Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.4.3 (phospholipase C)
 18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We sought to establish and immunocytochemically characterize primary cultures of human conjunctival epithelial (HCE) cells, and to determine the types of receptors coupled to adenylate cyclase (AC) and phospholipase C (PLC) present on them which may be stimulated following allergic or inflammatory provocation of the tissue. HCE cells possessed the key epithelial cell surface cytokeratins AE1, AE3 and AE5. Signal transduction studies (n > or = 3), using agonists and antagonists, revealed the presence of beta 2-adrenergic (isoproterenol EC50 = 5.2 nM), prostaglandin E2 (EC50 = 168 nM) and vasoactive intestinal peptide (EC50 = 0.69 nM) receptors positively coupled to AC in HCE cells. Bradykinin (EC50 = 0.83 nM), platelet activating factor (EC50 = 4.5 nM), leukotriene C4 (EC50 = 300 nM) and histamine1 (EC50 = 3.1 microM) receptors were coupled to PLC (n = 3 for each). These data suggest that HCE cells in vivo may represent target cells for mast cell mediators and certain neurotransmitters which are released into the tear-film upon allergic provocation of the conjunctiva.
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PMID:Pharmacological analysis of mast cell mediator and neurotransmitter receptors coupled to adenylate cyclase and phospholipase C on immunocytochemically-defined human conjunctival epithelial cells. 926 68

It is generally accepted that in endothelial cells the occupation of bradykinin B2 receptors, which are linked to the guanine nucleotide-dependent regulatory proteins, Gi and Gq, results in the activation of phospholipase C-beta1 (PLC-beta1), followed by a transient increase in the formation of inositol 1,4,5-trisphosphate (IP3) and diacylglycerol. The PLC-beta1 isoform, in contrast to the gamma1 isoform, is present only at a low level in cultured endothelial cells, implying that PLC-gamma1 activation may play an important role in endothelial signaling pathways. In cultured human endothelial cells, bradykinin induced a rapid increase in the tyrosine phosphorylation of several Triton-soluble proteins. Immunoprecipitation of tyrosine-phosphorylated proteins from bradykinin-stimulated cells followed by Western blotting using the respective antibodies facilitated the identification of a 77 kiloDalton (kDa) protein as paxillin, a 130 kDa protein as PLC-gamma1, and a 42/44 kDa doublet as mitogen-activated protein (MAP) kinase. The bradykinin-induced tyrosine phosphorylation of PLC-gamma1 was relatively transient and was associated with an increase in intracellular levels of IP3. Bradykinin also induced the rapid and transient activation of phosphotyrosine phosphatases localized mainly in the Triton X-100-soluble cell fraction; this tyrosine phosphatase activity was apparently initiated after the release of Ca2+ from intracellular stores.
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PMID:Tyrosine phosphorylation and bradykinin-induced signaling in endothelial cells. 929 62

Bis-diphosphoinositol tetrakisphosphate ([PP]2-InsP4 or 'InsP8') is a 'high-energy' inositol phosphate; we report that its metabolism is receptor-regulated in DDT1 MF-2 smooth muscle cells. This conclusion arose by pursuing the mechanism by which F- decreased cellular levels of [PP]2-InsP4 up to 70%. A similar effect was induced by elevating cyclic nucleotide levels, either with IBMX or by application of either Bt2cAMP (EC50 = 14.7 microM), Bt2cGMP (EC50 = 7.9 microM) or isoproterenol (EC50 = 0.4 nM). Isoproterenol (1 microM) decreased [PP]2-InsP4 levels 25% by 5 min, and 71% by 60 min. This novel, agonist-mediated regulation of [PP]2-InsP4 turnover was very specific; isoproterenol did not decrease the cellular levels of either inositol pentakisphosphate, inositol hexakisphosphate or other diphosphorylated inositol polyphosphates. Bradykinin, which activated phospholipase C, did not affect [PP]2-InsP4 levels. Regulation of [PP]2-InsP4 turnover by both isoproterenol and cell-permeant cyclic nucleotides was unaffected by inhibitors of protein kinases A and G. The effectiveness of the kinase inhibitors was confirmed by their ability to block phosphorylation of the cAMP response element-binding protein. Our results indicate a new signaling action of cAMP, and furnish an important focus for future research into the roles of diphosphorylated inositol phosphates in signal transduction.
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PMID:Turnover of bis-diphosphoinositol tetrakisphosphate in a smooth muscle cell line is regulated by beta2-adrenergic receptors through a cAMP-mediated, A-kinase-independent mechanism. 950 Oct 92

