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)

Progestin regulation of gene expression was assessed in the progestin-dependent murine tumor line C4HD which requires MPA, a synthetic progestin, for in vivo growth and expresses high levels of progesterone receptor (PR). By using suppressive subtractive hybridization, caveolin-1 was identified as a gene whose expression was increased with in vivo MPA treatment. By Northern and Western blot analysis, we further confirmed that caveolin-1 mRNA and protein expression increased in MPA-treated tumors as compared with untreated tumors. When primary cultures of C4HD cells were treated in vitro with MPA, caveolin-1 levels also increased, effect that was abolished by pre-treatment with progestin antagonist RU486. In addition, MPA promoted strong caveolin-1 promoter transcriptional activation both in mouse and human breast cancer cells. We also showed that MPA regulation of caveolin-1 expression involved in activation of two signaling pathways: MAPK and PI-3K. Short-term MPA treatment of C4HD cells led to tyrosine phosphorylation of caveolin-1 protein, where Src was the kinase involved. Additionally, we showed that MPA-induced association of caveolin-1 and PR, which was detected by coimmunoprecipitation and by confocal microscopy. Finally, we proved that MPA-induced proliferation of C4HD cells was inhibited by suppression of caveolin-1 expression with antisense oligodeoxynucleotides to caveolin-1 mRNA. Furthermore, we observed that inhibition of caveolin-1 expression abrogated PR capacity to induced luciferase activity from a progesterone response element-driven reporter plasmid. Comprehensively, our results demonstrated for the first time that caveolin-1 expression is upregulated by progestin in breast cancer. We also demonstrated that caveolin-1 is a downstream effector of MPA that is partially responsible for the stimulation of growth of breast cancer cells.
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PMID:Progestin-induced caveolin-1 expression mediates breast cancer cell proliferation. 1679 39

Recently, a unique family of membrane progestin receptors (mPRalpha, mPRbeta, and mPRgamma) was identified, which may be responsible for mediating rapid, nongenomic actions of progestins in a variety of target tissues. In this study, the mPRalpha and mPRbeta isoforms from zebrafish were shown to be rapidly and specifically activated by the maturation-inducing steroid (MIS) of this species, 4-pregnen-17,20beta-diol-3-one (17,20beta-DHP). The zebrafish mPRalpha and a previously uncharacterized mPRbeta isoform were stably expressed in nuclear progesterone receptor-deficient mammalian breast cancer cells, MDA-MB-231. Expression and surface localization of the receptors were verified by flow cytometry, biotin surface labeling, and Western blotting. Plasma membrane proteins from mPRalpha- or mPRbeta-transfected cells showed high affinity (mPRalpha, K(d) 7 nM; mPRbeta, K(d) 12 nM), saturable, displaceable, single-binding sites specific for 17,20beta-DHP, whereas negligible specific 17,20beta-DHP binding was observed in nontransfected cells. Progestin treatment caused significant activation of mitogen-activated protein kinase (MAPK) within 5 min in cells transfected with either of the receptors as measured by western blotting and flow cytometry. The rank order of the potencies of several progestins in activating MAPK via mPRalpha and mPRbeta was the same (17,20beta-DHP>progesterone >4-pregnen-17,20beta,21-triol-3-one). Interestingly, the MIS in zebrafish, 17,20beta-DHP, was also the most potent inhibitor, among the progestins tested, of adenylyl cyclase activity in cells transfected with either of the receptors. This progestin significantly decreased cAMP levels in both mPRalpha- and mPRbeta-transfected cells in a dose-responsive and time-dependent manner. In addition, signaling of the zebrafish mPRalpha was blocked by pertussis toxin, implying activation of a G(i) protein, while sensitivity to pertussis or cholera toxin was not shown with mPRbeta-mediated signaling, possibly indicating that this receptor activates a different pertussis toxin-insensitive G protein. The results of this study suggest that zebrafish mPRalpha and mPRbeta signal similarly upon progestin binding resulting in rapid activation of MAPK and downregulation of adenylyl cyclase activity.
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PMID:Cell-surface expression, progestin binding, and rapid nongenomic signaling of zebrafish membrane progestin receptors alpha and beta in transfected cells. 1689 59

