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C Pathway (c + pathway)
Kinds of C Pathway Selected AbstractsInhibitory Effects of Ethanol on Rat Mesangial Cell Proliferation via Protein Kinase C PathwayALCOHOLISM, Issue 3 2002Kayoko Segawa A large body of evidence has shown that ethanol inhibits the cell growth and cell proliferation in a variety of cell types. However, it has not been studied whether ethanol inhibits the proliferation of mesangial cells (MC) in the kidney. We examined the effects of ethanol on cell proliferation in cultured rat MC. Treatment with ethanol (10,200 mM) for 48 hr inhibited [3H]thymidine incorporation into MC in a concentration-dependent manner. The same concentrations of ethanol also inhibited the increase in cell number of MC. GF109203X and chelerythrine chloride, inhibitors for protein kinase C, eliminated the inhibitory effects of ethanol; and protein kinase C activator, PMA, mimicked the effects of ethanol. In contrast, neither the protein kinase A inhibitor H-89 nor the protein kinase G inhibitor KT5823 had any effect. These findings suggest that ethanol has inhibitory effects on the proliferation of MC, probably via activation of the protein kinase C pathway. [source] Cyclooxygenase-2 Expression and Prostaglandin E2 Production in Response to Acidic pH Through OGR1 in a Human Osteoblastic Cell Line,,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 7 2008Hideaki Tomura Abstract Acidosis has been shown to induce depletion of bone calcium from the body. This calcium release process is thought to be partially cell mediated. In an organ culture of bone, acidic pH has been shown to induce cyclooxygenase-2 (COX-2) induction and prostaglandin E2 (PGE2) production, resulting in stimulation of bone calcium release. However, the molecular mechanisms whereby osteoblasts sense acidic circumstances and thereby induce COX-2 induction and PGE2 production remain unknown. In this study, we used a human osteoblastic cell line (NHOst) to characterize cellular activities, including inositol phosphate production, intracellular Ca2+ concentration ([Ca2+]i), PGE2 production, and COX-2 mRNA and protein expression, in response to extracellular acidification. Small interfering RNA (siRNA) specific to the OGR1 receptor and specific inhibitors for intracellular signaling pathways were used to characterize acidification-induced cellular activities. We found that extracellular acidic pH induced a transient increase in [Ca2+]i and inositol phosphate production in the cells. Acidification also induced COX-2 induction, resulting in PGE2 production. These proton-induced actions were markedly inhibited by siRNA targeted for the OGR1 receptor and the inhibitors for Gq/11 protein, phospholipase C, and protein kinase C. We conclude that the OGR1/Gq/11/phospholipase C/protein kinase C pathway regulates osteoblastic COX-2 induction and subsequent PGE2 production in response to acidic circumstances. [source] Coupling of Canine Serotonin 5-HT1B and 5-HT1D Receptor Subtypes to the Formation of Inositol Phosphates by Dual Interactions with Endogenous Gi/o and Recombinant G,15 ProteinsJOURNAL OF NEUROCHEMISTRY, Issue 3 2000Thierry Wurch Abstract: Molecular cloning and expression of canine (ca) serotonin 5-HT1B and ca 5-HT1D receptor subtypes showed that besides the lower binding affinity of ketanserin for the ca 5-HT1D receptor, the ligand binding profiles were similar to their human homologues. Site-directed mutagenesis studies suggest that a Gln189 residue in the second extracellular loop of the ca 5-HT1D receptor may partially account for the lower binding affinity of ketanserin. The coupling of ca 5-HT1B and ca 5-HT1D receptor subtypes to the phospholipase C pathway was analyzed by measuring stimulation of inositol phosphate formation in COS-7 cells. Zolmitriptan potently stimulated (EC50 = 4.9 nM) the inositol phosphate formation at ca 5-HT1D receptors in a fully pertussis toxin (PTX)-dependent manner, whereas only a weak PTX-resistant inositol phosphate response (26-29% at 10 ,M zolmitriptan) could be detected for the ca 5-HT1B receptor at a similar expression level. In contrast, both ca 5-HT1B and ca 5-HT1D receptor subtypes yielded a similar