Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Communication between endothelial and bone cells is crucial for controlling vascular supply during bone growth, remodeling, and repair but the molecular mechanisms coordinating this intercellular crosstalk remain ill-defined. We have used primary human and rat long bone-derived osteoblast-like cells (HOB and LOB) and human umbilical vein endothelial cells (HUVEC) to interrogate the potential autocrine/paracrine role of vascular endothelial cell growth factor (VEGF) in osteoblast:endothelial cell (OB:EC) communication and examined whether prostaglandins (PG), known modulators of both OB and EC behavior, modify VEGF production. We found that the stable metabolite of PGI2, 6-keto-PGF(1alpha) and PGE2, induced a concentration-dependent increase in VEGF release by HOBs but not ECs. In ECs, VEGF promoted early ERK1/2 activation, late cyclooxygenase-2 (COX-2) protein induction, and release of 6-keto-PGF1alpha. In marked contrast, no significant modulation of these events was observed in HOBs exposed to VEGF, but LOBs clearly exhibited COX-dependent prostanoid release (10-fold less than EC) following VEGF treatment. A low level of osteoblast-like cell responsiveness to exogenous VEGF was supported by VEGFR2/Flk-1 immunolabelling and by blockade of VEGF-mediated prostanoid generation by a VEGFR tyrosine kinase inhibitor (TKI). HOB alkaline phosphatase (ALP) activity was increased following long-term non-contact co-culture with ECs and exposure of ECs to VEGF in this system further increased OB-like cell differentiation and markedly enhanced prostanoid release. Our studies confirm a paracrine EC-mediated effect of VEGF on OB-like cell behavior and are the first supporting a model in which prostanoids may facilitate this unidirectional VEGF-driven OB:EC communication. These findings may offer novel regimes for modulating pathological bone remodeling anomalies through the control of the closely coupled vascular supply.
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PMID:Evaluation of VEGF-mediated signaling in primary human cells reveals a paracrine action for VEGF in osteoblast-mediated crosstalk to endothelial cells. 1768 28

In ruminants, endometrial prostaglandin F(2alpha) (PGF(2alpha)) is the luteolytic hormone. Cellular transport of PGF(2alpha) in the uterine endometrium is critical for regulation of the estrous cycle. Molecular mechanisms responsible for control of PGF(2alpha) transport in endometrium during luteolysis are largely unknown. In the present study, we characterized the prostaglandin transporter (PGT) in ovine endometrium. Ovine PGT cDNA consists of 1935 nucleotides that encode 644 amino acids. In ovine endometria, PGT is highly expressed during the period of luteolysis, between d 14 and 16 of the estrous cycle, in luminal and glandular epithelia. Pharmacological and genomic inhibition of PGT indicates that it is responsible for influx and efflux of PGF(2alpha) in ovine endometrial epithelial cells. Inhibition of PGT during the period of luteolysis prevents the release of oxytocin-induced PGF(2alpha) pulses, and maintains functional corpus luteum and its secretion of progesterone. In ovine endometrial epithelial cells, protein kinase A and protein kinase C pathways are involved in regulating the influx of PGF(2alpha), whereas epidermal growth factor receptor pathways are implicated in regulation of influx and efflux of PGF(2alpha.) The ERK1/2 pathway is associated with efflux of PGF(2alpha), whereas Jun-amino-terminal kinase/stress-activated protein kinase pathways are involved in both efflux and influx of PGF(2alpha.) Phosphatidylinositol 3-kinase pathways are not involved in either influx or efflux of PGF(2alpha) in ovine endometrial epithelial cells. These are the first results to demonstrate a functional role for PGT in regulation of PGF(2alpha) efflux and influx in ovine endometrial cells that influence luteolytic mechanisms in ruminants.
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PMID:Molecular cloning and characterization of prostaglandin (PG) transporter in ovine endometrium: role for multiple cell signaling pathways in transport of PGF2alpha. 1790 Dec 26

