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Sample records for p2x7 receptors mediate

  1. P2X7 receptors in satellite glial cells mediate high functional expression of P2X3 receptors in immature dorsal root ganglion neurons

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    Chen Yong

    2012-02-01

    Full Text Available Abstract Background The purinergic P2X3 receptor (P2X3R expressed in the dorsal root ganglion (DRG sensory neuron and the P2X7 receptor (P2X7R expressed in the surrounding satellite glial cell (SGC are two major receptors participating in neuron-SGC communication in adult DRGs. Activation of P2X7Rs was found to tonically reduce the expression of P2X3Rs in DRGs, thus inhibiting the abnormal pain behaviors in adult rats. P2X receptors are also actively involved in sensory signaling in developing rodents. However, very little is known about the developmental change of P2X7Rs in DRGs and the interaction between P2X7Rs and P2X3Rs in those animals. We therefore examined the expression of P2X3Rs and P2X7Rs in postnatal rats and determined if P2X7R-P2X3R control exists in developing rats. Findings We immunostained DRGs of immature rats and found that P2X3Rs were expressed only in neurons and P2X7Rs were expressed only in SGCs. Western blot analyses indicated that P2X3R expression decreased while P2X7R expression increased with the age of rats. Electrophysiological studies showed that the number of DRG neurons responding to the stimulation of the P2XR agonist, α,β-meATP, was higher and the amplitudes of α,β-meATP-induced depolarizations were larger in immature DRG neurons. As a result, P2X3R-mediated flinching responses were much more pronounced in immature rats than those found in adult rats. When we reduced P2X7R expression with P2X7R-siRNA in postnatal and adult rats, P2X3R-mediated flinch responses were greatly enhanced in both rat populations. Conclusions These results show that the P2X7R expression increases as rats age. In addition, P2X7Rs in SGCs exert inhibitory control on the P2X3R expression and function in sensory neurons of immature rats, just as observed in adult rats. Regulation of P2X7R expression is likely an effective way to control P2X3R activity and manage pain relief in infants.

  2. P2X7 Receptor Function in Bone-Related Cancer

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    Elena Adinolfi

    2012-01-01

    Full Text Available Modulation of tumor microenvironment by different mediators is central in determining neoplastic formation and progression. Among these molecules extracellular ATP is emerging as a good candidate in promoting cell growth, neovascularization, tumor-host interactions, and metastatization. This paper summarizes recent findings on expression and function of P2X7 receptor for extracellular ATP in primary and metastatic bone cancers. Search of mRNA expression microchip databases and literature analysis demonstrate a high expression of P2X7 in primary bone tumors as well as in other malignancies such as multiple myeloma, neuroblastoma, breast, and prostate cancer. Evidence that P2X7 triggers NFATc1, PI3K/Akt, ROCK, and VEGF pathways in osteoblasts promoting either primary tumor development or osteoblastic lesions is also reported. Moreover, P2X7 receptor is involved in osteoclast differentiation, RANKL expression, matrix metalloproteases and cathepsin secretion thus promoting bone resorption and osteolytic lesions. Taken together these data point to a pivotal role for the P2X7 receptor in bone cancer biology.

  3. The scavenger activity of the human P2X7 receptor differs from P2X7 pore function by insensitivity to antagonists, genetic variation and sodium concentration: Relevance to inflammatory brain diseases.

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    Ou, Amber; Gu, Ben J; Wiley, James S

    2018-04-01

    Activation of P2X7 receptors is widely recognised to initiate proinflammatory responses. However P2X7 also has a dual function as a scavenger receptor which is active in the absence of ATP and plasma proteins and may be important in central nervous system (CNS) diseases. Here, we investigated both P2X7 pore formation and its phagocytic function in fresh human monocytes (as a model of microglia) by measuring ATP-induced ethidium dye uptake and fluorescent bead uptake respectively. This was studied in monocytes expressing various polymorphic variants as well as in the presence of different P2X7 antagonists and ionic media. P2X7-mediated phagocytosis was found to account for about half of Latrunculin (or Cytochalasin D)-sensitive bead engulfment by fresh human monocytes. Monocytes harbouring P2X7 Ala348Thr or Glu496Ala polymorphic variants showed increase or loss of ethidium uptake respectively, but these changes in pore formation did not always correspond to the changes in phagocytosis of YG beads. Unlike pore function, P2X7-mediated phagocytosis was not affected by three potent selective P2X7 antagonists and remained identical in Na + and K + media. Taken together, our results show that P2X7 is a scavenger receptor with important function in the CNS but its phagocytic function has features distinct from its pore function. Both P2X7 pore formation and P2X7-mediated phagocytosis should be considered in the design of new P2X7 antagonists for the treatment of CNS diseases. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. P2X receptors, sensory neurons and pain.

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    Bele, Tanja; Fabbretti, Elsa

    2015-01-01

    Pain represents a very large social and clinical problem since the current treatment provides insufficient pain relief. Plasticity of pain receptors together with sensitisation of sensory neurons, and the role of soluble mediators released from non-neuronal cells render difficult to understand the spatial and temporal scale of pain development, neuronal responses and disease progression. In pathological conditions, ATP is one of the most powerful mediators that activates P2X receptors that behave as sensitive ATP-detectors, such as neuronal P2X3 receptor subtypes and P2X4 and P2X7 receptors expressed on non-neuronal cells. Dissecting the molecular mechanisms occurring in sensory neurons and in accessory cells allows to design appropriate tissue- and cell- targeted approaches to treat chronic pain.

  5. P2X7 receptor-mediated PARP1 activity regulates astroglial death in the rat hippocampus following status epilepticus

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    Ji Yang eKim

    2015-09-01

    Full Text Available Poly(ADP-ribose polymerase-1 (PARP1 plays a regulatory role in apoptosis, necrosis, and other cellular processes after injury. Recently, we revealed that PARP1 regulates the differential neuronal/astroglial responses to pilocarpine-induced status epilepticus (SE in the distinct brain regions. In addition, P2X7 receptor (P2X7R, an ATP-gated ion channel, activation accelerates astroglial apoptosis, while it attenuates clasmatodendrosis (lysosome-derived autophagic astroglial death. Therefore, we investigated whether P2X7R regulates regional specific astroglial PARP1 expression/activation in response to SE. In the present study, P2X7R activation exacerbates SE-induced astroglial apoptosis, while P2X7R inhibition attenuates it accompanied by increasing PARP1 activity in the molecular layer of the dentate gyrus following SE. In the CA1 region, however, P2X7R inhibition deteriorates SE-induced clasmatodendrosis via PARP1 activation following SE. Taken together, our findings suggest that P2X7R function may affect SE-induced astroglial death by regulating PARP1 activation/expression in regional-specific manner. Therefore, the selective modulation of P2X7R-mediated PARP1 functions may be a considerable strategy for controls in various types of cell deaths.

  6. Corneal epithelium expresses a variant of P2X(7 receptor in health and disease.

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    Courtney Mankus

    Full Text Available Improper wound repair of the corneal epithelium can alter refraction of light resulting in impaired vision. We have shown that ATP is released after injury, activates purinergic receptor signaling pathways and plays a major role in wound closure. In many cells or tissues, ATP activates P2X(7 receptors leading to cation fluxes and cytotoxicity. The corneal epithelium is an excellent model to study the expression of both the full-length P2X(7 form (defined as the canonical receptor and its truncated forms. When Ca(2+ mobilization is induced by BzATP, a P2X(7 agonist, it is attenuated in the presence of extracellular Mg(2+ or Zn(2+, negligible in the absence of extracellular Ca(2+, and inhibited by the competitive P2X7 receptor inhibitor, A438079. BzATP enhanced phosphorylation of ERK. Together these responses indicate the presence of a canonical or full-length P2X(7 receptor. In addition BzATP enhanced epithelial cell migration, and transfection with siRNA to the P2X(7 receptor reduced cell migration. Furthermore, sustained activation did not induce dye uptake indicating the presence of truncated or variant forms that lack the ability to form large pores. Reverse transcription-polymerase chain reaction and Northern blot analysis revealed a P2X(7 splice variant. Western blots identified a full-length and truncated form, and the expression pattern changed as cultures progressed from monolayer to stratified. Cross-linking gels demonstrated the presence of homo- and heterotrimers. We examined epithelium from age matched diabetic and non-diabetic corneas patients and detected a 4-fold increase in P2X(7 mRNA from diabetic corneal epithelium compared to non-diabetic controls and an increased trend in expression of P2X(7variant mRNA. Taken together, these data indicate that corneal epithelial cells express full-length and truncated forms of P2X(7, which ultimately allows P2X(7 to function as a multifaceted receptor that can mediate cell proliferation and

  7. Blockade of human P2X7 receptor function with a monoclonal antibody.

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    Buell, G; Chessell, I P; Michel, A D; Collo, G; Salazzo, M; Herren, S; Gretener, D; Grahames, C; Kaur, R; Kosco-Vilbois, M H; Humphrey, P P

    1998-11-15

    A monoclonal antibody (MoAb) specific for the human P2X7 receptor was generated in mice. As assessed by flow cytometry, the MoAb labeled human blood-derived macrophage cells natively expressing P2X7 receptors and cells transfected with human P2X7 but not other P2X receptor types. The MoAb was used to immunoprecipitate the human P2X7 receptor protein, and in immunohistochemical studies on human lymphoid tissue, P2X7 receptor labeling was observed within discrete areas of the marginal zone of human tonsil sections. The antibody also acted as a selective antagonist of human P2X7 receptors in several functional studies. Thus, whole cell currents, elicited by the brief application of 2',3'-(4-benzoyl)-benzoyl-ATP in cells expressing human P2X7, were reduced in amplitude by the presence of the MoAb. Furthermore, preincubation of human monocytic THP-1 cells with the MoAb antagonized the ability of P2X7 agonists to induce the release of interleukin-1beta.

  8. Blockade of P2X7 receptors or pannexin-1 channels similarly attenuates postischemic damage.

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    Cisneros-Mejorado, Abraham; Gottlieb, Miroslav; Cavaliere, Fabio; Magnus, Tim; Koch-Nolte, Friederich; Scemes, Eliana; Pérez-Samartín, Alberto; Matute, Carlos

    2015-05-01

    The role of P2X7 receptors and pannexin-1 channels in ischemic damage remains controversial. Here, we analyzed their contribution to postanoxic depolarization after ischemia in cultured neurons and in brain slices. We observed that pharmacological blockade of P2X7 receptors or pannexin-1 channels delayed the onset of postanoxic currents and reduced their slope, and that simultaneous inhibition did not further enhance the effects of blocking either one. These results were confirmed in acute cortical slices from P2X7 and pannexin-1 knockout mice. Oxygen-glucose deprivation in cortical organotypic cultures caused neuronal death that was reduced with P2X7 and pannexin-1 blockers as well as in organotypic cultures derived from mice lacking P2X7 and pannexin 1. Subsequently, we used transient middle cerebral artery occlusion to monitor the neuroprotective effect of those drugs in vivo. We found that P2X7 and pannexin-1 antagonists, and their ablation in knockout mice, substantially attenuated the motor symptoms and reduced the infarct volume to ~50% of that in vehicle-treated or wild-type animals. These results show that P2X7 receptors and pannexin-1 channels are major mediators of postanoxic depolarization in neurons and of brain damage after ischemia, and that they operate in the same deleterious signaling cascade leading to neuronal and tissue demise.

  9. The P2X7 ATP receptor modulates renal cyst development in vitro

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    Hillman, Kate A.; Woolf, Adrian S.; Johnson, Tanya M.; Wade, Angela; Unwin, Robert J.; Winyard, Paul J.D.

    2004-01-01

    P2X 7 , a piercing receptor, is expressed in renal collecting ducts as they undergo fulminant cysto genesis in the cpk/cpk mouse model of autosomal recessive polycystic kidney disease (ARPKD). Dissociated cpk/cpk kidneys generate cysts from cell aggregates within 24 h of suspension culture and we demonstrate that BzATP, a P2X 7 agonist, reduces cystogenesis. This effect is P2X 7 -specific, because: (i) equimolar concentrations of other purinergic agonists, ATP and UTP, had lesser effects and (ii) the P2X 7 inhibitor, oxidized ATP, abrogated the BzATP-mediated reduction in cystogenesis. BzATP did not significantly affect total cell number, proliferation, LDH release or caspase 3 activity, and zVAD-fmk, a caspase blocker, failed to modulate BzATP effects. In addition, this P2X 7 agonist did not significantly alter cyst size, probably excluding altered vectorial transport. In vivo, ATP was detected in cyst fluid from cpk/cpk kidneys; moreover, P2X 7 protein was also upregulated in human fetal ARPKD epithelia versus normal fetal collecting ducts. Thus, ATP may inhibit pathological renal cyst growth through P2X 7 signaling

  10. Prostaglandin E2 potentiation of P2X3 receptor mediated currents in dorsal root ganglion neurons

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    Huang Li-Yen

    2007-08-01

    Full Text Available Abstract Prostaglandin E2 (PGE2 is a well-known inflammatory mediator that enhances the excitability of DRG neurons. Homomeric P2X3 and heteromeric P2X2/3 receptors are abundantly expressed in dorsal root ganglia (DRG neurons and participate in the transmission of nociceptive signals. The interaction between PGE2 and P2X3 receptors has not been well delineated. We studied the actions of PGE2 on ATP-activated currents in dissociated DRG neurons under voltage-clamp conditions. PGE2 had no effects on P2X2/3 receptor-mediated responses, but significantly potentiated fast-inactivating ATP currents mediated by homomeric P2X3 receptors. PGE2 exerted its action by activating EP3 receptors. To study the mechanism underlying the action of PGE2, we found that the adenylyl cyclase activator, forskolin and the membrane-permeable cAMP analogue, 8-Br-cAMP increased ATP currents, mimicking the effect of PGE2. In addition, forskolin occluded the enhancement produced by PGE2. The protein kinase A (PKA inhibitors, H89 and PKA-I blocked the PGE2 effect. In contrast, the PKC inhibitor, bisindolymaleimide (Bis did not change the potentiating action of PGE2. We further showed that PGE2 enhanced α,β-meATP-induced allodynia and hyperalgesia and the enhancement was blocked by H89. These observations suggest that PGE2 binds to EP3 receptors, resulting in the activation of cAMP/PKA signaling pathway and leading to an enhancement of P2X3 homomeric receptor-mediated ATP responses in DRG neurons.

  11. P2X1 receptors and the endothelium

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    LS Harrington

    2005-03-01

    Full Text Available Adenosine triphosphate (ATP is now established as a principle vaso-active mediator in the vasculature. Its actions on arteries are complex, and are mediated by the P2X and P2Y receptor families. It is generally accepted that ATP induces a bi-phasic response in arteries, inducing contraction via the P2X and P2Y receptors on the smooth muscle cells, and vasodilation via the actions of P2Y receptors located on the endothelium. However, a number of recent studies have placed P2X1 receptors on the endothelium of some arteries. The use of a specific P2X1 receptor ligand, a, b methylene ATP has demonstrated that P2X1 receptors also have a bi-functional role. The actions of ATP on P2X1 receptors is therefore dependant on its location, inducing contraction when located on the smooth muscle cells, and dilation when expressed on the endothelium, comparable to that of P2Y receptors.

  12. P2X receptor-mediated ATP purinergic signaling in health and disease

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    Jiang LH

    2012-09-01

    Full Text Available Lin-Hua JiangSchool of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United KingdomAbstract: Purinergic P2X receptors are plasma membrane proteins present in a wide range of mammalian cells where they act as a cellular sensor, enabling cells to detect and respond to extracellular adenosine triphosphate (ATP, an important signaling molecule. P2X receptors function as ligand-gated Ca2+-permeable cationic channels that open upon ATP binding to elevate intracellular Ca2+ concentrations and cause membrane depolarization. In response to sustained activation, P2X receptors induce formation of a pore permeable to large molecules. P2X receptors also interact with distinct functional proteins and membrane lipids to form specialized signaling complexes. Studies have provided compelling evidence to show that such P2X receptor-mediated ATP-signaling mechanisms determine and regulate a growing number and diversity of important physiological processes, including neurotransmission, muscle contraction, and cytokine release. There is accumulating evidence to support strong causative relationships of altered receptor expression and function with chronic pain, inflammatory diseases, cancers, and other pathologies or diseases. Numerous high throughput screening drug discovery programs and preclinical studies have thus far demonstrated the proof of concepts that the P2X receptors are druggable targets and selective receptor antagonism is a promising therapeutics approach. This review will discuss the recent progress in understanding the mammalian P2X receptors with respect to the ATP-signaling mechanisms, physiological and pathophysiological roles, and development and preclinical studies of receptor antagonists.Keywords: extracellular ATP, ion channel, large pore, signaling complex, chronic pain, inflammatory diseases

  13. P2X4: A fast and sensitive purinergic receptor

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    Jaanus Suurväli

    2017-10-01

    Full Text Available Extracellular nucleotides have been recognized as important mediators of activation, triggering multiple responses via plasma membrane receptors known as P2 receptors. P2 receptors comprise P2X ionotropic receptors and G protein-coupled P2Y receptors. P2X receptors are expressed in many tissues, where they are involved in a number of functions including synaptic transmission, muscle contraction, platelet aggregation, inflammation, macrophage activation, differentiation and proliferation, neuropathic and inflammatory pain. P2X4 is one of the most sensitive purinergic receptors (at nanomolar ATP concentrations, about one thousand times more than the archetypal P2X7. P2X4 is widely expressed in central and peripheral neurons, in microglia, and also found in various epithelial tissues and endothelial cells. It localizes on the plasma membrane, but also in intracellular compartments. P2X4 is preferentially localized in lysosomes, where it is protected from proteolysis by its glycosylation. High ATP concentration in the lysosomes does not activate P2X4 at low pH; P2X4 gets activated by intra-lysosomal ATP only in its fully dissociated tetra-anionic form, when the pH increases to 7.4. Thus, P2X4 is functioning as a Ca2+-channel after the fusion of late endosomes and lysosomes. P2X4 modulates major neurotransmitter systems and regulates alcohol-induced responses in microglia. P2X4 is one of the key receptors mediating neuropathic pain. However, injury-induced upregulation of P2X4 expression is gender dependent and plays a key role in pain difference between males and females. P2X4 is also involved in inflammation. Extracellular ATP being a pro-inflammatory molecule, P2X4 can trigger inflammation in response to high ATP release. It is therefore involved in multiple pathologies, like post-ischemic inflammation, rheumatoid arthritis, airways inflammation in asthma, neurodegenerative diseases and even metabolic syndrome. Although P2X4 remains poorly

  14. P2X7 receptor-deficient mice are susceptible to bone cancer pain

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    Hansen, Rikke Rie; Nielsen, Christian K.; Nasser, Arafat

    2011-01-01

    The purinergic P2X7 receptor is implicated in both neuropathic and inflammatory pain, and has been suggested as a possible target in pain treatment. However, the specific role of the P2X7 receptor in bone cancer pain is unknown. We demonstrated that BALB/cJ P2X7 receptor knockout (P2X7R KO) mice...... were susceptible to bone cancer pain and moreover had an earlier onset of pain-related behaviours compared with cancer-bearing, wild-type mice. Furthermore, acute treatment with the selective P2X7 receptor antagonist, A-438079, failed to alleviate pain-related behaviours in models of bone cancer pain...... with and without astrocyte activation (BALB/cJ or C3H mice inoculated with 4T1 mammary cancer cells or NCTC 2472 osteosarcoma cells, respectively), suggesting that astrocytic P2X7 receptors play a negligible role in bone cancer pain. The results support the hypothesis that bone cancer pain is a separate pain state...

  15. P2X7 receptor mediates activation of microglial cells in prostate of chemically irritated rats

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    Heng Zhang

    2013-04-01

    Full Text Available Purpose Evidence shows that adenosine triphosphate (ATP is involved in the transmission of multiple chronic pain via P2X7 receptor. This study was to investigate the P2X7 and microglial cells in the chronic prostatitis pain. Materials and Methods Rats were divided into control group and chronic prostatitis group (n = 24 per group. A chronic prostatitis animal model was established by injecting complete Freund's adjuvant (CFA to the prostate of rats, and the thermal withdrawal latency (TWL was detected on days 0, 4, 12 and 24 (n = 6 at each time point in each group. Animals were sacrificed and the pathological examination of the prostate, detection of mRNA expression of P2X7 and ionized calcium binding adaptor molecule 1 (IBA-1 and measurement of content of tumor necrosis factor-α (TNF-α and interleukin-1β (IL-1β in the dorsal horn of L5-S2 spinal cord were performed on days 0, 4, 12 and 24. In addition, the content of TNF-α and IL-1β in the dorsal horn of L5-S2 spinal cord was measured after intrathecal injection of inhibitors of microglial cells and/or P2X7 for 5 days. Results The chronic prostatitis was confirmed by pathological examination. The expression of P2X7 and IBA-1 and the content of TNF-α and IL-1β in rats with chronic prostatitis were significantly higher than those in the control group. On day 4, the expressions of pro-inflammatory cytokines became to increase, reaching a maximal level on day 12 and started to reduce on day 24, but remained higher than that in the control group. Following suppression of microglial cells and P2X7 receptor, the secretion of TNF-α and IL-1β was markedly reduced. Conclusion In chronic prostatitis pain, the microglial cells and P2X7 receptor are activated resulting in the increased expression of TNF-α and IL-1β in the L5-S2 spinal cord, which might attribute to the maintenance and intensification of pain in chronic prostatitis.

  16. Functional polymorphisms in the P2X7 receptor gene are associated with osteoporosis

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    Husted, L B; Harsløf, T; Stenkjær, L

    2013-01-01

    variant allele, which has been associated with increased receptor function in monocytes, was associated with increased total hip BMD in women. With the exception of His155Tyr for which we found conflicting results in men and women, our results are consistent with the phenotype of the knockout mouse......UNLABELLED: The P2X(7) receptor is an ATP-gated cation channel. We investigated the effect of both loss-of-function and gain-of-function polymorphisms in the P2X(7) receptor gene on BMD and risk of vertebral fractures and found that five polymorphisms and haplotypes containing three...... of these polymorphisms were associated with BMD and fracture risk. INTRODUCTION: The P2X(7) receptor is an ATP-gated cation channel. P2X(7) receptor knockout mice have reduced total bone mineral content, and because several functional polymorphisms have been identified in the human P2X(7) receptor gene, we wanted...

  17. Differential expression of the P2X7 receptor in ovarian surface epithelium during the oestrous cycle in the mouse.

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    Vázquez-Cuevas, F G; Cruz-Rico, A; Garay, E; García-Carrancá, A; Pérez-Montiel, D; Juárez, B; Arellano, R O

    2013-01-01

    Purinergic signalling has been proposed as an intraovarian regulatory mechanism. Of the receptors responsible for purinergic transmission, the P2X7 receptor is an ATP-gated cationic channel that displays a broad spectrum of cellular functions ranging from apoptosis to cell proliferation and tumourigenesis. In the present study, we investigated the functional expression of P2X7 receptors in ovarian surface epithelium (OSE). P2X7 protein was detected in the OSE layer of the mouse, both in situ and in primary cultures. In cultures, 2'(3')-O-(4-Benzoylbenzoyl)adenosine-5'-triphosphate (BzATP) activation of P2X7 receptors increased [Ca(2+)]i and induced apoptosis. The functionality of the P2X7 receptor was investigated in situ by intrabursal injection of BzATP on each day of the oestrous cycle and evaluation of apoptosis 24h using the terminal deoxyribonucleotidyl transferase-mediated dUTP-fluorescein nick end-labelling (TUNEL) assay. Maximum effects of BzATP were observed during pro-oestrus, with the effects being blocked by A438079, a specific P2X7 receptor antagonist. Immunofluorescence staining for P2X7 protein revealed more robust expression during pro-oestrus and in OSE regions behind the antral follicles, strongly supporting the notion that the differences in apoptosis can be explained by increased receptor expression, which is regulated during the oestrous cycle. Finally, P2X7 receptor expression was detected in the OSE layer of human ovaries, with receptor expression maintained in human ovaries diagnosed with cancer, as well as in the human ovarian carcinoma SKOV3 cell line.

  18. P2X7 receptor-mediated calcium dynamics in HEK293 cells: experimental characterization and modelling approach

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    Di Garbo, A; Alloisio, S; Nobile, M

    2012-01-01

    The P2X7 receptor (P2X7R) induces ionotropic Ca 2+  signalling in different cell types. It plays an important role in the immune response and in the nervous system. Here, the mechanisms underlying intracellular Ca 2+  variations evoked by 3′-O-(4-benzoyl)benzoyl-ATP (BzATP), a potent agonist of the P2X7R, in transfected HEK293 cells, are investigated both experimentally and theoretically. We propose a minimal model of P2X7R that is capable of reproducing, qualitatively and quantitatively, the experimental data. This approach was also adopted for the P2X7R variant, which lacks the entire C-terminus tail (trP2X7R). Then we introduce a biophysical model describing the Ca 2+  dynamics in HEK293. Our model gives an account of the ionotropic Ca 2+  influx evoked by BzATP on the basis of the kinetics model of P2X7R. To explain the complex Ca 2+  responses evoked by BzATP, the model predicted that an impairment in Ca 2+  extrusion flux through the plasma membrane is a key factor for Ca 2+ homeostasis in HEK293 cells. (paper)

  19. P2X7 receptor-mediated calcium dynamics in HEK293 cells: experimental characterization and modelling approach

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    Di Garbo, A.; Alloisio, S.; Nobile, M.

    2012-04-01

    The P2X7 receptor (P2X7R) induces ionotropic Ca2 + signalling in different cell types. It plays an important role in the immune response and in the nervous system. Here, the mechanisms underlying intracellular Ca2 + variations evoked by 3‧-O-(4-benzoyl)benzoyl-ATP (BzATP), a potent agonist of the P2X7R, in transfected HEK293 cells, are investigated both experimentally and theoretically. We propose a minimal model of P2X7R that is capable of reproducing, qualitatively and quantitatively, the experimental data. This approach was also adopted for the P2X7R variant, which lacks the entire C-terminus tail (trP2X7R). Then we introduce a biophysical model describing the Ca2 + dynamics in HEK293. Our model gives an account of the ionotropic Ca2 + influx evoked by BzATP on the basis of the kinetics model of P2X7R. To explain the complex Ca2 + responses evoked by BzATP, the model predicted that an impairment in Ca2 + extrusion flux through the plasma membrane is a key factor for Ca2 + homeostasis in HEK293 cells.

  20. Pilocarpine-Induced Status Epilepticus Increases the Sensitivity of P2X7 and P2Y1 Receptors to Nucleotides at Neural Progenitor Cells of the Juvenile Rodent Hippocampus.

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    Rozmer, Katalin; Gao, Po; Araújo, Michelle G L; Khan, Muhammad Tahir; Liu, Juan; Rong, Weifang; Tang, Yong; Franke, Heike; Krügel, Ute; Fernandes, Maria José S; Illes, Peter

    2017-07-01

    Patch-clamp recordings indicated the presence of P2X7 receptors at neural progenitor cells (NPCs) in the subgranular zone of the dentate gyrus in hippocampal brain slices prepared from transgenic nestin reporter mice. The activation of these receptors caused inward current near the resting membrane potential of the NPCs, while P2Y1 receptor activation initiated outward current near the reversal potential of the P2X7 receptor current. Both receptors were identified by biophysical/pharmacological methods. When the brain slices were prepared from mice which underwent a pilocarpine-induced status epilepticus or when brain slices were incubated in pilocarpine-containing external medium, the sensitivity of P2X7 and P2Y1 receptors was invariably increased. Confocal microscopy confirmed the localization of P2X7 and P2Y1 receptor-immunopositivity at nestin-positive NPCs. A one-time status epilepticus in rats caused after a latency of about 5 days recurrent epileptic fits. The blockade of central P2X7 receptors increased the number of seizures and their severity. It is hypothesized that P2Y1 receptors after a status epilepticus may increase the ATP-induced proliferation/ectopic migration of NPCs; the P2X7 receptor-mediated necrosis/apoptosis might counteract these effects, which would otherwise lead to a chronic manifestation of recurrent epileptic fits. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  1. P2X7 receptor activates extracellular signal-regulated kinases ERK1 and ERK2 independently of Ca2+ influx

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    Amstrup, Jan; Novak, Ivana

    2003-01-01

    P2X7 nucleotide receptors modulate a spectrum of cellular events in various cells including epithelia, such as exocrine pancreas. Although the pharmacology and channel properties of the P2X7 receptors have been studied intensively, signal transduction pathways are relatively unknown. In this study...... we applied a heterologous expression system of rat P2X7 receptors in HEK-293 cells. We followed the receptor expression and function using the enhanced green fluorescent protein (EGFP) tag, activation of intracellular proteins and increases in cellular Ca2+. EGFP-P2X7 receptors localized...... to the plasma membrane, clusters within the membrane and intracellularly. Stimulation of P2X7 receptors in HEK-293 cells led to an activation of extracellular signal-regulated kinases ERK1 and ERK2 and this activation was seen after just 1 min of stimulation with ATP. Using C- and N-terminal P2X7-receptor...

