdown led to suppression of curcumin-mediated ERK phosphorylation under OGD/R condition. Based on these findings, we concluded that curcumin could confer neuroprotection against OGD/R injury through a novel flotillin-1 and ERK1/2 pathway. Copyright © 2018 Elsevier Inc. All rights reserved.

Lithium attenuates cannabinoid-induced dependence in the animal model: involvement of phosphorylated ERK1/2 and GSK-3β signaling pathways.

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Hamid Reza Rahimi

2014-09-01

Full Text Available Cannabis is one of the most banned drugs in the world. Cannabinoid-induced dependence or withdrawal signs are indicated by the result of complex molecular mechanisms including upstream protein kinases (PKs, such as an extracellular signal regulated kinase1/2 (ERK1/2 and downstream glycogen synthase kinase-3β (GSK-3β, which lead to neuronal plasticity. In this study, we examined the protective effect of lithium (Li as a potent ERK1/2 and GSK-3β modulator to prevent the development of dependence on cannabinoids. For this purpose, rats were treated twice daily with increasing doses of WIN 55,212-2 (WIN, 2-8 mg/kg, intraperitoneally (i.p., for five consecutive days. AM251 (AM, 2 mg/kg, a cannabinoid antagonist, was injected i.p to induce manifestations of abstinence in rat dependency on WIN, and the subsequent withdrawal signs were recorded. To evaluate the preventive effect of Li, the rats were pre-treated with Li (10 mg/kg, i.p. twice daily, 30 minutes before every injection of WIN. SL327, as an ERK1/2 inhibitor, was also injected (SL, 50 mg/kg, i.p. 30 minutes before the last doses of WIN in separate groups. The p-ERK1/2, total ERK1/2, p-GSK-3β and total GSK-3β expressions were determined with Western blot method after 60 minutes, prior to the Li, WIN or AM injections. Li and SL pre-treatment attenuated the global withdrawal signs in regarding their modulation effect on the up-regulation of p-ERK1/2 cascade enhanced by AM injection. Furthermore, the p-GSK-3β expression was up-regulated with SL and Li pre-treatment against AM injection, without alteration on the total contents of ERK1/2 and GSK-3β level. Therefore, p-ERK1/2 and p-GSK-3β pathways are involved in the cannabinoid-induced dependence. However, no crosstalk was indicated between these two pathways. In conclusion, Li neuroprotectionwith regard to cannabinoid abstinence may occur through the regulation of the p-ERK1/2 cascade inconsequent of p-GSK-3β signaling pathways in rats.

AVS-1357 inhibits melanogenesis via prolonged ERK activation.

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Kim, Dong-Seok; Lee, Hyun-Kyung; Park, Seo-Hyoung; Chae, Chong Hak; Park, Kyoung-Chan

2009-08-01

In this study, we demonstrated that a derivative of imidazole, AVS-1357, is a novel skin-whitening compound. AVS-1357 was found to significantly inhibit melanin production in a dose-dependent manner; however, it did not directly inhibit tyrosinase. Furthermore, we found that AVS-1357 induced prolonged activation of extracellular signal-regulated kinase (ERK) and Akt, while it downregulated microphthalmia-associated transcription factor (MITF) and tyrosinase. It has been reported that the activation of ERK and/or Akt is involved in melanogenesis. Therefore, we examined the effects of AVS-1357 on melanogenesis in the absence or presence of PD98059 (a specific inhibitor of the ERK pathway) and/or LY294002 (a specific inhibitor of the Akt pathway). PD98059 dramatically increased melanogenesis, whereas LY294002 had no effect. Furthermore, PD98059 attenuated AVS-1357 induced ERK activation, as well as the downregulation of MITF and tyrosinase. These findings suggest that the effects of AVS-1357 occur via downregulation of MITF and tyrosinase, which is caused by AVS-1357-induced prolonged ERK activation. Taken together, our results indicate that AVS-1357 has the potential as a new skin whitening agent.

Structure-Guided Strategy for the Development of Potent Bivalent ERK Inhibitors

Energy Technology Data Exchange (ETDEWEB)

Lechtenberg, Bernhard C. [Cancer; Mace, Peter D. [Cancer; Sessions, E. Hampton [Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827, United States; Williamson, Robert [Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827, United States; Stalder, Romain [Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827, United States; Wallez, Yann [Cancer; Roth, Gregory P. [Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827, United States; Riedl, Stefan J. [Cancer; Pasquale, Elena B. [Cancer; Pathology

2017-06-13

ERK is the effector kinase of the RAS-RAF-MEK-ERK signaling cascade, which promotes cell transformation and malignancy in many cancers and is thus a major drug target in oncology. Kinase inhibitors targeting RAF or MEK are already used for the treatment of certain cancers, such as melanoma. Although the initial response to these drugs can be dramatic, development of drug resistance is a major challenge, even with combination therapies targeting both RAF and MEK. Importantly, most resistance mechanisms still rely on activation of the downstream effector kinase ERK, making it a promising target for drug development efforts. Here, we report the design and structural/functional characterization of a set of bivalent ERK inhibitors that combine a small molecule inhibitor that binds to the ATP-binding pocket with a peptide that selectively binds to an ERK protein interaction surface, the D-site recruitment site (DRS). Our studies show that the lead bivalent inhibitor, SBP3, has markedly improved potency compared to the small molecule inhibitor alone. Unexpectedly, we found that SBP3 also binds to several ERK-related kinases that contain a DRS, highlighting the importance of experimentally verifying the predicted specificity of bivalent inhibitors. However, SBP3 does not target any other kinases belonging to the same CMGC branch of the kinome. Additionally, our modular click chemistry inhibitor design facilitates the generation of different combinations of small molecule inhibitors with ERK-targeting peptides.

Localization of active, dually phosphorylated extracellular signal-regulated kinase 1 and 2 in colorectal cancer with or without activating BRAF and KRAS mutations

DEFF Research Database (Denmark)

Holck, Susanne; Bonde, Jesper; Pedersen, Helle

2016-01-01

Colorectal cancers (CRC) often show activating mutations of the KRAS or BRAF genes, which stimulate the extracellular signal-regulated kinase (ERK) pathway, thus increasing cell proliferation and inhibiting apoptosis. However, immunohistochemical results on ERK activation in such tumors differ...... detectable increases in phosphorylation of ERK (pERK), we stained biopsies from 36 CRC patients with activating mutations in the BRAF gene (BRAFV600E: BRAF(m)), the KRAS gene (KRAS(m)) or in neither (BRAF/KRAS(n)) with this optimized method. Staining was scored in blind-coded specimens by two observers....... Staining of stromal cells was used as a positive control. BRAF(m) or KRAS(m) tumors did not show higher staining scores than BRAF/KRAS(n) tumors. Although BRAFV600E staining occurred in over 90% of cancer cells in all 9 BRAF(m) tumors, 3 only showed staining for pERK in less than 10% of cancer cell nuclei...

Sex differences in social interaction behaviors in rats are mediated by extracellular signal-regulated kinase 2 expression in the medial prefrontal cortex

Science.gov (United States)

Carrier, Nicole; Kabbaj, Mohamed

2012-01-01

Considerable sex differences occur in the incidence and prevalence of anxiety disorders where women are more anxious than men, particularly in situations where social interaction is required. In preclinical studies, the social interaction test represents a valid animal model to study sex differences in social anxiety. Indeed, female rats engage less in conspecific interactions than their male counterparts, which are behaviors indicative of higher social anxiety in female rats. In this work, we implicated extracellular signal regulated kinase 2 (ERK2) in the medial prefrontal cortex (mPFC) in mediating social interaction. Indeed, female rats’ had lower ERK2 expression compared to male rats, and overexpression of ERK2 in the mPFC increases their social interaction to the level seen in their male counterparts. These data indicate that the sexually dimorphic expression of ERK2 mediates social anxiety-like behaviors. PMID:22521590

Erk5 inhibits endothelial migration via KLF2-dependent down-regulation of PAK1.

Science.gov (United States)

Komaravolu, Ravi K; Adam, Christian; Moonen, Jan-Renier A J; Harmsen, Martin C; Goebeler, Matthias; Schmidt, Marc

2015-01-01

The MEK5/Erk5 pathway mediates beneficial effects of laminar flow, a major physiological factor preventing vascular dysfunction. Forced Erk5 activation induces a protective phenotype in endothelial cell (EC) that is associated with a dramatically decreased migration capacity of those cells. Transcriptional profiling identified the Krüppel-like transcription factors KLF2 and KLF4 as central mediators of Erk5-dependent gene expression. However, their downstream role regarding migration is unclear and relevant secondary effectors remain elusive. Here, we further investigated the mechanism underlying Erk5-dependent migration arrest in ECs. Our experiments reveal KLF2-dependent loss of the pro-migratory Rac/Cdc42 mediator, p21-activated kinase 1 (PAK1), as an important mechanism of Erk5-induced migration inhibition. We show that endothelial Erk5 activation by expression of a constitutively active MEK5 mutant, by statin treatment, or by application of laminar shear stress strongly decreased PAK1 mRNA and protein expression. Knockdown of KLF2 but not of KLF4 prevented Erk5-mediated PAK1 mRNA inhibition, revealing KLF2 as a novel PAK1 repressor in ECs. Importantly, both PAK1 re-expression and KLF2 knockdown restored the migration capacity of Erk5-activated ECs underscoring their functional relevance downstream of Erk5. Our data provide first evidence for existence of a previously unknown Erk5/KLF2/PAK1 axis, which may limit undesired cell migration in unperturbed endothelium and lower its sensitivity for migratory cues that promote vascular diseases including atherosclerosis. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

Molecular mechanism of ERK dephosphorylation by striatal-enriched protein tyrosine phosphatase (STEP)

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Li, Hui; Li, Kang-shuai; Su, Jing; Chen, Lai-Zhong; Xu, Yun-Fei; Wang, Hong-Mei; Gong, Zheng; Cui, Guo-Ying; Yu, Xiao; Wang, Kai; Yao, Wei; Xin, Tao; Li, Min-Yong; Xiao, Kun-Hong; An, Xiao-fei; Huo, Yuqing; Xu, Zhi-gang; Sun, Jin-Peng; Pang, Qi

2013-01-01

Striatal-enriched tyrosine phosphatase (STEP) is an important regulator of neuronal synaptic plasticity, and its abnormal level or activity contributes to cognitive disorders. One crucial downstream effector and direct substrate of STEP is extracellular signal-regulated protein kinase (ERK), which has important functions in spine stabilisation and action potential transmission. The inhibition of STEP activity toward phospho-ERK has the potential to treat neuronal diseases, but the detailed mechanism underlying the dephosphorylation of phospho-ERK by STEP is not known. Therefore, we examined STEP activity toward pNPP, phospho-tyrosine-containing peptides, and the full-length phospho-ERK protein using STEP mutants with different structural features. STEP was found to be a highly efficient ERK tyrosine phosphatase that required both its N-terminal regulatory region and key residues in its active site. Specifically, both KIM and KIS of STEP were required for ERK interaction. In addition to the N-terminal KIS region, S245, hydrophobic residues L249/L251, and basic residues R242/R243 located in the KIM region were important in controlling STEP activity toward phospho-ERK. Further kinetic experiments revealed subtle structural differences between STEP and HePTP that affected the interactions of their KIMs with ERK. Moreover, STEP recognised specific positions of a phospho-ERK peptide sequence through its active site, and the contact of STEP F311 with phospho-ERK V205 and T207 were crucial interactions. Taken together, our results not only provide the information for interactions between ERK and STEP, but will also help in the development of specific strategies to target STEP-ERK recognition, which could serve as a potential therapy for neurological disorders. PMID:24117863

Retinoic Acid Modulates Interferon-γ Production by Hepatic Natural Killer T Cells via Phosphatase 2A and the Extracellular Signal-Regulated Kinase Pathway

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Chang, Heng-Kwei

2015-01-01

Retinoic acid (RA), an active metabolite converted from vitamin A, plays an active role in immune function, such as defending against infections and immune regulation. Although RA affects various types of immune cells, including antigen-presenting cells, B lymphocytes, and T lymphocytes, whether it affects natural killer T (NKT) cells remain unknown. In this study, we found that RA decreased interferon (IFN)-γ production by activated NKT cells through T-cell receptor (TCR) and CD28. We also found that RA reduced extracellular signal-regulated kinase (ERK) phosphorylation, but increased phosphatase 2A (PP2A) activity in TCR/CD28-stimulated NKT cells. The increased PP2A activity, at least partly, contributed to the reduction of ERK phosphorylation. Since inhibition of ERK activation decreases IFN-γ production by TCR/CD28-stimulated NKT cells, RA may downregulate IFN-γ production by TCR/CD28-stimulated NKT cells through the PP2A-ERK pathway. Our results demonstrated a novel function of RA in modulating the IFN-γ expression by activated NKT cells. PMID:25343668

CacyBP/SIP binds ERK1/2 and affects transcriptional activity of Elk-1

International Nuclear Information System (INIS)

Kilanczyk, Ewa; Filipek, Slawomir; Jastrzebska, Beata; Filipek, Anna

2009-01-01

In this work we showed for the first time that mouse CacyBP/SIP interacts with extracellular signal regulated kinases 1 and 2 (ERK1/2). We also established that a calcium binding protein, S100A6, competes for this interaction. Moreover, the E217K mutant of CacyBP/SIP does not bind significantly to ERK1/2 although it retains the ability to interact with S100A6. Molecular modeling shows that the E217K mutation in the 189-219 CacyBP/SIP fragment markedly changes its electrostatic potential, suggesting that the binding with ERK1/2 might have an electrostatic character. We also demonstrate that CacyBP/SIP-ERK1/2 interaction inhibits phosphorylation of the Elk-1 transcription factor in vitro and in the nuclear fraction of NB2a cells. Altogether, our data suggest that the binding of CacyBP/SIP with ERK1/2 might regulate Elk-1 phosphorylation/transcriptional activity and that S100A6 might further modulate this effect via Ca 2+ -dependent interaction with CacyBP/SIP and competition with ERK1/2.

Kaempferol induces chondrogenesis in ATDC5 cells through activation of ERK/BMP-2 signaling pathway.

Science.gov (United States)

Nepal, Manoj; Li, Liang; Cho, Hyoung Kwon; Park, Jong Kun; Soh, Yunjo

2013-12-01

Endochondral bone formation occurs when mesenchymal cells condense to differentiate into chondrocytes, the primary cell types of cartilage. The aim of the present study was to identify novel factors regulating chondrogenesis. We investigated whether kaempferol induces chondrogenic differentiation in clonal mouse chondrogenic ATDC5 cells. Kaempferol treatment stimulated the accumulation of cartilage nodules in a dose-dependent manner. Kaempferol-treated ATDC5 cells stained more intensely with alcian blue staining than control cells, suggesting greater synthesis of matrix proteoglycans in the kaempferol-treated cells. Similarly, kaempferol induced greater activation of alkaline phosphatase activity than control cells, and it enhanced the expression of chondrogenic marker genes, such as collagen type I, collagen type X, OCN, Runx2, and Sox9. Kaempferol induced an acute activation of extracellular signal-regulated kinase (ERK) but not c-jun N-terminal kinase or p38 MAP kinase. PD98059, an inhibitor of MAPK/ERK, decreased in stained cells treated with kaempferol. Furthermore, kaempferol greatly expressed the protein and mRNA levels of BMP-2, suggesting chondrogenesis was stimulated via a BMP-2 pathway. Taken together, our results suggest that kaempferol has chondromodulating effects via an ERK/BMP-2 signaling pathway and could potentially be used as a therapeutic agent for bone growth disorders. Copyright © 2013 Elsevier Ltd. All rights reserved.

Nicotine shifts the temporal activation of hippocampal protein kinase A and extracellular signal-regulated kinase 1/2 to enhance long-term, but not short-term, hippocampus-dependent memory.

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Gould, Thomas J; Wilkinson, Derek S; Yildirim, Emre; Poole, Rachel L F; Leach, Prescott T; Simmons, Steven J

2014-03-01

Acute nicotine enhances hippocampus-dependent learning through nicotine binding to β2-containing nicotinic acetylcholine receptors (nAChRs), but it is unclear if nicotine is targeting processes involved in short-term memory (STM) leading to a strong long-term memory (LTM) or directly targeting LTM. In addition, the molecular mechanisms involved in the effects of nicotine on learning are unknown. Previous research indicates that protein kinase A (PKA), extracellular signal-regulated kinase 1/2 (ERK1/2), and protein synthesis are crucial for LTM. Therefore, the present study examined the effects of nicotine on STM and LTM and the involvement of PKA, ERK1/2, and protein synthesis in the nicotine-induced enhancement of hippocampus-dependent contextual learning in C57BL/6J mice. The protein synthesis inhibitor anisomycin impaired contextual conditioning assessed at 4 h but not 2 h post-training, delineating time points for STM (2 h) and LTM (4 h and beyond). Nicotine enhanced contextual conditioning at 4, 8, and 24 h but not 2 h post-training, indicating nicotine specifically enhances LTM but not STM. Furthermore, nicotine did not rescue deficits in contextual conditioning produced by anisomycin, suggesting that the nicotine enhancement of contextual conditioning occurs through a protein synthesis-dependent mechanism. In addition, inhibition of dorsal hippocampal PKA activity blocked the effect of acute nicotine on learning, and nicotine shifted the timing of learning-related PKA and ERK1/2 activity in the dorsal and ventral hippocampus. Thus, the present results suggest that nicotine specifically enhances LTM through altering the timing of PKA and ERK1/2 signaling in the hippocampus, and suggests that the timing of PKA and ERK1/2 activity could contribute to the strength of memories. Copyright © 2014 Elsevier Inc. All rights reserved.

Lindersin B from Lindernia crustacea induces neuritogenesis by activation of tyrosine kinase A/phosphatidylinositol 3 kinase/extracellular signal-regulated kinase signaling pathway.

Science.gov (United States)

Cheng, Lihong; Ye, Ying; Xiang, Lan; Osada, Hiroyuki; Qi, Jianhua

2017-01-15

Neurotrophic factors such as nerve growth factor (NGF) play important roles in nervous system. NGF is a potential therapeutic drug for treatment of neurodegenerative diseases. However, because of physicochemical property, NGF cannot pass through the blood-brain barrier (BBB). Hence, small molecules which exhibit NGF-mimic activity and can pass through the BBB are considered to be promising drug candidates for treatment of such diseases. The present study was designed to isolate NGF-mimic substance from extract of natural products, determine their structures and investigate mechanism of action of the active substance. Extract of Lindernia crustacean was partitioned between water and ethyl acetate to obtain water layer and ethyl acetate layer samples, respectively, and then evaluated their neuritogenic activity in PC12 cells. The active sample was separated by open columns, followed by HPLC purification to obtain active compound. Then, specific inhibitors were used to investigate signaling pathway of neurite outgrowth induced by the active compound. Finally, western blot analysis was performed to confirm the pathway proposed by inhibitor experiments. The ethyl acetate layer sample of extract of Lindernia crustacea exhibited significant neuritogenic activity. Two new compounds, named as linderside A and lindersin B, were isolated; their structures were elucidated by spectroscopic and chemical derivatization methods. Linderside A is a cucurbitane glycoside, whereas lindersin B is a cucurbitane triterpenoid. Each compound has an unusual isopentene unit, namely, a double bond bound to an unmodified isopropyl group at the end of cucurbitane triterpenoid side chain. Among them, lindersin B induced significant neurite outgrowth in PC12 cells, while linderside A was inactive against PC12 cells. Western blotting analysis results showed that lindersin B-induced neuritogenic activity depended on the activation of the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated

MTBP inhibits the Erk1/2-Elk-1 signaling in hepatocellular carcinoma

Science.gov (United States)

Ranjan, Atul; Iyer, Swathi V.; Ward, Christopher; Link, Tim; Diaz, Francisco J.; Dhar, Animesh; Tawfik, Ossama W.; Weinman, Steven A.; Azuma, Yoshiaki; Izumi, Tadahide; Iwakuma, Tomoo

2018-01-01

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, and the prognosis of HCC patients, especially those with metastasis, remains extremely poor. This is partly due to unclear molecular mechanisms underlying HCC metastasis. Our previous study indicates that MDM2 Binding Protein (MTBP) suppresses migration and metastasis of HCC cells. However, signaling pathways regulated by MTBP remain unknown. To identify metastasis-associated signaling pathways governed by MTBP, we have performed unbiased luciferase reporter-based signal array analyses and found that MTBP suppresses the activity of the ETS-domain transcription factor Elk-1, a downstream target of Erk1/2 MAP kinases. MTBP also inhibits phosphorylation of Elk-1 and decreases mRNA expression of Elk-1 target genes. Reduced Elk-1 activity is caused by inhibited nuclear translocation of phosphorylated Erk1/2 (p-Erk) by MTBP and subsequent inhibition of Elk-1 phosphorylation. We also reveal that MTBP inhibits the interaction of p-Erk with importin-7/RanBP7 (IPO7), an importin family member which shuttles p-Erk into the nucleus, by binding to IPO7. Moreover, high levels of MTBP in human HCC tissues are correlated with cytoplasmic localization of p-Erk1/2. Our study suggests that MTBP suppresses metastasis, at least partially, by down-modulating the Erk1/2-Elk-1 signaling pathway, thus identifying a novel regulatory mechanism of HCC metastasis by regulating the subcellular localization of p-Erk. PMID:29765550

Superior Long-Term Synaptic Memory Induced by Combining Dual Pharmacological Activation of PKA and ERK with an Enhanced Training Protocol

Science.gov (United States)

Liu, Rong-Yu; Neveu, Curtis; Smolen, Paul; Cleary, Leonard J.; Byrne, John H.

2017-01-01

Developing treatment strategies to enhance memory is an important goal of neuroscience research. Activation of multiple biochemical signaling cascades, such as the protein kinase A (PKA) and extracellular signal-regulated kinase (ERK) pathways, is necessary to induce long-term synaptic facilitation (LTF), a correlate of long-term memory (LTM).…

KSR1 is a functional protein kinase capable of serine autophosphorylation and direct phosphorylation of MEK1

International Nuclear Information System (INIS)

Goettel, Jeremy A.; Liang, Dongchun; Hilliard, Valda C.; Edelblum, Karen L.; Broadus, Matthew R.; Gould, Kathleen L.; Hanks, Steven K.; Polk, D. Brent

2011-01-01

The extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway is a highly conserved signaling pathway that regulates diverse cellular processes including differentiation, proliferation, and survival. Kinase suppressor of Ras-1 (KSR1) binds each of the three ERK cascade components to facilitate pathway activation. Even though KSR1 contains a C-terminal kinase domain, evidence supporting the catalytic function of KSR1 remains controversial. In this study, we produced recombinant wild-type or kinase-inactive (D683A/D700A) KSR1 proteins in Escherichia coli to test the hypothesis that KSR1 is a functional protein kinase. Recombinant wild-type KSR1, but not recombinant kinase-inactive KSR1, underwent autophosphorylation on serine residue(s), phosphorylated myelin basic protein (MBP) as a generic substrate, and phosphorylated recombinant kinase-inactive MAPK/ERK kinase-1 (MEK1). Furthermore, FLAG immunoprecipitates from KSR1 -/- colon epithelial cells stably expressing FLAG-tagged wild-type KSR1 (+KSR1), but not vector (+vector) or FLAG-tagged kinase-inactive KSR1 (+D683A/D700A), were able to phosphorylate kinase-inactive MEK1. Since TNF activates the ERK pathway in colon epithelial cells, we tested the biological effects of KSR1 in the survival response downstream of TNF. We found that +vector and +D683A/D700A cells underwent apoptosis when treated with TNF, whereas +KSR1 cells were resistant. However, +KSR1 cells were sensitized to TNF-induced cell loss in the absence of MEK kinase activity. These data provide clear evidence that KSR1 is a functional protein kinase, MEK1 is an in vitro substrate of KSR1, and the catalytic activities of both proteins are required for eliciting cell survival responses downstream of TNF.

Human p38δ MAP kinase mediates UV irradiation induced up-regulation of the gene expression of chemokine BRAK/CXCL14

International Nuclear Information System (INIS)

Ozawa, Shigeyuki; Ito, Shin; Kato, Yasumasa; Kubota, Eiro; Hata, Ryu-Ichiro

2010-01-01

The mitogen-activated protein kinase (MAPK) family comprises ERK, JNK, p38 and ERK5 (big-MAPK, BMK1). UV irradiation of squamous cell carcinoma cells induced up-regulation of gene expression of chemokine BRAK/CXCL14, stimulated p38 phosphorylation, and down-regulated the phosphorylation of ERK. Human p38 MAPKs exist in 4 isoforms: p38α, β, γ and δ. The UV stimulation of p38 phosphorylation was not inhibited by the presence of SB203580 or PD169316, inhibitors of p38α and β, suggesting p38 phosphorylation was not dependent on these 2 isoforms and that p38γ and/or δ was responsible for the phosphorylation. In fact, inhibition of each of these 4 p38 isoforms by the introduction of short hairpin (sh) RNAs for respective isoforms revealed that only shRNA for p38δ attenuated the UV-induced up-regulation of BRAK/CXCL14 gene expression. In addition, over-expression of p38 isoforms in the cells showed the association of p38δ with ERK1 and 2, concomitant with down-regulation of ERK phosphorylation. The usage of p38δ isoform by UV irradiation is not merely due to the abundance of this p38 isoform in the cells. Because serum deprivation of the cells also induced an increase in BRAK/CXCL14 gene expression, and in this case p38α and/or β isoform is responsible for up-regulation of BRAK/CXCL14 gene expression. Taken together, the data indicate that the respective stress-dependent action of p38 isoforms is responsible for the up-regulation of the gene expression of the chemokine BRAK/CXCL14.

ERK mutations confer resistance to mitogen-activated protein kinase pathway inhibitors.

Science.gov (United States)

Goetz, Eva M; Ghandi, Mahmoud; Treacy, Daniel J; Wagle, Nikhil; Garraway, Levi A

2014-12-01

The use of targeted therapeutics directed against BRAF(V600)-mutant metastatic melanoma improves progression-free survival in many patients; however, acquired drug resistance remains a major medical challenge. By far, the most common clinical resistance mechanism involves reactivation of the MAPK (RAF/MEK/ERK) pathway by a variety of mechanisms. Thus, targeting ERK itself has emerged as an attractive therapeutic concept, and several ERK inhibitors have entered clinical trials. We sought to preemptively determine mutations in ERK1/2 that confer resistance to either ERK inhibitors or combined RAF/MEK inhibition in BRAF(V600)-mutant melanoma. Using a random mutagenesis screen, we identified multiple point mutations in ERK1 (MAPK3) and ERK2 (MAPK1) that could confer resistance to ERK or RAF/MEK inhibitors. ERK inhibitor-resistant alleles were sensitive to RAF/MEK inhibitors and vice versa, suggesting that the future development of alternating RAF/MEK and ERK inhibitor regimens might help circumvent resistance to these agents. ©2014 American Association for Cancer Research.

BAG3 controls angiogenesis through regulation of ERK phosphorylation.

Science.gov (United States)

Falco, A; Festa, M; Basile, A; Rosati, A; Pascale, M; Florenzano, F; Nori, S L; Nicolin, V; Di Benedetto, M; Vecchione, M L; Arra, C; Barbieri, A; De Laurenzi, V; Turco, M C

2012-12-13

BAG3 is a co-chaperone of the heat shock protein (Hsp) 70, is expressed in many cell types upon cell stress, however, its expression is constitutive in many tumours. We and others have previously shown that in neoplastic cells BAG3 exerts an anti-apoptotic function thus favoring tumour progression. As a consequence we have proposed BAG3 as a target of antineoplastic therapies. Here we identify a novel role for BAG3 in regulation of neo-angiogenesis and show that its downregulation results in reduced angiogenesis therefore expanding the role of BAG3 as a therapeutical target. In brief we show that BAG3 is expressed in endothelial cells and is essential for the interaction between ERK and its phosphatase DUSP6, as a consequence its removal results in reduced binding of DUSP6 to ERK and sustained ERK phosphorylation that in turn determines increased levels of p21 and p15 and cell-cycle arrest in the G1 phase.

Aerobic exercise regulates blood lipid and insulin resistance via the toll‑like receptor 4‑mediated extracellular signal‑regulated kinases/AMP‑activated protein kinases signaling pathway.

Science.gov (United States)

Wang, Mei; Li, Sen; Wang, Fubaihui; Zou, Jinhui; Zhang, Yanfeng

2018-06-01

Diabetes mellitus is a complicated metabolic disease with symptoms of hyperglycemia, insulin resistance, chronic damage and dysfunction of tissues, and metabolic syndrome for insufficient insulin production. Evidence has indicated that exercise treatments are essential in the progression of type‑ІІ diabetes mellitus, and affect insulin resistance and activity of islet β‑cells. In the present study, the efficacy and signaling mechanism of aerobic exercise on blood lipids and insulin resistance were investigated in the progression of type‑ІІ diabetes mellitus. Body weight, glucose metabolism and insulin serum levels were investigated in mouse models of type‑ІІ diabetes mellitus following experienced aerobic exercise. Expression levels of inflammatory factors, interleukin (IL)‑6, high‑sensitivity C‑reactive protein, tumor necrosis factor‑α and leucocyte differentiation antigens, soluble CD40 ligand in the serum were analyzed in the experimental mice. In addition, expression levels of toll‑like receptor 4 (TLR‑4) were analyzed in the liver cells of experimental mice. Changes of oxidative stress indicators, including reactive oxygen species, superoxide dismutase, glutathione and catalase were examined in the liver cells of experimental mice treated by aerobic exercise. Expression levels and activity of extracellular signal‑regulated kinases (ERK) and AMP‑activated protein kinase (AMPK) signaling pathways were investigated in the liver cells of mouse models of type‑ІІ diabetes mellitus after undergoing aerobic exercise. Aerobic exercise decreased the expression levels of inflammatory factors in the serum of mouse models of type‑ІІ diabetes mellitus. The results indicated that aerobic exercise downregulated oxidative stress indicators in liver cells from mouse models of type‑ІІ diabetes mellitus. In addition, the ERK and AMPK signaling pathways were inactivated by aerobic exercise in liver cells in mouse models of type�

Crosstalk between G protein-coupled receptors (GPCRs and tyrosine kinase receptor (TXR in the heart after morphine withdrawal

Directory of Open Access Journals (Sweden)

Pilar eAlmela

2013-12-01

Full Text Available G protein-coupled receptors (GPCRs comprise a large family of membrane receptors involved in signal transduction. These receptors are linked to a variety of physiological and biological processes such as regulation of neurotransmission, growth and cell differentiation among others. Some of the effects of GPCRs are known to be mediated by the activation of mitogen-activated extracellular kinase (MAPK pathways. Cross-talk among various signal pathways plays an important role in activation of intracellular and intranuclear signal transduction cascades. Naloxone-induced morphine withdrawal leads to an up-regulation of adenyl cyclase-mediated signalling, resulting in high expression of protein kinase (PK A. In addition, there is also an increased expression of extracellular signal regulated kinase (ERK, one member of MAPK. For this reason, the crosstalk between these GPCRs and receptors with tyrosine kinase activity (TKR can be considered a possible mechanism for adaptive changes that occurs after morphine withdrawal. Morphine withdrawal activates ERK1/2 and phosphorylated tyrosine hydroxylase (TH at Ser31 in the right and left ventricle. When N-(2-guanidinoethyl-5-isoquinolinesulfonamide (HA-1004, a PKA inhibitor was infused, the ability of morphine withdrawal to activate ERK, which phosphorylates TH at Ser31, was reduced. The present finding demonstrated that the enhancement of ERK1/2 expression and the phosphorylation state of TH at Ser31 during morphine withdrawal are dependent on PKA and suggest cross-talk between PKA and ERK1/2 transduction pathway mediating morphine withdrawal-induced activation of TH. Increasing understanding of the mechanisms that interconnect the two pathway regulated by GPCRs and TKRs may facilitate the design of new therapeutic strategies.

Contractions activate hormone-sensitive lipase in rat muscle by protein kinase C and mitogen-activated protein kinase

DEFF Research Database (Denmark)

Donsmark, Morten; Langfort, Jozef; Holm, Cecilia

2003-01-01

and contractions. Adrenaline acts via cAMP-dependent protein kinase (PKA). The signalling mediating the effect of contractions is unknown and was explored in this study. Incubated soleus muscles from 70 g male rats were electrically stimulated to perform repeated tetanic contractions for 5 min. The contraction......Intramuscular triacylglycerol is an important energy store and is also related to insulin resistance. The mobilization of fatty acids from this pool is probably regulated by hormone-sensitive lipase (HSL), which has recently been shown to exist in muscle and to be activated by both adrenaline......-induced activation of HSL was abolished by the protein kinase C (PKC) inhibitors bisindolylmaleimide I and calphostin C and reduced 50% by the mitogen-activated protein kinase kinase (MEK) inhibitor U0126, which also completely blocked extracellular signal-regulated kinase (ERK) 1 and 2 phosphorylation. None...

Effects of chronic sleep deprivation on the extracellular signal-regulated kinase pathway in the temporomandibular joint of rats.

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Chuan Ma

Full Text Available OBJECTIVES: To examine the possible involvement and regulatory mechanisms of extracellular signal-regulated kinase (ERK pathway in the temporomandibular joint (TMJ of rats subjected to chronic sleep deprivation (CSD. METHODS: Rats were subjected to CSD using the modified multiple platform method (MMPM. The serum levels of corticosterone (CORT and adrenocorticotropic hormone (ACTH were tested and histomorphology and ultrastructure of the TMJ were observed. The ERK and phospho-ERK (p-ERK expression levels were detected by Western blot analysis, and the MMP-1, MMP-3, and MMP-13 expression levels were detected by real-time quantitative polymerase chain reaction (PCR and Western blotting. RESULTS: The elevated serum CORT and ACTH levels confirmed that the rats were under CSD stress. Hematoxylin and eosin (HE staining and scanning electron microscopy (SEM showed pathological alterations in the TMJ following CSD; furthermore, the p-ERK was activated and the mRNA and protein expression levels of MMP-1, MMP-3, and MMP-13 were upregulated after CSD. In the rats administered with the selective ERK inhibitor U0126, decreased tissue destruction was observed. Phospho-ERK activation was visibly blocked and the MMP-1, MMP-3, and MMP-13 mRNA and protein levels were lower than the corresponding levels in the CSD without U0126 group. CONCLUSION: These findings indicate that CSD activates the ERK pathway and upregulates the MMP-1, MMP-3, and MMP-13 mRNA and protein levels in the TMJ of rats. Thus, CSD induces ERK pathway activation and causes pathological alterations in the TMJ. ERK may be associated with TMJ destruction by promoting the expression of MMPs.

Nitrosative/oxidative stress conditions regulate thioredoxin-interacting protein (TXNIP) expression and thioredoxin-1 (TRX-1) nuclear localization.

Science.gov (United States)

Ogata, Fernando Toshio; Batista, Wagner Luiz; Sartori, Adriano; Gesteira, Tarsis Ferreira; Masutani, Hiroshi; Arai, Roberto Jun; Yodoi, Junji; Stern, Arnold; Monteiro, Hugo Pequeno

2013-01-01

Thioredoxin (TRX-1) is a multifunctional protein that controls the redox status of other proteins. TRX-1 can be found in the extracellular milieu, cytoplasm and nucleus, and it has distinct functions in each environment. Previously, we studied the intracellular localization of TRX-1 and its relationship with the activation of the p21Ras-ERK1/2 MAP Kinases signaling pathway. In situations where this pathway was activated by stress conditions evoked by a nitrosothiol, S-nitroso-N-acetylpenicillamine (SNAP), TRX-1 accumulated in the nuclear compartment due to nitrosylation of p21Ras and activation of downstream ERK1/2 MAP kinases. Presently, we demonstrate that ERK1/2 MAP Kinases activation and spatial distribution within cells trigger TRX-1 nuclear translocation through down-regulation of the physiological inhibitor of TRX-1, Thioredoxin Interacting Protein (TXNIP). Once activated by the oxidants, SNAP and H₂O₂, the ERK1/2 MAP kinases migrate to the nucleus. This is correlated with down-regulation of TXNIP. In the presence of the MEK inhibitors (PD98059 or UO126), or in cells transfected with the Protein Enriched in Astrocytes (PEA-15), a cytoplasmic anchor of ERK1/2 MAP kinases, TRX-1 nuclear migration and TXNIP down-regulation are no longer observed in cells exposed to oxidants. On the other hand, over-expression of TXNIP abolishes nuclear migration of TRX-1 under nitrosative/oxidative stress conditions, whereas gene silencing of TXNIP facilitates nuclear migration even in the absence of stress conditions. Studies based on the TXNIP promoter support this regulation. In conclusion, changes in TRX-1 compartmentalization under nitrosative/oxidative stress conditions are dependent on the expression levels of TXNIP, which are regulated by cellular compartmentalization and activation of the ERK1/2 MAP kinases.

Nitrosative/oxidative stress conditions regulate thioredoxin-interacting protein (TXNIP expression and thioredoxin-1 (TRX-1 nuclear localization.

Directory of Open Access Journals (Sweden)

Fernando Toshio Ogata

Full Text Available Thioredoxin (TRX-1 is a multifunctional protein that controls the redox status of other proteins. TRX-1 can be found in the extracellular milieu, cytoplasm and nucleus, and it has distinct functions in each environment. Previously, we studied the intracellular localization of TRX-1 and its relationship with the activation of the p21Ras-ERK1/2 MAP Kinases signaling pathway. In situations where this pathway was activated by stress conditions evoked by a nitrosothiol, S-nitroso-N-acetylpenicillamine (SNAP, TRX-1 accumulated in the nuclear compartment due to nitrosylation of p21Ras and activation of downstream ERK1/2 MAP kinases. Presently, we demonstrate that ERK1/2 MAP Kinases activation and spatial distribution within cells trigger TRX-1 nuclear translocation through down-regulation of the physiological inhibitor of TRX-1, Thioredoxin Interacting Protein (TXNIP. Once activated by the oxidants, SNAP and H₂O₂, the ERK1/2 MAP kinases migrate to the nucleus. This is correlated with down-regulation of TXNIP. In the presence of the MEK inhibitors (PD98059 or UO126, or in cells transfected with the Protein Enriched in Astrocytes (PEA-15, a cytoplasmic anchor of ERK1/2 MAP kinases, TRX-1 nuclear migration and TXNIP down-regulation are no longer observed in cells exposed to oxidants. On the other hand, over-expression of TXNIP abolishes nuclear migration of TRX-1 under nitrosative/oxidative stress conditions, whereas gene silencing of TXNIP facilitates nuclear migration even in the absence of stress conditions. Studies based on the TXNIP promoter support this regulation. In conclusion, changes in TRX-1 compartmentalization under nitrosative/oxidative stress conditions are dependent on the expression levels of TXNIP, which are regulated by cellular compartmentalization and activation of the ERK1/2 MAP kinases.

c-Jun controls the efficiency of MAP kinase signaling by transcriptional repression of MAP kinase phosphatases

International Nuclear Information System (INIS)

Sprowles, Amy; Robinson, Dan; Wu Yimi; Kung, H.-J.; Wisdom, Ron

2005-01-01

The mammalian JNK signaling pathway regulates the transcriptional response of cells to environmental stress, including UV irradiation. This signaling pathway is composed of a classical MAP kinase cascade; activation results in phosphorylation of the transcription factor substrates c-Jun and ATF2, and leads to changes in gene expression. The defining components of this pathway are conserved in the fission yeast S. pombe, where the genetic studies have shown that the ability of the JNK homolog Spc1 to be activated in response to UV irradiation is dependent on the presence of the transcription factor substrate Atf1. We have used genetic analysis to define the role of c-Jun in activation of the mammalian JNK signaling pathway. Our results show that optimal activation of JNK requires the presence of its transcription factor substrate c-Jun. Mutational analysis shows that the ability of c-Jun to support efficient activation of JNK requires the ability of Jun to bind DNA, suggesting a transcriptional mechanism. Consistent with this, we show that c-Jun represses the expression of several MAP kinase phosphatases. In the absence of c-Jun, the increased expression of MAP kinase phosphatases leads to impaired activation of the ERK, JNK, and p38 MAP kinases after pathway activation. The results show that one function of c-Jun is to regulate the efficiency of signaling by the ERK, p38, and JNK MAP kinases, a function that is likely to affect cellular responses to many different stimuli

Extracellular Signal-Regulated Kinase 2 (ERK2) Phosphorylation Sites and Docking Domain on the Nuclear Pore Complex Protein Tpr Cooperatively Regulate ERK2-Tpr Interaction

Czech Academy of Sciences Publication Activity Database

Vomastek, Tomáš; Iwanicky, M. P.; Burack, W. R.; Tiwari, D.; Kumar, D.; Parsons, J. T.; Weber, M. J.; Nandicoori, V. K.

2008-01-01

Roč. 28, č. 22 (2008), s. 6954-6966 ISSN 0270-7306 R&D Projects: GA AV ČR IAA500200716 Institutional research plan: CEZ:AV0Z50200510 Keywords : erk * docking domain * cell growth Subject RIV: EE - Microbiology, Virology Impact factor: 5.942, year: 2008

Naringenin modulates the metastasis of human prostate cancer cells by down regulating the matrix metalloproteinases -2/-9 via ROS/ERK1/2 pathways

Directory of Open Access Journals (Sweden)

Er-Jiang Lin

2014-08-01

Full Text Available Metastasis is a multifactorial condition that complicates cancer treatment options and widens the target of treatment. Matrix mettalopriteinases (MMPs of the extracellular matrix (ECM are involved in metastasis, thus they present as potential targets in halting cancer metastasis. The study was undertaken to investigate the influence of naringenin, a naturally occurring flavonoid on the metastasis of human prostate cancer cells (PC-3 and DU145. Naringenin was observed to be effective in reducing the viability and migratory percentage of PC-3 and DU145 cells. Naringenin significantly reduced the expression and activities of the chief MMPs (MMP-2 and MMP-9 as assessed by western blotting, real-time PCR and gelatin zymography analysis. The influence of naringenin on extracellular signal-regulated kinase (ERK -ERK1/2 was analysed by western blotting. The results indicated that naringenin was able to effectively inhibit ERK1/2. Naringenin exposure also significantly suppressed the levels of reactive oxygen species (ROS. Naringenin thus stands as an effective chemotherapeutic agent for prostate cancer treatment that could be further explored.

Induction of apoptosis in renal cell carcinoma by reactive oxygen species: involvement of extracellular signal-regulated kinase 1/2, p38delta/gamma, cyclooxygenase-2 down-regulation, and translocation of apoptosis-inducing factor.

