Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tracheal cytotoxin (TCT) is a disaccharide-tetrapeptide released by Bordetella pertussis, the causative agent of pertussis (whooping cough). We have previously determined the structure of TCT to be GlcNAc-1,6-anhydro-MurNAc-L-Ala-gamma-D-Glu-meso-A2pm-D-Ala, where MurNAc = N-acetylmuramic acid and A2pm = diaminopimelic acid. Purified TCT reproduces the respiratory cytopathology observed during pertussis, including ciliostasis and extrusion of ciliated cells. We have tested structural analogs of TCT for their ability to reproduce native TCT toxicity in explanted hamster tracheal tissue and hamster trachea epithelial (HTE) cell cultures. Other investigators have evaluated many of these analogs, which are muramyl or desmuramyl peptides, for muramyl peptide activities such as immunopotentiation, induction of slow-wave sleep, and pyrogenicity. Four desmuramyl peptides were produced in our laboratory from B. pertussis peptidoglycan or by chemical synthesis, including unusual peptides containing alpha-aminopimelic acid in place of A2pm. Based on the relative ability of compounds to inhibit DNA synthesis in HTE cells, truncated analogs lacking A2pm entirely or lacking only the side-chain amine or carboxyl group of A2pm were less active than TCT by a factor of at least 1000. All active analogs included a native or near-native peptide moiety, independent of the presence, absence, or substitution of the sugar moiety. We conclude that the structural requirements for TCT toxicity differ considerably from those for most other muramyl peptide activities, in that the disaccharide moiety is irrelevant for toxicity and both the free amino and carboxyl groups of the A2pm side chain are required for activity.
 ...
PMID:Bordetella pertussis tracheal cytotoxin and other muramyl peptides: distinct structure-activity relationships for respiratory epithelial cytopathology. 846 Jan 47

The effects of the mu opioid receptor agonists, morphine and Tyr-D-Ala-Gly-N-methyl-Phe-Gly-ol (DAGO), the delta opioid receptor agonist, Tyr-D-Pen-Gly-Phe-D-penicillamine (DPDPE) and the kappa-opioid receptor agonist, dynorphin A-(1-13) on the whole-cell K+ currents (IK) of cultured mouse DRG neurons and neuroblastoma X DRG neuron hybrid F11 cells were studied. These opioid ligands all elicited dual effects. Low concentrations (< nM) usually elicited a transient increase in IK (within 1 min), followed by a sustained decrease in IK. In contrast, microM concentrations rapidly elicited a sustained increase in IK. After brief treatment with cholera toxin subunit B (CTX-B), the usual sustained decrease in IK evoked by < nM opioid agonists no longer occurred. Low concentrations then elicited only a sustained increase in IK. On the other hand, after chronic treatment with pertussis toxin (PTX), the usual microM opioid-induced increases in IK no longer occurred and more than half of the cells responded with a sustained decrease of IK to microM as well as nM opioids. The results suggest that mu, delta and kappa opioid receptors are each coupled to K+ channels through CTX-B- and PTX-sensitive transduction systems. Both systems have similar threshold concentrations to opioids. Activation of the CTX-B-sensitive opioid receptor/transduction system resulted in a decrease in K+ conductance of the cell which is generally associated with an increase in neuronal excitability. Activation of the other system resulted in an increase in K+ conductance which will, in general, decrease neuronal excitability. The net change in the IK depends upon which effect predominates. The dominance at different opioid concentrations may depend on the relative efficacies of the coupling of these two systems to K+ channels.
 ...
PMID:Dual regulation by mu, delta and kappa opioid receptor agonists of K+ conductance of DRG neurons and neuroblastoma X DRG neuron hybrid F11 cells. 857 91