  2. P2X7 receptor activation ameliorates CA3 neuronal damage via a tumor necrosis factor-α-mediated pathway in the rat hippocampus following status epilepticus

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    Ryu Hea Jin

    2011-06-01

    Full Text Available Abstract Background The release of tumor necrosis factor-α (TNF-α appears depend on the P2X7 receptor, a purinergic receptor. In the present study, we addressed the question of whether P2X7 receptor-mediated TNF-α regulation is involved in pathogenesis and outcome of status epilepticus (SE. Methods SE was induced by pilocarpine in rats that were intracerebroventricularly infused with saline-, 2',3'-O-(4-benzoylbenzoyl-adenosine 5'-triphosphate (BzATP, adenosine 5'-triphosphate-2',3'-dialdehyde (OxATP, A-438079, or A-740003 prior to SE induction. Thereafter, we performed Fluoro-Jade B staining and immunohistochemical studies for TNF-α and NF-κB subunit phosphorylations. Results Following SE, P2X7 receptor agonist (BzATP infusion increased TNF-α immunoreactivity in dentate granule cells as compared with that in saline-infused animals. In addition, TNF-α immunoreactivity was readily apparent in the mossy fibers, while TNF-α immunoreactivity in CA1-3 pyramidal cells was unaltered. However, P2X7 receptor antagonist (OxATP-, A-438079, and A-740003 infusion reduced SE-induced TNF-α expression in dentate granule cells. In the CA3 region, BzATP infusion attenuated SE-induced neuronal damage, accompanied by enhancement of p65-Ser276 and p65-Ser311 NF-κB subunit phosphorylations. In contrast, OxATP-, A-438079, and A-740003 infusions increased SE-induced neuronal death. Soluble TNF p55 receptor (sTNFp55R, and cotreatment with BzATP and sTNFp55R infusion also increased SE-induced neuronal damage in CA3 region. However, OxATP-, sTNFp55R or BzATP+sTNFp55R infusions could not exacerbate SE-induced neuronal damages in the dentate gyrus and the CA1 region, as compared to BzATP infusion. Conclusions These findings suggest that TNF-α induction by P2X7 receptor activation may ameliorate SE-induced CA3 neuronal damage via enhancing NF-κB p65-Ser276 and p65-Ser311 phosphorylations.

  3. Non-nucleotide Agonists Triggering P2X7 Receptor Activation and Pore Formation

    Directory of Open Access Journals (Sweden)

    Francesco Di Virgilio

    2018-02-01

    Full Text Available The P2X7 receptor (P2X7R is a ligand-gated plasma membrane ion channel belonging to the P2X receptor subfamily activated by extracellular nucleotides. General consensus holds that the physiological (and maybe the only agonist is ATP. However, scattered evidence generated over the last several years suggests that ATP might not be the only agonist, especially at inflammatory sites. Solid data show that NAD+ covalently modifies the P2X7R of mouse T lymphocytes, thus lowering the ATP threshold for activation. Other structurally unrelated agents have been reported to activate the P2X7R via a poorly understood mechanism of action: (a the antibiotic polymyxin B, possibly a positive allosteric P2X7R modulator, (b the bactericidal peptide LL-37, (c the amyloidogenic β peptide, and (d serum amyloid A. Some agents, such as Alu-RNA, have been suggested to activate the P2X7R acting on the intracellular N- or C-terminal domains. Mode of P2X7R activation by these non-nucleotide ligands is as yet unknown; however, these observations raise the intriguing question of how these different non-nucleotide ligands may co-operate with ATP at inflammatory or tumor sites. New information obtained from the cloning and characterization of the P2X7R from exotic mammalian species (e.g., giant panda and data from recent patch-clamp studies are strongly accelerating our understanding of P2X7R mode of operation, and may provide hints to the mechanism of activation of P2X7R by non-nucleotide ligands.

  4. Statins and ATP regulate nuclear pAkt via the P2X7 purinergic receptor in epithelial cells

    International Nuclear Information System (INIS)

    Mistafa, Oras; Hoegberg, Johan; Stenius, Ulla

    2008-01-01

    Many studies have documented P2X7 receptor functions in cells of mesenchymal origin. P2X7 is also expressed in epithelial cells and its role in these cells remains largely unknown. Our data indicate that P2X7 regulate nuclear pAkt in epithelial cells. We show that low concentration of atorvastatin, a drug inhibiting HMG-CoA reductase and cholesterol metabolism, or the natural agonist extracellular ATP rapidly decreased the level of insulin-induced phosphorylated Akt in the nucleus. This effect was seen within minutes and was inhibited by P2X7 inhibitors. Experiments employing P2X7 siRNA and HEK293 cells heterologously expressing P2X7 and in vivo experiments further supported an involvement of P2X7. These data indicate that extracellular ATP and statins via the P2X7 receptor modulate insulin-induced Akt signaling in epithelial cells

  5. Statins and ATP regulate nuclear pAkt via the P2X7 purinergic receptor in epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Mistafa, Oras; Hoegberg, Johan [Institute of Environmental Medicine, Karolinska Institutet, Box 210, 17177 Stockholm (Sweden); Stenius, Ulla [Institute of Environmental Medicine, Karolinska Institutet, Box 210, 17177 Stockholm (Sweden)

    2008-01-04

    Many studies have documented P2X7 receptor functions in cells of mesenchymal origin. P2X7 is also expressed in epithelial cells and its role in these cells remains largely unknown. Our data indicate that P2X7 regulate nuclear pAkt in epithelial cells. We show that low concentration of atorvastatin, a drug inhibiting HMG-CoA reductase and cholesterol metabolism, or the natural agonist extracellular ATP rapidly decreased the level of insulin-induced phosphorylated Akt in the nucleus. This effect was seen within minutes and was inhibited by P2X7 inhibitors. Experiments employing P2X7 siRNA and HEK293 cells heterologously expressing P2X7 and in vivo experiments further supported an involvement of P2X7. These data indicate that extracellular ATP and statins via the P2X7 receptor modulate insulin-induced Akt signaling in epithelial cells.

  6. Effect of P2X(7) receptor knockout on exocrine secretion of pancreas, salivary glands and lacrimal glands.

    Science.gov (United States)

    Novak, Ivana; Jans, Ida M; Wohlfahrt, Louise

    2010-09-15

    The purinergic P2X(7) receptors are expressed in different cell types where they have varied functions, including regulation of cell survival. The P2X(7) receptors are also expressed in exocrine glands, but their integrated role in secretion is unclear. The aim of our study was to determine whether the P2X(7) receptors affect fluid secretion in pancreas, salivary glands and tear glands. We monitored gland secretions in in vivo preparations of wild-type and P2X(7)(-/-) (Pfizer) mice stimulated with pilocarpine. In cell preparations from pancreas, parotid and lacrimal glands we measured ATP release and intracellular Ca(2+) activity using Fura-2. The data showed that pancreatic secretion and salivary secretions were reduced in P2X(7)(-/-) mice, and in contrast, tear secretion was increased in P2X(7)(-/-) mice. The secretory phenotype was also dependent on the sex of the animal, such that males were more dependent on the P2X(7) receptor expression. ATP release in all cell preparations could be elicited by carbachol and other agonists, and this was independent of the P2X(7) receptor expression. ATP and carbachol increased intracellular Ca(2+) activity, but responses depended on the gland type, presence of the P2X(7) receptor and the sex of the animal. Together, these results demonstrate that cholinergic stimulation leads to release of ATP that can via P2X(7) receptors up-regulate pancreatic and salivary secretion but down-regulate tear secretion. Our data also indicate that there is an interaction between purinergic and cholinergic receptor signalling and that function of the P2X(7) receptor is suppressed in females. We conclude that the P2X(7) receptors are important in short-term physiological regulation of exocrine gland secretion.

  7. Effect of P2X7 receptor knockout on exocrine secretion of pancreas, salivary glands and lacrimal glands

    Science.gov (United States)

    Novak, Ivana; Jans, Ida M; Wohlfahrt, Louise

    2010-01-01

    The purinergic P2X7 receptors are expressed in different cell types where they have varied functions, including regulation of cell survival. The P2X7 receptors are also expressed in exocrine glands, but their integrated role in secretion is unclear. The aim of our study was to determine whether the P2X7 receptors affect fluid secretion in pancreas, salivary glands and tear glands. We monitored gland secretions in in vivo preparations of wild-type and P2X7−/− (Pfizer) mice stimulated with pilocarpine. In cell preparations from pancreas, parotid and lacrimal glands we measured ATP release and intracellular Ca2+ activity using Fura-2. The data showed that pancreatic secretion and salivary secretions were reduced in P2X7−/− mice, and in contrast, tear secretion was increased in P2X7−/− mice. The secretory phenotype was also dependent on the sex of the animal, such that males were more dependent on the P2X7 receptor expression. ATP release in all cell preparations could be elicited by carbachol and other agonists, and this was independent of the P2X7 receptor expression. ATP and carbachol increased intracellular Ca2+ activity, but responses depended on the gland type, presence of the P2X7 receptor and the sex of the animal. Together, these results demonstrate that cholinergic stimulation leads to release of ATP that can via P2X7 receptors up-regulate pancreatic and salivary secretion but down-regulate tear secretion. Our data also indicate that there is an interaction between purinergic and cholinergic receptor signalling and that function of the P2X7 receptor is suppressed in females. We conclude that the P2X7 receptors are important in short-term physiological regulation of exocrine gland secretion. PMID:20643770

  8. Deletion of P2X2 and P2X3 receptor subunits does not alter motility of the mouse colon

    Directory of Open Access Journals (Sweden)

    Matthew DeVries

    2010-03-01

    Full Text Available Purinergic P2X receptors contribute to neurotransmission in the gut. P2X receptors are ligand-gated cation channels that mediate synaptic excitation in subsets of enteric neurons. The present study evaluated colonic motility in vitro and in vivo in wild type (WT and P2X2 and P2X3 subunit knockout (KO mice. The muscarinic receptor agonist, bethanechol (0.3-3 micromolar, caused similar contractions of the longitudinal muscle in colon segments from WT, P2X2 and P2X3 subunit KO mice. Nicotine (1-300 micromolar, acting at neuronal nicotinic receptors, caused similar longitudinal muscle relaxations in colonic segments from WT and P2X2 and P2X3 subunit KO mice. Nicotine-induced relaxations were inhibited by nitro-L-arginine (NLA, 100 micromolar and apamin (0.1 micromolar which block inhibitory neuromuscular transmission. ATP (1-1000 micromolar caused contractions only in the presence of NLA and apamin. ATP-induced contractions were similar in colon segments from WT, P2X2 and P2X3 KO mice. The mouse colon generates spontaneous migrating motor complexes (MMCs in vitro. The MMC frequency was higher in P2X2 KO compared to WT tissues; other parameters of the MMC were similar in colon segments from WT, P2X2 and P2X3 KO mice. 5-Hydroxytryptophan-induced fecal output was similar in WT, P2X2 and P2X3 KO mice. These data indicate that nicotinic receptors are located predominately on inhibitory motor neurons supplying the longitudinal muscle in the mouse colon. P2X2 or P2X3 subunit containing receptors are not localized to motorneurons supplying the longitudinal muscle. Synaptic transmission mediated by P2X2 or P2X3 subunit containing receptors is not required for propulsive motility in the mouse colon.

  9. Lack of the purinergic receptor P2X7 results in resistance to contact hypersensitivity

    Science.gov (United States)

    Weber, Felix C.; Esser, Philipp R.; Müller, Tobias; Ganesan, Jayanthi; Pellegatti, Patrizia; Simon, Markus M.; Zeiser, Robert; Idzko, Marco; Jakob, Thilo

    2010-01-01

    Sensitization to contact allergens requires activation of the innate immune system by endogenous danger signals. However, the mechanisms through which contact allergens activate innate signaling pathways are incompletely understood. In this study, we demonstrate that mice lacking the adenosine triphosphate (ATP) receptor P2X7 are resistant to contact hypersensitivity (CHS). P2X7-deficient dendritic cells fail to induce sensitization to contact allergens and do not release IL-1β in response to lipopolysaccharide (LPS) and ATP. These defects are restored by pretreatment with LPS and alum in an NLRP3- and ASC-dependent manner. Whereas pretreatment of wild-type mice with P2X7 antagonists, the ATP-degrading enzyme apyrase or IL-1 receptor antagonist, prevents CHS, IL-1β injection restores CHS in P2X7-deficient mice. Thus, P2X7 is a crucial receptor for extracellular ATP released in skin in response to contact allergens. The lack of P2X7 triggering prevents IL-1β release, which is an essential step in the sensitization process. Interference with P2X7 signaling may be a promising strategy for the prevention of allergic contact dermatitis. PMID:21059855

  10. Direct labelling of the human P2X7 receptor and identification of positive and negative cooperativity of binding.

    Science.gov (United States)

    Michel, A D; Chambers, L J; Clay, W C; Condreay, J P; Walter, D S; Chessell, I P

    2007-05-01

    The P2X(7) receptor exhibits complex pharmacological properties. In this study, binding of a [(3)H]-labelled P2X(7) receptor antagonist to human P2X(7) receptors has been examined to further understand ligand interactions with this receptor. The P2X(7) receptor antagonist, N-[2-({2-[(2-hydroxyethyl)amino]ethyl}amino)-5-quinolinyl]-2-tricyclo[3.3.1.1(3,7)]dec-1-ylacetamide (compound-17), was radiolabelled with tritium and binding studies were performed using membranes prepared from U-2 OS or HEK293 cells expressing human recombinant P2X(7) receptors. Binding of [(3)H]-compound-17 was higher in membranes prepared from cells expressing P2X(7) receptors than from control cells and was inhibited by ATP suggesting labelled sites represented human P2X(7) receptors. Binding was reversible, saturable and modulated by P2X(7) receptor ligands (Brilliant Blue G, KN62, ATP, decavanadate). Furthermore, ATP potency was reduced in the presence of divalent cations or NaCl. Radioligand binding exhibited both positive and negative cooperativity. Positive cooperativity was evident from bell shaped Scatchard plots, reduction in radioligand dissociation rate by unlabelled compound-17 and enhancement of radioligand binding by KN62 and unlabelled compound-17. ATP and decavanadate inhibited binding in a negative cooperative manner as they enhanced radioligand dissociation. These data demonstrate that human P2X(7) receptors can be directly labelled and provide novel insights into receptor function. The positive cooperativity observed suggests that binding of compound-17 to one subunit in the P2X(7) receptor complex enhances subsequent binding to other P2X(7) subunits in the same complex. The negative cooperative effects of ATP suggest that ATP and compound-17 bind at separate, interacting, sites on the P2X(7) receptor.

  11. Structural basis for subtype-specific inhibition of the P2X7 receptor

    Energy Technology Data Exchange (ETDEWEB)

    Karasawa, Akira; Kawate, Toshimitsu (Cornell)

    2016-12-09

    <p>The P2X7 receptor is a non-selective cation channel activated by extracellular adenosine triphosphate (ATP). Chronic activation of P2X7 underlies many health problems such as pathologic pain, yet we lack effective antagonists due to poorly understood mechanisms of inhibition. Here we present crystal structures of a mammalian P2X7 receptor complexed with five structurally-unrelated antagonists. Unexpectedly, these drugs all bind to an allosteric site distinct from the ATP-binding pocket in a groove formed between two neighboring subunits. This novel drug-binding pocket accommodates a diversity of small molecules mainly through hydrophobic interactions. Functional assays propose that these compounds allosterically prevent narrowing of the drug-binding pocket and the turret-like architecture during channel opening, which is consistent with a site of action distal to the ATP-binding pocket. These novel mechanistic insights will facilitate the development of P2X7-specific drugs for treating human diseases.p>

  12. Localization of P2X receptor subtypes 2, 3 and 7 in human urinary bladder.

    Science.gov (United States)

    Svennersten, Karl; Hallén-Grufman, Katarina; de Verdier, Petra J; Wiklund, N Peter; Poljakovic, Mirjana

    2015-08-08

    Voiding dysfunctions are a common problem that has a severe negative impact on the quality of life. Today there is a need for new drug targets for these conditions. The role of ATP receptors in bladder physiology has been studied for some time, primarily in animal models. The aim of this work is to investigate the localization of the ATP receptors P2X2, P2X3 and P2X7 and their colocalization with vimentin and actin in the human urinary bladder. Immunohistochemical analysis was conducted on full-thickness bladder tissues from fundus and trigonum collected from 15 patients undergoing open radical cystectomy due to chronic cystitis, bladder cancer or locally advanced prostate cancer. Colocalization analyses were performed between the three different P2X subtypes and the structural proteins vimentin and actin. Specimens were examined using epifluorescence microscopy and correlation coefficients were calculated for each costaining as well as the mean distance from the laminin positive basal side of the urothelium to the vimentin positive cells located in the suburothelium. P2X2 was expressed in vimentin positive cells located in the suburothelium. Less distinct labelling of P2X2 was also observed in actin positive smooth muscle cells and in the urothelium. P2X3 was expressed in vimentin positive cells surrounding the smooth muscle, and in vimentin positive cells located in the suburothelium. Weaker P2X3 labelling was seen in the urothelium. P2X7 was expressed in the smooth muscle cells and the urothelium. In the suburothelium, cells double positive for P2X2 and vimentin where located closer to the urothelium while cells double positive for P2X3 and vimentin where located further from the urothelium. The results from this study demonstrate that there is a significant difference in the expression of the purinergic P2X2, P2X3 and P2X7 receptors in the different histological layers of the human urinary bladder.

  13. Interaction of GABAA receptors with purinergic P2X2 receptors

    International Nuclear Information System (INIS)

    Shrivastava, A.

    2010-01-01

    GABA A Rs in the spinal cord are evolving as an important target for drug development against pain. Purinergic P2X 2 Rs are also expressed in spinal cord neurons and are known to cross-talk with GABA A Rs. Here we investigated a possible 'dynamic' interaction between GABA A Rs and P2X 2 Rs using co-immunoprecipitation and FRET studies in HEK cells along with co-localization and single particle tracking studies in spinal cord neurons. Our results suggest that a significant proportion of P2X 2 Rs forms a transient complex with GABA A Rs inside the cell, thus stabilizing these receptors and using them for co-trafficking to the cell surface. P2X 2 Rs and GABA A Rs are then co-inserted into the cell membrane and are primarily located extra-synaptically. Furthermore, agonist induced activation of P2X 2 Rs results in disassembly of the receptor complex and destabilization of GABA A Rs whereas P2X 2 Rs are stabilized and form larger clusters. Antagonist-induced blocking of P2XRs results in co-stabilization of this receptor complex at the cell surface. These results suggest a novel mechanism where association of P2XRs with other receptors could be used for specific targeting to the neuronal membrane, thus providing an extrasynaptic receptor reserve that could regulate the excitability of neurons. We further conclude that blocking the excitatory activity of excessively released ATP under diseased state by P2XR antagonists could simultaneously enhance synaptic inhibition mediated by GABA A Rs.(author) (author) [de

  14. P2X7 receptors regulate multiple types of membrane trafficking responses and non-classical secretion pathways.

    Science.gov (United States)

    Qu, Yan; Dubyak, George R

    2009-06-01

    Activation of the P2X7 receptor (P2X7R) triggers a remarkably diverse array of membrane trafficking responses in leukocytes and epithelial cells. These responses result in altered profiles of cell surface lipid and protein composition that can modulate the direct interactions of P2X7R-expressing cells with other cell types in the circulation, in blood vessels, at epithelial barriers, or within sites of immune and inflammatory activation. Additionally, these responses can result in the release of bioactive proteins, lipids, and large membrane complexes into extracellular compartments for remote communication between P2X7R-expressing cells and other cells that amplify or modulate inflammation, immunity, and responses to tissue damages. This review will discuss P2X7R-mediated effects on membrane composition and trafficking in the plasma membrane (PM) and intracellular organelles, as well as actions of P2X7R in controlling various modes of non-classical secretion. It will review P2X7R regulation of: (1) phosphatidylserine distribution in the PM outer leaflet; (2) shedding of PM surface proteins; (3) release of PM-derived microvesicles or microparticles; (4) PM blebbing; (5) cell-cell fusion resulting in formation of multinucleate cells; (6) phagosome maturation and fusion with lysosomes; (7) permeability of endosomes with internalized pathogen-associated molecular patterns; (8) permeability/integrity of mitochondria; (9) exocytosis of secretory lysosomes; and (10) release of exosomes from multivesicular bodies.

  15. The P2X7 receptor regulates cell survival, migration and invasion of pancreatic ductal adenocarcinoma cells

    DEFF Research Database (Denmark)

    Giannuzzo, Andrea; Pedersen, Stine Helene Falsig; Novak, Ivana

    2015-01-01

    of the ATP receptors, the P2X7 receptor (P2X7R) could be an important player in PDAC behaviour. METHODS: We determined the expression (real time PCR and Western blot) and localization (immunofluorescence) of P2X7R in human PDAC cell lines (AsPC-1, BxPC-3, Capan-1, MiaPaCa-2, Panc-1) and a "normal" human...

  16. Activation of P2X7-mediated apoptosis Inhibits DMBA/TPA-induced formation of skin papillomas and cancer in mice

    International Nuclear Information System (INIS)

    Fu, Wen; Gorodeski, George I; McCormick, Tom; Qi, Xiaoping; Luo, Liping; Zhou, Lingyin; Li, Xin; Wang, Bing-Cheng; Gibbons, Heidi E; Abdul-Karim, Fadi W

    2009-01-01

    augmented calcium influx were depended on the expression of the P2X 7 receptor, while the BzATP-induced apoptosis depended on calcium influx. (h) The BzATP-induced apoptosis could be blocked by co-treatment with inhibitors of caspase-9 and caspase-3, but not of caspase-8. (a) P2X 7 -dependent apoptosis is an important mechanism that controls the development and progression of epidermal neoplasia in the mouse. (b) The P2X 7 -dependent apoptosis is mediated by calcium influx via P2X 7 pores, and involves the caspase-9 (mitochondrial) pathway. (c) The diminished pro-apoptotic effect of BzATP in mouse cancer keratinocytes is possibly the result of low expression of the P2X 7 receptor. (d) Activation of P2X 7 -dependent apoptosis, e.g. with BzATP could be a novel chemotherapeutic growth-preventive modality for papillomas and epithelial cancers in vivo

  17. Post-translational regulation of P2X receptor channels: modulation by phospholipids

    Directory of Open Access Journals (Sweden)

    Louis-Philippe eBernier

    2013-11-01

    Full Text Available P2X receptor channels mediate fast excitatory signaling by ATP and play major roles in sensory transduction, neuro-immune communication and inflammatory response. P2X receptors constitute a gene family of calcium-permeable ATP-gated cation channels therefore the regulation of P2X signaling is critical for both membrane potential and intracellular calcium homeostasis. Phosphoinositides (PIPn are anionic signaling phospholipids that act as functional regulators of many types of ion channels. Direct PIPn binding was demonstrated for several ligand- or voltage-gated ion channels, however no generic motif emerged to accurately predict lipid-protein binding sites. This review presents what is currently known about the modulation of the different P2X subtypes by phospholipids and about critical determinants underlying their sensitivity to PIPn levels in the plasma membrane.All functional mammalian P2X subtypes tested, with the notable exception of P2X5, have been shown to be positively modulated by PIPn, i.e. homomeric P2X1, P2X2, P2X3, P2X4, and P2X7, as well as heteromeric P2X1/5 and P2X2/3 receptors. Based on various results reported on the aforementioned subtypes including mutagenesis of the prototypical PIPn-sensitive P2X4 and PIPn-insensitive P2X5 receptor subtypes, an increasing amount of functional, biochemical and structural evidence converges on the modulatory role of a short polybasic domain located in the proximal C-terminus of P2X subunits. This linear motif, semi-conserved in the P2X family, seems necessary and sufficient for encoding direct modulation of ATP-gated channels by PIPn. Furthermore, the physiological impact of the regulation of ionotropic purinergic responses by phospholipids on pain pathways was recently revealed in the context of native crosstalks between phospholipase C-linked metabotropic receptors and P2X receptor channels in DRG sensory neurons and microglia.

  18. Nociceptive transmission and modulation via P2X receptors in central pain syndrome.

    Science.gov (United States)

    Kuan, Yung-Hui; Shyu, Bai-Chuang

    2016-05-26

    Painful sensations are some of the most frequent complaints of patients who are admitted to local medical clinics. Persistent pain varies according to its causes, often resulting from local tissue damage or inflammation. Central somatosensory pathway lesions that are not adequately relieved can consequently cause central pain syndrome or central neuropathic pain. Research on the molecular mechanisms that underlie this pathogenesis is important for treating such pain. To date, evidence suggests the involvement of ion channels, including adenosine triphosphate (ATP)-gated cation channel P2X receptors, in central nervous system pain transmission and persistent modulation upon and following the occurrence of neuropathic pain. Several P2X receptor subtypes, including P2X2, P2X3, P2X4, and P2X7, have been shown to play diverse roles in the pathogenesis of central pain including the mediation of fast transmission in the peripheral nervous system and modulation of neuronal activity in the central nervous system. This review article highlights the role of the P2X family of ATP receptors in the pathogenesis of central neuropathic pain and pain transmission. We discuss basic research that may be translated to clinical application, suggesting that P2X receptors may be treatment targets for central pain syndrome.

  19. P2X7 receptor activation induces cell death and microparticle release in murine erythroleukemia cells.

    NARCIS (Netherlands)

    Constantinescu, P.; Wang, B.; Kovacevic, K.; Jalilian, I.; Bosman, G.J.C.G.M.; Wiley, J.S.; Sluyter, R.

    2010-01-01

    Extracellular ATP induces cation fluxes in and impairs the growth of murine erythroleukemia (MEL) cells in a manner characteristic of the purinergic P2X7 receptor, however the presence of P2X7 in these cells is unknown. This study investigated whether MEL cells express functional P2X7. RT-PCR,

  20. Hyperglycemia-induced Renal P2X7 Receptor Activation Enhances Diabetes-related Injury

    Directory of Open Access Journals (Sweden)

    Robert I. Menzies

    2017-05-01

    Full Text Available Diabetes is a leading cause of renal disease. Glomerular mesangial expansion and fibrosis are hallmarks of diabetic nephropathy and this is thought to be promoted by infiltration of circulating macrophages. Monocyte chemoattractant protein-1 (MCP-1 has been shown to attract macrophages in kidney diseases. P2X7 receptors (P2X7R are highly expressed on macrophages and are essential components of pro-inflammatory signaling in multiple tissues. Here we show that in diabetic patients, renal P2X7R expression is associated with severe mesangial expansion, impaired glomerular filtration (≤40 ml/min/1.73 sq. m., and increased interstitial fibrosis. P2X7R activation enhanced the release of MCP-1 in human mesangial cells cultured under high glucose conditions. In mice, P2X7R-deficiency prevented glomerular macrophage attraction and collagen IV deposition; however, the more severe interstitial inflammation and fibrosis often seen in human diabetic kidney diseases was not modelled. Finally, we demonstrate that a P2X7R inhibitor (AZ11657312 can reduce renal macrophage accrual following the establishment of hyperglycemia in a model of diabetic nephropathy. Collectively these data suggest that P2X7R activation may contribute to the high prevalence of kidney disease found in diabetics.

  1. Towards a Novel Class of Multitarget-Directed Ligands: Dual P2X7–NMDA Receptor Antagonists

    Directory of Open Access Journals (Sweden)

    Olga Karoutzou

    2018-01-01

    Full Text Available Multi-target-directed ligands (MTDLs offer new hope for the treatment of multifactorial complex diseases such as Alzheimer’s Disease (AD. Herein, we present compounds aimed at targeting the NMDA and the P2X7 receptors, which embody a different approach to AD therapy. On one hand, we are seeking to delay neurodegeneration targeting the glutamatergic NMDA receptors; on the other hand, we also aim to reduce neuroinflammation, targeting P2X7 receptors. Although the NMDA receptor is a widely recognized therapeutic target in treating AD, the P2X7 receptor remains largely unexplored for this purpose; therefore, the dual inhibitor presented herein—which is open to further optimization—represents the first member of a new class of MTDLs.