LENUS (Irish Health Repository)

Ambrose, Monica

2012-02-03

Renal cell carcinoma (RCC) is the most common malignancy of the kidney. Unfortunately, RCCs are highly refractory to conventional chemotherapy, radiation therapy, and even immunotherapy. Thus, novel therapeutic targets need to be sought for the successful treatment of RCCs. We now report that 6-anilino-5,8-quinolinequinone (LY83583), an inhibitor of cyclic GMP production, induced growth arrest and apoptosis of the RCC cell line 786-0. It did not prove deleterious to normal renal epithelial cells, an important aspect of chemotherapy. To address the cellular mechanism(s), we used both genetic and pharmacological approaches. LY83583 induced a time- and dose-dependent increase in RCC apoptosis through dephosphorylation of mitogen-activated protein kinase kinase 1\\/2 and its downstream extracellular signal-regulated kinases (ERK) 1 and -2. In addition, we observed a decrease in Elk-1 phosphorylation and cyclooxygenase-2 (COX-2) down-regulation. We were surprised that we failed to observe an increase in either c-Jun NH(2)-terminal kinase or p38alpha and -beta mitogen-activated protein kinase activation. In contradiction, reintroduction of p38delta by stable transfection or overexpression of p38gamma dominant negative abrogated the apoptotic effect. Cell death was associated with a decrease and increase in Bcl-x(L) and Bax expression, respectively, as well as release of cytochrome c and translocation of apoptosis-inducing factor. These events were associated with an increase in reactive oxygen species formation. The antioxidant N-acetyl l-cysteine, however, opposed LY83583-mediated mitochondrial dysfunction, ERK1\\/2 inactivation, COX-2 down-regulation, and apoptosis. In conclusion, our results suggest that LY83583 may represent a novel therapeutic agent for the treatment of RCC, which remains highly refractory to antineoplastic agents. Our data provide a molecular basis for the anticancer activity of LY83583.

Hesperidin, A Popular Antioxidant Inhibits Melanogenesis via Erk1/2 Mediated MITF Degradation

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Heun Joo Lee

2015-08-01

Full Text Available Regulation of melanogenesis has been the focus of treatment for hyperpigmentary skin disorders. Although hesperidin is one of the most well-known, naturally occurring flavonoids with antioxidant and anti-inflammatory effect, its anti-melanogenic effect is not known. The present study aims to determine the anti-melanogenic effect of hespiridin as well as its underlying molecular mechanisms. Melanin contents were measured in normal human melanocytes and B16F10 melanoma cells. Protein and mRNA levels of tyrosinase, microphthalmia-associated transcription factor (MITF, tyrosinase related protein-1 (TRP-1 and TRP-2 were determined. Melanogenesis-regulating signals were examined. In results, hesperidin strongly inhibited melanin synthesis and tyrosinase activity. Hesperidin decreased tyrosinase, TRP-1, and TRP-2 protein expression but increased phospho-extracellular signal-regulated kinase 1/2 (p-Erk1/2 expression. Specific inhibitor of Erk1/2 or proteasome inhibitor reversed the inhibition of melanogenesis induced by hesperidin. Taken together, hesperidin, a popular antioxidant, stimulated Erk1/2 phosphorylation which subsequently degraded MITF which resulted in suppression of melanogenic enzymes and melanin synthesis.

Unc-51 controls active zone density and protein composition by downregulating ERK signaling.

Science.gov (United States)

Wairkar, Yogesh P; Toda, Hirofumi; Mochizuki, Hiroaki; Furukubo-Tokunaga, Katsuo; Tomoda, Toshifumi; Diantonio, Aaron

2009-01-14

Efficient synaptic transmission requires the apposition of neurotransmitter release sites opposite clusters of postsynaptic neurotransmitter receptors. Transmitter is released at active zones, which are composed of a large complex of proteins necessary for synaptic development and function. Many active zone proteins have been identified, but little is known of the mechanisms that ensure that each active zone receives the proper complement of proteins. Here we use a genetic analysis in Drosophila to demonstrate that the serine threonine kinase Unc-51 acts in the presynaptic motoneuron to regulate the localization of the active zone protein Bruchpilot opposite to glutamate receptors at each synapse. In the absence of Unc-51, many glutamate receptor clusters are unapposed to Bruchpilot, and ultrastructural analysis demonstrates that fewer active zones contain dense body T-bars. In addition to the presence of these aberrant synapses, there is also a decrease in the density of all synapses. This decrease in synaptic density and abnormal active zone composition is associated with impaired evoked transmitter release. Mechanistically, Unc-51 inhibits the activity of the MAP kinase ERK to promote synaptic development. In the unc-51 mutant, increased ERK activity leads to the decrease in synaptic density and the absence of Bruchpilot from many synapses. Hence, activated ERK negatively regulates synapse formation, resulting in either the absence of active zones or the formation of active zones without their proper complement of proteins. The Unc-51-dependent inhibition of ERK activity provides a potential mechanism for synapse-specific control of active zone protein composition and release probability.

Stress and vascular responses: atheroprotective effect of laminar fluid shear stress in endothelial cells: possible role of mitogen-activated protein kinases.

Science.gov (United States)

Yoshizumi, Masanori; Abe, Jun-Ichi; Tsuchiya, Koichiro; Berk, Bradford C; Tamaki, Toshiaki

2003-03-01

Atherosclerosis preferentially occurs in areas of turbulent blood flow and low fluid shear stress, whereas laminar blood flow and high shear stress are atheroprotective. Inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha), stimulate expression of endothelial cell (EC) genes that may promote atherosclerosis. Recent findings suggest a steady laminar blood flow decreases EC apoptosis and inhibits TNF-mediated EC activation. EC apoptosis or activation is suggested to be involved in plaque erosion, which may lead to platelet aggregation. TNF-alpha regulates gene expression in ECs, in part, by stimulating mitogen-activated protein (MAP) kinases, which phosphorylate transcription factors. We hypothesized that steady laminar flow inhibits cytokine-mediated activation of MAP kinases in ECs. To test this hypothesis, we determined the effects of steady laminar flow (shear stress = 12 dynes/cm(2)) on TNF-alpha-stimulated activity of three MAP kinases in human umbilical vein ECs (HUVEC): extracellular signal-regulated kinase (ERK1/2), c-Jun N-terminal kinase (JNK), and p38. TNF-alpha activated ERK1/2, JNK, and p38 maximally at 15 min in HUVEC. Pre-exposing HUVEC for 10 min to flow inhibited TNF-alpha activation of JNK, but showed no significant effect on ERK1/2 or p38 activation. Incubation of HUVEC with PD98059, a specific ERK1/2 inhibitor, blocked the flow-mediated inhibition of TNF activation of JNK. Transfection studies with dominant-negative constructs of the protein kinase MEK5 suggested an important role for big mitogen-activated protein kinase 1 (BMK1) in flow-mediated regulation of EC activation by TNF-alpha. Understanding the mechanisms by which steady laminar flow regulates JNK activation by cytokines may provide insight into the atheroprotective mechanisms induced by laminar blood flow.

Shengui Sansheng San extraction is an angiogenic switch via regulations of AKT/mTOR, ERK1/2 and Notch1 signal pathways after ischemic stroke.

Science.gov (United States)

Liu, Bowen; Luo, Cheng; Zheng, Zhaoguang; Xia, Zhenyan; Zhang, Qian; Ke, Chienchih; Liu, Renshyan; Zhao, Yonghua

2018-05-15

As a traditional Chinese herbal formula, Shengui Sansheng San (SSS) has been employed for stroke treatment more than 300 years. We hypothesize that SSS extraction is an angiogenic switch in penumbra post-stroke, and corresponding mechanisms are investigated. In present study, rats were subjected to permanent middle cerebral artery occlusion model (MCAo) and were treated with low, middle and high doses of SSS extraction. We assessed neurological function and survival rate, and measured infarct volume by 2,3,5-triphenyltetrazolium chloride staining on day 7 after ischemia. von Willebrand factor (vWF), stromal cell-derived factor-1 alpha (SDF-1α) /chemokine (C-X-C motif) receptor 4 (CXCR4) axis, vascular endothelial growth factor (VEGF)/VEGF receptor 2 (VEGFR2) as well as protein kinase B (AKT)/mammalian target of rapamycin (mTOR) /hypoxia-inducible factor-1 alpha (HIF-1α), extracellular signal-regulated kinase 1/2 (ERK1/2) and Notch1 signaling pathways were respectively investigated by immunofluorescence assay or western blotting in vivo and oxygen-glucose-deprived (OGD) brain microvascular endothelial cells (BMECs); simultaneously, wound healing of BMECs and tube formation assay were administrated. Compared to MCAo group, SSS extraction could significantly improve neurological functional scores, survival rate and cerebral infarct volume, enhance vWF + vascular density and perimeter, SDF-1α/CXCR4 axis, VEGF expression, as well as activate AKT/mTOR/HIF-1α and ERK1/2 and inhibit Notch1 pathways in penumbra. In vitro, containing SSS extraction serum increased BMEC migration, capillary formation and VEGF expression via up-regulations of AKT/mTOR and ERK1/2 pathways in OGD BMECs, but ERK inhibitor (U0126) reversed the result of VEGF expression in high dose of SSS group. Additionally, VEGFR2 and Notch1 expressions were suppressed by containing SSS extraction serum. All results were in dose dependent manner. Our study firstly demonstrates that SSS extraction is an

Cyanidin-3-O-galactoside and blueberry extracts supplementation improves spatial memory and regulates hippocampal ERK expression in senescence-accelerated mice.

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Tan, Long; Yang, Hong Peng; Pang, Wei; Lu, Hao; Hu, Yan Dan; Li, Jing; Lu, Shi Jun; Zhang, Wan Qi; Jiang, Yu Gang

2014-03-01

To investigate whether the antioxidation and the regulation on the Extracellular Regulated Protein Kinases (ERK) signaling pathway are involved in the protective effects of blueberry on central nervous system. 30 Senescence-accelerated mice prone 8 (SAMP8) mice were divided into three groups and treated with normal diet, blueberry extracts (200 mg/kg•bw/day) and cyaniding-3-O-galactoside (Cy-3-GAL) (50 mg/kg•bw/day) from blueberry for 8 weeks. 10 SAMR1 mice were set as control group. The capacity of spatial memory was assessed by Passive avoidance task and Morris water maze. Histological analyses on hippocampus were completed. Malondialdehyde (MDA) levels, Superoxide Dismutase (SOD) activity and the expression of ERK were detected. Both Cy-3-GAL and blueberry extracts were shown effective functions to relieve cellular injury, improve hippocampal neurons survival and inhibit the pyramidal cell layer damage. Cy-3-GAL and blueberry extracts also increased SOD activity and reduced MDA content in brain tissues and plasma, and increased hippocampal phosphorylated ERK (p-ERK) expression in SAMP8 mice. Further more, the passive avoidance task test showed that both the latency time and the number of errors were improved by Cy-3-GAL treatment, and the Morris Water Maze test showed significant decreases of latency were detected by Cy-3-GAL and blueberry extracts treatment on day 4. Blueberry extracts may reverse the declines of cognitive and behavioral function in the ageing process through several pathways, including enhancing the capacity of antioxidation, altering stress signaling. Cy-3-GAL may be an important active ingredient for these biological effects. Copyright © 2014 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

Signaling pathways of interleukin-1 actions in the brain: anatomical distribution of phospho-ERK1/2 in the brain of rat treated systemically with interleukin-1beta.

Science.gov (United States)

Nadjar, A; Combe, C; Busquet, P; Dantzer, R; Parnet, P

2005-01-01

Interleukin-1beta is released at the periphery during infection and acts on the nervous system to induce fever, neuroendocrine activation, and behavioral changes. These effects are mediated by brain type I IL-1 receptors. In vitro studies have shown the ability of interleukin-1beta to activate mitogen-activated protein kinase signaling pathways including p38, c-Jun N-terminal kinase and extracellular signal-regulated protein kinase 1 and 2 (ERK1/2). In contrast to other mitogen-activated protein kinases, little is known about ERK1/2 activation in the rat brain in response to interleukin-1beta. The aim of the present study was therefore to investigate spatial and temporal activation of ERK1/2 in the rat brain after peripheral administration of interleukin-1beta using immunohistochemistry to detect the phosphorylated form of the kinase. In non-stimulated conditions, phosphorylated ERK1/2 immunoreactivity was observed in neurons throughout the brain. Administration of interleukin-1beta (60 microg/kg, i.p.) induced the phosphorylation of ERK1/2 in areas at the interface between brain and blood or cerebrospinal fluid: meninges, circumventricular organs, endothelial like cells of the blood vessels, and in brain nuclei involved in behavioral depression, fever and neuroendocrine activation: paraventricular nucleus of the hypothalamus, supraoptic nucleus, central amygdala and arcuate nucleus. Double labeling of phosphorylated ERK1/2 and cell markers revealed the expression of phosphorylated ERK1/2 in neurons, astrocytes and microglia. Since phosphorylated ERK1/2 was found in structures in which type I IL-1 receptor has already been identified as well as in structures lacking this receptor, activation of ERK1/2 is likely to occur in response to both direct and indirect action of interleukin-1beta on its target cells.

ERK1/2 signalling pathway is involved in CD147-mediated gastric cancer cell line SGC7901 proliferation and invasion.

Science.gov (United States)

Chen, Liping; Pan, Yuqin; Gu, Ling; Nie, Zhenlin; He, Bangshun; Song, Guoqi; Li, Rui; Xu, Yeqiong; Gao, Tianyi; Wang, Shukui

2013-08-01

This study aimed to investigate the role of CD147 in the progression of gastric cancer and the signalling pathway involved in CD147-mediated gastric cancer cell line SGC7901 proliferation and invasion. Short hairpin RNA (shRNA) expression vectors targeting CD147 were constructed to silence CD147, and the expression of CD147 was monitored by quantitative realtime reverse transcriptase polymerase chain reaction and Western blot and further confirmed by immunohistochemistry in vivo. Cell proliferation was determined by Cell Counting Kit-8 assay, the activities of matrix metalloproteinase (MMP)-2 and MMP-9 were determined by gelatin zymography, and the invasion of SGC7901 was determined by invasion assay. The phosphorylation and non-phosphorylation of the mitogen-activated protein kinases, extracellular signal-regulated kinase1/2 (ERK1/2), P38 and c-Jun NH2-terminal kinase were examined by Western blot. Additionally, the ERK1/2 inhibitor U0126 were used to confirm the signalling pathway involved in CD147-mediated SGC7901 progression. The BALB/c nude mice were used to study tumour progression in vivo. The results revealed that CD147 silencing inhibited the proliferation and invasion of SGC7901 cells, and down-regulated the activities of MMP-2 and MMP-9 and the phosphorylation of the ERK1/2 in SGC7901 cells. ERK1/2 inhibitor U0126 decreased the proliferation, and invasion of SGC7901 cells, and down-regulated the MMP-2 and MMP-9 activities. In a nude mouse model of subcutaneous xenografts, the tumour volume was significantly smaller in the SGC7901/shRNA group compared to the SGC7901 and SGC7901/snc-RNA group. Immunohistochemistry analysis showed that CD147 and p-ERK1/2 protein expressions were down-regulated in the SGC7901/shRNA2 group compared to the SGC7901 and SGC7901/snc-RNA group. These results suggest that ERK1/2 pathway involves in CD147-mediated gastric cancer growth and invasion. These findings further highlight the importance of CD147 in cancer progression

Comparative Molecular Dynamics Simulations of Mitogen-Activated Protein Kinase-Activated Protein Kinase 5

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Inger Lindin

2014-03-01

Full Text Available The mitogen-activated protein kinase-activated protein kinase MK5 is a substrate of the mitogen-activated protein kinases p38, ERK3 and ERK4. Cell culture and animal studies have demonstrated that MK5 is involved in tumour suppression and promotion, embryogenesis, anxiety, cell motility and cell cycle regulation. In the present study, homology models of MK5 were used for molecular dynamics (MD simulations of: (1 MK5 alone; (2 MK5 in complex with an inhibitor; and (3 MK5 in complex with the interaction partner p38α. The calculations showed that the inhibitor occupied the active site and disrupted the intramolecular network of amino acids. However, intramolecular interactions consistent with an inactive protein kinase fold were not formed. MD with p38α showed that not only the p38 docking region, but also amino acids in the activation segment, αH helix, P-loop, regulatory phosphorylation region and the C-terminal of MK5 may be involved in forming a very stable MK5-p38α complex, and that p38α binding decreases the residual fluctuation of the MK5 model. Electrostatic Potential Surface (EPS calculations of MK5 and p38α showed that electrostatic interactions are important for recognition and binding.

Differential regulation of cystic fibrosis transmembrane conductance regulator and Na+,K+ -ATPase in gills of striped bass, Morone saxatilis: effect of salinity and hormones

DEFF Research Database (Denmark)

Madsen, Steffen; Jensen, Lars Nørholm; Tipsmark, Christian Kølbaek

2007-01-01

-regulated kinase (ERK) 1/2 was stimulated by EGF but not affected by IGF-I. This study is the first to report a branchial EGF response and to demonstrate a functional ERK 1/2 pathway in the teleost gill. In conclusion, CFTR and Na(+),K(+) -ATPase are differentially regulated by salinity and hormones in gills...

Dual-specificity phosphatase 6 (Dusp6), a negative regulator of FGF2/ERK1/2 signaling, enhances 17β-estradiol-induced cell growth in endometrial adenocarcinoma cell.

Science.gov (United States)

Zhang, Hui; Guo, Qiufen; Wang, Chong; Yan, Lei; Fu, Yibing; Fan, Mingjun; Zhao, Xingbo; Li, Mingjiang

2013-08-25

Dual-specificity phosphatase 6 (Dusp6) is a negative feedback mechanism of fibroblast growth factors (FGFs)/mitogen-activated protein kinase (MAPK)/ERK1/2 signaling. The aim of this study was to explore the expression of Dusp6 in human endometrial adenocarcinomas and the role of Dusp6 expression in the growth regulation of endometrial adenocarcinoma cell. We found that Dusp6 was over-expressed in human endometrial adenocarcinomas. In Ishikawa cells, plasmid-driven Dusp6 expression efficiently blocked the activity of FGF2-induced MAPK/ERK1/2 signaling. Unexpectedly, Dusp6 expression significantly enhanced the growth of Ishikawa cells. In Dusp6 forced-expression cells, 17β-estradiol stimulation increased the cell growth by all most threefolds. In addition, progesterone treatment reduced the cell growth to about half both in Ishikawa cells with and without forced-Dusp6-expression. Dusp6 over-expression is involved in the pathogenesis and development of human endometrial adenocarcinomas. Dusp6 functions as a negative regulator of FGF2/ERK1/2 signaling but enhances the growth and 17β-estradiol-induced cell growth in endometrial adenocarcinoma cell. Copyright © 2013. Published by Elsevier Ireland Ltd.

Terbinafine stimulates the pro-inflammatory responses in human monocytic THP-1 cells through an ERK signaling pathway.

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Mizuno, Katsuhiko; Fukami, Tatsuki; Toyoda, Yasuyuki; Nakajima, Miki; Yokoi, Tsuyoshi

2010-10-23

Oral antifungal terbinafine has been reported to cause liver injury with inflammatory responses in a small percentage of patients. However the underlying mechanism remains unknown. To examine the inflammatory reactions, we investigated whether terbinafine and other antifungal drugs increase the release of pro-inflammatory cytokines using human monocytic cells. Dose- and time-dependent changes in the mRNA expression levels and the release of interleukin (IL)-8 and tumor necrosis factor (TNF)α from human monocytic THP-1 and HL-60 cells with antifungal drugs were measured. Effects of terbinafine on the phosphorylation of extracellular signal-regulated kinase (ERK)1/2, p38 mitogen-activated protein (MAP) kinase and c-Jun N-terminal kinase (JNK)1/2 were investigated. The release of IL-8 and TNFα from THP-1 and HL-60 cells was significantly increased by treatment with terbinafine but not by fluconazole, suggesting that terbinafine can stimulate monocytes and increase the pro-inflammatory cytokine release. Terbinafine also significantly increased the phosphorylation of ERK1/2 and p38 MAP kinase in THP-1 cells. Pretreatment with a MAP kinase/ERK kinase (MEK)1/2 inhibitor U0126 significantly suppressed the increase of IL-8 and TNFα levels by terbinafine treatment in THP-1 cells, but p38 MAPK inhibitor SB203580 did not. These results suggested that an ERK1/2 pathway plays an important role in the release of IL-8 and TNFα in THP-1 cells treated with terbinafine. The release of inflammatory mediators by terbinafine might be one of the mechanisms underlying immune-mediated liver injury. This in vitro method may be useful to predict adverse inflammatory reactions that lead to drug-induced liver injury. Copyright © 2010 Elsevier Inc. All rights reserved.

Eight paths of ERK1/2 signalling pathway regulating hepatocyte ...

Indian Academy of Sciences (India)

2011-12-05

Dec 5, 2011 ... This study aims at exploring which paths of ERK1/2 signalling pathway participate in the regulation of rat .... total RNA was used to synthesize the first strand of cDNA. ..... stem cells contribute to regeneration of injured liver.

Proteomic Analysis Reveals a Role for Bcl2-associated Athanogene 3 and Major Vault Protein in Resistance to Apoptosis in Senescent Cells by Regulating ERK1/2 Activation*

Science.gov (United States)

Pasillas, Martina P.; Shields, Sarah; Reilly, Rebecca; Strnadel, Jan; Behl, Christian; Park, Robin; Yates, John R.; Klemke, Richard; Gonias, Steven L.; Coppinger, Judith A.

2015-01-01

Senescence is a prominent solid tumor response to therapy in which cells avoid apoptosis and instead enter into prolonged cell cycle arrest. We applied a quantitative proteomics screen to identify signals that lead to therapy-induced senescence and discovered that Bcl2-associated athanogene 3 (Bag3) is up-regulated after adriamycin treatment in MCF7 cells. Bag3 is a member of the BAG family of co-chaperones that interacts with Hsp70. Bag3 also regulates major cell-signaling pathways. Mass spectrometry analysis of the Bag3 Complex revealed a novel interaction between Bag3 and Major Vault Protein (MVP). Silencing of Bag3 or MVP shifts the cellular response to adriamycin to favor apoptosis. We demonstrate that Bag3 and MVP contribute to apoptosis resistance in therapy-induced senescence by increasing the level of activation of extracellular signal-regulated kinase1/2 (ERK1/2). Silencing of either Bag3 or MVP decreased ERK1/2 activation and promoted apoptosis in adriamycin-treated cells. An increase in nuclear accumulation of MVP is observed during therapy-induced senescence and the shift in MVP subcellular localization is Bag3-dependent. We propose a model in which Bag3 binds to MVP and facilitates MVP accumulation in the nucleus, which sustains ERK1/2 activation. We confirmed that silencing of Bag3 or MVP shifts the response toward apoptosis and regulates ERK1/2 activation in a panel of diverse breast cancer cell lines. This study highlights Bag3-MVP as an important complex that regulates a potent prosurvival signaling pathway and contributes to chemotherapy resistance in breast cancer. PMID:24997994

Gravity loading induces adenosine triphosphate release and phosphorylation of extracellular signal-regulated kinases in human periodontal ligament cells.

Science.gov (United States)

Ito, Mai; Arakawa, Toshiya; Okayama, Miki; Shitara, Akiko; Mizoguchi, Itaru; Takuma, Taishin

2014-11-01

The periodontal ligament (PDL) receives mechanical stress (MS) from dental occlusion or orthodontic tooth movement. Mechanical stress is thought to be a trigger for remodeling of the PDL and alveolar bone, although its signaling mechanism is still unclear. So we investigated the effect of MS on adenosine triphosphate (ATP) release and extracellular signal-regulated kinases (ERK) phosphorylation in PDL cells. Mechanical stress was applied to human PDL cells as centrifugation-mediated gravity loading. Apyrase, Ca(2+)-free medium and purinergic receptor agonists and antagonists were utilized to analyze the contribution of purinergic receptors to ERK phosphorylation. Gravity loading and ATP increased ERK phosphorylation by 5 and 2.5 times, respectively. Gravity loading induced ATP release from PDL cells by tenfold. Apyrase and suramin diminished ERK phosphorylation induced by both gravity loading and ATP. Under Ca(2+)-free conditions the phosphorylation by gravity loading was partially decreased, whereas ATP-induced phosphorylation was unaffected. Receptors P2Y4 and P2Y6 were prominently expressed in the PDL cells. Gravity loading induced ATP release and ERK phosphorylation in PDL fibroblasts, and ATP signaling via P2Y receptors was partially involved in this phosphorylation, which in turn would enhance gene expression for the remodeling of PDL tissue during orthodontic tooth movement. © 2013 Wiley Publishing Asia Pty Ltd.

The expression of ER, PR in endometrial cancer and analysis of their correlation with ERK signaling pathway.

Science.gov (United States)

Luo, Lan; Xu, Lina; Tang, Liang

2017-12-12

Endometrial carcinoma (EC) is a common malignant tumor in gynecology. Its incidence and development are closely associated with the levels of estrogenic and progesterone hormone. Extracellular signal-regulated kinase (ERK) signaling pathway abnormity is associated with a variety of tumors. This study detected estrogen receptor (ER), progesterone receptor (PR), ERK1, and ERK2 expression in EC and analyzed their correlations. A total of 40 EC patients in our hospital were selected as test group, while another 40 healthy volunteers were enrolled as control group. ER, PR, ERK1, and ERK2 expression in EC tissue, para-carcinoma tissue, and normal endometrial tissue were detected by immunohistochemistry and Western blot. The positive rate of ER, PR, ERK1, and ERK2 in the test group was 50%, 40%, 60%, and 65%, respectively, which were significantly higher than those in the control (PPR, ERK1, and ERK2 protein expressions in EC cell were significantly higher than those in the control (PPR (PPR, which were correlated with higher levels of ERK1 and ERK2, suggesting they might be involved in the pathogenesis of EC.

SPRY4-mediated ERK1/2 signaling inhibition abolishes 17β-estradiol-induced cell growth in endometrial adenocarcinoma cell.

Science.gov (United States)

Li, Mingjiang; Zhang, Hui; Zhao, Xingbo; Yan, Lei; Wang, Chong; Li, Chunyan; Li, Changzhong

2014-08-01

Basic fibroblast growth factor (FGF2)-mediated Extracellular signal-regulated kinases1/2 (ERK1/2) signaling is a critical modulator in angiogenesis. SPRY4 has been reported to be a feedback negative regulator of FGFs-induced ERK1/2 signaling. The aim of this study was to explore the role of SPRY4 in endometrial adenocarcinoma cell. The effect of SPRY4 expression on FGF2-mediated ERK1/2 signaling was detected by luciferase assay and Western blot analysis. The growth of Ishikawa cells was detected using colony formation assay and cell number counting experiment. We found that plasmid-driven SPRY4 expression efficiently blocked the activity of FGF2-induced ERK1/2 signaling in Ishikawa cells. SPRY4 expression significantly reduced the proliferation and 17β-estradiol-induced proliferation of Ishikawa cells. SPRY4 may function as a tumor suppressor in endometrial adenocarcinoma.

Crosstalk between Smad and Mitogen-Activated Protein Kinases for the Regulation of Apoptosis in Cyclosporine A- Induced Renal Tubular Injury

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Hideyuki Iwayama

2011-10-01

Full Text Available Background/Aims: It remains elusive whether there is a crosstalk between Smad and mitogen-activated protein kinases (MAPKs and whether it regulates cyclosporine A (CyA-induced apoptosis in renal proximal tubular cells (RPTCs. Methods: The effect of CyA on nuclear translocation of Smad2/3 and MAPKs (measured by Western blotting or immunofluorescence and apoptosis (determined by Hoechst 33258 staining was examined in HK-2 cells. Results: CyA induced apoptosis at 24 h and nuclear translocation of phosphorylated (p-Smad2/3 at 3 h, which was continued till 24 h. CyA enhanced the expression of p-ERK at 1 h, which was continued till 24 h, and of p-p38MAPK at 1–6 h, which returned to control level at 12 h. CyA did not affect JNK. An inhibitor of ERK, PD98059, prevented CyA-induced nuclear translocation of Smad2/3 and apoptosis. An inhibitor of p38MAPK, SB202190, deteriorated CyA-induced nuclear translocation of p-Smad2/3. Epidermal growth factor (EGF activated ERK and p38MAPK but not JNK. EGF-induced activation of MAPKs ameliorated CyA-induced nuclear translocation of p-Smad2/3 and apoptosis. Inhibition of p38MAPK but not of ERK abolished the protective effect of EGF on CyA-induced nuclear translocation of p-Smad2/3 and apoptosis. Conclusion: Crosstalk between R-Smad and p38MAPK/ERK, but not JNK differentially regulates apoptosis in CyA-induced RPTC injury.

The angiotensin type 1 receptor activates extracellular signal-regulated kinases 1 and 2 by G protein-dependent and -independent pathways in cardiac myocytes and langendorff-perfused hearts

DEFF Research Database (Denmark)

Aplin, Mark; Christensen, Gitte Lund; Schneider, Mikael

2007-01-01

The angiotensin II (AngII) type 1 receptor (AT(1)R) has been shown to activate extracellular signal-regulated kinases 1 and 2 (ERK1/2) through G proteins or G protein-independently through beta-arrestin2 in cellular expression systems. As activation mechanisms may greatly influence the biological...... effects of ERK1/2 activity, differential activation of the AT(1)R in its native cellular context could have important biological and pharmacological implications. To examine if AT(1)R activates ERK1/2 by G protein-independent mechanisms in the heart, we used the [Sar(1), Ile(4), Ile(8)]-AngII ([SII] Ang......II) analogue in native preparations of cardiac myocytes and beating hearts. We found that [SII] AngII does not activate G(q)-coupling, yet stimulates the beta-arrestin2-dependent ERK1/2. The G(q)-activated pool of ERK1/2 rapidly translocates to the nucleus, while the beta-arrestin2-scaffolded pool remains...

Autophagy Stimulus Promotes Early HuR Protein Activation and p62/SQSTM1 Protein Synthesis in ARPE-19 Cells by Triggering Erk1/2, p38MAPK, and JNK Kinase Pathways

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Nicoletta Marchesi

2018-01-01

Full Text Available RNA-binding protein dysregulation and altered expression of proteins involved in the autophagy/proteasome pathway play a role in many neurodegenerative disease onset/progression, including age-related macular degeneration (AMD. HuR/ELAVL1 is a master regulator of gene expression in human physiopathology. In ARPE-19 cells exposed to the proteasomal inhibitor MG132, HuR positively affects at posttranscriptional level p62 expression, a stress response gene involved in protein aggregate clearance with a role in AMD. Here, we studied the early effects of the proautophagy AICAR + MG132 cotreatment on the HuR-p62 pathway. We treated ARPE-19 cells with Erk1/2, AMPK, p38MAPK, PKC, and JNK kinase inhibitors in the presence of AICAR + MG132 and evaluated HuR localization/phosphorylation and p62 expression. Two-hour AICAR + MG132 induces both HuR cytoplasmic translocation and threonine phosphorylation via the Erk1/2 pathway. In these conditions, p62 mRNA is loaded on polysomes and its translation in de novo protein is favored. Additionally, for the first time, we report that JNK can phosphorylate HuR, however, without modulating its localization. Our study supports HuR’s role as an upstream regulator of p62 expression in ARPE-19 cells, helps to understand better the early events in response to a proautophagy stimulus, and suggests that modulation of the autophagy-regulating kinases as potential therapeutic targets for AMD may be relevant.

The Amoebal MAP Kinase Response to Legionella pneumophila Is Regulated by DupA

OpenAIRE

Li, Zhiru; Dugan, Aisling S.; Bloomfield, Gareth; Skelton, Jason; Ivens, Alasdair; Losick, Vicki; Isberg, Ralph R.

2009-01-01

The amoeba Dictyostelium discoideum can support replication of Legionella pneumophila. Here we identify the dupA gene, encoding a putative tyrosine kinase/dual-specificity phosphatase, in a screen for D. discoideum mutants altered in allowing L. pneumophila intracellular replication. Inactivation of dupA resulted in depressed L. pneumophila growth and sustained hyperphosphorylation of the amoebal MAP kinase ERK1, consistent with loss of a phosphatase activity. Bacterial challenge of wild-type...

Morphine preconditioning confers cardioprotection in doxorubicin-induced failing rat hearts via ERK/GSK-3β pathway independent of PI3K/Akt

International Nuclear Information System (INIS)

He, Shu-Fang; Jin, Shi-Yun; Wu, Hao; Wang, Bin; Wu, Yun-Xiang; Zhang, Shu-Jie; Irwin, Michael G.; Wong, Tak-Ming; Zhang, Ye

2015-01-01

Preconditioning against myocardial ischemia–reperfusion (I/R) injury can be suppressed in some pathological conditions. This study was designed to investigate whether morphine preconditioning (MPC) exerts cardioprotection in doxorubicin (DOX)-induced heart failure in rats and the mechanisms involved. Phosphatidylinositol-3 kinase/protein kinase B (PI3K/Akt), extracellular signal-regulated kinase (ERK) and glycogen synthase kinase (GSK)-3β pathways were examined. Normal and DOX-induced failing rat hearts were subjected to I/R injury using a Langendorff perfusion system with or without MPC or ischemic preconditioning (IPC). The PI3K inhibitor (wortmannin) or ERK inhibitor (PD98059) was infused before MPC. In normal hearts, both MPC and IPC significantly reduced infarct size and the rise in lactate dehydrogenase (LDH) level caused by I/R injury. Pretreatment with wortmannin or PD98059 abrogated the protective effects of MPC and suppressed the phosphorylation of Akt, ERK and GSK-3β. In failing rat hearts, however, MPC retained its cardioprotection while IPC did not. This protective effect was abolished by PD98059 but not wortmannin. MPC increased the level of p-ERK rather than p-Akt. The phosphorylation of GSK-3β induced by MPC was reversed by PD98059 only. IPC did not elevate the expression of p-ERK, p-Akt and p-GSK-3β in failing rat hearts. We conclude that MPC is cardioprotective in rats with DOX-induced heart failure while IPC is not. The effect of MPC appears to be mediated via the ERK/GSK-3β pathway independent of PI3K/Akt. - Highlights: • Morphine and ischemic preconditioning are cardioprotective in normal rat hearts. • Ischemic preconditioning fails to confer cardioprotection in rats with heart failure. • Morphine retains cardioprotection in doxorubicin-induced heart failure. • Morphine exerts cardioprotection via the ERK/GSK-β pathway independent of PI3K/Akt.

Morphine preconditioning confers cardioprotection in doxorubicin-induced failing rat hearts via ERK/GSK-3β pathway independent of PI3K/Akt

Energy Technology Data Exchange (ETDEWEB)

He, Shu-Fang; Jin, Shi-Yun; Wu, Hao; Wang, Bin; Wu, Yun-Xiang [Department of Anesthesiology, The Second Affiliated Hospital of Anhui Medical University, Hefei 230601 (China); Zhang, Shu-Jie [Department of Ultrasound, The Second Affiliated Hospital of Anhui Medical University, Hefei 230601 (China); Irwin, Michael G.; Wong, Tak-Ming [Department of Anesthesiology, University of Hong Kong (Hong Kong); Zhang, Ye, E-mail: zhangye_hassan@aliyun.com [Department of Anesthesiology, The Second Affiliated Hospital of Anhui Medical University, Hefei 230601 (China)

2015-11-01

Preconditioning against myocardial ischemia–reperfusion (I/R) injury can be suppressed in some pathological conditions. This study was designed to investigate whether morphine preconditioning (MPC) exerts cardioprotection in doxorubicin (DOX)-induced heart failure in rats and the mechanisms involved. Phosphatidylinositol-3 kinase/protein kinase B (PI3K/Akt), extracellular signal-regulated kinase (ERK) and glycogen synthase kinase (GSK)-3β pathways were examined. Normal and DOX-induced failing rat hearts were subjected to I/R injury using a Langendorff perfusion system with or without MPC or ischemic preconditioning (IPC). The PI3K inhibitor (wortmannin) or ERK inhibitor (PD98059) was infused before MPC. In normal hearts, both MPC and IPC significantly reduced infarct size and the rise in lactate dehydrogenase (LDH) level caused by I/R injury. Pretreatment with wortmannin or PD98059 abrogated the protective effects of MPC and suppressed the phosphorylation of Akt, ERK and GSK-3β. In failing rat hearts, however, MPC retained its cardioprotection while IPC did not. This protective effect was abolished by PD98059 but not wortmannin. MPC increased the level of p-ERK rather than p-Akt. The phosphorylation of GSK-3β induced by MPC was reversed by PD98059 only. IPC did not elevate the expression of p-ERK, p-Akt and p-GSK-3β in failing rat hearts. We conclude that MPC is cardioprotective in rats with DOX-induced heart failure while IPC is not. The effect of MPC appears to be mediated via the ERK/GSK-3β pathway independent of PI3K/Akt. - Highlights: • Morphine and ischemic preconditioning are cardioprotective in normal rat hearts. • Ischemic preconditioning fails to confer cardioprotection in rats with heart failure. • Morphine retains cardioprotection in doxorubicin-induced heart failure. • Morphine exerts cardioprotection via the ERK/GSK-β pathway independent of PI3K/Akt.

Extracellular Signal-Regulated Kinase 5 is Required for Low-Concentration H2O2-Induced Angiogenesis of Human Umbilical Vein Endothelial Cells.

Science.gov (United States)

Jiang, Shan; Zhang, Dongxin; Huang, Hong; Lei, Yonghong; Han, Yan; Han, Weidong

2017-01-01

Background . The aim of this study was to assess the effects of low concentrations of H 2 O 2 on angiogenesis of human umbilical vein endothelial cells (HUVECs) in vitro and explore the underlying mechanisms. Methods . HUVECs were cultured and stimulated with different concentrations of H 2 O 2 . Flow cytometric analysis was used to select an optimal concentration of H 2 O 2 for the following experiments. Cell proliferation, migration, and tubule formation were evaluated by Cell Counting Kit-8 (CCK-8) assays, scratch wound assays, and Matrigel tubule formation assays, respectively. For gain and loss of function studies, constitutively active MEK5 (CA-MEK5) and ERK5 shRNA lentiviruses were used to activate or knock down extracellular signal-regulated kinase 5 (ERK5). Results . We found that low concentrations of H 2 O 2 promoted HUVECs proliferation, migration, and tubule formation. ERK5 in HUVECs was significantly activated by H 2 O 2 . Enhanced ERK5 activity significantly amplified the proangiogenic effects of H 2 O 2 ; in contrast, ERK5 knock-down abrogated the effects of H 2 O 2 . Conclusions . Our results confirmed that low concentrations of H 2 O 2 promoted HUVECs angiogenesis in vitro, and ERK5 is an essential mediator of this process. Therefore, ERK5 may be a potential therapeutic target for promoting angiogenesis and improving graft survival.

Altered ERK1/2 Signaling in the Brain of Learned Helpless Rats: Relevance in Vulnerability to Developing Stress-Induced Depression

Directory of Open Access Journals (Sweden)

Yogesh Dwivedi

2016-01-01

Full Text Available Extracellular signal-regulated kinase 1/2- (ERK1/2- mediated cellular signaling plays a major role in synaptic and structural plasticity. Although ERK1/2 signaling has been shown to be involved in stress and depression, whether vulnerability to develop depression is associated with abnormalities in ERK1/2 signaling is not clearly known. The present study examined ERK1/2 signaling in frontal cortex and hippocampus of rats that showed vulnerability (learned helplessness, (LH or resiliency (non-learned helplessness, (non-LH to developing stress-induced depression. In frontal cortex and hippocampus of LH rats, we found that mRNA and protein expressions of ERK1 and ERK2 were significantly reduced, which was associated with their reduced activation and phosphorylation in cytosolic and nuclear fractions, where ERK1 and ERK2 target their substrates. In addition, ERK1/2-mediated catalytic activities and phosphorylation of downstream substrates RSK1 (cytosolic and nuclear and MSK1 (nuclear were also lower in the frontal cortex and hippocampus of LH rats without any change in their mRNA or protein expression. None of these changes were evident in non-LH rats. Our study indicates that ERK1/2 signaling is differentially regulated in LH and non-LH rats and suggests that abnormalities in ERK1/2 signaling may be crucial in the vulnerability to developing depression.

Protein Kinase C alpha (PKCα) dependent signaling mediates endometrial cancer cell growth and tumorigenesis

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Haughian, James M.; Reno, Elaine M.; Thorne, Alicia M.; Bradford, Andrew P.

2009-01-01

Endometrial cancer is the most common invasive gynecologic malignancy, yet molecular mechanisms and signaling pathways underlying its etiology and pathophysiology remain poorly characterized. We sought to define a functional role for the protein kinase C (PKC) isoform, PKCα, in an established cell model of endometrial adenocarcinoma. Ishikawa cells depleted of PKCα protein grew slower, formed fewer colonies in anchorage-independent growth assays and exhibited impaired xenograft tumor formation in nude mice. Consistent with impaired growth, PKCα knockdown increased levels of the cyclin dependent kinase (CDK) inhibitors p21Cip1/WAF1 (p21) and p27Kip1 (p27). Despite the absence of functional phosphatase and tensin homologue (PTEN) protein in Ishikawa cells, PKCα knockdown reduced Akt phosphorylation at serine 473 and concomitantly inhibited phosphorylation of the Akt target, glycogen synthase kinase-3β (GSK-3β). PKCα knockdown also resulted in decreased basal ERK phosphorylation and attenuated ERK activation following EGF stimulation. p21 and p27 expression was not increased by treatment of Ishikawa cells with ERK and Akt inhibitors, suggesting PKCα regulates CDK expression independently of Akt and ERK. Immunohistochemical analysis of grade 1 endometrioid adenocarcinoma revealed aberrant PKCα expression, with foci of elevated PKCα staining, not observed in normal endometrium. These studies demonstrate a critical role for PKCα signaling in endometrial tumorigenesis by regulating expression of CDK inhibitors p21 and p27 and activation of Akt and ERK dependent proliferative pathways. Thus, targeting PKCα may provide novel therapeutic options in endometrial tumors. PMID:19672862

Proteomic analysis reveals a role for Bcl2-associated athanogene 3 and major vault protein in resistance to apoptosis in senescent cells by regulating ERK1/2 activation.

Science.gov (United States)

Pasillas, Martina P; Shields, Sarah; Reilly, Rebecca; Strnadel, Jan; Behl, Christian; Park, Robin; Yates, John R; Klemke, Richard; Gonias, Steven L; Coppinger, Judith A

2015-01-01

Senescence is a prominent solid tumor response to therapy in which cells avoid apoptosis and instead enter into prolonged cell cycle arrest. We applied a quantitative proteomics screen to identify signals that lead to therapy-induced senescence and discovered that Bcl2-associated athanogene 3 (Bag3) is up-regulated after adriamycin treatment in MCF7 cells. Bag3 is a member of the BAG family of co-chaperones that interacts with Hsp70. Bag3 also regulates major cell-signaling pathways. Mass spectrometry analysis of the Bag3 Complex revealed a novel interaction between Bag3 and Major Vault Protein (MVP). Silencing of Bag3 or MVP shifts the cellular response to adriamycin to favor apoptosis. We demonstrate that Bag3 and MVP contribute to apoptosis resistance in therapy-induced senescence by increasing the level of activation of extracellular signal-regulated kinase1/2 (ERK1/2). Silencing of either Bag3 or MVP decreased ERK1/2 activation and promoted apoptosis in adriamycin-treated cells. An increase in nuclear accumulation of MVP is observed during therapy-induced senescence and the shift in MVP subcellular localization is Bag3-dependent. We propose a model in which Bag3 binds to MVP and facilitates MVP accumulation in the nucleus, which sustains ERK1/2 activation. We confirmed that silencing of Bag3 or MVP shifts the response toward apoptosis and regulates ERK1/2 activation in a panel of diverse breast cancer cell lines. This study highlights Bag3-MVP as an important complex that regulates a potent prosurvival signaling pathway and contributes to chemotherapy resistance in breast cancer. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Differential extracellular signal-regulated kinases 1 and 2 activation by the angiotensin type 1 receptor supports distinct phenotypes of cardiac myocytes

DEFF Research Database (Denmark)

Aplin, Mark; Christensen, Gitte Lund; Schneider, Mikael

2007-01-01

that phosphorylates p90 Ribosomal S6 Kinase, a ubiquitous and versatile mediator of ERK1/2 signal transduction. Moreover, the beta-arrestin2-dependent ERK1/2 signal supports intact proliferation of cardiac myocytes. In contrast to G(q)-activated ERK1/2, and in keeping with its failure to translocate to the nucleus...