A cDNA encoding the mouse delta opioid receptor was expressed stably in a Rat 1 fibroblast cell line. Expression of this receptor was demonstrated both in ligand binding studies and by reverse transcriptase-PCR. In membranes of clone D2 cells the opioid peptide [D-Ala(2)]-leucine enkephalin (DADLE) produced a robust, concentration-dependent, stimulation of basal high-affinity GTPase activity; the prototypic opioid antagonist naloxone and the highly selective and potent delta opioid ligands H-Tyr-Tic-Phe-Phe-OH (TIPP) and H-Tyr-Tic[Ch2-NH]Phe-Phe-OH (TIPP[psi]) had little effect but N,N-diallyl-Tyr-Aib-Aib-Phe-Leu (ICI174864) caused a marked dose-dependent inhibition of this activity (Tic, 1,2,3,4-tetrahydroisoquinolin-2-yl-carbonyl]; Aib, alpha-aminobutyric acid). This effect of ICI174864 was reversed by TIPP[psi] and attenuated after treatment of the cells with pertussis toxin. No stimulation by DADLE or inhibition by ICI174864 was observed in Rat 1 fibroblasts that did not express the delta opioid receptor. Basal binding of [(35)S]guanosine 5'-O-(3-thio-triphosphate) to membranes of clone D2 cells was also stimulated by DADLE and inhibited by ICI174864; both of these effects were reversed by co-incubation with TIPP[psi]. When cholera toxin-catalysed [(32)P]ADP-ribosylation was performed on membranes of clone D2 cells in the absence of guanine nucleotides, a 40 kDa G1-family polypeptide was labelled in addition to both the long and short isoforms of Gsalpha. Labelling of the 40 kDa polypeptide was enhanced by addition of DADLE and fully attenuated by addition of ICI174864. In contrast, labelling of the isoforms of Gsalpha was unaffected by either opioid ligand. Again, both the positive effect of DADLE and the inhibitory effect of ICI174864 were prevented by co-incubation with TIPP[psi] which, in isolation, had little effect on cholera toxin-catalysed [(32)P]ADP-ribosylation of either Gs or Gi. These data demonstrate that the delta opioid receptor displays a spontaneous activity when expressed in this genetic background. Attenuation of this activity is produced by ICI174864, which by acting as an 'inverse agonist' in this system, functionally uncouples the expressed receptor from the cellular G-protein population. The complete attenuation of agonist-independent cholera toxin-catalysed [(32)P]ADP-ribosylation of Gi demonstrated that ICI174864 acts as an inverse agonist with high intrinsic activity at this receptor.
 ...
PMID:Analysis of inverse agonism at the delta opioid receptor after expression in Rat 1 fibroblasts. 867 Jan 11