  2. Activation of P2X7-mediated apoptosis Inhibits DMBA/TPA-induced formation of skin papillomas and cancer in mice

    Directory of Open Access Journals (Sweden)

    Fu Wen

    2009-04-01

    BzATP. (g Pore formation and the augmented calcium influx were depended on the expression of the P2X7 receptor, while the BzATP-induced apoptosis depended on calcium influx. (h The BzATP-induced apoptosis could be blocked by co-treatment with inhibitors of caspase-9 and caspase-3, but not of caspase-8. Conclusion (a P2X7-dependent apoptosis is an important mechanism that controls the development and progression of epidermal neoplasia in the mouse. (b The P2X7-dependent apoptosis is mediated by calcium influx via P2X7 pores, and involves the caspase-9 (mitochondrial pathway. (c The diminished pro-apoptotic effect of BzATP in mouse cancer keratinocytes is possibly the result of low expression of the P2X7 receptor. (d Activation of P2X7-dependent apoptosis, e.g. with BzATP could be a novel chemotherapeutic growth-preventive modality for papillomas and epithelial cancers in vivo.

  3. The role of P2X receptors in bone biology.

    Science.gov (United States)

    Jørgensen, N R; Syberg, S; Ellegaard, M

    2015-01-01

    Bone is a highly dynamic organ, being constantly modeled and remodeled in order to adapt to the changing need throughout life. Bone turnover involves the coordinated actions of bone formation and bone degradation. Over the past decade great effort has been put into the examination of how P2X receptors regulate bone metabolism and especially for the P2X7 receptor an impressive amount of evidence has now documented its expression in osteoblasts, osteoclasts, and osteocytes as well as important functional roles in proliferation, differentiation, and function of the cells of bone. Key evidence has come from studies on murine knockout models and from pharmacologic studies on cells and animals. More recently, the role of P2X receptors in human bone diseases has been documented. Loss-of-functions polymorphisms in the P2X7 receptorare associated with bone loss and increased fracture risk. Very recently a report from a genetic study in multiple myeloma demonstrated that decreased P2X7 receptor function was associated with increased risk of developing multiple myeloma. In contrast, the risk of developing myeloma bone disease and subsequent vertebral fractures was increased in subjects carrying P2X7 receptor gain-of-function alleles as compared to subjects only carrying loss-of-function or normal functioning alleles. It is evident that P2X receptors are important in regulating bone turnover and maintaining bone mass, and thereby holding great potential as novel drug targets for treatment of bone diseases. However, further research is needed before we fully understand the roles and effects of P2X receptors in bone.

  4. P2X receptors in the cardiovascular system and their potential as therapeutic targets in disease.

    Science.gov (United States)

    Ralevic, Vera

    2015-01-01

    This review considers the expression and roles of P2X receptors in the cardiovascular system in health and disease and their potential as therapeutic targets. P2X receptors are ligand gated ion channels which are activated by the endogenous ligand ATP. They are formed from the assembly of three P2X subunit proteins from the complement of seven (P2X1-7), which can associate to form homomeric or heteromeric P2X receptors. The P2X1 receptor is widely expressed in the cardiovascular system, being located in the heart, in the smooth muscle of the majority of blood vessels and in platelets. P2X1 receptors expressed in blood vessels can be activated by ATP coreleased with noradrenaline as a sympathetic neurotransmitter, leading to smooth muscle depolarisation and contraction. There is evidence that the purinergic component of sympathetic neurotransmission is increased in hypertension, identifying P2X1 receptors as a possible therapeutic target in this disorder. P2X3 and P2X2/3 receptors are expressed on cardiac sympathetic neurones and may, through positive feedback of neuronal ATP at this prejunctional site, amplify sympathetic neurotransmission. Activation of P2X receptors expressed in the heart increases cardiac myocyte contractility, and an important role of the P2X4 receptor in this has been identified. Deletion of P2X4 receptors in the heart depresses contractile performance in models of heart failure, while overexpression of P2X4 receptors has been shown to be cardioprotective, thus P2X4 receptors may be therapeutic targets in the treatment of heart disease. P2X receptors have been identified on endothelial cells. Although immunoreactivity for all P2X1-7 receptor proteins has been shown on the endothelium, relatively little is known about their function, with the exception of the endothelial P2X4 receptor, which has been shown to mediate endothelium-dependent vasodilatation to ATP released during shear stress. The potential of P2X receptors as therapeutic targets

  5. Lack of neuroprotection in the absence of P2X7 receptors in toxin-induced animal models of Parkinson's disease

    Directory of Open Access Journals (Sweden)

    Kittel Ágnes

    2011-05-01

    Full Text Available Abstract Background Previous studies indicate a role of P2X7 receptors in processes that lead to neuronal death. The main objective of our study was to examine whether genetic deletion or pharmacological blockade of P2X7 receptors influenced dopaminergic cell death in various models of Parkinson's disease (PD. Results mRNA encoding P2X7 and P2X4 receptors was up-regulated after treatment of PC12 cells with 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP. P2X7 antagonists protected against MPTP and rotenone induced toxicity in the LDH assay, but failed to protect after rotenone treatment in the MTT assay in PC12 cells and in primary midbrain culture. In vivo MPTP and in vitro rotenone pretreatments increased the mRNA expression of P2X7 receptors in the striatum and substantia nigra of wild-type mice. Basal mRNA expression of P2X4 receptors was higher in P2X7 knockout mice and was further up-regulated by MPTP treatment. Genetic deletion or pharmacological inhibition of P2X7 receptors did not change survival rate or depletion of striatal endogenous dopamine (DA content after in vivo MPTP or in vitro rotenone treatment. However, depletion of norepinephrine was significant after MPTP treatment only in P2X7 knockout mice. The basal ATP content was higher in the substantia nigra of wild-type mice, but the ADP level was lower. Rotenone treatment elicited a similar reduction in ATP content in the substantia nigra of both genotypes, whereas reduction of ATP was more pronounced after rotenone treatment in striatal slices of P2X7 deficient mice. Although the endogenous amino acid content remained unchanged, the level of the endocannabinoid, 2-AG, was elevated by rotenone in the striatum of wild-type mice, an effect that was absent in mice deficient in P2X7 receptors. Conclusions We conclude that P2X7 receptor deficiency or inhibition does not support the survival of dopaminergic neurons in an in vivo or in vitro models of PD.

  6. Propensity of red blood cells to undergo P2X7 receptor-mediated phosphatidylserine exposure does not alter during in vivo or ex vivo aging.

    Science.gov (United States)

    Sophocleous, Reece A; Mullany, Phillip R F; Winter, Kelly M; Marks, Denese C; Sluyter, Ronald

    2015-08-01

    Phosphatidylserine (PS) exposure facilitates the removal of red blood cells (RBCs) from the circulation, potentially contributing to the loss of stored RBCs after transfusion, as well as senescent RBCs. Activation of the P2X7 receptor by extracellular adenosine 5'-triphosphate (ATP) can induce PS exposure on freshly isolated human RBCs, but whether this process occurs in stored RBCs or changes during RBC aging is unknown. RBCs were processed and stored according to Australian blood banking guidelines. PS exposure was determined by annexin V binding and flow cytometry. Efficacy of P2X antagonists was assessed by flow cytometric measurements of ATP-induced ethidium+ uptake in RPMI 8226 cells. Osmotic fragility was assessed by lysis in hypotonic saline. RBCs were fractionated by discontinuous density centrifugation. ATP (1 mmol/L) induced PS exposure on RBCs stored for less than 1 week. This process was near-completely inhibited by the P2X7 antagonists A438079 and AZ10606120 and the P2X1/P2X7 antagonist MRS2159 but not the P2X1 antagonist NF499. ATP-induced PS exposure on RBCs was not dependent on K+, Na+, or Cl- fluxes. ATP did not alter the osmotic fragility of stored RBCs. ATP-induced PS exposure was similar between RBCs of different densities. ATP-induced PS exposure was also similar between RBCs stored for less than 1 week or for 6 weeks. The propensity of RBCs to undergo P2X7-mediated PS exposure does not alter during in vivo and ex vivo aging. Thus, P2X7 activation is unlikely to be involved in the removal of senescent RBCs or stored RBCs after transfusion. © 2015 AABB.

  7. Oxygen/glucose deprivation increases the integration of recombinant P2X7 receptors into the plasma membrane of HEK293 cells

    International Nuclear Information System (INIS)

    Milius, Doreen; Groeger-Arndt, Helke; Stanchev, Doychin; Lange-Dohna, Christine; Rossner, Steffen; Sperlagh, Beata; Wirkner, Kerstin; Illes, Peter

    2007-01-01

    Recombinant human P2X 7 receptors, C-terminally labelled with enhanced green fluorescent protein (P2X 7 -EGFP), were transiently expressed in HEK293 cells. Activation of these receptors by their preferential agonist 2',3'-O-(4-benzoylbenzoyl)-ATP (BzATP) induced inward currents and propidium ion uptake indicating the opening of cationic channels and of large pores permeable for dye molecules, respectively. Two mutants of P2X 7 receptors (P2X 7 -EGFP-I568N, -E496A) representing polymorphisms in the P2X 7 gene known to interfere with normal receptor-trafficking and with optimal assembly of its subunits, responded with much lower current amplitudes to BzATP than their wild-type counterpart. Similarly, the normal propidium ion uptake induced by BzATP at the wild-type P2X 7 receptor was abolished by the two mutants. Confocal laser scanning microscopy indicated that in vitro ischemia of 12 h duration increased the integration of P2X 7 -EGFP, but not of its two mutants, into the plasma membrane of HEK293 cells. Further, this ischemic stimulus facilitated the current response to BzATP in HEK293 cells permanently transfected with P2X 7 receptors. Finally, the fluorescence intensity per cell measured by flow cytometry and P2X 7 antibodies directed against an extracellular, but not an intracellular epitope of the receptor, were also increased. In conclusion, P2X 7 receptors may alter their trafficking properties during ischemia and thereby contribute to the ATP-induced damage of various cell-types including neurons

  8. The P2X7 Receptor Supports Both Life and Death in Fibrogenic Pancreatic Stellate Cells

    DEFF Research Database (Denmark)

    Haanes, Kristian; Schwab, Albrecht; Novak, Ivana

    2012-01-01

    The pancreatic stellate cells (PSCs) have complex roles in pancreas, including tissue repair and fibrosis. PSCs surround ATP releasing exocrine cells, but little is known about purinergic receptors and their function in PSCs. Our aim was to resolve whether PSCs express the multifunctional P2X7...... versions of the receptor. In culture, the proliferation rate of the KO PSCs was significantly lower. Inclusion of apyrase reduced the proliferation rate in both WT and KO PSCs, indicating importance of endogenous ATP. Exogenous ATP had a two-sided effect. Proliferation of both WT and KO cells...... inhibitor az10606120. The P2X7 receptor-pore inhibitor A438079 partially prevented cell death induced by millimolar ATP concentrations. This study shows that ATP and P2X7 receptors are important regulators of PSC proliferation and death, and therefore might be potential targets for treatments of pancreatic...

  9. Inflammatory early events associated to the role of P2X7 receptor in acute murine toxoplasmosis.

    Science.gov (United States)

    Corrêa, Gladys; Almeida Lindenberg, Carolina de; Moreira-Souza, Aline Cristina de Abreu; Savio, Luiz Eduardo Baggio; Takiya, Christina Maeda; Marques-da-Silva, Camila; Vommaro, Rossiane Claudia; Coutinho-Silva, Robson

    2017-04-01

    Activation of the purinergic P2X7 receptor by extracellular ATP (eATP) potentiates proinflammatory responses during infections by intracellular pathogens. Extracellular ATP triggers an antimicrobial response in macrophages infected with Toxoplasma gondii in vitro, suggesting that purinergic signaling may stimulate host defense mechanisms against toxoplasmosis. Here, we provide in vivo evidence in support of this hypothesis, by showing that P2X7 -/- mice are more susceptible than P2X7 +/+ mice to acute infection by the RH strain of T. gondii, and that this phenomenon is associated with a deficient proinflammatory response. Four days post-infection, peritoneal washes from infected P2X7 -/- mice had no or little increase in the levels of the proinflammatory cytokines IL-12, IL-1β, IFN-γ, and TNF-α, whose levels increased markedly in samples from infected P2X7 +/+ mice. Infected P2X7 -/- mice displayed an increase in organ weight and histological alterations in some of the 'shock organs' in toxoplasmosis - the liver, spleen and mesenteric lymph nodes. The liver of infected P2X7 -/- mice had smaller granulomas, but increased parasite load/granuloma. Our results confirm that the P2X7 receptor is involved in containing T. gondii spread in vivo, by stimulating inflammation. Copyright © 2016 Elsevier GmbH. All rights reserved.

  10. Purinergní P2X rodina a specifické vlastnosti P2X7 podtypu

    Czech Academy of Sciences Publication Activity Database

    Jindřichová, Marie; Zemková, Hana

    2013-01-01

    Roč. 62, č. 2 (2013), s. 40-46 ISSN 1210-6313 R&D Projects: GA ČR(CZ) GPP304/12/P371 Institutional support: RVO:67985823 Keywords : extracellular ATP * purinergic P2X family * P2X7 receptor * cell proliferation and apoptosis Subject RIV: ED - Physiology

  11. Paracrine stimulation of P2X7 receptor by ATP activates a proliferative pathway in ovarian carcinoma cells.

    Science.gov (United States)

    Vázquez-Cuevas, Francisco G; Martínez-Ramírez, Angélica S; Robles-Martínez, Leticia; Garay, Edith; García-Carrancá, Alejandro; Pérez-Montiel, Delia; Castañeda-García, Carolina; Arellano, Rogelio O

    2014-11-01

    P2X7 is a purinergic receptor-channel; its activation by ATP elicits a broad set of cellular actions, from apoptosis to signals for survival. Here, P2X7 expression and function was studied in human ovarian carcinoma (OCA) cells, and biopsies from non-cancerous and cancer patients were analyzed by immunohistochemistry. Ovarian surface epithelium in healthy tissue expressed P2X7 at a high level that was maintained throughout the cancer. The cell lines SKOV-3 and CAOV-3 were used to investigate P2X7 functions in OCA. In SKOV-3 cells, selective stimulation of P2X7 by 2'(3')-O-(4-benzoylbenzoyl) adenosine-5'-triphosphate (BzATP) induced a dose-dependent increase of intracellular Ca(2+) concentration ([Ca(2+)](i)) but not cell death. Instead, BzATP increased the levels of phosphorylated ERK and AKT (pERK and pAKT), with an EC(50) of 44 ± 2 and 1.27 ± 0.5 μM, respectively; 10 μM BzATP evoked a maximum effect within 15 min that lasted for 120 min. Interestingly, basal levels of pERK and pAKT were decreased in the presence of apyrase in the medium, strongly suggesting an endogenous, ATP-mediated phenomenon. Accordingly: (i) mechanically stimulated cells generated a [Ca(2+)](i) increase that was abolished by apyrase; (ii) apyrase induced a decrease in culture viability, as measured by the MTS assay for mitochondrial activity; and (iii) incubation with 10 μM AZ10606120, a specific P2X7 antagonist and transfection with the dominant negative P2X7 mutant E496A, both reduced cell viability to 70.1 ± 8.9% and to 76.5 ± 5%, respectively, of control cultures. These observations suggested that P2X7 activity was auto-induced through ATP efflux; this increased pERK and pAKT levels that generated a positive feedback on cell viability. © 2014 Wiley Periodicals, Inc.

  12. The role of P2X receptors in bone biology

    DEFF Research Database (Denmark)

    Jørgensen, N R; Syberg, S; Ellegaard, M

    2015-01-01

    receptors regulate bone metabolism and especially for the P2X7 receptor an impressive amount of evidence has now documented its expression in osteoblasts, osteoclasts, and osteocytes as well as important functional roles in proliferation, differentiation, and function of the cells of bone. Key evidence has...... come from studies on murine knockout models and from pharmacologic studies on cells and animals. More recently, the role of P2X receptors in human bone diseases has been documented. Loss-of-functions polymorphisms in the P2X7 receptorare associated with bone loss and increased fracture risk. Very...

  13. Impaired P2X1 Receptor-Mediated Adhesion in Eosinophils from Asthmatic Patients.

    Science.gov (United States)

    Wright, Adam; Mahaut-Smith, Martyn; Symon, Fiona; Sylvius, Nicolas; Ran, Shaun; Bafadhel, Mona; Muessel, Michelle; Bradding, Peter; Wardlaw, Andrew; Vial, Catherine

    2016-06-15

    Eosinophils play an important role in the pathogenesis of asthma and can be activated by extracellular nucleotides released following cell damage or inflammation. For example, increased ATP concentrations were reported in bronchoalveolar lavage fluids of asthmatic patients. Although eosinophils are known to express several subtypes of P2 receptors for extracellular nucleotides, their function and contribution to asthma remain unclear. In this article, we show that transcripts for P2X1, P2X4, and P2X5 receptors were expressed in healthy and asthmatic eosinophils. The P2X receptor agonist α,β-methylene ATP (α,β-meATP; 10 μM) evoked rapidly activating and desensitizing inward currents (peak 18 ± 3 pA/pF at -60 mV) in healthy eosinophils, typical of P2X1 homomeric receptors, which were abolished by the selective P2X1 antagonist NF449 (1 μM) (3 ± 2 pA/pF). α,β-meATP-evoked currents were smaller in eosinophils from asthmatic patients (8 ± 2 versus 27 ± 5 pA/pF for healthy) but were enhanced following treatment with a high concentration of the nucleotidase apyrase (17 ± 5 pA/pF for 10 IU/ml and 11 ± 3 pA/pF for 0.32 IU/ml), indicating that the channels are partially desensitized by extracellular nucleotides. α,β-meATP (10 μM) increased the expression of CD11b activated form in eosinophils from healthy, but not asthmatic, donors (143 ± 21% and 108 ± 11% of control response, respectively). Furthermore, α,β-meATP increased healthy (18 ± 2% compared with control 10 ± 1%) but not asthmatic (13 ± 1% versus 10 ± 0% for control) eosinophil adhesion. Healthy human eosinophils express functional P2X1 receptors whose activation leads to eosinophil αMβ2 integrin-dependent adhesion. P2X1 responses are constitutively reduced in asthmatic compared with healthy eosinophils, probably as the result of an increase in extracellular nucleotide concentration. Copyright © 2016 by The American Association of Immunologists, Inc.

  14. Bone phenotypes of P2 receptor knockout mice

    DEFF Research Database (Denmark)

    Orriss, Isabel; Syberg, Susanne; Wang, Ning

    2011-01-01

    The action of extracellular nucleotides is mediated by ionotropic P2X receptors and G-protein coupled P2Y receptors. The human genome contains 7 P2X and 8 P2Y receptor genes. Knockout mice strains are available for most of them. As their phenotypic analysis is progressing, bone abnormalities have...... been observed in an impressive number of these mice: distinct abnormalities in P2X7-/- mice, depending on the gene targeting construct and the genetic background, decreased bone mass in P2Y1-/- mice, increased bone mass in P2Y2-/- mice, decreased bone resorption in P2Y6-/- mice, decreased bone...... formation and bone resorption in P2Y13-/- mice. These findings demonstrate the unexpected importance of extracellular nucleotide signalling in the regulation of bone metabolism via multiple P2 receptors and distinct mechanisms involving both osteoblasts and osteoclasts....

  15. P2X receptors as targets for the treatment of status epilepticus

    Science.gov (United States)

    Henshall, David C.; Diaz-Hernandez, Miguel; Miras-Portugal, M. Teresa; Engel, Tobias

    2013-01-01

    Prolonged seizures are amongst the most common neurological emergencies. Status epilepticus is a state of continuous seizures that is life-threatening and prompt termination of status epilepticus is critical to protect the brain from permanent damage. Frontline treatment comprises parenteral administration of anticonvulsants such as lorazepam that facilitate γ-amino butyric acid (GABA) transmission. Because status epilepticus can become refractory to anticonvulsants in a significant proportion of patients, drugs which act on different neurotransmitter systems may represent potential adjunctive treatments. P2X receptors are a class of ligand-gated ion channel activated by ATP that contributes to neuro- and glio-transmission. P2X receptors are expressed by both neurons and glia in various brain regions, including the hippocampus. Electrophysiology, pharmacology and genetic studies suggest certain P2X receptors are activated during pathologic brain activity. Expression of several members of the family including P2X2, P2X4, and P2X7 receptors has been reported to be altered in the hippocampus following status epilepticus. Recent studies have shown that ligands of the P2X7 receptor can have potent effects on seizure severity during status epilepticus and mice lacking this receptor display altered seizures in response to chemoconvulsants. Antagonists of the P2X7 receptor also modulate neuronal death, microglial responses and neuroinflammatory signaling. Recent work also found altered neuronal injury and inflammation after status epilepticus in mice lacking the P2X4 receptor. In summary, members of the P2X receptor family may serve important roles in the pathophysiology of status epilepticus and represent novel targets for seizure control and neuroprotection. PMID:24324404

  16. Heterozygosity for the Mood Disorder-Associated Variant Gln460Arg Alters P2X7 Receptor Function and Sleep Quality.

    Science.gov (United States)

    Metzger, Michael W; Walser, Sandra M; Dedic, Nina; Aprile-Garcia, Fernando; Jakubcakova, Vladimira; Adamczyk, Marek; Webb, Katharine J; Uhr, Manfred; Refojo, Damian; Schmidt, Mathias V; Friess, Elisabeth; Steiger, Axel; Kimura, Mayumi; Chen, Alon; Holsboer, Florian; Arzt, Eduardo; Wurst, Wolfgang; Deussing, Jan M

    2017-11-29

    A single nucleotide polymorphism substitution from glutamine (Gln, Q) to arginine (Arg, R) at codon 460 of the purinergic P2X7 receptor (P2X7R) has repeatedly been associated with mood disorders. The P2X7R-Gln460Arg variant per se is not compromised in its function. However, heterologous expression of P2X7R-Gln460Arg together with wild-type P2X7R has recently been demonstrated to impair receptor function. Here we show that this also applies to humanized mice coexpressing both human P2X7R variants. Primary hippocampal cells derived from heterozygous mice showed an attenuated calcium uptake upon agonist stimulation. While humanized mice were unaffected in their behavioral repertoire under basal housing conditions, mice that harbor both P2X7R variants showed alterations in their sleep quality resembling signs of a prodromal disease stage. Also healthy heterozygous human subjects showed mild changes in sleep parameters. These results indicate that heterozygosity for the wild-type P2X7R and its mood disorder-associated variant P2X7R-Gln460Arg represents a genetic risk factor, which is potentially able to convey susceptibility to mood disorders. SIGNIFICANCE STATEMENT Depression and bipolar disorder are the most common mood disorders. The P2X7 receptor (P2X7R) regulates many cellular functions. Its polymorphic variant Gln460Arg has repeatedly been associated with mood disorders. Genetically engineered mice, with human P2X7R, revealed that heterozygous mice (i.e., they coexpress the disease-associated Gln460Arg variant together with its normal version) have impaired receptor function and showed sleep disturbances. Human participants with the heterozygote genotype also had subtle alterations in their sleep profile. Our findings suggest that altered P2X7R function in heterozygote individuals disturbs sleep and might increase the risk for developing mood disorders. Copyright © 2017 the authors 0270-6474/17/3711688-13$15.00/0.

  17. P2X receptor-ion channels in the inflammatory response in adipose tissue and pancreas-potential triggers in onset of type 2 diabetes?

    DEFF Research Database (Denmark)

    Novak, Ivana; Solini, Anna

    2018-01-01

    -cell and adipose tissue. In the former, P2Y and possibly some P2X receptors-ion channels regulate insulin secretion, but it is still debated whether excessive ATP can via P2X receptors impair β-cell function directly or whether cell damage is due to an excessive systemic release of cytokines. In human adipocytes......, the P2X7 receptor promotes the release of inflammatory cytokines, at least in part via inflammasome activation, likely contributing to systemic insulin resistance. This receptor-inflammasome system is also strongly activated in macrophages infiltrating both pancreas and adipose tissue, mediating...

  18. Dual Gating Mechanism and Function of P2X7 Receptor Channels

    Czech Academy of Sciences Publication Activity Database

    Khadra, A.; Tomic, M.; Yan, Z.; Zemková, Hana; Sherman, A.; Stojilkovic, S. S.

    2013-01-01

    Roč. 104, č. 12 (2013), s. 2612-2621 ISSN 0006-3495 R&D Projects: GA ČR(CZ) GBP304/12/G069 Institutional support: RVO:67985823 Keywords : purinergic P2X7 receptors * ATP-gated channels * BzATP * dilation * Markov -state model Subject RIV: ED - Physiology Impact factor: 3.832, year: 2013

  19. Modulation of Central Synapses by Astrocyte-Released ATP and Postsynaptic P2X Receptors

    Science.gov (United States)

    Pankratov, Yuriy

    2017-01-01

    Communication between neuronal and glial cells is important for neural plasticity. P2X receptors are ATP-gated cation channels widely expressed in the brain where they mediate action of extracellular ATP released by neurons and/or glia. Recent data show that postsynaptic P2X receptors underlie slow neuromodulatory actions rather than fast synaptic transmission at brain synapses. Here, we review these findings with a particular focus on the release of ATP by astrocytes and the diversity of postsynaptic P2X-mediated modulation of synaptic strength and plasticity in the CNS. PMID:28845311

  20. Acidic pH facilitates peripheral αβmeATP-mediated nociception in rats: differential roles of P2X, P2Y, ASIC and TRPV1 receptors in ATP-induced mechanical allodynia and thermal hyperalgesia.

    Science.gov (United States)

    Seo, Hyoung-Sig; Roh, Dae-Hyun; Kwon, Soon-Gu; Yoon, Seo-Yeon; Kang, Suk-Yun; Moon, Ji-Young; Choi, Sheu-Ran; Beitz, Alvin J; Lee, Jang-Hern

    2011-03-01

    Peripheral ischemia is commonly associated with an increase in tissue ATP concentration and a decrease in tissue pH. Although in vitro data suggest that low tissue pH can affect ATP-binding affinities to P2 receptors, the mechanistic relationship between ATP and low pH on peripheral nociception has not been fully examined. This study was designed to investigate the potential role of an acidified environment on intraplantar αβmeATP-induced peripheral pain responses in rats. The mechanical allodynia (MA) produced by injection of αβmeATP was significantly increased in animals that received the drug diluted in pH 4.0 saline compared to those that received the drug diluted in pH 7.0 saline. Moreover, animals injected with αβmeATP (100 nmol) in pH 4.0 saline developed thermal hyperalgesia (TH), which did not occur in animals treated with αβmeATP diluted in pH 7.0 saline. To elucidate which receptors were involved in this pH-related facilitation of αβmeATP-induced MA and TH, rats were pretreated with PPADS (P2 antagonist), TNP-ATP (P2X antagonist), MRS2179 (P2Y1 antagonist), AMG9810 (TRPV1 antagonist) or amiloride (ASIC blocker). Both PPADS and TNP-ATP dose-dependently blocked pH-facilitated MA, while TH was significantly reduced by pre-treatment with MRS2179 or AMG9810. Moreover, amiloride injection significantly reduced low pH-induced facilitation of αβmeATP-mediated MA, but not TH. These results demonstrate that low tissue pH facilitates ATP-mediated MA via the activation of P2X receptors and ASICs, whereas TH induced by ATP under low pH conditions is mediated by the P2Y1 receptor and TRPV1, but not ASIC. Thus distinct mechanisms are responsible for the development of MA and TH under conditions of tissue acidosis and increased ATP. Copyright © 2010 Elsevier Ltd. All rights reserved.

  1. P2X receptors in epithelia

    DEFF Research Database (Denmark)

    Leipziger, Jens Georg

    2015-01-01

    P2X receptors are ubiquitously expressed in all epithelial tissues but their functional roles are less well studied. Here we review the current state of knowledge by focusing on functional effects of P2X receptor in secretory and in absorptive tissues. In glandular tissue like the parotid gland...

  2. Modulation of Central Synapses by Astrocyte-Released ATP and Postsynaptic P2X Receptors

    Directory of Open Access Journals (Sweden)

    Eric Boué-Grabot

    2017-01-01

    Full Text Available Communication between neuronal and glial cells is important for neural plasticity. P2X receptors are ATP-gated cation channels widely expressed in the brain where they mediate action of extracellular ATP released by neurons and/or glia. Recent data show that postsynaptic P2X receptors underlie slow neuromodulatory actions rather than fast synaptic transmission at brain synapses. Here, we review these findings with a particular focus on the release of ATP by astrocytes and the diversity of postsynaptic P2X-mediated modulation of synaptic strength and plasticity in the CNS.