maximal magnitude of inositol phosphate formation (300-340% at 10 ,M zolmitriptan) upon co-expression with a mouse (m) G,15 protein. PTX treatment and co-expression with a ,-adrenergic receptor kinase C-terminal polypeptide partially (20-46%) abolished the m G,15 protein-dependent ca 5-HT1B and ca 5-HT1D receptor-mediated stimulation of inositol phosphate formation. This study suggests both 5-HT receptor subtypes can activate ,, subunits of endogenous Gi/o proteins besides their coupling to recombinant m G,15 protein. [source] Inhibitory Effects of Ethanol on Rat Mesangial Cell Proliferation via Protein Kinase C PathwayALCOHOLISM, Issue 3 2002Kayoko Segawa A large body of evidence has shown that ethanol inhibits the cell growth and cell proliferation in a variety of cell types. However, it has not been studied whether ethanol inhibits the proliferation of mesangial cells (MC) in the kidney. We examined the effects of ethanol on cell proliferation in cultured rat MC. Treatment with ethanol (10,200 mM) for 48 hr inhibited [3H]thymidine incorporation into MC in a concentration-dependent manner. The same concentrations of ethanol also inhibited the increase in cell number of MC. GF109203X and chelerythrine chloride, inhibitors for protein kinase C, eliminated the inhibitory effects of ethanol; and protein kinase C activator, PMA, mimicked the effects of ethanol. In contrast, neither the protein kinase A inhibitor H-89 nor the protein kinase G inhibitor KT5823 had any effect. These findings suggest that ethanol has inhibitory effects on the proliferation of MC, probably via activation of the protein kinase C pathway. [source] Chemotherapeutic agents doxorubicin and epirubicin induce a procoagulant phenotype on endothelial cells and blood monocytesJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 4 2009L. L. SWYSTUN Summary.,Background: Although chemotherapy is associated with an increased risk of thrombosis, the pathogenic mechanisms by which chemotherapeutic agents exert prothrombotic effects are unclear. Objectives: In this study we explored the possibility that chemotherapeutic agents doxorubicin, epirubicin, 5-fluorouracil and methotrexate induce a procoagulant phenotype on vascular endothelial cells and/or on blood monocytes. Methods: Thrombin generation was measured in defibrinated plasma exposed to chemotherapy-treated human umbilical vein endothelial cells (HUVECs). Tissue factor activity assays were performed on chemotherapy-treated HUVECs and blood monocytes. The effects of chemotherapy drugs on phosphatidylserine exposure and the protein C pathway were also measured. Results: Exposure of defibrinated plasma to either doxorubicin- or epirubicin-treated HUVECs resulted in an increase in plasma thrombin generation. The procoagulant activity of doxorubicin- and epirubicin-treated HUVECs reflects an increase in tissue factor activity and phosphatidylserine exposure. Doxorubicin-mediated increase in tissue factor activity is related to increased levels of phosphatidylserine rather than to protein disulfide isomerase activity, and is likely to involve reactive oxygen species generation. Unlike doxorubicin, epirubicin does not have an impact on the protein C anticoagulant pathway. Interestingly, neither methotrextate nor 5-fluorouracil altered endothelial or monocyte hemostatic properties. Conclusions: These studies suggest that doxorubicin and epirubicin have the greatest ,prothrombotic potential' by virtue of their ability to alter endothelial and monocyte hemostatic properties. [source] The constitutive and inducible expression of Nurr1, a key regulator of dopaminergic neuronal differentiation, in human neural and non-neural cell linesNEUROPATHOLOGY, Issue 4 2002Jun-ichi Satoh Nur-related factor 1 (Nurr1), nerve growth factor-induced gene B (NGFI-B) and neuron-derived orphan receptor-1 (NOR-1) constitute the orphan nuclear receptor subfamily of transcription factors. Previous studies showed that midbrain dopaminergic neuronal precursor cells failed to differentiate in Nurr1-deficient mice. To investigate a role of Nurr1 in human neuronal function, Nurr1 mRNA expression was studied in human neural cell lines by RT-PCR and northern blot