1. In this study we have investigated delta and mu opioid receptor-mediated elevation of intracellular Ca2+ concentration ([Ca2+]i) in the human neuroblastoma cell line, SH-SY5Y. 2. The Ca(2+)-sensitive dye, fura-2, was used to measure [Ca2+]i in confluent monolayers of SH-SY5Y cells. Neither the delta-opioid agonist, DPDPE ([D-Pen2,5]-enkephalin) nor the mu-opioid agonist, DAMGO (Tyr-D-Ala-Gly-N-Me-Phe-Gly-ol enkephalin) elevated [Ca2+]i when applied alone. However, when either DPDPE or DAMGO was applied in the presence of the cholinoceptor agonist, carbachol (100 nM-1 mM) they evoked an elevation of [Ca2+]i above that caused by carbachol alone. 3. In the presence of 1 microM or 100 microM carbachol, DPDPE elevated [Ca2+]i with an EC50 of 10 nM. The elevation of [Ca2+]i was independent of the concentration of carbachol. The EC50 for DAMGO elevating [Ca2+]i in the presence of 1 microM and 100 microM carbachol was 270 nM and 145 nM respectively. 4. The delta-receptor antagonist, naltrindole (30 nM), blocked the elevations of [Ca2+]i by DPDPE (100 nM) without affecting those caused by DAMGO while the mu-receptor antagonist, CTAP (D-Phe-Cys-Tyr-D-Trp-Arg-Pen-Thr-NH2) (100 nM-1 microM) blocked the elevations of [Ca2+]i caused by DAMGO (1 microM) without affecting those caused by DPDPE. 5. Block of carbachol activation of muscarinic receptors with atropine (10 microM) abolished the elevation of [Ca2+]i by the opioids. The nicotinic receptor antagonist, mecamylamine (10 microM), did not affect the elevations of [Ca2+]i caused by opioids in the presence of carbachol. 6. Muscarinic receptor activation, not a rise in [Ca2+]i, was required to reveal the opioid response. The Ca2+ channel activator, maitotoxin (3 ng ml-1), also elevated [Ca2+]i but subsequent application of opioid in the presence of maitotoxin caused no further changes in [Ca2+]i. 7. The elevations of [Ca2+]i by DPDPE and DAMGO were abolished by pretreatment of the cells with pertussis toxin (200 ng ml-1, 16 h). This treatment did not significantly affect the response of the cells to carbachol. 8. The opioids appeared to elevate [Ca2+]i by mobilizing Ca2+ from intracellular stores. Both DPDPE and DAMGO continued to elevate [Ca2+]i when applied in nominally Ca(2+)-free external buffer or when applied in a buffer containing a cocktail of Ca2+ entry inhibitors. Thapsigargin (100 nM), an agent which discharges intracellular Ca2+ stores, also blocked the opioid elevations of [Ca2+]i. 9. delta and mu Opioids did not appear to mobilize intracellular Ca2+ by modulating the activity of protein kinases. The application of H-89 (10 microM), an inhibitor of protein kinase A, H-7 (100 microM), an inhibitor of protein kinase C, protein kinase A and cyclic GMP-dependent protein kinase, or Bis I, an inhibitor of protein kinase C, did not alter the opioid mobilization of [Ca2+]i. 10. Thus, in SH-SY5Y cells, opioids can mobilize Ca2+ from intracellular stores but they require ongoing muscarinic receptor activation. Opioids do not elevate [Ca2+]i when applied alone.
 ...
PMID:delta- and mu-opioid receptor mobilization of intracellular calcium in SH-SY5Y human neuroblastoma cells. 878 87

In C6 glioma cells stably expressing a homogeneous population of the cloned rat mu opioid receptor, the binding affinities of opioid agonists and subsequent activation of G protein were examined. Opioid receptor number in membranes of these cells was high (10-30 pmol/mg protein [3H]diprenorphine binding sites). Opioids were found to bind to the receptor with high affinity [Tyr-D-Ala-Gly-(Me)Phe-Gly-ol (DAMGO) 0.23 nM; sufentanil 0.034 nM; morphine 0.16 nM]. Activation of G protein by opioid agonists was examined by measuring the stimulation of guanosine-5'-O-(3-[35S]thio)triphosphate ([35S]GTP gamma S) binding. Sufentanil increased [35S]GTP gamma S binding by 326% with an EC50 value of 2.39 nM. Agonist stimulation of [35S]GTP gamma S binding was stereoselective, naltrexone-reversible, and pertussis toxin-sensitive. The "intrinsic activity" of opioids at the mu receptor was reflected by the magnitude of agonist-mediated activation of G protein. The rank order of the stimulation of [35S]GTP gamma S binding was etonitazene = sufentanil = DAMGO = PLO17 = fentanyl > morphine > profadol > meperidine > butorphanol = nalbuphine = pentazocine > cyclazocine = nalorphine > levallorphan > naltrexone. High affinity binding of ligands to the mu opioid receptor was reduced by the addition of sodium and guanosine diphosphate at concentrations used in the [35S]GTP gamma S binding assay. Ligand affinity was reduced in a manner correlating with "intrinsic activity". DAMGO, 1229-fold, nalbuphine 35-fold, naltrexone, 3-fold. The results presented show that the stable expression of the rat mu opioid receptor in C6 cells provides an effective tool to examine opioid receptor signal transduction mechanisms and evaluate the activity of novel opioids at the mu receptor.
 ...
PMID:Characterization of opioid agonist efficacy in a C6 glioma cell line expressing the mu opioid receptor. 881 94

