Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The interactions between dopamine and carbachol on the excitatory synaptic transmission were studied in rat neostriatal slices using an intracellular recording method. Excitatory postsynaptic potentials (EPSPs) were evoked by cortical stimulation. Application of dopamine (DA; 0.1 microM) or carbachol (0.1 microM) produced a dramatic and reversible inhibition of the EPSP amplitude. The inhibitory effect induced by carbachol was markedly attenuated in the presence of either DA (0.1 microM) or the selective D2 dopaminergic receptor agonist (+/-)-2-(N-phenylethyl-N-propyl) amino-5-hydroxytertralin (PPHT; 0.1 microM), but not by the D1 dopaminergic receptor agonist (+/-)-7, 8-dihydroxy-3-allyl-1-phenyl-2, 3, 4, 5-tetrahydro-1H-3-benzazepine (SKF-38393; 0.1 microM) or the D3 dopaminergic receptor agonist R(-)-(4aS, 10bS)-3, 4, 4a, 10b-tetrahydro-4-propyl-2H, 5H-[1] benzogyrano-[4,3-b]-1, 4-oxazin-9-ol (PD-128,907; 0.1 microM). Conversely, muscarinic receptor activation with carbachol (0.1 microM) also completely abolished the DA-induced depression of the EPSP amplitude. In addition, the inhibitory effect of DA on the carbachol-induced depression of the EPSP amplitude was antagonized by sulpiride (1 microM), a selective D2 dopaminergic receptor antagonist. However, D1 dopaminergic receptor antagonist (+/-)-7-bromo-8-hydroxy-3-methyl-1-phenyl-2, 3, 4, 5-tetrahydro-3-benzazepine (SKF-83566; 1 microM) did not affect DA's inhibition. Rp-adenosine-3',5'-cyclic monophosphothioate (Rp-cAMPS; 25 microM), a potent inhibitor of cAMP-dependent protein kinase A (PKA), alone decreased the amplitude of EPSP below baseline values and mimicked the inhibitory effect of DA on the carbachol-induced depression of the EPSP amplitude. Based on these findings, we conclude that the inhibitory effects of D2 dopaminergic receptor and muscarinic receptor activation on the excitatory synaptic transmission in the neostriatum are non-additive and therefore are antagonistic interactions. furthermore, the effect of muscarinic receptor stimulation will depend on the extent of D2 dopaminergic receptor activation and the modulation of the cellular PKA-dependent messenger system seems to contribute to their interactions.
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PMID:Mutual inhibitory effects between dopamine and carbachol on the excitatory synaptic transmission in the rat neostriatum. 889 3

1. [3H]Noradrenaline (NA) AND [14C]acetylcholine (ACh) released by electrical field stimulation were measured simultaneously in strips from the body of rat urinary bladder. 2. [3H]NA and [14C]ACh release was greater during continuous stimulation (CS; 10 Hz, 100 shocks) or in the presence of eserine than during intermittent train stimulation (IS; 10 Hz, 10 shocks every 5 s, 10 times). Atropine (1 microM) or pirenzepine (0.05-0.1 microM) blocked the CS- or eserine-facilitated release. 3. The protein kinase C (PKC) activator phorbol dibutyrate (PDB; 0.05 and 0.5 microM) increased the release of both [3H]NA and [14C]ACh in a concentration-dependent manner. Atropine blocked the PDB-induced facilitation of ACh release but not the facilitation of NA release. 4. The protein kinase A (PKA) activator 8-Br-cAMP did not affect ACh release but enhanced NA release. 5. The PKC inhibitor H-7 (50-100 microM) inhibited the CS- or eserine-facilitated release of both ACh and NA, but did not affect the non-facilitated release evoked by IS. H-7 also inhibited 0.5 microM PDB-induced facilitation of ACh release but not NA release. 6. Down-regulating PKC by pretreatment for 30 min with 5 microM PDB decreased the facilitated release of ACh and the eserine-induced facilitation of NA release. 7. Electrically evoked contractions of the bladder strips exhibited a biphasic response to PDB (2.5 microM), which consisted of an initial enhancement of the peak amplitude and area followed after 20 min by an inhibition of contractions. H-7 inhibited the electrically evoked contractions in a dose-dependent fashion. 8. It is concluded that a phospholipase C-PKC signal transduction pathway is essential for muscarinic receptor-induced facilitation of ACh and NA release but is not involved in the non-facilitated release of transmitters in the rat urinary bladder.
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PMID:M1 muscarinic receptor-induced facilitation of ACh and noradrenaline release in the rat bladder is mediated by protein kinase C. 891 Feb 12

