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)

1. The effects of bradykinin on nociceptors have been characterized on a preparation of the neonatal rat spinal cord with functionally connected tail maintained in vitro. Administration of bradykinin to the tail activated capsaicin-sensitive peripheral fibres and evoked a concentration-dependent (EC50 = 130 nM) depolarization recorded from a spinal ventral root (L3-L5). 2. The response to bradykinin was unaffected by the peptidase inhibitors, bestatin (0.4 mM), thiorphan (1 microM), phosphoramidon (1 microM) and MERGETPA (10 microM) or by the presence of calcium blocking agents, cadmium (200 microM) and nifedipine (10 microM). 3. Inhibition of cyclo-oxygenase with indomethacin (1-5 microM), aspirin (1-10 microM) and paracetamol (10-50 microM) consistently attenuated responses to bradykinin. 4. The effect of bradykinin was mimicked by the phorbol ester PDBu, an activator of protein kinase C. The response to bradykinin was attenuated following desensitization to PDBu but desensitization to bradykinin did not induce a cross-desensitization to PDBu. The protein kinase C inhibitor staurosporine (10-500 nM) consistently attenuated the effects of PDBu and bradykinin. 5. Bradykinin responses were reversibly enhanced by dibutyryl cyclic AMP (100 microM). However dibutyryl cyclic GMP (0.5 mM) and nitroprusside (10 microM) produced prolonged block of responsiveness to bradykinin. Prolonged superfusion with pertussis toxin did not affect responses to bradykinin. 6. The B1-receptor agonist des Arg9-bradykinin (10-100 microM) was ineffective alone or after prolonged exposure of the tail to lipopolysaccharide (100 ng ml-1) or epidermal growth factor (100 ng ml-1) to induce B1 receptors. The BI-receptor antagonist, des Arg9 Leu8-bradykinin (10 JM) did not attenuate the response to bradykinin. A number of bradykinin B2 antagonists selectively and reversibly attenuated the response to bradykinin. The rank order potency was Hoe 140> LysLys [Hyp3,Thi5 8,D-Phe7]-bradykinin> D-Arg[Hyp3, Thi5'8, D-Phe7]-bradykinin = D-Arg[Hyp2,Thi5'8, D-Phe7]-bradykinin.7. These data show that bradykinin produces concentration-dependent activation of peripheral nociceptors in the neonatal rat tail. The responses were unaffected by calcium channel block and were partially dependent on the production of prostanoids. Bradykinin-evoked responses were consistent with the activation of protein kinase C-dependent mechanisms. Cyclic GMP-dependent mechanisms may be involved in bradykinin-receptor desensitization whereas cyclic-AMP dependent mechanisms increase fibre excitability and facilitate bradykinin-induced responses. The effects of bradykinin were mediated by a B2 receptor.
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PMID:Bradykinin-induced activation of nociceptors: receptor and mechanistic studies on the neonatal rat spinal cord-tail preparation in vitro. 133 51

Pyroglutamyl peptidase II (EC 3.4.19.-), a membrane-bound metalloproteinase, is a highly specific TRH-degrading enzyme. Exposure of Y-79 human retinoblastoma cells to 12-0-tetradecanoyl phorbol 13-acetate (TPA) decreased the activity of this enzyme in a time- and concentration-dependent manner (IC50 5 x 10(-9) M). After 15 min of TPA treatment, only 10% of pyroglutamyl peptidase II activity remained. TPA treatment did not affect the activity of the cytosolic enzyme pyroglutamyl peptidase I (EC 3.4.19.3) or the membrane-bound enzyme dipeptidyl peptidase IV (EC 3.4.19.3). Pretreatment of the cells with the protein kinase C inhibitors H-7 or sphingosine prevented the inactivation of pyroglutamyl peptidase II by TPA. The time course of the TPA-mediated effect paralleled the time course of translocation and activation of protein kinase C in this cell line. Immunoblot analysis demonstrated that inactivation of pyroglutamyl peptidase II was not due to dissociation or internalization of this enzyme molecule. Incubation of TPA-activated Y-79 cell membranes with gamma-[32P]-ATP followed by immunoprecipitation revealed a time-dependent phosphorylation of a 48 kilodalton subunit of pyroglutamyl peptidase II. These studies indicate that the phorbol ester effect is mediated by protein kinase C, and reveal a mechanism of potentiation of the action of TRH at its target sites.
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PMID:Rapid inactivation and phosphorylation of pyroglutamyl peptidase II in Y-79 human retinoblastoma cells after exposure to phorbol ester. 197 29