Microglia are important immune effector cells within the brain. The phagocytosis of nonopsonized Cryptococcus neoformans by swine microglia was used as an in vitro model for studies on cellular mechanisms of opiate-mediated immunomodulation in the brain. Morphine inhibited potently (IC50 approximately 10(-16) M) the phagocytosis of C. neoformans by primary cultures of neonatal pig microglia. The mu opioid agonist Tyr-D-Ala-Gly-N-Me-Phe-Gly-ol (DAMGO) also suppressed phagocytosis but with a much lower potency than morphine (IC50 approximately 10(-8) M). The inhibitory effects of morphine and DAMGO were blocked by equimolar concentrations of naloxone and by the selective mu opiate receptor antagonist beta-funaltrexamine. Pertussis toxin but not cholera toxin reversed the inhibitory effects of both morphine and DAMGO. Our data suggest that morphine inhibits phagocytosis of C. neoformans by swine microglia via a mechanism involving mu opiate receptors coupled to a pertussis toxin-sensitive Gi/G(o) protein signaling pathway.
 ...
PMID:Inhibition of swine microglial cell phagocytosis of Cryptococcus neoformans by femtomolar concentrations of morphine. 911 3

Whole-cell patch-clamp recordings were used to study Ba2+ currents through voltage-dependent Ca2+ channels in dorsal root ganglion x mouse neuroblastoma hybrid (F-11) cells. Opioid agonists selective for either mu (Tyr-D-Ala-Gly-Mephe-Gly-ol; DAMGO) or delta (Tyr-D-Pen-Gly-Phe-D-Pen-OH; DPDPE) receptors inhibited high-threshold Ba2+ currents. The inhibition was reversible, naloxone-sensitive, and dose-dependent. The inhibitory effects of both DAMGO and DPDPE were blocked by pretreatment of the cells with pertussis toxin (PTX) as well as by brief exposure to the sulfhydryl alkylating agent, N-ethylmaleimide (NEM). The N-type Ca2+ channel antagonist omega-conotoxin GVIA (omega-CTX GVIA) irreversibly inhibited high threshold Ba2+ currents by 66% and blocked the inhibitory effect of DAMGO or DPDPE. In contrast, the L-type Ca2+ channel blocker nifedipine inhibited high threshold Ba2+ currents by 15% and failed to block the inhibitory effect of DAMGO or DPDPE. These results demonstrate that mu and delta opioid receptors are negatively coupled to N-type Ca2+ channels via PTX- and NEM-sensitive GTP-binding proteins in F-11 cells.
 ...
PMID:Mu and delta opioids but not kappa opioid inhibit voltage-activated Ba2+ currents in neuronal F-11 cell. 935 88

The mu opioid receptor (MOR) has been shown to desensitize after 1 h of exposure to the opioid peptide, [D-Ala(2), N-MePhe(4), Gly-ol(5)]enkephalin (DAMGO), largely by the loss of receptors from the cell surface and receptor down-regulation. We have previously shown that the Thr(394) in the carboxyl tail is essential for agonist-induced early desensitization, presumably by serving as a primary phosphorylation site for G protein-coupled receptor kinase. Using a T394A mutant receptor, we determined that Thr(394) was also responsible for mu opioid receptor down-regulation. The T394A mutant receptor displayed 50% reduction of receptor down-regulation (14.8%) compared with wild type receptor (34%) upon 1 h of exposure to DAMGO. Agonist-induced T394A receptor down-regulation was unaffected by pertussis toxin treatment, indicating involvement of a mechanism independent of G protein function. Interestingly, pertussis toxin-insensitive T394A receptor down-regulation was completely inhibited by a tyrosine kinase inhibitor, genistein. Tyrosine kinase inhibition blocked wild type MOR down-regulation by 50%, and the genistein-resistant wild type MOR down-regulation was completely pertussis toxin-sensitive. Following DAMGO stimulation, MOR was shown to be phosphorylated at tyrosine residue(s), indicating that the receptor was a direct substrate for tyrosine kinase action. Mutagenesis of the four intracellular tyrosine residues resulted in complete inhibition of the G protein-insensitive MOR internalization. Therefore, agonist-induced MOR down-regulation appears to be mediated by two distinct cellular signal transduction pathways. One is G protein-dependent and GRK-dependent, which can be abolished by pertussis toxin treatment of wild type MOR or by mutagenesis of Thr(394). The other novel pathway is G protein-independent but tyrosine kinase-dependent, blocked by genistein treatment, and one in which Thr(394) has no regulatory role but phosphorylation of tyrosine residues appears essential.
 ...
PMID:Agonist-induced, G protein-dependent and -independent down-regulation of the mu opioid receptor. The receptor is a direct substrate for protein-tyrosine kinase. 1048