Stimulation of HEL 299 cells with tumor necrosis factor alpha (TNF-alpha) or interleukin 1beta (IL-1beta) had no effect on M2 muscarinic receptor expression. However, the combination of these two cytokines markedly down-regulated muscarinic M2 receptor protein and mRNA expression and uncoupled M2 receptors from adenylyl cyclase. There was no effect of TNF-alpha and IL-1beta on the m2 muscarinic receptor mRNA stability, and nuclear run-on assays showed reduced m2 receptor gene transcription. Sequential cytokine addition suggests that the synergy involves postreceptor events. Although the cAMP-dependent protein kinase inhibitor H8 provided a significant protection against receptor down-regulation, the protein kinase C inhibitor GF109203X had no effect. The ceramide analog C2-ceramide (N-acetylsphingosine) was without effect on m2 receptor expression. However, a strong synergistic effect was demonstrated when cells were treated with the combination of C2-ceramide and TNF-alpha or IL-1beta. TNF-alpha and/or IL-1beta combination also activated the 46- and 55-kDa c-Jun NH2-terminal protein kinases and to a lesser extent p42 and p44 mitogen-activated protein kinase isoforms. Cycloheximide abolished the TNF-alpha and IL-1beta effect, suggesting that de novo protein synthesis is required for receptor down-regulation. These results suggest that the TNF-alpha and IL-1beta synergize to induce transcriptional down-regulation of the M2 muscarinic receptor, which seems to be mediated through activation of both ceramide and cAMP-dependent protein kinase pathways. Furthermore, these results suggest that M2 receptor expression is under the control of a cytokine network.
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PMID:Synergy between tumor necrosis factor alpha and interleukin 1beta in inducing transcriptional down-regulation of muscarinic M2 receptor gene expression. Involvement of protein kinase A and ceramide pathways. 895 85

Lovastatin, a cholesterol-lowering drug, has antiproliferative properties that may be related to its inhibition of protein isoprenylation. We examined the effects of lovastatin on signal transduction via the T-cell antigen receptor (TCR). Lovastatin inhibited both proximal and distal TCR-mediated signaling events in a time- and concentration-dependent manner in the human Jurkat T-cell line. Upregulation of CD69 surface expression after TCR stimulation was blocked by lovastatin, although no inhibition of phorbol ester-induced CD69 expression was noted. Proximal TCR-mediated signaling events, including intracellular calcium mobilization, inositol phosphate production, and tyrosine phosphorylation of phospholipase Cgamma1, were similarly inhibited by lovastatin, although global protein tyrosine kinase activity remained intact. In a Jurkat variant transfected with the human type-1 muscarinic receptor, lovastatin also inhibited TCR-mediated calcium mobilization and inositol phosphate production but failed to affect muscarinic receptor-induced responses. Lovastatin, at similar doses, also disrupted post-translational processing of ras and inhibited ras-dependent signals, including phosphorylation and activation of mitogen-associated protein kinase after TCR stimulation. These findings suggest that the antiproliferative properties of lovastatin may be independent of ras and could result from uncoupling protein tyrosine kinases from distinct signal transduction pathways.
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PMID:Lovastatin inhibits T-cell antigen receptor signaling independent of its effects on ras. 897 53

To determine if muscarinic receptor-activation plays a role in oligodendrocyte development, the effect of carbachol a stable acetylcholine analog, on gene expression and proliferation was investigated. Using Northern blot analysis we showed that carbachol caused a time and concentration-dependent increase in c-fos mRNA. This effect was blocked by atropine, a non-selective muscarinic antagonist. In addition, the muscarinic-stimulated c-fos increase was inhibited by 1-(5-isoquinoline-sulfonyl)-2-methylpiperazine (H-7), a potent inhibitor of protein kinase C (PKC), but not by N-2-(p-bromocinnamylamino)-ethyl-5-isoquinoline-sulfonamide (H-89), a potent inhibitor of protein kinase A, suggesting the involvement of PKC in mediating the response. Down-regulation of PKC by overnight pre-treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) blocked only the phorbol ester-stimulated c-fos accumulation while no effect was observed in the carbachol-induced response. These results suggested that carbachol stimulated an H-7 sensitive PKC pathway which may be different than that activated by TPA. Further evidence for two separate mechanisms of proto-oncogene induction was provided by the additive effect of carbachol and TPA. Induction of c-fos mRNA by carbachol was dependent on both influx of extracellular Ca2+ and release from intracellular stores, as both EDTA and BAPTA blocked the response. Since activation of muscarinic receptors can affect cell division in other cellular systems, the effect of carbachol on [3H]thymidine and bromodeoxyuridine incorporation into oligodendrocyte DNA was measured. Carbachol stimulated DNA synthesis in oligodendrocyte progenitors. This effect was mediated by muscarinic receptors as [3H]thymidine incorporation was prevented or significantly reduced by the addition of atropine. In conclusion, the present findings suggest that, the neurotransmitter, acetylcholine may act as a trophic factor in developing oligodendrocytes, regulating their growth and development in the central nervous system.
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PMID:Carbachol stimulates c-fos expression and proliferation in oligodendrocyte progenitors. 903 33

