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)

We have recently identified a peptide derived from the secreted portion of the HSV-2 glycoprotein G, gG-2p20, to be proinflammatory. Based on its ability to activate neutrophils and monocytes via the formyl peptide receptor (FPR) to produce reactive oxygen species (ROS) that down-regulate NK cell function, we suggested it to be of importance in HSV-2 pathogenesis. We now describe the effects of an overlapping peptide, gG-2p19, derived from the same HSV-2 protein. Also, this peptide activated the ROS-generating NADPH-oxidase, however, only in monocytes and not in neutrophils. Surprisingly, gG-2p19 did not induce a chemotactic response in the affected monocytes despite using a pertussis toxin-sensitive, supposedly G-protein-coupled receptor. The specificity for monocytes suggested that FPR and its homologue FPR like-1 (FPRL1) did not function as receptors for gG-2p19, and this was also experimentally confirmed. Surprisingly, the monocyte-specific FPR homologue FPRL2 was not involved either, and the responsible receptor thus remains unknown so far. However, the receptor shares some basic signaling properties with FPRL1 in that the gG-2p19-induced response was inhibited by PBP10, a peptide that has earlier been shown to selectively inhibit FPRL1-triggered responses. We conclude that secretion and subsequent degradation of the HSV-2 glycoprotein G can generate several peptides that activate phagocytes through different receptors, and with different cellular specificities, to generate ROS with immunomodulatory properties.
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PMID:A monocyte-specific peptide from herpes simplex virus type 2 glycoprotein G activates the NADPH-oxidase but not chemotaxis through a G-protein-coupled receptor distinct from the members of the formyl peptide receptor family. 1794 82

The pathogenesis of nonalcoholic steatohepatitis (NASH) is unclear, despite epidemiological data implicating FFAs. We studied the pathogenesis of NASH using lipoapoptosis models. Palmitic acid (PA) induced classical apoptosis of hepatocytes. PA-induced lipoapoptosis was inhibited by acyl-CoA synthetase inhibitor but not by ceramide synthesis inhibitors, suggesting that conversion products other than ceramide are involved. Phospholipase A(2) (PLA(2)) inhibitors blocked PA-induced hepatocyte death, suggesting an important role for PLA(2) and its product lysophosphatidylcholine (LPC). Small interfering RNA for Ca(2+)-independent phospholipase A(2) (iPLA(2)) inhibited the lipoapoptosis of hepatocytes. PA increased LPC content, which was reversed by iPLA(2) inhibitors. Pertussis toxin or dominant-negative Galpha(i) mutant inhibited hepatocyte death by PA or LPC acting through G-protein-coupled receptor (GPCR)/Galpha(i). PA decreased cardiolipin content and induced mitochondrial potential loss and cytochrome c translocation. Oleic acid inhibited PA-induced hepatocyte death by diverting PA to triglyceride and decreasing LPC content, suggesting that FFAs lead to steatosis or lipoapoptosis according to the abundance of saturated/unsaturated FFAs. LPC administration induced hepatitis in vivo. LPC content was increased in the liver specimens from NASH patients. These results demonstrate that LPC is a death effector in the lipoapoptosis of hepatocytes and suggest potential therapeutic values of PLA(2) inhibitors or GPCR/Galpha(i) inhibitors in NASH.
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PMID:Lysophosphatidylcholine as a death effector in the lipoapoptosis of hepatocytes. 1795 Dec 22

Native LDL may be a mitogenic stimulus of VSMC proliferation in lesions where endothelial disruption occurs. Recent studies have demonstrated that the mitogenic effects of LDL are accompanied by Erk1/2 activation via an unknown G-protein-coupled receptor (GPCR). In this article, we report that LDL translocated PKCbeta(II) and PKCtheta from cytosol to plasma membrane, and inhibition of PKCbeta(II) and PKCtheta decreased LDL effects via the deactivation of Erk1/2. Moreover, pertussis toxin, but not cholera toxin or heparin, inhibited LDL-induced translocation of PKCbeta(II) and PKCtheta, suggesting that Gi protein plays a role in LDL effects. Of LPA, S1P, and LDL, whose signaling is conveyed via Gi/o proteins, only LDL induced translocation of PKCbeta(II) and PKCtheta. Inhibition of PKCbeta(II) or PKCtheta, as well as of Erk1/2 and GPCR, decreases LDL-induced upregulation of Egr-1, which is critical for cell proliferation. This is the first report, to our knowledge, that the participation of PKCtheta in VSMC proliferation is unique.
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PMID:Activation of PKCbeta(II) and PKCtheta is essential for LDL-induced cell proliferation of human aortic smooth muscle cells via Gi-mediated Erk1/2 activation and Egr-1 upregulation. 1821 22