analysis. Nurr1, NGFI-B and NOR-1 mRNA were coexpressed in all human neural and non-neural cell lines under the serum-containing culture condition, except for SK-N-SH neuroblastoma, in which Nurr1 mRNA was undetectable. The levels of Nurr1, NGFI-B and NOR-1 mRNA were elevated markedly in NTera2 teratocarcinoma-derived neurons (NTera2-N), a model of differentiated human neurons, following a 1.5 or 3 h-exposure to 1 mm dibutyryl cyclic AMP or 100 nm phorbol 12-myristate 13-acetate. NGFI-B mRNA levels were also elevated in NTera2-N cells by exposure to 100 ng/mL brain-derived neurotrophic factor (BDNF). To identify Nurr1-target genes, the mRNA expression of 27 genes potentially involved in dopaminergic neuronal differentiation and survival, including BDNF, glia-derived neurotrophic factor, their receptors, tyrosine hydroxylase and ,-synuclein, were studied in HEK293 cells following overexpression of Nurr1. None of these genes examined, however, showed significant changes. These results indicate that Nurr1, NGFI-B and NOR-1 mRNA are expressed constitutively in various human neural and non-neural cell lines under the serum-containing culture condition, and their levels are up-regulated in human neurons by activation of protein kinase A or protein kinase C pathway, although putative coactivators expressed in dopaminergic neuronal precursor cells might be required for efficient transcriptional activation of Nurr1-target genes. [source] Phase II study of bryostatin 1 and vincristine for aggressive non-Hodgkin lymphoma relapsing after an autologous stem cell transplant,AMERICAN JOURNAL OF HEMATOLOGY, Issue 8 2009Paul M. Barr Bryostatin 1, isolated from a marine bryozoan, enhances the efficacy of cytotoxic agents through modulation of the protein kinase C pathway and is active in combination with vincristine for diffuse large B-cell lymphoma. Further, the apoptotic frequency of peripheral blood T lymphocytes as determined by flow cytometry may predict which patients will respond to this combination. We tested the efficacy and safety of bryostatin 1 50 ,g/m2 given over 24 hr and vincristine 1.4 mg/m2 on days 1 and 15 every 28 days in aggressive B-cell non-Hodgkin lymphoma (NHL) relapsing after autologous stem cell transplantation. End points included tumor response, toxicity, and survival. Responses were correlated with an increase in apoptotic frequency of CD5+ cells by flow cytometry using annexin V staining. Fourteen patients were enrolled with 13 being evaluable for a response. The overall response rate was 31% with two patients achieving a complete response. The most common toxicities were Grade 3 lymphopenia (seven patients), Grade 3 to 4 neutropenia (two patients), and Grade 3 hypophosphatemia (two patients). Median progression-free and overall survivals for all patients were 5.7 and 21.4 months, respectively. One patient demonstrated an increase in T-cell apoptotic frequency, also achieving a complete response. Bryostatin 1 and vincristine have efficacy in select patients with aggressive NHL. Future investigations of agents targeting the protein kinase C pathway may benefit from early response assessment using flow cytometry to evaluate T-cell apoptosis. Am. J. Hematol., 2009. © 2009 Wiley-Liss, Inc. [source] Emodin Inhibits Voltage-Dependent Potassium Current in Guinea Pig Gallbladder Smooth MuscleBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 3 2009Zhi-Xuan Wu We studied the effects of emodin on the contraction of gallbladder smooth muscle and voltage-dependent K+ current in gallbladder smooth muscle cells. Gallbladder muscle strips were obtained from adult guinea pigs and the resting tension was recorded. Gallbladder smooth muscle cells were isolated by enzymatic digestion, and K+ current was recorded by the whole-cell patch clamp method. Emodin increased the resting tension of gallbladder smooth muscle strips and inhibited voltage-dependent K+ current in a dose-dependent manner. When 10 µM emodin was applied to gallbladder smooth muscle cells for 3,6 min., the amplitude of voltage-dependent K+ current was decreased by 31.5 ± 0.5% at +40 mV, and this inhibitory effect mostly recovered after washout. The steady-state inactivation curves were shifted in