Sodium appetite elicited by low-sodium diet is dependent on p44/42 mitogen-activated protein kinase (extracellular signal-regulated kinase 1/2) activation in the brain.

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Monteiro, L R N; Marangon, P B; Elias, L L K; Reis, L C; Antunes-Rodrigues, J; Mecawi, A S

2017-09-01

Sodium appetite is regulated by several signalling molecules, among which angiotensin II (Ang II) serves as a key driver of robust salt intake by binding to Ang II type 1 receptors (AT1R) in several regions in the brain. The activation of these receptors recruits the mitogen-activated protein kinase (MAPK) pathway, which has previously been linked to Ang II-induced increases in sodium appetite. Thus, we addressed the involvement of MAPK signalling in the induction of sodium appetite after 4 days of low-sodium diet consumption. An increase in extracellular signal-regulated kinase (ERK) phosphorylation in the laminae terminalis and mediobasal hypothalamus was observed after low-sodium diet consumption. This response was reduced by i.c.v. microinjection of an AT1R antagonist into the laminae terminalis but not the hypothalamus. This result indicates that low-sodium diet consumption activates the MAPK pathway via Ang II/AT1R signalling on the laminae terminalis. On the other hand, activation of the MAPK pathway in the mediobasal hypothalamus after low-sodium diet consumption appears to involve another extracellular mediator. We also evaluated whether a low-sodium diet could increase the sensitivity for Ang II in the brain and activate the MAPK pathway. However, i.c.v. injection of Ang II increased ERK phosphorylation on the laminae terminalis and mediobasal hypothalamus; this increase achieved a response magnitude similar to those observed in both the normal and low-sodium diet groups. These data indicate that low-sodium diet consumption for 4 days is insufficient to change the ERK phosphorylation response to Ang II in the brain. To investigate whether the MAPK pathway is involved in sodium appetite after low-sodium diet consumption, we performed i.c.v. microinjections of a MAPK pathway inhibitor (PD98059). PD98059 inhibited both saline and water intake after low-sodium diet consumption. Thus, the MAPK pathway is involved in promoting the sodium appetite after low

Proinflammatory effect of sodium 4-phenylbutyrate in deltaF508-cystic fibrosis transmembrane conductance regulator lung epithelial cells: involvement of extracellular signal-regulated protein kinase 1/2 and c-Jun-NH2-terminal kinase signaling.

Science.gov (United States)

Roque, Telma; Boncoeur, Emilie; Saint-Criq, Vinciane; Bonvin, Elise; Clement, Annick; Tabary, Olivier; Jacquot, Jacky

2008-09-01

Sodium 4-phenylbutyrate (4-PBA) has attracted a great deal of attention in cystic fibrosis (CF) pathology due to its capacity to traffic DeltaF508-cystic fibrosis transmembrane conductance regulator (CFTR) to the cell membrane and restore CFTR chloride function at the plasma membrane of CF lung cells in vitro and in vivo. Using two different DeltaF508-CFTR lung epithelial cell lines (CFBE41o- and IB3-1 cells, characterized with DeltaF508-homozygous and heterozygous genotype, respectively) in vitro, 4-PBA induced an increase of proinflammatory cytokine interleukin (IL)-8 production in a concentration-dependent manner. This 4-PBA-induced IL-8 production was associated with a strong reduction of proteasome and nuclear factor-kappaB transcriptional activities in the two DeltaF508-CFTR lung cells either in a resting state or after tumor necrosis factor-alpha stimulation. In contrast, a strong increase of activator protein-1 transcriptional activity was observed. The inhibition of extracellular signal-regulated protein kinase 1/2 (ERK1/2) by 1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio] butadiene (U0126) and 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one (PD98059) and c-Jun-NH(2)-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) by anthra[1,9-cd] pyrazol-6 (2H)-one (SP600125), respectively, was associated with a reduction (2-3.5-fold) of IL-8 production in both DeltaF508-CFTR lung cell lines treated with 4-PBA. No significant change of IL-8 production was observed after an inhibition of p38 MAPK with 4-[4-(4-fluorophenyl)-5-(4-pyridinyl)-1H-imidazol-2-yl] phenol (SB202190). Therefore, we suggest that inhibition of both ERK1/2 and JNK signaling may be a means to strongly reduce 4-PBA-induced IL-8 production in combination with 4-PBA treatment to restore CFTR Cl(-) channel function in lung epithelial cells of patients with CF.

Activation of Erk and JNK MAPK pathways by acute swim stress in rat brain regions

Directory of Open Access Journals (Sweden)

Salvadore Christopher

2004-09-01

Full Text Available Abstract Background The mitogen-activated protein kinases (MAPKs have been shown to participate in a wide array of cellular functions. A role for some MAPKs (e.g., extracellular signal-regulated kinase, Erk1/2 has been documented in response to certain physiological stimuli, such as ischemia, visceral pain and electroconvulsive shock. We recently demonstrated that restraint stress activates the Erk MAPK pathway, but not c-Jun-N-terminal kinase/stress-activated protein kinase (JNK/SAPK or p38MAPK, in several rat brain regions. In the present study, we investigated the effects of a different stressor, acute forced swim stress, on the phosphorylation (P state of these MAPKs in the hippocampus, neocortex, prefrontal cortex, amygdala and striatum. In addition, effects on the phosphorylation state of the upstream activators of the MAPKs, their respective MAPK kinases (MAPKKs; P-MEK1/2, P-MKK4 and P-MKK3/6, were determined. Finally, because the Erk pathway can activate c-AMP response element (CRE binding (CREB protein, and swim stress has recently been reported to enhance CREB phosphorylation, changes in P-CREB were also examined. Results A single 15 min session of forced swimming increased P-Erk2 levels 2–3-fold in the neocortex, prefrontal cortex and striatum, but not in the hippocampus or amygdala. P-JNK levels (P-JNK1 and/or P-JNK2/3 were increased in all brain regions about 2–5-fold, whereas P-p38MAPK levels remained essentially unchanged. Surprisingly, levels of the phosphorylated MAPKKs, P-MEK1/2 and P-MKK4 (activators of the Erk and JNK pathways, respectively were increased in all five brain regions, and much more dramatically (P-MEK1/2, 4.5 to > 100-fold; P-MKK4, 12 to ~300-fold. Consistent with the lack of forced swim on phosphorylation of p38MAPK, there appeared to be no change in levels of its activator, P-MKK3/6. P-CREB was increased in all but cortical (prefrontal, neocortex areas. Conclusions Swim stress specifically and markedly

Anti-glycophorin C induces mitochondrial membrane depolarization and a loss of extracellular regulated kinase 1/2 protein kinase activity that is prevented by pretreatment with cytochalasin D: implications for hemolytic disease of the fetus and newborn caused by anti-Ge3.

Science.gov (United States)

Micieli, Jonathan A; Wang, Duncheng; Denomme, Gregory A

2010-08-01

Anti-glycophorin C (GPC), blood group antibodies of which cause hemolytic disease of the fetus and newborn (HDFN), is a potent inhibitor of erythroid progenitor cell growth. The cellular mechanism for growth inhibition has not been characterized. K562 cells were incubated in the presence of either anti-GPC, an immunoglobulin G isotype control, an inhibitor of actin polymerization called cytochalasin D with anti-GPC, or cytochalasin D alone. The JC-1 cationic dye was used to detect mitochondrial depolarization and the activity of the mitogen-activated protein kinases was assessed by Western blotting. Anti-GPC inhibits the activity of extracellular regulated kinase (ERK)1/2 within 10 minutes but does not alter the activity of p38 or c-Jun N-terminal kinase. After 24 hours there was a significant loss of mitochondrial membrane potential compared to isotype control–treated cells. Both the ERK1/2 inhibition and the loss of mitochondrial potential were prevented by pretreatment with cytochalasin D. A cell surface antibody can cause anemia by altering the signaling pathways in erythroid cells by promoting depolarization of mitochondria via cytoskeletal rearrangement. The observation that neonates with anti-GPC HDFN are unresponsive to erythropoietin can be explained by the antibody inhibiting a protein kinase through which this hematopoietic growth factor achieves its effects.

Extracellular signal-regulated kinase 1 and 2 are not required for GnRH neuron development and normal female reproductive axis function in mice.

Science.gov (United States)

Wierman, Margaret E; Xu, Mei; Pierce, A; Bliesner, B; Bliss, S P; Roberson, M S

2012-01-01

Selective deletion of extracellular signal-regulated kinase (ERK) 1 and ERK2 in the pituitary gonadotrope and ovarian granulosa cells disrupts female reproductive axis function. Thus, we asked if ERK1 and ERK2 are critical for GnRH neuron ontogeny or the central control of female reproductive function. GnRH-Cre-recombinase (Cre+) expressing mice were crossed with mice with a global deletion of ERK1 and a floxed ERK2 allele (Erk1-/Erk2fl/fl) to selectively delete ERK2 in GnRH neurons. Cre-recombinase mRNA was selectively expressed in the brain of Cre+ mice. GnRH neuron number and location were determined during embryogenesis and in the adult. GnRH neuron counts at E15 did not differ between experimental and control groups (1,198 ± 65 and 1,160 ± 80 respectively, p = NS). In adults, numbers of GnRH neurons in the GnRHCre+Erk1-/Erk2- mice (741 ± 157) were similar to those in controls (756 ± 7), without alteration in their distribution across the forebrain. ERK1 and 2 deficiency did not alter the timing of vaginal opening, age at first estrus, or estrous cyclicity. Although ERK1 and 2 are components of a dominant signaling pathway in GnRH neuronal cells that modulates survival and control of GnRH gene expression, other signaling pathways compensate for their deletion in vivo to allow GnRH neuron survival and targeting and normal onset of female sexual maturation and reproductive function. In contrast to effects at the pituitary and the ovary, ERK1 and ERK2 are dispensable at the level of the GnRH neuron. Copyright © 2011 S. Karger AG, Basel.

The human transient receptor potential vanilloid 3 channel is sensitized via the ERK pathway

Czech Academy of Sciences Publication Activity Database

Vyklická, Lenka; Boukalová, Štěpána; Mačíková, Lucie; Chvojka, Štěpán; Vlachová, Viktorie

2017-01-01

Roč. 292, č. 51 (2017), s. 21083-21091 ISSN 0021-9258 R&D Projects: GA ČR(CZ) GA15-15839S Institutional support: RVO:67985823 Keywords : epidermal growth factor receptor (EGFR) * extracellular-signal-regulated kinase (ERK) * keratinocyte * phosphorylation * transient receptor potential channels * TRP channels Subject RIV: FH - Neurology OBOR OECD: Neurosciences (including psychophysiology Impact factor: 4.125, year: 2016

Efficient inhibition of the formation of joint adhesions by ERK2 small interfering RNAs

International Nuclear Information System (INIS)

Li, Fengfeng; Ruan, Hongjiang; Fan, Cunyi; Zeng, Bingfang; Wang, Chunyang; Wang, Xiang

2010-01-01

Transforming growth factor-β1 and fibroblast growth factor-2 play very important roles in fibroblast proliferation and collagen expression. These processes lead to the formation of joint adhesions through the SMAD and MAPK pathways, in which extracellular signal-regulated kinase (ERK)2 is considered to be crucial. Based on these theories, we examined the effects of a lentivirus-mediated small interfering RNA (siRNA) targeting ERK2 on the suppression of joint adhesion formation in vivo. The effects were assessed in vivo from different aspects including the adhesion score, histology and joint contracture angle. We found that the adhesions in the ERK2 siRNA group became soft and weak, and were easily stretched. Accordingly, the flexion contracture angles in the ERK2 siRNA group were also reduced (P < 0.05 compared with the control group). The animals appeared healthy, with no signs of impaired wound healing. In conclusion, local delivery of a lentivirus-mediated siRNA targeting ERK2 can ameliorate joint adhesion formation effectively and safely.

Ghrelin augments murine T-cell proliferation by activation of the phosphatidylinositol-3-kinase, extracellular signal-regulated kinase and protein kinase C signaling pathways

Science.gov (United States)

Lee, Jun Ho; Patel, Kalpesh; Tae, Hyun Jin; Lustig, Ana; Kim, Jie Wan; Mattson, Mark P.; Taub, Dennis D.

2014-01-01

Thymic atrophy occurs during normal aging, and is accelerated by exposure to chronic stressors that elevate glucocorticoid levelsand impair the naïve T cell output. The orexigenic hormone ghrelin was recently shown to attenuate age-associated thymic atrophy. Here, we report that ghrelin enhances the proliferation of murine CD4+ primary T cells and a CD4+ T-cell line. Ghrelin induced activation of the ERK1/2 and Akt signaling pathways, via upstream activation of phosphatidylinositol-3-kinase and protein kinase C, to enhance T-cell proliferation. Moreover, ghrelin induced expression of the cell cycle proteins cyclin D1, cyclin E, cyclin-dependent kinase 2 (CDK2) and retinoblastoma phosphorylation. Finally, ghrelin activated the above-mentioned signaling pathways and stimulated thymocyte proliferation in young and older mice in vivo. PMID:25447526

DA-9801 promotes neurite outgrowth via ERK1/2-CREB pathway in PC12 cells.

Science.gov (United States)

Won, Jong Hoon; Ahn, Kyong Hoon; Back, Moon Jung; Ha, Hae Chan; Jang, Ji Min; Kim, Ha Hyung; Choi, Sang-Zin; Son, Miwon; Kim, Dae Kyong

2015-01-01

In the present study, we examined the mechanisms underlying the effect of DA-9801 on neurite outgrowth. We found that DA-9801 elicits its effects via the mitogen-activated protein kinase (MEK) extracellular signal-regulated kinase (ERK)1/2-cAMP response element-binding protein (CREB) pathway. DA-9801, an extract from a mixture of Dioscorea japonica and Dioscorea nipponica, was reported to promote neurite outgrowth in PC12 cells. The effects of DA-9801 on cell viability and expression of neuronal markers were evaluated in PC12 cells. To investigate DA-9801 action, specific inhibitors targeting the ERK signaling cascade were used. No cytotoxicity was observed in PC12 cells at DA-9801 concentrations of less than 30 µg/mL. In the presence of nerve growth factor (NGF, 2 ng/mL), DA-9801 promoted neurite outgrowth and increased the relative mRNA levels of neurofilament-L (NF-L), a marker of neuronal differentiation. The Raf-1 inhibitor GW5074 and MEK inhibitor PD98059 significantly attenuated DA-9801-induced neurite outgrowth. Additionally, the MEK1 and MEK2 inhibitor SL327 significantly attenuated the increase in the percentage of neurite-bearing PC12 cells induced by DA-9801 treatment. Conversely, the selective p38 mitogen-activated protein kinase inhibitor SB203580 did not attenuate the DA-9801 treatment-induced increase in the percentage of neurite-bearing PC12 cells. DA-9801 enhanced the phosphorylation of ERK1/2 and CREB in PC12 cells incubated with and without NGF. Pretreatment with PD98059 blocked the DA-9801-induced phosphorylation of ERK1/2 and CREB. In conclusion, DA-9801 induces neurite outgrowth by affecting the ERK1/2-CREB signaling pathway. Insights into the mechanism underlying this effect of DA-9801 may suggest novel potential strategies for the treatment of peripheral neuropathy.

Differentiation of C2C12 myoblasts expressing lamin A mutated at a site responsible for Emery-Dreifuss muscular dystrophy is improved by inhibition of the MEK-ERK pathway and stimulation of the PI3-kinase pathway

International Nuclear Information System (INIS)

Favreau, Catherine; Delbarre, Erwan; Courvalin, Jean-Claude; Buendia, Brigitte

2008-01-01

Mutation R453W in A-type lamins, that are major nuclear envelope proteins, generates Emery-Dreifuss muscular dystrophy. We previously showed that mouse myoblasts expressing R453W-lamin A incompletely exit the cell cycle and differentiate into myocytes with a low level of multinucleation. Here we attempted to improve differentiation by treating these cells with a mixture of PD98059, an extracellular-regulated kinase (ERK) kinase (also known as mitogen-activated kinase, MEK) inhibitor, and insulin-like growth factor-II, an activator of phosphoinositide 3-kinase. We show that mouse myoblasts expressing R453W-lamin A were sensitive to the drug treatment as shown by (i) an increase in multinucleation, (ii) downregulation of proliferation markers (cyclin D1, hyperphosphorylated Rb), (iii) upregulation of myogenin, and (iv) sustained activation of p21 and cyclin D3. However, nuclear matrix anchorage of p21 and cyclin D3 in a complex with hypophosphorylated Rb that is critical to trigger cell cycle arrest and myogenin induction was deficient and incompletely restored by drug treatment. As the turn-over of R453W-lamin A at the nuclear envelope was greatly enhanced, we propose that R453W-lamin A impairs the capacity of the nuclear lamina to serve as scaffold for substrates of the MEK-ERK pathway and for MyoD-induced proteins that play a role in the differentiation process

Hypoxia Downregulates MAPK/ERK but Not STAT3 Signaling in ROS-Dependent and HIF-1-Independent Manners in Mouse Embryonic Stem Cells

Directory of Open Access Journals (Sweden)

Jan Kučera

2017-01-01

Full Text Available Hypoxia is involved in the regulation of stem cell fate, and hypoxia-inducible factor 1 (HIF-1 is the master regulator of hypoxic response. Here, we focus on the effect of hypoxia on intracellular signaling pathways responsible for mouse embryonic stem (ES cell maintenance. We employed wild-type and HIF-1α-deficient ES cells to investigate hypoxic response in the ERK, Akt, and STAT3 pathways. Cultivation in 1% O2 for 24 h resulted in the strong dephosphorylation of ERK and its upstream kinases and to a lesser extent of Akt in an HIF-1-independent manner, while STAT3 phosphorylation remained unaffected. Downregulation of ERK could not be mimicked either by pharmacologically induced hypoxia or by the overexpression. Dual-specificity phosphatases (DUSP 1, 5, and 6 are hypoxia-sensitive MAPK-specific phosphatases involved in ERK downregulation, and protein phosphatase 2A (PP2A regulates both ERK and Akt. However, combining multiple approaches, we revealed the limited significance of DUSPs and PP2A in the hypoxia-mediated attenuation of ERK signaling. Interestingly, we observed a decreased reactive oxygen species (ROS level in hypoxia and a similar phosphorylation pattern for ERK when the cells were supplemented with glutathione. Therefore, we suggest a potential role for the ROS-dependent attenuation of ERK signaling in hypoxia, without the involvement of HIF-1.

The forced swimming-induced behavioural immobility response involves histone H3 phospho-acetylation and c-Fos induction in dentate gyrus granule neurons via activation of the N-methyl-D-aspartate/extracellular signal-regulated kinase/mitogen- and stress-activated kinase signalling pathway.

Science.gov (United States)

Chandramohan, Yalini; Droste, Susanne K; Arthur, J Simon C; Reul, Johannes M H M

2008-05-01

The hippocampus is involved in learning and memory. Previously, we have shown that the acquisition of the behavioural immobility response after a forced swim experience is associated with chromatin modifications and transcriptional induction in dentate gyrus granule neurons. Given that both N-methyl-D-aspartate (NMDA) receptors and the extracellular signal-regulated kinases (ERK) 1/2 signalling pathway are involved in neuroplasticity processes underlying learning and memory, we investigated in rats and mice whether these signalling pathways regulate chromatin modifications and transcriptional events participating in the acquisition of the immobility response. We found that: (i) forced swimming evoked a transient increase in the number of phospho-acetylated histone H3-positive [P(Ser10)-Ac(Lys14)-H3(+)] neurons specifically in the middle and superficial aspects of the dentate gyrus granule cell layer; (ii) antagonism of NMDA receptors and inhibition of ERK1/2 signalling blocked forced swimming-induced histone H3 phospho-acetylation and the acquisition of the behavioural immobility response; (iii) double knockout (DKO) of the histone H3 kinase mitogen- and stress-activated kinases (MSK) 1/2 in mice completely abolished the forced swimming-induced increases in histone H3 phospho-acetylation and c-Fos induction in dentate granule neurons and the behavioural immobility response; (iv) blocking mineralocorticoid receptors, known not to be involved in behavioural immobility in the forced swim test, did not affect forced swimming-evoked histone H3 phospho-acetylation in dentate neurons; and (v) the pharmacological manipulations and gene deletions did not affect behaviour in the initial forced swim test. We conclude that the forced swimming-induced behavioural immobility response requires histone H3 phospho-acetylation and c-Fos induction in distinct dentate granule neurons through recruitment of the NMDA/ERK/MSK 1/2 pathway.

Corticotrigeminal Projections from the Insular Cortex to the Trigeminal Caudal Subnucleus Regulate Orofacial Pain after Nerve Injury via Extracellular Signal-Regulated Kinase Activation in Insular Cortex Neurons.

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Wang, Jian; Li, Zhi-Hua; Feng, Ban; Zhang, Ting; Zhang, Han; Li, Hui; Chen, Tao; Cui, Jing; Zang, Wei-Dong; Li, Yun-Qing

2015-01-01

Cortical neuroplasticity alterations are implicated in the pathophysiology of chronic orofacial pain. However, the relationship between critical cortex excitability and orofacial pain maintenance has not been fully elucidated. We recently demonstrated a top-down corticospinal descending pain modulation pathway from the anterior cingulate cortex (ACC) to the spinal dorsal horn that could directly regulate nociceptive transmission. Thus, we aimed to investigate possible corticotrigeminal connections that directly influence orofacial nociception in rats. Infraorbital nerve chronic constriction injury (IoN-CCI) induced significant orofacial nociceptive behaviors as well as pain-related negative emotions such as anxiety/depression in rats. By combining retrograde and anterograde tract tracing, we found powerful evidence that the trigeminal caudal subnucleus (Vc), especially the superficial laminae (I/II), received direct descending projections from granular and dysgranular parts of the insular cortex (IC). Extracellular signal-regulated kinase (ERK), an important signaling molecule involved in neuroplasticity, was significantly activated in the IC following IoN-CCI. Moreover, in IC slices from IoN-CCI rats, U0126, an inhibitor of ERK activation, decreased both the amplitude and the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) and reduced the paired-pulse ratio (PPR) of Vc-projecting neurons. Additionally, U0126 also reduced the number of action potentials in the Vc-projecting neurons. Finally, intra-IC infusion of U0126 obviously decreased Fos expression in the Vc, accompanied by the alleviation of both nociceptive behavior and negative emotions. Thus, the corticotrigeminal descending pathway from the IC to the Vc could directly regulate orofacial pain, and ERK deactivation in the IC could effectively alleviate neuropathic pain as well as pain-related negative emotions in IoN-CCI rats, probably through this top-down pathway. These findings may help

Chewing suppresses the stress-induced increase in the number of pERK-immunoreactive cells in the periaqueductal grey.

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Yamada, Kentaro; Narimatsu, Yuri; Ono, Yumie; Sasaguri, Ken-Ichi; Onozuka, Minoru; Kawata, Toshitsugu; Yamamoto, Toshiharu

2015-07-10

We investigated the effects of chewing under immobilization stress on the periaqueductal gray (PAG) matter using phosphorylated extracellular signal-regulated kinase (pERK) as a marker of responding cells. Immobilization stress increased pERK-immunoreactive cells in the PAG. Among four subdivisions of the PAG, the increase of immunoreactive cells was remarkable in the dorsolateral and ventrolateral subdivisions. However, increase of pERK-immunoreactive cells by the immobilization stress was not so evident in the dorsomedial and lateral subdivisions. The chewing under immobilization stress prevented the stress-induced increase of pERK-immunoreactive cells in the dorsolateral and ventrolateral subdivisions with statistical significances (p<0.05). Again, chewing effects on pERK-immunoreactive cells were not visible in the dorsomedial and lateral subdivisions. These results suggest that the chewing alleviates the PAG (dorsolateral and ventrolateral subdivisions) responses to stress. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

A-RAF kinase functions in ARF6 regulated endocytic membrane traffic.

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Elena Nekhoroshkova

Full Text Available BACKGROUND: RAF kinases direct ERK MAPK signaling to distinct subcellular compartments in response to growth factor stimulation. METHODOLOGY/PRINCIPAL FINDINGS: Of the three mammalian isoforms A-RAF is special in that one of its two lipid binding domains mediates a unique pattern of membrane localization. Specific membrane binding is retained by an N-terminal fragment (AR149 that corresponds to a naturally occurring splice variant termed DA-RAF2. AR149 colocalizes with ARF6 on tubular endosomes and has a dominant negative effect on endocytic trafficking. Moreover actin polymerization of yeast and mammalian cells is abolished. AR149/DA-RAF2 does not affect the internalization step of endocytosis, but trafficking to the recycling compartment. CONCLUSIONS/SIGNIFICANCE: A-RAF induced ERK activation is required for this step by activating ARF6, as A-RAF depletion or inhibition of the A-RAF controlled MEK-ERK cascade blocks recycling. These data led to a new model for A-RAF function in endocytic trafficking.

Ionizing radiation-induced MEK and Erk activation does not enhance survival of irradiated human squamous carcinoma cells

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Bonner, James A.; Vroman, Benjamin T.; Christianson, Teresa J.H.; Karnitz, Larry M.

1998-01-01

Purpose: Ionizing radiation (IR) triggers several intracellular signaling cascades that have commonly been regarded as mitogenic, including the Raf-MEK-Erk kinase cascade. In addition to promoting proliferation, activated MEK and Erk may also prevent cell death induced by cytotoxic stimuli. Because Raf, MEK, and Erk are activated by IR in some tumor cell lines, this suggests that IR-induced activation of the kinase cascade may enhance the survival of irradiated cells. Methods and Materials: IR-induced activation of MEK and Erk was assessed in irradiated UM-SCC-6 cells, a human squamous carcinoma cell line. Activation of MEK and Erk was blocked with the pharmacological inhibitor of MEK activation, PD098059. Clonogenic survival was assessed in irradiated UM-SCC-6 cells that were pretreated with nothing or with the MEK inhibitor. Results: In UM-SCC-6 cells, IR doses as low as 2 Gy rapidly activated MEK and Erk. Pretreatment of the cells with the pharmacological inhibitor of MEK activation, PD098059, effectively blocked IR-induced activation of MEK and Erk. However, inhibition of the kinase cascade did not affect the clonogenic survival of irradiated cells in either early or delayed-plating experiments. Conclusion: Taken together, these results suggest that although MEK and Erk are rapidly activated by IR treatment, these protein kinases do not affect the clonogenic survival of irradiated UM-SCC6 cells

Follicle-stimulating hormone (FSH) activates extracellular signal-regulated kinase phosphorylation independently of beta-arrestin- and dynamin-mediated FSH receptor internalization

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Piketty, Vincent; Kara, Elodie; Guillou, Florian; Reiter, Eric; Crepieux, Pascale

2006-01-01

Background The follicle-stimulating hormone receptor (FSH-R) is a seven transmembrane spanning receptor (7TMR) which plays a crucial role in male and female reproduction. Upon FSH stimulation, the FSH-R activates the extracellular signal-regulated kinases (ERK). However, the mechanisms whereby the agonist-stimulated FSH-R activates ERK are poorly understood. In order to activate ERK, some 7 TMRs require beta-arrestin-and dynamin-dependent internalization to occur, whereas some others do not. In the present study, we examined the ability of the FSH-activated FSH-R to induce ERK phosphorylation, in conditions where its beta-arrestin- and dynamin-mediated internalization was impaired. Methods Human embryonic kidney (HEK) 293 cells were transiently transfected with the rat FSH-R. Internalization of the FSH-R was manipulated by co-expression of either a beta-arrestin (319–418) dominant negative peptide, either an inactive dynamin K44A mutant or of wild-type beta-arrestin 1 or 2. The outcomes on the FSH-R internalization were assayed by measuring 125I-FSH binding at the cell surface when compared to internalized 125I-FSH binding. The resulting ERK phosphorylation level was visualized by Western blot analysis. Results In HEK 293 cells, FSH stimulated ERK phosphorylation in a dose-dependent manner. Co-transfection of the beta- arrestin (319–418) construct, or of the dynamin K44A mutant reduced FSH-R internalization in response to FSH, without affecting ERK phosphorylation. Likewise, overexpression of wild-type beta-arrestin 1 or 2 significantly increased the FSH-R internalization level in response to FSH, without altering FSH-induced ERK phosphorylation. Conclusion From these results, we conclude that the FSH-R does not require beta-arrestin- nor dynamin-mediated internalization to initiate ERK phosphorylation in response to FSH. PMID:16787538

Identification of extracellular signal-regulated kinase 3 as a new interaction partner of cyclin D3

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Sun Maoyun; Wei Yuanyan; Yao Luyang; Xie Jianhui; Chen Xiaoning; Wang Hanzhou; Jiang Jianhai; Gu Jianxin

2006-01-01

Cyclin D3, like cyclin D1 and D2 isoforms, is a crucial component of the core cell cycle machinery in mammalian cells. It also exhibits its unique properties in many other physiological processes. In the present study, using yeast two-hybrid screening, we identified ERK3, an atypical mitogen-activated protein kinase (MAPK), as a cyclin D3 binding partner. GST pull-down assays showed that cyclin D3 interacts directly and specifically with ERK3 in vitro. The binding of cyclin D3 and ERK3 was further confirmed in vivo by co-immunoprecipitation assay and confocal microscopic analysis. Moreover, carboxy-terminal extension of ERK3 was responsible for its association with intact cyclin D3. These findings further expand distinct roles of cyclin D3 and suggest the potential activity of ERK3 in cell proliferation

Indirubin-3-Oxime Prevents H2O2-Induced Neuronal Apoptosis via Concurrently Inhibiting GSK3β and the ERK Pathway.

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Yu, Jie; Zheng, Jiacheng; Lin, Jiajia; Jin, Linlu; Yu, Rui; Mak, Shinghung; Hu, Shengquan; Sun, Hongya; Wu, Xiang; Zhang, Zaijun; Lee, Mingyuen; Tsim, Wahkeung; Su, Wei; Zhou, Wenhua; Cui, Wei; Han, Yifan; Wang, Qinwen

2017-05-01

Oxidative stress-induced neuronal apoptosis plays an important role in many neurodegenerative disorders. In this study, we have shown that indirubin-3-oxime, a derivative of indirubin originally designed for leukemia therapy, could prevent hydrogen peroxide (H 2 O 2 )-induced apoptosis in both SH-SY5Y cells and primary cerebellar granule neurons. H 2 O 2 exposure led to the increased activities of glycogen synthase kinase 3β (GSK3β) and extracellular signal-regulated kinase (ERK) in SH-SY5Y cells. Indirubin-3-oxime treatment significantly reversed the altered activity of both the PI3-K/Akt/GSK3β cascade and the ERK pathway induced by H 2 O 2 . In addition, both GSK3β and mitogen-activated protein kinase inhibitors significantly prevented H 2 O 2 -induced neuronal apoptosis. Moreover, specific inhibitors of the phosphoinositide 3-kinase (PI3-K) abolished the neuroprotective effects of indirubin-3-oxime against H 2 O 2 -induced neuronal apoptosis. These results strongly suggest that indirubin-3-oxime prevents H 2 O 2 -induced apoptosis via concurrent inhibiting GSK3β and the ERK pathway in SH-SY5Y cells, providing support for the use of indirubin-3-oxime to treat neurodegenerative disorders caused or exacerbated by oxidative stress.

Adenosine A2A receptor-dependent proliferation of pulmonary endothelial cells is mediated through calcium mobilization, PI3-kinase and ERK1/2 pathways

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Ahmad, Aftab; Schaack, Jerome B.; White, Carl W.; Ahmad, Shama

2013-01-01

Highlights: •A 2A receptor-induced pulmonary endothelial growth is mediated by PI3K and ERK1/2. •Cytosolic calcium mobilization is also critical for pulmonary endothelial growth. •Effectors of A 2A receptor, like tyrosine kinases and cAMP increase PI3K/Akt signaling. •Activation of A 2A receptor can contribute to vascular remodeling. -- Abstract: Hypoxia and HIF-2α-dependent A 2A receptor expression and activation increase proliferation of human lung microvascular endothelial cells (HLMVECs). This study was undertaken to investigate the signaling mechanisms that mediate the proliferative effects of A 2A receptor. A 2A receptor-mediated proliferation of HLMVECs was inhibited by intracellular calcium chelation, and by specific inhibitors of ERK1/2 and PI3-kinase (PI3K). The adenosine A 2A receptor agonist CGS21680 caused intracellular calcium mobilization in controls and, to a greater extent, in A 2A receptor-overexpressing HLMVECs. Adenoviral-mediated A 2A receptor overexpression as well as receptor activation by CGS21680 caused increased PI3K activity and Akt phosphorylation. Cells overexpressing A 2A receptor also manifested enhanced ERK1/2 phosphorylation upon CGS21680 treatment. A 2A receptor activation also caused enhanced cAMP production. Likewise, treatment with 8Br-cAMP increased PI3K activity. Hence A 2A receptor-mediated cAMP production and PI3K and Akt phosphorylation are potential mediators of the A 2A -mediated proliferative response of HLMVECs. Cytosolic calcium mobilization and ERK1/2 phosphorylation are other critical effectors of HLMVEC proliferation and growth. These studies underscore the importance of adenosine A 2A receptor in activation of survival and proliferative pathways in pulmonary endothelial cells that are mediated through PI3K/Akt and ERK1/2 pathways

Halofuginone inhibits Smad3 phosphorylation via the PI3K/Akt and MAPK/ERK pathways in muscle cells: Effect on myotube fusion

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Roffe, Suzy; Hagai, Yosey; Pines, Mark; Halevy, Orna

2010-01-01

Halofuginone, a novel inhibitor of Smad3 phosphorylation, has been shown to inhibit muscle fibrosis and to improve cardiac and skeletal muscle functions in the mdx mouse model of Duchenne muscular dystrophy. Here, we demonstrate that halofuginone promotes the phosphorylation of Akt and mitogen-activated protein kinase (MAPK) family members in a C2 muscle cell line and in primary myoblasts derived from wild-type and mdx mice diaphragms. Halofuginone enhanced the association of phosphorylated Akt and MAPK/extracellular signal-regulated protein kinase (ERK) with the non-phosphorylated form of Smad3, accompanied by a reduction in Smad3 phosphorylation levels. This reduction was reversed by inhibitors of the phosphoinositide 3'-kinase/Akt (PI3K/Akt) and MAPK/ERK pathways, suggesting their specific role in mediating halofuginone's inhibitory effect on Smad3 phosphorylation. Halofuginone enhanced Akt, MAPK/ERK and p38 MAPK phosphorylation and inhibited Smad3 phosphorylation in myotubes, all of which are crucial for myotube fusion. In addition, halofuginone increased the association Akt and MAPK/ERK with Smad3. As a consequence, halofuginone promoted myotube fusion, as reflected by an increased percentage of C2 and mdx myotubes containing high numbers of nuclei, and this was reversed by specific inhibitors of the PI3K and MAPK/ERK pathways. Together, the data suggest a role, either direct or via inhibition of Smad3 phosphorylation, for Akt or MAPK/ERK in halofuginone-enhanced myotube fusion, a feature which is crucial to improving muscle function in muscular dystrophies.

Halofuginone inhibits Smad3 phosphorylation via the PI3K/Akt and MAPK/ERK pathways in muscle cells: Effect on myotube fusion

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Roffe, Suzy [Department of Animal Sciences, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100 (Israel); Hagai, Yosey [Department of Animal Sciences, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100 (Israel); Institute of Animal Sciences, Volcani Center, Bet Dagan 50250 (Israel); Pines, Mark [Institute of Animal Sciences, Volcani Center, Bet Dagan 50250 (Israel); Halevy, Orna, E-mail: halevyo@agri.huji.ac.il [Department of Animal Sciences, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100 (Israel)

2010-04-01

Halofuginone, a novel inhibitor of Smad3 phosphorylation, has been shown to inhibit muscle fibrosis and to improve cardiac and skeletal muscle functions in the mdx mouse model of Duchenne muscular dystrophy. Here, we demonstrate that halofuginone promotes the phosphorylation of Akt and mitogen-activated protein kinase (MAPK) family members in a C2 muscle cell line and in primary myoblasts derived from wild-type and mdx mice diaphragms. Halofuginone enhanced the association of phosphorylated Akt and MAPK/extracellular signal-regulated protein kinase (ERK) with the non-phosphorylated form of Smad3, accompanied by a reduction in Smad3 phosphorylation levels. This reduction was reversed by inhibitors of the phosphoinositide 3'-kinase/Akt (PI3K/Akt) and MAPK/ERK pathways, suggesting their specific role in mediating halofuginone's inhibitory effect on Smad3 phosphorylation. Halofuginone enhanced Akt, MAPK/ERK and p38 MAPK phosphorylation and inhibited Smad3 phosphorylation in myotubes, all of which are crucial for myotube fusion. In addition, halofuginone increased the association Akt and MAPK/ERK with Smad3. As a consequence, halofuginone promoted myotube fusion, as reflected by an increased percentage of C2 and mdx myotubes containing high numbers of nuclei, and this was reversed by specific inhibitors of the PI3K and MAPK/ERK pathways. Together, the data suggest a role, either direct or via inhibition of Smad3 phosphorylation, for Akt or MAPK/ERK in halofuginone-enhanced myotube fusion, a feature which is crucial to improving muscle function in muscular dystrophies.

Regorafenib induces extrinsic and intrinsic apoptosis through inhibition of ERK/NF-κB activation in hepatocellular carcinoma cells.

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Tsai, Jai-Jen; Pan, Po-Jung; Hsu, Fei-Ting

2017-02-01

The aim of the present study was to investigate the role of NF-κB inactivation in regorafenib-induced apoptosis in human hepatocellular carcinoma SK-HEP-1 cells. SK-HEP-1 cells were treated with different concentrations of the NF-κB inhibitor 4-N-[2-(4-phenoxyphenyl)ethyl]quinazoline-4,6-diamine (QNZ) or regorafenib for different periods. The effects of QNZ and regorafenib on cell viability, expression of NF-κB-modulated anti-apoptotic proteins and apoptotic pathways were analyzed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, western blotting, DNA gel electrophoresis, flow cytometry and NF-κB reporter gene assay. Inhibitors of various kinases including AKT, c-Jun N-terminal kinase (JNK), P38 and extracellular signal-regulated kinase (ERK) were used to evaluate the mechanism of regorafenib-induced NF-κB inactivation. The results demonstrated that both QNZ and regorafenib significantly inhibited the expression of anti-apoptotic proteins and triggered extrinsic and intrinsic apoptosis. We also demonstrated that regorafenib inhibited NF-κB activation through ERK dephosphorylation. Taken all together, our findings indicate that regorafenib triggers extrinsic and intrinsic apoptosis through suppression of ERK/NF-κB activation in SK-HEP-1 cells.

B-Raf and CRHR1 internalization mediate biphasic ERK1/2 activation by CRH in hippocampal HT22 Cells.

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Bonfiglio, Juan J; Inda, Carolina; Senin, Sergio; Maccarrone, Giuseppina; Refojo, Damián; Giacomini, Damiana; Turck, Christoph W; Holsboer, Florian; Arzt, Eduardo; Silberstein, Susana

2013-03-01

CRH is a key regulator of neuroendocrine, autonomic, and behavioral response to stress. CRH-stimulated CRH receptor 1 (CRHR1) activates ERK1/2 depending on intracellular context. In a previous work, we demonstrated that CRH activates ERK1/2 in limbic areas of the mouse brain (hippocampus and basolateral amygdala). ERK1/2 is an essential mediator of hippocampal physiological processes including emotional behavior, synaptic plasticity, learning, and memory. To elucidate the molecular mechanisms by which CRH activates ERK1/2 in hippocampal neurons, we used the mouse hippocampal cell line HT22. We document for the first time that ERK1/2 activation in response to CRH is biphasic, involving a first cAMP- and B-Raf-dependent early phase and a second phase that critically depends on CRHR1 internalization and β-arrestin2. By means of mass-spectrometry-based screening, we identified B-Raf-associated proteins that coimmunoprecipitate with endogenous B-Raf after CRHR1 activation. Using molecular and pharmacological tools, the functional impact of selected B-Raf partners in CRH-dependent ERK1/2 activation was dissected. These results indicate that 14-3-3 proteins, protein kinase A, and Rap1, are essential for early CRH-induced ERK1/2 activation, whereas dynamin and vimentin are required for the CRHR1 internalization-dependent phase. Both phases of ERK1/2 activation depend on calcium influx and are affected by calcium/calmodulin-dependent protein kinase II inactivation. Thus, this report describes the dynamics and biphasic nature of ERK1/2 activation downstream neuronal CRHR1 and identifies several new critical components of the CRHR1 signaling machinery that selectively controls the early and late phases of ERK1/2 activation, thus providing new potential therapeutic targets for stress-related disorders.

Focused microwave irradiation-assisted immunohistochemistry to study effects of ketamine on phospho-ERK expression in the mouse brain.

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Fernandes, Alda; Li, Yu-Wen

2017-09-01

Ketamine produces rapid and long-lasting antidepressant effects in depressive patients. Preclinical studies demonstrate that ketamine stimulates AMPA receptor transmission and activates BDNF/TrkB-Akt/ERK-mTOR signaling cascades, leading to a sustained increase in synaptic protein synthesis and strengthening of synaptic plasticity, a potential mechanism underlying the antidepressant effects. The purpose of this study was to develop an immunohistochemistry (IHC) assay to map the distribution of extracellular signal-regulated kinase (ERK) phosphorylation in the mouse brain in response to systemic ketamine treatment. We established a focused microwave irradiation-assisted IHC assay to detect phosphorylated (phospho) proteins including phospho-ERK, phospho- cAMP-response- element-binding protein (CREB), phospho- glutamate receptor 1 (GluR1) and phospho- calcium/calmodulin-dependent protein kinase II (CaMKII) with greater sensitivity and reproducibility in comparison to conventional IHC methods. A single dose of ketamine produced a robust, dose- and time-dependent increase in phospho-ERK immunoreactive (phospho-ERK-ir) neurons in the medial prefrontal cortex (mPFC) and the central nucleus of the amygdala. Phospho-ERK-ir neurons in the mPFC were primarily located in the prelimbic and anterior cingulate subregions with the morphology resembling pyramidal neurons. An increase in phospho-ERK-ir was also observed in the brainstem dorsal raphe nucleus and locus coeruleus. The NMDA GluN2B subtype receptor antagonist Ro 25-6981 increased phospho-ERK expression in the brain in a similar pattern as ketamine. In summary, we have established a sensitive and reliable focused microwave irradiation-assisted IHC assay, and defined the activation pattern of ERK, in response to systemic ketamine and Ro 25-6981 treatment, in brain regions that are potentially responsible for mediating the antidepressant effects. Copyright © 2017 Elsevier B.V. All rights reserved.