FP prostanoid receptors are G-protein-coupled receptors whose physiological activator is prostaglandin-F(2alpha) (PGF(2alpha)). PGF(2alpha) has been implicated in wound healing and cardiac hypertrophy, which are both known to involve the induction of the immediate-early response gene, early growth response factor-1 (EGR-1). We hypothesized that activation of the human FP receptor by PGF(2alpha) could induce the expression of EGR-1 and found that 1 muM PGF(2alpha) produced a time-dependent induction of both mRNA and protein expression for EGR-1. This FP receptor-mediated induction of EGR-1 expression involved activation of the small GTPase Ras followed by activation of C-Raf and the mitogen-activated protein (MAP) kinase kinases 1 and 2 (MEK1/2). Thus, induction of EGR-1 expression by PGF(2alpha) was blocked using dominant-negative constructs of Ras and C-Raf and the Raf kinase inhibitor 4-(4-(3-(4-chloro-3-trifluoromethylphenyl)ureido)phenoxy)-pyridine-2-carboxyllic acid methyamide-4-methylbenzenesulfonate (BAY43-9006). Likewise, the MEK1/2 inhibitor 2'-amino-3'-methoxyflavone (PD98059) blocked the induction of EGR-1 expression by PGF(2alpha). FP receptor stimulation by PGF(2alpha) induced the phosphorylation of C-Raf, MEK1/2, and extracellular signal-regulated kinases 1 and 2, consistent with the activation of a MAP kinase signaling cascade. PGF(2alpha) was also found to induce the expression of EGR-1 in rat cardiomyocytes through the activation of endogenous FP receptors. This induction of EGR-1 expression in cardiomyocytes also involved the activation of Raf and MAP kinase signaling and was dependent on the activation of protein kinase C. This is the first report to show the regulation of EGR-1 expression after PGF(2alpha) activation of FP receptors and suggests that this could be an early event involved in wound healing and cardiac hypertrophy.
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PMID:FP prostanoid receptor-mediated induction of the expression of early growth response factor-1 by activation of a Ras/Raf/mitogen-activated protein kinase signaling cascade. 1791 34

Endothelial dysfunction is associated with endothelial cell activation, i.e., up-regulation of surface cell adhesion molecules and the release of proinflammatory cytokines. 20-Hydroxyeicosatetraenoic acid (HETE), a major vasoactive eicosanoid in the microcirculation, has been implicated in the regulation of endothelial cell function through its angiogenic and pro-oxidative properties. We examined the effects of 20-HETE on endothelial cell activation in vitro. Cells transduced with adenovirus containing either CYP4A1 or CYP4A2 produced higher levels of 20-HETE, and they demonstrated increased expression levels of the adhesion molecule intercellular adhesion molecule (ICAM) (4-7-fold) and the oxidative stress marker 3-nitrotyrosine (2-3-fold) compared with cells transduced with control adenovirus. Treatment of cells with 20-HETE markedly increased levels of prostaglandin (PG) E(2) and 8-epi-isoprostane PGF(2alpha), commonly used markers of activation and oxidative stress, and most prominently, interleukin-8, a potent neutrophil chemotactic factor whose overproduction by the endothelium is a key feature of vascular injury. 20-HETE at nanomolar concentrations increased inhibitor of nuclear factor-kappaB phosphorylation by 2 to 5-fold within 5 min, which was followed with increased nuclear translocation of nuclear factor-kappaB (NF-kappaB). Likewise, 20-HETE activated the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway by stimulating phosphorylation of ERK1/2. Inhibition of NF-kappaB activation and inhibition of ERK1/2 phosphorylation inhibited 20-HETE-induced ICAM expression. It seems that 20-HETE triggers NF-kappaB and MAPK/ERK activation and that both signaling pathways participate in the cellular mechanisms by which 20-HETE activates vascular endothelial cells.
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PMID:20-Hydroxyeicosatetraenoic acid stimulates nuclear factor-kappaB activation and the production of inflammatory cytokines in human endothelial cells. 1794 96

In endometrial adenocarcinomas COX-2 and F-series prostanoid (FP) receptor expression and prostanoid biosynthesis (PGE(2) and PGF(2alpha)) are elevated. In the present study, we investigated the effect of PGE(2) and PGF(2alpha) on the expression of COX-2 via the FP receptor in endometrial adenocarcinoma cells stably expressing the FP receptor (FPS cells). Using chemical inhibitors of intracellular signaling pathways, reporter gene assays and quantitative RT-PCR analysis, we show that PGE(2) and PGF(2alpha) can mobilize inositol 1,4,5-trisphosphate, induce ERK1/2 phosphorylation via the phospholipase Cbeta-protein kinase A-epidermal growth factor receptor pathway and induce cyclooxygenase-2 (COX-2) expression via the FP receptor. In addition we show that the PGE(2) or PGF(2alpha)-regulation of COX-2 via the FP receptor is mediated via the cAMP response element (CRE) binding site on the COX-2 promoter. These data indicate that PGE(2) and PGF(2alpha) biosynthesized locally within endometrial adenocarcinomas can regulate tumor cell function in an autocrine/paracrine manner via the FP receptor.
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PMID:Prostaglandin E2 and F2alpha activate the FP receptor and up-regulate cyclooxygenase-2 expression via the cyclic AMP response element. 1831 57