Bradykinin (BK) B2 receptor signaling involves activation of phospholipase C (PLC). PLC activation by other receptors consists of either allosteric activation of PLC beta isoforms by G-proteins or tyrosine phosphorylation of PLC gamma isoforms. Because the B2 receptor is a G-protein-coupled receptor, it has been assumed that the receptor signals through PLC beta. In the present study, however, we have found that BK stimulation of IP3 production and the Ca2+ signal in endothelial cells is dependent on tyrosine phosphorylation. Furthermore, stimulation of B2 receptors in these cells is accompanied by a transient tyrosine phosphorylation of PLC gamma 1. Phosphorylation is correlated with increased IP3 production and association of PLC gamma 1 with the C-terminal intracellular domain of the B2 receptor. The B2 receptor can thus physically associate with intracellular proteins other than G-proteins. Activation of PLC gamma isoforms, rather than PLC beta isoforms, may, therefore, be primarily responsible for BK-stimulated IP3 generation in endothelial cells.
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PMID:Bradykinin stimulates the tyrosine phosphorylation and bradykinin B2 receptor association of phospholipase C gamma 1 in vascular endothelial cells. 960 70

We studied the mechanisms underlying the bradykinin-evoked changes in intracellular calcium concentration ([Ca2+]i) in Madin Darby canine kidney (MDCK) cells. Bradykinin evoked a [Ca2+]i transient in a dose-dependent manner, measured by fura-2 fluorimetry and digital video imaging. The transient consisted of a rise and a decay and [Ca2+]i returned to baseline without oscillations. External Ca2+ influx occurred, as demonstrated by Mn2+ quench and external Ca2+ removal measurements. Bradykinin acted by stimulating bradykinin B2 receptors as evidenced by blockade by D-arginyl-L-arginlyl-L-prolyl-trans-4-hydroxy-L-prolylglycyl -3-(2-thienyl)-L-alanyl-L-seryl-D-1,2,3,4-tetrahydro-3-isoquinolineca rbonyl-L-(2alpha,3beta,7alphabeta)-octahydro-1 H-indole-2-carbonyl-L-arginine (HOE 140) but not by D-arginyl-L-arginlyl-L-prolyl-trans-4-hydroxy-L-proylglycyl- 3-(2-thienyl)-L-alanyl-L-seryl-D-1,2,3,4-tetrahydro-3-isoquinolinecar bonyl-L-(2alpha,3beta,7alphabeta)-octahydro-1 H-indole-2-carbonyl ([Des-Arg]HOE 140). The [Ca2+]i signal was abolished by 1-(6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1 H-pyrrole-2,5-dione (U73122) and partially inhibited by neomycin, implying mediation by phospholipase C. The transient was initiated by a release of Ca2+ from internal stores since it was abolished by pretreatment with thapsigargin or cyclopiazonic acid. The mobilization of the internal Ca2+ store subsequently triggered a 1-[beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1 H-imidazole hydrochloride (SKF 96365)-insensitive Ca2+ entry. Pretreatment with carbonylcyanide m-chlorophynylhydrozone and gly-phe-beta-naphthylamide did not alter the transient, thus excluding the participation of mitochondria and lysosomes. Efflux via Ca2+ pumps contributed to the decay of the transient. Efflux via Na+/Ca2+ exchange or sequestration by mitochondria and lysosomes was insignificant. The transient was blunted by the protein kinase C activator phorbol 12-myristate 13-acetate, and was enhanced by the protein kinase C inhibitors sphingosine and chelerythrine, the protein kinase A inhibitor 2,5-di-(t-butyl)-1,4-hydroquinone, N-[2-(p-bromocinnamylamino)ethyl]5-isoquinolinesulfonamide (H-89), the agent 8-(diethylamino)octyl 3,4,5-trimethoxybenzoate (TMB-8), and agents that elevated levels of 3',5'-cyclic guanosine monophosphate. The transient did not heterologously desensitize with that evoked by ATP, ADP or UTP.
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PMID:Bradykinin-evoked Ca2+ mobilization in Madin Darby canine kidney cells. 976 37