Regulation of death induction and chemosensitizing action of 3-bromopyruvate in myeloid leukemia cells: energy depletion, oxidative stress, and protein kinase activity modulation.

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Calviño, Eva; Estañ, María Cristina; Sánchez-Martín, Carlos; Brea, Rocío; de Blas, Elena; Boyano-Adánez, María del Carmen; Rial, Eduardo; Aller, Patricio

2014-02-01

3-Bromopyruvate (3-BrP) is an alkylating, energy-depleting drug that is of interest in antitumor therapies, although the mechanisms underlying its cytotoxicity are ill-defined. We show here that 3-BrP causes concentration-dependent cell death of HL60 and other human myeloid leukemia cells, inducing both apoptosis and necrosis at 20-30 μM and a pure necrotic response at 60 μM. Low concentrations of 3-BrP (10-20 μM) brought about a rapid inhibition of glycolysis, which at higher concentrations was followed by the inhibition of mitochondrial respiration. The combination of these effects causes concentration-dependent ATP depletion, although this cannot explain the lethality at intermediate 3-BrP concentrations (20-30 μM). The oxidative stress caused by exposure to 3-BrP was evident as a moderate overproduction of reactive oxygen species and a concentration-dependent depletion of glutathione, which was an important determinant of 3-BrP toxicity. In addition, 3-BrP caused glutathione-dependent stimulation of p38 mitogen-activated protein kinase (MAPK), mitogen-induced extracellular kinase (MEK)/extracellular signal-regulated kinase (ERK), and protein kinase B (Akt)/mammalian target of rapamycin/p70S6K phosphorylation or activation, as well as rapid LKB-1/AMP kinase (AMPK) activation, which was later followed by Akt-mediated inactivation. Experiments with pharmacological inhibitors revealed that p38 MAPK activation enhances 3-BrP toxicity, which is conversely restrained by ERK and Akt activity. Finally, 3-BrP was seen to cooperate with antitumor agents like arsenic trioxide and curcumin in causing cell death, a response apparently mediated by both the generation of oxidative stress induced by 3-BrP and the attenuation of Akt and ERK activation by curcumin. In summary, 3-BrP cytotoxicity is the result of several combined regulatory mechanisms that might represent important targets to improve therapeutic efficacy.

Shoc2 is targeted to late endosomes and required for Erk1/2 activation in EGF-stimulated cells.

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Emilia Galperin

Full Text Available Shoc2 is the putative scaffold protein that interacts with RAS and RAF, and positively regulates signaling to extracellular signal-regulated protein kinases 1 and 2 (ERK1/2. To elucidate the mechanism by which Shoc2 regulates ERK1/2 activation by the epidermal growth factor (EGF receptor (EGFR, we studied subcellular localization of Shoc2. Upon EGFR activation, endogenous Shoc2 and red fluorescent protein tagged Shoc2 were translocated from the cytosol to a subset of late endosomes containing Rab7. The endosomal recruitment of Shoc2 was blocked by overexpression of a GDP-bound H-RAS (N17S mutant and RNAi knockdown of clathrin, suggesting the requirement of RAS activity and clathrin-dependent endocytosis. RNAi depletion of Shoc2 strongly inhibited activation of ERK1/2 by low, physiological EGF concentrations, which was rescued by expression of wild-type recombinant Shoc2. In contrast, the Shoc2 (S2G mutant, that is myristoylated and found in patients with the Noonan-like syndrome, did not rescue ERK1/2 activation in Shoc2-depleted cells. Shoc2 (S2G was not located in late endosomes but was present on the plasma membrane and early endosomes. These data suggest that targeting of Shoc2 to late endosomes may facilitate EGFR-induced ERK activation under physiological conditions of cell stimulation by EGF, and therefore, may be involved in the spatiotemporal regulation of signaling through the RAS-RAF module.

Hydrogen sulfide potentiates interleukin-1β-induced nitric oxide production via enhancement of extracellular signal-regulated kinase activation in rat vascular smooth muscle cells

International Nuclear Information System (INIS)

Jeong, Sun-Oh; Pae, Hyun-Ock; Oh, Gi-Su; Jeong, Gil-Saeng; Lee, Bok-Soo; Lee, Seoul; Kim, Du Yong; Rhew, Hyun Yul; Lee, Kang-Min; Chung, Hun-Taeg

2006-01-01

Hydrogen sulfide (H 2 S) and nitric oxide (NO) are endogenously synthesized from L-cysteine and L-arginine, respectively. They might constitute a cooperative network to regulate their effects. In this study, we investigated whether H 2 S could affect NO production in rat vascular smooth muscle cells (VSMCs) stimulated with interleukin-1β (IL-1β). Although H 2 S by itself showed no effect on NO production, it augmented IL-β-induced NO production and this effect was associated with increased expression of inducible NO synthase (iNOS) and activation of nuclear factor (NF)-κB. IL-1β activated the extracellular signal-regulated kinase 1/2 (ERK1/2), and this activation was also enhanced by H 2 S. Inhibition of ERK1/2 activation by the selective inhibitor U0126 inhibited IL-1β-induced NF-κB activation, iNOS expression, and NO production either in the absence or presence of H 2 S. Our findings suggest that H 2 S enhances NO production and iNOS expression by potentiating IL-1β-induced NF-κB activation through a mechanism involving ERK1/2 signaling cascade in rat VSMCs

Agmatine Protects Against 6-OHDA-Induced Apoptosis, and ERK and Akt/GSK Disruption in SH-SY5Y Cells.

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Amiri, Esmat; Ghasemi, Rasoul; Moosavi, Maryam

2016-08-01

6-Hydroxydopamine (6-OHDA), a metabolite of dopamine is known to induce dopaminergic cell toxicity which makes that a suitable agent inducing an experimental model of Parkinson's disease (PD). Agmatine has been shown to protect against some cellular and animal PD models. This study was aimed to assess whether agmatine prevents 6-OHDA-induced SH-SY5Y cell death and if yes, then how it affects Akt/glycogen synthesis kinase-3β (GSK-3β) and extracellular signal-regulated kinases (ERK) signals. The cells were treated with different drugs, and their viability was examined via MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay and morphological observation. Western blot studies were done to assess cleaved caspase-3, Akt/GSK-3β, and ERK proteins. 6-OHDA-induced cell death and caspase-3 cleavage, while agmatine prevented those changes. 6-OHDA also decreased the amount of phosphorylated Akt (pAkt)/Akt while increased GSK-3β activity which was prevented by agmatine. Additionally, this toxin increased pERK/ERK ratio which was averted again by agmatine. The PI3/Akt inhibitor, LY294002, impeded the changes induced by agmatine, while ERK inhibitor (PD98059) did not disturb the effects of agmatine, and by itself, it preserved the cells against 6-OHDA toxicity. This study revealed that agmatine is protective in 6-OHDA model of PD and affects Akt/GSK-3β and ERK pathways.

CTGF enhances resistance to 5-FU-mediating cell apoptosis through FAK/MEK/ERK signal pathway in colorectal cancer

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Yang K

2016-11-01

Full Text Available Kai Yang, Kai Gao, Gui Hu, Yanguang Wen, Changwei Lin, Xiaorong Li Department of General Surgery, The Third Affiliated Hospital of Central South University, Central South University, Changsha, Hunan, People’s Republic of China Abstract: Colorectal cancer (CRC is one of the most commonly diagnosed cancers among both males and females; the chemotherapy drug 5-fluorouracil (5-FU is one of a doctors’ first lines of defense against CRC. However, therapeutic failures are common because of the emergence of drug resistance. Connective tissue growth factor (CTGF is a secreted protein that binds to integrins, and regulates the invasiveness and metastasis of certain carcinoma cells. Here, we found that CTGF was upregulated in drug-resistant phenotype of human CRC cells. Overexpression of CTGF enhanced the resistance to 5-FU-induced cell apoptosis. Moreover, downregulating the expression of CTGF promoted the curative effect of chemotherapy and blocked the cell cycle in the G1 phase. We also found that CTGF facilitated resistance to 5-FU-induced apoptosis by increasing the expression of B-cell lymphoma-extra large (Bcl-xL and survivin. Then we pharmacologically blocked MEK/ERK signal pathway and assessed 5-FU response by MTT assays. Our current results indicate that the expression of phosphorylated forms of MEK/ERK increased in high CTGF expression cells and MEK inhibited increases in 5-FU-mediated apoptosis of resistant CRC cells. Therefore, our data suggest that MEK/ERK signaling contributes to 5-FU resistance through upstream of CTGF, and supports CRC cell growth. Comprehending the molecular mechanism underlying 5-FU resistance may ultimately aid the fight against CRC. Keywords: connective tissue growth factor, 5-fluorouracil, mitogen-activated protein kinase/extracellular regulated protein kinases, phosphatidyl inositol 3-kinase/serine/threonine kinase Akt, colorectal cancer

8-O-Acetyl Shanzhiside Methylester From Lamiophlomis Rotata Reduces Neuropathic Pain by Inhibiting the ERK/TNF-α Pathway in Spinal Astrocytes

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Wei Zhang

2018-03-01

Full Text Available Lamiophlomis rotata (L. rotata; Benth. Kudo is an effective traditional herb in the clinical treatment of chronic pain syndromes in China. 8-O-acetyl shanzhiside methylester (8-OaS, a chief component in L. rotata, possesses potent immunosuppressive activities and favorable analgesic effects. This study was proposed to compare the analgesic effects of 8-OaS with those of lidocaine and ketamine in a spinal nerve ligation (SNL model by behavioral tests, and then investigated its effects upon the expression of spinal glial fibrillary acidic protein (GFAP, phosphorylated extracellular regulated protein kinases (pERK and tumor necrosis factor-alpha (TNF-α via immunofluorescence staining and western blot analyses. The data showed consecutive intrathecal injection of 8-OaS for 2 weeks brought about remarkable palliation of neuropathic pain (NP, possessing similar anti-allodynia effects with those of lidocaine and ketamine. Two weeks after surgery, pERK within the spinal dorsal horn was mainly expressed in astrocytes more than neurons and microglia, and 8-OaS inhibited spinal astrocytic activation and TNF-α expression. Finally, co-treatment of 8-OaS and PD98059 (an Extracellular signal-regulated kinase, ERK inhibitor did not lead to remarkable increase in pain relief or TNF-α expression comparing to rats treated with 8-OaS or PD98059 alone. In conclusion, the anti-nociceptive effects of 8-OaS in the condition of NP relied on the inhibition of SNL-induced astrocyte activation, probably via the down-regulation of the ERK/TNF-α pathway.

Cell-type-specific activation of mitogen-activated protein kinases in PAN-induced progressive renal disease in rats

International Nuclear Information System (INIS)

Park, Sang-Joon; Jeong, Kyu-Shik

2004-01-01

We examined the time-course activation and the cell-type specific role of MAP kinases in puromycin aminonucleoside (PAN)-induced renal disease. The maximal activation of c-Jun-NH 2 -terminal kinase (JNK), extracellular signal regulated kinase (ERK), and p38 MAP kinase was detected on Days 52, 38, and 38 after PAN-treatment, respectively. p-JNK was localized in mesangial and proximal tubular cells at the early renal injury. It was expressed, therefore, in the inflammatory cells of tubulointerstitial lesions. While, p-ERK was markedly increased in the glomerular regions and macrophages p-p38 was observed in glomerular endothelial cells, tubular cells, and some inflammatory cells. The results show that the activation of MAP kinases in the early renal injury by PAN-treatment involves cellular changes such as cell proliferation or apoptosis in renal native cells. The activation of MAP kinases in infiltrated inflammatory cells and fibrotic cells plays an important role in destructive events such as glomerulosclerosis and tubulointerstitial fibrosis

c-Met Overexpression Contributes to the Acquired Apoptotic Resistance of Nonadherent Ovarian Cancer Cells through a Cross Talk Mediated by Phosphatidylinositol 3-Kinase and Extracellular Signal-Regulated Kinase 1/2

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Maggie K.S. Tang

2010-02-01

Full Text Available Ovarian cancer is the most lethal gynecologic cancer mainly because of widespread peritoneal dissemination and malignant ascites. Key to this is the capacity of tumor cells to escape suspension-induced apoptosis (anoikis, which also underlies their resistance to chemotherapy. Here, we used a nonadherent cell culture model to investigate the molecular mechanisms of apoptotic resistance of ovarian cancer cells that may mimic the chemoresistance found in solid tumors. We found that ovarian cancer cells acquired a remarkable resistance to anoikis and apoptosis induced by exposure to clinically relevant doses of two front-line chemotherapeutic drugs cisplatin and paclitaxel when grown in three-dimensional than monolayer cultures. Inhibition of the hepatocyte growth factor (HGF receptor c-Met, which is frequently overexpressed in ovarian cancer, by a specific inhibitor or small interfering RNA blocked the acquired anoikis resistance and restored chemosensitivity in three-dimensional not in two-dimensional cultures. These effects were found to be dependent on both phosphatidylinositol 3-kinase (PI3K/Akt and extracellular signal-regulated kinase (ERK 1/2 signaling pathways. Inhibitors of PI3K/Akt abrogated ERK1/2 activation and its associated anoikis resistance in response to HGF, suggesting a signaling relay between these two pathways. Furthermore, we identified a central role of Ras as a mechanism of this cross talk. Interestingly, Ras did not lie upstream of PI3K/Akt, whereas PI3K/Akt signaling to ERK1/2 involved Ras. These findings shed new light on the apoptotic resistance mechanism of nonadherent ovarian cancer ascites cells and may have important clinical implications.

Effects of electroacupuncture on the cortical extracellular signal regulated kinase pathway in rats with cerebral ischaemia/reperfusion.

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Wu, Chunxiao; Li, Chun; Zhou, Guoping; Yang, Lu; Jiang, Guimei; Chen, Jing; Li, Qiushi; Zhan, Zhulian; Xu, Xiuhong; Zhang, Xin

2017-12-01

To explore the effects of electroacupuncture (EA) on the phosphorylated extracellular signal regulated kinase (p-ERK) pathway of the cerebral cortex in a rat model of focal cerebral ischaemia/reperfusion (I/R). 160 adult Sprague-Dawley rats underwent middle carotid artery occlusion (MCAO) to establish I/R injury and were randomly divided into four groups (n=40 each) that remained untreated (I/R group) or received EA at LU5, LI4, ST36 and SP6 (I/R+EA group), the ERK inhibitor PD98059 (I/R+PD group), or both interventions (I/R+PD+EA groups). An additional 40 rats undergoing sham surgery formed a healthy control group. Eight rats from each group were sacrificed at the following time points: 2 hours, 6 hours, 1 day, 3 days and 1 week. Neurological function was assessed using neurological deficit scores, morphological examination was performed following haematoxylin-eosin staining of cortical tissues, and apoptotic indices were calculated after terminal deoxyribonucleotidyl transferase (TdT)-mediated biotin-16-dUTP nick-end labelling. Cortical protein and mRNA expression of p-ERK and ERK were measured by immunohistochemistry and real-time quantitative PCR, respectively. Compared with the I/R group, neurological deficit scores and apoptotic indices were lower in the I/R+EA group at 1 and 3 days, whereas mRNA/protein expression of ERK/p-ERK was higher in the EA group at all time points studied. Our results suggest that EA can alleviate neurological deficits and reduce cortical apoptosis in rats with I/R injury. These anti-apoptotic effects may be due to upregulation of p-ERK. Moreover, apoptosis appeared to peak at 1 day after I/R injury, which might therefore represent the optimal time point for targeting of EA. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Blockades of mitogen-activated protein kinase and calcineurin both change fibre-type markers in skeletal muscle culture

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Higginson, James; Wackerhage, Henning; Woods, Niall

2002-01-01

A and mitogen-activated protein kinase kinase (MEK1/2) blockade with U0126 upon myosin heavy chain (MHC) isoform mRNA levels and activities of metabolic enzymes after 1 day, 3 days and 7 days of treatment in primary cultures of spontaneously twitching rat skeletal muscle. U0126 treatment significantly decreased......Activation of either the calcineurin or the extracellular signal-regulated kinase (ERK1/2) pathway increases the percentage of slow fibres in vivo suggesting that both pathways can regulate fibre phenotypes in skeletal muscle. We investigated the effect of calcineurin blockade with cyclosporin...

Structural and functional characterization of the recombinant death domain from death-associated protein kinase.

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Dioletis, Evangelos; Dingley, Andrew J; Driscoll, Paul C

2013-01-01

Death-associated protein kinase (DAPk) is a calcium/calmodulin-regulated Ser/Thr-protein kinase that functions at an important point of integration for cell death signaling pathways. DAPk has a structurally unique multi-domain architecture, including a C-terminally positioned death domain (DD) that is a positive regulator of DAPk activity. In this study, recombinant DAPk-DD was observed to aggregate readily and could not be prepared in sufficient yield for structural analysis. However, DAPk-DD could be obtained as a soluble protein in the form of a translational fusion protein with the B1 domain of streptococcal protein G. In contrast to other DDs that adopt the canonical six amphipathic α-helices arranged in a compact fold, the DAPk-DD was found to possess surprisingly low regular secondary structure content and an absence of a stable globular fold, as determined by circular dichroism (CD), NMR spectroscopy and a temperature-dependent fluorescence assay. Furthermore, we measured the in vitro interaction between extracellular-regulated kinase-2 (ERK2) and various recombinant DAPk-DD constructs. Despite the low level of structural order, the recombinant DAPk-DD retained the ability to interact with ERK2 in a 1∶1 ratio with a K d in the low micromolar range. Only the full-length DAPk-DD could bind ERK2, indicating that the apparent 'D-motif' located in the putative sixth helix of DAPk-DD is not sufficient for ERK2 recognition. CD analysis revealed that binding of DAPk-DD to ERK2 is not accompanied by a significant change in secondary structure. Taken together our data argue that the DAPk-DD, when expressed in isolation, does not adopt a classical DD fold, yet in this state retains the capacity to interact with at least one of its binding partners. The lack of a stable globular structure for the DAPk-DD may reflect either that its folding would be supported by interactions absent in our experimental set-up, or a limitation in the structural bioinformatics

HSF1 phosphorylation by ERK/GSK3 suppresses RNF126 to sustain IGF-IIR expression for hypertension-induced cardiomyocyte hypertrophy.

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Huang, Chih-Yang; Lee, Fa-Lun; Peng, Shu-Fen; Lin, Kuan-Ho; Chen, Ray-Jade; Ho, Tsung-Jung; Tsai, Fu-Jen; Padma, Vijaya V; Kuo, Wei-Wen; Huang, Chih-Yang

2018-02-01

Hypertension-induced cardiac hypertrophy and apoptosis are major characteristics of early-stage heart failure (HF). Inhibition of extracellular signal-regulated kinases (ERK) efficaciously suppressed angiotensin II (ANG II)-induced cardiomyocyte hypertrophy and apoptosis by blocking insulin-like growth factor II receptor (IGF-IIR) signaling. However, the detailed mechanism by which ANG II induces ERK-mediated IGF-IIR signaling remains elusive. Here, we found that ANG II activated ERK to upregulate IGF-IIR expression via the angiotensin II type I receptor (AT 1 R). ERK activation subsequently phosphorylates HSF1 at serine 307, leading to a secondary phosphorylation by glycogen synthase kinase III (GSK3) at serine 303. Moreover, we found that ANG II mediated ERK/GSK3-induced IGF-IIR protein stability by downregulating the E3 ubiquitin ligase of IGF-IIR RING finger protein CXXVI (RNF126). The expression of RNF126 decreased following ANG II-induced HSF1 S303 phosphorylation, resulting in IGF-IIR protein stability and increased cardiomyocyte injury. Inhibition of GSK3 significantly alleviated ANG II-induced cardiac hypertrophy in vivo and in vitro. Taken together, these results suggest that HSF1 phosphorylation stabilizes IGF-IIR protein stability by downregulating RNF126 during cardiac hypertrophy. ANG II activates ERK/GSK3 to phosphorylate HSF1, resulting in RNF126 degradation, which stabilizes IGF-IIR protein expression and eventually results in cardiac hypertrophy. HSF1 could be a valuable therapeutic target for cardiac diseases among hypertensive patients. © 2017 Wiley Periodicals, Inc.

Protective function of pyridoxamine on retinal photoreceptor cells via activation of the p‑Erk1/2/Nrf2/Trx/ASK1 signalling pathway in diabetic mice.

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Ren, Xiang; Sun, Hong; Zhang, Chenghong; Li, Chen; Wang, Jinlei; Shen, Jie; Yu, Dong; Kong, Li

2016-07-01

The present study aimed to investigate the mechanisms that mediate the protective effects of pyridoxamine (PM) on light‑damaged retinal photoreceptor cells in diabetic mice. A high‑fat diet and streptozotocin were used to induce a mouse model of type II diabetes. During the experiment, mice were divided the mice into three types of group, as follows: Control groups (negative control and light‑damaged groups); experimental groups (diabetic and diabetic light‑damaged groups); and treatment groups (25, 50 and 100 mg/kg PM‑treated groups). Using hematoxylin‑eosin staining, the number of nuclear layer cells were counted. Western blotting and immunohistochemistry were performed to measure the levels of thioredoxin (Trx), phospho‑extracellular signal‑regulated kinase 1/2 (p‑Erk1/2), nuclear factor erythroid 2‑related factor 2 (Nrf2) and apoptosis signal‑regulating kinase 1 (ASK1). The photoreceptor cell count in the outer nuclear layer of the light‑damaged, diabetic control and diabetic light‑damaged groups were significantly reduced compared with the negative control group (PTrx, p‑Erk1/2 and Nrf2 expression levels (PTrx, p‑Erk1/2 and Nrf2 expression levels were significantly increased (PTrx, p‑Erk1/2 and Nrf2 expression, and the downregulation of ASK1 expression.

Biglycan- and Sphingosine Kinase-1 Signaling Crosstalk Regulates the Synthesis of Macrophage Chemoattractants

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Louise Tzung-Harn Hsieh

2017-03-01

Full Text Available In its soluble form, the extracellular matrix proteoglycan biglycan triggers the synthesis of the macrophage chemoattractants, chemokine (C-C motif ligand CCL2 and CCL5 through selective utilization of Toll-like receptors (TLRs and their adaptor molecules. However, the respective downstream signaling events resulting in biglycan-induced CCL2 and CCL5 production have not yet been defined. Here, we show that biglycan stimulates the production and activation of sphingosine kinase 1 (SphK1 in a TLR4- and Toll/interleukin (IL-1R domain-containing adaptor inducing interferon (IFN-β (TRIF-dependent manner in murine primary macrophages. We provide genetic and pharmacological proof that SphK1 is a crucial downstream mediator of biglycan-triggered CCL2 and CCL5 mRNA and protein expression. This is selectively driven by biglycan/SphK1-dependent phosphorylation of the nuclear factor NF-κB p65 subunit, extracellular signal-regulated kinase (Erk1/2 and p38 mitogen-activated protein kinases. Importantly, in vivo overexpression of soluble biglycan causes Sphk1-dependent enhancement of renal CCL2 and CCL5 and macrophage recruitment into the kidney. Our findings describe the crosstalk between biglycan- and SphK1-driven extracellular matrix- and lipid-signaling. Thus, SphK1 may represent a new target for therapeutic intervention in biglycan-evoked inflammatory conditions.

8-C-(E-phenylethenyl)quercetin from onion/beef soup induces autophagic cell death in colon cancer cells through ERK activation.

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Zhao, Yueliang; Fan, Daming; Zheng, Zong-Ping; Li, Edmund T S; Chen, Feng; Cheng, Ka-Wing; Wang, Mingfu

2017-02-01

Quercetin, a flavonoid, widely distributed in edible fruits and vegetables, was reported to effectively inhibit 2-amino-1-methyl-6-phenylimidazo[4, 5-b]pyridine (PhIP) formation in a food model (roast beef patties) with itself being converted into a novel compound 8-C-(E-phenylethenyl)quercetin (8-CEPQ). Here we investigated whether 8-CEPQ could be formed in a real food system, and tested its anticancer activity in human colon cancer cell lines. LC-MS was applied for the determination of 8-CEPQ formation in onion/beef soup. Anticancer activity of 8-CEPQ was evaluated by using cell viability assay and flow cytometry. Results showed that 8-CEPQ suppressed proliferation and caused G 2 phase arrest in colon cancer cells. Based on immunofluorescent staining assay, western blot assay, and RNA knockdown data, we found that 8-CEPQ did not cause apoptotic cell death. Instead, it induced autophagic cell death. Moreover, treatment with 8-CEPQ induced phosphorylation of extracellular signal-regulated kinase (ERK). Inhibition of ERK phosphorylation by the mitogen-activated protein kinase kinase (MEK)/ERK inhibitor U0126 attenuated 8-CEPQ-induced autophagy and reversed 8-CEPQ-mediated cell growth inhibition. Our results demonstrate that 8-CEPQ, a novel quercetin derivative, could be formed in onion/beef soup. 8-CEPQ inhibited colon cancer cell growth by inducing autophagic cell death through ERK activation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fps/Fes protein-tyrosine kinase regulates mast cell adhesion and migration downstream of Kit and beta1 integrin receptors.

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Smith, Julie A; Samayawardhena, Lionel A; Craig, Andrew W B

2010-03-01

Activation of Kit receptor protein-tyrosine kinase (PTK) by its ligand Stem Cell Factor (SCF) is required for the development of mast cells, and for the regulation of mast cell proliferation, migration and modulation of inflammatory mediator release. Recent studies have implicated the non-receptor PTK Fps/Fes (hereafter referred to as Fes) in signaling downstream of oncogenic Kit, however, the potential role of Fes in regulating Kit signaling is not well defined. In this study, we show that SCF induces transient tyrosine phosphorylation of wild-type Fes as well as kinase-dead Fes in bone marrow-derived mast cells (BMMCs). The latter finding implicates an upstream kinase acting on Fes, which we identified as Fyn PTK. SCF treatment of BMMCs promoted recruitment of Fes to Kit, potentially via direct interaction of the Fes SH2 domain with phosphorylated Kit. While Fes was not required for SCF-induced signaling to Akt and Erk kinases, Fes-deficient (fes-/-) BMMCs displayed a defect in sustained p38 kinase activation, compared to control cells. SCF-treated Fes-deficient BMMCs also displayed elevated beta1 integrin-mediated cell adhesion and spreading on fibronectin, compared to control cells, and a reduction in cell polarization at later times of SCF treatment. Restoring Fes expression in fes-/- BMMCs by retroviral transduction was sufficient to rescue cell spreading and polarization defects. Interestingly, SCF-induced chemotaxis of BMMCs was also defective in Fes-deficient BMMCs, and restored in Fes-rescue BMMCs. Overall, these results implicate Fes in regulating cross-talk between Kit and beta1 integrins to promote cytoskeletal reorganization and motility of mast cells.

Association between GRB2/Sos and insulin receptor substrate 1 is not sufficient for activation of extracellular signal-regulated kinases by interleukin-4: implications for Ras activation by insulin.

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Pruett, W; Yuan, Y; Rose, E; Batzer, A G; Harada, N; Skolnik, E Y

1995-03-01

Insulin receptor substrate 1 (IRS-1) mediates the activation of a variety of signaling pathways by the insulin and insulin-like growth factor 1 receptors by serving as a docking protein for signaling molecules with SH2 domains. We and others have shown that in response to insulin stimulation IRS-1 binds GRB2/Sos and have proposed that this interaction is important in mediating Ras activation by the insulin receptor. Recently, it has been shown that the interleukin (IL)-4 receptor also phosphorylates IRS-1 and an IRS-1-related molecule, 4PS. Unlike insulin, however, IL-4 fails to activate Ras, extracellular signal-regulated kinases (ERKs), or mitogen-activated protein kinases. We have reconstituted the IL-4 receptor into an insulin-responsive L6 myoblast cell line and have shown that IRS-1 is tyrosine phosphorylated to similar degrees in response to insulin and IL-4 stimulation in this cell line. In agreement with previous findings, IL-4 failed to activate the ERKs in this cell line or to stimulate DNA synthesis, whereas the same responses were activated by insulin. Surprisingly, IL-4's failure to activate ERKs was not due to a failure to stimulate the association of tyrosine-phosphorylated IRS-1 with GRB2/Sos; the amounts of GRB2/Sos associated with IRS-1 were similar in insulin- and IL-4-stimulated cells. Moreover, the amounts of phosphatidylinositol 3-kinase activity associated with IRS-1 were similar in insulin- and IL-4-stimulated cells. In contrast to insulin, however, IL-4 failed to induce tyrosine phosphorylation of Shc or association of Shc with GRB2. Thus, ERK activation correlates with Shc tyrosine phosphorylation and formation of an Shc/GRB2 complex. Thus, ERK activation correlates with Shc tyrosine phosphorylation and formation of an Shc/GRB2 complex. Previous studies have indicated that activation of ERks in this cell line is dependent upon Ras since a dominant-negative Ras (Asn-17) blocks ERK activation by insulin. Our findings, taken in the context

PTK6 promotes cancer migration and invasion in pancreatic cancer cells dependent on ERK signaling.

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Hiroaki Ono

Full Text Available Protein Tyrosine Kinase 6 (PTK6 is a non-receptor type tyrosine kinase that may be involved in some cancers. However, the biological role and expression status of PTK6 in pancreatic cancer is unknown. Therefore in this study, we evaluated the functional role of PTK6 on pancreatic cancer invasion. Five pancreatic cancer cell lines expressed PTK6 at varying levels. PTK6 expression was also observed in human pancreatic adenocarcinomas. PTK6 suppression by siRNA significantly reduced both cellular migration and invasion (0.59/0.49 fold for BxPC3, 0.61/0.62 for Panc1, 0.42/0.39 for MIAPaCa2, respectively, p<0.05 for each. In contrast, forced overexpression of PTK6 by transfection of a PTK6 expression vector in Panc1 and MIAPaCa2 cells increased cellular migration and invasion (1.57/1.67 fold for Panc1, 1.44/1.57 for MIAPaCa2, respectively, p<0.05. Silencing PTK6 reduced ERK1/2 activation, but not AKT or STAT3 activation, while PTK6 overexpression increased ERK1/2 activation. U0126, a specific inhibitor of ERK1/2, completely abolished the effect of PTK6 overexpression on cellular migration and invasion. These results suggest that PTK6 regulates cellular migration and invasion in pancreatic cancer via ERK signaling. PTK6 may be a novel therapeutic target for pancreatic cancer.

Mixed lineage kinase 3 is required for matrix metalloproteinase expression and invasion in ovarian cancer cells

International Nuclear Information System (INIS)

Zhan, Yu; Abi Saab, Widian F.; Modi, Nidhi; Stewart, Amanda M.; Liu, Jinsong; Chadee, Deborah N.

2012-01-01

Mixed lineage kinase 3 (MLK3) is a mitogen-activated protein kinase kinase kinase (MAP3K) that activates MAPK signaling pathways and regulates cellular responses such as proliferation, migration and apoptosis. Here we report high levels of total and phospho-MLK3 in ovarian cancer cell lines in comparison to immortalized nontumorigenic ovarian epithelial cell lines. Using small interfering RNA (siRNA)-mediated gene silencing, we determined that MLK3 is required for the invasion of SKOV3 and HEY1B ovarian cancer cells. Furthermore, mlk3 silencing substantially reduced matrix metalloproteinase (MMP)-1, -2, -9 and -12 gene expression and MMP-2 and -9 activities in SKOV3 and HEY1B ovarian cancer cells. MMP-1, -2, -9 and-12 expression, and MLK3-induced activation of MMP-2 and MMP-9 requires both extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) activities. In addition, inhibition of activator protein-1 (AP-1) reduced MMP-1, MMP-9 and MMP-12 gene expression. Collectively, these findings establish MLK3 as an important regulator of MMP expression and invasion in ovarian cancer cells. -- Highlights: ► Ovarian cancer cell lines have high levels of total and phosphorylated MLK3. ► MLK3 is required for MMP expression and activity in ovarian cancer cells. ► MLK3 is required for invasion of SKOV3 and HEY1B ovarian cancer cells. ► MLK3-dependent regulation of MMP-2 and MMP-9 activities requires ERK and JNK.

Comparison of MEK/ERK pathway inhibitors on the upregulation of vascular G-protein coupled receptors in rat cerebral arteries

DEFF Research Database (Denmark)

Sandhu, Hardip; Ansar, Saema; Edvinsson, Lars

2010-01-01

on translational level and increased respective contractions. The prostanoid TP receptor mediated contraction curve was left-wards shifted by organ culture. Organ culture was associated with elevated pERK1/2 in the vascular smooth muscle cells: the MEK1/2 inhibitor U0126 attenuated the endothelin ET(B) receptor......Organ culture is an in vitro method for investigating cellular mechanisms involved in upregulation of vasocontractile G-protein coupled receptors. We hypothesize that mitogen-activated-protein kinase (MEK) and/or extracellular-signal-regulated kinase (ERK) specific inhibitors will attenuate the G......), prostanoid TP receptor, and angiotensin II receptor type 1 and type 2 were investigated. Results were verified by measurement of mRNA with real time PCR and by protein immunohistochemistry. Organ culture induced transcriptional upregulation of endothelin ET(B) receptor and of serotonin 5-HT(1B) receptor...

The Insect Neuropeptide PTTH Activates Receptor Tyrosine Kinase Torso to Initiate Metamorphosis

DEFF Research Database (Denmark)

Rewitz, Kim; Yamanaka, Naoki; Gilbert, Lawrence

2009-01-01

Holometabolous insects undergo complete metamorphosis to become sexually mature adults. Metamorphosis is initiated by brain-derived prothoracicotropic hormone (PTTH), which stimulates the production of the molting hormone ecdysone via an incompletely defined signaling pathway. Here we demonstrate...... in the prothoracic gland (PG), and its loss phenocopies the removal of PTTH. The activation of Torso by PTTH stimulates extracellular signal–regulated kinase (ERK) phosphorylation, and the loss of ERK in the PG phenocopies the loss of PTTH and Torso. We conclude that PTTH initiates metamorphosis by activation...

Arctigenin exerts protective effects against myocardial infarction via regulation of iNOS, COX‑2, ERK1/2 and HO‑1 in rats.

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Zhang, Yanmin; Yang, Yong

2018-03-01

The present study aimed to determine the protective effects of arctigenin against myocardial infarction (MI), and its effects on oxidative stress and inflammation in rats. Left anterior coronary arteries of Sprague‑Dawley rats were ligated, in order to generate an acute MI (AMI) model. Arctigenin was administered to AMI rats at 0, 50, 100 or 200 µmol/kg. Western blotting and ELISAs were performed to analyze protein expression and enzyme activity. Arctigenin was demonstrated to effectively inhibit the levels of alanine transaminase, creatine kinase‑MB and lactate dehydrogenase, and to reduce infarct size in AMI rats. In addition, the activity levels of malondialdehyde, interleukin (IL)‑1β and IL‑6 were significantly suppressed, and the levels of glutathione peroxidase, catalase and superoxide dismutase were significantly increased by arctigenin treatment. Arctigenin treatment also suppressed the protein expression levels of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX‑2) and heme oxygenase 1 (HO‑1), and increased the protein expression levels of phosphorylated‑extracellular signal‑regulated kinase 1/2 (p‑ERK1/2) in AMI rats. Overall, the results of the present study suggest that arctigenin may inhibit MI, and exhibits antioxidative and anti‑inflammatory effects through regulation of the iNOS, COX‑2, ERK1/2 and HO‑1 pathways in a rat model of AMI.

Hydrostatic Compress Force Enhances the Viability and Decreases the Apoptosis of Condylar Chondrocytes through Integrin-FAK-ERK/PI3K Pathway

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Ma, Dandan; Kou, Xiaoxing; Jin, Jing; Xu, Taotao; Wu, Mengjie; Deng, Liquan; Fu, Lusi; Liu, Yi; Wu, Gang; Lu, Haiping

2016-01-01

Reduced mechanical stimuli in many pathological cases, such as hemimastication and limited masticatory movements, can significantly affect the metabolic activity of mandibular condylar chondrocytes and the growth of mandibles. However, the molecular mechanisms for these phenomena remain unclear. In this study, we hypothesized that integrin-focal adhesion kinase (FAK)-ERK (extracellular signal–regulated kinase)/PI3K (phosphatidylinositol-3-kinase) signaling pathway mediated the cellular response of condylar chondrocytes to mechanical loading. Primary condylar chondrocytes were exposed to hydrostatic compressive forces (HCFs) of different magnitudes (0, 50, 100, 150, 200, and 250 kPa) for 2 h. We measured the viability, morphology, and apoptosis of the chondrocytes with different treatments as well as the gene, protein expression, and phosphorylation of mechanosensitivity-related molecules, such as integrin α2, integrin α5, integrin β1, FAK, ERK, and PI3K. HCFs could significantly increase the viability and surface area of condylar chondrocytes and decrease their apoptosis in a dose-dependent manner. HCF of 250 kPa resulted in a 1.51 ± 0.02-fold increase of cell viability and reduced the ratio of apoptotic cells from 18.10% ± 0.56% to 7.30% ± 1.43%. HCFs could significantly enhance the mRNA and protein expression of integrin α2, integrin α5, and integrin β1 in a dose-dependent manner, but not ERK1, ERK2, or PI3K. Instead, HCF could significantly increase phosphorylation levels of FAK, ERK1/2, and PI3K in a dose-dependent manner. Cilengitide, the potent integrin inhibitor, could dose-dependently block such effects of HCFs. HCFs enhances the viability and decreases the apoptosis of condylar chondrocytes through the integrin-FAK-ERK/PI3K pathway. PMID:27827993

Attenuation of everolimus-induced cytotoxicity by a protective autophagic pathway involving ERK activation in renal cell carcinoma cells

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Zeng, Yizhou; Tian, Xiaofang; Wang, Quan; He, Weiyang; Fan, Jing; Gou, Xin

2018-01-01

Aim The mammalian target of rapamycin (mTOR) pathway is a critical target for cancer treatment and the mTOR inhibitor everolimus (RAD001) has been approved for treatment of renal cell carcinoma (RCC). However, the limited efficacy of RAD001 has led to the development of drug resistance. Autophagy is closely related to cell survival and death, which may be activated under RAD001 stimulation. The aim of the present study was to identify the underlying mechanisms of RAD001 resistance in RCC cells through cytoprotective autophagy involving activation of the extracellular signal-regulated kinase (ERK) pathway. Methods and results: RAD001 strongly induced autophagy of RCC cells in a dose- and time-dependent manner, as confirmed by Western blot analysis. Importantly, suppression of autophagy by the pharmacological inhibitor chloroquine effectively enhanced RAD001-induced apoptotic cytotoxicity, as demonstrated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and Western blot analysis, indicating a cytoprotective role for RAD001-induced autophagy. In addition, as was shown by the MTT assay, flow cytometry, and Western blot analysis, RAD001 robustly activated ERK, but not c-Jun N-terminal kinase and p38. Activation of ERK was inhibited by the pharmacological inhibitor selumetinib (AZD6244), which effectively promoted RAD001-induced cell death. Moreover, employing AZD6244 markedly attenuated RAD001-induced autophagy and enhanced RAD001-induced apoptosis, which play a central role in RAD001-induced cell death. Furthermore, RAD001-induced autophagy is regulated by ERK-mediated phosphorylation of Beclin-1 and B-cell lymphoma 2, as confirmed by Western blot analysis. Conclusion These results suggest that RAD001-induced autophagy involves activation of the ERK, which may impair cytotoxicity of RAD001 in RCC cells. Thus, inhibition of the activation of ERK pathway-mediated autophagy may be useful to overcome chemoresistance to RAD001. PMID:29719377

Hydrogen sulfide protects against chemical hypoxia-induced injury by inhibiting ROS-activated ERK1/2 and p38MAPK signaling pathways in PC12 cells.

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Aiping Lan

Full Text Available Hydrogen sulfide (H(2S has been proposed as a novel neuromodulator and neuroprotective agent. Cobalt chloride (CoCl(2 is a well-known hypoxia mimetic agent. We have demonstrated that H(2S protects against CoCl(2-induced injuries in PC12 cells. However, whether the members of mitogen-activated protein kinases (MAPK, in particular, extracellular signal-regulated kinase1/2(ERK1/2 and p38MAPK are involved in the neuroprotection of H(2S against chemical hypoxia-induced injuries of PC12 cells is not understood. We observed that CoCl(2 induced expression of transcriptional factor hypoxia-inducible factor-1 alpha (HIF-1α, decreased cystathionine-β synthase (CBS, a synthase of H(2S expression, and increased generation of reactive oxygen species (ROS, leading to injuries of the cells, evidenced by decrease in cell viability, dissipation of mitochondrial membrane potential (MMP , caspase-3 activation and apoptosis, which were attenuated by pretreatment with NaHS (a donor of H(2S or N-acetyl-L cystein (NAC, a ROS scavenger. CoCl(2 rapidly activated ERK1/2, p38MAPK and C-Jun N-terminal kinase (JNK. Inhibition of ERK1/2 or p38MAPK or JNK with kinase inhibitors (U0126 or SB203580 or SP600125, respectively or genetic silencing of ERK1/2 or p38MAPK by RNAi (Si-ERK1/2 or Si-p38MAPK significantly prevented CoCl(2-induced injuries. Pretreatment with NaHS or NAC inhibited not only CoCl(2-induced ROS production, but also phosphorylation of ERK1/2 and p38MAPK. Thus, we demonstrated that a concurrent activation of ERK1/2, p38MAPK and JNK participates in CoCl(2-induced injuries and that H(2S protects PC12 cells against chemical hypoxia-induced injuries by inhibition of ROS-activated ERK1/2 and p38MAPK pathways. Our results suggest that inhibitors of ERK1/2, p38MAPK and JNK or antioxidants may be useful for preventing and treating hypoxia-induced neuronal injury.

Fluoxetine increases the activity of the ERK-CREB signal system and alleviates the depressive-like behavior in rats exposed to chronic forced swim stress.

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Qi, Xiaoli; Lin, Wenjuan; Li, Junfa; Li, Huanhuan; Wang, Weiwen; Wang, Donglin; Sun, Meng

2008-08-01

Our previous research indicates that the extracellular signal-regulated kinase (ERK)-cyclic AMP-responsive-element-binding protein (CREB) signal system may be involved in the molecular mechanism of depression. The present study further investigated the effect of antidepressant fluoxetine on the ERK-CREB signal system and the depressive-like behaviors in rats. Fluoxetine was administrated to either naive rats or stressed rats for 21 days. The results showed that chronic forced swim stress induced depressive-like behaviors and decreased the levels of P-ERK2, P-CREB, ERK1/2 and CREB in hippocampus and prefrontal cortex. Fluoxetine alleviated the depressive-like behaviors and reversed the disruptions of the P-ERK2 and P-CREB in stressed rats. Fluoxetine also exerted mood-elevating effect and increased the levels of the P-ERK2 and P-CREB in naive rats. These results suggest that the ERK-CREB signal system may be the targets of the antidepressant action of fluoxetine and participate in the neuronal mechanism of depression.

The PP2C Alphabet is a negative regulator of stress-activated protein kinase signaling in Drosophila.