  3. 3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) disrupts blood-brain barrier integrity through a mechanism involving P2X7 receptors.

    Science.gov (United States)

    Rubio-Araiz, Ana; Perez-Hernandez, Mercedes; Urrutia, Andrés; Porcu, Francesca; Borcel, Erika; Gutierrez-Lopez, Maria Dolores; O'Shea, Esther; Colado, Maria Isabel

    2014-08-01

    The recreational drug 3,4-methylenedioxymethamphetamine (MDMA; 'ecstasy') produces a neuro-inflammatory response in rats characterized by an increase in microglial activation and IL-1β levels. The integrity of the blood-brain barrier (BBB) is important in preserving the homeostasis of the brain and has been shown to be affected by neuro-inflammatory processes. We aimed to study the effect of a single dose of MDMA on the activity of metalloproteinases (MMPs), expression of extracellular matrix proteins, BBB leakage and the role of the ionotropic purinergic receptor P2X7 (P2X7R) in the changes induced by the drug. Adult male Dark Agouti rats were treated with MDMA (10 mg/kg, i.p.) and killed at several time-points in order to evaluate MMP-9 and MMP-3 activity in the hippocampus and laminin and collagen-IV expression and IgG extravasation in the dentate gyrus. Microglial activation, P2X7R expression and localization were also determined in the dentate gyrus. Separate groups were treated with MDMA and the P2X7R antagonists Brilliant Blue G (BBG; 50 mg/kg, i.p.) or A-438079 (30 mg/kg, i.p.). MDMA increased MMP-3 and MMP-9 activity, reduced laminin and collagen-IV expression and increased IgG immunoreactivity. In addition, MDMA increased microglial activation and P2X7R immunoreactivity in these cells. BBG suppressed the increase in MMP-9 and MMP-3 activity, prevented basal lamina degradation and IgG extravasation into the brain parenchyma. A-438079 also prevented the MDMA-induced reduction in laminin and collagen-IV immunoreactivity. These results indicate that MDMA alters BBB permeability through an early P2X7R-mediated event, which in turn leads to enhancement of MMP-9 and MMP-3 activity and degradation of extracellular matrix.

  4. Effect of P2X(7) receptor knockout on exocrine secretion of pancreas, salivary glands and lacrimal glands

    DEFF Research Database (Denmark)

    Novak, Ivana; Jans, Ida M; Wohlfahrt, Louise

    2010-01-01

    the P2X(7) receptors affect fluid secretion in pancreas, salivary glands and tear glands. We monitored gland secretions in in vivo preparations of wild-type and P2X(7)(-/-) (Pfizer) mice stimulated with pilocarpine. In cell preparations from pancreas, parotid and lacrimal glands we measured ATP release...... and intracellular Ca(2+) activity using Fura-2. The data showed that pancreatic secretion and salivary secretions were reduced in P2X(7)(-/-) mice, and in contrast, tear secretion was increased in P2X(7)(-/-) mice. The secretory phenotype was also dependent on the sex of the animal, such that males were more...

  5. An Improved Method for P2X7R Antagonist Screening.

    Directory of Open Access Journals (Sweden)

    Rômulo José Soares-Bezerra

    Full Text Available ATP physiologically activates the P2X7 receptor (P2X7R, a member of the P2X ionotropic receptor family. When activated by high concentrations of ATP (i.e., at inflammation sites, this receptor is capable of forming a pore that allows molecules of up to 900 Da to pass through. This receptor is upregulated in several diseases, particularly leukemia, rheumatoid arthritis and Alzheimer's disease. A selective antagonist of this receptor could be useful in the treatment of P2X7R activation-related diseases. In the present study, we have evaluated several parameters using in vitro protocols to validate a high-throughput screening (HTS method to identify P2X7R antagonists. We generated dose-response curves to determine the EC50 value of the known agonist ATP and the ICs50 values for the known antagonists Brilliant Blue G (BBG and oxidized ATP (OATP. The values obtained were consistent with those found in the literature (0.7 ± 0.07 mM, 1.3-2.6 μM and 173-285 μM for ATP, BBG and OATP, respectively [corrected].The Z-factor, an important statistical tool that can be used to validate the robustness and suitability of an HTS assay, was 0.635 for PI uptake and 0.867 for LY uptake. No inter-operator variation was observed, and the results obtained using our improved method were reproducible. Our data indicate that our assay is suitable for the selective and reliable evaluation of P2X7 activity in multiwell plates using spectrophotometry-based methodology. This method might improve the high-throughput screening of conventional chemical or natural product libraries for possible candidate P2X7R antagonist or agonist.

  6. Intercellular calcium signaling occurs between human osteoblasts and osteoclasts and requires activation of osteoclast P2X7 receptors

    DEFF Research Database (Denmark)

    Jørgensen, Niklas R; Henriksen, Zanne; Sørensen, Ole

    2002-01-01

    that human osteoclasts expressed functional P2Y1 receptors, but, unexpectedly, desensitization of P2Y1 did not block calcium signaling to osteoclasts. We also found that osteoclasts expressed functional P2X7 receptors and showed that pharmacological inhibition of these receptors blocked calcium signaling...

  7. Microglia P2Y13 Receptors Prevent Astrocyte Proliferation Mediated by P2Y1 Receptors

    Directory of Open Access Journals (Sweden)

    Clara Quintas

    2018-05-01

    Full Text Available Cerebral inflammation is a common feature of several neurodegenerative diseases that requires a fine interplay between astrocytes and microglia to acquire appropriate phenotypes for an efficient response to neuronal damage. During brain inflammation, ATP is massively released into the extracellular medium and converted into ADP. Both nucleotides acting on P2 receptors, modulate astrogliosis through mechanisms involving microglia-astrocytes communication. In previous studies, primary cultures of astrocytes and co-cultures of astrocytes and microglia were used to investigate the influence of microglia on astroglial proliferation induced by ADPβS, a stable ADP analog. In astrocyte cultures, ADPβS increased cell proliferation through activation of P2Y1 and P2Y12 receptors, an effect abolished in co-cultures (of astrocytes with ∼12.5% microglia. The possibility that the loss of the ADPβS-mediated effect could have been caused by a microglia-induced degradation of ADPβS or by a preferential microglial localization of P2Y1 or P2Y12 receptors was excluded. Since ADPβS also activates P2Y13 receptors, the contribution of microglial P2Y13 receptors to prevent the proliferative effect of ADPβS in co-cultures was investigated. The results obtained indicate that P2Y13 receptors are low expressed in astrocytes and mainly expressed in microglia. Furthermore, in co-cultures, ADPβS induced astroglial proliferation in the presence of the selective P2Y13 antagonist MRS 2211 (3 μM and of the selective P2Y12 antagonist AR-C66096 (0.1 μM, suggesting that activation of microglial P2Y12 and P2Y13 receptors may induce the release of messengers that inhibit astroglial proliferation mediated by P2Y1,12 receptors. In this microglia-astrocyte paracrine communication, P2Y12 receptors exert opposite effects in astroglial proliferation as a result of its cellular localization: cooperating in astrocytes with P2Y1 receptors to directly stimulate proliferation and in

  8. P2X7 receptor regulates osteoclast function and bone loss in a mouse model of osteoporosis

    DEFF Research Database (Denmark)

    Wang, Ning; Agrawal, Ankita; Jørgensen, Niklas Rye

    2018-01-01

    Post-menopausal osteoporosis is a condition that affects millions worldwide and places a huge socio-economic burden on society. Previous research has shown an association of loss of function SNPs in the gene for the purinergic receptor P2X7R with low bone mineral density, increased rates of bone...... loss and vertebral fractures in post-menopausal women. In this study we use a mouse model of oestrogen deficiency-induced bone loss and the BALB/cJ P2X7R-/- to show that absence of the P2X7R resulted in increased bone loss. Osteoclast precursors were isolated from both BALB/cJ P2X7R-/- and BALB/cJ P2X7......R+/+ mice and then cultured in vitro to form mature resorbing osteoclasts. The BALB/cJ P2X7R-/- derived precursors generated slightly more osteoclasts but with a significant reduction in the amount of resorption per osteoclast. Furthermore, when using modified culture conditions osteoclast activity...

  9. Association of P2X7 receptor polymorphisms with bone mineral density and osteoporosis risk in a cohort of Dutch fracture patients

    DEFF Research Database (Denmark)

    Wesselius, A; Bours, M J L; Henriksen, Z

    2013-01-01

    The P2X(7) receptor is thought to be involved in bone physiology in a pro-osteogenic manner. Therefore, we examined associations between genetic variations in the P2X(7) receptor gene and bone mineral density (BMD). We found an association between four non-synonymous polymorphism of the human P2X...

  10. P2X7, NMDA and BDNF receptors converge on GSK3 phosphorylation and cooperate to promote survival in cerebellar granule neurons.

    Science.gov (United States)

    Ortega, Felipe; Pérez-Sen, Raquel; Morente, Verónica; Delicado, Esmerilda G; Miras-Portugal, Maria Teresa

    2010-05-01

    Glycogen synthase kinase-3 (GSK3) is a key player in the regulation of neuronal survival. Herein, we report evidence of an interaction between P2X7 receptors with NMDA and BDNF receptors at the level of GSK3 signalling and neuroprotection. The activation of these receptors in granule neurons led to a sustained pattern of GSK3 phosphorylation that was mainly PKC-dependent. BDNF was the most potent at inducing GSK3 phosphorylation, which was also dependent on PI3K. The P2X7 agonist, BzATP, exhibited additive effects with both NMDA and BDNF to rescue granule neurons from cell death induced by PI3K inhibition. This survival effect was mediated by the PKC-dependent GSK3 pathway. In addition, ERK1/2 proteins were also involved in BDNF protective effect. These results show the function of ATP in amplifying neuroprotective actions of glutamate and neurotrophins, and support the role of GSK3 as an important convergence point for these survival promoting factors in granule neurons.

  11. P2X7 receptor regulates osteoclast function and bone loss in a mouse model of osteoporosis.

    Science.gov (United States)

    Wang, Ning; Agrawal, Ankita; Jørgensen, Niklas Rye; Gartland, Alison

    2018-02-22

    Post-menopausal osteoporosis is a condition that affects millions worldwide and places a huge socio-economic burden on society. Previous research has shown an association of loss of function SNPs in the gene for the purinergic receptor P2X7R with low bone mineral density, increased rates of bone loss and vertebral fractures in post-menopausal women. In this study we use a mouse model of oestrogen deficiency-induced bone loss and the BALB/cJ P2X7R -/- to show that absence of the P2X7R resulted in increased bone loss. Osteoclast precursors were isolated from both BALB/cJ P2X7R -/- and BALB/cJ P2X7R +/+ mice and then cultured in vitro to form mature resorbing osteoclasts. The BALB/cJ P2X7R -/- derived precursors generated slightly more osteoclasts but with a significant reduction in the amount of resorption per osteoclast. Furthermore, when using modified culture conditions osteoclast activity was additionally increased in the absence of the P2X7R suggest that P2X7R may regulate the lifespan and activity of osteoclasts. Finally using mechanical loading as an anabolic stimulus for bone formation, we demonstrated that the increased oestrogen-deficient bone loss could be rescued, even in the absence of P2X7R. This study paves the way for clinical intervention for women with post-menopausal osteoporosis and P2XR7 loss of function polymorphisms.

  12. Lack of a Functioning P2X7 Receptor Leads to Increased Susceptibility to Toxoplasmic Ileitis.

    Directory of Open Access Journals (Sweden)

    Catherine M Miller

    Full Text Available Oral infection of C57BL/6J mice with the protozoan parasite Toxoplasma gondii leads to a lethal inflammatory ileitis.Mice lacking the purinergic receptor P2X7R are acutely susceptible to toxoplasmic ileitis, losing significantly more weight than C57BL/6J mice and exhibiting much greater intestinal inflammatory pathology in response to infection with only 10 cysts of T. gondii. This susceptibility is not dependent on the ability of P2X7R-deficient mice to control the parasite, which they accomplish just as efficiently as C57BL/6J mice. Rather, susceptibility is associated with elevated ileal concentrations of pro-inflammatory cytokines, reactive nitrogen intermediates and altered regulation of elements of NFκB activation in P2X7R-deficient mice.Our data support the thesis that P2X7R, a well-documented activator of pro-inflammatory cytokine production, also plays an important role in the regulation of intestinal inflammation.

  13. P2X7 receptor drives Th1 cell differentiation and controls the follicular helper T cell population to protect against Plasmodium chabaudi malaria.

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    Érika Machado de Salles

    2017-08-01

    Full Text Available A complete understanding of the mechanisms underlying the acquisition of protective immunity is crucial to improve vaccine strategies to eradicate malaria. However, it is still unclear whether recognition of damage signals influences the immune response to Plasmodium infection. Adenosine triphosphate (ATP accumulates in infected erythrocytes and is released into the extracellular milieu through ion channels in the erythrocyte membrane or upon erythrocyte rupture. The P2X7 receptor senses extracellular ATP and induces CD4 T cell activation and death. Here we show that P2X7 receptor promotes T helper 1 (Th1 cell differentiation to the detriment of follicular T helper (Tfh cells during blood-stage Plasmodium chabaudi malaria. The P2X7 receptor was activated in CD4 T cells following the rupture of infected erythrocytes and these cells became highly responsive to ATP during acute infection. Moreover, mice lacking the P2X7 receptor had increased susceptibility to infection, which correlated with impaired Th1 cell differentiation. Accordingly, IL-2 and IFNγ secretion, as well as T-bet expression, critically depended on P2X7 signaling in CD4 T cells. Additionally, P2X7 receptor controlled the splenic Tfh cell population in infected mice by promoting apoptotic-like cell death. Finally, the P2X7 receptor was required to generate a balanced Th1/Tfh cell population with an improved ability to transfer parasite protection to CD4-deficient mice. This study provides a new insight into malaria immunology by showing the importance of P2X7 receptor in controlling the fine-tuning between Th1 and Tfh cell differentiation during P. chabaudi infection and thus in disease outcome.

  14. Neuropharmacology of Purinergic Receptors in Human Submucous Plexus: Involvement of P2X1, P2X2, P2X3 Channels, P2Y and A3 Metabotropic Receptors in Neurotransmission

    Science.gov (United States)

    Liñán-Rico, A.; Wunderlich, JE.; Enneking, JT.; Tso, DR.; Grants, I.; Williams, KC.; Otey, A.; Michel, K.; Schemann, M.; Needleman, B.; Harzman, A.; Christofi, FL.

    2015-01-01

    Rationale The role of purinergic signaling in the human ENS is not well understood. We sought to further characterize the neuropharmacology of purinergic receptors in human ENS and test the hypothesis that endogenous purines are critical regulators of neurotransmission. Experimental Approach LSCM-Fluo-4-(Ca2+)-imaging of postsynaptic Ca2+ transients (PSCaTs) was used as a reporter of neural activity. Synaptic transmission was evoked by fiber tract electrical stimulation in human SMP surgical preparations. Pharmacological analysis of purinergic signaling was done in 1,556 neurons from 234 separate ganglia 107 patients; immunochemical labeling for P2XRs of neurons in ganglia from 19 patients. Real-time MSORT (Di-8-ANEPPS) imaging was used to test effects of adenosine on fast excitatory synaptic potentials (fEPSPs). Results Synaptic transmission is sensitive to pharmacological manipulations that alter accumulation of extracellular purines. Apyrase blocks PSCaTs in a majority of neurons. An ecto-NTPDase-inhibitor 6-N,N-diethyl-D-β,γ-dibromomethyleneATP or adenosine deaminase augments PSCaTs. Blockade of reuptake/deamination of eADO inhibits PSCaTs. Adenosine inhibits fEPSPs and PSCaTs (IC50=25μM), sensitive to MRS1220-antagonism (A3AR). A P2Y agonist ADPβS inhibits PSCaTs (IC50=111nM) in neurons without stimulatory ADPβS responses (EC50=960nM). ATP or a P2X1,2,2/3 (α,β-MeATP) agonist evokes fast, slow, biphasic Ca2+ transients or Ca2+ oscillations (EC50=400μM). PSCaTs are sensitive to P2X1 antagonist NF279. Low (20nM) or high (5μM) concentrations of P2X antagonist TNP-ATP block PSCaTs in different neurons; proportions of neurons with P2XR-ir follow the order P2X2>P2X1≫P2X3; P2X1+ P2X2 and P2X3+P2X2 are co-localized. RT-PCR identified mRNA-transcripts for P2X1-7,P2Y1,2,12-14R. Responsive neurons were also identified by HuC/D-ir. Conclusions Purines are critical regulators of neurotransmission in the human enteric nervous system. Purinergic signaling involves

  15. Structural and Molecular Modeling Features of P2X Receptors

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    Luiz Anastacio Alves

    2014-03-01

    Full Text Available Currently, adenosine 5'-triphosphate (ATP is recognized as the extracellular messenger that acts through P2 receptors. P2 receptors are divided into two subtypes: P2Y metabotropic receptors and P2X ionotropic receptors, both of which are found in virtually all mammalian cell types studied. Due to the difficulty in studying membrane protein structures by X-ray crystallography or NMR techniques, there is little information about these structures available in the literature. Two structures of the P2X4 receptor in truncated form have been solved by crystallography. Molecular modeling has proven to be an excellent tool for studying ionotropic receptors. Recently, modeling studies carried out on P2X receptors have advanced our knowledge of the P2X receptor structure-function relationships. This review presents a brief history of ion channel structural studies and shows how modeling approaches can be used to address relevant questions about P2X receptors.

  16. Antidepressants inhibit P2X4 receptor function: a possible involvement in neuropathic pain relief

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    Tozaki-Saitoh Hidetoshi

    2009-04-01

    Full Text Available Abstract Background Neuropathic pain is characterized by pain hypersensitivity to innocuous stimuli (tactile allodynia that is nearly always resistant to known treatments such as non-steroidal anti-inflammatory drugs or even opioids. It has been reported that some antidepressants are effective for treating neuropathic pain. However, the underlying molecular mechanisms are not well understood. We have recently demonstrated that blocking P2X4 receptors in the spinal cord reverses tactile allodynia after peripheral nerve injury in rats, implying that P2X4 receptors are a key molecule in neuropathic pain. We investigated a possible role of antidepressants as inhibitors of P2X4 receptors and analysed their analgesic mechanism using an animal model of neuropathic pain. Results Antidepressants strongly inhibited ATP-mediated Ca2+ responses in P2X4 receptor-expressing 1321N1 cells, which are known to have no endogenous ATP receptors. Paroxetine exhibited the most powerful inhibition of calcium influx via rat and human P2X4 receptors, with IC50 values of 2.45 μM and 1.87 μM, respectively. Intrathecal administration of paroxetine produced a striking antiallodynic effect in an animal model of neuropathic pain. Co-administration of WAY100635, ketanserin or ondansetron with paroxetine induced no significant change in the antiallodynic effect of paroxetine. Furthermore, the antiallodynic effect of paroxetine was observed even in rats that had received intrathecal pretreatment with 5,7-dihydroxytryptamine, which dramatically depletes spinal 5-hydroxytryptamine. Conclusion These results suggest that paroxetine acts as a potent analgesic in the spinal cord via a mechanism independent of its inhibitory effect on serotonin transporters. Powerful inhibition on P2X4 receptors may underlie the analgesic effect of paroxetine, and it is possible that some antidepressants clinically used in patients with neuropathic pain show antiallodynic effects, at least in part

  17. Circadian ATP Release in Organotypic Cultures of the Rat Suprachiasmatic Nucleus Is Dependent on P2X7 and P2Y Receptors

    Czech Academy of Sciences Publication Activity Database

    Svobodová, Irena; Bhattacharya, Anirban; Ivetic, Milorad; Bendová, Z.; Zemková, Hana

    2018-01-01

    Roč. 9, Mar 6 (2018), č. článku 192. ISSN 1663-9812 R&D Projects: GA ČR(CZ) GA16-12695S; GA ČR(CZ) GBP304/12/G069; GA MŠk(CZ) LQ1604; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:67985823 Keywords : suprachiasmatic nucleus * organotypic cultures * astrocytes * P2X7 receptor * P2Y1 receptor * P2Y2 receptor * pannexin-1 hemichannel * ATP release Subject RIV: FH - Neurology OBOR OECD: Neurosciences (including psychophysiology Impact factor: 4.400, year: 2016

  18. P2X7 on mouse T cells: one channel, many functions

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    Björn eRissiek

    2015-05-01

    Full Text Available The P2X7 receptor is an adenosine triphosphate (ATP-gated cation channel that is expressed by several cells of the immune system. P2X7 is best known for its proinflammatory role in promoting inflammasome formation and release of mature IL-1β by innate immune cells. Mounting evidence indicates that P2X7 is also an important regulatory receptor of murine and human T cell functions. Murine T cells express a sensitive splice variant of P2X7 that can be activated either by non-covalent binding of ATP or, in the presence of nicotinamide adenine dinucleotide (NAD+, by its covalent ADP-ribosylation catalyzed by the ecto-ADP-ribosyltransferase ARTC2.2. Prolonged activation of P2X7 by either one of these pathways triggers the induction of T cell death. Conversely, lower concentrations of ATP can activate P2X7 to enhance T cell proliferation and production of IL-2. In this review we will highlight the molecular and cellular consequences of P2X7 activation on mouse T cells and its versatile role in T cell homeostasis and activation. Further, we will discuss important differences in the function of P2X7 on human and murine T cells.

  19. P2X(7 receptor in the kidneys of diabetic rats submitted to aerobic training or to N-acetylcysteine supplementation [corrected].

    Directory of Open Access Journals (Sweden)

    Adelson M Rodrigues

    Full Text Available Previous studies in our laboratory showed that N-acetylcysteine supplementation or aerobic training reduced oxidative stress and the progression of diabetic nephropathy in rats. The P2X(7 receptor is up-regulated in pathological conditions, such as diabetes mellitus. This up-regulation is related to oxidative stress and induces tissue apoptosis or necrosis. The aim of the present study is to assess the role of P2X(7 receptor in the kidneys of diabetic rats submitted to aerobic training or N-acetylcysteine supplementation. Diabetes was induced in male Wistar rats by streptozotocin (60 mg/kg, i.v. and the training was done on a treadmill; N-acetylcysteine was given in the drinking water (600 mg/L. By confocal microscopy, as compared to control, the kidneys of diabetic rats showed increased P2 × 7 receptor expression and a higher activation in response to 2'(3'-O-(4-benzoylbenzoyl adenosine5'-triphosphate (specific agonist and adenosine triphosphate (nonspecific agonist (all p<0.05. All these alterations were reduced in diabetic rats treated with N-acetylcysteine, exercise or both. We also observed measured proteinuria and albuminuria (early marker of diabetic nephropathy in DM groups. Lipoperoxidation was strongly correlated with P2X(7 receptor expression, which was also correlated to NO•, thus associating this receptor to oxidative stress and kidney lesion. We suggest that P2X(7 receptor inhibition associated with the maintenance of redox homeostasis could be useful as coadjuvant treatment to delay the progression of diabetic nephropathy.

  20. P2X(7) receptor in the kidneys of diabetic rats submitted to aerobic training or to N-acetylcysteine supplementation [corrected].

    Science.gov (United States)

    Rodrigues, Adelson M; Bergamaschi, Cassia T; Fernandes, Maria Jose S; Paredes-Gamero, Edgar J; Buri, Marcus V; Curi, Marcus V; Ferreira, Alice T; Araujo, Sergio R R; Punaro, Giovana R; Maciel, Fabiane R; Nogueira, Guilherme B; Higa, Elisa M S

    2014-01-01

    Previous studies in our laboratory showed that N-acetylcysteine supplementation or aerobic training reduced oxidative stress and the progression of diabetic nephropathy in rats. The P2X(7 receptor is up-regulated in pathological conditions, such as diabetes mellitus. This up-regulation is related to oxidative stress and induces tissue apoptosis or necrosis. The aim of the present study is to assess the role of P2X(7) receptor in the kidneys of diabetic rats submitted to aerobic training or N-acetylcysteine supplementation. Diabetes was induced in male Wistar rats by streptozotocin (60 mg/kg, i.v.) and the training was done on a treadmill; N-acetylcysteine was given in the drinking water (600 mg/L). By confocal microscopy, as compared to control, the kidneys of diabetic rats showed increased P2 × 7 receptor expression and a higher activation in response to 2'(3')-O-(4-benzoylbenzoyl) adenosine5'-triphosphate (specific agonist) and adenosine triphosphate (nonspecific agonist) (all p<0.05). All these alterations were reduced in diabetic rats treated with N-acetylcysteine, exercise or both. We also observed measured proteinuria and albuminuria (early marker of diabetic nephropathy) in DM groups. Lipoperoxidation was strongly correlated with P2X(7) receptor expression, which was also correlated to NO•, thus associating this receptor to oxidative stress and kidney lesion. We suggest that P2X(7) receptor inhibition associated with the maintenance of redox homeostasis could be useful as coadjuvant treatment to delay the progression of diabetic nephropathy.

  1. Submucosal neurons and enteric glial cells expressing the P2X7 receptor in rat experimental colitis.

    Science.gov (United States)

    da Silva, Marcos Vinícius; Marosti, Aline Rosa; Mendes, Cristina Eusébio; Palombit, Kelly; Castelucci, Patricia

    2017-06-01

    The aim of this study was to evaluate the effect of ulcerative colitis on the submucosal neurons and glial cells of the submucosal ganglia of rats. 2,4,6-Trinitrobenzene sulfonic acid (TNBS; colitis group) was administered in the colon to induce ulcerative colitis, and distal colons were collected after 24h. The colitis rats were compared with those in the sham and control groups. Double labelling of the P2X7 receptor with calbindin (marker for intrinsic primary afferent neurons, IPANs, submucosal plexus), calretinin (marker for secretory and vasodilator neurons of the submucosal plexus), HuC/D and S100β was performed in the submucosal plexus. The density (neurons per area) of submucosal neurons positive for the P2X7 receptor, calbindin, calretinin and HuC/D decreased by 21%, 34%, 8.2% and 28%, respectively, in the treated group. In addition, the density of enteric glial cells in the submucosal plexus decreased by 33%. The profile areas of calbindin-immunoreactive neurons decreased by 25%. Histological analysis revealed increased lamina propria and decreased collagen in the colitis group. This study demonstrated that ulcerative colitis affected secretory and vasodilatory neurons, IPANs and enteric glia of the submucosal plexus expressing the P2X7 receptor. Copyright © 2017 Elsevier GmbH. All rights reserved.

  2. Knocking out P2X receptors reduces transmitter secretion in taste buds

    Science.gov (United States)

    Huang, Yijen A.; Stone, Leslie M.; Pereira, Elizabeth; Yang, Ruibiao; Kinnamon, John C.; Dvoryanchikov, Gennady; Chaudhari, Nirupa; Finger, Thomas E.; Kinnamon, Sue C.; Roper, Stephen D.