Bradykinin (BK) plays a key role in collecting duct functions. Using an established line of principal cells of the rabbit collecting duct (R.C. SV3), we examined the characteristics of the BK receptors in these cells. [3H]-BK bound specifically to R.C. SV3. Saturation binding analyses allowed KD (968 +/- 232 pM) and Bmax values (356 +/- 43 fmol/mg protein) to be calculated. Competitive displacement of [3H]-BK was observed with Hoe-140, a specific type 2 BK receptor (BKR-2) antagonist, but not with des arg9-BK, a BKR-1 agonist. The presence of BKR-2 was confirmed by the reverse-transcription polymerase chain reaction technique. BK stimulated cytosolic calcium and inositol phosphate formation in a dose-dependent manner (from 1 nM to 1 microM). BK also inhibited the arginine vasopressin dependent increase of cyclic adenosine monophosphate. This effect could not be related to the production of prostaglandin E2. These results demonstrate the presence of high-affinity BKR-2 in the principal cells of the rabbit collecting duct that are linked to phospholipase C activity and are involved in arginine vasopressin related regulatory loops.
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PMID:Characterization of B2-bradykinin receptors in rabbit principal cells of the collecting duct. 980 25

The effect of bradykinin on the cytosolic Ca2+ concentration were measured in single, Fura-2 loaded, smooth muscle cells isolated from rat duodenum. All cells responded with a Ca2+ signal when exposed to bradykinin. The bradykinin response consisted of an initial Ca2+ spike followed by a plateau. Pre-treatment of single muscle cells with either the phospholipase C blocker U-73122 or thapsigargin, which is a potent inhibitor of the endoplasmic reticulum Ca2+-ATPase, inhibited the response to bradykinin. Pre-treatment of the cells with EGTA or La3+ to inhibit the Ca2+ influx, abolished the response induced by bradykinin. We conclude that bradykinin applied to single smooth muscle cells from rat duodenum, increases cytosolic Ca2+ by emptying intracellular Ca2+ stores, and by contribution from extracellular Ca2+. In contrast to bradykinin-induced response in isolated rat duodenum (a relaxation followed by a contraction), we did not observe a biphasic effect of bradykinin on cytosolic Ca2+ in single muscle cells. Bradykinin may thus cause relaxation of duodenal smooth muscle indirectly through an effect on neighbouring cells as dilatation is brought about by this agent in blood vessels.
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PMID:Bradykinin elevates cytosolic Ca2+ concentration in smooth muscle cells isolated from rat duodenum. 1019 74

1. Differentiation of SH-SY5Y neuroblastoma cells induces morphological and biochemical changes consistent with a more neuronal phenotype. These cells may therefore provide a model for studying phenomena such as signal transduction in a neuronal context whilst retaining the advantages of a homogenous cell population expressing a well characterized array of G-protein coupled receptors. 2. This study examined the effects of differentiating SH-SY5Y cells on muscarinic- and bradykinin-receptor-mediated phosphoinositide and Ca2+ signalling. Retinoic acid (10 microM, 6 days) along with a lowered serum concentration produced phenotypic changes consistent with differentiation including reduced proliferation and increased neurite outgrowth. 3. Differentiation increased the magnitude and potency of rapid Ins(1,4,5)P3 responses to a full muscarinic receptor agonist. Bradykinin receptor-mediated Ins(1,4,5)P3 signalling was also potentiated following differentiation. Determination of agonist-evoked accumulation of [3H]-inositol phosphates under lithium-block demonstrated these changes reflected enhanced phospholipase C activity which is consistent with observed increases in the expression of muscarinic and bradykinin receptors. 4. Despite the marked alterations in Ins(1,4,5)P3 signalling following differentiation, elevations of intracellular [Ca2+] were totally unaltered. Thus, in SH-SY5Y cells, the relationship between the elevations of Ins(1,4,5)P3 and intracellular [Ca2+] is agonist dependent and affected by the state of differentiation. This demonstrates that mechanisms other than the measured increase in Ins(1,4,5)P3 regulate the elevation of intracellular [Ca2+].
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PMID:Complex relationship between Ins(1,4,5)P3 accumulation and Ca2+ -signalling in a human neuroblastoma reveled by cellular differentiation. 1032 87