a hyperpolarizing direction by emodin. In the presence of the protein kinase C inhibitors staurosporine and chelerythrine, the effect of emodin on voltage-dependent K+ current was significantly attenuated. In conclusion, emodin promotes gallbladder contraction, mainly by inhibiting voltage-dependent K+ current via the protein kinase C pathway. These findings provide theoretical foundation for the application of emodin in gallbladder motility disorders. [source] Activation of phospholipase C pathways by a synthetic chondroitin sulfate-E tetrasaccharide promotes neurite outgrowth of dopaminergic neuronsJOURNAL OF NEUROCHEMISTRY, Issue 2 2007Naoki Sotogaku Abstract In dopaminergic neurons, chondroitin sulfate (CS) proteoglycans play important roles in neuronal development and regeneration. However, due to the complexity and heterogeneity of CS, the precise structure of CS with biological activity and the molecular mechanisms underlying its influence on dopaminergic neurons are poorly understood. In this study, we investigated the ability of synthetic CS oligosaccharides and natural polysaccharides to promote the neurite outgrowth of mesencephalic dopaminergic neurons and the signaling pathways activated by CS. CS-E polysaccharide, but not CS-A, -C or -D polysaccharide, facilitated the neurite outgrowth of dopaminergic neurons at CS concentrations within the physiological range. The stimulatory effect of CS-E polysaccharide on neurite outgrowth was completely abolished by its digestion into disaccharide units with chondroitinase ABC. Similarly to CS-E polysaccharide, a synthetic tetrasaccharide displaying only the CS-E sulfation motif stimulated the neurite outgrowth of dopaminergic neurons, whereas a CS-E disaccharide or unsulfated tetrasaccharide had no effect. Analysis of the molecular mechanisms revealed that the action of the CS-E tetrasaccharide was mediated through midkine-pleiotrophin/protein tyrosine phosphatase , and brain-derived neurotrophic factor/tyrosine kinase B receptor pathways, followed by activation of the two intracellular phospholipase C (PLC) signaling cascades: PLC/protein kinase C and PLC/inositol 1,4,5-triphosphate/inositol 1,4,5-triphosphate receptor signaling leading to intracellular Ca2+ concentration-dependent activation of Ca2+/calmodulin-dependent kinase II and calcineurin. These results indicate that a specific sulfation motif, in particular the CS-E tetrasaccharide unit, represents a key structural determinant for activation of midkine, pleiotrophin and brain-derived neurotrophic factor-mediated signaling, and is required for the neuritogenic activity of CS in dopaminergic neurons. [source] Differential In Vitro Secretion of Gonadotropin-Releasing Hormone (GnRH) and [Hydroxyproline9]GnRH from the Rat Hypothalamus During Postnatal DevelopmentJOURNAL OF NEUROENDOCRINOLOGY, Issue 9 2000L. Rochdi Abstract The differential secretion of gonadotropin-releasing hormone (GnRH) and [hydroxyproline9]GnRH (HypGnRH) has been recently reported from the adult rat hypothalamus. We report here in vitro cosecretion of HypGnRH and GnRH by the hypothalamus of 2,45 day-old-rats and provide evidence that they are differentially regulated throughout development. The secretion of both forms of GnRH was increased in a dependent manner during depolarization by high K+ solutions, and was stimulated by forskolin and 12- O -tetradecanoylphorbol-13-acetate (TPA), activators of adenylate cyclase and protein kinase C pathways, respectively. The proportion of HypGnRH in the release of GnRH-like peptides remained stable and high (33,40%) under basal and K+ -induced conditions until days 13 and 21, respectively. By contrast, the proportion of HypGnRH in the total GnRH-like content of the developing hypothalamus continuously decreased (from 37% to 14%). Similarly, the proportion of HypGnRH: total GnRH-like material released remained stable in TPA- (30%) and forskolin- (50%) induced secretion until postnatal day 8. Evaluation of release over tissue store ratios revealed a 1.3-to 2.8-fold higher release of HypGnRH compared to GnRH according to the different secretions and postnatal periods examined. The preferential recruitment of HypGnRH was maintained under