    2011-01-01

    In response to gustatory stimulation, taste bud cells release a transmitter, ATP, that activates P2X2 and P2X3 receptors on gustatory afferent fibers. Taste behavior and gustatory neural responses are largely abolished in mice lacking P2X2 and P2X3 receptors (P2X2 and P2X3 double knockout, or “DKO” mice). The assumption has been that eliminating P2X2 and P2X3 receptors only removes postsynaptic targets but that transmitter secretion in mice is normal. Using functional imaging, ATP biosensor cells, and a cell-free assay for ATP, we tested this assumption. Surprisingly, although gustatory stimulation mobilizes Ca2+ in taste Receptor (Type II) cells from DKO mice, as from wild type (WT) mice, taste cells from DKO mice fail to release ATP when stimulated with tastants. ATP release could be elicited by depolarizing DKO Receptor cells with KCl, suggesting that ATP-release machinery remains functional in DKO taste buds. To explore the difference in ATP release across genotypes, we employed reverse transcriptase (RT)-PCR, immunostaining, and histochemistry for key proteins underlying ATP secretion and degradation: Pannexin1, TRPM5, and NTPDase2 (ecto-ATPase) are indistinguishable between WT and DKO mice. The ultrastructure of contacts between taste cells and nerve fibers is also normal in the DKO mice. Finally, quantitative RT-PCR show that P2X4 and P2X7, potential modulators of ATP secretion, are similarly expressed in taste buds in WT and DKO taste buds. Importantly, we find that P2X2 is expressed in WT taste buds and appears to function as an autocrine, positive feedback signal to amplify taste-evoked ATP secretion. PMID:21940456

  3. Knocking out P2X receptors reduces transmitter secretion in taste buds.

    Science.gov (United States)

    Huang, Yijen A; Stone, Leslie M; Pereira, Elizabeth; Yang, Ruibiao; Kinnamon, John C; Dvoryanchikov, Gennady; Chaudhari, Nirupa; Finger, Thomas E; Kinnamon, Sue C; Roper, Stephen D

    2011-09-21

    In response to gustatory stimulation, taste bud cells release a transmitter, ATP, that activates P2X2 and P2X3 receptors on gustatory afferent fibers. Taste behavior and gustatory neural responses are largely abolished in mice lacking P2X2 and P2X3 receptors [P2X2 and P2X3 double knock-out (DKO) mice]. The assumption has been that eliminating P2X2 and P2X3 receptors only removes postsynaptic targets but that transmitter secretion in mice is normal. Using functional imaging, ATP biosensor cells, and a cell-free assay for ATP, we tested this assumption. Surprisingly, although gustatory stimulation mobilizes Ca(2+) in taste Receptor (Type II) cells from DKO mice, as from wild-type (WT) mice, taste cells from DKO mice fail to release ATP when stimulated with tastants. ATP release could be elicited by depolarizing DKO Receptor cells with KCl, suggesting that ATP-release machinery remains functional in DKO taste buds. To explore the difference in ATP release across genotypes, we used reverse transcriptase (RT)-PCR, immunostaining, and histochemistry for key proteins underlying ATP secretion and degradation: Pannexin1, TRPM5, and NTPDase2 (ecto-ATPase) are indistinguishable between WT and DKO mice. The ultrastructure of contacts between taste cells and nerve fibers is also normal in the DKO mice. Finally, quantitative RT-PCR show that P2X4 and P2X7, potential modulators of ATP secretion, are similarly expressed in taste buds in WT and DKO taste buds. Importantly, we find that P2X2 is expressed in WT taste buds and appears to function as an autocrine, positive feedback signal to amplify taste-evoked ATP secretion.

  4. The purinergic P2X7 ion channel receptor — a ‘repair’ receptor in bone

    DEFF Research Database (Denmark)

    Jørgensen, Niklas Rye

    2018-01-01

    A strong skeleton relies on adaptation to varying physical demands and on maintenance of the bone tissue in order to avoid accumulation of micro-damage. In bone, the purinergic P2X7 ion channel receptor is expressed on both cells of the stromal lineage such as the bone forming osteoblasts...... and the mechano-sensing osteocytes and on cells belonging to the immune-related monocyte–macrophage lineage, the bone resorbing osteoclasts. Recent studies have demonstrated that the receptor plays important roles in the anabolic responses to mechanical loading on bone and, together with the pannexin1 hemi......-channel, in the process of initiating bone remodeling in response to micro-damage. Thus, the receptor is crucial in skeletal mechano-transduction and in the continuous repair process. However, under pathophysiological conditions such as diabetes with high glucose concentrations or glucocorticoid-treatment the receptor...

  5. Postsynaptic P2X3-containing receptors in gustatory nerve fibres mediate responses to all taste qualities in mice.

    Science.gov (United States)

    Vandenbeuch, Aurelie; Larson, Eric D; Anderson, Catherine B; Smith, Steven A; Ford, Anthony P; Finger, Thomas E; Kinnamon, Sue C

    2015-03-01

    Taste buds release ATP to activate ionotropic purinoceptors composed of P2X2 and P2X3 subunits, present on the taste nerves. Mice with genetic deletion of P2X2 and P2X3 receptors (double knockout mice) lack responses to all taste stimuli presumably due to the absence of ATP-gated receptors on the afferent nerves. Recent experiments on the double knockout mice showed, however, that their taste buds fail to release ATP, suggesting the possibility of pleiotropic deficits in these global knockouts. To test further the role of postsynaptic P2X receptors in afferent signalling, we used AF-353, a selective antagonist of P2X3-containing receptors to inhibit the receptors acutely during taste nerve recording and behaviour. The specificity of AF-353 for P2X3-containing receptors was tested by recording Ca(2+) transients to exogenously applied ATP in fura-2 loaded isolated geniculate ganglion neurons from wild-type and P2X3 knockout mice. ATP responses were completely inhibited by 10 μm or 100 μm AF-353, but neither concentration blocked responses in P2X3 single knockout mice wherein the ganglion cells express only P2X2-containing receptors. Furthermore, AF-353 had no effect on taste-evoked ATP release from taste buds. In wild-type mice, i.p. injection of AF-353 or simple application of the drug directly to the tongue, inhibited taste nerve responses to all taste qualities in a dose-dependent fashion. A brief access behavioural assay confirmed the electrophysiological results and showed that preference for a synthetic sweetener, SC-45647, was abolished following i.p. injection of AF-353. These data indicate that activation of P2X3-containing receptors is required for transmission of all taste qualities. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

  6. Inhibition of P2X7 receptor ameliorates transient global cerebral ischemia/reperfusion injury via modulating inflammatory responses in the rat hippocampus

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    Chu Ketan

    2012-04-01

    Full Text Available Abstract Background Neuroinflammation plays an important role in cerebral ischemia/reperfusion (I/R injury. The P2X7 receptor (P2X7R has been reported to be involved in the inflammatory response of many central nervous system diseases. However, the role of P2X7Rs in transient global cerebral I/R injury remains unclear. The purpose of this study is to determine the effects of inhibiting the P2X7R in a rat model of transient global cerebral I/R injury, and then to explore the association between the P2X7R and neuroinflammation after transient global cerebral I/R injury. Methods Immediately after infusion with the P2X7R antagonists Brilliant blue G (BBG, adenosine 5′-triphosphate-2′,3′-dialdehyde (OxATP or A-438079, 20 minutes of transient global cerebral I/R was induced using the four-vessel occlusion (4-VO method in rats. Survival rate was calculated, neuronal death in the hippocampal CA1 region was observed using H & E staining, and DNA cleavage was observed by deoxynucleotidyl transferase-mediated UTP nick end labeling TUNEL. In addition, behavioral deficits were measured using the Morris water maze, and RT-PCR and immunohistochemical staining were performed to measure the expression of IL-1β, TNF-α and IL-6, and to identify activated microglia and astrocytes. Results The P2X7R antagonists protected against transient global cerebral I/R injury in a dosage-dependent manner. A high dosage of BBG (10 μg and A-0438079 (3 μg, and a low dosage of OxATP (1 μg significantly increased survival rates, reduced I/R-induced learning memory deficit, and reduced I/R-induced neuronal death, DNA cleavage, and glial activation and inflammatory cytokine overexpression in the hippocampus. Conclusions Our study indicates that inhibiting P2X7Rs protects against transient global cerebral I/R injury by reducing the I/R-induced inflammatory response, which suggests inhibition of P2X7Rs may be a promising therapeutic strategy for clinical treatment of

  7. Medicinal chemistry of adenosine, P2Y and P2X receptors.

    Science.gov (United States)

    Jacobson, Kenneth A; Müller, Christa E

    2016-05-01

    Pharmacological tool compounds are now available to define action at the adenosine (ARs), P2Y and P2X receptors. We present a selection of the most commonly used agents to study purines in the nervous system. Some of these compounds, including A1 and A3 AR agonists, P2Y1R and P2Y12R antagonists, and P2X3, P2X4 and P2X7 antagonists, are potentially of clinical use in treatment of disorders of the nervous system, such as chronic pain, neurodegeneration and brain injury. Agonists of the A2AAR and P2Y2R are already used clinically, P2Y12R antagonists are widely used antithrombotics and an antagonist of the A2AAR is approved in Japan for treating Parkinson's disease. The selectivity defined for some of the previously introduced compounds has been revised with updated pharmacological characterization, for example, various AR agonists and antagonists were deemed A1AR or A3AR selective based on human data, but species differences indicated a reduction in selectivity ratios in other species. Also, many of the P2R ligands still lack bioavailability due to charged groups or hydrolytic (either enzymatic or chemical) instability. X-ray crystallographic structures of AR and P2YRs have shifted the mode of ligand discovery to structure-based approaches rather than previous empirical approaches. The X-ray structures can be utilized either for in silico screening of chemically diverse libraries for the discovery of novel ligands or for enhancement of the properties of known ligands by chemical modification. Although X-ray structures of the zebrafish P2X4R have been reported, there is scant structural information about ligand recognition in these trimeric ion channels. In summary, there are definitive, selective agonists and antagonists for all of the ARs and some of the P2YRs; while the pharmacochemistry of P2XRs is still in nascent stages. The therapeutic potential of selectively modulating these receptors is continuing to gain interest in such fields as cancer, inflammation, pain

  8. Basolateral P2X receptors mediate inhibition of NaCl transport in mouse medullary thick ascending limb (mTAL)

    DEFF Research Database (Denmark)

    Marques, Rita D; de Bruijn, Pauline I.A.; Sørensen, Mads Vaarby

    2012-01-01

    Extracellular nucleotides regulate epithelial transport via luminal and basolateral P2 receptors. Renal epithelia express multiple P2 receptors, which mediate significant inhibition of solute absorption. Recently, we identified several P2 receptors in the medullary thick ascending limb (m...

  9. Functional expression of P2X family receptors in macrophages is affected by microenvironment in mouse T cell acute lymphoblastic leukemia

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shayan; Feng, Wenli; Yang, Xiao; Yang, Wanzhu; Ru, Yongxin; Liao, Jinfeng; Wang, Lina; Lin, Yongmin; Ren, Qian [State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300020 (China); Zheng, Guoguang, E-mail: zhengggtjchn@aliyun.com [State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300020 (China); Center for Stem Cell Medicine, Chinese Academy of Medical Sciences, Beijing 100730 (China)

    2014-04-18

    Highlights: • We study the impact of leukemic microenvironment on P2X family receptors in Mφs. • Bone marrow and spleen Mφs are studied in Notch1-induced mouse leukemia model. • Increased expression of P2X7R is found in Mφs during the development of leukemia. • Elevated P2X7R-mediated calcium response is found in Mφs at late stage of leukemia. • More apoptotic Mφs are found in bone marrow and spleen at late stage of leukemia. - Abstract: Nucleotides are important players in intercellular signaling communication network. P2X family receptors (P2XRs) are ATP-gated plasma membrane ion channels with diverse biological functions. Macrophages are important components in the microenvironment of hematopoiesis participating in both physiological and pathological processes. However, the role of P2XRs in macrophages in leukemia has not been established. Here we investigated expression pattern and functions of P2XRs in macrophages from bone marrow (BM) and spleen of Notch1-induced T-ALL mice. Real-time PCR showed that P2XRs except P2X5R were expressed in BM and spleen macrophages. Furthermore, with the development of leukemia, the expression of P2X7R increased in both BM and spleen macrophages whereas expression of P2X1R increased in spleen macrophages. Live cell imaging recoding the Ca{sup 2+} response demonstrated that P2X7R expressed in macrophages was functional. TUNEL and electron microscopy analysis found that apoptotic macrophages were frequently observed in BM and spleen at late stage of leukemia, which was partly contributed by the activation of overexpressed P2X7R. Our results suggested that the intercellular communication mediated by nucleotides might orchestrate in the pathological process of leukemia and could be a potential target for the treatment of leukemia.

  10. Functional expression of P2X family receptors in macrophages is affected by microenvironment in mouse T cell acute lymphoblastic leukemia

    International Nuclear Information System (INIS)

    Chen, Shayan; Feng, Wenli; Yang, Xiao; Yang, Wanzhu; Ru, Yongxin; Liao, Jinfeng; Wang, Lina; Lin, Yongmin; Ren, Qian; Zheng, Guoguang

    2014-01-01

    Highlights: • We study the impact of leukemic microenvironment on P2X family receptors in Mφs. • Bone marrow and spleen Mφs are studied in Notch1-induced mouse leukemia model. • Increased expression of P2X7R is found in Mφs during the development of leukemia. • Elevated P2X7R-mediated calcium response is found in Mφs at late stage of leukemia. • More apoptotic Mφs are found in bone marrow and spleen at late stage of leukemia. - Abstract: Nucleotides are important players in intercellular signaling communication network. P2X family receptors (P2XRs) are ATP-gated plasma membrane ion channels with diverse biological functions. Macrophages are important components in the microenvironment of hematopoiesis participating in both physiological and pathological processes. However, the role of P2XRs in macrophages in leukemia has not been established. Here we investigated expression pattern and functions of P2XRs in macrophages from bone marrow (BM) and spleen of Notch1-induced T-ALL mice. Real-time PCR showed that P2XRs except P2X5R were expressed in BM and spleen macrophages. Furthermore, with the development of leukemia, the expression of P2X7R increased in both BM and spleen macrophages whereas expression of P2X1R increased in spleen macrophages. Live cell imaging recoding the Ca 2+ response demonstrated that P2X7R expressed in macrophages was functional. TUNEL and electron microscopy analysis found that apoptotic macrophages were frequently observed in BM and spleen at late stage of leukemia, which was partly contributed by the activation of overexpressed P2X7R. Our results suggested that the intercellular communication mediated by nucleotides might orchestrate in the pathological process of leukemia and could be a potential target for the treatment of leukemia

  11. Targeting of the P2X7 receptor in pancreatic cancer and stellate cells

    DEFF Research Database (Denmark)

    Giannuzzo, Andrea; Saccomano, Mara; Napp, Joanna

    2016-01-01

    of PDAC. In the in vitro studies we show that human PDAC cells with luciferase gene (PancTu-1 Luc cells) express high levels of P2X7R protein. Allosteric P2X7R antagonist AZ10606120 inhibited cell proliferation in basal conditions, indicating that P2X7R was tonically active. Extracellular ATP and Bz......ATP, to which the P2X7R is more sensitive, further affected cell survival and confirmed complex functionality of P2X7R. PancTu-1 Luc migration and invasion was reduced by AZ10606120, and it was stimulated by PSCs, but not by PSCs from P2X7(-/-) animals. PancTu-1 Luc cells were orthotopically transplanted...

  12. Role of P2X7 on steroid synthesis in murine luteal cells

    Directory of Open Access Journals (Sweden)

    Chunping Zhang

    2016-03-01

    Full Text Available The extracellular adenosine triphosphate (ATP regulates different cellular functions through activating purinergic receptors as a signalling molecule or neurotransmitter. P2X7 is highly expressed in murine small luteal cells. In this study, murine luteal cells were cultured in vitro and treated with P2X7 agonists – ATP and 2′(3′-O-(4-benzoyl-benzoyl-adenosine 50-triphosphate (BzATP and with P2X7 antagonist – brilliant blue G (BBG. We found that ATP and BzATP increased the production of progesterone and had no influence on the production of estradiol. BBG reversed the effect of BzATP and ATP. Further studies demonstrated that ATP and BzATP promoted the expression of CYP11A. These results revealed that P2X7 receptor activation is involved in the steroid synthesis in corpus luteum.

  13. DESENSITIZATION PROPERTIES OF P2X3 RECEPTORS SHAPING PAIN SIGNALLING

    Directory of Open Access Journals (Sweden)

    Rashid eGiniatullin

    2013-12-01

    Full Text Available ATP-gated P2X3 receptors are mostly expressed by nociceptive sensory neurons and participate in transduction of pain signals. P2X3 receptors show a combination of fast desensitization onset and slow recovery. Moreover, even low nanomolar agonist concentrations unable to evoke a response, can induce desensitization via a phenomenon called ‘high affinity desensitization’. We have also observed that recovery from desensitization is agonist-specific and can range from seconds to minutes. The recovery process displays unusually high temperature dependence. Likewise, recycling of P2X3 receptors in peri-membrane regions shows unexpectedly large temperature sensitivity. By applying kinetic modeling, we have previously shown that desensitization characteristics of P2X3 receptor are best explained with a cyclic model of receptor operation involving three agonist molecules binding a single receptor and that desensitization is primarily developing from the open receptor state. Mutagenesis experiments suggested that desensitization depends on a certain conformation of the ATP binding pocket and on the structure of the transmembrane domains forming the ion pore. Further molecular determinants of desensitization have been identified by mutating the intracellular N- and C-termini of P2X3 receptor. Unlike other P2X receptors, the P2X3 subtype is facilitated by extracellular calcium that acts via specific sites in the ectodomain neighboring the ATP binding pocket. Thus, substitution of serine275 in this region (called ‘left flipper’ converts the natural facilitation induced by extracellular calcium to receptor inhibition. Given such their strategic location in nociceptive neurons and unique desensitization properties, P2X3 receptors represent an attractive target for development of new analgesic drugs via promotion of desensitization aimed at suppressing chronic pain.

  14. Loss of Function of P2X7 Receptor Scavenger Activity in Aging Mice: A Novel Model for Investigating the Early Pathogenesis of Age-Related Macular Degeneration.

    Science.gov (United States)

    Vessey, Kirstan A; Gu, Ben J; Jobling, Andrew I; Phipps, Joanna A; Greferath, Ursula; Tran, Mai X; Dixon, Michael A; Baird, Paul N; Guymer, Robyn H; Wiley, James S; Fletcher, Erica L

    2017-08-01

    Age-related macular degeneration (AMD) is a leading cause of irreversible, severe vision loss in Western countries. Recently, we identified a novel pathway involving P2X7 receptor scavenger function expressed on ocular immune cells as a risk factor for advanced AMD. In this study, we investigate the effect of loss of P2X7 receptor function on retinal structure and function during aging. P2X7-null and wild-type C57bl6J mice were investigated at 4, 12, and 18 months of age for macrophage phagocytosis activity, ocular histological changes, and retinal function. Phagocytosis activity of blood-borne macrophages decreased with age at 18 months in the wild-type mouse. Lack of P2X7 receptor function reduced phagocytosis at all ages compared to wild-type mice. At 12 months of age, P2X7-null mice had thickening of Bruchs membrane and retinal pigment epithelium dysfunction. By 18 months of age, P2X7-null mice displayed phenotypic characteristics consistent with early AMD, including Bruchs membrane thickening, retinal pigment epithelium cell loss, retinal functional deficits, and signs of subretinal inflammation. Our present study shows that loss of function of the P2X7 receptor in mice induces retinal changes representing characteristics of early AMD, providing a valuable model for investigating the role of scavenger receptor function and the immune system in the development of this age-related disease. Copyright © 2017 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  15. P2X purinoceptors as a link between hyperexcitability and neuroinflammation in status epilepticus.

    Science.gov (United States)

    Henshall, David C; Engel, Tobias

    2015-08-01

    There remains a need for more efficacious treatments for status epilepticus. Prolonged seizures result in the release of ATP from cells which activates the P2 class of ionotropic and metabotropic purinoceptors. The P2X receptors gate depolarizing sodium and calcium entry and are expressed by both neurons and glia throughout the brain, and a number of subtypes are upregulated after status epilepticus. Recent studies have explored the in vivo effects of targeting ATP-gated P2X receptors in preclinical models of status epilepticus, with particular focus on the P2X7 receptor (P2X7R). The P2X7R mediates microglial activation and the release of the proepileptogenic inflammatory cytokine interleukin 1β. The receptor may also directly modulate neurotransmission and gliotransmission and promote the recruitment of immune cells into brain parenchyma. Data from our group and collaborators show that status epilepticus produced by intraamygdala microinjection of kainic acid increases P2X7R expression in the hippocampus and neocortex of mice. Antagonism of the P2X7R in the model reduced seizure severity, microglial activation and interleukin 1β release, and neuronal injury. Coadministration of a P2X7R antagonist with a benzodiazepine also provided seizure suppression in a model of drug-refractory status epilepticus when either treatment alone was minimally effective. More recently, we showed that status epilepticus in immature rats is also reduced by P2X7R antagonism. Together, these findings suggest that P2X receptors may be novel targets for seizure control and interruption of neuroinflammation after status epilepticus. This article is part of a Special Issue entitled "Status Epilepticus". Copyright © 2015 Elsevier Inc. All rights reserved.

  16. P2X7 Receptor Expression in Peripheral Blood Monocytes Is Correlated With Plasma C-Reactive Protein and Cytokine Levels in Patients With Type 2 Diabetes Mellitus: a Preliminary Report.

    Science.gov (United States)

    Wu, Hong; Nie, Yijun; Xiong, Huangui; Liu, Shuangmei; Li, Guilin; Huang, An; Guo, Lili; Wang, Shouyu; Xue, Yun; Wu, Bing; Peng, Lichao; Song, Miaomiao; Li, Guodong; Liang, Shangdong

    2015-12-01

    Chronic inflammation plays a major role in development of type 2 diabetes mellitus (T2DM). C-reactive protein (CRP) and inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β) are directly involved in the occurrence of insulin resistance. Increased extracellular ATP levels can amplify the inflammatory response in vivo via the P2X7 receptor. The present study aimed to assess the relationship between P2X7 receptor expression in human peripheral blood monocytes and plasma levels of TNF-α, IL-1β, and CRP in T2DM patients. The results showed the association of increased P2X7 receptor expression of monocytes with high serum CRP, TNF-α, and IL-1β levels. TNF-α and IL-1β levels were lowest in healthy subjects; in T2DM patients, these inflammatory markers were less abundant in individuals with normal CRP levels compared to those with high CRP contents. In contrast, IL-10 levels in T2DM patients with high CRP levels were dramatically decreased. P2X7 receptor expression in monocytes from T2DM patients with high CRP levels was significantly increased in comparison with healthy individuals and T2DM patients with normal CRP levels. These findings indicated that P2X7 receptor in peripheral blood monocytes may be involved in the pathological changes of T2DM, particularly affecting patients with high CRP levels.

  17. ATP/P2X7 axis modulates myeloid-derived suppressor cell functions in neuroblastoma microenvironment.

    Science.gov (United States)

    Bianchi, G; Vuerich, M; Pellegatti, P; Marimpietri, D; Emionite, L; Marigo, I; Bronte, V; Di Virgilio, F; Pistoia, V; Raffaghello, L

    2014-03-20

    Tumor microenvironment of solid tumors is characterized by a strikingly high concentration of adenosine and ATP. Physiological significance of this biochemical feature is unknown, but it has been suggested that it may affect infiltrating immune cell responses and tumor progression. There is increasing awareness that many of the effects of extracellular ATP on tumor and inflammatory cells are mediated by the P2X7 receptor (P2X7R). Aim of this study was to investigate whether: (i) extracellular ATP is a component of neuroblastoma (NB) microenvironment, (ii) myeloid-derived suppressor cells (MDSCs) express functional P2X7R and (iii) the ATP/P2X7R axis modulates MDSC functions. Our results show that extracellular ATP was detected in NB microenvironment in amounts that increased in parallel with tumor progression. The percentage of CD11b(+)/Gr-1(+) cells was higher in NB-bearing mice compared with healthy animals. Within the CD11b/Gr-1(+) population, monocytic MDSCs (M-MDSCs) produced higher levels of reactive oxygen species (ROS), arginase-1 (ARG-1), transforming growth factor-β1 (TGF-β1) and stimulated more potently in vivo tumor growth, as compared with granulocytic MDSCs (G-MDSCs). P2X7R of M-MDSCs was localized at the plasma membrane, coupled to increased functionality, upregulation of ARG-1, TGF-β1 and ROS. Quite surprisingly, the P2X7R in primary MDSCs as well as in the MSC-1 and MSC-2 lines was uncoupled from cytotoxicity. This study describes a novel scenario in which MDSC immunosuppressive functions are modulated by the ATP-enriched tumor microenvironment.

  18. P2X7 receptor inhibition interrupts the progression of seizures in immature rats and reduces hippocampal damage

    NARCIS (Netherlands)

    Mesuret, G.; Engel, T.G.P.; Hessel, E.V.; Sanz-Rodriguez, A.; Jimenez-Pacheco, A.; Miras-Portugal, M.T.; Diaz-Hernandez, M.; Henshall, D.C.

    2014-01-01

    AIMS: Early-life seizures, particularly when prolonged, may be harmful to the brain. Current pharmacotherapy is often ineffective; therefore, novel neuro- and/or glio-transmitter systems should be explored for targeting. The P2X7 receptor is a cation-permeable channel with trophic and excitability

  19. Chronic administration of the selective P2X3, P2X2/3 receptor antagonist, A-317491, transiently attenuates cancer-induced bone pain in mice

    DEFF Research Database (Denmark)

    Hansen, Rikke Rie; Nasser, Arafat; Falk, Sarah

    2012-01-01

    The purinergic P2X3 and P2X2/3 receptors are in the peripheral nervous system almost exclusively confined to afferent sensory neurons, where they are found both at peripheral and central synapses. The P2X3 receptor is implicated in both neuropathic and inflammatory pain. However, the role of the ......X3 receptor in chronic cancer-induced bone pain is less known. Here we investigated the effect of systemic acute and chronic administration of the selective P2X3, P2X2/3 receptor antagonist (5-[[[(3-Phenoxyphenyl)methyl][(1S)-1,2,3,4-tetrahydro-1-naphthalenyl]amino]carbonyl]-1...

  20. P2X1 receptors localized in lipid rafts mediate ATP motor responses in the human vas deferens longitudinal muscles.

    Science.gov (United States)

    Donoso, María Verónica; Norambuena, Andrés; Navarrete, Camilo; Poblete, Inés; Velasco, Alfredo; Huidobro-Toro, Juan Pablo

    2014-02-01

    To assess the role of the P2X1 receptors (P2X1R) in the longitudinal and circular layers of the human vas deferens, ex vivo-isolated strips or rings were prepared from tissue biopsies to record isometric contractions. To ascertain its membrane distribution, tissue extracts were analyzed by immunoblotting following sucrose gradient ultracentrifugation. ATP, alpha,beta-methylene ATP, or electrical field stimulation elicited robust contractions of the longitudinal layer but not of the circular layer which demonstrated inconsistent responses. Alpha,beta-methylene ATP generated stronger and more robust contractions than ATP. In parallel, prostatic segments of the rat vas deferens were examined. The motor responses in both species were not sustained but decayed within the first minute, showing desensitization to additional applications. Cross-desensitization was established between alpha,beta-methylene ATP or ATP-evoked contractions and electrical field stimulation-induced contractions. Full recovery of the desensitized motor responses required more than 30 min and showed a similar pattern in human and rat tissues. Immunoblot analysis of the human vas deferens extracts revealed a P2X1R oligomer of approximately 200 kDa under nonreducing conditions, whereas dithiothreitol-treated extracts showed a single band of approximately 70 kDa. The P2X1R was identified in ultracentrifugation fractions containing 15%-29% sucrose; the receptor localized in the same fractions as flotillin-1, indicating that it regionalized into smooth muscle lipid rafts. In conclusion, ATP plays a key role in human vas deferens contractile responses of the longitudinal smooth muscle layer, an effect mediated through P2X1Rs.