Human progesterone receptor (PR) contains a motif that interacts with the SH3 domain of Src and mediates rapid activation of Src and downstream MAPK (Erk-1/-2) without relying on the transcriptional activity of the receptor. Here we investigated the role and intracellular location of this nontranscriptional activity of PR. Progestin activation of Src/MAPK occurred outside the nucleus with the B isoform of PR that was distributed between the cytoplasm and nucleus, but not with PR-A that was predominantly nuclear. Breast cancer cells stably expressing wild-type PR-B or PR-B with disrupting point mutations in the SH3 domain binding motif (PR-BDeltaSH3) that do not affect the transcriptional activity of PR, were compared for effects of progestin on endogenous target gene expression and cell proliferation. Progestin induction of the cyclin D1 gene, which lacks a progesterone response element, was dependent on PR activation of the Src/MAPK pathway, whereas induction of the Sgk (serum and glucocorticoid regulated kinase) gene that contains a functional progesterone response element was unaffected by mutations that interfere with PR activation of Src. Progestin induction of cell cycle progression was also abrogated in cells expressing PR-BDeltaSH3, and no effect of progestin on cyclin D1 expression and cell cycle was observed in the presence of PR-A. These results highlight the importance of PR activation of the Src/MAPK signaling pathway for progesterone-induced transcription of select target genes and cell cycle progression.
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PMID:The role of extranuclear signaling actions of progesterone receptor in mediating progesterone regulation of gene expression and the cell cycle. 1713 44

Full-grown Xenopus oocytes are arrested at the prophase of the first meiotic division in a G(2)-like state. Progesterone triggers meiotic resumption also called the G(2)/M transition. This event is characterized by germinal vesicle breakdown (GVBD) and by a burst in phosphorylation level that reflects activation of M-phase-promoting factor (MPF) and MAPK pathways. Besides phosphorylation and ubiquitin pathways, increasing evidence has suggested that the cytosolic and nucleus-specific O-GlcNAc glycosylation also contributes to cell cycle regulation. To investigate the relationship between O-GlcNAc and cell cycle, Xenopus oocyte, in which most of the M-phase regulators have been discovered, was used. Alloxan, an O-GlcNAc transferase inhibitor, blocked G(2)/M transition in a concentration-dependent manner. Alloxan prevented GVBD and both MPF and MAPK activations, either triggered by progesterone or by egg cytoplasm injection. The addition of detoxifying enzymes (SOD and catalase) did not rescue GVBD, indicating that the alloxan effect did not occur through reactive oxygen species production. These results were strengthened by the use of a benzoxazolinone derivative (XI), a new O-GlcNAc transferase inhibitor. Conversely, injection of O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino-N-phenylcarbamate, an O-GlcNAcase inhibitor, accelerated the maturation process. Glutamine:fructose-6-phosphate amidotransferase inhibitors, azaserine and 6-diazo-5-oxonorleucine, failed to prevent GVBD. Such a strategy appeared to be inefficient; indeed, UDP-GlcNAc assays in mature and immature oocytes revealed a constant pool of the nucleotide sugar. Finally, we observed that cyclin B2, the MPF regulatory subunit, was associated with an unknown O-GlcNAc partner. The present work underlines a crucial role for O-GlcNAc in G(2)/M transition and strongly suggests that its function is required for cell cycle regulation.
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PMID:O-linked N-acetylglucosaminyltransferase inhibition prevents G2/M transition in Xenopus laevis oocytes. 1732 55

Mast cells proliferate in vivo in areas of active fibrosis, during parasite infestations, in response to repeated immediate hypersensitivity reactions and in patients with mastocytosis. We investigated how progesterone reduces the proliferation of HMC-1(560) mast cells that proliferate spontaneously in culture. Cells were incubated with 1 microM to 1 nM progesterone for 24-48 h. Progesterone (1 microM) reduced the spontaneous proliferation of HMC-1(560) mast cells to half that of cells cultured without hormone. [(3)H] thymidine incorporation was only 50% of control; there were fewer cells in G2/M and more cells in G0/G1. The amounts of phospho-Raf-1 (Tyr 340-341) and phospho-p42/p44 MAPK proteins were also reduced. In contrast progesterone had no effect on MAP kinase-phosphatase-1. The Raf/MAPK pathway, which depends on Src kinase activity, is implicated in the control of cell proliferation. HMC-1(560) cells incubated with the tyrosine kinase inhibitor PP1 proliferated more slowly than controls and had less phospho-Raf-1 (Tyr 340-341) and phospho-p42/p44 MAPK. The Csk homologous kinase (CHK), an endogenous inhibitor of Src protein tyrosine kinases, was also enhanced in progesterone-treated cells. In contrast, progesterone had no effect on the growth of cells transfected with siRNA CHK. We conclude that progesterone increases the amount of csk homologous kinase, which in turn reduces HMC-1(560) mast cell proliferation. This effect parallels decreases in the phosphorylated forms of Raf-1 and p42/44 MAPK, as their production depends on Src kinase activity.
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PMID:Progesterone increases csk homologous kinase in HMC-1560 human mast cells and reduces cell proliferation. 1749 61