Kisspeptins are a family of peptides encoded by the KISS1 gene, which binds to G-protein-coupled receptor (GPR54), an orphan GPR54 related to galanin receptors. Endogenous forms composed of 54, 14, and 13 amino acids have been identified. Kisspeptin and GPR54 mRNAs have been detected in pancreatic B and A cells. Furthermore, kisspeptin-54 has been shown to slightly stimulate the last phase of glucose-induced insulin secretion in mouse and human islets and to inhibit insulin release in MIN6 cells. We have investigated the effect of kisspeptin-13 on insulin, glucagon, and somatostatin secretion. The study was performed in the perfused rat pancreas. Glucose, arginine, carbachol, and exendin-4 were used as secretagogues. Hormones were measured by RIA. Kisspeptin-13 reduced glucose-induced insulin secretion in a dose-dependent manner (IC(50)=1.2 nM) and inhibited the insulin responses to both carbachol and exendin-4. Kisspeptin-13 blocked arginine-induced insulin secretion without affecting the glucagon or somatostatin responses to this amino acid, thus indicating that kisspeptin-13 influences B cells directly, rather than through an A- or D-cell paracrine effect. The reduction of the insulin response to exendin-4 induced by kisspeptin-13 was also observed in pertussis toxin-treated rats, thus suggesting an inhibition independent of G(i) proteins. In view of the potent insulinostatic effect of kisspeptin-13, it is tempting to speculate that kisspeptins may be implicated in the regulation of B-cell secretion.
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PMID:Kisspeptin-13 inhibits insulin secretion without affecting glucagon or somatostatin release: study in the perfused rat pancreas. 1825 51

Extracellular signal-regulated kinases (ERKs) play important physiological roles in proliferation, differentiation and gene expression. ERK5 is twice the size of ERK1/2, the amino-terminal half contains the kinase domain that shares the homology with ERK1/2 and TEY activation motif, whereas the carboxy-terminal half is unique. In this study, we examined the cross-talk mechanism between G-protein-coupled receptors (GPCRs) and receptor tyrosine kinases, focusing on ERK1/2 and 5. The pretreatment of rat pheochromocytoma cells (PC12) with pertussis toxin (PTX) specifically enhanced epidermal growth factor (EGF)-induced ERK5 phosphorylation. In addition, lysophosphatidic acid (LPA) attenuated the EGF-induced ERK5 phosphorylation in LPA(1) receptor- and G(i/o)-dependent manners. On the other hand, LPA alone activated ERK1/2 via Gbetagamma subunits and Ras and potentiated EGF-induced ERK1/2 phosphorylation at late time points. These results suggest G(i/o) negatively regulates ERK5, while it positively regulates ERK1/2. LPA did not affect cAMP levels after EGF treatment, and the reagents promoting cAMP production such as forskolin and cholera toxin also attenuated the EGF-induced ERK5 phosphorylation, indicating that the inhibitory effect of LPA on ERK5 inhibition via G(i/o) is not due to inhibition of adenylyl cyclase by Galpha(i/o). However, the inhibitory effect of LPA on ERK5 was abolished in PC12 cells stably overexpressing C-terminus of GPCR kinase2 (GRK2), and overexpression of Gbeta(1) and gamma(2) subunits also suppressed ERK5 phosphorylation by EGF. In response to LPA, Gbetagamma subunits interacted with EGF receptor in a time-dependent manner. These results strongly suggest that LPA negatively regulates the EGF-induced ERK5 phosphorylation through Gbetagamma subunits.
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PMID:Betagamma subunits of G(i/o) suppress EGF-induced ERK5 phosphorylation, whereas ERK1/2 phosphorylation is enhanced. 1840 64