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Baril, Caroline; Sahmi, Malha; Ashton-Beaucage, Dariel; Stronach, Beth; Therrien, Marc

2009-02-01

The Jun N-terminal kinase and p38 pathways, also known as stress-activated protein kinase (SAPK) pathways, are signaling conduits reiteratively used throughout the development and adult life of metazoans where they play central roles in the control of apoptosis, immune function, and environmental stress responses. We recently identified a Drosophila Ser/Thr phosphatase of the PP2C family, named Alphabet (Alph), which acts as a negative regulator of the Ras/ERK pathway. Here we show that Alph also plays an inhibitory role with respect to Drosophila SAPK signaling during development as well as under stress conditions such as oxidative or genotoxic stresses. Epistasis experiments suggest that Alph acts at a step upstream of the MAPKKs Hep and Lic. Consistent with this interpretation, biochemical experiments identify the upstream MAPKKKs Slpr, Tak1, and Wnd as putative substrates. Together with previous findings, this work identifies Alph as a general attenuator of MAPK signaling in Drosophila.

Dynamics and control of the ERK signaling pathway: Sensitivity, bistability, and oscillations.

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Arkun, Yaman; Yasemi, Mohammadreza

2018-01-01

Cell signaling is the process by which extracellular information is transmitted into the cell to perform useful biological functions. The ERK (extracellular-signal-regulated kinase) signaling controls several cellular processes such as cell growth, proliferation, differentiation and apoptosis. The ERK signaling pathway considered in this work starts with an extracellular stimulus and ends with activated (double phosphorylated) ERK which gets translocated into the nucleus. We model and analyze this complex pathway by decomposing it into three functional subsystems. The first subsystem spans the initial part of the pathway from the extracellular growth factor to the formation of the SOS complex, ShC-Grb2-SOS. The second subsystem includes the activation of Ras which is mediated by the SOS complex. This is followed by the MAPK subsystem (or the Raf-MEK-ERK pathway) which produces the double phosphorylated ERK upon being activated by Ras. Although separate models exist in the literature at the subsystems level, a comprehensive model for the complete system including the important regulatory feedback loops is missing. Our dynamic model combines the existing subsystem models and studies their steady-state and dynamic interactions under feedback. We establish conditions under which bistability and oscillations exist for this important pathway. In particular, we show how the negative and positive feedback loops affect the dynamic characteristics that determine the cellular outcome.

Pancreatic cancer stimulates pancreatic stellate cell proliferation and TIMP-1 production through the MAP kinase pathway

International Nuclear Information System (INIS)

Yoshida, Seiya; Yokota, Tokuyasu; Ujiki, Michael; Ding Xianzhong; Pelham, Carolyn; Adrian, Thomas E.; Talamonti, Mark S.; Bell, Richard H.; Denham, Woody

2004-01-01

Pancreatic adenocarcinoma is characterized by an intense desmoplastic reaction that surrounds the tumor. Pancreatic stellate cells (PSCs) are thought to be responsible for production of this extracellular matrix. When activated, PSCs have a myofibroblast phenotype and produce not only components of the extracellular matrix including collagen, fibronectin, and laminin, but also matrix metalloproteinases and tissue inhibitors of metalloproteinases (TIMPs). Since PSCs are found in the stroma surrounding human pancreatic adenocarcinoma, we postulate that pancreatic cancer could impact PSC proliferation and TIMP-1 production. Rat PSCs were isolated and cultured. Isolated PSCs were exposed to PANC-1 conditioned medium (CM) and proliferation, activation of the mitogen-activated protein (MAP) kinase pathway, and TIMP-1 gene induction were determined. Exposure to PANC-1 CM increased PSC DNA synthesis, cell number, and TIMP-1 mRNA (real-time PCR) as well as activating the extracellular-regulated kinase (ERK) 1/2. Inhibition of ERK 1/2 phosphorylation (U0126) prevented the increases in growth and TIMP-1 expression. PANC-1 CM stimulates PSC proliferation and TIMP-1 through the MAP kinase (ERK 1/2) pathway

Tyr phosphatase-mediated P-ERK inhibition suppresses senescence in EIA + v-raf transformed cells, which, paradoxically, are apoptosis-protected in a MEK-dependent manner.

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De Vitis, Stefania; Sonia Treglia, Antonella; Ulianich, Luca; Turco, Stefano; Terrazzano, Giuseppe; Lombardi, Angela; Miele, Claudia; Garbi, Corrado; Beguinot, Francesco; Di Jeso, Bruno

2011-02-01

Activation of the Ras-Raf-extracellular signal-regulated kinase (ERK) pathway causes not only proliferation and suppression of apoptosis but also the antioncogenic response of senescence. How these contrasting effects are reconciled to achieve cell transformation and cancer formation is poorly understood. In a system of two-step carcinogenesis (dedifferentiated PC EIA, transformed PC EIA-polyoma-middle T [PC EIA + Py] and PC EIA-v-raf [PC EIA + raf] cells], v-raf cooperated with EIA by virtue of a strong prosurvival effect, not elicited by Py-middle T, evident toward serum-deprivation-and H(2)O(2)-induced apoptosis. Apoptosis was detected by DNA fragmentation and annexin V staining. The prosurvival function of v-raf was, in part, mitogen-activated protein kinase/ERK kinase (MEK)-dependent, as shown by pharmacological MEK inhibition. The MEK-dependent antiapoptotic effect of v-raf was exerted despite a lower level of P-ERK1/2 in EIA + raf cells with respect to EIA + Py/EIA cells, which was dependent on a high tyrosine phosphatase activity, as shown by orthovanadate blockade. An ERK1/2 tyrosine phosphatase was likely involved. The high tyrosine phosphatase activity was instrumental to the complete suppression of senescence, detected by β-galactosidase activity, because tyrosine phosphatase blockade induced senescence in EIA + raf but not in EIA + Py cells. High tyrosine phosphatase activity and evasion from senescence were confirmed in an anaplastic thyroid cancer cell line. Therefore, besides EIA, EIA + raf cells suppress senescence through a new mechanism, namely, phosphatase-mediated P-ERK1/2 inhibition, but, paradoxically, retain the oncogenic effects of the Raf-ERK pathway. We propose that the survival effect of Raf is not a function of absolute P-ERK1/2 levels at a given time but is rather dynamically dependent on greater variations after an apoptotic stimulus.

Tyr Phosphatase-Mediated P-ERK Inhibition Suppresses Senescence in EIA + v-raf Transformed Cells, Which, Paradoxically, Are Apoptosis-Protected in a MEK-Dependent Manner

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Stefania De Vitis

2011-02-01

Full Text Available Activation of the Ras-Raf-extracellular signal-regulated kinase (ERK pathway causes not only proliferation and suppression of apoptosis but also the antioncogenic response of senescence. How these contrasting effects are reconciled to achieve cell transformation and cancer formation is poorly understood. In a system of two-step carcinogenesis (dedifferentiated PC EIA, transformed PC EIA-polyoma-middle T [PC EIA + Py] and PC EIA-v-raf [PC EIA + raf] cells], v-raf cooperated with EIA by virtue of a strong prosurvival effect, not elicited by Py-middle T, evident toward serum-deprivation-and H2O2-induced apoptosis. Apoptosis was detected by DNA fragmentation and annexin V staining. The prosurvival function of v-raf was, in part, mitogen-activated protein kinase/ERK kinase (MEK-dependent, as shown by pharmacological MEK inhibition. The MEK-dependent antiapoptotic effect of v-raf was exerted despite a lower level of P-ERK1/2 in EIA + raf cells with respect to EIA + Py/EIA cells, which was dependent on a high tyrosine phosphatase activity, as shown by orthovanadate blockade. An ERK1/2 tyrosine phosphatase was likely involved. The high tyrosine phosphatase activity was instrumental to the complete suppression of senescence, detected by β-galactosidase activity, because tyrosine phosphatase blockade induced senescence in EIA + raf but not in EIA + Py cells. High tyrosine phosphatase activity and evasion from senescence were confirmed in an anaplastic thyroid cancer cell line. Therefore, besides EIA, EIA + raf cells suppress senescence through a new mechanism, namely, phosphatase-mediated P-ERK1/2 inhibition, but, paradoxically, retain the oncogenic effects of the Raf-ERK pathway. We propose that the survival effect of Raf is not a function of absolute P-ERK1/2 levels at a given time but is rather dynamically dependent on greater variations after an apoptotic stimulus.

Extracellular signal-regulated protein kinases 1 and 2 activation by addictive drugs: a signal toward pathological adaptation.

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Pascoli, Vincent; Cahill, Emma; Bellivier, Frank; Caboche, Jocelyne; Vanhoutte, Peter

2014-12-15

Addiction is a chronic and relapsing psychiatric disorder that is thought to occur in vulnerable individuals. Synaptic plasticity evoked by drugs of abuse in the so-called neuronal circuits of reward has been proposed to underlie behavioral adaptations that characterize addiction. By increasing dopamine in the striatum, addictive drugs alter the balance of dopamine and glutamate signals converging onto striatal medium-sized spiny neurons (MSNs) and activate intracellular events involved in long-term behavioral alterations. Our laboratory contributed to the identification of salient molecular changes induced by administration of addictive drugs to rodents. We pioneered the observation that a common feature of addictive drugs is to activate, by a double tyrosine/threonine phosphorylation, the extracellular signal-regulated kinases 1 and 2 (ERK1/2) in the striatum, which control a plethora of substrates, some of them being critically involved in cocaine-mediated molecular and behavioral adaptations. Herein, we review how the interplay between dopamine and glutamate signaling controls cocaine-induced ERK1/2 activation in MSNs. We emphasize the key role of N-methyl-D-aspartate receptor potentiation by D1 receptor to trigger ERK1/2 activation and its subsequent nuclear translocation where it modulates both epigenetic and genetic processes engaged by cocaine. We discuss how cocaine-induced long-term synaptic and structural plasticity of MSNs, as well as behavioral adaptations, are influenced by ERK1/2-controlled targets. We conclude that a better knowledge of molecular mechanisms underlying ERK1/2 activation by drugs of abuse and/or its role in long-term neuronal plasticity in the striatum may provide a new route for therapeutic treatment in addiction. Copyright © 2014 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Simvastatin attenuates acrolein-induced mucin production in rats: involvement of the Ras/extracellular signal-regulated kinase pathway.

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Chen, Ya-Juan; Chen, Peng; Wang, Hai-Xia; Wang, Tao; Chen, Lei; Wang, Xun; Sun, Bei-Bei; Liu, Dai-Shun; Xu, Dan; An, Jing; Wen, Fu-Qiang

2010-06-01

Airway mucus overproduction is a cardinal feature of airway inflammatory diseases, such as chronic obstructive pulmonary disease and cystic fibrosis. Since the small G-protein Ras is known to modulate cellular functions in the lung, we sought to investigate whether the Ras inhibitor simvastatin could attenuate acrolein-induced mucin production in rat airways. Rats were exposed to acrolein for 12 days, after first being pretreated intragastrically for 24 h with either simvastatin alone or simvastatin in combination with mevalonate, which prevents the isoprenylation needed for Ras activation. Lung tissue was analyzed for extracellular signal-regulated kinase (ERK) activity, goblet cell metaplasia and mucin production. To analyze the effect of simvastatin on mucin production in more detail, acrolein-exposed human airway epithelial NCI-H292 cells were pretreated with simvastatin alone or together with mevalonate. Culture medium was collected to detect mucin secretion, and cell lysates were examined for Ras-GTPase activity and epidermal growth factor receptor (EGFR)/ERK phosphorylation. In vivo, simvastatin treatment dose-dependently suppressed acrolein-induced goblet cell hyperplasia and metaplasia in bronchial epithelium and inhibited ERK phosphorylation in rat lung homogenates. Moreover, simvastatin inhibited Muc5AC mucin synthesis at both the mRNA and protein levels in the lung. In vitro, simvastatin pretreatment attenuated the acrolein-induced significant increase in MUC5AC mucin expression, Ras-GTPase activity and EGFR/ERK phosphorylation. These inhibitory effects of simvastatin were neutralized by mevalonate administration both in vitro and in vivo. Our results suggest that simvastatin may attenuate acrolein-induced mucin protein synthesis in the airway and airway inflammation, possibly by blocking ERK activation mediated by Ras protein isoprenylation. Thus, the evidence from the experiment suggests that human trials are warranted to determine the potential

Heparan sulfate proteoglycans mediate interstitial flow mechanotransduction regulating MMP-13 expression and cell motility via FAK-ERK in 3D collagen.

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Zhong-Dong Shi

2011-01-01

Full Text Available Interstitial flow directly affects cells that reside in tissues and regulates tissue physiology and pathology by modulating important cellular processes including proliferation, differentiation, and migration. However, the structures that cells utilize to sense interstitial flow in a 3-dimensional (3D environment have not yet been elucidated. Previously, we have shown that interstitial flow upregulates matrix metalloproteinase (MMP expression in rat vascular smooth muscle cells (SMCs and fibroblasts/myofibroblasts via activation of an ERK1/2-c-Jun pathway, which in turn promotes cell migration in collagen. Herein, we focused on uncovering the flow-induced mechanotransduction mechanism in 3D.Cleavage of rat vascular SMC surface glycocalyx heparan sulfate (HS chains from proteoglycan (PG core proteins by heparinase or disruption of HS biosynthesis by silencing N-deacetylase/N-sulfotransferase 1 (NDST1 suppressed interstitial flow-induced ERK1/2 activation, interstitial collagenase (MMP-13 expression, and SMC motility in 3D collagen. Inhibition or knockdown of focal adhesion kinase (FAK also attenuated or blocked flow-induced ERK1/2 activation, MMP-13 expression, and cell motility. Interstitial flow induced FAK phosphorylation at Tyr925, and this activation was blocked when heparan sulfate proteoglycans (HSPGs were disrupted. These data suggest that HSPGs mediate interstitial flow-induced mechanotransduction through FAK-ERK. In addition, we show that integrins are crucial for mechanotransduction through HSPGs as they mediate cell spreading and maintain cytoskeletal rigidity.We propose a conceptual mechanotransduction model wherein cell surface glycocalyx HSPGs, in the presence of integrin-mediated cell-matrix adhesions and cytoskeleton organization, sense interstitial flow and activate the FAK-ERK signaling axis, leading to upregulation of MMP expression and cell motility in 3D. This is the first study to describe a flow-induced mechanotransduction

The nitric oxide-sensitive p21Ras-ERK pathway mediates S-nitrosoglutathione-induced apoptosis

International Nuclear Information System (INIS)

Tsujita, Maristela; Batista, Wagner L.; Ogata, Fernando T.; Stern, Arnold; Monteiro, Hugo P.; Arai, Roberto J.

2008-01-01

p21Ras protein plays a critical role in cellular signaling that induces either cell cycle progression or apoptosis. Nitric oxide (NO) has been consistently reported to activate p21Ras through the redox sensitive cysteine residue (118). In this study, we demonstrated that the p21Ras-ERK pathway regulates THP-1 monocyte/macrophage apoptosis induced by S-nitrosoglutathione (SNOG). This was apparent from studies in THP-1 cells expressing NO-insensitive p21Ras (p21Ras C118S ) where the pro-apoptotic action of SNOG was almost abrogated. Three major MAP kinase pathways (ERK, JNK, and p38) that are downstream to p21Ras were investigated. It was observed that only the activation of ERK1/2 MAP kinases by SNOG in THP-1 cells was attributable to p21Ras. The inhibition of the ERK pathway by PD98059 markedly attenuated apoptosis in SNOG-treated THP-1 cells, but had a marginal effect on SNOG-treated THP-1 cells expressing NO-insensitive p21Ras. The inhibition of the JNK and p38 pathways by selective inhibitors had no marked effects on the percentage of apoptosis. The induction of p21Waf1 expression by SNOG was observed in THP-1 cells harboring mutant and wild-type p21Ras, however in cells expressing mutant Ras, the expression of p21Waf1 was significantly attenuated. The treatment of THP-1 cells expressing wild-type p21Ras with PD98059 resulted in significant attenuation of p21Waf1 expression. These results indicate that the redox sensitive p21Ras-ERK pathway plays a critical role in sensing and delivering the pro-apoptotic signaling mediated by SNOG

Fucoxanthin prevents H2O2-induced neuronal apoptosis via concurrently activating the PI3-K/Akt cascade and inhibiting the ERK pathway.

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Yu, Jie; Lin, Jia-Jia; Yu, Rui; He, Shan; Wang, Qin-Wen; Cui, Wei; Zhang, Jin-Rong

2017-01-01

Background : As a natural carotenoid abundant in chloroplasts of edible brown algae, fucoxanthin possesses various health benefits, including anti-oxidative activity in particular. Objective : In the present study, we studied whether fucoxanthin protected against hydrogen peroxide (H 2 O 2 )-induced neuronal apoptosis. Design : The neuroprotective effects of fucoxanthin on H 2 O 2 -induced toxicity were studied in both SH-SY5Y cells and primary cerebellar granule neurons. Results : Fucoxanthin significantly protected against H 2 O 2 -induced neuronal apoptosis and intracellular reactive oxygen species. H 2 O 2 treatment led to the reduced activity of phosphoinositide 3-kinase (PI3-K)/Akt cascade and the increased activity of extracellular signal-regulated kinase (ERK) pathway in SH-SY5Y cells. Moreover, fucoxanthin significantly restored the altered activities of PI3-K/Akt and ERK pathways induced by H 2 O 2 . Both specific inhibitors of glycogen synthase kinase 3β (GSK3β) and mitogen-activated protein kinase kinase (MEK) significantly protected against H 2 O 2 -induced neuronal death. Furthermore, the neuroprotective effects of fucoxanthin against H 2 O 2 -induced neuronal death were abolished by specific PI3-K inhibitors. Conclusions : Our data strongly revealed that fucoxanthin protected against H 2 O 2 -induced neurotoxicity via concurrently activating the PI3-K/Akt cascade and inhibiting the ERK pathway, providing support for the use of fucoxanthin to treat neurodegenerative disorders induced by oxidative stress.

Plasmalogens rescue neuronal cell death through an activation of AKT and ERK survival signaling.

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Md Shamim Hossain

Full Text Available Neuronal cells are susceptible to many stresses, which will cause the apoptosis and neurodegenerative diseases. The precise molecular mechanism behind the neuronal protection against these apoptotic stimuli is necessary for drug discovery. In the present study, we have found that plasmalogens (Pls, which are glycerophospholipids containing vinyl ether linkage at sn-1 position, can protect the neuronal cell death upon serum deprivation. Interestingly, caspse-9, but not caspase-8 and caspase-12, was cleaved upon the serum starvation in Neuro-2A cells. Pls treatments effectively reduced the activation of caspase-9. Furthermore, cellular signaling experiments showed that Pls enhanced phosphorylation of the phosphoinositide 3-kinase (PI3K-dependent serine/threonine-specific protein kinase AKT and extracellular-signal-regulated kinases ERK1/2. PI3K/AKT inhibitor LY294002 and MAPK/ERK kinase (MEK inhibitor U0126 treatments study clearly indicated that Pls-mediated cell survival was dependent on the activation of these kinases. In addition, Pls also inhibited primary mouse hippocampal neuronal cell death induced by nutrient deprivation, which was associated with the inhibition of caspase-9 and caspase-3 cleavages. It was reported that Pls content decreased in the brain of the Alzheimer's patients, which indicated that the reduction of Pls content could endanger neurons. The present findings, taken together, suggest that Pls have an anti-apoptotic action in the brain. Further studies on precise mechanisms of Pls-mediated protection against cell death may lead us to establish a novel therapeutic approach to cure neurodegenerative disorders.

On the nanotoxicity of PAMAM dendrimers: Superfect® stimulates the EGFR-ERK1/2 signal transduction pathway via an oxidative stress-dependent mechanism in HEK 293 cells.

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Akhtar, Saghir; Chandrasekhar, Bindu; Attur, Sreeja; Yousif, Mariam H M; Benter, Ibrahim F

2013-05-01

Polyamidoamine (PAMAM) dendrimers are cationic branch-like macromolecules that may serve as drug delivery systems for gene-based therapies such as RNA interference. For their safe use in the clinic, they should ideally only enhance drug delivery to target tissues and exhibit no adverse effects. However, little is known about their toxicological profiles in terms of their interactions with cellular signal transduction pathways such as the epidermal growth factor receptor (EGFR). The EGFR is an important signaling cascade that regulates cell growth, differentiation, migration, survival and apoptosis. Here, we investigated the impact of naked, unmodified Superfect (SF), a commercially available generation 6 PAMAM dendrimer, on the epidermal growth factor receptor (EGFR) tyrosine kinase-extracellular-regulated kinase 1/2 (ERK1/2) signaling pathway in human embryonic kidney (HEK 293) cells. At concentrations routinely used for transfection, SF exhibited time and dose-dependent stimulation of EGFR and ERK1/2 phosphorylation whereas AG1478, a selective EGFR tyrosine kinase antagonist, inhibited EGFR-ERK1/2 signaling. SF-induced phosphorylation of EGFR for 1h was partly reversible upon removal of the dendrimer and examination of cells 24 later. Co-treatment of SF with epidermal growth factor (EGF) ligand resulted in greater EGFR stimulation than either agent alone implying that the stimulatory effects of SF and the ligand are synergistic. Dendrimer-induced stimulation of EGFR-ERK1/2 signaling could be attenuated by the antioxidants apocynin, catalase and tempol implying that an oxidative stress dependent mechanism was involved. These results show for the first time that PAMAM dendrimers, aside from their ability to improve drug delivery, can modulate the important EGFR-ERK1/2 cellular signal transduction pathway - a novel finding that may have a bearing on their safe application as drug delivery systems. Copyright © 2013 Elsevier B.V. All rights reserved.

Icaritin induces MC3T3-E1 subclone14 cell differentiation through estrogen receptor-mediated ERK1/2 and p38 signaling activation.

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Wu, Zhidi; Ou, Ling; Wang, Chaopeng; Yang, Li; Wang, Panpan; Liu, Hengrui; Xiong, Yingquan; Sun, Kehuan; Zhang, Ronghua; Zhu, Xiaofeng

2017-10-01

Icaritin (ICT), a hydrolytic product of icariin from the genus Epimedium, has many indicated pharmacological and biological activities. Several studies have shown that ICT has potential osteoprotective effects, including stimulation of osteoblast differentiation and inhibition of osteoclast differentiation. However, the molecular mechanism for this anabolic action of ICT remains largely unknown. Here, we found that ICT could enhance MC3T3-E1 subclone 14 preosteoblastic cell differentiation associated with increased mRNA levels and protein expression of the differentiation markers alkaline phosphatase (ALP), type 1 collagen (COL1), osteocalcin (OC), osteoponin (OPN) and runt-related transcription factor 2 (RUNX2), and improved mineralization, confirmed by bone nodule formation and collagen synthesis. To characterize the underlying mechanisms, we examined the effect of ICT on estrogen receptor (ER) and mitogen-activated protein kinase (MAPK) signaling. ICT treatment induced p38 kinase and extracellular signal-regulated kinase 1/2 (ERK1/2) activation, but it demonstrated at the same time point no effect on activation of c-Jun N-terminal kinase (JNK). ER antagonist ICI182780, p38 antagonist SB203580 and ERK1/2 antagonist PD98059 markedly inhibited the ICT-induced the mRNA expression of ALP, COL1, OC and OPN. ICI182780 attenuated the ICT-induced phosphorylation of p38 and ERK1/2. These observations indicate a potential mechanism of osteogenic effects of ICT involving the ERK1/2 and p38 pathway activation through the ER. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Sodium Ferulate Prevents Daunorubicin - Induced Apoptosis in H9c2 Cells via Inhibition of the ERKs Pathway

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Zhi-Juan Wu

2015-07-01

Full Text Available Background: Daunorubicin (DNR-induced cardiotoxicity, which is closely associated with cardiomyocyte apoptosis, limits the drug's clinical application. The activation of the extracellular regulated protein kinases (ERKs pathway is responsible for the pro-apoptosis effect of DNR Sodium ferulate (SF has recently been found to attenuate both DNR-induced cardiotoxicity and mitochondrial apoptosis in juvenile rats. Nonetheless, the precise mechanism underlying SF-induced cardio-protection remains unclear. Methods: The DNR-injured H9c2 cell model was prepared by incubating the cells in 1 µM DNR for 24 h. Amounts of 15.6, 31.3 or 62.5 µM SF were simultaneously added to the cells. The effect of SF on the cytotoxic and apoptotic parameters of the cells was studied by monitoring apoptosis regulation via the ERKs pathway. Results: SF attenuated DNR-induced cell death (particularly apoptotic death, cTnI and β-tubulin degradation, and cellular morphological changes. SF reduced mitochondrial membrane potential depolarization, cytochrome c leakage, and caspase-9 and caspase-3 activation. SF also decreased ERK1/2, phospho-ERK1/2, p53 and Bax expression and increased Bcl-2 expression. These effects were similar to the results observed when using the pharmacological ERKs phosphorylation inhibitor, AZD6244. Conclusion: We determined that SF protects H9c2 cells from DNR-induced apoptosis through a mechanism that involves the interruption of the ERKs signaling pathway.

Phospholipase D1 mediates AMP-activated protein kinase signaling for glucose uptake.

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Jong Hyun Kim

2010-03-01

Full Text Available Glucose homeostasis is maintained by a balance between hepatic glucose production and peripheral glucose utilization. In skeletal muscle cells, glucose utilization is primarily regulated by glucose uptake. Deprivation of cellular energy induces the activation of regulatory proteins and thus glucose uptake. AMP-activated protein kinase (AMPK is known to play a significant role in the regulation of energy balances. However, the mechanisms related to the AMPK-mediated control of glucose uptake have yet to be elucidated.Here, we found that AMPK-induced phospholipase D1 (PLD1 activation is required for (14C-glucose uptake in muscle cells under glucose deprivation conditions. PLD1 activity rather than PLD2 activity is significantly enhanced by glucose deprivation. AMPK-wild type (WT stimulates PLD activity, while AMPK-dominant negative (DN inhibits it. AMPK regulates PLD1 activity through phosphorylation of the Ser-505 and this phosphorylation is increased by the presence of AMP. Furthermore, PLD1-S505Q, a phosphorylation-deficient mutant, shows no changes in activity in response to glucose deprivation and does not show a significant increase in (14C-glucose uptake when compared to PLD1-WT. Taken together, these results suggest that phosphorylation of PLD1 is important for the regulation of (14C-glucose uptake. In addition, extracellular signal-regulated kinase (ERK is stimulated by AMPK-induced PLD1 activation through the formation of phosphatidic acid (PA, which is a product of PLD. An ERK pharmacological inhibitor, PD98059, and the PLD inhibitor, 1-BtOH, both attenuate (14C-glucose uptake in muscle cells. Finally, the extracellular stresses caused by glucose deprivation or aminoimidazole carboxamide ribonucleotide (AICAR; AMPK activator regulate (14C-glucose uptake and cell surface glucose transport (GLUT 4 through ERK stimulation by AMPK-mediated PLD1 activation.These results suggest that AMPK-mediated PLD1 activation is required for (14C

Exposure to a specific time-varying electromagnetic field inhibits cell proliferation via cAMP and ERK signaling in cancer cells.

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Buckner, Carly A; Buckner, Alison L; Koren, Stan A; Persinger, Michael A; Lafrenie, Robert M

2018-04-01

Exposure to specific electromagnetic field (EMF) patterns can affect a variety of biological systems. We have shown that exposure to Thomas-EMF, a low-intensity, frequency-modulated (25-6 Hz) EMF pattern, inhibited growth and altered cell signaling in malignant cells. Exposure to Thomas-EMF for 1 h/day inhibited the growth of malignant cells including B16-BL6 mouse melanoma cells, MDA-MB-231, MDA-MB-468, BT-20, and MCF-7 human breast cancer and HeLa cervical cancer cells but did not affect non-malignant cells. The Thomas-EMF-dependent changes in cell proliferation were mediated by adenosine 3',5'-cyclic monophosphate (cAMP) and extracellular-signal-regulated kinase (ERK) signaling pathways. Exposure of malignant cells to Thomas-EMF transiently changed the level of cellular cAMP and promoted ERK phosphorylation. Pharmacologic inhibitors (SQ22536) and activators (forskolin) of cAMP production both blocked the ability of Thomas-EMF to inhibit cell proliferation, and an inhibitor of the MAP kinase pathway (PD98059) was able to partially block Thomas-EMF-dependent inhibition of cell proliferation. Genetic modulation of protein kinase A (PKA) in B16-BL6 cells also altered the effect of Thomas-EMF on cell proliferation. Cells transfected with the constitutively active form of PKA (PKA-CA), which interfered with ERK phosphorylation, also interfered with the Thomas-EMF effect on cell proliferation. The non-malignant cells did not show any EMF-dependent changes in cAMP levels, ERK phosphorylation, or cell growth. These data indicate that exposure to the specific Thomas-EMF pattern can inhibit the growth of malignant cells in a manner dependent on contributions from the cAMP and MAP kinase pathways. Bioelectromagnetics. 39;217-230, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Sweet Dream Liquid Chinese Medicine Ameliorates Learning and Memory Deficit in a Rat Model of Paradoxical Sleep Deprivation through the ERK/CREB Signaling Pathway.

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Su, Xinyun; Wang, Chunhua; Wang, Xiuhua; Han, Fang; Lv, Changjun; Zhang, Xiuli

2016-05-01

Sweet dream oral liquid (SDOL), a traditional Chinese herbal compound contains 17 traditional Chinese medicines. It has various pharmacological effects, such as improving brain dysfunction and increasing sleeping quality. This study investigated the neuroprotective effect and the underlying mechanisms of SDOL-impaired hippocampus learning and memory-induced paradoxical sleep deprivation (PSD) in rats. Sixty Male Wistar rats were randomly divided into six groups. Before PSD, SDOL treatment group rats were intragastrically administered SDOL for 25 days at dose of 2.1, 4.2, and 8.4 mL/kg body weight per day. Normal control group, large platform control group, and PSD groups were treated with normal saline instead of SDOL. After 25 days treatment, PSD and SDOL groups were deprived of paradoxical sleep for 72 h. Then two behavioral studies were conducted to test the spatial learning and memory ability using the open field test and Morris water maze test. Expression of the c-fos, c-jun, cyclic AMP response element binding protein (CREB), extracellular signal-regulated protein kinase (ERK), mitogen-activated protein kinases (MAPK)/ERK kinase (MEK), and p-CREB, p-ERK, and p-MEK in the hippocampus were also assayed by western blot. In this study, PSD decreased the levels of p-CREB, p-ERK, p-MEK, c-fos, and c-jun. However, SDOL treatment increased expressions of these proteins. Our results showed that SDOL improved 72-h PSD-induced cognitive impairment. These affects may be mediated by increasing the contents of c-fos, c-jun, and p-CREB/ERK signaling.

Dihydrotestosterone Potentiates EGF-Induced ERK Activation by Inducing SRC in Fetal Lung Fibroblasts

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Smith, Susan M.; Murray, Sandy; Pham, Lucia D.; Minoo, Parviz; Nielsen, Heber C.

2014-01-01

Lung maturation is regulated by interactions between mesenchymal and epithelial cells, and is delayed by androgens. Fibroblast–Type II cell communications are dependent on extracellular signal-regulated kinases (ERK) 1/2 activation by the ErbB receptor ligands epidermal growth factor (EGF), transforming growth factor (TGF)-α, and neuregulin (Nrg). In other tissues, dihydrotestosterone (DHT) has been shown to activate SRC by a novel nontranscriptional mechanism, which phosphorylates EGF receptors to potentiate EGF-induced ERK1/2 activation. This study sought to determine if DHT potentiates EGFR signaling by a nontranscriptional mechanism. Embryonic day (E)17 fetal lung cells were isolated from dams treated with or without DHT since E12. Cells were exposed to 30 ng/ml DHT for periods of 30 minutes to 3 days before being stimulated with 100 ng/ml EGF, TGF-α, or Nrg for up to 30 minutes. Lysates were immunoblotted for ErbB and SRC pathway signaling intermediates. DHT increased ERK1/2 activation by EGF, TGF-α, and Nrg in fibroblasts and Type II cells. Characterization in fibroblasts showed that potentiation of the EGF pathway was significant after 60 minutes of DHT exposure and persisted in the presence of the translational inhibitor cycloheximide. SRC and EGF receptor phosphorylation was increased by DHT, as was EGF-induced SHC1 phosphorylation and subsequent association with GRB2. Finally, SRC silencing, SRC inhibition with PP2, and overexpression of a dominant-negative SRC each prevented DHT from increasing EGF-induced ERK1/2 phosphorylation. These results suggest that DHT activates SRC to potentiate the signaling pathway leading from the EGF receptor to ERK activation in primary fetal lung fibroblasts. PMID:24484548

Outer Membrane Protein 25 of Brucella Activates Mitogen-Activated Protein Kinase Signal Pathway in Human Trophoblast Cells

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Jing Zhang

2017-12-01

Full Text Available Outer membrane protein 25 (OMP25, a virulence factor from Brucella, plays an important role in maintaining the structural stability of Brucella. Mitogen-activated protein kinase (MAPK signal pathway widely exists in eukaryotic cells. In this study, human trophoblast cell line HPT-8 and BALB/c mice were infected with Brucella abortus 2308 strain (S2308 and 2308ΔOmp25 mutant strain. The expression of cytokines and activation of MAPK signal pathway were detected. We found that the expressions of tumor necrosis factor-α, interleukin-1, and interleukin-10 (IL-10 were increased in HPT-8 cells infected with S2308 and 2308ΔOmp25 mutant. S2308 also activated p38 phosphorylation protein, extracellular-regulated protein kinases (ERK, and Jun-N-terminal kinase (JNK from MAPK signal pathway. 2308ΔOmp25 could not activate p38, ERK, and JNK branches. Immunohistochemistry experiments showed that S2308 was able to activate phosphorylation of p38 and ERK in BABL/c mice. However, 2308ΔOmp25 could weakly activate phosphorylation of p38 and ERK. These results suggest that Omp25 played an important role in the process of Brucella activation of the MAPK signal pathway.

Protein kinase A-mediated cell proliferation in brown preadipocytes is independent of Erk1/2, PI3K and mTOR

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Wang, Yanling; Sato, Masaaki; Guo, Yuan; Bengtsson, Tore; Nedergaard, Jan

2014-01-01

The physiological agonist norepinephrine promotes cell proliferation of brown preadipocytes during the process of tissue recruitment. In a primary culture system, cAMP mediates these adrenergic effects. In the present study, we demonstrated that, in contrast to other systems where the mitogenic effect of cAMP requires the synergistic action of (serum) growth factors, especially insulin/IGF, the cAMP effect in brown preadipocytes was independent of serum and insulin. Protein kinase A, rather than Epac, mediated the cAMP mitogenic effect. The Erk 1/2 family of MAPK, the PI 3 K system and the mTOR complexes were all activated by cAMP, but these activations were not necessary for cAMP-induced cell proliferation; a protein kinase C isoform may be involved in mediating cAMP-activated cell proliferation. We conclude that the generally acknowledged cellular mediators for induction of cell proliferation are not involved in this process in the brown preadipocyte system; this conclusion may be of relevance both for examination of mechanisms for induction of brown adipose tissue recruitment but also for understanding the mechanism behind e.g. certain endocrine neoplasias. - Highlights: • cAMP can mimick norepinephrine-induced proliferation of brown preadipocytes. • The cAMP-induced proliferation can occur in the absence of serum, of any other growth factors, and of insulin. • Erk1/2, PI 3 K and mTOR are cAMP activated but not involved in induction of proliferation. • A Protein Kinase C member may be in the signalling cascade. • This pathway analysis may also be of importance for certain endocrine hyper- and neoplasias

Effects of L-cysteine on reinstatement of ethanol-seeking behavior and on reinstatement-elicited extracellular signal-regulated kinase phosphorylation in the rat nucleus accumbens shell.

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Peana, Alessandra T; Giugliano, Valentina; Rosas, Michela; Sabariego, Marta; Acquas, Elio

2013-01-01

Alcoholism is a neuroadaptive disorder, and the understanding of the mechanisms of the high rates of relapse, which characterize it, represents one of the most demanding challenges in alcoholism and addiction research. The extracellular signal-regulated kinase (ERK) is an intracellular kinase, critical for neuroplasticity in the adult brain that is suggested to play a fundamental role in the molecular mechanisms underlying drug addiction and relapse. We previously observed that a nonessential amino acid, L-cysteine, significantly decreases oral ethanol (EtOH) self-administration, reinstatement of EtOH-drinking behavior, and EtOH self-administration break point. Here, we tested whether L-cysteine can affect the ability of EtOH priming to induce reinstatement of EtOH-seeking behavior. In addition, we determined the ability of EtOH priming to induce ERK phosphorylation as well as the ability of L-cysteine to affect reinstatement-elicited ERK activation. To these purposes, Wistar rats were trained to nose-poke for a 10% v/v EtOH solution. After stable drug-taking behavior was obtained, nose-poking for EtOH was extinguished, and reinstatement of drug seeking, as well as reinstatement-elicited pERK, was determined after an oral, noncontingent, priming of EtOH (0.08 g/kg). Rats were pretreated with either saline or L-cysteine (80 to 120 mg/kg) 30 minutes before testing for reinstatement. The findings of this study confirm that the noncontingent delivery of a nonpharmacologically active dose of EtOH to rats, whose previous self-administration behavior had been extinguished, results in significant reinstatement into EtOH-seeking behavior. In addition, the results indicate that reinstatement selectively activates ERK phosphorylation in the shell of the nucleus accumbens (Acb) and that pretreatment with L-cysteine reduces either reinstatement of EtOH seeking and reinstatement-elicited pERK in the AcbSh. Altogether, these results indicate that L-cysteine could be an effective

Po2 cycling protects diaphragm function during reoxygenation via ROS, Akt, ERK, and mitochondrial channels.

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Zuo, Li; Pannell, Benjamin K; Re, Anthony T; Best, Thomas M; Wagner, Peter D

2015-12-01

Po2 cycling, often referred to as intermittent hypoxia, involves exposing tissues to brief cycles of low oxygen environments immediately followed by hyperoxic conditions. After experiencing long-term hypoxia, muscle can be damaged during the subsequent reintroduction of oxygen, which leads to muscle dysfunction via reperfusion injury. The protective effect and mechanism behind Po2 cycling in skeletal muscle during reoxygenation have yet to be fully elucidated. We hypothesize that Po2 cycling effectively increases muscle fatigue resistance through reactive oxygen species (ROS), protein kinase B (Akt), extracellular signal-regulated kinase (ERK), and certain mitochondrial channels during reoxygenation. Using a dihydrofluorescein fluorescent probe, we detected the production of ROS in mouse diaphragmatic skeletal muscle in real time under confocal microscopy. Muscles treated with Po2 cycling displayed significantly attenuated ROS levels (n = 5; P ROS, Akt, ERK, as well as chemical stimulators to close mitochondrial ATP-sensitive potassium channel (KATP) or open mitochondrial permeability transition pore (mPTP). All these blockers or stimulators abolished improved muscle function with Po2 cycling treatment. This current investigation has discovered a correlation between KATP and mPTP and the Po2 cycling pathway in diaphragmatic skeletal muscle. Thus we have identified a unique signaling pathway that may involve ROS, Akt, ERK, and mitochondrial channels responsible for Po2 cycling protection during reoxygenation conditions in the diaphragm. Copyright © 2015 the American Physiological Society.

The progesterone-induced enhancement of object recognition memory consolidation involves activation of the extracellular signal-regulated kinase (ERK) and mammalian target of rapamycin (mTOR) pathways in the dorsal hippocampus

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Orr, Patrick T.; Rubin, Amanda J.; Fan, Lu; Kent, Brianne A.; Frick, Karyn M.

2012-01-01

Although much recent work has elucidated the biochemical mechanisms underlying the modulation of memory by 17β-estradiol, little is known about the signaling events through which progesterone (P) regulates memory. We recently demonstrated that immediate post-training infusion of P into the dorsal hippocampus enhances object recognition memory consolidation in young ovariectomized female mice (Orr et al., 2009). The goal of the present study was to identify the biochemical alterations that might underlie this mnemonic enhancement. We hypothesized that the P-induced enhancement of object recognition would be dependent on activation of the ERK and mTOR pathways. In young ovariectomized mice, we found that bilateral dorsal hippocampal infusion of P significantly increased levels of phospho-p42 ERK and the mTOR substrate S6K in the dorsal hippocampus 5 minutes after infusion. Phospho-p42 ERK levels were downregulated 15 minutes after infusion and returned to baseline 30 minutes after infusion, suggesting a biphasic effect of P on ERK activation. Dorsal hippocampal ERK and mTOR activation were necessary for P to facilitate memory consolidation, as suggested by the fact that inhibitors of both pathways infused into the dorsal hippocampus immediately after training blocked the P-induced enhancement of object recognition. Collectively, these data provide the first demonstration that the ability of P to enhance memory consolidation depends on the rapid activation of cell signaling and protein synthesis pathways in the dorsal hippocampus. PMID:22265866

Triiodothyronine promotes the proliferation of epicardial progenitor cells through the MAPK/ERK pathway

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Deng, Song-Bai; Jing, Xiao-Dong; Wei, Xiao-ming; Du, Jian-Lin; Liu, Ya-Jie; Qin, Qin; She, Qiang

2017-01-01

Thyroid hormone has important functions in the development and physiological function of the heart. The aim of this study was to determine whether 3,5,3′-Triiodothyronine (T3) can promote the proliferation of epicardial progenitor cells (EPCs) and to investigate the potential underlying mechanism. Our results showed that T3 significantly promoted the proliferation of EPCs in a concentration- and time-dependent manner. The thyroid hormone nuclear receptor inhibitor bisphenol A (100 μmol/L) did not affect T3's ability to induce proliferation. Further studies showed that the mRNA expression levels of mitogen-activated protein kinase 1 (MAPK1), MAPK3, and Ki67 in EPCs in the T3 group (10 nmol/L) increased 2.9-, 3-, and 4.1-fold, respectively, compared with those in the control group (P < 0.05). In addition, the mRNA expression of the cell cycle protein cyclin D1 in the T3 group increased approximately 2-fold compared with the control group (P < 0.05), and there were more EPCs in the S phase of the cell cycle (20.6% vs. 12.0%, P < 0.05). The mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling pathway inhibitor U0126 (10 μmol/L) significantly inhibited the ability of T3 to promote the proliferation of EPCs and to alter cell cycle progression. This study suggested that T3 significantly promotes the proliferation of EPCs, and this effect may be achieved through activation of the MAPK/ERK signaling pathway. - Highlights: • Epicardial progenitor cells were successfully cultured from E12.5 mice. • Thyroid hormone T3 significantly promoted the proliferation of EPCs. • This biological effect may be mediated via activation of the MAPK/ERK pathway.

