Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

When mesenchymal precursor cells from bone marrow are cultured in the presence of dexamethasone, the existence of distinct non-adherent and adherent populations can be demonstrated. The addition of PGE2, forskolin, or dibutyryl-cAMP can induce a transition from the former to the latter and this may be an important mechanism in the bone anabolic effects of PGE2. On the other hand, phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C, and sulprostone, an agonist for the PGE2 receptor EP1/EP3 subtypes, had no effect. The phosphodiesterase inhibitor, isobutylmethylxanthine (IBMX), had a synergistic effect in combination with PGE2, whereas neomycin, an inhibitor of inositol phosphate activity, had no effect, and LiC1, an inhibitor of inositol triphosphate metabolism, had an inhibitory effect on the PGE2-induced transition. Consistent with this, the addition of PGE2 to non-adherent bone marrow cells caused a 100% increase in cAMP synthesis. These results suggest that the induction of the transition from non-adherent to adherent osteoblast precursor is mediated by the EP2-PGE2 receptor subtype via an increase in intracellular cAMP synthesis.
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PMID:PGE2 induces the transition from non-adherent to adherent bone marrow mesenchymal precursor cells via a cAMP/EP2-mediated mechanism. 748 Aug 6

Inflammatory mediators such as prostaglandin E2 (PGE2) and interleukin-1 (IL-1) induce angiogenesis by yet undefined mechanisms. We demonstrate that PGE2 and IL-1 induces the expression of vascular endothelial growth factor (VEGF), a selective angiogenic factor by rheumatoid synovial fibroblast cells. Transcripts for the EP1 and EP2 subtypes of PGE receptors are expressed in synovial fibroblasts. Activators of protein kinase A pathway stimulated the expression of VEGF whereas down-regulation of protein kinase C did not influence the PGE effect, suggesting that signalling from the EP2 receptor via the protein kinase A pathway is important. The induction of VEGF expression by PGE2 and interleukin-1 alpha may be an important mechanism in inflammatory angiogenesis.
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PMID:Induction of vascular endothelial growth factor expression in synovial fibroblasts by prostaglandin E and interleukin-1: a potential mechanism for inflammatory angiogenesis. 755 49

We examined the signal transduction of mouse prostaglandin E receptor EP1 subtype using Chinese hamster ovary cells stably expressing the cloned EP1. Sulprostone, an EP1 agonist, induced a rapid increase in intracellular Ca2+ concentration in the EP1-expressing cells. Most of the increase was abolished by removal of extracellular Ca2+, and was insensitive to U-73122, a phospholipase C inhibitor. Sulprostone stimulated phosphatidylinositol hydrolysis, but this stimulation was abolished by removal of extracellular Ca2+, indicating that EP1-stimulated phosphatidylinositol hydrolysis is the result of extracellular Ca2+ influx. Thus, the signal transduction of EP1 is extracellular Ca2+ entry through a pathway independent of phospholipase C activation. We further examined the regulation of the signal transduction of EP1 having potential phosphorylation sites for either protein kinase C or protein kinase A. Short-term exposure of the cells to 12-O-tetradecanoylphorbol 13-acetate (TPA) completely suppressed the sulprostone-induced increase in intracellular Ca2+ concentration, while forskolin or dibutyryl cAMP did not affect it, suggesting that protein kinase C but not protein kinase A is involved in the regulation of the EP1 signal transduction. Furthermore, long-term exposure to TPA decreased PGE2 protein kinase A is involved in the regulation of the EP1 signal transduction. Furthermore, long-term exposure to TPA decreased PGE2 binding activity of EP1 due to the reduction of the EP1 mRNA level. Protein kinase C induces short- and long-term desensitization of EP1.
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PMID:Characterization of the signal transduction of prostaglandin E receptor EP1 subtype in cDNA-transfected Chinese hamster ovary cells. 776 67