Much is known about intestinal epithelial regulation by growth factors and nutrients but the intracellular signals governing cell phenotype are less well understood. In an initial attempt to evaluate the role of protein kinase C in these events, we studied the effects of protein kinase C modulation by the phorbol ester TPA upon the differentiation, motility, and doubling time of the human intestinal epithelial Caco-2 cell line, a common model for enterocytic brush border enzyme expression. We also compared the effects of TPA to those of 4 alpha-phorbol 12,13-didecanoate, which does not modulate protein kinase C activity. Differentiation was studied by quantitating brush order dipeptidyl peptidase (DPDD)-specific activity in protein-matched Caco-2 lysates via synthetic substrate digestion. Alkaline phosphatase (AP) was studied for comparison. Doubling time was assessed by log transformation of serial cell counts and motility by monolayer expansion across type I collagen. TPA (0.03-0.7 micrograms/ml) dose-dependently stimulated DPDD, with a maximal 455 +/- 26% increase at 0.7 micrograms/ml (P < 0.01, n = 5). However, TPA dose-dependently inhibited AP to a maximal 91.6 +/- 0.3% decrease (P < 0.01, n = 5). TPA also dose-dependently prolonged the cell doubling time from 26.5 +/- 0.4 to 64.5 +/- 8.8 hr (n = 20, P < 0.01) with a maximal effect at 1.0 micrograms/ml and inhibited migration with essentially complete ablation of cell motility at 0.1 micrograms/ml (n = 10, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Specific modulation of intestinal epithelial brush border enzyme expression by a phorbol ester. 763 Jan 14

Pyroglutamyl peptidase II (PPII) is a thyrotropin-releasing hormone (TRH) hydrolyzing ectoenzyme with a narrow specificity. In the adenohypophysis, it is present on lactotropes. This study was undertaken in order to determine whether TRH itself regulates PPII activity in the adenohypophysis. After 5 days in culture, dispersed cells from female pituitaries expressed detectable levels of PPII activity when 10(-8) M 3,3',5'-triiodo-L-thyronine was present throughout the culture. 10(-6) M TRH decreased PPII activity with a maximal effect (down to 46% of initial values) at 16 h and an ED50 of 10(-9) M. [3Me-His2]TRH, a potent agonist of the TRH receptor was effective at lower concentrations (ED50: 1.6 x 10(-10) M). Phorbol-12-myristate-13-acetate (PMA; 10(-6) M), a protein kinase C (PKC) activator, diminished PPII activity to 61% or initial values with an ED50 of 2.2 x 10(-8) M. Maximal effects of PMA and TRH were not additive. Neither PMA nor TRH effects were reversed by inhibitors of protein kinases (1-(5-isoquinolinesulfonyl)-2-methyl-piperazine or sphingosine or staurosporine); TRH-induced downregulation of the enzyme was not modified by PMA pretreatment. TRH had no effect on two other ectopeptidases, endopeptidase 24.11 and dipeptidyl aminopeptidase IV. These data demonstrate that TRH specifically downregulates PPII activity in adenohypophyseal cells through TRH receptor activation and suggest that the activation of a presumably calcium-independent PKC mimics the TRH effect. TRH regulation of PPII activity may contribute to adjust lactotrope responsiveness to TRH.
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PMID:Thyrotropin-releasing hormone downregulates pyroglutamyl peptidase II activity in adenohypophyseal cells. 796 91

Virus infection usually alters the host cell and shuts off the synthesis of cellular macromolecules. In order to screen the upregulated cellular transcripts during pseudorabies virus (PRV) infection, we employed the mRNA differential display technique. The screen is based on positive selection at the mRNA level for genes expressed in normal cells but increased in corresponding PRV-infected cells. Over 14000 species of mRNA, isolated from mock-infected and PRV-infected Madin-Darby bovine kidney cell at 1 h post infection, were screened, and 40 candidate clones were recovered. Southern blot analysis revealed that 17 out of 40 candidate clones, were enhanced in PRV-infected cells. Partial DNA sequences demonstrated that 17 clones were distinct cellular genes, including those encoding the modulators of signal transduction (saposin, 14-3-3, adenylate kinase, adenylyl cyclase, protein kinase C-alpha), those encoding the components of translation (fau, ribosomal proteins S11, L31, L36), other cellular genes (peptidase, cyclin E, rch1, oligo-C-rich single-stranded nucleic acid binding protein, rap, arginyl-tRNA synthetase), and two unknown genes. Thus, this study identifies successfully the transcriptionally regulated cellular genes which are associated with PRV infection. Furthermore, this study provides support for the use of mRNA differential display as a method to rapidly isolate differentially expressed genes in virus infection.
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PMID:Analysis of upregulated cellular genes in pseudorabies virus infection: use of mRNA differential display. 891 Jun 44