Mechano-growth factor induces migration of rat mesenchymal stem cells by altering its mechanical properties and activating ERK pathway

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Wu, Jiamin; Wu, Kewen; Lin, Feng; Luo, Qing; Yang, Li; Shi, Yisong [Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044 (China); Song, Guanbin, E-mail: song@cqu.edu.cn [Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044 (China); Sung, Kuo-Li Paul [Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044 (China); Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093-0412 (United States)

2013-11-08

Highlights: •MGF induced the migration of rat MSC in a concentration-dependent manner. •MGF enhanced the mechanical properties of rMSC in inducing its migration. •MGF activated the ERK 1/2 signaling pathway of rMSC in inducing its migration. •rMSC mechanics may synergy with ERK 1/2 pathway in MGF-induced rMSC migration. -- Abstract: Mechano-growth factor (MGF) generated by cells in response to mechanical stimulation has been identified as a mechano effector molecule, playing a key role in regulating mesenchymal stem cell (MSC) function, including proliferation and migration. However, the mechanism(s) underlying how MGF-induced MSC migration occurs is still unclear. In the present study, MGF motivated migration of rat MSCs (rMSCs) in a concentration-dependent manner and optimal concentration of MGF at 50 ng/mL (defined as MGF treatment in this paper) was demonstrated. Notably, enhancement of mechanical properties that is pertinent to cell migration, such as cell traction force and cell stiffness were found to respond to MGF treatment. Furthermore, MGF increased phosphorylation of extracellular signal-regulated kinase (ERK), ERK inhibitor (i.e., PD98059) suppressed ERK phosphorylation, and abolished MGF-induced rMSC migration were found, demonstrating that ERK is involved molecule for MGF-induced rMSC migration. These in vitro evidences of MGF-induced rMSC migration and its direct link to altering rMSC mechanics and activating the ERK pathway, uncover the underlying biomechanical and biological mechanisms of MGF-induced rMSC migration, which may help find MGF-based application of MSC in clinical therapeutics.

ERK/CANP rapid signaling mediates 17β-estradiol-induced proliferation of human breast cancer cell line MCF-7 cells.

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Wang, Guo-Sheng; Huang, Yan-Gang; Li, Huan; Bi, Shi-Jie; Zhao, Jin-Long

2014-01-01

17β-estradiol (E2) exerts its functions through both genomic and non-genomic signaling pathways. Because E2 is important in breast cancer development, we investigated whether its actions in promoting breast cancer cell proliferation occur through the non-genomic signaling pathway via extracellular signal-regulated kinase 1/2 (ERK1/2)/calcium-activated neutral protease (CANP). MCF-7 breast cancer cells were treated with ERKl/2 inhibitor (PD98059) or CANP inhibitor (calpeptin) before exposure to 1×10(-8) M E2. MTT colorimetry and flow cytometry were used to analyze effects on cell proliferation and cell cycle progression, respectively. Expression of phosphorylated-ERK (p-ERK), total ERK, and Capn4 proteins were assessed by Western blotting. Cell proliferation increased in cells treated with E2 for 24 h (P<0.05), and the proportion of cells in G0/G1 was decreased, accompanied by accelerated G1/S. Calpeptin pre-treatment significantly inhibited the E2-induced proliferation of MCF-7 cells (P<0.05), while also ameliorating the effects of E2 on cell cycle progression. Further, expression of p-ERK was rapidly up-regulated (after 10 min) by E2 (P<0.05), an effect that persisted 16 h after E2 exposure but which was significantly inhibited by PD98059 (P<0.05). Finally, expression of Capn4 protein was rapidly up-regulated in E2-exposed cells (P<0.05), but this change was significantly inhibited by PD98059 or calpeptin (P<0.05) pre-treatment. Thus, the rapid, non-genomic ERK/CANP signaling pathway mediates E2-induced proliferation of human breast cancer cells.

High glucose enhances cAMP level and extracellular signal-regulated kinase phosphorylation in Chinese hamster ovary cell: Usage of Br-cAMP in foreign protein β-galactosidase expression.

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Lin, Hsiao-Hsien; Lee, Tsung-Yih; Liu, Ting-Wei; Tseng, Ching-Ping

2017-07-01

Glucose is a carbon source for Chinese hamster ovary (CHO) cell growth, while low growth rate is considered to enhance the production of recombinant proteins. The present study reveals that glucose concentrations higher than 1 g/L reduce the growth rate and substantially increase in cAMP (∼300%) at a high glucose concentration (10 g/L). High glucose also enhances the phosphorylation of extracellular signal-regulated kinase (ERK) and p27 kip by Western blot analysis. To determine whether the phosphorylation of ERK is involved in the mechanism, a cyclic-AMP dependent protein kinase A (PKA) inhibitor (H-8) or MEK (MAPKK) inhibitor (PD98059) was added to block ERK phosphorylation. We show that both the high glucose-induced ERK phosphorylation and growth rate return to baseline levels. These results suggest that the cAMP/PKA and MAP signaling pathways are involved in the abovementioned mechanism. Interestingly, the direct addition of 8-bromo-cAMP (Br-cAMP), a membrane-permeable cAMP analog, can mimic the similar effects produced by high glucose. Subsequently Br-cAMP could induce β-galactosidase (β-Gal) recombinant protein expression by 1.6-fold. Furthermore, Br-cAMP can additionally enhance the β-Gal production (from 2.8- to 4.5-fold) when CHO cells were stimulated with glycerol, thymidine, dimethyl sulfoxide, pentanoic acid, or sodium butyrate. Thus, Br-cAMP may be used as an alternative agent in promoting foreign protein expression for CHO cells. Copyright © 2017. Published by Elsevier B.V.

DupA: a key regulator of the amoebal MAP kinase response to Legionella pneumophila

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Li, Zhiru; Dugan, Aisling S.; Bloomfield, Gareth; Skelton, Jason; Ivens, Alasdair; Losick, Vicki; Isberg, Ralph R.

2009-01-01

SUMMARY The dupA gene, encoding a putative tyrosine kinase/dual specificity phosphatase (Dusp), was identified in a screen for Dictyostelium discoideum mutants altered in supporting Legionella pneumophila intracellular replication. The absence of dupA resulted in hyperphosphorylation of ERK1, consistent with the loss of a phosphatase activity, as well as degradation of ERK2. ERK1 hyperphosphorylation mimicked the response of this protein after bacterial challenge of wild type amoebae. Similar to Dusps in higher eukaryotic cells, the amoebal dupA gene was induced after bacterial contact, indicating a response of Dusps that is conserved from amoebae to mammals. A large set of genes was misregulated in the dupA− mutant that largely overlaps with genes responding to L. pneumophila infection. Some of the amoebal genes appear to be involved in a response similar to innate immunity in higher eukaryotes, indicating there was misregulation of a conserved response to bacteria. PMID:19748467

The SH2 domain of Abl kinases regulates kinase autophosphorylation by controlling activation loop accessibility

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Lamontanara, Allan Joaquim; Georgeon, Sandrine; Tria, Giancarlo; Svergun, Dmitri I.; Hantschel, Oliver

2014-11-01

The activity of protein kinases is regulated by multiple molecular mechanisms, and their disruption is a common driver of oncogenesis. A central and almost universal control element of protein kinase activity is the activation loop that utilizes both conformation and phosphorylation status to determine substrate access. In this study, we use recombinant Abl tyrosine kinases and conformation-specific kinase inhibitors to quantitatively analyse structural changes that occur after Abl activation. Allosteric SH2-kinase domain interactions were previously shown to be essential for the leukemogenesis caused by the Bcr-Abl oncoprotein. We find that these allosteric interactions switch the Abl activation loop from a closed to a fully open conformation. This enables the trans-autophosphorylation of the activation loop and requires prior phosphorylation of the SH2-kinase linker. Disruption of the SH2-kinase interaction abolishes activation loop phosphorylation. Our analysis provides a molecular mechanism for the SH2 domain-dependent activation of Abl that may also regulate other tyrosine kinases.

ERK1/2 signaling plays an important role in topoisomerase II poison-induced G2/M checkpoint activation.

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Kolb, Ryan H; Greer, Patrick M; Cao, Phu T; Cowan, Kenneth H; Yan, Ying

2012-01-01

Topo II poisons, which target topoisomerase II (topo II) to generate enzyme mediated DNA damage, have been commonly used for anti-cancer treatment. While clinical evidence demonstrate a capability of topo II poisons in inducing apoptosis in cancer cells, accumulating evidence also show that topo II poison treatment frequently results in cell cycle arrest in cancer cells, which was associated with subsequent resistance to these treatments. Results in this report indicate that treatment of MCF-7 and T47D breast cancer cells with topo II poisons resulted in an increased phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and an subsequent induction of G2/M cell cycle arrest. Furthermore, inhibition of ERK1/2 activation using specific inhibitors markedly attenuated the topo II poison-induced G2/M arrest and diminished the topo II poison-induced activation of ATR and Chk1 kinases. Moreover, decreased expression of ATR by specific shRNA diminished topo II poison-induced G2/M arrest but had no effect on topo II poison-induced ERK1/2 activation. In contrast, inhibition of ERK1/2 signaling had little, if any, effect on topo II poison-induced ATM activation. In addition, ATM inhibition by either incubation of cells with ATM specific inhibitor or transfection of cells with ATM specific siRNA did not block topo II poison-induced G2/M arrest. Ultimately, inhibition of ERK1/2 signaling greatly enhanced topo II poison-induced apoptosis. These results implicate a critical role for ERK1/2 signaling in the activation of G2/M checkpoint response following topo II poison treatment, which protects cells from topo II poison-induced apoptosis.

Thunbergia alata inhibits inflammatory responses through the inactivation of ERK and STAT3 in macrophages.

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Cho, Young-Chang; Kim, Ye Rang; Kim, Ba Reum; Bach, Tran The; Cho, Sayeon

2016-11-01

Thunbergia alata (Acanthaceae) has been used traditionally to treat various inflammatory diseases such as fever, cough and diarrhea in East African countries including Uganda and Kenya. However, systemic studies elucidating the anti-inflammatory effects and precise mechanisms of action of T. alata have not been conducted, to the best of our knowledge. To address these concerns, we explored the anti-inflammatory effects of a methanol extract of T. alata (MTA) in macrophages. Non-cytotoxic concentrations of MTA (≤300 µg/ml) inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)‑stimulated RAW 264.7 macrophages by transcriptional regulation of inducible NO synthase in a dose-dependent manner. The expression of cyclooxygenase-2, the enzyme responsible for the production of prostaglandin E2, was unchanged by MTA at the mRNA and protein levels. MTA treatment inhibited interleukin (IL)-6 production and decreased the mRNA expression of pro‑inflammatory cytokines, including IL-6 and IL-1β. Tumor necrosis factor-α production and mRNA expression were not regulated by MTA treatment. The decreased production of inflammatory mediators by MTA was followed by the reduced phosphorylation of extracellular signal‑regulated kinase (ERK) and signal transducer and activator of transcription 3 (STAT3). MTA treatment had no effect on activity of other mitogen‑activated protein kinases (MAPKs), p38, c-Jun N-terminal kinase (JNK), and nuclear factor-κB (NF-κB). These results indicate that MTA selectively inhibits the excessive production of inflammatory mediators in LPS-stimulated murine macrophages by reducing the activity of ERK and STAT3, suggesting that MTA plays an important inhibitory role in the modulation of severe inflammation.

Corynoxeine isolated from the hook of Uncaria rhynchophylla inhibits rat aortic vascular smooth muscle cell proliferation through the blocking of extracellular signal regulated kinase 1/2 phosphorylation.

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Kim, Tack-Joong; Lee, Ju-Hyun; Lee, Jung-Jin; Yu, Ji-Yeon; Hwang, Bang-Yeon; Ye, Sang-Kyu; Shujuan, Li; Gao, Li; Pyo, Myoung-Yun; Yun, Yeo-Pyo

2008-11-01

The proliferation of vascular smooth muscle cells (VSMCs) induced by injury to the intima of arteries is an important etiologic factor in vascular proliferative disorders such as atherosclerosis and restenosis. Uncaria rhynchophylla is traditional Chinese herb that has been applied to the treatment of convulsive disorders, such as epilepsy, in China. In the present study, we examined whether corynoxeine exerts inhibitory effects on platelet-derived growth factor (PDGF)-BB-induced rat aortic VSMC proliferation and the possible mechanism of such effects. Pre-treatment of VSMCs with corynoxeine (5-50 microM) for 24 h resulted in significant decreases in cell number without any cytotoxicity; the inhibition percentages were 25.0+/-12.5, 63.0+/-27.5 and 88.0+/-12.5% at 5, 20 and 50 microM, respectively. Also, corynoxeine significantly inhibited the 50 ng/ml PDGF-BB-induced DNA synthesis of VSMCs in a concentration-dependent manner without any cytotoxicity; the inhibitions were 32.8+/-11.0, 51.8+/-8.0 and 76.9+/-7.4% at concentrations of 5, 20 and 50 microM, respectively. Pre-incubation of VSMCs with corynoxeine significantly inhibited PDGF-BB-induced extracellular signal-regulated kinase 1/2 (ERK1/2) activation, whereas corynoxeine had no effects on mitogen-activated protein kinase (MAPK/ERK)-activating kinase 1 and 2 (MEK1/2), Akt, or phospholipase C (PLC)gamma1 activation or on PDGF receptor beta (PDGF-Rbeta) phosphorylation. These results suggest that corynoxeine is a potent ERK1/2 inhibitor of key PDGF-BB-induced VSMC proliferation and may be useful in the prevention and treatment of vascular diseases and restenosis after angioplasty.

Protein kinase A-mediated cell proliferation in brown preadipocytes is independent of Erk1/2, PI{sub 3}K and mTOR

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Wang, Yanling; Sato, Masaaki; Guo, Yuan; Bengtsson, Tore; Nedergaard, Jan, E-mail: jan@metabol.su.se

2014-10-15

The physiological agonist norepinephrine promotes cell proliferation of brown preadipocytes during the process of tissue recruitment. In a primary culture system, cAMP mediates these adrenergic effects. In the present study, we demonstrated that, in contrast to other systems where the mitogenic effect of cAMP requires the synergistic action of (serum) growth factors, especially insulin/IGF, the cAMP effect in brown preadipocytes was independent of serum and insulin. Protein kinase A, rather than Epac, mediated the cAMP mitogenic effect. The Erk 1/2 family of MAPK, the PI{sub 3}K system and the mTOR complexes were all activated by cAMP, but these activations were not necessary for cAMP-induced cell proliferation; a protein kinase C isoform may be involved in mediating cAMP-activated cell proliferation. We conclude that the generally acknowledged cellular mediators for induction of cell proliferation are not involved in this process in the brown preadipocyte system; this conclusion may be of relevance both for examination of mechanisms for induction of brown adipose tissue recruitment but also for understanding the mechanism behind e.g. certain endocrine neoplasias. - Highlights: • cAMP can mimick norepinephrine-induced proliferation of brown preadipocytes. • The cAMP-induced proliferation can occur in the absence of serum, of any other growth factors, and of insulin. • Erk1/2, PI{sub 3}K and mTOR are cAMP activated but not involved in induction of proliferation. • A Protein Kinase C member may be in the signalling cascade. • This pathway analysis may also be of importance for certain endocrine hyper- and neoplasias.

Spontaneous chondroma formation in CD2-Cre-driven Erk-deficient mice.

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Shiokawa, Moe; Lu, Xiuyuan; Miyake, Yasunobu; Ishikawa, Eri; Pagès, Gilles; Pouysségur, Jacques; Ogata, Masato; Yamasaki, Sho

2017-12-18

Lineage-specific Cre Tg mice are widely used to delineate the functions of genes in a tissue-specific manner. Several T-cell-specific promoter cassettes have been developed; however, the activities of those promoters in non-T cells have not been investigated extensively. Here, we report that CD2-Cre-mediated deletion of Erk proteins by generating CD2-Cre × Erk1-/-Erk2flox/flox (Erk∆CD2-Cre) mice results in abnormal cartilage hyperplasia. Histological analysis revealed that this abnormality is caused by aberrant hyperplasia of chondrocytes. The presence of Erk-deficient T cells is not required for this chondroma formation, as it was similarly observed in the absence of T cells in a CD3ε-deficient background. In addition, adoptive transfer of bone marrow cells from Erk∆CD2-Cre mice to wild-type recipients did not cause chondroma formation, suggesting that Erk-deficient non-immune cells are responsible for this abnormality. By tracing Cre-expressed tissues using a ROSA26-STOP-RFP allele, we found that the chondroma emitted RFP fluorescence, indicating that functional Cre is expressed in hyperplastic chondrocytes in Erk∆CD2-Cre mice. Furthermore, RFP+ chondrocytes were also found in an Erk-sufficient background, albeit without aberrant growth. These results suggest that unexpected expression of CD2-driven Cre in chondrocytes generates Erk-deficient chondrocytes, resulting in hyperplastic cartilage formation. Recently, two independent reports showed that CD4-Cre-mediated Ras-Erk signaling ablation led to similar abnormal cartilage formation (Guittard, G., Gallardo, D. L., Li, W. et al. 2017. Unexpected cartilage phenotype in CD4-Cre-conditional SOS-deficient mice. Front. Immunol. 8:343; Wehenkel, M., Corr, M., Guy, C. S. et al. 2017. Extracellular signal-regulated kinase signaling in CD4-expressing cells inhibits osteochondromas. Front. Immunol. 8:482). Together with these reports, our study suggests that an unexpected link exists between T-like cell and

Phospho-kinase profile of triple negative breast cancer and androgen receptor signaling

International Nuclear Information System (INIS)

Cuenca-López, María D; Montero, Juan C; Morales, Jorge C; Prat, Aleix; Pandiella, Atanasio; Ocana, Alberto

2014-01-01

The androgen receptor (AR) plays a central role in the oncogenesis of different tumors, as is the case in prostate cancer. In triple negative breast cancer (TNBC) a gene expression classification has described different subgroups including a luminal androgen subtype. The AR can be controlled by several mechanisms like the activation of membrane tyrosine kinases and downstream signaling pathways. However little is known in TNBC about how the AR is modulated by these mechanisms and the potential therapeutic strategists to inhibit its expression. We used human samples to evaluate the expression of AR by western-blot and phospho-proteomic kinase arrays that recognize membrane tyrosine kinase receptors and downstream mediators. Western-blots in human cell lines were carried out to analyze the expression and activation of individual proteins. Drugs against these kinases in different conditions were used to measure the expression of the androgen receptor. PCR experiments were performed to assess changes in the AR gene after therapeutic modulation of these pathways. AR is present in a subset of TNBC and its expression correlates with activated membrane receptor kinases-EGFR and PDGFRβ in human samples and cell lines. Inhibition of the PI3K/mTOR pathway in TNBC cell lines decreased notably the expression of the AR. Concomitant administration of the anti-androgen bicalutamide with the EGFR, PDGFRβ and Erk1/2 inhibitors, decreased the amount of AR compared to each agent given alone, and had an additive anti-proliferative effect. Administration of dihydrotestosterone augmented the expression of AR that was not modified by the inhibition of the PI3K/mTOR or Erk1/2 pathways. AR expression was posttranscriptionally regulated by PI3K or Erk1/2 inhibition. Our results describe the expression of the AR in TNBC as a druggable target and further suggest the combination of bicalutamide with inhibitors of EGFR, PDGFRβ or Erk1/2 for future development

Diacylglycerol kinase β knockout mice exhibit attention-deficit behavior and an abnormal response on methylphenidate-induced hyperactivity.

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Mitsue Ishisaka

Full Text Available BACKGROUND: Diacylglycerol kinase (DGK is an enzyme that phosphorylates diacylglycerol to produce phosphatidic acid. DGKβ is one of the subtypes of the DGK family and regulates many intracellular signaling pathways in the central nervous system. Previously, we demonstrated that DGKβ knockout (KO mice showed various dysfunctions of higher brain function, such as cognitive impairment (with lower spine density, hyperactivity, reduced anxiety, and careless behavior. In the present study, we conducted further tests on DGKβ KO mice in order to investigate the function of DGKβ in the central nervous system, especially in the pathophysiology of attention deficit hyperactivity disorder (ADHD. METHODOLOGY/PRINCIPAL FINDINGS: DGKβ KO mice showed attention-deficit behavior in the object-based attention test and it was ameliorated by methylphenidate (MPH, 30 mg/kg, i.p.. In the open field test, DGKβ KO mice displayed a decreased response to the locomotor stimulating effects of MPH (30 mg/kg, i.p., but showed a similar response to an N-methyl-d-aspartate (NMDA receptor antagonist, MK-801 (0.3 mg/kg, i.p., when compared to WT mice. Examination of the phosphorylation of extracellular signal-regulated kinase (ERK, which is involved in regulation of locomotor activity, indicated that ERK1/2 activation induced by MPH treatment was defective in the striatum of DGKβ KO mice. CONCLUSIONS/SIGNIFICANCE: These findings suggest that DGKβ KO mice showed attention-deficit and hyperactive phenotype, similar to ADHD. Furthermore, the hyporesponsiveness of DGKβ KO mice to MPH was due to dysregulation of ERK phosphorylation, and that DGKβ has a pivotal involvement in ERK regulation in the striatum.

Inhibition of Melanogenesis by Gallic Acid: Possible Involvement of the PI3K/Akt, MEK/ERK and Wnt/β-Catenin Signaling Pathways in B16F10 Cells

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Su, Tzu-Rong; Lin, Jen-Jie; Tsai, Chi-Chu; Huang, Tsu-Kei; Yang, Zih-Yan; Wu, Ming-O; Zheng, Yu-Qing; Su, Ching-Chyuan; Wu, Yu-Jen

2013-01-01

Gallic acid is one of the major flavonoids found in plants. It acts as an antioxidant, and seems to have anti-inflammatory, anti-viral, and anti-cancer properties. In this study, we investigated the effects of gallic acid on melanogenesis, including the activation of melanogenesis signaling pathways. Gallic acid significantly inhibited both melanin synthesis and tyrosinase activity in a dose- and time-dependent manner, and decreased the expression of melanogenesis-related proteins, such as microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein-1 (TRP1), and dopachrome tautomerase (Dct). In addition, gallic acid also acts by phosphorylating and activating melanogenesis inhibitory proteins such as Akt and mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK). Using inhibitors against PI3K/Akt (LY294002) or MEK/ERK-specific (PD98059), the hypopigmentation effect was suppressed, and the gallic acid-initiated activation of MEK/ERK and PI3K/Akt was also revoked. Gallic acid also increased GSK3β and p-β-catenin expression but down-regulated p-GSK3β. Moreover, GSK3β-specific inhibitor (SB216763) restored gallic acid-induced melanin reduction. These results suggest that activation of the MEK/ERK, PI3K/Akt, and inhibition of Wnt/β-catenin signaling pathways is involved in the melanogenesis signaling cascade, and that activation by gallic acid reduces melanin synthesis via down-regulation of MITF and its downstream signaling pathway. In conclusion, gallic acid may be a potentially agent for the treatment of certain skin conditions. PMID:24129178

Inhibition of Melanogenesis by Gallic Acid: Possible Involvement of the PI3K/Akt, MEK/ERK and Wnt/β-Catenin Signaling Pathways in B16F10 Cells

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Yu-Jen Wu

2013-10-01

Full Text Available Gallic acid is one of the major flavonoids found in plants. It acts as an antioxidant, and seems to have anti-inflammatory, anti-viral, and anti-cancer properties. In this study, we investigated the effects of gallic acid on melanogenesis, including the activation of melanogenesis signaling pathways. Gallic acid significantly inhibited both melanin synthesis and tyrosinase activity in a dose- and time-dependent manner, and decreased the expression of melanogenesis-related proteins, such as microphthalmia-associated transcription factor (MITF, tyrosinase, tyrosinase-related protein-1 (TRP1, and dopachrome tautomerase (Dct. In addition, gallic acid also acts by phosphorylating and activating melanogenesis inhibitory proteins such as Akt and mitogen-activated protein kinase (MEK/extracellular signal-regulated kinase (ERK. Using inhibitors against PI3K/Akt (LY294002 or MEK/ERK-specific (PD98059, the hypopigmentation effect was suppressed, and the gallic acid-initiated activation of MEK/ERK and PI3K/Akt was also revoked. Gallic acid also increased GSK3β and p-β-catenin expression but down-regulated p-GSK3β. Moreover, GSK3β-specific inhibitor (SB216763 restored gallic acid-induced melanin reduction. These results suggest that activation of the MEK/ERK, PI3K/Akt, and inhibition of Wnt/β-catenin signaling pathways is involved in the melanogenesis signaling cascade, and that activation by gallic acid reduces melanin synthesis via down-regulation of MITF and its downstream signaling pathway. In conclusion, gallic acid may be a potentially agent for the treatment of certain skin conditions.

Protein kinase Cepsilon is important for migration of neuroblastoma cells

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Stensman, Helena; Larsson, Christer

2008-01-01

Migration is important for the metastatic capacity and thus for the malignancy of cancer cells. There is limited knowledge on regulatory factors that promote the migration of neuroblastoma cells. This study investigates the hypothesis that protein kinase C (PKC) isoforms regulate neuroblastoma cell motility. PKC isoforms were downregulated with siRNA or modulated with activators and inhibitors. Migration was analyzed with scratch and transwell assays. Protein phosphorylation and expression levels were measured with Western blot. Stimulation with 12-O-tetradecanoylphorbol-13-acetate (TPA) induced migration of SK-N-BE(2)C neuroblastoma cells. Treatment with the general protein kinase C (PKC) inhibitor GF109203X and the inhibitor of classical isoforms Gö6976 inhibited migration while an inhibitor of PKCβ isoforms did not have an effect. Downregulation of PKCε, but not of PKCα or PKCδ, with siRNA led to a suppression of both basal and TPA-stimulated migration. Experiments using PD98059 and LY294002, inhibitors of the Erk and phosphatidylinositol 3-kinase (PI3K) pathways, respectively, showed that PI3K is not necessary for TPA-induced migration. The Erk pathway might be involved in TPA-induced migration but not in migration driven by PKCε. TPA induced phosphorylation of the PKC substrate myristoylated alanine-rich C kinase substrate (MARCKS) which was suppressed by the PKC inhibitors. Treatment with siRNA oligonucleotides against different PKC isoforms before stimulation with TPA did not influence the phosphorylation of MARCKS. PKCε is important for migration of SK-N-BE(2)C neuroblastoma cells. Neither the Erk pathway nor MARCKS are critical downstream targets of PKCε but they may be involved in TPA-mediated migration

Low-level shear stress promotes migration of liver cancer stem cells via the FAK-ERK1/2 signalling pathway.

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Sun, Jinghui; Luo, Qing; Liu, Lingling; Song, Guanbin

2018-07-28

Cancer stem cells (CSCs) are a small subpopulation of tumour cells that have been proposed to be responsible for cancer initiation, chemotherapy resistance and cancer recurrence. Shear stress activated cellular signalling is involved in cellular migration, proliferation and differentiation. However, little is known about the effects of shear stress on the migration of liver cancer stem cells (LCSCs). Here, we studied the effects of shear stress that are generated from a parallel plated flow chamber system, on LCSC migration and the activation of focal adhesion kinase (FAK) and extracellular signal regulated kinase1/2 (ERK1/2), using transwell assay and western blot, respectively. We found that 2 dyne/cm 2 shear stress loading for 6 h promotes LCSC migration and activation of the FAK and ERK1/2 signalling pathways, whereas treatment with the FAK phosphorylation inhibitor PF573228 or the ERK1/2 phosphorylation inhibitor PD98059 suppressed the shear stress-promoted migration, indicating the involvement of FAK and ERK1/2 activation in shear stress-induced LCSC migration. Additionally, atomic force microscopy (AFM) analysis showed that shear stress lowers LCSC stiffness via the FAK and ERK1/2 pathways, suggesting that the mechanism by which shear stress promotes LCSC migration might partially be responsible for the decrease in cell stiffness. Further experiments focused on the role of the actin cytoskeleton, demonstrating that the F-actin filaments in LCSCs are less well-defined after shear stress treatment, providing an explanation for the reduction in cell stiffness and the promotion of cell migration. Overall, our study demonstrates that shear stress promotes LCSC migration through the activation of the FAK-ERK1/2 signalling pathways, which further results in a reduction of organized actin and softer cell bodies. Copyright © 2018 Elsevier B.V. All rights reserved.

Native and reconstituted HDL activate Stat3 in ventricular cardiomyocytes via ERK1/2: role of sphingosine-1-phosphate.

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Frias, Miguel A; James, Richard W; Gerber-Wicht, Christine; Lang, Ursula

2009-05-01

High-density lipoprotein (HDL) has been reported to have cardioprotective properties independent from its cholesterol transport activity. The influence of native HDL and reconstituted HDL (rHDL) on Stat3, the transcription factor playing an important role in myocardium adaptation to stress, was analysed in neonatal rat ventricular cardiomyocytes. We have investigated modulating the composition of rHDL as a means of expanding its function and potential cardioprotective effects. Stat3 phosphorylation and activation were determined by western blotting and electrophoretic mobility shift assay (EMSA). In ventricular cardiomyocytes, HDL and the HDL constituent sphingosine-1-phosphate (S1P) induce a concentration- and time-dependent increase in Stat3 activation. They also enhance extracellular signal-regulated kinases (ERK1/2) and p38 mitogen-activated protein kinase (MAPK) phosphorylation. U0126, a specific inhibitor of MEK1/2, the upstream activator of ERK1/2, abolishes HDL- and S1P-induced Stat3 activation, whereas the p38 MAPK blocker SB203580 has no significant effect. Inhibition of the tyrosine kinase family Src (Src) caused a significant reduction of Stat3 activation, whereas inhibition of phosphatidylinositol 3-kinase (PI3K) had no effect. S1P and rHDL containing S1P have a similar strong stimulatory action on Stat3, ERK1/2, and p38 MAPK comparable to native HDL. S1P-free rHDL has a much weaker effect. Experiments with agonists and antagonists of the S1P receptor subtypes indicate that HDL and S1P activate Stat3 mainly through the S1P2 receptor. In ventricular cardiomyocytes, addition of S1P to rHDL enhances its therapeutic potential by improving its capacity to activate Stat3. Activation of Stat3 occurs mainly via the S1P constituent and the lipid receptor S1P2 requiring stimulation of ERK1/2 and Src but not p38 MAPK or PI3K. The study underlines the therapeutic potential of tailoring rHDL to confront particular clinical situations.

Resveratrol prevents high glucose-induced epithelial-mesenchymal transition in renal tubular epithelial cells by inhibiting NADPH oxidase/ROS/ERK pathway.

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He, Ting; Guan, Xu; Wang, Song; Xiao, Tangli; Yang, Ke; Xu, Xinli; Wang, Junping; Zhao, Jinghong

2015-02-15

Resveratrol (RSV) is reported to have renoprotective activity against diabetic nephropathy, while the mechanisms underlying its function have not been fully elucidated. In this study, we investigate the effect and related mechanism of RSV against high glucose-induced epithelial to mesenchymal transition (EMT) in human tubular epithelial cells (HK-2). A typical EMT is induced by high glucose in HK-2 cells, accompanied by increased levels of reactive oxygen species (ROS). RSV exhibits a strong ability to inhibit high glucose-induced EMT by decreasing intracellular ROS levels via down-regulation of NADPH oxidase subunits NOX1 and NOX4. The activation of extracellular signal-regulated kinase (ERK1/2) is found to be involved in high glucose-induced EMT in HK-2 cells. RSV, like NADPH oxidase inhibitor diphenyleneiodonium, can block ERK1/2 activation induced by high glucose. Our results demonstrate that RSV is a potent agent against high glucose-induced EMT in renal tubular cells via inhibition of NADPH oxidase/ROS/ERK1/2 pathway. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Prohibitin (PHB) inhibits apoptosis in rat granulosa cells (GCs) through the extracellular signal-regulated kinase 1/2 (ERK1/2) and the Bcl family of proteins.

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Chowdhury, Indrajit; Thompson, Winston E; Welch, Crystal; Thomas, Kelwyn; Matthews, Roland

2013-12-01

Mammalian ovarian follicular development is tightly regulated by crosstalk between cell death and survival signals, which include both endocrine and intra-ovarian regulators. Whether the follicle ultimately ovulates or undergoes atresia is dependent on the expression and actions of factors promoting follicular cell proliferation, differentiation or apoptosis. Prohibitin (PHB) is a highly conserved, ubiquitous protein that is abundantly expressed in granulosa cells (GCs) and associated with GC differentiation and apoptosis. The current study was designed to characterize the regulation of anti-apoptotic and pro-apoptotic factors in undifferentiated rat GCs (gonadotropin independent phase) governed by PHB. Microarray technology was initially employed to identify potential apoptosis-related genes, whose expression levels within GCs were altered by either staurosporine (STS) alone or STS in presence of ectopically over-expressed PHB. Next, immunoblot studies were performed to examine the expression patterns of selective Bcl-2 family members identified by the microarray analysis, which are commonly regulated in the intrinsic-apoptotic pathway. These studies were designed to measure protein levels of Bcl2 family in relation to expression of the acidic isoform (phosphorylated) PHB and the components of MEK-Erk1/2 pathway. These studies indicated that over-expression of PHB in undifferentiated GCs inhibit apoptosis which concomitantly results in an increased level of the anti-apoptotic proteins Bcl2 and Bclxl, reduced release of cytochrome c from mitochondria and inhibition of caspase-3 activity. In contrast, silencing of PHB expression resulted in change of mitochondrial morphology from the regular reticular network to a fragmented form, which enhanced sensitization of these GCs to the induction of apoptosis. Collectively, these studies have provided new insights on the PHB-mediated anti-apoptotic mechanism, which occurs in undifferentiated GCs through a PHB → Mek-Erk1

Sphingosine kinase-1 mediates androgen-induced osteoblast cell growth

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Martin, Claire [CNRS, Institut de Pharmacologie et de Biologie Structurale, Toulouse F-31000 (France); Universite de Toulouse, UPS, IPBS, Toulouse F-31000 (France); Lafosse, Jean-Michel [CHU Toulouse, Hopital Rangueil, Service d' orthopedie et Traumatologie, Toulouse F-31000 (France); Malavaud, Bernard [CNRS, Institut de Pharmacologie et de Biologie Structurale, Toulouse F-31000 (France); Universite de Toulouse, UPS, IPBS, Toulouse F-31000 (France); CHU Toulouse, Hopital Rangueil, Service d' Urologie et de Transplantation Renale, Toulouse F-31000 (France); Cuvillier, Olivier, E-mail: olivier.cuvillier@ipbs.fr [CNRS, Institut de Pharmacologie et de Biologie Structurale, Toulouse F-31000 (France); Universite de Toulouse, UPS, IPBS, Toulouse F-31000 (France)

2010-01-01

Herein we report that the lipid kinase sphingosine kinase-1 (SphK1) is instrumental in mediating androgen-induced cell proliferation in osteoblasts. Dihydrotestosterone (DHT) triggered cell growth in steroid-deprived MC3T3 cells, which was associated with a rapid stimulation of SphK1 and activation of both Akt and ERK signaling pathways. This mechanism relied on functional androgen receptor/PI3K/Akt nongenotropic signaling as pharmacological antagonists could block SphK1 stimulation by DHT and its consequences. Finally, SphK1 inhibition not only abrogated DHT-induced ERK activation but also blocked cell proliferation, while ERK inhibition had no impact, suggesting that SphK1 was critical for DHT signaling yet independently of the ERK.

Posttranscriptional Regulation of Cyclooxygenase-2 in Rat Intestinal Epithelial Cells

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Zhonghua Zhang

2000-01-01

Full Text Available Modulation of cyclooxygenase-2 (COX-2 mRNA stability plays an important role in the regulation of its expression by oncogenic Ras. Here, we evaluate COX-2 mRNA stability in response to treatment with two known endogenous promoters of gastrointestinal cancer, the bile acid (chenodeoxycholate; CD and ceramide. Treatment with CD and ceramide resulted in a 10-fold increase in the level of COX-2 protein and a four-fold lengthening of the half-life of COX-2 mRNA. COX-2 mRNA stability was assessed by Northern blot analysis and by evaluating the AU-rich element located in the COX-2 3′-UTR. A known inhibitor of mitogen-activated protein (MAP/extracellular signal-regulated kinase (ERK kinase (MEK, PD98059, reversed the effects of CD or ceramide to stabilize COX-2 mRNA. Overexpression of a dominant-negative ERK-1 or ERK-2 protein also led to destabilization of COX-2 mRNA. Treatment with a p38 MAPK inhibitor, PD169316, or transfection with a dominant-negative p38 MAPK construct reversed the effect of CD or ceramide to stabilize COX-2 mRNA. Expression of a dominant-negative c-Jun N-terminal kinase (JNK had no effect on COX-2 mRNA stability in cells treated with CD or ceramide. We conclude that posttranscriptional mechanisms play an important role in the regulation of COX-2 expression during carcinogenesis.

Long-term potentiation in the CA1 hippocampus induced by NR2A subunit-containing NMDA glutamate receptors is mediated by Ras-GRF2/Erk map kinase signaling.

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Shan-xue Jin

Full Text Available BACKGROUND: NMDA-type glutamate receptors (NMDARs are major contributors to long-term potentiation (LTP, a form of synaptic plasticity implicated in the process of learning and memory. These receptors consist of calcium-permeating NR1 and multiple regulatory NR2 subunits. A majority of studies show that both NR2A and NR2B-containing NMDARs can contribute to LTP, but their unique contributions to this form of synaptic plasticity remain poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we show that NR2A and NR2B-containing receptors promote LTP differently in the CA1 hippocampus of 1-month old mice, with the NR2A receptors functioning through Ras-GRF2 and its downstream effector, Erk Map kinase, and NR2B receptors functioning independently of these signaling molecules. CONCLUSIONS/SIGNIFICANCE: This study demonstrates that NR2A-, but not NR2B, containing NMDA receptors induce LTP in pyramidal neurons of the CA1 hippocampus from 1 month old mice through Ras-GRF2 and Erk. This difference add new significance to the observation that the relative levels of these NMDAR subtypes is regulated in neurons, such that NR2A-containing receptors become more prominent late in postnatal development, after sensory experience and synaptic activity.

Protein kinase activity of phosphoinositide 3-kinase regulates cytokine-dependent cell survival.

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Daniel Thomas

Full Text Available The dual specificity protein/lipid kinase, phosphoinositide 3-kinase (PI3K, promotes growth factor-mediated cell survival and is frequently deregulated in cancer. However, in contrast to canonical lipid-kinase functions, the role of PI3K protein kinase activity in regulating cell survival is unknown. We have employed a novel approach to purify and pharmacologically profile protein kinases from primary human acute myeloid leukemia (AML cells that phosphorylate serine residues in the cytoplasmic portion of cytokine receptors to promote hemopoietic cell survival. We have isolated a kinase activity that is able to directly phosphorylate Ser585 in the cytoplasmic domain of the interleukin 3 (IL-3 and granulocyte macrophage colony stimulating factor (GM-CSF receptors and shown it to be PI3K. Physiological concentrations of cytokine in the picomolar range were sufficient for activating the protein kinase activity of PI3K leading to Ser585 phosphorylation and hemopoietic cell survival but did not activate PI3K lipid kinase signaling or promote proliferation. Blockade of PI3K lipid signaling by expression of the pleckstrin homology of Akt1 had no significant impact on the ability of picomolar concentrations of cytokine to promote hemopoietic cell survival. Furthermore, inducible expression of a mutant form of PI3K that is defective in lipid kinase activity but retains protein kinase activity was able to promote Ser585 phosphorylation and hemopoietic cell survival in the absence of cytokine. Blockade of p110α by RNA interference or multiple independent PI3K inhibitors not only blocked Ser585 phosphorylation in cytokine-dependent cells and primary human AML blasts, but also resulted in a block in survival signaling and cell death. Our findings demonstrate a new role for the protein kinase activity of PI3K in phosphorylating the cytoplasmic tail of the GM-CSF and IL-3 receptors to selectively regulate cell survival highlighting the importance of targeting

Effects of protein kinase C activators on phorbol ester-sensitive and -resistant EL4 thymoma cells.

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Sansbury, H M; Wisehart-Johnson, A E; Qi, C; Fulwood, S; Meier, K E

1997-09-01

Phorbol ester-sensitive EL4 murine thymoma cells respond to phorbol 12-myristate 13-acetate with activation of ERK mitogen-activated protein kinases, synthesis of interleukin-2, and death, whereas phorbol ester-resistant variants of this cell line do not exhibit these responses. Additional aspects of the resistant phenotype were examined, using a newly-established resistant cell line. Phorbol ester induced morphological changes, ERK activation, calcium-dependent activation of the c-Jun N-terminal kinase (JNK), interleukin-2 synthesis, and growth inhibition in sensitive but not resistant cells. A series of protein kinase C activators caused membrane translocation of protein kinase C's (PKCs) alpha, eta, and theta in both cell lines. While PKC eta was expressed at higher levels in sensitive than in resistant cells, overexpression of PKC eta did not restore phorbol ester-induced ERK activation to resistant cells. In sensitive cells, PKC activators had similar effects on cell viability and ERK activation, but differed in their abilities to induce JNK activation and interleukin-2 synthesis. PD 098059, an inhibitor of the mitogen activated protein (MAP)/ERK kinase kinase MEK, partially inhibited ERK activation and completely blocked phorbol ester-induced cell death in sensitive cells. Thus MEK and/or ERK activation, but not JNK activation or interleukin-2 synthesis, appears to be required for phorbol ester-induced toxicity. Alterations in phorbol ester response pathways, rather than altered expression of PKC isoforms, appear to confer phorbol ester resistance to EL4 cells.

Viral exploitation of the MEK/ERK pathway - A tale of vaccinia virus and other viruses.

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Bonjardim, Cláudio A

2017-07-01

The VACV replication cycle is remarkable in the sense that it is performed entirely in the cytoplasmic compartment of vertebrate cells, due to its capability to encode enzymes required either for regulating the macromolecular precursor pool or the biosynthetic processes. Although remarkable, this gene repertoire is not sufficient to confer the status of a free-living microorganism to the virus, and, consequently, the virus relies heavily on the host to successfully generate its progeny. During the complex virus-host interaction, viruses must deal not only with the host pathways to accomplish their temporal demands but also with pathways that counteract viral infection, including the inflammatory, innate and acquired immune responses. This review focuses on VACV and other DNA or RNA viruses that stimulate the MEK (MAPK - Mitogen Activated Protein Kinase)/ERK- Extracellular signal-Regulated Kinase) pathway as part of their replication cycle. Copyright © 2016 Elsevier Inc. All rights reserved.

Kaempferol Inhibits Angiogenesis by Suppressing HIF-1α and VEGFR2 Activation via ERK/p38 MAPK and PI3K/Akt/mTOR Signaling Pathways in Endothelial Cells.

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Kim, Gi Dae

2017-12-01

Kaempferol has been shown to inhibit vascular formation in endothelial cells. However, the underlying mechanisms are not fully understood. In the present study, we evaluated whether kaempferol exerts antiangiogenic effects by targeting extracellular signal-regulated kinase (ERK)/p38 mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR) signaling pathways in endothelial cells. Endothelial cells were treated with various concentrations of kaempferol for 24 h. Cell viability was determined by the 3- (4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay; vascular formation was analyzed by tube formation, wound healing, and mouse aortic ring assays. Activation of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor receptor 2 (VEGFR2), ERK/p38 MAPK, and PI3K/Akt/mTOR was analyzed by Western blotting. Kaempferol significantly inhibited cell migration and tube formation in endothelial cells, and suppressed microvessel sprouting in the mouse aortic ring assay. Moreover, kaempferol suppressed the activation of HIF-1α, VEGFR2, and other markers of ERK/p38 MAPK and PI3K/Akt/mTOR signaling pathways in endothelial cells. These results suggest that kaempferol inhibits angiogenesis by suppressing HIF-1α and VEGFR2 activation via ERK/p38 MAPK and PI3K/Akt/mTOR signaling in endothelial cells.