We have documented new observations with respect to PGE2 action in the rabbit CCD. (1) PGE2 can inhibit both cAMP and vasopressin-induced water flow, depending on the sequence of PGE2 addition with respect to vasopressin or cAMP. (2) PGE2 inhibition of vasopressin or cAMP-stimulated water flow can be reversed with staurosporine. Thus, PGE2 inhibits vasopressin-stimulated water flow by activation of PKC and (3) PGE2 induces release of calcium from intracellular stores. These results strongly suggest the presence of a PGE2 receptor coupled to PIP2 hydrolysis. PGE2 mediated increases in cytosolic calcium are responsible for the inhibitory action of PGE2 on sodium transport. While stimulation of cAMP production by PGE2 may contribute to the inhibition of sodium transport, it is not required since in the presence of 8-CPTcAMP, PGE2 still decreases sodium transport. The effect of PGE2 on sodium transport is pertussis toxin insensitive and is unlikely to be mediated by an inhibitory G protein. Using PGE2 and one of its selective analogues, sulprostone, we have provided evidence for functionally distinct PGE2 receptors. Separate PGE2 receptor subtypes appear to be coupled to separate transport processes. These receptor subtypes may correspond to the EP1, EP2 and EP3 receptors described earlier in smooth muscle. Thus, an EP2 like receptor stimulates cAMP generation and water reabsorption while an EP1 like receptor increases [Ca++]i and inhibits sodium reabsorption. Finally, an EP3 receptor, equivalently activated by sulprostone and PGE2, may couple to Gi and mediate pertussis toxin sensitive inhibition of vasopressin-stimulated water flow.
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PMID:Cellular signalling of PGE2 and its selective receptor analogue sulprostone in rabbit cortical collecting duct. 782 28

Co-expression of EP2 and EP3 subtypes of prostaglandin E2 (PGE2) receptors (R) by U937 human monocytic cells permitted comparative studies of desensitization of each subtype. Specific binding of [3H]PGE2 to membranes of U937 cells showed a Kd of 2.9 +/- 0.3 nM (mean +/- SEM) and a Bmax of 40.5 +/- 1.0 fmol/mg protein, and was competitively inhibited by PGE2 > or = PGE1 > PGF2 alpha > PGD2 > PGI2. EP2 R and EP3 R mRNA were detected by reverse transcription-polymerase chain reaction and Northern blots. EP3 R expression was demonstrated by inhibition of [3H]PGE2 binding with the EP1/EP3 agonist sulprostone [50% inhibitory concentration (IC50 = 3.3 +/- 0.6 nM)] and the EP3/EP2 agonist M&B 28767 (IC50 = 2.1 +/- 0.3 nM), but not with the EP1 antagonist SC-19220. EP2 R protein was identified by Western blot analysis using specific rabbit IgG antibodies to an amino-terminal peptide of the EP2 R. EP2 R transduced PGE2 stimulation of significant increases in cellular [cAMP]i [50% effective concentration (EC50 = 20 +/- 2.5 nM)], and EP3 R mediated sulprostone inhibition of forskolin elevation of [cAMP]i (IC50 = 1.3 +/- 0.4 nM). Pretreatment of U937 cells with phorbol 12-myristate 13-acetate (PMA), which activates protein kinase C (PKC), for 1 hr reduced the total number, but not the affinity, of PGE2 R by down-regulating principally EP2 R. In contrast, a 24-hr exposure to PMA, which is known to down-regulate PKC, suppressed both the total number and affinity of PGE2 R on U937 cells with concurrent reductions in EP2 R and EP3 R. The down-regulation of EP2 R by PMA at 1 hr was blocked by staurosporine, an inhibitor of PKC, whereas the down-regulation of EP3 R by PMA at 24 hr was blocked by indomethacin. Pretreatment of U937 cells with PGE2 for 1 and 24 hr reduced both the binding affinity and the total number of PGE2 R, by co-ordinate suppression of the EP2 R and EP3 R. Desensitization of EP2 R and EP3 R for 1 hr with PGE2 suppressed subsequent PGE2-evoked chemokinetic responses to PGE2, whereas selective down-regulation of EP2 R alone by PMA for 1 hr had no effects on U937 cell migration. Thus expression of each subtype of PGE2 R is regulated independently and EP3 R, but not EP2 R, transduces PGE2 effects on migration of mononuclear phagocytes.
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PMID:Independent down-regulation of EP2 and EP3 subtypes of the prostaglandin E2 receptors on U937 human monocytic cells. 856 30