We have investigated the effect of UVC irradiation on "TGF alpha ase" activity using both intact HeLa cells and isolated membrane fragments with an assay based on the previously described nonapeptide substrate method [Brown et al. (1992): J Cell Biochem 48:411-423]. This method allows recognition of cleavage at the scissile bond cognate with that of the TGF alpha N-terminal cleavage site from its membrane-bound precursor. The level of ectoendopeptidase (including "TGF alpha ase") activity observed on intact cells was lower than that of ectoaminopeptidases. Addition of foetal bovine serum (FBS) enhanced aminopeptidase and dipeptidyl peptidase activity but inhibited "TGF alpha ase" activity, while phorbol 12-myristate 13-acetate (PMA) had no significant effect on the ectopeptidases monitored, expect for "TGF alpha ase," which was also inhibited, in contradistinction to their effects in other cell systems. Sublethal UVC irradiation (10 Jm-2) of the cultures resulted in activation of the ectoaminopeptidase and ectoendopeptidases which was maximal 16 and 20-24 h after irradiation, respectively. The addition of FBS to these irradiated cells appeared to reduce the increase in endopeptidase products, due in part to increased aminopeptidase activity but also to the direct inhibitory effect of FBS on the "TGF alpha ase." The activation of these proteases by UVC, even at high fluences (500 Jm-2), was not observed within the first 30 min after the cells were irradiated. Purified plasma membrane fragments were prepared from suspension cultures of HeLa cells and displayed high levels of "TGF alpha ase" activity. The rate of "TGF alpha ase" activity using 140 nM peptide substrate (P9) was 5.6 pmol/min/mg membrane protein, which was elevated to 13.7 pmol/min/mg membrane protein, 20 h after the cells had been irradiated with 10 Jm-2 UVC. Inhibition studies indicate that the plasma membrane "TGF alpha ase is a metalloenzyme as it was inhibited by EDTA, EGTA, and 1,10-phenanthroline but not by elastase or serine protease inhibitors. "TGF alpha ase" activity on intact cells was shown to be inhibited by 1,10-phenanthroline, which further supports this suggestion. Treatment of the membranes with Triton X-100 resulted in a loss of "TGF alpha ase" activity, raising the possibility that this enzyme may require a cofactor to be fully functional. We show that in purified membrane preparations of HeLa cells there is evidence for the presence of a "TGF alpha ase" which can be activated by UV irradiation, which differs from the putative "TGF alpha ase" described in various other cell lines, and which does not seem dependent on protein kinase C (PKC) activity.
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PMID:UVC activation of the HeLa cell membrane "TGF alpha ase," a metalloenzyme. 905 93

G-protein coupled receptor (GPCR) agonists such as neuropeptides activate the insulin-like growth factor-1 receptor (IGF-IR) or the serine-threonine protein kinase Akt, suggesting that neuropeptides-GPCR signaling can cross-communicate with IGF-IR-Akt signaling pathways. Neutral endopeptidase 24.11 (NEP) is a cell-surface peptidase that cleaves and inactivates the neuropeptides endothelin-1 (ET-1) and bombesin, which are implicated in progression to androgen-independent prostate cancer (PC). We investigated the mechanisms of NEP regulation of neuropeptide-mediated cell survival in PC cells, including whether neuropeptide substrates of NEP induce phosphorylations of IGF-IR and Akt in PC cells. Western analyses revealed ET-1 and bombesin treatment induced phosphorylation of IGF-IRbeta and Akt independent of IGF-I in TSU-Pr1, DU145, and PC-3 PC cells, which lack NEP expression, but not in NEP-expressing LNCaP cells. Recombinant NEP and induced NEP expression in TSU-Pr1 cells using a tetracycline-repressive expression system inhibited ET-1-mediated phosphorylation of IGF-IRbeta and Akt, and blocked the protective effects of ET-1 against apoptosis induced by serum starvation. Incubation of TSU-Pr1 cells with specific kinase inhibitors together with ET-1 or bombesin showed that IGF-IR activation is required for neuropeptide-induced Akt phosphorylation, and that neuropeptide-induced Akt activation is predominantly mediated by Src and phosphatidylinositol 3-kinase but not by mitogen-activated protein kinase or protein kinase C. These data show that the neuropeptides ET-1 and bombesin stimulate ligand-independent activation of the IGF-IR, which results in Akt activation, and that this cross-communication between GPCR and IGF-IR signaling is inhibited by NEP.
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PMID:Neutral endopeptidase inhibits neuropeptide-mediated transactivation of the insulin-like growth factor receptor-Akt cell survival pathway. 1130 83