  1. P2X receptor channels in endocrine glands

    Czech Academy of Sciences Publication Activity Database

    Stojilkovic, S. S.; Zemková, Hana

    2013-01-01

    Roč. 2, č. 4 (2013), s. 173-180 ISSN 2190-460X R&D Projects: GA ČR(CZ) GBP304/12/G069 Institutional support: RVO:67985823 Keywords : ATP * purinergic P2X receptor channels * pituitary * endocrine glands Subject RIV: ED - Physiology

  2. P2X7 receptor blockade protects against cisplatin-induced nephrotoxicity in mice by decreasing the activities of inflammasome components, oxidative stress and caspase-3

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yuanyuan; Yuan, Fahuan; Cao, Xuejiao [Department of Nephrology, Xinqiao Hospital, PLA, Third Military Medical University, Chongqing 400037 (China); Zhai, Zhifang [Department of Dermatology, Southwest Hospital, Third Military Medical University, Chongqing 400038 (China); Gang Huang [Department of Medical Genetics, Third Military Medical University, Chongqing 430038 (China); Du, Xiang; Wang, Yiqin; Zhang, Jingbo; Huang, Yunjian; Zhao, Jinghong [Department of Nephrology, Xinqiao Hospital, PLA, Third Military Medical University, Chongqing 400037 (China); Hou, Weiping, E-mail: hwp0518@aliyun.com [Department of Nephrology, Xinqiao Hospital, PLA, Third Military Medical University, Chongqing 400037 (China)

    2014-11-15

    Nephrotoxicity is a common complication of cisplatin chemotherapy and thus limits the use of cisplatin in clinic. The purinergic 2X7 receptor (P2X7R) plays important roles in inflammation and apoptosis in some inflammatory diseases; however, its roles in cisplatin-induced nephrotoxicity remain unclear. In this study, we first assessed the expression of P2X7R in cisplatin-induced nephrotoxicity in C57BL/6 mice, and then we investigated the changes of renal function, histological injury, inflammatory response, and apoptosis in renal tissues after P2X7R blockade in vivo using an antagonist A-438079. Moreover, we measured the changes of nod-like receptor family, pyrin domain containing proteins (NLRP3) inflammasome components, oxidative stress, and proapoptotic genes in renal tissues in cisplatin-induced nephrotoxicity after treatment with A-438079. We found that the expression of P2X7R was significantly upregulated in the renal tubular epithelial cells in cisplatin-induced nephrotoxicity compared with that of the normal control group. Furthermore, pretreatment with A-438079 markedly attenuated the cisplatin-induced renal injury while lightening the histological damage, inflammatory response and apoptosis in renal tissue, and improved the renal function. These effects were associated with the significantly reduced levels of NLRP3 inflammasome components, oxidative stress, p53 and caspase-3 in renal tissues in cisplatin-induced nephrotoxicity. In conclusions, our studies suggest that the upregulated activity of P2X7R might play important roles in the development of cisplatin-induced nephrotoxicity, and P2X7R blockade might become an effective therapeutic strategy for this disease. - Highlights: • The P2X7R expression was markedly upregulated in cisplatin-induced nephrotoxicity. • P2X7R blockade significantly attenuated the cisplatin-induced renal injury. • P2X7R blockade reduced activities of NLRP3 inflammasome components in renal tissue. • P2X7R blockade

  3. Vascular endothelial cells mediate mechanical stimulation-induced enhancement of endothelin hyperalgesia via activation of P2X2/3 receptors on nociceptors.

    Science.gov (United States)

    Joseph, Elizabeth K; Green, Paul G; Bogen, Oliver; Alvarez, Pedro; Levine, Jon D

    2013-02-13

    Endothelin-1 (ET-1) is unique among a broad range of hyperalgesic agents in that it induces hyperalgesia in rats that is markedly enhanced by repeated mechanical stimulation at the site of administration. Antagonists to the ET-1 receptors, ET(A) and ET(B), attenuated both initial as well as stimulation-induced enhancement of hyperalgesia (SIEH) by endothelin. However, administering antisense oligodeoxynucleotide to attenuate ET(A) receptor expression on nociceptors attenuated ET-1 hyperalgesia but had no effect on SIEH, suggesting that this is mediated via a non-neuronal cell. Because vascular endothelial cells are both stretch sensitive and express ET(A) and ET(B) receptors, we tested the hypothesis that SIEH is dependent on endothelial cells by impairing vascular endothelial function with octoxynol-9 administration; this procedure eliminated SIEH without attenuating ET-1 hyperalgesia. A role for protein kinase Cε (PKCε), a second messenger implicated in the induction and maintenance of chronic pain, was explored. Intrathecal antisense for PKCε did not inhibit either ET-1 hyperalgesia or SIEH, suggesting no role for neuronal PKCε; however, administration of a PKCε inhibitor at the site of testing selectively attenuated SIEH. Compatible with endothelial cells releasing ATP in response to mechanical stimulation, P2X(2/3) receptor antagonists eliminated SIEH. The endothelium also appears to contribute to hyperalgesia in two ergonomic pain models (eccentric exercise and hindlimb vibration) and in a model of endometriosis. We propose that SIEH is produced by an effect of ET-1 on vascular endothelial cells, sensitizing its release of ATP in response to mechanical stimulation; ATP in turn acts at the nociceptor P2X(2/3) receptor.

  4. P2X Receptors and Synaptic Plasticity

    Czech Academy of Sciences Publication Activity Database

    Pankratov, Y.; Lalo, U.; Krishtal, A.; Verkhratsky, Alexei

    2009-01-01

    Roč. 158, č. 1 (2009), s. 137-148 ISSN 0306-4522 Institutional research plan: CEZ:AV0Z50390512 Keywords : ATP * P2X receptors * synaptic plasticity Subject RIV: FH - Neurology Impact factor: 3.292, year: 2009

  5. Identification of Human P2X1 Receptor-interacting Proteins Reveals a Role of the Cytoskeleton in Receptor Regulation*

    Science.gov (United States)

    Lalo, Ulyana; Roberts, Jonathan A.; Evans, Richard J.

    2011-01-01

    P2X1 receptors are ATP-gated ion channels expressed by smooth muscle and blood cells. Carboxyl-terminally His-FLAG-tagged human P2X1 receptors were stably expressed in HEK293 cells and co-purified with cytoskeletal proteins including actin. Disruption of the actin cytoskeleton with cytochalasin D inhibited P2X1 receptor currents with no effect on the time course of the response or surface expression of the receptor. Stabilization of the cytoskeleton with jasplakinolide had no effect on P2X1 receptor currents but decreased receptor mobility. P2X2 receptor currents were unaffected by cytochalasin, and P2X1/2 receptor chimeras were used to identify the molecular basis of actin sensitivity. These studies showed that the intracellular amino terminus accounts for the inhibitory effects of cytoskeletal disruption similar to that shown for lipid raft/cholesterol sensitivity. Stabilization of the cytoskeleton with jasplakinolide abolished the inhibitory effects of cholesterol depletion on P2X1 receptor currents, suggesting that lipid rafts may regulate the receptor through stabilization of the cytoskeleton. These studies show that the cytoskeleton plays an important role in P2X1 receptor regulation. PMID:21757694

  6. The selective antagonism of P2X7 and P2Y1 receptors prevents synaptic failure and affects cell proliferation induced by oxygen and glucose deprivation in rat dentate gyrus.

    Directory of Open Access Journals (Sweden)

    Giovanna Maraula

    Full Text Available Purinergic P2X and P2Y receptors are broadly expressed on both neurons and glial cells in the central nervous system (CNS, including dentate gyrus (DG. The aim of this research was to determine the synaptic and proliferative response of the DG to severe oxygen and glucose deprivation (OGD in acute rat hippocampal slices and to investigate the contribution of P2X7 and P2Y1 receptor antagonism to recovery of synaptic activity after OGD. Extracellular field excitatory post-synaptic potentials (fEPSPs in granule cells of the DG were recorded from rat hippocampal slices. Nine-min OGD elicited an irreversible loss of fEPSP and was invariably followed by the appearance of anoxic depolarization (AD. Application of MRS2179 (selective antagonist of P2Y1 receptor and BBG (selective antagonist of P2X7 receptor, before and during OGD, prevented AD appearance and allowed a significant recovery of neurotransmission after 9-min OGD. The effects of 9-min OGD on proliferation and maturation of cells localized in the subgranular zone (SGZ of slices prepared from rats treated with 5-Bromo-2'-deoxyuridine (BrdU were investigated. Slices were further incubated with an immature neuron marker, doublecortin (DCX. The number of BrdU+ cells in the SGZ was significantly decreased 6 hours after OGD. This effect was antagonized by BBG, but not by MRS2179. Twenty-four hours after 9-min OGD, the number of BrdU+ cells returned to control values and a significant increase of DCX immunofluorescence was observed. This phenomenon was still evident when BBG, but not MRS2179, was applied during OGD. Furthermore, the P2Y1 antagonist reduced the number of BrdU+ cells at this time. The data demonstrate that P2X7 and P2Y1 activation contributes to early damage induced by OGD in the DG. At later stages after the insult, P2Y1 receptors might play an additional and different role in promoting cell proliferation and maturation in the DG.

  7. Ginsenoside 25-OCH3-PPD promotes activity of LXRs to ameliorate P2X7R-mediated NLRP3 inflammasome in the development of hepatic fibrosis.

    Science.gov (United States)

    Han, Xin; Song, Jian; Lian, Li-Hua; Yao, You-Li; Shao, Dan-Yang; Fan, Ying; Hou, Li-Shuang; Wang, Ge; Zheng, Shuang; Wu, Yan-Ling; Nan, Ji-Xing

    2018-06-22

    Ginseng is widely used in energy drinks, dietary supplements and herbal medicines, and its pharmacological actions are related with energy metabolism. As an important modulating energy metabolism pathway, liver X receptors (LXRs) can promote the resolving of hepatic fibrosis and inflammation. The present study aims to evaluate the regulation of 25-OCH3-PPD, a ginsenoside isolated from Panax ginseng, against hepatic fibrosis and inflammation in thioacetamide (TAA)-stimulated mice by activating LXRs pathway. 25-OCH3-PPD decreases serum ALT/AST levels and improves the histological pathology of liver in TAA-induced mice; attenuates transcripts of pro-fibrogenic markers associated with hepatic stellate cell activation; attenuates the levels of pro-Inflammatory cytokines and blocks apoptosis happened in liver; inhibits NLRP3 inflammasome by affecting P2X7R activation; regulates PI3K/Akt and LKB1/AMPK-SIRT1. 25-OCH3-PPD also facilitates LX25Rs and FXR activities decreased by TAA stimulation. 25-OCH3-PPD also decreases α-SMA via regulation of LXRs and P2X7R-NLRP3 in vitro. Our data suggest the possibility that 25-OCH3-PPD promotes activity of LXRs to ameliorate P2X7R-mediated NLRP3 inflammasome in the development of hepatic fibrosis.

  8. P2X7 Receptors Drive Spine Synapse Plasticity in the Learned Helplessness Model of Depression.

    Science.gov (United States)

    Otrokocsi, Lilla; Kittel, Ágnes; Sperlágh, Beáta

    2017-10-01

    Major depressive disorder is characterized by structural and functional abnormalities of cortical and limbic brain areas, including a decrease in spine synapse number in the dentate gyrus of the hippocampus. Recent studies highlighted that both genetic and pharmacological invalidation of the purinergic P2X7 receptor (P2rx7) leads to antidepressant-like phenotype in animal experiments; however, the impact of P2rx7 on depression-related structural changes in the hippocampus is not clarified yet. Effects of genetic deletion of P2rx7s on depressive-like behavior and spine synapse density in the dentate gyrus were investigated using the learned helplessness mouse model of depression. We demonstrate that in wild-type animals, inescapable footshocks lead to learned helplessness behavior reflected in increased latency and number of escape failures to subsequent escapable footshocks. This behavior is accompanied with downregulation of mRNA encoding P2rx7 and decrease of spine synapse density in the dentate gyrus as determined by electron microscopic stereology. In addition, a decrease in synaptopodin but not in PSD95 and NR2B/GluN2B protein level was also observed under these conditions. Whereas the absence of P2rx7 was characterized by escape deficit, no learned helpless behavior is observed in these animals. Likewise, no decrease in spine synapse number and synaptopodin protein levels was detected in response to inescapable footshocks in P2rx7-deficient animals. Our findings suggest the endogenous activation of P2rx7s in the learned helplessness model of depression and decreased plasticity of spine synapses in P2rx7-deficient mice might explain the resistance of these animals to repeated stressful stimuli. © The Author 2017. Published by Oxford University Press on behalf of CINP.

  9. Effect of electroacupuncture on the cervicospinal P2X7 receptor/fractalkine/CX3CR1 signaling pathway in a rat neck-incision pain model.

    Science.gov (United States)

    Gao, Y H; Li, C W; Wang, J Y; Tan, L H; Duanmu, C L; Jing, X H; Chang, X R; Liu, J L

    2017-06-01

    Increasing evidence supports that acupuncture intervention is an effective approach for intraoperative and postoperative pain. Neuron-microglia crosstalk, mediated by the purinergic P2X7 receptor (R)/fractalkine/CX3CR1 cascade in the spinal cord dorsal horn, plays a pivotal role in pain processing. However, its involvement in the analgesic effect of electroacupuncture (EA) remains unclear. In this study, a rat neck-incision pain model was established by making a longitudinal incision along the midline of the neck and subsequent repeated mechanical stimulation. EA stimulation was applied to bilateral LI18, LI4-PC6, or ST36-GB34. The thermal pain threshold, cervicospinal ATP concentration, expression levels of purinergic P2XR and P2YR subunits mRNAs, and fractalkine, CX3CR1 and p38 MAPK proteins, were detected separately. The neck incision induced strong thermal hyperalgesia and upregulation of spinal ATP within 48 h. No significant change was found in thermal hyperalgesia after a single session of EA intervention. However, a single session of EA dramatically enhanced the neck incision-induced upregulation of ATP and upregulated the expression of P2X7R, which was reversed by two sessions of EA. Two sessions of EA at bilateral LI18 or LI4-PC6 attenuated hyperalgesia significantly, accompanied with downregulation of P2X7R/fractalkine/ CX3CR1 signaling after three sessions of EA. EA stimulation of LI18 or LI4-PC6 alleviates thermal hyperalgesia in neck-incision pain rats, which may be associated with its effects in regulating the neck incision-induced increase of ATP and P2X7R and subsequently suppressing fractalkine/CX3CR1 signaling in the cervical spinal cord.

  10. Pulmonary infection with hypervirulent Mycobacteria reveals a crucial role for the P2X7 receptor in aggressive forms of tuberculosis.

    Directory of Open Access Journals (Sweden)

    Eduardo P Amaral

    2014-07-01

    Full Text Available The purinergic P2X7 receptor (P2X7R is a sensor of extracellular ATP, a damage-associated molecule that is released from necrotic cells and that induces pro-inflammatory cytokine production and cell death. To investigate whether the innate immune response to damage signals could contribute to the development of pulmonary necrotic lesions in severe forms of tuberculosis, disease progression was examined in C57BL/6 and P2X7R-/- mice that were intratracheally infected with highly virulent mycobacterial strains (Mycobacterium tuberculosis strain 1471 of the Beijing genotype family and Mycobacterium bovis strain MP287/03. The low-dose infection of C57BL/6 mice with bacteria of these strains caused the rapid development of extensive granulomatous pneumonia with necrotic areas, intense bacillus dissemination and anticipated animal death. In contrast, in P2X7R-/- mice, the lung pathology presented with moderate infiltrates of mononuclear leukocytes without visible signs of necrosis; the disease attenuation was accompanied by a delay in mortality. In vitro, the hypervirulent mycobacteria grew rapidly inside macrophages and induced death by a P2X7R-dependent mechanism that facilitated the release of bacilli. Furthermore, these bacteria were resistant to the protective mechanisms elicited in macrophages following extracellular ATP stimulation. Based on this study, we propose that the rapid intracellular growth of hypervirulent mycobacteria results in massive macrophage damage. The ATP released by damaged cells engages P2X7R and accelerates the necrotic death of infected macrophages and the release of bacilli. This vicious cycle exacerbates pneumonia and lung necrosis by promoting widespread cell destruction and bacillus dissemination. These findings suggest the use of drugs that have been designed to inhibit the P2X7R as a new therapeutic approach to treat the aggressive forms of tuberculosis.

  11. The Locus Coeruleus–Norepinephrine System Mediates Empathy for Pain through Selective Up-Regulation of P2X3 Receptor in Dorsal Root Ganglia in Rats

    Directory of Open Access Journals (Sweden)

    Yun-Fei Lü

    2017-09-01

    results, empathy for pain observed in the CO rats is likely to be mediated by activation of the top-down mPFC-LC/NE-sympathoadrenomedullary (SAM system that further up-regulates P2X3 receptors in the periphery, however, social stress observed in the NCO rats is mediated by activation of both hypothalamic-pituitary-adrenocortical axis and SAM axis.

  12. P2X1 Receptor Antagonists Inhibit HIV-1 Fusion by Blocking Virus-Coreceptor Interactions.

    Science.gov (United States)

    Giroud, Charline; Marin, Mariana; Hammonds, Jason; Spearman, Paul; Melikyan, Gregory B

    2015-09-01

    HIV-1 Env glycoprotein-mediated fusion is initiated upon sequential binding of Env to CD4 and the coreceptor CXCR4 or CCR5. Whereas these interactions are thought to be necessary and sufficient to promote HIV-1 fusion, other host factors can modulate this process. Previous studies reported potent inhibition of HIV-1 fusion by selective P2X1 receptor antagonists, including NF279, and suggested that these receptors play a role in HIV-1 entry. Here we investigated the mechanism of antiviral activity of NF279 and found that this compound does not inhibit HIV-1 fusion by preventing the activation of P2X1 channels but effectively blocks the binding of the virus to CXCR4 or CCR5. The notion of an off-target effect of NF279 on HIV-1 fusion is supported by the lack of detectable expression of P2X1 receptors in cells used in fusion experiments and by the fact that the addition of ATP or the enzymatic depletion of ATP in culture medium does not modulate viral fusion. Importantly, NF279 fails to inhibit HIV-1 fusion with cell lines and primary macrophages when added at an intermediate stage downstream of Env-CD4-coreceptor engagement. Conversely, in the presence of NF279, HIV-1 fusion is arrested downstream of CD4 binding but prior to coreceptor engagement. NF279 also antagonizes the signaling function of CCR5, CXCR4, and another chemokine receptor, as evidenced by the suppression of calcium responses elicited by specific ligands and by recombinant gp120. Collectively, our results demonstrate that NF279 is a dual HIV-1 coreceptor inhibitor that interferes with the functional engagement of CCR5 and CXCR4 by Env. Inhibition of P2X receptor activity suppresses HIV-1 fusion and replication, suggesting that P2X signaling is involved in HIV-1 entry. However, mechanistic experiments conducted in this study imply that P2X1 receptor is not expressed in target cells or involved in viral fusion. Instead, we found that inhibition of HIV-1 fusion by a specific P2X1 receptor antagonist, NF

  13. Novel protective role of endogenous cardiac myocyte P2X4 receptors in heart failure.

    Science.gov (United States)

    Yang, Tiehong; Shen, Jian-bing; Yang, Ronghua; Redden, John; Dodge-Kafka, Kimberly; Grady, James; Jacobson, Kenneth A; Liang, Bruce T

    2014-05-01

    Heart failure (HF), despite continuing progress, remains a leading cause of mortality and morbidity. P2X4 receptors (P2X4R) have emerged as potentially important molecules in regulating cardiac function and as potential targets for HF therapy. Transgenic P2X4R overexpression can protect against HF, but this does not explain the role of native cardiac P2X4R. Our goal is to define the physiological role of endogenous cardiac myocyte P2X4R under basal conditions and during HF induced by myocardial infarction or pressure overload. Mice established with conditional cardiac-specific P2X4R knockout were subjected to left anterior descending coronary artery ligation-induced postinfarct or transverse aorta constriction-induced pressure overload HF. Knockout cardiac myocytes did not show P2X4R by immunoblotting or by any response to the P2X4R-specific allosteric enhancer ivermectin. Knockout hearts showed normal basal cardiac function but depressed contractile performance in postinfarct and pressure overload models of HF by in vivo echocardiography and ex vivo isolated working heart parameters. P2X4R coimmunoprecipitated and colocalized with nitric oxide synthase 3 (eNOS) in wild-type cardiac myocytes. Mice with cardiac-specific P2X4R overexpression had increased S-nitrosylation, cyclic GMP, NO formation, and were protected from postinfarct and pressure overload HF. Inhibitor of eNOS, L-N(5)-(1-iminoethyl)ornithine hydrochloride, blocked the salutary effect of cardiac P2X4R overexpression in postinfarct and pressure overload HF as did eNOS knockout. This study establishes a new protective role for endogenous cardiac myocyte P2X4R in HF and is the first to demonstrate a physical interaction between the myocyte receptor and eNOS, a mediator of HF protection. © 2014 American Heart Association, Inc.

  14. Association between NLPR1, NLPR3, and P2X7R Gene Polymorphisms with Partial Seizures

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    Haidong Wang

    2017-01-01

    Full Text Available Objectives. Clinical and experimental evidence has clarified that the inflammatory processes within the brain play a pivotal role in the pathophysiology of seizures and epilepsy. Inflammasomes and P2X7 purinergic receptor (P2X7R are important mediators during the inflammatory process. Therefore, we investigated the possible association between partial seizures and inflammasomes NLPR1, NLRP3, and P2X7R gene polymorphisms in the present study. Method. A total of 163 patients and 201 health controls were enrolled in this study and polymorphisms of NLPR1, NLRP3, and P2X7R genes were detected using polymerase chain reaction- (PCR- ligase detection reaction method. Result. The frequency of rs878329 (G>C genotype with C (CG + CC was significantly lower among patients with partial seizures relative to controls (OR = 2.033, 95% CI = 1.290–3.204, p=0.002 for GC + CC versus GG. Intriguingly, we found that the significant difference of rs878329 (G>C genotype and allele frequency only existed among males (OR = 2.542, 95% CI = 1.344–4.810, p=0.004 for GC + CC versus GG, while there was no statistically significant difference among females. However, no significant results were presented for the genotype distributions of rs8079034, rs4612666, rs10754558, rs2027432, rs3751143, and rs208294 polymorphisms between patients and controls. Conclusion. Our study demonstrated the potentially significant role of NLRP1 rs878329 (G>C in developing susceptibility to the partial seizures in a Chinese Han population.

  15. Purinergic control of inflammation and thrombosis: Role of P2X1 receptors

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    Cécile Oury

    2015-01-01

    Full Text Available Inflammation shifts the hemostatic mechanisms in favor of thrombosis. Upon tissue damage or infection, a sudden increase of extracellular ATP occurs, that might contribute to the crosstalk between inflammation and thrombosis. On platelets, P2X1 receptors act to amplify platelet activation and aggregation induced by other platelet agonists. These receptors critically contribute to thrombus stability in small arteries. Besides platelets, studies by our group indicate that these receptors are expressed by neutrophils. They promote neutrophil chemotaxis, both in vitro and in vivo. In a laser-induced injury mouse model of thrombosis, it appears that neutrophils are required to initiate thrombus formation and coagulation activation on inflamed arteriolar endothelia. In this model, by using P2X1−/− mice, we recently showed that P2X1 receptors, expressed on platelets and neutrophils, play a key role in thrombus growth and fibrin generation. Intriguingly, in a model of endotoxemia, P2X1−/− mice exhibited aggravated oxidative tissue damage, along with exacerbated thrombocytopenia and increased activation of coagulation, which translated into higher susceptibility to septic shock. Thus, besides its ability to recruit neutrophils and platelets on inflamed endothelia, the P2X1 receptor also contributes to limit the activation of circulating neutrophils under systemic inflammatory conditions. Taken together, these data suggest that P2X1 receptors are involved in the interplay between platelets, neutrophils and thrombosis. We propose that activation of these receptors by ATP on neutrophils and platelets represents a new mechanism that regulates thrombo-inflammation.

  16. Potential Involvement of P2 Receptors in the Pathological Processes of Hyperthyroidism: A Pilot Study.

    Science.gov (United States)

    Hong, Wu; Li, Guodong; Nie, Yijun; Zou, Lifang; Zhang, Xi; Liu, Shuangmei; Li, Guilin; Xu, Hong; Zhang, Chun-Ping; Liang, Shangdong

    2016-05-01

    Symptoms of hyperthyroidism manifest mainly as changes in the nervous and metabolic systems. Whether P2X receptors (ionotropic ATP purinergic receptors, including P2X3 receptor and P2X7 receptor) are involved in the alterations of these disorders still remains unclear. Thus, this study aimed to assess the association of hyperthyroidism with the expression of P2X3 and P2X7 receptors and the concentrations of ATP in blood leukocytes and catecholamine. Twelve healthy subjects and twelve patients diagnosed with hyperthyroidism were recruited. Serum free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) levels had been detected by chemiluminescence method. Meanwhile, the catecholamine levels (including adrenaline, noradrenaline, and dopamine) in plasma, ATP level and P2X receptors (including P2X3 receptor and P2X7 receptor) in peripheral blood had been detected by high performance liquid chromatography, bioluminescence method, and reverse transcription polymerase chain reaction, respectively. Levels of epinephrine and norepinephrine were significantly higher in the hyperthyroidism group compared with the control group. The concentration of ATP in the hyperthyroidism group was significantly higher than its in the control group. The expression of P2X3 mRNA and P2X7 mRNA in hyperthyroidism group were significantly increased compared with those in control group. In a conclusion, there is a relationship between the elevated expression of P2X3 receptor and P2X7 receptor in peripheral blood leukocytes and high serum epinephrine and norepinephrine levels in hyperthyroidism patients. © 2016 by the Association of Clinical Scientists, Inc.

  17. The mechanism of functional up-regulation of P2X3 receptors of trigeminal sensory neurons in a genetic mouse model of familial hemiplegic migraine type 1 (FHM-1.

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    Swathi K Hullugundi

    Full Text Available A knock-in (KI mouse model of FHM-1 expressing the R192Q missense mutation of the Cacna1a gene coding for the α1 subunit of CaV2.1 channels shows, at the level of the trigeminal ganglion, selective functional up-regulation of ATP -gated P2X3 receptors of sensory neurons that convey nociceptive signals to the brainstem. Why P2X3 receptors are constitutively more responsive, however, remains unclear as their membrane expression and TRPV1 nociceptor activity are the same as in wildtype (WT neurons. Using primary cultures of WT or KI trigeminal ganglia, we investigated whether soluble compounds that may contribute to initiating (or maintaining migraine attacks, such as TNFα, CGRP, and BDNF, might be responsible for increasing P2X3 receptor responses. Exogenous application of TNFα potentiated P2X3 receptor-mediated currents of WT but not of KI neurons, most of which expressed both the P2X3 receptor and the TNFα receptor TNFR2. However, sustained TNFα neutralization failed to change WT or KI P2X3 receptor currents. This suggests that endogenous TNFα does not regulate P2X3 receptor responses. Nonetheless, on cultures made from both genotypes, exogenous TNFα enhanced TRPV1 receptor-mediated currents expressed by a few neurons, suggesting transient amplification of TRPV1 nociceptor responses. CGRP increased P2X3 receptor currents only in WT cultures, although prolonged CGRP receptor antagonism or BDNF neutralization reduced KI currents to WT levels. Our data suggest that, in KI trigeminal ganglion cultures, constitutive up-regulation of P2X3 receptors probably is already maximal and is apparently contributed by basal CGRP and BDNF levels, thereby rendering these neurons more responsive to extracellular ATP.

  18. Regulation of Hippocampal 5-HT Release by P2X7 Receptors in Response to Optogenetic Stimulation of Median Raphe Terminals of Mice

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    Flóra Gölöncsér

    2017-10-01

    Full Text Available Serotonergic and glutamatergic neurons of median raphe region (MRR play a pivotal role in the modulation of affective and cognitive functions. These neurons synapse both onto themselves and remote cortical areas. P2X7 receptors (P2rx7 are ligand gated ion channels expressed by central presynaptic excitatory nerve terminals and involved in the regulation of neurotransmitter release. P2rx7s are implicated in various neuropsychiatric conditions such as schizophrenia and depression. Here we investigated whether 5-HT release released from the hippocampal terminals of MRR is subject to modulation by P2rx7s. To achieve this goal, an optogenetic approach was used to selectively activate subpopulation of serotonergic terminals derived from the MRR locally, and one of its target area, the hippocampus. Optogenetic activation of neurons in the MRR with 20 Hz was correlated with freezing and enhanced locomotor activity of freely moving mice and elevated extracellular levels of 5-HT, glutamate but not GABA in vivo. Similar optical stimulation (OS significantly increased [3H]5-HT and [3H]glutamate release in acute MRR and hippocampal slices. We examined spatial and temporal patterns of [3H]5-HT release and the interaction between the serotonin and glutamate systems. Whilst [3H]5-HT release from MRR neurons was [Ca2+]o-dependent and sensitive to TTX, CNQX and DL-AP-5, release from hippocampal terminals was not affected by the latter drugs. Hippocampal [3H]5-HT released by electrical but not OS was subject to modulation by 5- HT1B/D receptors agonist sumatriptan (1 μM, whereas the selective 5-HT1A agonist buspirone (0.1 μM was without effect. [3H]5-HT released by electrical and optical stimulation was decreased in mice genetically deficient in P2rx7s, and after perfusion with selective P2rx7 antagonists, JNJ-47965567 (0.1 μM, and AZ-10606120 (0.1 μM. Optical and electrical stimulation elevated the extracellular level of ATP. Our results demonstrate for the

  19. Autocrine Regulation of UVA-Induced IL-6 Production via Release of ATP and Activation of P2Y Receptors

    Science.gov (United States)

    Kawano, Ayumi; Kadomatsu, Remi; Ono, Miyu; Kojima, Shuji; Tsukimoto, Mitsutoshi; Sakamoto, Hikaru

    2015-01-01

    Extracellular nucleotides, such as ATP, are released from cells in response to various stimuli and act as intercellular signaling molecules through activation of P2 receptors. Exposure to the ultraviolet radiation A (UVA) component of sunlight causes molecular and cellular damage, and in this study, we investigated the involvement of extracellular nucleotides and P2 receptors in the UVA-induced cellular response. Human keratinocyte-derived HaCaT cells were irradiated with a single dose of UVA (2.5 J/cm2), and ATP release and interleukin (IL)-6 production were measured. ATP was released from cells in response to UVA irradiation, and the release was blocked by pretreatment with inhibitors of gap junction hemichannels or P2X7 receptor antagonist. IL-6 production was increased after UVA irradiation, and this increase was inhibited by ecto-nucleotidase or by antagonists of P2Y11 or P2Y13 receptor. These results suggest that UVA-induced IL-6 production is mediated by release of ATP through hemichannels and P2X7 receptor, followed by activation of P2Y11 and P2Y13 receptors. Interestingly, P2Y11 and P2Y13 were associated with the same pattern of IL-6 production, though they trigger different intracellular signaling cascades: Ca2+-dependent and PI3K-dependent, respectively. Thus, IL-6 production in response to UVA-induced ATP release involves at least two distinct pathways, mediated by activation of P2Y11 and P2Y13 receptors. PMID:26030257

  20. Single-nucleotide polymorphisms in the P2X7 receptor gene are associated with post-menopausal bone loss and vertebral fractures

    DEFF Research Database (Denmark)

    Rye Jørgensen, Niklas; Husted, Lise Bjerre; Skarratt, Kristen K

    2012-01-01

    to bone mass and fracture incidence in post-menopausal women. A total of 1694 women (aged 45-58) participating in the Danish Osteoporosis Prevention Study were genotyped for 12 functional P2X7 receptor variants. Bone mineral density was determined at baseline and after 10 years. In addition, vertebral...... had increased bone loss. In contrast, the Gln460Arg polymorphism was associated with protection against bone loss. The Ala348Thr polymorphism was associated with a lower vertebral fracture incidence 10 years after menopause. Finally, we developed a risk model, which integrated P2RX7 genotypes. Using...