PKN is a newly discovered protein kinase that has been shown to mediate GTPase Rho dependent intracellular signalling. We show in this report that the mouse PKN gene is situated at the mouse EP1 prostanoid receptor gene locus and that the two genes are overlapping in a tail-to-tail manner. An "exon trap" strategy was used to identify the overlap phenomenon. By using RT-PCR and 3' RACE we have identified two major PKN transcripts that are produced by alternative polyadenylation. The 3' end of the short PKN transcript overlaps the 3' untranslated region of the EP1 gene with approximately 280 bp, while the long PKN transcript overlaps the whole EP1 gene. Remarkably, none of the three transcripts originating from this locus display the consensus AAUAAA polyadenylation signal. The last seven exons of the PKN gene, corresponding to the last third of the PKN cDNA, have been recognised in 7.2 kb of continuous genomic sequence that we have collected from the EP1/PKN genetic locus. The 3' part of the PKN gene is highly fragmented and its intron/exon organisation is reminiscent of that of the Drosophila protein kinase C gene. The possibility of a natural antisense regulation of these genes is discussed.
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PMID:The mouse genes for the EP1 prostanoid receptor and the PKN protein kinase overlap. 885 5

In the present report, we show that prostaglandin (PG) E2 is the most potent factor which stimulates aromatase expression via cyclic AMP and promoter II. PGE2 acts via EP1 and EP2 receptor subtypes to stimulate both the PKC and PKA pathways. The combined stimulation of both of these pathways results in maximal expression of promoter II-specific CYP19 transcripts. Since PGE2 is a major secretory product both of breast tumor epithelial cells and fibroblasts, as well as of macrophages infiltrating the tumor site, then this could be the mechanism whereby estrogen biosynthesis is stimulated in breast sites adjacent to a tumor, leading in turn to increased growth and development of the tumor itself.
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PMID:Estrogen biosynthesis proximal to a breast tumor is stimulated by PGE2 via cyclic AMP, leading to activation of promoter II of the CYP19 (aromatase) gene. 894 Apr 10

Although the exact mechanism of prostaglandin E2 (PGE2)-mediated cytoprotection has not been elucidated, its ability to induce cytoprotection in cell culture suggests this action occurs at the cellular level. The present studies were conducted to determine whether PGE2 induces protection against 2,3,5-(trisglutathion-S-yl)-hydroquinone [2,3,5-(trisglutathion-S-yl)-HQ]-mediated cytotoxicity in a renal proximal tubule epithelial cell line (LLC-PK1) and to delineate the cellular and molecular mechanisms associated with this response. Pretreatment of LLC-PK1 cells with 0.01-40 microM PGE2 for 24 h fully protects against a moderately toxic concentration of 2,3,5-(trisglutathion-S-yl)-HQ. PGE2-mediated cytoprotection is observed in cells pretreated at pH 7.4 but not at pH 7.8. However, cytoprotection is observed in LLC-PK1 cells pretreated with the PGE2 analog, 11-deoxy-16,16-dimethyl PGE2 (DDM-PGE2) but not with the PGE2 receptor [E-prostanoid (EP)] agonists 17-phenyltrinor PGE2 (EP1), 11-deoxy PGE1 (EP2/EP4), sulprostone (EP1/EP3), PGE1, or PGA2. 12-O-tetradecanoylphorbol-13-acetate (TPA), a potent activator of protein kinase C (PKC), also induces cytoprotection, supporting a role for this pathway in the cytoprotective response. PGE2, DDM-PGE2, and TPA all induce the binding of nuclear proteins to a TPA responsive element (TRE), whereas analogs that did not induce cytoprotection (PGE1, 17-phenyltrinor PGE2, sulprostone) were without effect. DDM-PGE2- and TPA-mediated cytoprotection and TRE binding activity are inhibited by N-(2[[3-(4-bromophenyl)-2-propenyl]-amino]-ethyl)-5-isoquinolinesulfonam ide (H-89), a PKC inhibitor. These data suggest that cytoprotection by PGE2 and DDM-PGE2 in LLC-PK1 cells is mediated by a PKC-coupled receptor, which is pharmacologically distinct from the presently classified EP receptor subtypes.
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PMID:PGE2-mediated cytoprotection in renal epithelial cells: evidence for a pharmacologically distinct receptor. 936 28