Activation of delta-opioid receptors in NG108-15 cells releases Ca2+ from an intracellular store through activation of a pertussis toxin-sensitive G protein. We tested the hypothesis that activation of delta-opioid receptors mobilizes inositol 1,4,5-trisphosphate (IP(3))-sensitive Ca2+ stores via liberation of Gbetagamma. Fura-2-based digital imaging was used to study the mechanism of opioid-induced increases in [Ca2+](i) in NG108-15 cells. Exposure to D-Ala(2)-D-Leu(5) enkephalin (100 nM) for 90 s induced increases in [Ca2+](i) that were blocked by microinjection of the IP(3) receptor antagonist heparin (pipette concentration = 100 mg/ml) but not by sham injection. Microinjection of a peptide that binds Gbetagamma (QEHA, 1 mM) decreased the D-Ala(2)-D-Leu(5) enkephalin-evoked response. Microinjection of an inactive peptide (SKEE, 1 mM) that does not bind to Gbetagamma failed to inhibit the opioid-induced increase in [Ca2+](i). Microinjection of a peptide (QLKK, 15 mM) that binds to free Galpha(q) blocked the increase evoked by 3 nM bradykinin, but microinjection of an inactive peptide (ADRK, 15 mM) did not. Microinjection of QLKK did not significantly affect the opioid-induced increase in [Ca2+](i). Collectively, these data demonstrate that activation of delta-opioid receptors induces the release of Ca2+ from IP(3)-sensitive stores in NG108-15 cells through activation of the betagamma subunits of inhibitory G proteins.
 ...
PMID:Delta-opioid-induced liberation of Gbetagamma mobilizes Ca2+ stores in NG108-15 cells. 1053 93

Nociceptin, an endogenous agonist of the opioid receptor-like(1) (ORL(1)) receptor, is implicated in a wide range of physiological functions including cardiovascular control. However, the effect of nociceptin on peripheral sympathetic ganglion neurons has not been studied. Whole-cell voltage clamp was used to study Ca(2+) currents on freshly dissociated sympathetic superior cervical ganglion neurons from juvenile rats. Nociceptin (1 microM) caused a fast inhibition of the peak currents by 69+/-3% in all neurons. Strong positive prepulses counteracted the inhibition of the peak current by 64% and no effect of nociceptin was observed when the cells were pre-incubated with Pertussis toxin. The inhibition was reversible and dose-dependent with an EC(50) of 508+/-50 pM. Blockade of N-type channels by 1 microM omega-conotoxin GVIA reduced the peak currents by 83+/-1% and abolished the action of nociceptin. Naloxone could not prevent the inhibition by nociceptin and [D-Ala(2), N-Me-Phe(4), Gly(5)-ol] enkephalin (DAMGO) only depressed a small proportion of the current in 1/7 neurons. These data suggests that nociceptin inhibits transmitter release from sympathetic neurons by a selective blockade of N-type channels, which may be of importance for its depressive effect on the cardiovascular system.
 ...
PMID:Nociceptin is a potent inhibitor of N-type Ca(2+) channels in rat sympathetic ganglion neurons. 1110 96


<< Previous 1 2 3 4 Next >>