ERK inhibition promotes neuroectodermal precursor commitment by blocking self-renewal and primitive streak formation of the epiblast.

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Yu, Yang; Wang, Xiaoxiao; Zhang, Xiaoxin; Zhai, Yanhua; Lu, Xukun; Ma, Haixia; Zhu, Kai; Zhao, Tongbiao; Jiao, Jianwei; Zhao, Zhen-Ao; Li, Lei

2018-01-05

Pluripotent stem cells hold great promise for regenerative medicine. However, before clinical application, reproducible protocols for pluripotent stem cell differentiation should be established. Extracellular signal-regulated protein kinase (ERK) signaling plays a central role for the self-renewal of epiblast stem cells (EpiSCs), but its role for subsequent germ layer differentiation is still ambiguous. We proposed that ERK could modulate differentiation of the epiblast. PD0325901 was used to inhibit ERK activation during the differentiation of embryonic stem cells and EpiSCs. Immunofluorescence, western blot analysis, real-time PCR and flow cytometry were used to detect germ layer markers and pathway activation. We demonstrate that the ERK phosphorylation level is lower in neuroectoderm of mouse E7.5 embryos than that in the primitive streak. ERK inhibition results in neural lineage commitment of epiblast. Mechanistically, PD0325901 abrogates the expression of primitive streak markers by β-catenin retention in the cytoplasm, and inhibits the expression of OCT4 and NANOG during EpiSC differentiation. Thus, EpiSCs differentiate into neuroectodermal lineage efficiently under PD0325901 treatment. These results suggest that neuroectoderm differentiation does not require extrinsic signals, supporting the default differentiation of neural lineage. We report that a single ERK inhibitor, PD0325901, can specify epiblasts and EpiSCs into neural-like cells, providing an efficient strategy for neural differentiation.

Lipo-PGE1 suppresses collagen production in human dermal fibroblasts via the ERK/Ets-1 signaling pathway.

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Yoolhee Yang

Full Text Available Dysregulation of collagen production contributes to various pathological processes, including tissue fibrosis as well as impaired wound healing. Lipo-prostaglandin E1 (Lipo-PGE1, a lipid microsphere-incorporated prostaglandin E1, is used as a vasodilator for the treatment of peripheral vascular diseases. Lipo-PGE1 was recently shown to enhance human dermal fibroblast (HDF migration and in vivo wound healing. No published study has characterized the role of Lipo-PGE1 in collagen regulation in HDFs. Here, we investigated the cellular signaling mechanism by which Lipo-PGE1 regulates collagen in HDFs. Collagen production was evaluated by the Sircol collagen assay, Western blot analysis of type I collagen and real time PCR. Unexpectedly, Lipo-PGE1 decreased mRNA expression of collagen 1A1, 1A2, and 3A1. Lipo-PGE1 markedly inhibited type I collagen and total soluble collagen production. In addition, Lipo-PGE1 inhibited transforming growth factor-β-induced collagen expression via Smad2 phosphorylation. To further investigate whether extracellular signal-regulated kinase (ERK/Ets-1 signaling, a crucial pathway in collagen regulation, is involved in Lipo-PGE1-inhibited collagen production, cells were pretreated with an ERK-specific inhibitor, PD98059, prior to the addition of Lipo-PGE1. Lipo-PGE1-inhibited collagen mRNA expression and total soluble collagen production were recovered by pretreatment with PD98059. Moreover, Lipo-PGE1 directly induced the phosphorylation of ERK. Furthermore, silencing of Ets-1 recovered Lipo-PGE1-inhibited collagen production and PD98059 blocked Lipo-PGE1-enhanced Ets-1 expression. The present study reveals an important role for Lipo-PGE1 as a negative regulator of collagen gene expression and production via ERK/Ets-1 signaling. These results suggest that Lipo-PGE1 could potentially be a therapeutic target in diseases with deregulated collagen turnover.

Metallothionein-III protects against 6-hydroxydopamine-induced oxidative stress by increasing expression of heme oxygenase-1 in a PI3K and ERK/Nrf2-dependent manner

International Nuclear Information System (INIS)

Hwang, Yong Pil; Kim, Hyung Gyun; Han, Eun Hee; Jeong, Hye Gwang

2008-01-01

The zinc-binding protein metallothionein-III (MT-III) is associated with resistance to neuronal injury. However, the underlying mechanism for its effects is unclear. In this study, we demonstrate that MT-III prevents the accumulation of reactive oxygen species (ROS) in dopaminergic SH-SY5Y cells challenged with the Parkinson's disease-related neurotoxin 6-hydroxydopamine (6-OHDA) by a mechanism that involves phosphatidylinositol 3-kinase (PI3K) and ERK kinase/NF-E2-related factor 2 (Nrf2) dependent induction of the stress response protein heme oxygenase-1 (HO-1). Pretreatment of SH-SY5Y cells with MT-III significantly reduced 6-OHDA-induced generation of ROS, caspase-3 activation, and subsequent cell death. Also, MT-III up-regulates HO-1 expression and this expression confers neuroprotection against oxidative injury induced by 6-OHDA. Moreover, MT-III induces Nrf2 nuclear translocation, which is upstream of MT-III-induced HO-1 expression, and PI3K and ERK1/2 activation, a pathway that is involved in induced Nrf2 nuclear translocation, HO-1 expression and neuroprotection. Taken together, these results suggest that the PI3K and ERK/Nrf2 signaling pathway controls the intracellular levels of ROS by regulating the expression of the antioxidant enzyme HO-1

Regulation of PPARγ function by TNF-α

International Nuclear Information System (INIS)

Ye Jianping

2008-01-01

The nuclear receptor PPARγ is a lipid sensor that regulates lipid metabolism through gene transcription. Inhibition of PPARγ activity by TNF-α is involved in pathogenesis of insulin resistance, atherosclerosis, inflammation, and cancer cachexia. PPARγ activity is regulated by TNF-α at pre-translational and post-translational levels. Activation of serine kinases including IKK, ERK, JNK, and p38 may be involved in the TNF-regulation of PPARγ. Of the four kinases, IKK is a dominant signaling molecule in the TNF-regulation of PPARγ. IKK acts through at least two mechanisms: inhibition of PPARγ expression and activation of PPARγ corepressor. In this review article, literature is reviewed with a focus on the mechanisms of PPARγ inhibition by TNF-α

Involvement of ERK phosphorylation of trigeminal spinal subnucleus caudalis neurons in thermal hypersensitivity in rats with infraorbital nerve injury.

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Ikuko Suzuki

Full Text Available To evaluate the involvement of the mitogen-activated protein kinase (MAPK cascade in orofacial neuropathic pain mechanisms, this study assessed nocifensive behavior evoked by mechanical or thermal stimulation of the whisker pad skin, phosphorylation of extracellular signal-regulated kinase (ERK in trigeminal spinal subnucleus caudalis (Vc neurons, and Vc neuronal responses to mechanical or thermal stimulation of the whisker pad skin in rats with the chronic constriction nerve injury of the infraorbital nerve (ION-CCI. The mechanical and thermal nocifensive behavior was significantly enhanced on the side ipsilateral to the ION-CCI compared to the contralateral whisker pad or sham rats. ION-CCI rats had an increased number of phosphorylated ERK immunoreactive (pERK-IR cells which also manifested NeuN-IR but not GFAP-IR and Iba1-IR, and were significantly more in ION-CCI rats compared with sham rats following noxious but not non-noxious mechanical stimulation. After intrathecal administration of the MEK1 inhibitor PD98059 in ION-CCI rats, the number of pERK-IR cells after noxious stimulation and the enhanced thermal nocifensive behavior but not the mechanical nocifensive behavior were significantly reduced in ION-CCI rats. The enhanced background activities, afterdischarges and responses of wide dynamic range neurons to noxious mechanical and thermal stimulation in ION-CCI rats were significantly depressed following i.t. administration of PD98059, whereas responses to non-noxious mechanical and thermal stimulation were not altered. The present findings suggest that pERK-IR neurons in the Vc play a pivotal role in the development of thermal hypersensitivity in the face following trigeminal nerve injury.

The accumulations of HIF-1α and HIF-2α by JNK and ERK are involved in biphasic effects induced by different levels of arsenite in human bronchial epithelial cells

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Xu, Yuan; Li, Yuan; Li, Huiqiao; Pang, Ying; Zhao, Yue; Jiang, Rongrong; Shen, Lu; Zhou, Jianwei; Wang, Xinru; Liu, Qizhan

2013-01-01

The biphasic effects of arsenite, in which low levels of arsenite induce cell proliferation and high levels of arsenite induce DNA damage and apoptosis, apparently contribute to arsenite-induced carcinogenesis. However, the mechanisms underlying this phenomenon are not well understood. In this study, we investigated the effects of different levels of arsenite on cell proliferation, DNA damage and apoptosis as well as on signal transduction pathways in human bronchial epithelial (HBE) cells. Our results show that a low level of arsenite activates extracellular signal-regulated kinases (ERK), which probably mediate arsenite-inhibited degradation of ubiquitinated hypoxia-inducible factor-2α (HIF-2α) in HBE cells. ERK inhibition blocks cell proliferation induced by a low level of arsenite, in part via HIF-2α. In contrast, a high level of arsenite activates c-Jun N-terminal kinases (JNK), which provoke a response to suppress ubiquitinated HIF-1α degradation. Down-regulation of HIF-1α by inhibiting JNK, however, increases the DNA damage but decreases the apoptosis induced by a high level of arsenite. Thus, data in the present study suggest that the accumulations of HIF-1α and HIF-2α by JNK and ERK are involved in different levels of arsenite-induced biphasic effects, with low levels of arsenite inducing cell proliferation and high levels of arsenite inducing DNA damage and apoptosis in HBE cells. -- Highlights: ► Biphasic effects induced by different concentrations of arsenite. ► Different regulation of ERK or JNK signal pathway by arsenite. ► Different regulation of HIF1α or HIF 2α by arsenite.

Regulation of the interaction between protein kinase C-related protein kinase 2 (PRK2) and its upstream kinase, 3-phosphoinositide-dependent protein kinase 1 (PDK1)

DEFF Research Database (Denmark)

Dettori, Rosalia; Sonzogni, Silvina; Meyer, Lucas

2009-01-01

of numerous AGC kinases, including the protein kinase C-related protein kinases (PRKs). Here we studied the docking interaction between PDK1 and PRK2 and analyzed the mechanisms that regulate this interaction. In vivo labeling of recombinant PRK2 by (32)P(i) revealed phosphorylation at two sites......, the activation loop and the Z/TM in the C-terminal extension. We provide evidence that phosphorylation of the Z/TM site of PRK2 inhibits its interaction with PDK1. Our studies further provide a mechanistic model to explain different steps in the docking interaction and regulation. Interestingly, we found...... that the mechanism that negatively regulates the docking interaction of PRK2 to the upstream kinase PDK1 is directly linked to the activation mechanism of PRK2 itself. Finally, our results indicate that the mechanisms underlying the regulation of the interaction between PRK2 and PDK1 are specific for PRK2 and do...

Csk-Induced Phosphorylation of Src at Tyrosine 530 is Essential for H2O2-Mediated Suppression of ERK1/2 in Human Umbilical Vein Endothelial Cells

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Jeon, Bo Kyung; Kwon, Kihwan; Kang, Jihee Lee; Choi, Youn-Hee

2015-01-01

Mitogen-activated protein kinases (MAPKs) are key signal transducers involved in various cellular events such as growth, proliferation, and differentiation. Previous studies have reported that H2O2 leads to phosphorylation of extracellular signal-regulated kinase (ERK), one of the MAPKs in endothelial cells. The current study shows that H2O2 suppressed ERK1/2 activation and phosphorylation at specific concentrations and times in human umbilical vein endothelial cells but not in immortalized mouse aortic endothelial cells or human astrocytoma cell line CRT-MG. Phosphorylation of other MAPK family members (i.e., p38 and JNK) was not suppressed by H2O2. The decrease in ERK1/2 phosphorylation induced by H2O2 was inversely correlated with the level of phosphorylation of Src tyrosine 530. Using siRNA, it was found that H2O2-induced suppression of ERK1/2 was dependent on Csk. Physiological laminar flow abrogated, but oscillatory flow did not affect, the H2O2-induced suppression of ERK1/2 phosphorylation. In conclusion, H2O2-induced Csk translocation to the plasma membrane leads to phosphorylation of Src at the tyrosine 530 residue resulting in a reduction of ERK1/2 phosphorylation. Physiological laminar flow abrogates this effect of H2O2 by inducing phosphorylation of Src tyrosine 419. These findings broaden our understanding of signal transduction mechanisms in the endothelial cells against oxidative stress. PMID:26234813

Prelimbic cortex extracellular signal-regulated kinase 1/2 activation is required for memory retrieval of long-term inhibitory avoidance.

Science.gov (United States)

Luo, Fei; Zheng, Jian; Sun, Xuan; Deng, Wei-Ke; Li, Bao Ming; Liu, Fang

2017-04-15

Neural mechanism underlying memory retrieval has been extensively studied in the hippocampus and amygdala. However, little is known about the role of medial prefrontal cortex in long-term memory retrieval. We evaluate this issue in one-trial step-through inhibitory avoidance (IA) paradigm. Our results showed that, 1) inactivation of mPFC by local infusion of GABA A -receptor agonist muscimol caused severe deficits in retrieval of 1-day and 7-day but had no effects on 2-h inhibitory avoidance memory; 2) the protein level of phosphorylated-ERK1/2 in mPFC were significantly increased following retrieval of 1-day and 7-day IA memory, so did the numbers of phosphorylated-ERK (pERK) and phosphorylated-CREB (pCREB) labeled neurons; 3) intra-mPFC infusion of ERK kinase inhibitor PD98095 significantly reduced phosphorylated ERK1/2 levels and phosphorylated-ERK1/2 and phosphorylated-CREB labeled cells, and severely impaired retrieval of 7-day IA memory when the drugs were administrated 30min prior to test. The present study provides evidence that retrieval of long-lasting memory for inhibitory avoidance requires mPFC and involves the ERK-CREB signaling cascade. Copyright © 2017 Elsevier B.V. All rights reserved.

Oncogenic Ras-Induced Morphologic Change Is through MEK/ERK Signaling Pathway to Downregulate Stat3 at a Posttranslational Level in NIH3T3 Cells

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Hsuan-Heng Yeh

2008-01-01

Full Text Available Ras is a key regulator of the MAP kinase-signaling cascade and may cause morphologic change of Ras-transformed cells. Signal transducer and activator of transcription 3 (Stat3 can be activated by cytokine stimulation. In this study, we unravel that Ha-rasV12 overexpression can downregulate the expression of Stat3 protein at a posttranslational level in NIH3T3 cells. Furthermore, we demonstrate that Stat3 expression downregulated by Ha-rasV12 overexpression is through proteosome degradation and not through a mTOR/p70S6K-related signaling pathway. The suppression of Stat3 accompanied by the morphologic change induced by Ha-rasV12 was through mitogen extracellular kinase (MEK/extracellular-regulated kinase (ERK signaling pathway. Microtubule disruption is involved in Ha-rasV12-induced morphologic change, which could be reversed by overexpression of Stat3. Taken together, we are the first to demonstrate that Stat3 protein plays a critical role in Ha-rasV12-induced morphologic change. Oncogenic Ras-triggered morphologic change is through the activation of MEK/ERK to posttranslationally downregulate Stat3 expression. Our finding may shed light on developing novel therapeutic strategies against Ras-related tumorigenesis.

Regulation of glucose homeostasis by KSR1 and MARK2.

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Paula J Klutho

Full Text Available Protein scaffolds control the intensity and duration of signaling and dictate the specificity of signaling through MAP kinase pathways. KSR1 is a molecular scaffold of the Raf/MEK/ERK MAP kinase cascade that regulates the intensity and duration of ERK activation. Relative to wild-type mice, ksr1⁻/⁻ mice are modestly glucose intolerant, but show a normal response to exogenous insulin. However, ksr1⁻/⁻ mice also demonstrate a three-fold increase in serum insulin levels in response to a glucose challenge, suggesting a role for KSR1 in insulin secretion. The kinase MARK2 is closely related to C-TAK1, a known regulator of KSR1. Mice lacking MARK2 have an increased rate of glucose disposal in response to exogenous insulin, increased glucose tolerance, and are resistant to diet-induced obesity. mark2⁻/⁻ksr1⁻/⁻ (DKO mice were compared to wild type, mark2⁻/⁻, and ksr1⁻/⁻ mice for their ability to regulate glucose homeostasis. Here we show that disruption of KSR1 in mark2⁻/⁻ mice reverses the increased sensitivity to exogenous insulin resulting from MARK2 deletion. DKO mice respond to exogenous insulin similarly to wild type and ksr1⁻/⁻ mice. These data suggest a model whereby MARK2 negatively regulates insulin sensitivity in peripheral tissue through inhibition of KSR1. Consistent with this model, we found that MARK2 binds and phosphorylates KSR1 on Ser392. Phosphorylation of Ser392 is a critical regulator of KSR1 stability, subcellular location, and ERK activation. These data reveal an unexpected role for the molecular scaffold KSR1 in insulin-regulated glucose metabolism.

Investigation of the Flexibility of Protein Kinases Implicated in the Pathology of Alzheimer’s Disease

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Michael P. Mazanetz

2014-06-01

Full Text Available The pathological characteristics of Alzheimer’s Disease (AD have been linked to the activity of three particular kinases—Glycogen Synthase Kinase 3β (GSK3β, Cyclin-Dependent Kinase 5 (CDK5 and Extracellular-signal Regulated Kinase 2 (ERK2. As a consequence, the design of selective, potent and drug-like inhibitors of these kinases is of particular interest. Structure-based design methods are well-established in the development of kinase inhibitors. However, progress in this field is limited by the difficulty in obtaining X-ray crystal structures suitable for drug design and by the inability of this method to resolve highly flexible regions of the protein that are crucial for ligand binding. To address this issue, we have undertaken a study of human protein kinases CDK5/p25, CDK5, ERK2 and GSK3β using both conventional molecular dynamics (MD and the new Active Site Pressurisation (ASP methodology, to look for kinase-specific patterns of flexibility that could be leveraged for the design of selective inhibitors. ASP was used to examine the intrinsic flexibility of the ATP-binding pocket for CDK5/p25, CDK5 and GSK3β where it is shown to be capable of inducing significant conformational changes when compared with X-ray crystal structures. The results from these experiments were used to quantify the dynamics of each protein, which supported the observations made from the conventional MD simulations. Additional information was also derived from the ASP simulations, including the shape of the ATP-binding site and the rigidity of the ATP-binding pocket. These observations may be exploited in the design of selective inhibitors of GSK3β, CDK5 and ERK2.

Fps/Fes and Fer non-receptor protein-tyrosine kinases regulate collagen- and ADP-induced platelet aggregation.

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Senis, Y A; Sangrar, W; Zirngibl, R A; Craig, A W B; Lee, D H; Greer, P A

2003-05-01

Fps/Fes and Fer proto-oncoproteins are structurally related non-receptor protein-tyrosine kinases implicated in signaling downstream from cytokines, growth factors and immune receptors. We show that Fps/Fes and Fer are expressed in human and mouse platelets, and are activated following stimulation with collagen and collagen-related peptide (CRP), suggesting a role in GPVI receptor signaling. Fer was also activated following stimulation with thrombin and a protease-activated receptor4 (PAR4)-activating peptide, suggesting a role in signaling downstream from the G protein-coupled PAR4. There were no detectable perturbations in CRP-induced activation of Syk, PLCgamma2, cortactin, Erk, Jnk, Akt or p38 in platelets from mice lacking Fps/Fes, Fer, or both kinases. Platelets lacking Fps/Fes, from a targeted fps/fes null strain of mice, showed increased rates and amplitudes of collagen-induced aggregation, relative to wild-type platelets. P-Selectin expression was also elevated on the surface of Fps/Fes-null platelets in response to CRP. Fer-deficient platelets, from mice targeted with a kinase-inactivating mutation, disaggregated more rapidly than wild-type platelets in response to ADP. This report provides the first evidence that Fps/Fes and Fer are expressed in platelets and become activated downstream from the GPVI collagen receptor, and that Fer is activated downstream from a G-protein coupled receptor. Furthermore, using targeted mouse models we show that deficiency in Fps/Fes or Fer resulted in disregulated platelet aggregation and disaggregation, demonstrating a role for these kinases in regulating platelet functions.

Lactoferrin inhibits dexamethasone-induced chondrocyte impairment from osteoarthritic cartilage through up-regulation of extracellular signal-regulated kinase 1/2 and suppression of FASL, FAS, and Caspase 3

International Nuclear Information System (INIS)

Tu, Yihui; Xue, Huaming; Francis, Wendy; Davies, Andrew P.; Pallister, Ian; Kanamarlapudi, Venkateswarlu; Xia, Zhidao

2013-01-01

Highlights: •Dex exerts dose-dependant inhibition of HACs viability and induction of apoptosis. •Dex-induced impairment of chondrocytes was attenuated by rhLF. •ERK and FASL/FAS signaling are involved in the effects of rhLF. •OA patients with glucocorticoid-induced cartilage damage may benefit from treatment with rhLF. -- Abstract: Dexamethasone (Dex) is commonly used for osteoarthritis (OA) with excellent anti-inflammatory and analgesic effect. However, Dex also has many side effects following repeated use over prolonged periods mainly through increasing apoptosis and inhibiting proliferation. Lactoferrin (LF) exerts significantly anabolic effect on many cells and little is known about its effect on OA chondrocytes. Therefore, the aim of this study is to investigate whether LF can inhibit Dex-induced OA chondrocytes apoptosis and explore its possible molecular mechanism involved in. MTT assay was used to determine the optimal concentration of Dex and recombinant human LF (rhLF) on chondrocytes at different time and dose points. Chondrocytes were then stimulated with Dex in the absence or presence of optimal concentration of rhLF. Cell proliferation and viability were evaluated using MTT and LIVE/DEAD assay, respectively. Cell apoptosis was evaluated by multi-parameter apoptosis assay kit using both confocal microscopy and flow cytometry, respectively. The expression of extracellular signal-regulated kinase (ERK), FAS, FASL, and Caspase-3 (CASP3) at the mRNA and protein levels were examined by real-time polymerase chain reaction (PCR) and immunocytochemistry, respectively. The optimal concentration of Dex (25 μg/ml) and rhLF (200 μg/ml) were chosen for the following experiments. rhLF significantly reversed the detrimental effect of Dex on chondrocytes proliferation, viability, and apoptosis. In addition, rhLF significantly prevented Dex-induced down-regulation of ERK and up-regulation of FAS, FASL, and CASP3. These findings demonstrated that rhLF acts as

Lactoferrin inhibits dexamethasone-induced chondrocyte impairment from osteoarthritic cartilage through up-regulation of extracellular signal-regulated kinase 1/2 and suppression of FASL, FAS, and Caspase 3

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Tu, Yihui [Department of Orthopaedics, Yangpu District Central Hospital Affiliated to Tongji University School of Medicine, 450 Tengyue Road, Shanghai (China); Xue, Huaming [Department of Orthopaedics, Yangpu District Central Hospital Affiliated to Tongji University School of Medicine, 450 Tengyue Road, Shanghai (China); Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom); Francis, Wendy [Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom); Davies, Andrew P. [Department of Orthopaedics and Trauma, Moriston Hospital, Swansea (United Kingdom); Pallister, Ian; Kanamarlapudi, Venkateswarlu [Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom); Xia, Zhidao, E-mail: zhidao.xia@gmail.com [Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom)

2013-11-08

Highlights: •Dex exerts dose-dependant inhibition of HACs viability and induction of apoptosis. •Dex-induced impairment of chondrocytes was attenuated by rhLF. •ERK and FASL/FAS signaling are involved in the effects of rhLF. •OA patients with glucocorticoid-induced cartilage damage may benefit from treatment with rhLF. -- Abstract: Dexamethasone (Dex) is commonly used for osteoarthritis (OA) with excellent anti-inflammatory and analgesic effect. However, Dex also has many side effects following repeated use over prolonged periods mainly through increasing apoptosis and inhibiting proliferation. Lactoferrin (LF) exerts significantly anabolic effect on many cells and little is known about its effect on OA chondrocytes. Therefore, the aim of this study is to investigate whether LF can inhibit Dex-induced OA chondrocytes apoptosis and explore its possible molecular mechanism involved in. MTT assay was used to determine the optimal concentration of Dex and recombinant human LF (rhLF) on chondrocytes at different time and dose points. Chondrocytes were then stimulated with Dex in the absence or presence of optimal concentration of rhLF. Cell proliferation and viability were evaluated using MTT and LIVE/DEAD assay, respectively. Cell apoptosis was evaluated by multi-parameter apoptosis assay kit using both confocal microscopy and flow cytometry, respectively. The expression of extracellular signal-regulated kinase (ERK), FAS, FASL, and Caspase-3 (CASP3) at the mRNA and protein levels were examined by real-time polymerase chain reaction (PCR) and immunocytochemistry, respectively. The optimal concentration of Dex (25 μg/ml) and rhLF (200 μg/ml) were chosen for the following experiments. rhLF significantly reversed the detrimental effect of Dex on chondrocytes proliferation, viability, and apoptosis. In addition, rhLF significantly prevented Dex-induced down-regulation of ERK and up-regulation of FAS, FASL, and CASP3. These findings demonstrated that rhLF acts as

Ferulic acid suppresses activation of hepatic stellate cells through ERK1/2 and Smad signaling pathways in vitro.

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Xu, Tianjiao; Pan, Zhi; Dong, Miaoxian; Yu, Chunlei; Niu, Yingcai

2015-01-01

Hepatic stellate cells (HSCs) are the primary source of matrix components in hepatic fibrosis. Ferulic acid (FA) has antifibrotic potential in renal and cardiac disease. However, whether FA comprises inhibitive effects of HSCs activation remains to be clarified. This study aims at evaluating the hypothesis that FA inhibits extracellular matrix (ECM)-related gene expression by the interruption of the extracellular signal-regulated kinases 1 and 2 (ERK1/2) or/and Smad signaling pathways in HSC-T6. Our results indicated that FA significantly inhibited both viability and activation of HSC-T6 cells in vitro. In addition, we demonstrated, for the first time, that FA dramatically inhibited the expression of α1(I) collagen (Col-I) and fibronectin at levels of transcription and translation. Moreover, FA treatment inhibited Smad transcriptional activity, as evaluated by transient transfection with a plasmid construction containing SMAD response element and the luciferase reporter gene. Furthermore, FA inhibition of HSCs activation involved in both focal adhesion kinase (FAK)-dependent ERK1/2 and Smad signaling pathways with independent manner. Blocking transforming growth factor-β by a neutralizing antibody caused a marked reduction in both ERK1/2 and Smad signaling. These results support FA as an effective therapeutic agent for the prevention and treatment of hepatic fibrosis. Copyright © 2014 Elsevier Inc. All rights reserved.

Phosphorylation of the Grb2- and phosphatidylinositol 3-kinase p85-binding p36/38 by Syk in Lck-negative T cells.

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von Willebrand, M; Williams, S; Tailor, P; Mustelin, T

1998-06-01

Activation of the mitogen-activated protein kinase (MAPK) pathway by the T-cell antigen receptor (TCR) in T cells involves a positive role for phosphatidylinositol 3-kinase (PI3K) activity. We recently reported that over-expression of the Syk protein tyrosine kinase in the Lck-negative JCaM1 cells enabled the TCR to induce a normal activation of the Erk2 MAPK and enhanced transcription of a reporter gene driven by the nuclear factor of activated T cells and AP-1. Because this system allows us to analyse the targets for Syk in receptor-mediated signalling, we examined the role of PI3K in signalling events between the TCR-regulated Syk and the downstream activation of Erk2. We report that inhibition of PI3K by wortmannin or an inhibitory p85 construct, p85deltaiSH2, reduced the TCR-induced Syk-dependent activation of Erk2, as well as the appearance of phospho-Erk and phospho-Mek. At the same time, expression of Syk resulted in the activation-dependent phosphorylation of three proteins that bound to the src homology 2 (SH2) domains of PI3K p85. The strongest of these bands had an apparent molecular mass of 36-38 kDa on SDS gels, and it was quantitatively removed from the lysates by adsorption to a fusion protein containing the SH2 domain of Grb2. The appearance of this band was Syk dependent, and it was seen only upon triggering of the TCR complex. Thus, p36/38 was phosphorylated by Syk or a Syk-regulated kinase, and this protein may provide a link to the recruitment and activation of PI3K, as well as to the Ras-MAPK pathway, in TCR-triggered T cells.

A novel signaling pathway associated with Lyn, PI 3-kinase and Akt supports the proliferation of myeloma cells

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Iqbal, Mohd S. [Department of Bio-Signal Analysis, Applied Medical Engineering Science, Graduate School of Medicine, Yamaguchi University, Ube, Yamaguchi 755-8505 (Japan); Enteric and Food Microbiology Laboratory, Laboratory Sciences Division, International Center for Diarrhoeal Disease Research, Bangladesh, P.O. Box 128, Dhaka 1000 (Bangladesh); Tsuyama, Naohiro [Department of Analytical Molecular Medicine and Devices, Division of Frontier Medical Science, Graduate School of Medical Sciences, Hiroshima University, Hiroshima, Hiroshima 734-8553 (Japan); Obata, Masanori [Department of Bio-Signal Analysis, Applied Medical Engineering Science, Graduate School of Medicine, Yamaguchi University, Ube, Yamaguchi 755-8505 (Japan); Ishikawa, Hideaki, E-mail: hishika@yamaguchi-u.ac.jp [Department of Bio-Signal Analysis, Applied Medical Engineering Science, Graduate School of Medicine, Yamaguchi University, Ube, Yamaguchi 755-8505 (Japan)

2010-02-12

Interleukin-6 (IL-6) is a growth factor for human myeloma cells. We have recently found that in myeloma cells the activation of both signal transducer and activator of transcription (STAT) 3 and extracellular signal-regulated kinase (ERK) 1/2 is not sufficient for the IL-6-induced proliferation, which further requires the activation of the src family kinases, such as Lyn. Here we showed that the Lyn-overexpressed myeloma cell lines had the higher proliferative rate with IL-6 and the enhanced activation of the phosphatidylinositol (PI) 3-kinase and Akt. The IL-6-induced phosphorylation of STAT3 and ERK1/2 was not up-regulated in the Lyn-overexpressed cells, indicating that the Lyn-PI 3-kinase-Akt pathway is independent of these pathways. The PI 3-kinase was co-precipitated with Lyn in the Lyn-overexpressed cells of which proliferation with IL-6 was abrogated by the specific inhibitors for PI 3-kinase or Akt, suggesting that the activation of the PI 3-kinase-Akt pathway associated with Lyn is indeed related to the concomitant augmentation of myeloma cell growth. Furthermore, the decreased expression of p53 and p21{sup Cip1} proteins was observed in the Lyn-overexpressed cells, implicating a possible downstream target of Akt. This study identifies a novel IL-6-mediated signaling pathway that certainly plays a role in the proliferation of myeloma cells and this novel mechanism of MM tumor cell growth associated with Lyn would eventually contribute to the development of MM treatment.

Differential induction of c-Fos and phosphorylated ERK by a noxious stimulus after peripheral nerve injury.

Science.gov (United States)

Tabata, Mitsuyasu; Terayama, Ryuji; Maruhama, Kotaro; Iida, Seiji; Sugimoto, Tomosada

2018-03-01

In this study, we compared induction of c-Fos and phosphorylated extracellular signal-regulated kinase (p-ERK) in the spinal dorsal horn after peripheral nerve injury. We examined the spinal dorsal horn for noxious heat-induced c-Fos and p-ERK protein-like immunoreactive (c-Fos- and p-ERK-IR) neuron profiles after tibial nerve injury. The effect of administration of a MEK 1/2 inhibitor (PD98059) on noxious heat-induced c-Fos expression was also examined after tibial nerve injury. A large number of c-Fos- and p-ERK-IR neuron profiles were induced by noxious heat stimulation to the hindpaw in sham-operated animals. A marked reduction in the number of c-Fos- and p-ERK-IR neuron profiles was observed in the medial 1/3 (tibial territory) of the dorsal horn at 3 and 7 days after nerve injury. Although c-Fos-IR neuron profiles had reappeared by 14 days after injury, the number of p-ERK-IR neuron profiles remained decreased in the tibial territory of the superficial dorsal horn. Double immunofluorescence labeling for c-Fos and p-ERK induced by noxious heat stimulation to the hindpaw at different time points revealed that a large number of c-Fos-IR, but not p-ERK-IR, neuron profiles were distributed in the tibial territory after injury. Although administration of a MEK 1/2 inhibitor to the spinal cord suppressed noxious heat-induced c-Fos expression in the peroneal territory, this treatment did not alter c-Fos induction in the tibial territory after nerve injury. ERK phosphorylation may be involved in c-Fos induction in normal nociceptive responses, but not in exaggerated c-Fos induction after nerve injury.

ERK5 pathway regulates the phosphorylation of tumour suppressor hDlg during mitosis

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Inesta-Vaquera, Francisco A. [Departamento de Inmunologia y Oncologia, Centro Nacional de Biotecnologia-CSIC, Campus de Cantoblanco-UAM, 28049 Madrid (Spain); Campbell, David G.; Arthur, J. Simon C. [MRC Protein Phosphorylation Unit, Sir James Black Building, School of Life Sciences, University of Dundee, Dundee DD1 5EH (United Kingdom); Cuenda, Ana, E-mail: acuenda@cnb.csic.es [Departamento de Inmunologia y Oncologia, Centro Nacional de Biotecnologia-CSIC, Campus de Cantoblanco-UAM, 28049 Madrid (Spain)

2010-08-13

Research highlights: {yields} hDlg is phosphorylated during mitosis in multiple residues. {yields} Prospho-hDlg is excluded from the midbody during mitosis. {yields} hDlg is not phosphorylated by p38{gamma} or JNK1/2 during mitosis. {yields} ERK5 pathway mediates hDlg phosphorylation in mitosis. -- Abstract: Human disc-large (hDlg) is a scaffold protein critical for the maintenance of cell polarity and adhesion. hDlg is thought to be a tumour suppressor that regulates the cell cycle and proliferation. However, the mechanism and pathways involved in hDlg regulation during these processes is still unclear. Here we report that hDlg is phosphorylated during mitosis, and we establish the identity of at least three residues phosphorylated in hDlg; some are previously unreported. Phosphorylation affects hDlg localisation excluding it from the contact point between the two daughter cells. Our results reveal a previously unreported pathway for hDlg phosphorylation in mitosis and show that ERK5 pathway mediates hDlg cell cycle dependent phosphorylation. This is likely to have important implications in the correct timely mitotic entry and mitosis progression.

ERK5 pathway regulates the phosphorylation of tumour suppressor hDlg during mitosis

International Nuclear Information System (INIS)

Inesta-Vaquera, Francisco A.; Campbell, David G.; Arthur, J. Simon C.; Cuenda, Ana

2010-01-01

Research highlights: → hDlg is phosphorylated during mitosis in multiple residues. → Prospho-hDlg is excluded from the midbody during mitosis. → hDlg is not phosphorylated by p38γ or JNK1/2 during mitosis. → ERK5 pathway mediates hDlg phosphorylation in mitosis. -- Abstract: Human disc-large (hDlg) is a scaffold protein critical for the maintenance of cell polarity and adhesion. hDlg is thought to be a tumour suppressor that regulates the cell cycle and proliferation. However, the mechanism and pathways involved in hDlg regulation during these processes is still unclear. Here we report that hDlg is phosphorylated during mitosis, and we establish the identity of at least three residues phosphorylated in hDlg; some are previously unreported. Phosphorylation affects hDlg localisation excluding it from the contact point between the two daughter cells. Our results reveal a previously unreported pathway for hDlg phosphorylation in mitosis and show that ERK5 pathway mediates hDlg cell cycle dependent phosphorylation. This is likely to have important implications in the correct timely mitotic entry and mitosis progression.

Desloratadine citrate disodium injection, a potent histamine H(1) receptor antagonist, inhibits chemokine production in ovalbumin-induced allergic rhinitis guinea pig model and histamine-induced human nasal epithelial cells via inhibiting the ERK1/2 and NF-kappa B signal cascades.

Science.gov (United States)

Chen, Meiling; Xu, Shuhong; Zhou, Peipei; He, Guangwei; Jie, Qiong; Wu, Yulin

2015-11-15

Chemokines have chemotactic properties on leukocyte subsets whose modulation plays a pivotal role in allergic inflammatory processes. Our present study was designed to investigate the anti-allergic and anti-inflammatory properties of desloratadine citrate disodium injection (DLC) and elucidate the molecular mechanisms of its anti-inflammatory properties. The anti-allergic effects of DLC were evaluated based on allergic symptoms, serological marker production and histological changes of the nasal mucosa in guinea pigs model of allergic rhinitis. The anti-inflammatory properties and molecular mechanisms of DLC were explored by studying the regulation of a set of chemokines and extracellular signal-regulated kinase (ERK)1/2 and nuclear factor-kappa B (NF-κB) pathways, after DLC treatment in guinea pigs model of allergic rhinitis in vivo and histamine-activated human nasal epithelial cells (HNECs) in vitro. In vivo model in guinea pigs, DLC alleviated the rhinitis symptoms, inhibited inflammatory cells infiltration in nasal lavage fluid (NLF) and histamine, monocyte chemotactic protein (MCP)-1, regulated on activation normal T cell expressed, and presumably secreted (RANTEs) and interleukin (IL)-8 release in sera and P-ERK1/2 and NF-κB activation in nasal mucosa. In vitro, DLC markedly inhibited histamine-induced production of MCP-1, RANTEs and IL-8 and suppressed c-Raf, mitogen-activated protein/extracellular signal-regulated kinase kinase (MEK) and ERK1/2 activation in HNECs. These results provide evidence that DLC possesses potent anti-allergic and anti-inflammatory properties. The mechanism of action underlying DLC in allergic inflammation appears to be inhibition of the phosphorylation of ERK1/2, in addition to blocking of the NF-κB pathway. Copyright © 2015 Elsevier B.V. All rights reserved.

AGC kinases, mechanisms of regulation ‎and innovative drug development.

Science.gov (United States)

Leroux, Alejandro E; Schulze, Jörg O; Biondi, Ricardo M

2018-02-01

The group of AGC kinases consists of 63 evolutionarily related serine/threonine protein kinases comprising PDK1, PKB/Akt, SGK, PKC, PRK/PKN, MSK, RSK, S6K, PKA, PKG, DMPK, MRCK, ROCK, NDR, LATS, CRIK, MAST, GRK, Sgk494, and YANK, while two other families, Aurora and PLK, are the most closely related to the group. Eight of these families are physiologically activated downstream of growth factor signalling, while other AGC kinases are downstream effectors of a wide range of signals. The different AGC kinase families share aspects of their mechanisms of inhibition and activation. In the present review, we update the knowledge of the mechanisms of regulation of different AGC kinases. The conformation of the catalytic domain of many AGC kinases is regulated allosterically through the modulation of the conformation of a regulatory site on the small lobe of the kinase domain, the PIF-pocket. The PIF-pocket acts like an ON-OFF switch in AGC kinases with different modes of regulation, i.e. PDK1, PKB/Akt, LATS and Aurora kinases. In this review, we make emphasis on how the knowledge of the molecular mechanisms of regulation can guide the discovery and development of small allosteric modulators. Molecular probes stabilizing the PIF-pocket in the active conformation are activators, while compounds stabilizing the disrupted site are allosteric inhibitors. One challenge for the rational development of allosteric modulators is the lack of complete structural information of the inhibited forms of full-length AGC kinases. On the other hand, we suggest that the available information derived from molecular biology and biochemical studies can already guide screening strategies for the identification of innovative mode of action molecular probes and the development of selective allosteric drugs for the treatment of human diseases. Copyright © 2017 Elsevier Ltd. All rights reserved.

Glucose dependence of glycogen synthase activity regulation by GSK3 and MEK/ERK inhibitors and angiotensin-(1-7) action on these pathways in cultured human myotubes.

Science.gov (United States)

Montori-Grau, Marta; Tarrats, Núria; Osorio-Conles, Oscar; Orozco, Anna; Serrano-Marco, Lucía; Vázquez-Carrera, Manuel; Gómez-Foix, Anna M

2013-05-01

Glycogen synthase (GS) is activated by glucose/glycogen depletion in skeletal muscle cells, but the contributing signaling pathways, including the chief GS regulator GSK3, have not been fully defined. The MEK/ERK pathway is known to regulate GSK3 and respond to glucose. The aim of this study was to elucidate the GSK3 and MEK/ERK pathway contribution to GS activation by glucose deprivation in cultured human myotubes. Moreover, we tested the glucose-dependence of GSK3 and MEK/ERK effects on GS and angiotensin (1-7) actions on these pathways. We show that glucose deprivation activated GS, but did not change phospho-GS (Ser640/1), GSK3β activity or activity-activating phosphorylation of ERK1/2. We then treated glucose-replete and -depleted cells with SB415286, U0126, LY294 and rapamycin to inhibit GSK3, MEK1/2, PI3K and mTOR, respectively. SB415286 activated GS and decreased the relative phospho-GS (Ser640/1) level, more in glucose-depleted than -replete cells. U0126 activated GS and reduced the phospho-GS (Ser640/1) content significantly in glucose-depleted cells, while GSK3β activity tended to increase. LY294 inactivated GS in glucose-depleted cells only, without affecting relative phospho-GS (Ser640/1) level. Rapamycin had no effect on GS activation. Angiotensin-(1-7) raised phospho-ERK1/2 but not phospho-GSK3β (Ser9) content, while it inactivated GS and increased GS phosphorylation on Ser640/1, in glucose-replete cells. In glucose-depleted cells, angiotensin-(1-7) effects on ERK1/2 and GS were reverted, while relative phospho-GSK3β (Ser9) content decreased. In conclusion, activation of GS by glucose deprivation is not due to GS Ser640/1 dephosphorylation, GSK3β or ERK1/2 regulation in cultured myotubes. However, glucose depletion enhances GS activation/Ser640/1 dephosphorylation due to both GSK3 and MEK/ERK inhibition. Angiotensin-(1-7) inactivates GS in glucose-replete cells in association with ERK1/2 activation, not with GSK3 regulation, and glucose

Fluid shear stress suppresses TNF-α-induced apoptosis in MC3T3-E1 cells: Involvement of ERK5-AKT-FoxO3a-Bim/FasL signaling pathways

Energy Technology Data Exchange (ETDEWEB)

Bin, Geng; Bo, Zhang; Jing, Wang; Jin, Jiang; Xiaoyi, Tan; Cong, Chen; Liping, An; Jinglin, Ma; Cuifang, Wang; Yonggang, Chen [The Second Hospital of Lanzhou University, #82 Cuiyingmen, Lanzhou, 730000 Gansu (China); Orthopaedics Key Laboratory of Gansu Province, Lanzhou, 730000 Gansu (China); Yayi, Xia, E-mail: xiayayildey@163.com [The Second Hospital of Lanzhou University, #82 Cuiyingmen, Lanzhou, 730000 Gansu (China); Orthopaedics Key Laboratory of Gansu Province, Lanzhou, 730000 Gansu (China)

2016-05-01

TNF-α is known to induce osteoblasts apoptosis, whereas mechanical stimulation has been shown to enhance osteoblast survival. In the present study, we found that mechanical stimulation in the form of fluid shear stress (FSS) suppresses TNF-α induced apoptosis in MC3T3-E1 cells. Extracellular signal-regulated kinase 5 (ERK5) is a member of the mitogen-activated protein kinase (MAPK) family that has been implicated in cell survival. We also demonstrated that FSS imposed by flow chamber in vitro leads to a markedly activation of ERK5, which was shown to be protective against TNF-α-induced apoptosis, whereas the transfection of siRNA against ERK5 (ERK5-siRNA) reversed the FSS-medicated anti-apoptotic effects. An initial FSS-mediated activation of ERK5 that phosphorylates AKT to increase its activity, and a following forkhead box O 3a (FoxO3a) was phosphorylated by activated AKT. Phosphorylated FoxO3a is sequestered in the cytoplasm, and prevents it from translocating to nucleus where it can increase the expression of FasL and Bim. The inhibition of AKT-FoxO3a signalings by a PI3K (PI3-kinase)/AKT inhibitor (LY294002) or the transfection of ERK5-siRNA led to the nuclear translocation of non-phosphorylated FoxO3a, and increased the protein expression of FasL and Bim. In addition, the activation of caspase-3 by TNF-α was significantly inhibited by aforementioned FSS-medicated mechanisms. In brief, the activation of ERK5-AKT-FoxO3a signaling pathways by FSS resulted in a decreased expression of FasL and Bim and an inhibition of caspase-3 activation, which exerts a protective effect that prevents osteoblasts from apoptosis. - Highlights: • Fluid shear stress inhibits osteoblast apoptosis induced by TNF-α. • Inhibition of ERK5 activity by transfection of ERK5 siRNA blocks FSS-mediated anti-apoptotic effect in osteoblast. • Activated ERK5-AKT-FoxO3a-Bim/FasL signaling pathways by FSS is required to protect osteoblast from apoptosis.