Angiotensin II (Ang II) is a bioactive peptide of the renin-angiotensin system, exerting its actions not only as a vasoconstrictor, but also as a growth promoter. In human placenta, type 1 Ang II receptors (AT(1)R) are predominantly expressed in trophoblasts, and we previously reported that aminopeptidase A (APA), a cell surface peptidase that converts Ang II to Ang III, is also expressed in both normal and neoplastic trophoblasts. However, the roles of Ang II and APA in trophoblast function remain to be clarified. In the present study we examined the effects of Ang II on proliferation and APA expression in trophoblast-like BeWo choriocarcinoma cells. Treatment of BeWo cells with Ang II significantly increased DNA synthesis in a dose-dependent manner. Ang II also enhanced APA mRNA and cell surface expression in BeWo cells analyzed by Northern blotting, flow cytometry, and enzyme activity assay. The Ang II-induced proliferation and APA up-regulation were blocked by the AT(1)R antagonist candesartan, but not by the AT(2)R antagonist PD123319. Furthermore, these Ang II effects were abolished by the protein kinase C inhibitor bisindolylmaleimide I and the MAPK inhibitor PD98059. Immunohistochemistry using choriocarcinoma tissues demonstrated that APA was expressed on the cell surface of AT(1)R-positive cytotrophoblastic cells in vivo. With these findings we demonstrate that Ang II stimulates the proliferation of trophoblastic cells via AT(1)R that are linked to protein kinase C /MAPK-dependent signaling pathways, and that the Ang II-degrading enzyme APA is up-regulated during Ang II-induced cell proliferation. These observations suggest the possible regulatory mechanism by the local renin-angiotensin system, especially the Ang II-AT(1)R-APA system, for the growth of human choriocarcinoma cells.
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PMID:Enhancement of aminopeptidase A expression during angiotensin II-induced choriocarcinoma cell proliferation through AT1 receptor involving protein kinase C- and mitogen-activated protein kinase-dependent signaling pathway. 1291 95

The ADAM (a disintegrin and metalloprotease) family consists of multidomain cell-surface proteins that have a major impact on cell behavior. These transmembrane-anchored proteins are synthesized as proforms that have (from the N terminus): a prodomain; a metalloprotease-, disintegrin-like-, cysteine-rich, epidermal growth factor-like, and transmembrane domain; and a cytoplasmic tail. The 90-kDa mature form of human ADAM12 is generated in the trans-Golgi through cleavage of the prodomain by a furin-peptidase and is stored intracellularly until translocation to the cell surface as a constitutively active protein. However, little is known about the regulation of ADAM12 cell-surface translocation. Here, we used human RD rhabdomyosarcoma cells, which express ADAM12 at the cell surface, in a temporal pattern. We report that protein kinase C (PKC) epsilon induces ADAM12 translocation to the cell surface and that catalytic activity of PKCepsilon is required for this translocation. The following results support this conclusion: 1) treatment of cells with 0.1 microM phorbol 12-myristate 13-acetate (PMA) enhanced ADAM12 cell-surface immunostaining, 2) ADAM12 and PKCepsilon could be co-immunoprecipitated from membrane-enriched fractions of PMA-treated cells, 3) RD cells transfected with EGFP-tagged, myristoylated PKCepsilon expressed more ADAM12 at the cell surface than did non-transfected cells, and 4) RD cells transfected with a kinase-inactive PKCepsilon mutant did not exhibit ADAM12 cell-surface translocation upon PMA treatment. Finally, we demonstrate that the C1 and C2 domains of PKCepsilon both contain a binding site for ADAM12. These studies show that PKCepsilon plays a critical role in the regulation of ADAM12 cell-surface expression.
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PMID:Regulation of ADAM12 cell-surface expression by protein kinase C epsilon. 1536 51

The MAP kinase pathway inhibitor U0126 in combination with butyrate promotes differentiation in some colon cancer cell lines. We examined several inhibitors of histone deacetylase (HDAC) in combination with U0126 and other protein kinase inhibitors to see if these effects are general properties of HDAC inhibitors or butyrate alone. Alkaline phosphatase and peptidase activities were examined as markers for cellular differentiation in the human colon cancer cell lines Caco-2 and HT29 and the minimally transformed NCM460. Several HDAC inhibitors caused greater increases of alkaline phosphatase in the cancer cells than in NCM460, in which butyrate was the only HDAC inhibitor that caused a consistent increase. Unlike the JNK and PKC inhibitors examined, the MEK 1/2 inhibitor U0126 induced alkaline phosphatase activity in Caco-2 as a single agent and caused additive effects with HDAC inhibitors. The PI-3 kinase inhibitor LY294002 had little effect alone but enhanced the response of most HDAC inhibitors as did the raf inhibitor GW5074. In addition to butyrate, several HDAC inhibitors can induce differentiation in colon cancer cells and the responses may be enhanced by U0126, GW5074 and LY294002.
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PMID:Induction of differentiation of colon cancer cells by combined inhibition of kinases and histone deacetylase. 1746 97


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