The molecular mechanisms involved in the regulation of muscarinic receptor gene expression are poorly understood. In an effort to gain a better understanding of the regulation of M2 receptors, we have investigated homologous and heterologous regulation of M2 muscarinic receptor protein and gene expression in human embryonic lung fibroblasts (HEL 299 cells). HEL 299 cells constitutively express m2 receptors, with no evidence of other muscarinic receptor subtypes. We have shown that M2 receptors in these cells can be down-regulated by muscarinic and beta2-adrenergic receptor agonists. Unlike the down-regulation mediated by muscarinic and beta-adrenergic stimulation, activation of PKC with PDBu was mediated through changes in m2 muscarinic receptor mRNA through reduced gene transcription. Because of the inflammatory nature of asthma, we have focused on delineating the interactions between cytokines and M2 receptors in an attempt to define potential endogenous modulators of M2 receptor expression. We have shown that the multi-functional cytokine, transforming growth factor beta1 (TGF-beta1), which is involved in several inflammatory conditions induces desensitization and down-regulation of M2 muscarinic receptor protein and gene expression that was mediated through a reduction in the rate of m2 receptor gene transcription. Other cytokines of interest are tumor necrosis factor alpha (TNF-alpha) and interleukin 1beta (IL-1beta) which are elevated in asthma. We have demonstrated that TNF-alpha and IL-1beta synergise to induce down-regulation of M2 muscarinic receptor protein and mRNA which was associated with functional desensitization of the receptor protein. The M2 receptor mRNA down-regulation appeared to be mediated through a reduction in the rate of m2 receptor gene transcription which may be dependent on the transcription and translation of unknown protein factor(s). Moreover, a role of PKA and ceramide pathways in M2 receptor regulation is suggested. Collectively, our work provides a mechanistic explanation of previous reports indicating altered function of M2 receptors in asthma. Ours results also suggest that the expression of this receptor subtype may be under the control of a cytokine network at the airways.
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PMID:Regulation of muscarinic M2 receptors. 912 42

The prostate gland from several animal species contains variable levels of muscarinic subtypes, but only the human prostate expresses significant levels of the m1 subtype. We studied muscarinic receptor activity in human benign prostatic hypertrophy (BPH) as well as several cell lines derived from prostate cancer. The BPH we studied expresses approximately 75% of the m1 receptor and undetectable levels of the other receptor subtypes whereas PC3 cells express only the m3 receptor subtype. DU145 and LnCaP cells express approximately equal levels of m1 and m3 receptor subtypes. Only the PC3 cells responded to carbachol with an increase in turnover of polyphosphoinositides, and none of the cell lines responded with effects on cAMP metabolism. Co-precipitation of receptors with heterotrimeric guanine nucleotide-binding regulatory proteins demonstrated interactions of the m1 receptors with Gi, Gq and G16 in BPH tissue and of the m1 and m3 receptors with Gi, Gq and G12 in PC3 and DU145 cells. Mitogen activated protein kinase (ERK) activity was seen in response to carbachol in PC3 and DU145 but not LnCaP cells. Finally, carbachol promoted cell proliferation in all three cell lines. Thus, there appears to be no consistent relationship between ERK activity, cell proliferation, and the subtype mediating the proliferative response, amongst these prostate cancer cell lines.
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PMID:Role of m1 receptor-G protein coupling in cell proliferation in the prostate. 912 62

The modulation of a constitutively active IRK1-like inwardly rectifying potassium channel, that is endogenously expressed in the RBL-2H3 cell, was studied with the whole-cell patch-clamp technique. Activation of G-proteins by intracellular application of GTP gamma S revealed a dual modulation of the inward rectifier. An initial increase in inward current amplitude was induced by GTP gamma S, followed by a profound inhibition of the current. The stimulation of the inward rectifier by GTP gamma S was abolished by pretreatment with pertussis toxin. The inhibitory phase of the GTP gamma S-induced response was pertussis toxin-insensitive. Stimulation of the m1-muscarinic receptor expressed in the RBL cell after stable transfection, induced an inhibition of the inwardly rectifying currents. Application of protein kinase C activators such as phorbol 12-myristate 13-acetate and phorbol 12,13-dibutyrate, resulted in a strong inhibition of the currents. Application of the cAMP-dependent protein kinase activator 8-bromo cAMP also induced an inhibition of the inward rectifier. It is concluded that the inward rectifier of the RBL-2H3 cell may be inhibited both by activation of protein kinase C and by cAMP-dependent protein kinase. As this type of inward rectifier is widely expressed in the nervous system, these data imply that the channel can be inhibited by receptors that stimulate phospholipase C and/or stimulate adenylyl cyclase, and can be activated by receptors that inhibit adenylyl cyclase activity.
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PMID:Dual modulation of an inwardly rectifying potassium conductance. 914 58