basal and K+ conditions during postnatal development, but it disappeared under TPA stimulation from day 13 onwards. After forskolin stimulation, the preferential mobilization of HypGnRH was markedly reduced from day 2 to day 13 but recovered its high perinatal level during puberty. Taken together, our results support the hypothesis that HypGnRH may play a specific role in development. In addition, a specific function of this peptide taking place during puberty through the activation of the adenylate cyclase pathway is suggested. [source] Possible role of the protein kinase C/CPI-17 pathway in the augmented contraction of human myometrium after gestationBRITISH JOURNAL OF PHARMACOLOGY, Issue 7 2003Hiroshi Ozaki Activation of protein kinase C (PKC) by phorbol 12,13-dibutylate (PDBu, 1 ,M) induced sustained contractions with no increase in [Ca2+]i in nonpregnant and pregnant human myometria. The contractile effects of PDBu in pregnant myometrium were much greater than those in nonpregnant myometrium, and the contractions in pregnant myometrium were accompanied by an increase in myosin light chain (MLC) phosphorylation at Ser19. The contraction induced by PDBu in pregnant myometrium was inhibited by the inhibitors of conventional PKC isoforms, bisindolylmaleimides and indolocarbazole, such as Go6976, Go6983, and Go6850 (1 ,M). LY333531 (1 ,M), a specific inhibitor of PKC,, also inhibited the PDBu-induced contraction in the pregnant myometrium. In the pregnant myometrium permeabilized with , -toxin, PDBu increased the contractions induced at fixed Ca2+ concentration (0.3 ,M) both in nonpregnant and pregnant myometria, indicating Ca2+ sensitization of contractile elements. Western immunoblot analysis indicated that pregnant myometrium contained PKC isozymes such as conventional PKC (,, ,, ,), novel PKC (,, ,, ,), and atypical PKC (, but not , and ,). RT-PCR and real-time RT-PCR analysis indicated that, among the conventional PKC, the levels of mRNA of , isoform in pregnant human myometrium were greater than those in nonpregnant myometrium. CPI-17 is a substrate for PKC, and the phosphorylated CPI-17 is considered to inhibit myosin phosphatase. The levels of CPI-17 mRNA and protein expression were also greater in the pregnant myometrium. These results suggest that the PKC-mediated contractile mechanism is augmented in human myometrium after gestation, and that this augmentation may be attributable to the increased activity of the , PKC isoform and CPI-17. British Journal of Pharmacology (2003) 140, 1303,1312. doi:10.1038/sj.bjp.0705552 [source] Protein kinase D2 potentiates MEK/ERK/RSK signaling, c-Fos accumulation and DNA synthesis induced by bombesin in Swiss 3T3 cellsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2007James Sinnett-Smith Protein kinase D (PKD) plays an important role in mediating cellular DNA synthesis in response to G protein-coupled receptor (GPCR) agonists but the function of other isoforms of the PKD family has been much less explored. Here, we examined whether PKD2 overexpression in Swiss 3T3 cells facilitates DNA synthesis and the activation of the extracellular regulated protein kinase (ERK) pathway in response to the mitogenic GPCR agonist bombesin. We show that PKD2 overexpression markedly potentiated the ability of this agonist to induce DNA synthesis. Addition of bombesin to Swiss 3T3 cells overexpressing PKD2 also induced a striking increase in the duration of MEK/ERK/RSK activation as compared with cultures of control cells. In contrast, neither DNA synthesis nor the duration of ERK activation in response to epidermal growth factor, which acts via protein kinase C/PKD2-independent pathways, was increased. Furthermore, bombesin promoted a striking accumulation of c-Fos protein in cells overexpressing PKD2. Our study demonstrates that PKD2, like PKD, facilitates mitogenesis and supports the hypothesis that an increase in the duration of the ERK signaling leading to accumulation of immediate gene products is one of the mechanisms by which isoforms of the PKD family enhance re-initiation of DNA synthesis by Gq-coupled receptor activation. J. Cell. Physiol. 211: 781,790, 2007. © 2007 Wiley-Liss, Inc. [source] | |||||||||||||