Estrogen biosynthesis in adipose tissue increases with age and obesity, and has been implicated in the development of endometrial cancer and breast cancer. In normal human adipose tissue, expression of the CYP19 gene which encodes aromatase P450, the enzyme responsible for estrogen biosynthesis, is regulated by a distal promoter, namely promoter I.4. Stimulation of expression in adipose stromal cells by members of the type 1 cytokine family, i.e. interleukin (IL)-6, IL-11, leukemia inhibitory factor (LIF) and oncostatin M (OSM), is mediated via a Jak-STAT3 signaling pathway and a GAS element upstream of promoter I.4. In contrast, aromatase expression in breast adipose tissue proximal to tumor is increased three- to four-fold to the utilization of another promoter, namely promoter II, proximal to the translation initiation site. In the present report, we show that prostaglandin (PG) E2 is the most potent factor which stimulates aromatase expression via cyclic AMP and promoter II. PGE2 acts via EP1 and EP2 receptor subtypes to stimulate both the PKC and PKA pathways. The combined stimulation of both of these pathways results in the maximal expression of promoter II-specific CYP19 transcripts. Because PGE2 is a major secretory product both of breast tumor epithelial cells and fibroblasts, as well as of macrophages infiltrating the tumor site, then this could be the mechanism whereby estrogen biosynthesis is stimulated in breast sites adjacent to a tumor, leading in turn to increased growth and development of the tumor itself.
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PMID:Transcriptional regulation of CYP19 gene (aromatase) expression in adipose stromal cells in primary culture. 936 91

We previously showed that prostaglandin E2 (PGE2) stimulates multiple intracellular signaling pathways as follows: by activation of adenylate cyclase; phosphoinositide (PI)-hydrolyzing phospholipase C and phosphatidylcholine (PC)-hydrolyzing phospholipase D; and by induction of Ca2+ influx in osteoblast-like MC3T3-E1 cells. In this study, we investigated the effect of PGE2 on the synthesis of interleukin-6 (IL-6) and its regulatory mechanism in MC3T3-E1 cells. PGE2 significantly stimulated IL-6 secretion in a dose-dependent manner in the range between 1 nmol/L and 10 micromol/L. A23187, a calcium ionophore, or dibutyryl-cAMP significantly induced IL-6 secretion. The effect of a combination of A23187 and dibutyryl-cAMP on IL-6 secretion was additive. The depletion of extracellular Ca2+ by EGTA reduced the PGE2-induced IL-6 secretion. EP1 receptor antagonist inhibited the PGE2-induced IL-6 secretion. H-89, an inhibitor of cAMP-dependent protein kinase, decreased the PGE2-induced IL-6 secretion. EP2 receptor agonist alone stimulated IL-6 secretion. However, EP4 receptor antagonist had little effect on IL-6 secretion. Calphostin C, a specific inhibitor of protein kinase C (PKC), enhanced the secretion of IL-6 induced by PGE2. The stimulative effect of PGE2 on IL-6 secretion was significantly enhanced in PKC downregulated MC3T3-E1 cells. Pertussis toxin enhanced PGE2-induced IL-6 secretion. These results strongly suggest that PGE2 stimulates IL-6 synthesis through both Ca2+ mobilization from extracellular space via EP1 receptor and cAMP production via EP2 receptor in osteoblast-like cells, and that the PKC activation by PGE2 itself regulates oversynthesis of IL-6.
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PMID:Interleukin-6 synthesis induced by prostaglandin E2: cross-talk regulation by protein kinase C. 955 35


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