We have previously demonstrated that the phospholipase C-coupled m3-muscarinic receptor is phosphorylated in an agonist-sensitive manner by a protein kinase of approximately 40 kDa purified from porcine cerebellum (Tobin, A. B., Keys, B., and Nahorski, S. R. (1996) J. Biol Chem. 271, 3907-3916). This kinase, called muscarinic receptor kinase (MRK), is distinct from second messenger-regulated protein kinases and from beta-adrenergic receptor kinase and other members of the G-protein-coupled receptor kinase family. In the present study we propose that MRK is casein kinase 1alpha (CK1alpha) based on the following evidence: 1) the amino acid sequence from two proteolytic peptide fragments derived from purified MRK corresponded exactly to sequences within CK1alpha. 2) Casein kinase activity co-eluted with MRK activity from the final two chromatography steps in the purification of porcine brain MRK. 3) Recombinant CK1alpha expressed in Sf9 cells is able to phosphorylate both casein and the bacterial fusion protein, Ex-m3, that contains a portion of the third intracellular loop of the m3-muscarinic receptor downstream of glutathione S-transferase. 4) Partially purified CK1alpha increased the level of muscarinic receptor phosphorylation in an agonist-sensitive manner when reconstituted with membranes from Chinese hamster ovary-m3 cells expressing the human recombinant m3-muscarinic receptor. 5) Partially-purified CK1alpha phosphorylated rhodopsin, contained in urea-treated bovine rod outer segment membranes, and the extent of phosphorylation was increased in the presence of light. These data demonstrate that the kinase previously called MRK is CK1alpha, and that CK1alpha offers an alternative protein kinase pathway from that of the G-protein-coupled receptor kinase family for the stimulus-dependent phosphorylation of the m3-muscarinic receptor, rhodopsin, and possibly other G-protein-coupled receptors.
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PMID:Stimulus-dependent phosphorylation of G-protein-coupled receptors by casein kinase 1alpha. 925 10

Carbachol can stimulate insulin release in RINm5F cells by a mechanism that does not involve the elevation of cytosolic free Ca2+ concentrations or the activation of conventional protein kinase Cs (Mol Pharmacol 47:863-870, 1995). Thus, a novel signal transduction pathway links the muscarinic activation of the cells to increased insulin secretion. The question arises as to whether the pathway results from a novel receptor, different from the five established muscarinic receptors, or whether a "normal" receptor in the RINm5F cell activates a novel pathway. To distinguish between these two possibilities, the muscarinic receptors in the RINm5F cell were identified. Using polymerase chain reaction, combined with subcloning and DNA sequencing techniques, the cDNAs that encode the established M3 and M4 receptors were identified. The cDNAs for the Ml, M2, and M5 receptors were not found. Pharmacological studies showed a rank order of potency for muscarinic receptor subtype antagonists to inhibit carbachol-induced insulin release (half-maximal inhibitory concentration [pIC50] values given in parentheses): atropine (nonselective, 9.0) > 4-diphenyl-acetoxy-N-methyl piperidine methiodide (M3/M1, 8.6) > para-fluoro-hexahydrosiladiphenidol (M3, 8.1) > hexahydrosiladiphenidol (M3, 8.0) > tropicamide (M4, 6.4) > pirenzepine (M1, 6.1) > methoctramine (M2, 5.9). This antagonist profile suggests that it is the M3 receptor that mediates carbachol-induced insulin release. In this case, the novel signaling involved in the unusual carbachol response would not be due to a novel receptor but to the well-characterized M3 receptor. It appears, therefore, that the novel portion of the signaling pathway lies downstream of the M3 receptor and may consist of products of phosphatidylinositol hydrolysis, other than inositol triphosphate and diacylglycerol, resulting from the activation of phospholipase C. While a contributory role of the M4 receptor cannot be ruled out, there is no evidence in its favor other than its presence in the cell.
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PMID:Identification of muscarinic receptor subtypes in RINm5F cells by means of polymerase chain reaction, subcloning, and DNA sequencing. 928 41


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