Studies were designed to examine the roles of individual protein kinase C (PKC) isoforms in the prostaglandin F(2alpha) (PGF(2alpha))-induced matrix metalloproteinase-2 (MMP-2) secretion from human ciliary muscle cells. Studies utilized primary cultures of human ciliary muscle cells. Individual PKC isoforms were detected by Western blotting, using PKC-isoform-specific antibodies. To evaluate MMP-2 secretion, cells were serum-starved overnight, treated with PGF(2alpha) (1 micromol/L) for 4 h and the media analyzed for MMP-2 by Western blotting. To assess ERK1/2 activation, cells were serum-starved overnight, treated with PGF(2alpha) (1 micromol/L) for 5 min and cell lysates analyzed for ERK1/2 phosphorylation by Western blot analysis. To evaluate the roles of individual PKC isoforms, cells were pretreated with PKC inhibitors or siRNAs prior to the addition of PGF(2alpha). In cultured human ciliary muscle cells, the PKC isoforms exhibiting the highest level of expression were PKCalpha, epsilon, iota and lambda. The delta and eta isoforms exhibited moderate levels of expression and beta, gamma, and phi were not detected. The administration of PGF(2alpha) (1 micromol/L) primarily induced the translocation of PKCepsilon from cytosol to the membrane fraction, as well as increased MMP-2 secretion and ERK1/2 phosphorylation. The secretion of MMP-2 was inhibited by pretreatment with the broad-range PKC inhibitor, chelerythrine chloride; however, this response was not blocked by Go-6976, an inhibitor of conventional PKC isoforms. The PGF(2alpha)-induced secretion of MMP-2 was also blocked by pretreatment with the PKCepsilon-selective peptide translocation inhibitor, EAVSLKPT, or the transfection of siRNA-targeting PKCepsilon. The activation of ERK1/2 was inhibited by chelerythrine and the PKCepsilon translocation inhibitor. Human ciliary muscle cells express the alpha, epsilon, iota and lambda PKC isoforms. Stimulation of FP receptors in these cells activates PKCepsilon, resulting in ERK1/2 activation and an eventual increase in MMP-2 secretion. These data support the idea that the activation of FP receptors in vivo modulate uveoscleral outflow through the PKCepsilon-dependent secretion of MMPs.
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PMID:Role of PKCepsilon in PGF2alpha-stimulated MMP-2 secretion from human ciliary muscle cells. 1846 68

We have previously reported that prostaglandin F(2alpha) (PGF(2alpha)) stimulates interleukin-6 (IL-6), a potent bone resorptive agent, through p44/p42 mitogen-activated protein (MAP) kinase in osteoblast-like MC3T3-E1 cells. In the present study, we investigated whether Rho-kinase is implicated in the PGF(2alpha)-stimulated IL-6 synthesis in MC3T3-E1 cells. PGF(2alpha) time-dependently induced the phosphorylation of myosin phosphatase targeting subunit (MYPT-1), a Rho-kinase substrate. Y27632, a specific Rho-kinase inhibitor, significantly reduced the PGF(2alpha)-stimulated IL-6 synthesis as well as the MYPT-1 phosphorylation. Fasudil, another inhibitor of Rho-kinase, suppressed the PGF(2alpha)-stimulated IL-6 synthesis. Y27632 and fasudil failed to affect the PGF(2alpha)-induced phosphorylation of p44/p42 MAP kinase. SB203580 and BIRB0796, potent inhibitors of p38 MAP kinase, suppressed the IL-6 synthesis induced by PGF(2alpha). While SP600125, an inhibitor of stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), failed to reduce the synthesis. Y27632 as well as fasudil attenuated the PGF(2alpha)-induced phosphorylation of p38 MAP kinase. These results strongly suggest that Rho-kinase regulates PGF(2alpha)-stimulated IL-6 synthesis via p38 MAP kinase activation in osteoblasts.
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PMID:Involvement of Rho-kinase in prostaglandin F2alpha-stimulated interleukin-6 synthesis via p38 mitogen-activated protein kinase in osteoblasts. 1858 82