Human progesterone receptors (PR) rapidly activate cytosolic signaling pathways, in addition to their classical function as ligand-activated transcription factors. Using ER+/PR-B+ T47D breast cancer cells, we probed the role of progestin-stimulated rapid PR signaling in the transcriptional regulation of target genes involved in breast cancer cell proliferation. Epidermal growth factor receptor (EGFR) was rapidly activated after a 10-min treatment with R5020. Progestin induced EGFR-, c-Src-, and MAPK-dependent phosphorylation of PR-B on the MAPK consensus site, Ser345. Ser345-phosphorylated PR-B receptors strongly associated with specificity protein 1 (Sp1) transcription factors to regulate PR cell cycle (p21) and growth-promoting (EGFR) target genes whose promoters lack canonical progesterone response element sequences. Inhibitors of EGFR, c-Src, or MAPK activities blocked PR tethering to Sp1 and progestin-stimulated S-phase entry. Mutant PR-B receptors defective for c-Src binding (mPro) were not phosphorylated on Ser345 in response to progestin and failed to interact with Sp1. Hormone-induced complexes containing Sp1 and wild-type PR-B, but not S345A or mPro PR-B, were recruited to Sp1 sites within the endogenous p21 promoter. Progestin-induced S-phase entry was attenuated in T47D cells containing wild-type PR-B and treated with EGFR, c-Src, or MAPK kinase inhibitors or in T47D cells stably expressing mPro or mutant DNA-binding domain PR-B. In sum, rapid progestin-activated PR signaling leads to PR Ser345 phosphorylation and tethering to Sp1. These events are critical for progestin-stimulated regulation of Sp1 target genes and breast cancer cell proliferation. Our data demonstrate the therapeutic potential for PR-targeted breast cancer treatment by exploiting multiple nodes along the PR signaling pathway, including PR-B, EGFR, c-Src, MAPK, or Sp1.
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PMID:Progesterone receptor rapid signaling mediates serine 345 phosphorylation and tethering to specificity protein 1 transcription factors. 1820 49

Human progesterone receptor (PR) contains a polyproline motif in the amino-terminal domain that interacts with the SH3 domain of Src and mediates rapid activation of c-Src and downstream MAPK (Erk-1/-2) independent of the transcriptional activity of PR. Forcedly target PR to different locations in the cell by use of mutations or tags for different cell compartments showed that progestin activation of Src/MAPK is mediated by PR outside the nucleus. No distinction could be made between the cytoplasm and cell membrane as the site of PR activation of Src. Therefore we can only conclude that this is an extra-nuclear action of PR. Interestingly, the B isoform of PR which is naturally distributed between cytoplasm and nucleus mediated progestin activation of Src/MAPK, whereas PR-A that is predominantly nuclear failed to do so indicating that the two PR isoforms have distinct abilities to mediate rapid activation of signaling pathways. Due to distinct cellular locations, progestin activation of Src/MAPK signaling can regulate selected target genes such as cyclin D1 (CCND1) that lack direct PR binding response elements (PREs). Progestin induction of CCND1 was observed in cells expressing PR-B but not PR-BDeltaSH3 or PR-A and induction in the presence of PR-B was dramatically reduced in the presence of inhibitors of Src or MAPK. In contrast progestin induction of Sgk (serum and glucocorticoid regulated kinase) gene, which contains a classical PRE, was observed with both PR isoforms as well as PR-BDeltaSH3 and was unaffected by Src and MAPK inhibitors. PR bound to enhancer region of Sgk in a progestin dependent manner as detected by chromatin co-immunoprecipitation (ChIP) whereas no PR binding to CCDN1 was observed. Consistent with CCND1 data, progestin stimulation of cell cycle progression was only observed in cells expressing PR-B but not cells expressing PR-BDeltaSH3 or PR-A. These results demonstrate the importance of PR activation of extra-nuclear signaling pathways in regulating selected target genes and cell cycle progression.
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PMID:The role and mechanism of progesterone receptor activation of extra-nuclear signaling pathways in regulating gene transcription and cell cycle progression. 1832 50