  1. P2X7 mRNA expression in non-small cell lung cancer: MicroRNA regulation and prognostic value

    OpenAIRE

    BOLDRINI, LAURA; GIORDANO, MIRELLA; ALÌ, GRETA; MELFI, FRANCA; ROMANO, GAETANO; LUCCHI, MARCO; FONTANINI, GABRIELLA

    2014-01-01

    The human P2X7 receptor is significant and exhibits several functions in neoplasia. At present, little is known with regard to its regulation. P2X7 expression may be regulated post-transcriptionally and putative microRNA (miRNA) binding sites are considered to be involved. The aim of this study was to determine whether miRNAs (miR-21, let-7 g and miR-205) regulate P2X7 mRNA stability. In addition, the impact of P2X7 expression in patients with non-small cell lung cancer (NSCLC) was investigat...

  2. Astrocytes protect neurons against methylmercury via ATP/P2Y(1) receptor-mediated pathways in astrocytes.

    Science.gov (United States)

    Noguchi, Yusuke; Shinozaki, Youichi; Fujishita, Kayoko; Shibata, Keisuke; Imura, Yoshio; Morizawa, Yosuke; Gachet, Christian; Koizumi, Schuichi

    2013-01-01

    Methylmercury (MeHg) is a well known environmental pollutant that induces serious neuronal damage. Although MeHg readily crosses the blood-brain barrier, and should affect both neurons and glial cells, how it affects glia or neuron-to-glia interactions has received only limited attention. Here, we report that MeHg triggers ATP/P2Y1 receptor signals in astrocytes, thereby protecting neurons against MeHg via interleukin-6 (IL-6)-mediated pathways. MeHg increased several mRNAs in astrocytes, among which IL-6 was the highest. For this, ATP/P2Y1 receptor-mediated mechanisms were required because the IL-6 production was (i) inhibited by a P2Y1 receptor antagonist, MRS2179, (ii) abolished in astrocytes obtained from P2Y1 receptor-knockout mice, and (iii) mimicked by exogenously applied ATP. In addition, (iv) MeHg released ATP by exocytosis from astrocytes. As for the intracellular mechanisms responsible for IL-6 production, p38 MAP kinase was involved. MeHg-treated astrocyte-conditioned medium (ACM) showed neuro-protective effects against MeHg, which was blocked by anti-IL-6 antibody and was mimicked by the application of recombinant IL-6. As for the mechanism of neuro-protection by IL-6, an adenosine A1 receptor-mediated pathway in neurons seems to be involved. Taken together, when astrocytes sense MeHg, they release ATP that autostimulates P2Y1 receptors to upregulate IL-6, thereby leading to A1 receptor-mediated neuro-protection against MeHg.

  3. Chronic restraint stress exacerbates nociception and inflammatory response induced by bee venom in rats: the role of the P2X7 receptors.

    Science.gov (United States)

    Li, Xiao-Qiu; Li, Man; Zhou, Zhong-He; Liu, Bao-Jun; Chen, Hui-Sheng

    2016-02-01

    Chronic restraint stress exacerbates pain and inflammation. The present study was designed to evaluate the effect of chronic restraint stress on inflammatory pain induced by subcutaneous injection of bee venom (BV). First, we investigated: (1) the effect of two-week restraint stress with daily 2 or 8 h on the baseline paw withdrawal mechanical threshold (PWMT), paw withdrawal thermal latency (PWTL) and paw circumference (PC); (2) the effect of chronic stress on the spontaneous paw-flinching reflex (SPFR), decrease in PWM, PWTL and increase in PC of the injected paw induced by BV. The results showed that (1) chronic restraint decreased significantly the PWMT and inhibited significantly the increase in PC, but had no effect on PWTL, compared with control group; (2) chronic restraint enhanced significantly BV-induced SPFR and inflammatory swelling of the injected paw. In a second series of experiments, the role of P2X7 receptor (P2X7R) in the enhancement of BV-induced inflammatory pain produced by chronic restraint stress was determined. Systemic pretreatment with P2X7R antagonist completely reversed the decrease in PWMT produced by chronic restraint, inhibited significantly the enhancement of BV-induced inflammatory pain produced by chronic restraint stress. Taken together, our data indicate that chronic restraint stress-enhanced nociception and inflammation in the BV pain model, possibly involving the P2X7R.

  4. Rab5 regulates internalisation of P2X4 receptors and potentiation by ivermectin.

    Science.gov (United States)

    Stokes, Leanne

    2013-03-01

    The P2X4 receptor is an ATP-gated ion channel expressed in neurons, endothelia and immune cells. Plasma membrane expression of P2X4 is regulated by dynamin-dependent endocytosis, and this study identifies a Rab5-dependent pathway of receptor internalisation. Expression of Rab5 constructs altered the distribution of P2X4 in HEK-293 cells, and both constitutive internalisation and agonist-induced desensitisation of P2X4 were increased by co-expression of wild-type Rab5 or constitutively active Rab5 (Q79L). Expression of inactive dynamin K44A and Rab5 S34N constructs abolished agonist-induced desensitisation, suggesting internalisation as the underlying mechanism. Blocking P2X4 internalisation in this way also abolished potentiation of ATP-induced currents by the allosteric modulator ivermectin. This suggests that the dynamin-Rab5 internalisation pathway is essential for the ivermectin potentiation effect. In agreement with this hypothesis, the co-expression of wild-type dynamin, wild-type Rab5 or active Rab5 (Q79L) could increase the potentiation of the ATP-induced P2X4 response by ivermectin. These findings highlight Rab5 GTPase as a key regulator of P2X4 receptor cell surface expression and internalisation.

  5. Subfailure overstretch injury leads to reversible functional impairment and purinergic P2X7 receptor activation in intact vascular tissue

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    Weifeng Luo

    2016-09-01

    Full Text Available Vascular stretch injury is associated with blunt trauma, vascular surgical procedures, and harvest of human saphenous vein for use in vascular bypass grafting. A model of subfailure overstretch in rat abdominal aorta was developed to characterize surgical vascular stretch injury. Longitudinal stretch of rat aorta was characterized ex vivo. Stretch to the haptic endpoint where the tissues would no longer lengthen, occurred at twice the resting length. The stress produced at this length was greater than physiologic mechanical forces but well below the level of mechanical disruption. Functional responses were determined in a muscle bath and this subfailure overstretch injury led to impaired smooth muscle function that was partially reversed by treatment with purinergic receptor (P2X7R antagonists. These data suggest that vasomotor dysfunction caused by subfailure overstretch injury may be due to activation of P2X7R. These studies have implications for our understanding of mechanical stretch injury of blood vessels and offer novel therapeutic opportunities.

  6. Comparison of P2X and TRPV1 receptors in ganglia or primary culture of trigeminal neurons and their modulation by NGF or serotonin

    Directory of Open Access Journals (Sweden)

    Giniatullin Rashid

    2006-03-01

    Full Text Available Abstract Background Cultured sensory neurons are a common experimental model to elucidate the molecular mechanisms of pain transduction typically involving activation of ATP-sensitive P2X or capsaicin-sensitive TRPV1 receptors. This applies also to trigeminal ganglion neurons that convey pain inputs from head tissues. Little is, however, known about the plasticity of these receptors on trigeminal neurons in culture, grown without adding the neurotrophin NGF which per se is a powerful algogen. The characteristics of such receptors after short-term culture were compared with those of ganglia. Furthermore, their modulation by chronically-applied serotonin or NGF was investigated. Results Rat or mouse neurons in culture mainly belonged to small and medium diameter neurons as observed in sections of trigeminal ganglia. Real time RT-PCR, Western blot analysis and immunocytochemistry showed upregulation of P2X3 and TRPV1 receptors after 1–4 days in culture (together with their more frequent co-localization, while P2X2 ones were unchanged. TRPV1 immunoreactivity was, however, lower in mouse ganglia and cultures. Intracellular Ca2+ imaging and whole-cell patch clamping showed functional P2X and TRPV1 receptors. Neurons exhibited a range of responses to the P2X agonist α, β-methylene-adenosine-5'-triphosphate indicating the presence of homomeric P2X3 receptors (selectively antagonized by A-317491 and heteromeric P2X2/3 receptors. The latter were observed in 16 % mouse neurons only. Despite upregulation of receptors in culture, neurons retained the potential for further enhancement of P2X3 receptors by 24 h NGF treatment. At this time point TRPV1 receptors had lost the facilitation observed after acute NGF application. Conversely, chronically-applied serotonin selectively upregulated TRPV1 receptors rather than P2X3 receptors. Conclusion Comparing ganglia and cultures offered the advantage of understanding early adaptive changes of nociception

  7. Environmental phthalate monoesters activate pregnane X receptor-mediated transcription

    International Nuclear Information System (INIS)

    Hurst, Christopher H.; Waxman, David J.

    2004-01-01

    Phthalate esters, widely used as plasticizers in the manufacture of products made of polyvinyl chloride, induce reproductive and developmental toxicities in rodents. The mechanism that underlies these effects of phthalate exposure, including the potential role of members of the nuclear receptor superfamily, is not known. The present study investigates the effects of phthalates on the pregnane X receptor (PXR), which mediates the induction of enzymes involved in steroid metabolism and xenobiotic detoxification. The ability of phthalate monoesters to activate PXR-mediated transcription was assayed in a HepG2 cell reporter assay following transfection with mouse PXR (mPXR), human PXR (hPXR), or the hPXR allelic variants V140M, D163G, and A370T. Mono-2-ethylhexyl phthalate (MEHP) increased the transcriptional activity of both mPXR and hPXR (5- and 15-fold, respectively) with EC 50 values of 7-8 μM. mPXR and hPXR were also activated by monobenzyl phthalate (MBzP, up to 5- to 6-fold) but were unresponsive to monomethyl phthalate and mono-n-butyl phthalate (M(n)BP) at the highest concentrations tested (300 μM). hPXR-V140M and hPXR-A370T exhibited patterns of phthalate responses similar to the wild-type receptor. By contrast, hPXR-D163G was unresponsive to all phthalate monoesters tested. Further studies revealed that hPXR-D163G did respond to rifampicin, but required approximately 40-fold higher concentrations than wild-type receptor, suggesting that the ligand-binding domain D163G variant has impaired ligand-binding activity. The responsiveness of PXR to activation by phthalate monoesters demonstrated here suggests that these ubiquitous environmental chemicals may, in part, exhibit their endocrine disruptor activities by altering PXR-regulated steroid hormone metabolism with potential adverse health effects in exposed individuals

  8. Modulation of the TGF-β1-induced epithelial to mesenchymal transition (EMT) mediated by P1 and P2 purine receptors in MDCK cells.

    Science.gov (United States)

    Zuccarini, Mariachiara; Giuliani, Patricia; Buccella, Silvana; Di Liberto, Valentina; Mudò, Giuseppa; Belluardo, Natale; Carluccio, Marzia; Rossini, Margherita; Condorelli, Daniele Filippo; Rathbone, Michel Piers; Caciagli, Francesco; Ciccarelli, Renata; Di Iorio, Patrizia

    2017-12-01

    Epithelial to mesenchymal transition (EMT) occurs during embryogenesis or under pathological conditions such as hypoxia, injury, chronic inflammation, or tissue fibrosis. In renal tubular epithelial cells (MDCK), TGF-β1 induces EMT by reducing or increasing epithelial or mesenchymal marker expression, respectively. In this study, we confirmed that the cAMP analogues, 8-CPT-cAMP or N6-Ph-cAMP, inhibited the TGF-β1-driven overexpression of the mesenchymal markers ZEB-1, Slug, Fibronectin, and α-SMA. Furthermore, we showed that A1, A2A, P2Y1, P2Y11, and P2X7 purine receptor agonists modulated the TGF-β1-induced EMT through the involvement of PKA and/or MAPK/ERK signaling. The stimulation of A2A receptor reduced the overexpression of the EMT-related markers, mainly through the cAMP-dependent PKA pathway, as confirmed by cell pre-treatment with Myr-PKI. Both A1 and P2Y1 receptor stimulation exacerbated the TGF-β1-driven effects, which were reduced by cell pre-treatment with the MAPK inhibitor PD98059, according to the increased ERK1/2 phosphorylation upon receptor activation. The effects induced by P2Y11 receptor activation were oppositely modulated by PKA or MAPK inhibition, in line with the dual nature of the Gs- and Gq-coupled receptor. Differently, P2X7 receptor induced, per se, similar and not additive effects compared to TGF-β1, after prolonged cell exposure to BzATP. These results suggest a putative role of purine receptors as target for anti-fibrotic agents.

  9. [Trigeminal purinergic P2X4 receptor involved in experimental occlusal interference-induced hyperalgesia in rat masseter muscle].

    Science.gov (United States)

    Xu, Xiaoxiang; Cao, Ye; Ding, Tingting; Fu, Kaiyuan; Xie, Qiufei

    2016-03-01

    To explore the expression of purinergic p2X4 receptor (P2X4R) in trigeminal ganglion of rats after occlusal interference. Investigation of peripheral receptor mechanism of occlusal interference-induced masticatory muscle pain will aid the development of drug intervention against this condition. Experimental occlusal interference was established by application of 0.4 mm metal crown to the upper right first molar of male Sprague-Dawley rats. Real-time PCR assay was used to investigate P2X4R mRNA level in trigeminal ganglion in rats with occlusal interference for 3, 7, 10 and 14 days and in control rats without occlusal interference (n=5 in each). Retrograde labelling combining immunofluorescence was performed to evaluate the percentage of P2X4R-positive cells in masseter afferent neurons (n=5 in each group). Graded concentrations of P2XR antagonist TNP-ATP (0.1, 10, 125, 250, 500 μmol/L) or saline (n=5 in each group) was administrated in right masseter and the mechanical sensitivity of bilateral masseters was measured before occlusal interference application, before the injection, and 30 min as well as 60 min after the injection. Compared with control rats (P2X4R mRNA: right side: 1.00±0.26, left side: 0.94± 0.21; percentage of P2X4R-positive masseter afferents: right side: [64.3±6.3]%, left side: [67.7±5.8]%), the level of P2X4R mRNA in bilateral trigeminal ganglia (right side: 5.98±3.56; left side: 5.06±2.88) of rats with occlusal interference for 7 days up-regulated (Pocclusal interference-induced masseter hyperalgesia.

  10. P2X(3) receptor gating near normal body temperature

    Czech Academy of Sciences Publication Activity Database

    Kmyhz, V.; Maximyuk, O.; Teslenko, V.; Verkhratsky, Alexei; Krishtal, O.

    2008-01-01

    Roč. 456, č. 12 (2008), s. 339-347 ISSN 0031-6768 Institutional research plan: CEZ:AV0Z50390703 Keywords : P2X3 receptors * Temperature-sensitivity * Gating Subject RIV: FH - Neurology Impact factor: 3.526, year: 2008

  11. P2X7 Receptor Antagonism Attenuates the Intermittent Hypoxia-induced Spatial Deficits in a Murine Model of Sleep Apnea Via Inhibiting Neuroinflammation and Oxidative Stress.

    Science.gov (United States)

    Deng, Yan; Guo, Xue-Ling; Yuan, Xiao; Shang, Jin; Zhu, Die; Liu, Hui-Guo

    2015-08-20

    The mechanism of the neural injury caused by chronic intermittent hypoxia (CIH) that characterizes obstructive sleep apnea syndrome (OSAS) is not clearly known. The purpose of this study was to investigate whether P2X7 receptor (P2X7R) is responsible for the CIH-induced neural injury and the possible pathway it involves. Eight-week-old male C57BL/6 mice were used. For each exposure time point, eight mice divided in room air (RA) and IH group were assigned to the study of P2X7R expression. Whereas in the 21 days-Brilliant Blue G (BBG, a selective P2X7R antagonist) study, 48 mice were randomly divided into CIH group, BBG-treated CIH group, RA group and BBG-treated RA group. The hippocampus P2X7R expression was determined by Western blotting and real-time polymerase chain reaction (PCR). The spatial learning was analyzed by Morris water maze. The nuclear factor kappa B (NFκB) and NADPH oxidase 2 (NOX2) expressions were analyzed by Western blotting. The expressions of tumor necrosis factor α, interleukin 1β (IL-β), IL-18, and IL-6 were measured by real-time PCR. The malondialdehyde and superoxide dismutase levels were detected by colorimetric method. Cell damage was evaluated by Hematoxylin and Eosin staining and Terminal Transferase dUTP Nick-end Labeling method. The P2X7R mRNA was elevated and sustained after 3-day IH exposure and the P2X7R protein was elevated and sustained after 7-day IH exposure. In the BBG study, the CIH mice showed severer neuronal cell damage and poorer performance in the behavior test. The increased NFκB and NOX2 expressions along with the inflammation injury and oxidative stress were also observed in the CIH group. BBG alleviated CIH-induced neural injury and consequent functional deficits. The P2X7R antagonism attenuates the CIH-induced neuroinflammation, oxidative stress, and spatial deficits, demonstrating that the P2X7R is an important therapeutic target in the cognition deficits accompanied OSAS.

  12. P2Y receptor-mediated transient relaxation of rat longitudinal ileum preparations involves phospholipase C activation, intracellular Ca(2+) release and SK channel activation.

    Science.gov (United States)

    Mader, Felix; Krause, Ludwig; Tokay, Tursonjan; Hakenberg, Oliver W; Köhling, Rüdiger; Kirschstein, Timo

    2016-05-01

    Purinergic signaling plays a major role in the enteric nervous system, where it governs gut motility through a number of P2X and P2Y receptors. The aim of this study was to investigate the P2Y receptor-mediated motility in rat longitudinal ileum preparations. Ileum smooth muscle strips were prepared from rats, and fixed in an organ bath. Isometric contraction and relaxation responses of the muscle strips were measured with force transducers. Drugs were applied by adding of stock solutions to the organ bath to yield the individual final concentrations. Application of the non-hydrolyzable P2 receptor agonists α,β-Me-ATP or 2-Me-S-ADP (10, 100 μmol/L) dose-dependently elicited a transient relaxation response followed by a sustained contraction. The relaxation response was largely blocked by SK channel blockers apamin (500 nmol/L) and UCL1684 (10 μmol/L), PLC inhibitor U73122 (100 μmol/L), IP3 receptor blocker 2-APB (100 μmol/L) or sarcoendoplasmic Ca(2+) ATPase inhibitor thapsigargin (1 μmol/L), but not affected by atropine, NO synthase blocker L-NAME or tetrodotoxin. Furthermore, α,β-Me-ATP-induced relaxation was suppressed by P2Y1 receptor antagonist MRS2179 (50 μmol/L) or P2Y13 receptor antagonist MRS2211 (100 μmol/L), and was abolished by co-application of the two antagonists, whereas 2-Me-S-ADP-induced relaxation was abolished by P2Y6 receptor antagonist MRS2578 (50 μmol/L). In addition, P2Y1 receptor antagonist MRS2500 (1 μmol/L) not only abolished α,β-Me-ATP-induced relaxation, but also suppressed 2-Me-S-ADP-induced relaxation. P2Y receptor agonist-induced transient relaxation of rat ileum smooth muscle strips is mediated predominantly by P2Y1 receptor, but also by P2Y6 and P2Y13 receptors, and involves PLC, IP3, Ca(2+) release and SK channel activation, but is independent of acetylcholine and NO release.

  13. P2X7 receptor inhibition increases CNTF in the subventricular zone, but not neurogenesis or neuroprotection after stroke in adult mice.

    Science.gov (United States)

    Kang, Seong Su; Keasey, Matthew Phillip; Hagg, Theo

    2013-10-01

    Increasing endogenous ciliary neurotrophic factor (CNTF) expression with a pharmacological agent might be beneficial after stroke as CNTF both promotes neurogenesis and, separately, is neuroprotective. P2X7 purinergic receptor inhibition is neuroprotective in rats and increases CNTF release in rat CMT1A Schwann cells. We, first, investigated the role of P2X7 in regulating CNTF and neurogenesis in adult mouse subventricular zone (SVZ). CNTF expression was increased by daily intravenous injections of the P2X7 antagonist Brilliant Blue G (BBG) in naïve C57BL/6 or Balb/c mice over 3 days. Despite the ∼40-60 % increase or decrease in CNTF with BBG or the agonist BzATP, respectively, the number of proliferated BrdU+SVZ nuclei did not change. BBG failed to increase FGF2, which is involved in CNTF-regulated neurogenesis, but induced IL-6, LIF, and EGF, which are known to reduce SVZ proliferation. Injections of IL-6 next to the SVZ induced CNTF and FGF2, but not proliferation, suggesting that IL-6 counteracts their neurogenesis-inducing effects. Following ischemic injury of the striatum by middle cerebral artery occlusion (MCAO), a 3-day BBG treatment increased CNTF in the medial penumbra containing the SVZ. BBG also induced CNTF and LIF, which are known to be protective following stroke, in the whole striatum after MCAO, but not GDNF or BDNF. However, BBG treatment did not reduce the lesion area or apoptosis in the penumbra. Even so, this study shows that P2X7 can be targeted with systemic drug treatments to differentially regulate neurotrophic factors in the brain following stroke.

  14. The scaffold protein calcium/calmodulin-dependent serine protein kinase controls ATP release in sensory ganglia upon P2X3 receptor activation and is part of an ATP keeper complex.

    Science.gov (United States)

    Bele, Tanja; Fabbretti, Elsa

    2016-08-01

    P2X3 receptors, gated by extracellular ATP, are expressed by sensory neurons and are involved in peripheral nociception and pain sensitization. The ability of P2X3 receptors to transduce extracellular stimuli into neuronal signals critically depends on the dynamic molecular partnership with the calcium/calmodulin-dependent serine protein kinase (CASK). The present work used trigeminal sensory neurons to study the impact that activation of P2X3 receptors (evoked by the agonist α,β-meATP) has on the release of endogenous ATP and how CASK modulates this phenomenon. P2X3 receptor function was followed by ATP efflux via Pannexin1 (Panx1) hemichannels, a mechanism that was blocked by the P2X3 receptor antagonist A-317491, and by P2X3 silencing. ATP efflux was enhanced by nerve growth factor, a treatment known to potentiate P2X3 receptor function. Basal ATP efflux was not controlled by CASK, and carbenoxolone or Pannexin silencing reduced ATP release upon P2X3 receptor function. CASK-controlled ATP efflux followed P2X3 receptor activity, but not depolarization-evoked ATP release. Molecular biology experiments showed that CASK was essential for the transactivation of Panx1 upon P2X3 receptor activation. These data suggest that P2X3 receptor function controls a new type of feed-forward purinergic signaling on surrounding cells, with consequences at peripheral and spinal cord level. Thus, P2X3 receptor-mediated ATP efflux may be considered for the future development of pharmacological strategies aimed at containing neuronal sensitization. P2X3 receptors are involved in sensory transduction and associate to CASK. We have studied in primary sensory neurons the molecular mechanisms downstream P2X3 receptor activation, namely ATP release and partnership with CASK or Panx1. Our data suggest that CASK and P2X3 receptors are part of an ATP keeper complex, with important feed-forward consequences at peripheral and central level. © 2016 International Society for Neurochemistry.

  15. Functional characterization of mutants in the transmembrane domains of the rat P2X7 receptor that regulate pore conductivity and agonist sensitivity

    Czech Academy of Sciences Publication Activity Database

    Jindřichová, Marie; Bhattacharya, Anirban; Rupert, Marian; Škopek, Petr; Obšil, T.; Zemková, Hana

    2015-01-01

    Roč. 133, č. 6 (2015), s. 815-827 ISSN 0022-3042 R&D Projects: GA ČR(CZ) GPP304/12/P371; GA ČR(CZ) GBP304/12/G069; GA MŠk(CZ) EE2.3.30.0025; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:67985823 Keywords : ATP * purinergic receptor channel * P2X7 * pore dilation * YO-PRO-1 uptake Subject RIV: ED - Physiology Impact factor: 3.842, year: 2015

  16. The therapeutic promise of ATP antagonism at P2X3 receptors in respiratory & urological disorders

    Directory of Open Access Journals (Sweden)

    Anthony eFord

    2013-12-01

    Full Text Available A sensory role for ATP was proposed long before general acceptance of its extracellular role. ATP activates & sensitizes signal transmission at multiple sites along the sensory axis, across multiple synapses. P2X & P2Y receptors mediate ATP modulation of sensory pathways & participate in dysregulation, where ATP action directly on primary afferent neurons (PANs, linking receptive field to CNS, has received much attention. Many PANs, especially C-fibers, are activated by ATP, via P2X3-containing trimers. P2X3 knock-out mice & knock-down in rats led to reduced nocifensive activity & visceral reflexes, suggesting that antagonism may offer benefit in sensory disorders. Recently, drug-like P2X3 antagonists, active in a many inflammatory & visceral pain models, have emerged. Significantly, these compounds have no overt CNS action & are inactive versus acute nociception. Selectively targeting ATP sensitization of PANs may lead to therapies that block inappropriate chronic signals at their source, decreasing drivers of peripheral & central wind-up, yet leaving defensive nociceptive and brain functions unperturbed. This article reviews this evidence, focusing on how ATP sensitization of PANs in visceral hollow organs primes them to chronic discomfort, irritation & pain (symptoms as well as exacerbated autonomic reflexes (signs, & how the use of isolated organ-nerve preparations has revealed this mechanism. Urinary & airways systems share many features: dependence on continuous afferent traffic to brainstem centers to coordinate efferent autonomic outflow; loss of descending inhibitory influence in functional & sensory disorders; dependence on ATP in mediating sensory responses to diverse mechanical and chemical stimuli; a mechanistically overlapping array of existing medicines for pathological conditions. These similarities may also play out in terms of future treatment of signs & symptoms, in the potential for benefit of P2X3 antagonists.

  17. ATP induces NO production in hippocampal neurons by P2X(7 receptor activation independent of glutamate signaling.

    Directory of Open Access Journals (Sweden)

    Juan Francisco Codocedo

    Full Text Available To assess the putative role of adenosine triphosphate (ATP upon nitric oxide (NO production in the hippocampus, we used as a model both rat hippocampal slices and isolated hippocampal neurons in culture, lacking glial cells. In hippocampal slices, additions of exogenous ATP or 2'(3'-O-(4-Benzoylbenzoyl ATP (Bz-ATP elicited concentration-dependent NO production, which increased linearly within the first 15 min and plateaued thereafter; agonist EC50 values were 50 and 15 µM, respectively. The NO increase evoked by ATP was antagonized in a concentration-dependent manner by Coomassie brilliant blue G (BBG or by N(ω-propyl-L-arginine, suggesting the involvement of P2X7Rs and neuronal NOS, respectively. The ATP induced NO production was independent of N-methyl-D-aspartic acid (NMDA receptor activity as effects were not alleviated by DL-2-Amino-5-phosphonopentanoic acid (APV, but antagonized by BBG. In sum, exogenous ATP elicited NO production in hippocampal neurons independently of NMDA receptor activity.