The opioid receptor-like 1 (NOP or ORL1) receptor is a G-protein-coupled receptor the endogenous ligand of which is the heptadecapeptide, nociceptin (Noc). NOP receptors are known to modulate pain processing at spinal, supraspinal, and peripheral levels. Previous work has demonstrated that NOP receptors inhibit N-type Ca2+ channel currents in rat sympathetic stellate ganglion (SG) neurons via pertussis toxin (PTX)-sensitive Galphai/o subunits. However, the identification of the specific Galpha subunit that mediates the Ca2+ current modulation is unknown. The purpose of the present study was to examine coupling specificity of Noc-activated NOP receptors to N-type Ca2+ channels in SG neurons. Small interference RNA (siRNA) transfection was employed to block the expression of PTX-sensitive Galpha subunits. RT-PCR results showed that siRNA specifically decreased the expression of the intended Galpha subunit. Evaluation of cell surface protein expression and Ca2+ channel modulation were assessed by immunofluorescence staining and electrophysiological recordings, respectively. Furthermore, the presence of mRNA of the intended siRNA target Galpha protein was examined by RT-PCR experiments. Fluorescence imaging showed that Galphai1, Galphai3, and Galphao were expressed in SG neurons. The transfection of Galphai1-specific siRNA resulted in a significant decrease in Noc-mediated Ca2+ current inhibition, while silencing of either Galphai3 or Galphao was without effect. Taken together, these results suggest that in SG neurons Galphai1 subunits selectively couple NOP receptors to N-type Ca2+ channels.
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PMID:Coupling specificity of NOP opioid receptors to pertussis-toxin-sensitive Galpha proteins in adult rat stellate ganglion neurons using small interference RNA. 1856 51

The extracellular calcium-sensing receptor (CaSR), a seven transmembrane G-protein-coupled receptor, was cloned in 1993. Its activation was first associated to the regulation of calcium homeostasis; however, the presence in tissues unrelated with this role has revealed its participation in numerous other cell functions. We previously described CaSR expression in human adipocytes, and here we investigated the effect of its activation on adipocyte lipolytic activity by measuring glycerol release to the incubation medium. Treatment of adipocytes with CaSR agonists elicited an inhibitory effect on basal lipolysis, which was prevented by a CaSR antagonist. To further corroborate the antilipolytic effect of CaSR activation, lipolysis was evaluated under conditions that interfere with main antilipolytic regulatory pathways. Cells were preincubated with pertussis toxin (PT, a Gialpha protein inhibitor), the phosphatidylinositol 3 kinase (PI3K) inhibitors wortmannin and LY-294002 as well as the cAMP analog 8Br-cAMP, all of which influenced the antilipolytic effect of CaSR stimulation. In light of the current view of adipose tissue as an organ involved in whole-body metabolic control, the role of the CaSR modulating basal lipolysis elicits great interest, given its metabolic sensing capabilities due to the variety of ligands that regulate its activity, and its potential cross-talk with insulin and adipose tissue-secreted factors.
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PMID:Antilipolytic effect of calcium-sensing receptor in human adipocytes. 1862 38

alpha-Conotoxins Vc1.1 and Rg1A are peptides from the venom of marine Conus snails that are currently in development as a treatment for neuropathic pain. Here we report that the alpha9alpha10 nicotinic acetylcholine receptor-selective conotoxins Vc1.1 and Rg1A potently and selectively inhibit high-voltage-activated (HVA) calcium channel currents in dissociated DRG neurons in a concentration-dependent manner. The post-translationally modified peptides vc1a and [P6O]Vc1.1 were inactive, as were all other alpha-conotoxins tested. Vc1.1 inhibited the omega-conotoxin-sensitive HVA currents in DRG neurons but not those recorded from Xenopus oocytes expressing Ca(V)2.2, Ca(V)2.1, Ca(V)2.3, or Ca(V)1.2 channels. Inhibition of HVA currents by Vc1.1 was not reversed by depolarizing prepulses but was abolished by pertussis toxin (PTX), intracellular GDPbetaS, or a selective inhibitor of pp60c-src tyrosine kinase. These data indicate that Vc1.1 does not interact with N-type calcium channels directly but inhibits them via a voltage-independent mechanism involving a PTX-sensitive, G-protein-coupled receptor. Preincubation with a variety of selective receptor antagonists demonstrated that only the GABA(B) receptor antagonists, [S-(R*,R*)][-3-[[1-(3,4-dichlorophenyl)ethyl]amino]-2-hydroxy propyl]([3,4]-cyclohexylmethyl) phosphinic acid hydrochloride (2S)-3[[(1S)-1-(3,4-dichlorophenyl)-ethyl]amino-2-hydroxypropyl](phenylmethyl) phosphinic acid and phaclofen, blocked the effect of Vc1.1 and Rg1A on Ca2+ channel currents. Together, the results identify Ca(V)2.2 as a target of Vc1.1 and Rg1A, potentially mediating their analgesic actions. We propose a novel mechanism by which alpha-conotoxins Vc1.1 and Rg1A modulate native N-type (Ca(V)2.2) Ca2+ channel currents, namely acting as agonists via G-protein-coupled GABA(B) receptors.
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PMID:Analgesic alpha-conotoxins Vc1.1 and Rg1A inhibit N-type calcium channels in rat sensory neurons via GABAB receptor activation. 1894 2