The inhibitory effect of 15-methoxypinusolidic acid (15-MPA) isolated from Biota orientalis (Cupressaceae) on lipopolysaccharide (LPS)-induced inflammation in microglial BV2 cells was investigated. 15-MPA significantly reduced the expression of inducible nitric oxide synthase (iNOS), the activity of iNOS, and the production of nitric oxide (NO) in LPS-stimulated BV2 cells. In addition, 15-MPA significantly suppressed the expressions of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and cyclooxygenase (COX)-2. However, 15-MPA did not affect LPS-induced degradation of inhibitor kappaB-alpha (IkappaB-alpha) and translocation of nuclear factor-kappaB (NF-kappaB) into the nucleus. LPS-activated p38 MAPK, extracellular signal-regulated kinase (ERK)-1/2, and stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) were not affected by 15-MPA. Taken together, this study demonstrates that 15-MPA inhibits LPS-induced iNOS expression and NO production, independent on MAPK and NF-kappaB, suggesting a potential anti-inflammatory effect of the compound on microglial cells.
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PMID:A pinusolide derivative, 15-methoxypinusolidic acid from Biota orientalis inhibits inducible nitric oxide synthase in microglial cells: implication for a potential anti-inflammatory effect. 1832 46

Several growth factors, such as vascular endothelial growth factor, brain-derived neurotrophic factor, and insulin-like growth factor-I are involved in the actions of progesterone in the central nervous system. Previous studies in neuronal and glial cultures have shown that progesterone may regulate growth factor signaling, increasing the phosphorylation of extracellular-signal regulated kinase (ERK) and the phosphorylation of Akt, components of the mitogen-activated protein kinase (MAPK) and the phosphoinositide-3 kinase (PI3K) signaling pathways, respectively. In this study, we have evaluated whether progesterone and its reduced metabolites, dihydroprogesterone and tetrahydroprogesterone, regulate PI3K and MAPK signaling in the brain of ovariectomized rats in vivo. Significant increases in the phosphorylation of ERK, in the expression of the catalytic (p110) and the regulatory (p85) subunits of PI3K and in the phosphorylation of Akt were observed in the hypothalamus, the hippocampus, and the cerebellum 24 hr after progesterone administration. Progesterone metabolites partially mimicked the effect of progesterone and had a stronger effect on MAPK and PI3K signaling in the hypothalamus than in the other brain regions. These findings suggest that progesterone regulates MAPK and PI3K signaling pathways in the central nervous system in vivo by direct hormonal actions and by mechanisms involving progesterone metabolites.
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PMID:Regulation of the phosphoinositide-3 kinase and mitogen-activated protein kinase signaling pathways by progesterone and its reduced metabolites in the rat brain. 1875 5

Ovulation-associated inflammation with accompanied cytokines and reproductive hormones impact upon the human ovarian surface epithelium (hOSE) and probably have a role in the aetiology of ovarian cancer. Progesterone and progestin-related events, i.e. pregnancy and oral contraception, protect from the disease. We have investigated the pre-receptor metabolism of progesterone in primary hOSE cells and an immortalised hOSE cell line, OSE-C2, focusing on transcriptional regulation of 3beta-hydroxysteroid dehydrogenase (3beta-HSD) by inflammatory, anti-inflammatory and apoptotic factors. In hOSE cells, we show that anti-inflammatory effects of IL-1alpha and IL-4 on 3beta-HSD2 mRNA involve a p38 MAPK signalling pathway, whereas pro-inflammatory response of IL-1alpha to 3beta-HSD1 mRNA involves a NF-kappaB inflammatory pathway. In OSE-C2 cells, retinoic acid and transforming growth factor-beta1 massively induce 3beta-HSD1 mRNA levels. In conclusion, we elaborate several mechanisms for intracrine formation of progesterone in hOSE that could contribute in the development of novel strategies to prevent, diagnose and/or treat ovarian cancer.
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PMID:3beta-Hydroxysteroid dehydrogenases and pre-receptor steroid metabolism in the human ovarian surface epithelium. 1877 48


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