Prostaglandins belong to a class of cyclic lipid-derived mediators synthesized from arachidonic acid via COX-1, COX-2 and various prostaglandin synthases. Members of this family include prostaglandins such as PGE(2), PGF(2alpha), PGD(2) and PGI(2) (prostacyclin) as well as thromboxane. In the present studies we analyzed the effects of UVB on prostaglandin production and prostaglandin synthase expression in primary cultures of undifferentiated and calcium-differentiated mouse keratinocytes. Both cell types were found to constitutively synthesize PGE(2), PGD(2) and the PGD(2) metabolite PGJ(2). Twenty-four hours after treatment with UVB (25 mJ/cm(2)), production of PGE(2) and PGJ(2) increased, while PGD(2) production decreased. This was associated with increased expression of COX-2 mRNA and protein. UVB (2.5-25 mJ/cm(2)) also caused marked increases in mRNA expression for the prostanoid synthases PGDS, mPGES-1, mPGES-2, PGFS and PGIS, as well as expression of receptors for PGE(2) (EP1 and EP2), PGD(2) (DP and CRTH2) and prostacyclin (IP). UVB was more effective in inducing COX-2 and DP in differentiated cells and EP1 and IP in undifferentiated cells. UVB readily activated keratinocyte PI-3-kinase (PI3K)/Akt, JNK and p38 MAP signaling pathways which are known to regulate COX-2 expression. While inhibition of PI3K suppressed UVB-induced mPGES-1 and CRTH2 expression, JNK inhibition suppressed mPGES-1, PGIS, EP2 and CRTH2, and p38 kinase inhibition only suppressed EP1 and EP2. These data indicate that UVB modulates expression of prostaglandin synthases and receptors by distinct mechanisms. Moreover, both the capacity of keratinocytes to generate prostaglandins and their ability to respond to these lipid mediators are stimulated by exposure to UVB.
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PMID:UVB light upregulates prostaglandin synthases and prostaglandin receptors in mouse keratinocytes. 1859 4

Prostaglandin F(2alpha) (PGF(2alpha)) stimulates hypertrophic growth of neonatal rat cardiac myocytes, a feature of which includes downregulation of the Ca(2+)-ATPase (SERCA2), a major Ca(2+) transport protein in SR. The molecular mechanisms by which PGF(2alpha) inhibits SERCA2 gene expression remain unknown. We determined the cis-regulatory elements responsible for the regulation of the SERCA2 gene expression in cultured neonatal rat cardiac myocytes exposed to PGF(2alpha). The role of Egr-1 was evaluated by transient transfection of its expression vector and antisense oligonucleotide. Signaling pathways were determined by using the pharmacological inhibitors or cDNA expression plasmids coding for dominant negative forms of Ras and Rac. PGF(2alpha) reduced the SERCA2 mRNA levels in a time- and dose-dependent manner in cultured rat cardiac myocytes. Transient transfection analyses showed that PGF(2alpha) -responsive elements are located between -284 and -72 of the SERCA2 promoter, which contains G+C-rich sequences homologous to Sp1, Egr-1 and AP2-binding sites. PGF(2alpha) significantly increased Egr-1 expression, and overexpression of Egr-1 largely reduced the transcription of the SERCA2 gene. Egr-1 antisense oligonucleotides blocked the PGF(2alpha) -mediated decrease in SERCA2 mRNA expression. Furthermore, inhibitors for either genistein-sensitive tyrosine kinase or p38 MAPK, and dominant negative forms of either Ras or Rac, prevented PGF(2alpha) -induced repression of SERCA2 mRNA levels. These results suggest that Egr-1, as well as Ras, Rac, and p38 MAPK, plays a crucial role in the repression of SERCA2 gene expression during PGF(2alpha) -induced cardiac hypertrophy.
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PMID:Prostaglandin F2alpha inhibits SERCA2 gene transcription through an induction of Egr-1 in cultured neonatal rat cardiac myocytes. 1861 90

Mangiferin, a naturally occurring glucosylxanthone, has potent antioxidant and anti-inflammatory properties, as demonstrated in several reports. However, very limited information is available on the effects of this natural polyphenol on microglial activation. Thus, the aim of this study was to examine whether mangiferin is able to reduce prostaglandin E(2) (PGE(2)) and 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)) production by lipopolysaccharide (LPS)-activated primary rat microglia. Microglial cells were stimulated with 10ng/ml of LPS in the presence or absence of different concentrations of mangiferin (1-50 microM). After 24h incubation, culture media were collected to measure the production of PGE(2) and 8-iso-PGF(2alpha) using enzyme immunoassays. Protein levels of cyclooxygenase (COX)-1 and COX-2 were studied by immunoblotting after 24h of incubation with LPS. Mangiferin potently reduced LPS-induced PGE(2) synthesis and the formation of 8-iso-PGF(2alpha). Interestingly, mangiferin dose-dependently reduced LPS-induced COX-2 protein synthesis without modifying COX-2 transcription. This was due to a decrease in COX-2 transcript stability. However, mangiferin did not modify LPS-mediated phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK), a key factor involved in enhancing COX-2 mRNA stability and COX-2 translation in primary microglia. Mangiferin had no effects on LPS-induced expression of inducible nitric oxide synthase (iNOS) or TNF-alpha production. Taken together, results from the present study indicate that mangiferin is able to limit microglial activation, in terms of attenuation of PGE(2) production, free radical formation and reduction in COX-2 synthesis induced by LPS. These data suggest that modulation of microglial activation might contribute to the mechanism of cerebral protection by mangiferin.
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PMID:Mangiferin inhibits cyclooxygenase-2 expression and prostaglandin E2 production in activated rat microglial cells. 1862 Oct 15


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