In a previous publication we provided evidence of a novel neuronal pathway for the control of GnRH secretion by bradykinin. The action of bradykinin appeared to be exerted through the bradykinin B2 receptor. In this study we demonstrated that the bradykinin B2 receptor is densely localized in the arcuate nucleus, median eminence, organum vasculosum of the lamina terminalis, and preoptic area, regions known to be critical for the control of GnRH secretion. To determine the mechanism of action of bradykinin in stimulating GnRH release, we used immortalized GnRH (GT1-7) cells in vitro. Bradykinin stimulation of GnRH secretion from GT1-7 cells appears to involve activation of the phospholipase C signaling pathway and mobilization of extracellular and intracellular calcium stores. Evidence to support this contention was derived from the observations that incubation of the phospholipase C inhibitor, U-73122 with bradykinin, blocked the ability of bradykinin to stimulate release from GT1-7 cells. This effect was specific, as a nitric oxide synthase inhibitor and a cyclooxygenase inhibitor were found to have no effect on bradykinin-induced GnRH secretion, suggesting that nitric oxide and PGs do not mediate bradykinin effects. Pertussis toxin also had no effect on bradykinin action. This suggests that the bradykinin B2 receptor may be coupled to a pertussis toxin-insensitive G protein in GT1-7 cells. With respect to calcium involvement in bradykinin action, fura-2 calcium indicator studies revealed that bradykinin can rapidly increase intracellular Ca2+ levels in GT1-7 cells. A role for intracellular Ca2+ in bradykinin action was further suggested by the finding that an intracellular calcium chelator, 1,2-bis(O-aminophenoxy)]ethane-N,N,N',N'-tetraacetic acid tetraacetoxymethyl ester, significantly attenuated the effects of bradykinin on GnRH release. The elevation of intracellular calcium by bradykinin appears to be due to mobilization of calcium from the endoplasmic reticulum, as incubation of the Ca2+-adenosine triphosphatase inhibitor thapsigarin, which depletes endoplasmic reticulum Ca2+ stores, significantly attenuated bradykinin action on GnRH release. Extracellular calcium may also be involved in bradykinin action, as the L-type Ca2+ channel blockers verapamil and nifedipine had no effect on bradykinin-induced GnRH release, whereas the nonselective Ca2+ channel blocker, nickel chloride, attenuated bradykinin-induced GnRH release. Taken as a whole, these studies demonstrate that the bradykinin B2 receptor is densely localized in key hypothalamic nuclei responsible for regulation of GnRH release, and that the mechanism of bradykinin stimulation of GnRH secretion involves activation of the phospholipase C signaling pathway, with a critical role implicated for calcium in bradykinin action in GT1-7 cells.
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PMID:Bradykinin receptor localization and cell signaling pathways used by bradykinin in the regulation of gonadotropin-releasing hormone secretion. 1049 24

Biochemical signalling events coupled to the bradykinin B(2)-receptor subtype, related to nitric oxide and prostaglandin E(2) generation were studied in rat submandibular gland. Bradykinin stimulation of the B(2)-receptor triggered activation of phosphoinositide turnover, translocation of protein kinase C, stimulation of nitric oxide synthase activity, increased production of cGMP and release of prostaglandin E(2). Bradykinin stimulation of nitric oxide synthase and cGMP production was blunted by agents able to interfere with calcium/calmodulin and phospholipase C activities, while a protein kinase C inhibitor was able to stimulate bradykinin action. Moreover, a specific B(2)-bradykinin antagonist of the reversible nitric oxide synthase inhibitor abrogated the bradykinin stimulation of nitric oxide synthase activity, cGMP accumulation and prostaglandin E(2) generation. Furthermore, a specific inhibitor of phospholipase A(2) blocked the bradykinin-induced prostaglandin E(2) release. These results suggest that apart, from the direct effect of bradykinin as an inducer of vasopermeability, it also appears to be a vasoactive chemical mediator that triggers, through release of prostaglandin E(2), a feedback mechanism that induces a protective adaptation of the gland, modulating the course of inflammation.
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PMID:Involvement of the endogenous nitric oxide signalling system in bradykinin receptor activation in rat submandibular salivary gland. 1086 85


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