Activation of PI3K/AKT and ERK MAPK signal pathways is required for the induction of lytic cycle replication of Kaposi's Sarcoma-associated herpesvirus by herpes simplex virus type 1

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Lv Zhigang

2011-10-01

Full Text Available Abstract Background Kaposi's sarcoma-associated herpesvirus (KSHV is causally linked to several acquired immunodeficiency syndrome-related malignancies, including Kaposi's sarcoma (KS, primary effusion lymphoma (PEL and a subset of multicentric Castleman's disease. Regulation of viral lytic replication is critical to the initiation and progression of KS. Recently, we reported that herpes simplex virus type 1 (HSV-1 was an important cofactor that activated lytic cycle replication of KSHV. Here, we further investigated the possible signal pathways involved in HSV-1-induced reactivation of KSHV. Results By transfecting a series of dominant negative mutants and protein expressing constructs and using pharmacologic inhibitors, we found that either Janus kinase 1 (JAK1/signal transducer and activator of transcription 3 (STAT3 or JAK1/STAT6 signaling failed to regulate HSV-1-induced KSHV replication. However, HSV-1 infection of BCBL-1 cells activated phosphatidylinositol 3-kinase (PI3K/protein kinase B (PKB, also called AKT pathway and inactivated phosphatase and tensin homologue deleted on chromosome ten (PTEN and glycogen synthase kinase-3β (GSK-3β. PTEN/PI3K/AKT/GSK-3β pathway was found to be involved in HSV-1-induced KSHV reactivation. Additionally, extracellular signal-regulated protein kinase (ERK mitogen-activated protein kinase (MAPK pathway also partially contributed to HSV-1-induced KSHV replication. Conclusions HSV-1 infection stimulated PI3K/AKT and ERK MAPK signaling pathways that in turn contributed to KSHV reactivation, which provided further insights into the molecular mechanism controlling KSHV lytic replication, particularly in the context of HSV-1 and KSHV co-infection.

The role of identified neurotransmitter systems in the response of insular cortex to unfamiliar taste: activation of ERK1-2 and formation of a memory trace.

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Berman, D E; Hazvi, S; Neduva, V; Dudai, Y

2000-09-15

In the behaving rat, the consumption of an unfamiliar taste activates the extracellular signal-regulated kinase 1-2 (ERK1-2) in the insular cortex, which contains the taste cortex. In contrast, consumption of a familiar taste has no effect. Furthermore, activation of ERK1-2, culminating in modulation of gene expression, is obligatory for the encoding of long-term, but not short-term, memory of the new taste (Berman et al., 1998). Which neurotransmitter and neuromodulatory systems are involved in the activation of ERK1-2 by the unfamiliar taste and in the long-term encoding of the new taste information? Here we show, by the use of local microinjections of pharmacological agents to the insular cortex in the behaving rat, that multiple neurotransmitters and neuromodulators are required for encoding of taste memory in cortex. However, these systems vary in the specificity of their role in memory acquisition and in their contribution to the activation of ERK1-2. NMDA receptors, metabotropic glutamate receptors, muscarinic, and beta-adrenergic and dopaminergic receptors, all contribute to the acquisition of the new taste memory but not to its retrieval. Among these, only NMDA and muscarinic receptors specifically mediate taste-dependent activation of ERK1-2, whereas the beta-adrenergic function is independent of ERK1-2, and dopaminergic receptors regulate also the basal level of ERK1-2 activation. The data are discussed in the context of postulated novelty detection circuits in the central taste system.

Vitamin E and Lycopene Reduce Coal Burning Fluorosis-induced Spermatogenic Cell Apoptosis via Oxidative Stress-mediated JNK and ERK Signaling Pathways.

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Tian, Yuan; Xiao, Yuehai; Wang, Bolin; Sun, Chao; Tang, Kaifa; Sun, Fa

2017-12-22

Although fluoride has been widely used in toothpaste, mouthwash, and drinking water to prevent dental caries, the excessive intake of fluoride can cause fluorosis which is associated with dental, skeletal, and soft tissue fluorosis. Recent evidences have drawn the attention to its adverse effects on male reproductive system that include spermatogenesis defect, sperm count loss, and sperm maturation impairment. Fluoride induces oxidative stress through the activation of mitogen activated protein kinase (MAPK) cascade which can lead to cell apoptosis. Vitamin E (VE) and lycopene are two common anti-oxidants, being protective to reactive oxygen species (ROS)-induced toxic effects. However, whether and how these two anti-oxidants prevent fluoride-induced spermatogenic cell apoptosis are largely unknown. In the present study, a male rat model for coal burning fluorosis was established and the histological lesions and spermatogenic cell apoptosis in rat testes were observed. The decreased expression of clusterin, a heterodimeric glycoprotein reported to regulate spermatogenic cell apoptosis, is detected in fluoride-treated rat testes. Interestingly, the co-administration with VE or lycopene reduced fluorosis-mediated testicular toxicity and rescued clusterin expression. Further, fluoride caused the enhanced Jun N-terminal kinase (JNK) and extracellular signal-regulated protein kinase (ERK) phosphorylation, which was reduced by VE or lycopene. Thus, VE and lycopene prevent coal burning fluorosis-induced spermatogenic cell apoptosis through the suppression of oxidative stress-mediated JNK and ERK signaling pathway, which could be an alternative therapeutic strategy for the treatment of fluorosis. ©2017 The Author(s).

Valsartan ameliorates ageing-induced aorta degeneration via angiotensin II type 1 receptor-mediated ERK activity

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Shan, HaiYan; Zhang, Siyang; Li, Xuelian; yu, Kai; Zhao, Xin; Chen, Xinyue; Jin, Bo; Bai, XiaoJuan

2014-01-01

Angiotensin II (Ang II) plays important roles in ageing-related disorders through its type 1 receptor (AT1R). However, the role and underlying mechanisms of AT1R in ageing-related vascular degeneration are not well understood. In this study, 40 ageing rats were randomly divided into two groups: ageing group which received no treatment (ageing control), and valsartan group which took valsartan (selective AT1R blocker) daily for 6 months. 20 young rats were used as adult control. The aorta structure were analysed by histological staining and electron microscopy. Bcl-2/Bax expression in aorta was analysed by immunohistochemical staining, RT-PCR and Western blotting. The expressions of AT1R, AT2R and mitogen-activated protein kinases (MAPKs) were detected. Significant structural degeneration of aorta in the ageing rats was observed, and the degeneration was remarkably ameliorated by long-term administration of valsartan. With ageing, the expression of AT1R was elevated, the ratio of Bcl-2/Bax was decreased and meanwhile, an important subgroup of MAPKs, extracellular signal-regulated kinase (ERK) activity was elevated. However, these changes in ageing rats could be reversed to some extent by valsartan. In vitro experiments observed consistent results as in vivo study. Furthermore, ERK inhibitor could also acquire partial effects as valsartan without affecting AT1R expression. The results indicated that AT1R involved in the ageing-related degeneration of aorta and AT1R-mediated ERK activity was an important mechanism underlying the process. PMID:24548645

ERα and ERK1/2 MAP kinase expression in microdissected stromal and epithelial endometrial cells

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Said Abu Alkhair Mohamed

2014-03-01

Total and phosphorylated levels for ERK1/2 and ERα were measured by quantitation of signals from Western blots using specific antibodies against the active and total forms of ERK1/2 and against ERα. When the level of the proteins was quantitated and normalized to β actin from microdissected stroma and epithelium, no significant difference was detected in the levels of these proteins between the two tissue compartments. There was a trend toward higher expression in the stroma vs. epithelium, respectively (active ERK1/2 0.45 ± 0.17 vs. 0.2 ± 0.65; total ERK1/2 0.54 ± 0.35 vs. 0.28 ± 0.23; ERα 0.82 ± 0.28 vs. 0.54 ± 0.18; n = 6. These data demonstrate that there are comparable levels of ERα (P = 0.41, total ERK1/2 (P = 0.18 and active ERK1/2 (P = 0.13 in the stroma and epithelium of proliferative phase endometrium with a trend toward higher expression of these proteins in the stromal compartment.

Diacylglycerol kinase regulation of protein kinase D during oxidative stress-induced intestinal cell injury

International Nuclear Information System (INIS)

Song Jun; Li Jing; Mourot, Joshua M.; Mark Evers, B.; Chung, Dai H.

2008-01-01

We recently demonstrated that protein kinase D (PKD) exerts a protective function during oxidative stress-induced intestinal epithelial cell injury; however, the exact role of DAG kinase (DGK)ζ, an isoform expressed in intestine, during this process is unknown. We sought to determine the role of DGK during oxidative stress-induced intestinal cell injury and whether DGK acts as an upstream regulator of PKD. Inhibition of DGK with R59022 compound or DGKζ siRNA transfection decreased H 2 O 2 -induced RIE-1 cell apoptosis as measured by DNA fragmentation and increased PKD phosphorylation. Overexpression of kinase-dead DGKζ also significantly increased PKD phosphorylation. Additionally, endogenous nuclear DGKζ rapidly translocated to the cytoplasm following H 2 O 2 treatment. Our findings demonstrate that DGK is involved in the regulation of oxidative stress-induced intestinal cell injury. PKD activation is induced by DGKζ, suggesting DGK is an upstream regulator of oxidative stress-induced activation of the PKD signaling pathway in intestinal epithelial cells

Simulated physiological stretch increases expression of extracellular matrix proteins in human bladder smooth muscle cells via integrin α4/αv-FAK-ERK1/2 signaling pathway.

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Chen, Shulian; Peng, Chuandu; Wei, Xin; Luo, Deyi; Lin, Yifei; Yang, Tongxin; Jin, Xi; Gong, Lina; Li, Hong; Wang, Kunjie

2017-08-01

To investigate the effect of simulated physiological stretch on the expression of extracellular matrix (ECM) proteins and the role of integrin α4/αv, focal adhesion kinase (FAK), extracellular regulated protein kinases 1/2 (ERK1/2) in the stretch-induced ECM protein expression of human bladder smooth muscle cells (HBSMCs). HBSMCs were seeded onto silicone membrane and subjected to simulated physiological stretch at the range of 5, 10, and 15% elongation. Expression of primary ECM proteins in HBSMCs was analyzed by real-time polymerase chain reaction and Western blot. Specificity of the FAK and ERK1/2 was determined by Western blot with FAK inhibitor and ERK1/2 inhibitor (PD98059). Specificity of integrin α4 and integrin αv was determined with small interfering ribonucleic acid (siRNA) transfection. The expression of collagen I (Col1), collagen III (Col3), and fibronectin (Fn) was increased significantly under the simulated physiological stretch of 10 and 15%. Integrin α4 and αv, FAK, ERK1/2 were activated by 10% simulated physiological stretch compared with the static condition. Pretreatment of ERK1/2 inhibitor, FAK inhibitor, integrin α4 siRNA, or integrin αv siRNA reduced the stretch-induced expression of ECM proteins. And FAK inhibitor decreased the stretch-induced ERK1/2 activity and ECM protein expression. Integrin α4 siRNA or integrin αv siRNA inhibited the stretch-induced activity of FAK. Simulated physiological stretch increases the expression of ECM proteins in HBSMCs, and integrin α4/αv-FAK-ERK1/2 signaling pathway partly modulates the mechano-transducing process.

Methylselenol, a selenium metabolite, induces cell cycle arrest in G1 phase and apoptosis via the extracellular-regulated kinase 1/2 pathway and other cancer signaling genes.

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Zeng, Huawei; Wu, Min; Botnen, James H

2009-09-01

Methylselenol has been hypothesized to be a critical selenium (Se) metabolite for anticancer activity in vivo, and our previous study demonstrated that submicromolar methylselenol generated by incubating methionase with seleno-l-methionine inhibits the migration and invasive potential of HT1080 tumor cells. However, little is known about the association between cancer signal pathways and methylselenol's inhibition of tumor cell invasion. In this study, we demonstrated that methylselenol exposure inhibited cell growth and we used a cancer signal pathway-specific array containing 15 different signal transduction pathways involved in oncogenesis to study the effect of methylselenol on cellular signaling. Using real-time RT-PCR, we confirmed that cellular mRNA levels of cyclin-dependent kinase inhibitor 1C (CDKN1C), heme oxygenase 1, platelet/endothelial cell adhesion molecule, and PPARgamma genes were upregulated to 2.8- to 5.7-fold of the control. BCL2-related protein A1, hedgehog interacting protein, and p53 target zinc finger protein genes were downregulated to 26-52% of the control, because of methylselenol exposure. These genes are directly related to the regulation of cell cycle and apoptosis. Methylselenol increased apoptotic cells up to 3.4-fold of the control and inhibited the extracellular-regulated kinase 1/2 (ERK1/2) signaling and cellular myelocytomatosis oncogene (c-Myc) expression. Taken together, our studies identify 7 novel methylselenol responsive genes and demonstrate that methylselenol inhibits ERK1/2 pathway activation and c-Myc expression. The regulation of these genes is likely to play a key role in G1 cell cycle arrest and apoptosis, which may contribute to the inhibition of tumor cell invasion.

[Electroacupuncture Intervention Enhances Splenic Natural Killer Cell Activity via Inhibiting Phosphorylation of ERK 5 in the Hypothalamus of Surgically Traumatized Rats].

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Chen, Yan; Li, Jing; Zhu, Ke-ying; Xiao, Sheng; Wang, Yan-qing; Wu, Gen-cheng; Wang, Jun

2015-06-01

To observe the effect of electroacupuncture (EA) on cytotoxic activity of splenic natural killer (NK) cells after surgical trauma via extracellular signal-regulated kinase (ERK) 5 pathway in the rats' hypothalamus, so as to explore its mechanism underlying improving immune disorders after surgery. Sprague-Dawley rats were randomly divided into the following 6 groups: control, trauma model, EA, sham EA, 4 nmol-BIX 02188 (an inhibitor for ERK 5 catalytic activity) and 20 nmol-BIX 02188 (n = 6 rats per group). The surgical trauma model was established by making a longitudinal incision (6 cm in length) along the median line of the back to expose the spinal column and another longitudinal incision along the abdominal median line. EA (2 Hz/15 Hz, 1 - 2 mA) was applied to bilateral "Zusanli" (ST 36) for 30 min immediately after surgery. For rats of the BIX groups, intra-lateral ventricular microinjection of BIX 02188 (10 µL, 4 nmol or 20 nmol, or saline for control rats) was conducted 30 min before the surgery. The expression level and protein of phosphorylated ERK 5 (p-ERK 5) and corticotropin-releasing factor (CRF) protein were measured by immunohistochemistry and Western blot, respectively. The cytotoxicity of splenic NK cells and the expression of splenic Perforin and Granzyme-B genes were measured by lactate dehydrogenase (LDH) release assay and real-time PCR, respectively. In comparison with the control group, hypothalamic p-ERK 5 immunoactivity, p-ERK 5 protein and CRF protein expression levels were significantly up-regulated in the model group (Psplenic NK cell cytotoxicity and Perforin mRNA and Granzyme-B mRNA expression levels were notably down-regulated in the model group (P 0. 05) except the increased p-ERK 5 protein in the 4 nmol-BIX 02188 group. In addition, the down-regulated NK cell activity, Perforin mRNA and Granzyme-B mRNA expression levels were significantly reversed in the EA and 20 nmol-BIX 02188 groups (Psplenic NK cytotoxicity and Perforin and

Transforming Growth Factor β1-induced Apoptosis in Podocytes via the Extracellular Signal-regulated Kinase-Mammalian Target of Rapamycin Complex 1-NADPH Oxidase 4 Axis.

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Das, Ranjan; Xu, Shanhua; Nguyen, Tuyet Thi; Quan, Xianglan; Choi, Seong-Kyung; Kim, Soo-Jin; Lee, Eun Young; Cha, Seung-Kuy; Park, Kyu-Sang

2015-12-25

TGF-β is a pleiotropic cytokine that accumulates during kidney injuries, resulting in various renal diseases. We have reported previously that TGF-β1 induces the selective up-regulation of mitochondrial Nox4, playing critical roles in podocyte apoptosis. Here we investigated the regulatory mechanism of Nox4 up-regulation by mTORC1 activation on TGF-β1-induced apoptosis in immortalized podocytes. TGF-β1 treatment markedly increased the phosphorylation of mammalian target of rapamycin (mTOR) and its downstream targets p70S6K and 4EBP1. Blocking TGF-β receptor I with SB431542 completely blunted the phosphorylation of mTOR, p70S6K, and 4EBP1. Transient adenoviral overexpression of mTOR-WT and constitutively active mTORΔ augmented TGF-β1-treated Nox4 expression, reactive oxygen species (ROS) generation, and apoptosis, whereas mTOR kinase-dead suppressed the above changes. In addition, knockdown of mTOR mimicked the effect of mTOR-KD. Inhibition of mTORC1 by low-dose rapamycin or knockdown of p70S6K protected podocytes through attenuation of Nox4 expression and subsequent oxidative stress-induced apoptosis by TGF-β1. Pharmacological inhibition of the MEK-ERK cascade, but not the PI3K-Akt-TSC2 pathway, abolished TGF-β1-induced mTOR activation. Inhibition of either ERK1/2 or mTORC1 did not reduce the TGF-β1-stimulated increase in Nox4 mRNA level but significantly inhibited total Nox4 expression, ROS generation, and apoptosis induced by TGF-β1. Moreover, double knockdown of Smad2 and 3 or only Smad4 completely suppressed TGF-β1-induced ERK1/2-mTORactivation. Our data suggest that TGF-β1 increases translation of Nox4 through the Smad-ERK1/2-mTORC1 axis, which is independent of transcriptional regulation. Activation of this pathway plays a crucial role in ROS generation and mitochondrial dysfunction, leading to podocyte apoptosis. Therefore, inhibition of the ERK1/2-mTORC1 pathway could be a potential therapeutic and preventive target in proteinuric and chronic

Differential roles of MAPK-Erk1/2 and MAPK-p38 in insulin or insulin-like growth factor-I (IGF-I) signaling pathways for progesterone production in human ovarian cells.

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Seto-Young, D; Avtanski, D; Varadinova, M; Park, A; Suwandhi, P; Leiser, A; Parikh, G; Poretsky, L

2011-06-01

Insulin and insulin like-growth factor-I (IGF-I) participate in the regulation of ovarian steroidogenesis. In insulin resistant states ovaries remain sensitive to insulin because insulin can activate alternative signaling pathways, such as phosphatidylinositol-3-kinase (PI-3 kinase) and mitogen-activated protein-kinase (MAPK) pathways, as well as insulin receptors and type 1 IGF receptors. We investigated the roles of MAPK-Erk1/2 and MAPK-p38 in insulin and IGF-I signaling pathways for progesterone production in human ovarian cells. Human ovarian cells were cultured in tissue culture medium in the presence of varying concentrations of insulin or IGF-I, with or without PD98059, a specific MAPK-Erk1/2 inhibitor, with or without SB203580, a specific MAPK-p38 inhibitor or with or without a specific PI-3-kinase inhibitor LY294002. Progesterone concentrations were measured using radioimmunoassay. PD98059 alone stimulated progesterone production in a dose-dependent manner by up to 65% (pprogesterone production by 13-18% (pprogesterone production by 17-20% (pprogesterone production by 20-30% (pprogesterone production by 40-60% (pprogesterone synthesis while SB203580 abolished insulin-induced progesterone production. Either PD98059 or SB203580 abolished IGF-I-induced progesterone production. Both MAPK-Erk1/2 and MAPK-p38 participate in IGF-I-induced signaling pathways for progesterone production, while insulin-induced progesterone production requires MAPK-p38, but not MAPK-Erk1/2. These studies provide further evidence for divergence of insulin and IGF-I signaling pathways for human ovarian cell steroidogenesis. © Georg Thieme Verlag KG Stuttgart · New York.

Induction of viral, 7-methyl-guanosine cap-independent translation and oncolysis by mitogen-activated protein kinase-interacting kinase-mediated effects on the serine/arginine-rich protein kinase.

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Brown, Michael C; Bryant, Jeffrey D; Dobrikova, Elena Y; Shveygert, Mayya; Bradrick, Shelton S; Chandramohan, Vidyalakshmi; Bigner, Darell D; Gromeier, Matthias

2014-11-01

Protein synthesis, the most energy-consuming process in cells, responds to changing physiologic priorities, e.g., upon mitogen- or stress-induced adaptations signaled through the mitogen-activated protein kinases (MAPKs). The prevailing status of protein synthesis machinery is a viral pathogenesis factor, particularly for plus-strand RNA viruses, where immediate translation of incoming viral RNAs shapes host-virus interactions. In this study, we unraveled signaling pathways centered on the ERK1/2 and p38α MAPK-interacting kinases MNK1/2 and their role in controlling 7-methyl-guanosine (m(7)G) "cap"-independent translation at enterovirus type 1 internal ribosomal entry sites (IRESs). Activation of Raf-MEK-ERK1/2 signals induced viral IRES-mediated translation in a manner dependent on MNK1/2. This effect was not due to MNK's known functions as eukaryotic initiation factor (eIF) 4G binding partner or eIF4E(S209) kinase. Rather, MNK catalytic activity enabled viral IRES-mediated translation/host cell cytotoxicity through negative regulation of the Ser/Arg (SR)-rich protein kinase (SRPK). Our investigations suggest that SRPK activity is a major determinant of type 1 IRES competency, host cell cytotoxicity, and viral proliferation in infected cells. We are targeting unfettered enterovirus IRES activity in cancer with PVSRIPO, the type 1 live-attenuated poliovirus (PV) (Sabin) vaccine containing a human rhinovirus type 2 (HRV2) IRES. A phase I clinical trial of PVSRIPO with intratumoral inoculation in patients with recurrent glioblastoma (GBM) is showing early promise. Viral translation proficiency in infected GBM cells is a core requirement for the antineoplastic efficacy of PVSRIPO. Therefore, it is critically important to understand the mechanisms controlling viral cap-independent translation in infected host cells. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Cryptotanshinone Regulates Androgen Synthesis through the ERK/c-Fos/CYP17 Pathway in Porcine Granulosa Cells

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Danfeng Ye

2017-01-01

Full Text Available The aim of the study is to investigate the molecular mechanism behind androgen reduction in porcine granulosa cells (pGCs with Salvia miltiorrhiza Bunge extract cryptotanshinone. PGCs were isolated from porcine ovaries and identified. Androgen excess model of the pGCs was induced with the MAPK inhibitor PD98059 and then treated with cryptotanshinone. The testosterone level was measured by radioimmunoassay in the culture media. The protein levels of P-ERK1/2, c-Fos, and CYP17 in the cells were measured by western blot. Cryptotanshinone decreased the concentration of testosterone and the protein level of CYP17 and increased the protein levels of P-ERK1/2 and c-Fos in the androgen excess mode. After the c-Fos gene was silenced by infection with c-Fos shRNA lentivirus, we measured the mRNA expression by quantitative RT-PCR and protein level by western blot of P-ERK1/2, c-Fos, and CYP17. This showed that the mRNA expression and protein level of P-ERK1/2 and c-Fos were significantly reduced in the shRNA–c-Fos group compared to the scrambled group, while those of CYP17 were significantly increased. So we concluded that cryptotanshinone can significantly reduce the androgen excess induced by PD98059 in pGCs. The possible molecular mechanism for this activity is regulating the ERK/c-Fos/CYP17 pathway.

RKIP phosphorylation–dependent ERK1 activation stimulates adipogenic lipid accumulation in 3T3-L1 preadipocytes overexpressing LC3

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Hahm, Jong Ryeal [Department of Internal Medicine, Gyeongsang National University School of Medicine, JinJu, 527-27 (Korea, Republic of); Institute of Health Sciences, Gyeongsang National University School of Medicine, JinJu, 527-27 (Korea, Republic of); Ahmed, Mahmoud [Department of Biochemistry and Convergence Medical Science, Gyeongsang National University School of Medicine, JinJu, 527-27 (Korea, Republic of); Institute of Health Sciences, Gyeongsang National University School of Medicine, JinJu, 527-27 (Korea, Republic of); Kim, Deok Ryong, E-mail: drkim@gnu.ac.kr [Department of Biochemistry and Convergence Medical Science, Gyeongsang National University School of Medicine, JinJu, 527-27 (Korea, Republic of); Institute of Health Sciences, Gyeongsang National University School of Medicine, JinJu, 527-27 (Korea, Republic of)

2016-09-09

3T3-L1 preadipocytes undergo adipogenesis in response to treatment with dexamethaxone, 1-methyl-3-isobutylxanthine, and insulin (DMI) through activation of several adipogenic transcription factors. Many autophagy-related proteins are also highly activated in the earlier stages of adipogenesis, and the LC3 conjugation system is required for formation of lipid droplets. Here, we investigated the effect of overexpression of green fluorescent protein (GFP)-LC3 fusion protein on adipogenesis. Overexpression of GFP-LC3 in 3T3-L1 preadipocytes using poly-L-lysine-assisted adenoviral GFP-LC3 transduction was sufficient to produce intracellular lipid droplets. Indeed, GFP-LC3 overexpression stimulated expression of some adipogenic transcription factors (e.g., C/EBPα or β, PPARγ, SREBP2). In particular, SREBP2 was highly activated in preadipocytes transfected with adenoviral GFP-LC3. Also, phosphorylation of Raf kinase inhibitory protein (RKIP) at serine 153, consequently stimulating extracellular-signal regulated kinase (ERK)1 activity, was significantly increased during adipogenesis induced by either poly-L-lysine-assisted adenoviral GFP-LC3 transduction or culture in the presence of dexamethasone, 1-methyl-3-isobutylxanthine, and insulin. Furthermore, RKIP knockdown promoted ERK1 and PPARγ activation, and significantly increased the intracellular accumulation of triacylglycerides in DMI-induced adipogenesis. In conclusion, GFP-LC3 overexpression in 3T3-L1 preadipocytes stimulates adipocyte differentiation via direct modulation of RKIP-dependent ERK1 activity. - Highlights: • Overexpression of GFP-LC3 in 3T3-L1 cells produces intracellular lipid droplets. • SREBP2 is highly activated in preadipocytes transfected with adenoviral GFP-LC3. • RKIP phosphorylation at serine 153 is significantly increased during adipogenesis. • RKIP knockdown promotes ERK1 and PPARγ activation during adipogenesis. • RKIP-dependent ERK1 activation increases triacylglycerides in

Regulation of PPAR{gamma} function by TNF-{alpha}

Energy Technology Data Exchange (ETDEWEB)

Ye Jianping [Pennington Biomedical Research Center, Louisiana State University System, 6400 Perkins Road, Baton Rouge, LA 70808 (United States)], E-mail: yej@pbrc.edu

2008-09-26

The nuclear receptor PPAR{gamma} is a lipid sensor that regulates lipid metabolism through gene transcription. Inhibition of PPAR{gamma} activity by TNF-{alpha} is involved in pathogenesis of insulin resistance, atherosclerosis, inflammation, and cancer cachexia. PPAR{gamma} activity is regulated by TNF-{alpha} at pre-translational and post-translational levels. Activation of serine kinases including IKK, ERK, JNK, and p38 may be involved in the TNF-regulation of PPAR{gamma}. Of the four kinases, IKK is a dominant signaling molecule in the TNF-regulation of PPAR{gamma}. IKK acts through at least two mechanisms: inhibition of PPAR{gamma} expression and activation of PPAR{gamma} corepressor. In this review article, literature is reviewed with a focus on the mechanisms of PPAR{gamma} inhibition by TNF-{alpha}.

Effects of Forced Swimming Stress on ERK and Histone H3 Phosphorylation in Limbic Areas of Roman High- and Low-Avoidance Rats.

Science.gov (United States)

Morello, Noemi; Plicato, Ornella; Piludu, Maria Antonietta; Poddighe, Laura; Serra, Maria Pina; Quartu, Marina; Corda, Maria Giuseppa; Giorgi, Osvaldo; Giustetto, Maurizio

2017-01-01

Stressful events evoke molecular adaptations of neural circuits through chromatin remodeling and regulation of gene expression. However, the identity of the molecular pathways activated by stress in experimental models of depression is not fully understood. We investigated the effect of acute forced swimming (FS) on the phosphorylation of the extracellular signal-regulated kinase (ERK)1/2 (pERK) and histone H3 (pH3) in limbic brain areas of genetic models of vulnerability (RLA, Roman low-avoidance rats) and resistance (RHA, Roman high-avoidance rats) to stress-induced depression-like behavior. We demonstrate that FS markedly increased the density of pERK-positive neurons in the infralimbic (ILCx) and the prelimbic area (PrLCx) of the prefrontal cortex (PFCx), the nucleus accumbens, and the dorsal blade of the hippocampal dentate gyrus to the same extent in RLA and RHA rats. In addition, FS induced a significant increase in the intensity of pERK immunoreactivity (IR) in neurons of the PFCx in both rat lines. However, RHA rats showed stronger pERK-IR than RLA rats in the ILCx both under basal and stressed conditions. Moreover, the density of pH3-positive neurons was equally increased by FS in the PFCx of both rat lines. Interestingly, pH3-IR was higher in RHA than RLA rats in PrLCx and ILCx, either under basal conditions or upon FS. Finally, colocalization analysis showed that in the PFCx of both rat lines, almost all pERK-positive cells express pH3, whereas only 50% of the pH3-positive neurons is also pERK-positive. Moreover, FS increased the percentage of neurons that express exclusively pH3, but reduced the percentage of cells expressing exclusively pERK. These results suggest that (i) the distinctive patterns of FS-induced ERK and H3 phosphorylation in the PFCx of RHA and RLA rats may represent molecular signatures of the behavioural traits that distinguish the two lines and (ii) FS-induced H3 phosphorylation is, at least in part, ERK-independent.

Triiodothyronine promotes the proliferation of epicardial progenitor cells through the MAPK/ERK pathway.

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Deng, Song-Bai; Jing, Xiao-Dong; Wei, Xiao-Ming; Du, Jian-Lin; Liu, Ya-Jie; Qin, Qin; She, Qiang

2017-04-29

Thyroid hormone has important functions in the development and physiological function of the heart. The aim of this study was to determine whether 3,5,3'-Triiodothyronine (T3) can promote the proliferation of epicardial progenitor cells (EPCs) and to investigate the potential underlying mechanism. Our results showed that T3 significantly promoted the proliferation of EPCs in a concentration- and time-dependent manner. The thyroid hormone nuclear receptor inhibitor bisphenol A (100 μmol/L) did not affect T3's ability to induce proliferation. Further studies showed that the mRNA expression levels of mitogen-activated protein kinase 1 (MAPK1), MAPK3, and Ki67 in EPCs in the T3 group (10 nmol/L) increased 2.9-, 3-, and 4.1-fold, respectively, compared with those in the control group (P < 0.05). In addition, the mRNA expression of the cell cycle protein cyclin D1 in the T3 group increased approximately 2-fold compared with the control group (P < 0.05), and there were more EPCs in the S phase of the cell cycle (20.6% vs. 12.0%, P < 0.05). The mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling pathway inhibitor U0126 (10 μmol/L) significantly inhibited the ability of T3 to promote the proliferation of EPCs and to alter cell cycle progression. This study suggested that T3 significantly promotes the proliferation of EPCs, and this effect may be achieved through activation of the MAPK/ERK signaling pathway. Copyright © 2017 Elsevier Inc. All rights reserved.

NANOG Is Multiply Phosphorylated and Directly Modified by ERK2 and CDK1 In Vitro

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Justin Brumbaugh

2014-01-01

Full Text Available NANOG is a divergent homeobox protein and a core component of the transcriptional circuitry that sustains pluripotency and self-renewal. Although NANOG has been extensively studied on the transcriptional level, little is known regarding its posttranslational regulation, likely due to its low abundance and challenging physical properties. Here, we identify eleven phosphorylation sites on endogenous human NANOG, nine of which mapped to single amino acids. To screen for the signaling molecules that impart these modifications, we developed the multiplexed assay for kinase specificity (MAKS. MAKS simultaneously tests activity for up to ten kinases while directly identifying the substrate and exact site of phosphorylation. Using MAKS, we discovered site-specific phosphorylation by ERK2 and CDK1/CyclinA2, providing a putative link between key signaling pathways and NANOG.

Focal adhesion kinase, a downstream mediator of Raf-1 signaling, suppresses cellular adhesion, migration, and neuroendocrine markers in BON carcinoid cells.

Science.gov (United States)

Ning, Li; Chen, Herbert; Kunnimalaiyaan, Muthusamy

2010-05-01

We have recently reported that activation of the Raf-1/mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase 1/2 (MEK1/2)/ERK1/2 signaling cascade in gastrointestinal carcinoid cell line (BON) alters cellular morphology and neuroendocrine phenotype. The mechanisms by which Raf-1 mediates these changes in carcinoid cells are unclear. Here, we report that activation of the Raf-1 signaling cascade in BON cells induced the expression of focal adhesion kinase (FAK) protein, suppressed the production of neuroendocrine markers, and resulted in significant decreases in cellular adhesion and migration. Importantly, inactivation of MEK1/2 by 1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio]butadiene or abolition of FAK induction in Raf-1-activated BON cells by targeted siRNA led to reversal of the Raf-1-mediated reduction in neuroendocrine markers and cellular adhesion and migration. Phosphorylation site-specific antibodies detected the phosphorylated FAK(Tyr407), but not FAK(Tyr397), in these Raf-1-activated cells, indicating that FAK(Tyr407) may be associated with changes in the neuroendocrine phenotype. Overexpression of constitutively active FAK plasmids (wild-type FAK or FAK(Tyr397) mutant) into BON cells reduced neuroendocrine markers, whereas the FAK(Tyr407) mutant plasmid did not show any decrease in the levels of neuroendocrine markers, indicating that phosphorylation of FAK at the Tyr(407) residue may be important for these effects. Our results showed for the first time that FAK is an essential downstream effector of the Raf-1/MEK1/2/ERK1/2 signaling cascade and negatively regulated the neuroendocrine and metastatic phenotype in BON cells. (c)2010 AACR.

Cytoplasmic vacuolation in cultured rat astrocytes induced by an organophosphorus agent requires extracellular signal-regulated kinase activation

International Nuclear Information System (INIS)

Isobe, Ichiro; Maeno, Yoshitaka; Nagao, Masataka; Iwasa, Mineo; Koyama, Hiroyoshi; Seko-Nakamura, Yoshimi; Monma-Ohtaki, Jun

2003-01-01

There are various toxic chemicals that cause cell death. However, in certain cases deleterious agents elicit various cellular responses prior to cell death. To determine the cellular mechanisms by which such cellular responses are induced is important, but sufficient attention has not been paid to this issue to date. In this study, we showed the characteristic effects of an organophosphorus (OP) agent, bis(pinacolyl methyl)phosphonate (BPMP), which we synthesized for the study of OP nerve agents, on cultured rat astrocytes. Morphologically, BPMP induced cytoplasmic vacuolation and stellation in the rat astrocytes. Cytoplasmic vacuolation is a cell pathological change observed, for example, in vacuolar degeneration, and stellation has been reported in astrocytic reactions against various stimuli. By pretreatment with cycloheximide, a protein synthesis inhibitor, stellation was inhibited, although vacuolation was not. Cell staining with a mitochondrion-selective dye indicated that the vacuolation probably occurs in the mitochondria that are swollen and vacuolatred in the center. Interestingly, the extracellular signal-regulated kinase (ERK) cascade inhibitor inhibited vacuolation and, to some extent, stellation. These results suggest that the ERK signaling cascade is important for the induction of mitochondrial vacuolation. We expect that a detailed study of these astrocytic reactions will provide us new perspectives regarding the variation and pathological significance of cell morphological changes, such as vacuolar degeneration, and also the mechanisms underlying various neurological disorders

Detection of phosphorylated mitogen-activated protein kinase in the developing spinal cord of the mouse embryo

International Nuclear Information System (INIS)

Teraishi, Toshiya; Miura, Kenji

2011-01-01

Highlights: → We detected physiologically phosphorylated MAPKs in developing spinal cord. → We detected physiologically phosphorylated MAPKs by an improved method. → p-ERK1/2 and p-JNK1/2 were detected in the marginal layer and the dorsal horn. → p-ERK1/2 and p-JNK1/2 might play critical roles in the developing spinal cord. → Constructing phosphoprotein atlases will be possible if expanding this work. -- Abstract: Global understanding of the proteome is a major research topic. The comprehensive visualization of the distribution of proteins in vivo or the construction of in situ protein atlases may be a valuable strategy for proteomic researchers. Information about the distribution of various proteins under physiological and pathological conditions should be extremely valuable for the basic and clinical sciences. The mitogen-activated protein kinase (MAPK) cascade plays an essential role in intracellular signaling in organisms. This cascade also regulates biological processes involving development, differentiation, and proliferation. Phosphorylation and dephosphorylation are integral reactions in regulating the activity of MAPKs. Changes in the phosphorylation state of MAPKs are rapid and reversible; therefore, the localizations of physiologically phosphorylated MAPKs in vivo are difficult to accurately detect. Furthermore, phosphorylated MAPKs are likely to change phosphorylated states through commonly used experimental manipulations. In the present study, as a step toward the construction of in situ phosphoprotein atlases, we attempted to detect physiologically phosphorylated MAPKs in vivo in developing spinal cords of mice. We previously reported an improved immunohistochemical method for detecting unstable phosphorylated MAPKs. The distribution patterns of phosphorylated MAPKs in the spinal cords of embryonic mice from embryonic day 13 (E13) to E17 were observed with an improved immunohistochemical method. Phosphorylated extracellular signal-regulated

RAS/ERK modulates TGFβ-regulated PTEN expression in human pancreatic adenocarcinoma cells

OpenAIRE

Chow, Jimmy Y.C.; Quach, Khai T.; Cabrera, Betty L.; Cabral, Jennifer A.; Beck, Stayce E.; Carethers, John M.

2007-01-01

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is rarely mutated in pancreatic cancers, but its regulation by transforming growth factor (TGF)-β might mediate growth suppression and other oncogenic actions. Here, we examined the role of TGFβ and the effects of oncogenic K-RAS/ERK upon PTEN expression in the absence of SMAD4. We utilized two SMAD4-null pancreatic cell lines, CAPAN-1 (K-RAS mutant) and BxPc-3 (WT-K-RAS), both of which express TGFβ surface receptors. Cells were t...

Regulation of myosin light chain kinase during insulin-stimulated glucose uptake in 3T3-L1 adipocytes.

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Shelly Woody

Full Text Available Myosin II (MyoII is required for insulin-responsive glucose transporter 4 (GLUT4-mediated glucose uptake in 3T3-L1 adipocytes. Our previous studies have shown that insulin signaling stimulates phosphorylation of the regulatory light chain (RLC of MyoIIA via myosin light chain kinase (MLCK. The experiments described here delineate upstream regulators of MLCK during insulin-stimulated glucose uptake. Since 3T3-L1 adipocytes express two MyoII isoforms, we wanted to determine which isoform was required for insulin-stimulated glucose uptake. Using a siRNA approach, we demonstrate that a 60% decrease in MyoIIA protein expression resulted in a 40% inhibition of insulin-stimulated glucose uptake. We also show that insulin signaling stimulates the phosphorylation of MLCK. We further show that MLCK can be activated by calcium as well as signaling pathways. We demonstrate that adipocytes treated with the calcium chelating agent, 1,2-b (iso-aminophenoxy ethane-N,N,N',N'-tetra acetic acid, (BAPTA (in the presence of insulin impaired the insulin-induced phosphorylation of MLCK by 52% and the RLC of MyoIIA by 45% as well as impairing the recruitment of MyoIIA to the plasma membrane when compared to cells treated with insulin alone. We further show that the calcium ionophore, A23187 alone stimulated the phosphorylation of MLCK and the RLC associated with MyoIIA to the same extent as insulin. To identify signaling pathways that might regulate MLCK, we examined ERK and CaMKII. Inhibition of ERK2 impaired phosphorylation of MLCK and insulin-stimulated glucose uptake. In contrast, while inhibition of CaMKII did inhibit phosphorylation of the RLC associated with MyoIIA, inhibition of CAMKIIδ did not impair MLCK phosphorylation or translocation to the plasma membrane or glucose uptake. Collectively, our results are the first to delineate a role for calcium and ERK in the activation of MLCK and thus MyoIIA during insulin-stimulated glucose uptake in 3T3-L1 adipocytes.

Unsaturated fatty acids promote proliferation via ERK1/2 and Akt pathway in bovine mammary epithelial cells

International Nuclear Information System (INIS)

Yonezawa, Tomo; Haga, Satoshi; Kobayashi, Yosuke; Katoh, Kazuo; Obara, Yoshiaki

2008-01-01

GPR40 has recently been identified as a G protein-coupled cell-surface receptor for long-chain fatty acids (LCFAs). The mRNA of the bovine ortholog of GPR40 (bGPR40) was detected by RT-PCR in cloned bovine mammary epithelial cells (bMEC) and in the bovine mammary gland at various stages of lactation. Oleate and linoleate caused an increase in intracellular Ca 2+ concentrations in these cells, and significantly reduced forskolin-induced cAMP concentrations. Phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 and Akt kinase, which regulates cell proliferation and survival, was rapidly increased by oleate. Incubation with oleate and linoleate for 24 h significantly promoted cell proliferation. Moreover, in serum-free medium, oleate significantly stimulated cell proliferation during a 7-day culture. These results suggest that bGPR40 mediates LCFA signaling in mammary epithelial cells and thereby plays an important role in cell proliferation and survival