beta-Arrestin recruitment assays provide a generic assay platform for drug discovery on G-protein-coupled receptors (GPCRs). The PathHunter assay technology developed by DiscoveRx (Fremont, CA) uses enzyme fragment complementation of beta-galactosidase to measure receptor-beta-arrestin proximity by chemiluminescence. This study describes an agonistic screen on the human endothelial differentiation sphingolipid GPCR 1 (EDG1), also known as S1P1, using PathHunter beta-arrestin recruitment technology. Screening of a collection of 345,052 compounds yielded 2157 agonistic hits. Only 10 of these compounds showed beta-arrestin recruitment activity on a nonrelated receptor, indicating high accuracy and specificity of the assay. The authors show that receptor activation with reference agonists can be detected within the same EDG1 PathHunter cell line at the level of beta-arrestin recruitment, G(i/o) protein-mediated inhibition of cyclic adenosine monophosphate (cAMP), and activation of downstream phosphorylation of extracellular signal-regulated protein kinases. The degree of beta-arrestin recruitment was largely unaffected upon blockade of G(i/o) protein signaling with pertussis toxin, whereas kinetic studies demonstrated a lower rate of beta-arrestin-receptor association. In contrast, inhibition of cAMP and phosphorylation of extracellular signal-regulated protein kinases were fully G(i/o) protein regulated. The data indicate that the beta-arrestin enzyme fragment complementation cell line can be used not only for agonistic screening of GPCRs but also for the identification of "biased ligands" (i.e., compounds that differ in G-protein coupling and beta-arrestin-mediated cellular effects).
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PMID:beta-Arrestin recruitment assay for the identification of agonists of the sphingosine 1-phosphate receptor EDG1. 1903 7

Regulation of cellular metabolism by the citric acid cycle occurs in the mitochondria. However, the citric acid cycle intermediate succinate was shown recently to be a ligand for the G-protein-coupled receptor GPR91. Here, we describe a role for succinate and its receptor in the stimulation of hematopoietic progenitor cell (HPC) growth. GPR91 mRNA and protein expression were detected in human bone marrow CD34+ progenitor cells, as well as in erythroid and megakaryocyte cultures and the erythroleukemic cell line TF-1. Treatment of these cell cultures with succinate resulted in increased proliferation rates. The proliferation response of TF-1 cells was pertussis toxin (PTX)-sensitive, suggesting a role for Gi signaling. Proliferation was also blocked when TF-1 cells were transfected with small interfering RNA specific for GPR91. Succinate stimulated activation of the Erk MAPK pathway and inositol phosphate accumulation in a PTX-sensitive manner. Pretreatment of TF-1 cells with the Erk1/2 kinase (MEK) inhibitor PD98059 blocked the proliferation response. Succinate treatment additionally protected TF-1 cells from cell death induced by serum deprivation. Finally, in vivo administration of succinate was found to elevate the levels of hemoglobin, platelets, and neutrophils in a mouse model of chemotherapy-induced myelosuppression. These results suggest that succinate-GPR91 signaling is capable of promoting HPC development.
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PMID:The role of the GPR91 ligand succinate in hematopoiesis. 1920 47


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