  18. Opposing Roles of Calcium and Intracellular ATP on Gating of the Purinergic P2X2 Receptor Channel

    Directory of Open Access Journals (Sweden)

    Milos B. Rokic

    2018-04-01

    Full Text Available P2X2 receptors (P2X2R exhibit a slow desensitization during the initial ATP application and a progressive, calcium-dependent increase in rates of desensitization during repetitive stimulation. This pattern is observed in whole-cell recordings from cells expressing recombinant and native P2X2R. However, desensitization is not observed in perforated-patched cells and in two-electrode voltage clamped oocytes. Addition of ATP, but not ATPγS or GTP, in the pipette solution also abolishes progressive desensitization, whereas intracellular injection of apyrase facilitates receptor desensitization. Experiments with injection of alkaline phosphatase or addition of staurosporine and ATP in the intracellular solution suggest a role for a phosphorylation-dephosphorylation in receptor desensitization. Mutation of residues that are potential phosphorylation sites identified a critical role of the S363 residue in the intracellular ATP action. These findings indicate that intracellular calcium and ATP have opposing effects on P2X2R gating: calcium allosterically facilitates receptor desensitization and ATP covalently prevents the action of calcium. Single cell measurements further revealed that intracellular calcium stays elevated after washout in P2X2R-expressing cells and the blockade of mitochondrial sodium/calcium exchanger lowers calcium concentrations during washout periods to basal levels, suggesting a role of mitochondria in this process. Therefore, the metabolic state of the cell can influence P2X2R gating.

  19. Neuropharmacology of purinergic receptors in human submucous plexus: Involvement of P2X₁, P2X₂, P2X₃ channels, P2Y and A₃ metabotropic receptors in neurotransmission.

    Science.gov (United States)

    Liñán-Rico, A; Wunderlich, J E; Enneking, J T; Tso, D R; Grants, I; Williams, K C; Otey, A; Michel, K; Schemann, M; Needleman, B; Harzman, A; Christofi, F L

    2015-08-01

    The role of purinergic signaling in human ENS is not well understood. We sought to further characterize the neuropharmacology of purinergic receptors in human ENS and test the hypothesis that endogenous purines are critical regulators of neurotransmission. LSCM-Fluo-4/(Ca(2+))-imaging of postsynaptic Ca(2+) transients (PSCaTs) was used as a reporter of synaptic transmission evoked by fiber tract electrical stimulation in human SMP surgical preparations. Pharmacological analysis of purinergic signaling was done in 1,556 neurons (identified by HuC/D-immunoreactivity) in 235 ganglia from 107 patients; P2XR-immunoreactivity was evaluated in 19 patients. Real-time MSORT (Di-8-ANEPPS) imaging tested effects of adenosine on fast excitatory synaptic potentials (fEPSPs). Synaptic transmission is sensitive to pharmacological manipulations that alter accumulation of extracellular purines: Apyrase blocks PSCaTs in a majority of neurons. An ecto-NTPDase-inhibitor 6-N,N-diethyl-D-β,γ-dibromomethyleneATP or adenosine deaminase augments PSCaTs. Blockade of reuptake/deamination of eADO inhibits PSCaTs. Adenosine inhibits fEPSPs and PSCaTs (IC50 = 25 µM), sensitive to MRS1220-antagonism (A3AR). A P2Y agonist ADPβS inhibits PSCaTs (IC50 = 111 nM) in neurons without stimulatory ADPbS responses (EC50 = 960 nM). ATP or a P2X1,2,2/3 (α,β-MeATP) agonist evokes fast, slow, biphasic Ca(2+) transients or Ca(2+) oscillations (ATP,EC50 = 400 mM). PSCaTs are sensitive to P2X1 antagonist NF279. Low (20 nM) or high (5 µM) concentrations of P2X antagonist TNP-ATP block PSCaTs in different neurons; proportions of neurons with P2XR-immunoreactivity follow the order P2X2 > P2X1 > P2X3; P2X1 + P2X2 and P2X3 + P2X2 are co-localized. RT-PCR identified mRNA-transcripts for P2X1-7, P2Y1,2,12-14R. Purines are critical regulators of neurotransmission in human ENS. Purinergic signaling involves P2X1, P2X2, P2X3 channels, P2X1 + P2X2 co-localization and inhibitory P2Y or A3 receptors. These are

  20. P2X₇ receptor of rat dorsal root ganglia is involved in the effect of moxibustion on visceral hyperalgesia.

    Science.gov (United States)

    Liu, Shuangmei; Shi, Qingming; Zhu, Qicheng; Zou, Ting; Li, Guilin; Huang, An; Wu, Bing; Peng, Lichao; Song, Miaomiao; Wu, Qin; Xie, Qiuyu; Lin, Weijian; Xie, Wei; Wen, Shiyao; Zhang, Zhedong; Lv, Qiulan; Zou, Lifang; Zhang, Xi; Ying, Mofeng; Li, Guodong; Liang, Shangdong

    2015-06-01

    Irritable bowel syndrome (IBS) and inflammatory bowel disease often display visceral hypersensitivity. Visceral nociceptors after inflammatory stimulation generate afferent nerve impulses through dorsal root ganglia (DRG) transmitting to the central nervous system. ATP and its activated-purinergic 2X7 (P2X7) receptor play an important role in the transmission of nociceptive signal. Purinergic signaling is involved in the sensory transmission of visceral pain. Moxibustion is a therapy applying ignited mugwort directly or indirectly at acupuncture points or other specific parts of the body to treat diseases. Heat-sensitive acupoints are the corresponding points extremely sensitive to moxa heat in disease conditions. In this study, we aimed to investigate the relationship between the analgesic effect of moxibustion on a heat-sensitive acupoint "Dachangshu" and the expression levels of P2X7 receptor in rat DRG after chronic inflammatory stimulation of colorectal distension. Heat-sensitive moxibustion at Dachangshu acupoint inhibited the nociceptive signal transmission by decreasing the upregulated expression levels of P2X7 mRNA and protein in DRG induced by visceral pain, and reversed the abnormal expression of glial fibrillary acidic protein (GFAP, a marker of satellite glial cells) in DRG. Consequently, abdominal withdrawal reflex (AWR) score in a visceral pain model was reduced, and the pain threshold was elevated. Therefore, heat-sensitive moxibustion at Dachangshu acupoint can produce a therapeutic effect on IBS via inhibiting the nociceptive transmission mediated by upregulated P2X7 receptor.

  1. Association of occlusal interference-induced masseter muscle hyperalgesia and P2X3 receptors in the trigeminal subnucleus caudalis and midbrain periaqueductal gray.

    Science.gov (United States)

    Sun, Shuzhen; Qi, Dong; Yang, Yingying; Ji, Ping; Kong, Jingjing; Wu, Qingting

    2016-03-02

    P2X3 receptor plays a role in nociception transmission of orofacial pain in temporomandibular disorder patients. A previous study found that P2X3 receptors in masseter muscle afferent neurons and the trigeminal ganglia were involved in masseter muscle pain induced by inflammation caused by chemical agents or eccentric muscle contraction. In this study, we attempted to investigate changes in P2X3 receptors in the trigeminal subnucleus caudalis (Vc) and midbrain periaqueductal gray (PAG) in relation to the hyperalgesia of masseter muscles induced by occlusal interference. Experimental occlusal interference by crown application was established in 30 rats and another 30 rats were treated as sham controls. On days 1, 3, 7, 14, and 28 after crown application, the mechanical pain threshold was examined by von-Frey filaments. The expression of the P2X3 receptor in Vc and PAG was investigated by immunohistochemistry and quantitative PCR. We found that mechanical pain threshold of bilateral masseter muscles decreased significantly after occlusal interference, which remained for the entire experimental period. The mRNA expression of the P2X3 receptor increased significantly and the number of P2X3R-positive neurons increased markedly in Vc and PAG accordingly. These results indicate that the upregulated expression of P2X3 receptors in Vc and PAG may contribute toward the development of orofacial pain induced by occlusal interference and P2X3 receptors in the PAG may play a key role in the supraspinal antiociception effect.

  2. Polymorphisms in the P2X7 receptor gene are associated with low lumbar spine bone mineral density and accelerated bone loss in post-menopausal women

    DEFF Research Database (Denmark)

    Gartland, Alison; Skarratt, Kristen K; Hocking, Lynne J

    2012-01-01

    The P2X7 receptor gene (P2RX7) is highly polymorphic with five previously described loss-of-function (LOF) single-nucleotide polymorphisms (SNP; c.151+1G>T, c.946G>A, c.1096C>G, c.1513A>C and c.1729T>A) and one gain-of-function SNP (c.489C>T). The purpose of this study was to determine whether th...... publication, 11 January 2012; doi:10.1038/ejhg.2011.245....

  3. Variable transcriptional responsiveness of the P2X3 receptor gene during CFA-induced inflammatory hyperalgesia.

    Science.gov (United States)

    Nuñez-Badinez, Paulina; Sepúlveda, Hugo; Diaz, Emilio; Greffrath, Wolfgang; Treede, Rolf-Detlef; Stehberg, Jimmy; Montecino, Martin; van Zundert, Brigitte

    2018-05-01

    The purinergic receptor P2X3 (P2X3-R) plays important roles in molecular pathways of pain, and reduction of its activity or expression effectively reduces chronic inflammatory and neuropathic pain sensation. Inflammation, nerve injury, and cancer-induced pain can increase P2X3-R mRNA and/or protein levels in dorsal root ganglia (DRG). However, P2X3-R expression is unaltered or even reduced in other pain studies. The reasons for these discrepancies are unknown and might depend on the applied traumatic intervention or on intrinsic factors such as age, gender, genetic background, and/or epigenetics. In this study, we sought to get insights into the molecular mechanisms responsible for inflammatory hyperalgesia by determining P2X3-R expression in DRG neurons of juvenile male rats that received a Complete Freund's Adjuvant (CFA) bilateral paw injection. We demonstrate that all CFA-treated rats showed inflammatory hyperalgesia, however, only a fraction (14-20%) displayed increased P2X3-R mRNA levels, reproducible across both sides. Immunostaining assays did not reveal significant increases in the percentage of P2X3-positive neurons, indicating that increased P2X3-R at DRG somas is not critical for inducing inflammatory hyperalgesia in CFA-treated rats. Chromatin immunoprecipitation (ChIP) assays showed a correlated (R 2  = 0.671) enrichment of the transcription factor Runx1 and the epigenetic active mark histone H3 acetylation (H3Ac) at the P2X3-R gene promoter in a fraction of the CFA-treated rats. These results suggest that animal-specific increases in P2X3-R mRNA levels are likely associated with the genetic/epigenetic context of the P2X3-R locus that controls P2X3-R gene transcription by recruiting Runx1 and epigenetic co-regulators that mediate histone acetylation. © 2017 Wiley Periodicals, Inc.

  4. Peripheral and central P2X3 receptor contributions to colon mechanosensitivity and hypersensitivity in the mouse

    Science.gov (United States)

    Shinoda, Masamichi; Feng, Bin; Gebhart, G. F.

    2009-01-01

    Background & Aims Irritable bowel syndrome is characterized by altered sensory qualities, namely discomfort/pain and colorectal hypersensitivity. In mice, we examined the role of P2X3 receptors in colon mechanosensitivity and intracolonic zymosan-produced hypersensitivity, a model of persistent colon hypersensitivity without colon inflammation. Methods The visceromotor response (VMR) to colon distension (15 – 60 mmHg) was determined before and after intracolonic saline or zymosan (30 mg/mL, 0.1 mL, daily for 3 days) treatment. Colon pathology and intracolonic ATP release was assessed in parallel experiments. To examine P2X3 receptor contributions to colon mechanosensation and hypersensitivity, electrophysiological experiments were performed using an in vitro colon-pelvic nerve preparation. Results VMRs to distension were significantly reduced in P2X3+/−and P2X3−/− mice relative to wildtype mice. Colon hypersensitivity produced by zymosan was virtually absent in P2X3−/− relative to wildtype or P2X3+/− mice. Intralumenal release of the endogenous P2X receptor ligand ATP did not differ between wildtype and P2X3−/− mice or change after intracolonic zymosan treatment. Responses of muscular and muscular-mucosal pelvic nerve afferents to mechanical stretch did not differ between P2X3−/− and wildtype mice. Both muscular and muscular-mucosal afferents in wildtype mice sensitized to application of an inflammatory soup, whereas only muscular-mucosal afferents did so in P2X3−/− mice. Conclusions These results suggest differential roles for peripheral and central P2X3 receptors in colon mechanosensory transduction and hypersensitivity. PMID:19549524

  5. Spinal cord pathology is ameliorated by P2X7 antagonism in a SOD1-mutant mouse model of amyotrophic lateral sclerosis

    Directory of Open Access Journals (Sweden)

    Savina Apolloni

    2014-09-01

    Full Text Available In recent years there has been an increasing awareness of the role of P2X7, a receptor for extracellular ATP, in modulating physiopathological mechanisms in the central nervous system. In particular, P2X7 has been shown to be implicated in neuropsychiatry, chronic pain, neurodegeneration and neuroinflammation. Remarkably, P2X7 has also been shown to be a ‘gene modifier’ in amyotrophic lateral sclerosis (ALS: the receptor is upregulated in spinal cord microglia in human and rat at advanced stages of the disease; in vitro, activation of P2X7 exacerbates pro-inflammatory responses in microglia that have an ALS phenotype, as well as toxicity towards neuronal cells. Despite this detrimental in vitro role of P2X7, in SOD1-G93A mice lacking P2X7, the clinical onset of ALS was significantly accelerated and disease progression worsened, thus indicating that the receptor might have some beneficial effects, at least at certain stages of disease. In order to clarify this dual action of P2X7 in ALS pathogenesis, in the present work we used the antagonist Brilliant Blue G (BBG, a blood-brain barrier permeable and safe drug that has already been proven to reduce neuroinflammation in traumatic brain injury, cerebral ischemia-reperfusion, neuropathic pain and experimental autoimmune encephalitis. We tested BBG in the SOD1-G93A ALS mouse model at asymptomatic, pre-symptomatic and late pre-symptomatic phases of disease. BBG at late pre-onset significantly enhanced motor neuron survival and reduced microgliosis in lumbar spinal cord, modulating inflammatory markers such as NF-κB, NADPH oxidase 2, interleukin-1β, interleukin-10 and brain-derived neurotrophic factor. This was accompanied by delayed onset and improved general conditions and motor performance, in both male and female mice, although survival appeared unaffected. Our results prove the twofold role of P2X7 in the course of ALS and establish that P2X7 modulation might represent a promising

  6. Interaction of medullary P2 and glutamate receptors mediates the vasodilation in the hindlimb of rat.

    Science.gov (United States)

    Korim, Willian Seiji; Ferreira-Neto, Marcos L; Pedrino, Gustavo R; Pilowsky, Paul M; Cravo, Sergio L

    2012-12-01

    In the nucleus tractus solitarii (NTS) of rats, blockade of extracellular ATP breakdown to adenosine reduces arterial blood pressure (AP) increases that follow stimulation of the hypothalamic defense area (HDA). The effects of ATP on NTS P2 receptors, during stimulation of the HDA, are still unclear. The aim of this study was to determine whether activation of P2 receptors in the NTS mediates cardiovascular responses to HDA stimulation. Further investigation was taken to establish if changes in hindlimb vascular conductance (HVC) elicited by electrical stimulation of the HDA, or activation of P2 receptors in the NTS, are relayed in the rostral ventrolateral medulla (RVLM); and if those responses depend on glutamate release by ATP acting on presynaptic terminals. In anesthetized and paralyzed rats, electrical stimulation of the HDA increased AP and HVC. Blockade of P2 or glutamate receptors in the NTS, with bilateral microinjections of suramin (10 mM) or kynurenate (50 mM) reduced only the evoked increase in HVC by 75 % or more. Similar results were obtained with the blockade combining both antagonists. Blockade of P2 and glutamate receptors in the RVLM also reduced the increases in HVC to stimulation of the HDA by up to 75 %. Bilateral microinjections of kynurenate in the RVLM abolished changes in AP and HVC to injections of the P2 receptor agonist α,β-methylene ATP (20 mM) into the NTS. The findings suggest that HDA-NTS-RVLM pathways in control of HVC are mediated by activation of P2 and glutamate receptors in the brainstem in alerting-defense reactions.

  7. Tet1 and Tet2 maintain mesenchymal stem cell homeostasis via demethylation of the P2rX7 promoter.

    Science.gov (United States)

    Yang, Ruili; Yu, Tingting; Kou, Xiaoxing; Gao, Xiang; Chen, Chider; Liu, Dawei; Zhou, Yanheng; Shi, Songtao

    2018-06-01

    Ten-eleven translocation (Tet) family-mediated DNA oxidation represents an epigenetic modification capable of converting 5-methylcytosine (5-mC) to 5-hydroxymethylcytosine (5-hmC), which regulates various biological processes. However, it is unknown whether Tet family affects mesenchymal stem cells (MSCs) or the skeletal system. Here we show that depletion of Tet1 and Tet2 results in impaired self-renewal and differentiation of bone marrow MSCs (BMMSCs) and a significant osteopenia phenotype. Tet1 and Tet2 deficiency reduces demethylation of the P2rX7 promoter and downregulates exosome release, leading to intracellular accumulation of miR-297a-5p, miR-297b-5p, and miR-297c-5p. These miRNAs inhibit Runx2 signaling to impair BMMSC function. We show that overexpression of P2rX7 rescues the impaired BMMSCs and osteoporotic phenotype in Tet1 and Tet2 double knockout mice. These results indicate that Tet1 and Tet2 play a critical role in maintaining BMMSC and bone homeostasis through demethylation of P2rX7 to control exosome and miRNA release. This Tet/P2rX7/Runx2 cascade may serve as a target for the development of novel therapies for osteopenia disorders.

  8. Single nucleotide polymorphisms in the P2X7 gene are associated to fracture risk and to effect of estrogen treatment

    DEFF Research Database (Denmark)

    Ohlendorff, Stine D; Tofteng, Charlotte L; Jensen, Jens-Erik B

    2007-01-01

    OBJECTIVES: The purinergic P2RX7 receptor (P2RX7) has been shown to play a role in the regulation of osteoblast and osteoclast activity. The aim of this study was to determine the presence of polymorphisms in exon 13 of the P2X7 gene and the association with osteoclast apoptosis in vitro and bone...

  9. The Cellular Prion Protein Prevents Copper-Induced Inhibition of P2X4 Receptors

    Directory of Open Access Journals (Sweden)

    Ramón A. Lorca

    2011-01-01

    Full Text Available Although the physiological function of the cellular prion protein (PrPC remains unknown, several evidences support the notion of its role in copper homeostasis. PrPC binds Cu2+ through a domain composed by four to five repeats of eight amino acids. Previously, we have shown that the perfusion of this domain prevents and reverses the inhibition by Cu2+ of the adenosine triphosphate (ATP-evoked currents in the P2X4 receptor subtype, highlighting a modulatory role for PrPC in synaptic transmission through regulation of Cu2+ levels. Here, we study the effect of full-length PrPC in Cu2+ inhibition of P2X4 receptor when both are coexpressed. PrPC expression does not significantly change the ATP concentration-response curve in oocytes expressing P2X4 receptors. However, the presence of PrPC reduces the inhibition by Cu2+ of the ATP-elicited currents in these oocytes, confirming our previous observations with the Cu2+ binding domain. Thus, our observations suggest a role for PrPC in modulating synaptic activity through binding of extracellular Cu2+.

  10. Single nucleotide polymorphisms in the P2X7 gene are associated to fracture risk and to effect of estrogen treatment

    DEFF Research Database (Denmark)

    Ohlendorff, Stine D; Tofteng, Charlotte L; Jensen, Jens-Erik B

    2007-01-01

    The purinergic P2RX7 receptor (P2RX7) has been shown to play a role in the regulation of osteoblast and osteoclast activity. The aim of this study was to determine the presence of polymorphisms in exon 13 of the P2X7 gene and the association with osteoclast apoptosis in vitro and bone status in v...

  11. Deciphering the regulation of P2X4 receptor channel gating by ivermectin using Markov models.

    Directory of Open Access Journals (Sweden)

    Laurent Mackay

    2017-07-01

    Full Text Available The P2X4 receptor (P2X4R is a member of a family of purinergic channels activated by extracellular ATP through three orthosteric binding sites and allosterically regulated by ivermectin (IVM, a broad-spectrum antiparasitic agent. Treatment with IVM increases the efficacy of ATP to activate P2X4R, slows both receptor desensitization during sustained ATP application and receptor deactivation after ATP washout, and makes the receptor pore permeable to NMDG+, a large organic cation. Previously, we developed a Markov model based on the presence of one IVM binding site, which described some effects of IVM on rat P2X4R. Here we present two novel models, both with three IVM binding sites. The simpler one-layer model can reproduce many of the observed time series of evoked currents, but does not capture well the short time scales of activation, desensitization, and deactivation. A more complex two-layer model can reproduce the transient changes in desensitization observed upon IVM application, the significant increase in ATP-induced current amplitudes at low IVM concentrations, and the modest increase in the unitary conductance. In addition, the two-layer model suggests that this receptor can exist in a deeply inactivated state, not responsive to ATP, and that its desensitization rate can be altered by each of the three IVM binding sites. In summary, this study provides a detailed analysis of P2X4R kinetics and elucidates the orthosteric and allosteric mechanisms regulating its channel gating.

  12. Functional and molecular evidence for heteromeric association of P2Y1 receptor with P2Y2 and P2Y4 receptors in mouse granulocytes.

    Science.gov (United States)

    Ribeiro-Filho, Antonio Carlos; Buri, Marcus Vinicius; Barros, Carlos Castilho; Dreyfuss, Juliana Luporini; Nader, Helena Bonciani; Justo, Giselle Zenker; Craveiro, Rogério Bastos; Pesquero, João Bosco; Miranda, Antonio; Ferreira, Alice Teixeira; Paredes-Gamero, Edgar Julian

    2016-07-07

    All hematopoietic cells express P2 receptors, however pharmacological characteristics such as expression and affinity in granulocytes are unknown. Pharmacological characteristics of P2 receptors were evaluated by Ca(2+) measurements using Fura-2 fluorophore. P2 receptors expression were analyzed by flow cytometry and RT-PCR. P2 interaction were shown by coimmunoprecipitation, western blotting and FRET. Granulocytes were responsive to P2Y agonists, whereas P2X agonists were ineffective. Ca(2+) increase, elicited by ADP and UTP was dependent on intracellular stocks and sensitive to G-coupled receptor inhibition. Moreover, MRS2179, a specific antagonist of the P2Y1 receptor, abolished ADP response. Interestingly, ADP and UTP exhibited full heterologous desensitization, suggesting that these agonists interact with the same receptor. The heteromeric association between P2Y1 receptor and the P2Y2 and P2Y4 receptors was shown by immunoprecipitation and FRET analysis. Clear evidence of heteromeric association of P2Y receptors was found during the evaluation of P2 receptors present in mice granulocytes, which could impact in the classical pharmacology of P2Y receptors in granulocytes.

  13. Effect of ATP on intracellular pH in pancreatic ducts involves P2X7 receptors

    DEFF Research Database (Denmark)

    Henriksen, Katerine L; Novak, Ivana

    2003-01-01

    which P2 receptors might be involved. Ducts were obtained from rat pancreas, and the pH sensitive fluorophore BCECF was used to measure pHi and recovery rates from cellular acidosis induced by ammonium pre-pulses. In order to reveal Na+/H+ exchange, Cl-/HCO3- exchange or a Na+-HCO3- cotransport...

  14. Role of peripheral sigma-1 receptors in ischaemic pain: Potential interactions with ASIC and P2X receptors.

    Science.gov (United States)

    Kwon, S G; Roh, D H; Yoon, S Y; Choi, S R; Choi, H S; Moon, J Y; Kang, S Y; Kim, H W; Han, H J; Beitz, A J; Oh, S B; Lee, J H

    2016-04-01

    The role of peripheral sigma-1 receptors (Sig-1Rs) in normal nociception and in pathologically induced pain conditions has not been thoroughly investigated. Since there is mounting evidence that Sig-1Rs modulate ischaemia-induced pathological conditions, we investigated the role of Sig-1Rs in ischaemia-induced mechanical allodynia (MA) and addressed their possible interaction with acid-sensing ion channels (ASICs) and P2X receptors at the ischaemic site. We used a rodent model of hindlimb thrombus-induced ischaemic pain (TIIP) to investigate their role. Western blot was performed to observe changes in Sig-1R expression in peripheral nervous tissues. MA was measured after intraplantar (i.pl.) injections of antagonists for the Sig-1, ASIC and P2X receptors in TIIP rats or agonists of each receptor in naïve rats. Sig-1R expression significantly increased in skin, sciatic nerve and dorsal root ganglia at 3 days post-TIIP surgery. I.pl. injections of the Sig-1R antagonist, BD-1047 on post-operative days 0-3 significantly attenuated the development of MA during the induction phase, but had no effect on MA when given during the maintenance phase (days 3-6 post-surgery). BD-1047 synergistically increased amiloride (an ASICs blocker)- and TNP-ATP (a P2X antagonist)-induced analgesic effects in TIIP rats. In naïve rats, i.pl. injection of Sig-1R agonist PRE-084 alone did not produce MA; but it did induce MA when co-administered with either an acidic pH solution or a sub-effective dose of αβmeATP. Peripheral Sig-1Rs contribute to the induction of ischaemia-induced MA via facilitation of ASICs and P2X receptors. Thus, peripheral Sig-1Rs represent a novel therapeutic target for the treatment of ischaemic pain. © 2015 European Pain Federation - EFIC®

  15. Protein kinase C-mediated ATP stimulation of Na(+)-ATPase activity in LLC-PK1 cells involves a P2Y2 and/or P2Y4 receptor.

    Science.gov (United States)

    Wengert, M; Ribeiro, M C; Abreu, T P; Coutinho-Silva, R; Leão-Ferreira, L R; Pinheiro, A A S; Caruso-Neves, C

    2013-07-15

    ATP-activated P2Y receptors play an important role in renal sodium excretion. The aim of this study was to evaluate the modulation of ATPase-driven sodium reabsorption in the proximal tubule by ATP or adenosine (Ado). LLC-PK1 cells, a model of porcine proximal tubule cells, were used. ATP (10(-6)M) or Ado (10(-6)M) specifically stimulated Na(+)-ATPase activity without any changes in (Na(+)+K(+))-ATPase activity. Our results show that the Ado effect is mediated by its conversion to ATP. Furthermore, it was observed that the effect of ATP was mimicked by UTP, ATPγS and 2-thio-UTP, an agonist of P2Y2 and P2Y4 receptors. In addition, ATP-stimulated Na(+)-ATPase activity involves protein kinase C (PKC). Our results indicate that ATP-induced stimulation of proximal tubule Na(+)-ATPase activity is mediated by a PKC-dependent P2Y2 and/or P2Y4 pathway. These findings provide new perspectives on the role of the effect of P2Y-mediated extracellular ATP on renal sodium handling. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Role of P2 Receptors as Modulators of Rat Eosinophil Recruitment in Allergic Inflammation.

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    Anael Viana Pinto Alberto

    Full Text Available ATP and other nucleotides are released from cells through regulated pathways or following the loss of plasma membrane integrity. Once outside the cell, these compounds can activate P2 receptors: P2X ionotropic receptors and G protein-coupled P2Y receptors. Eosinophils represent major effector cells in the allergic inflammatory response and they are, in fact, associated with several physiological and pathological processes. Here we investigate the expression of P2 receptors and roles of those receptors in murine eosinophils. In this context, our first step was to investigate the expression and functionality of the P2X receptors by patch clamping, our results showed a potency ranking order of ATP>ATPγS> 2meSATP> ADP> αβmeATP> βγmeATP>BzATP> UTP> UDP>cAMP. This data suggest the presence of P2X1, P2X2 and P2X7. Next we evaluate by microfluorimetry the expression of P2Y receptors, our results based in the ranking order of potency (UTP>ATPγS> ATP > UDP> ADP >2meSATP > αβmeATP suggests the presence of P2Y2, P2Y4, P2Y6 and P2Y11. Moreover, we confirmed our findings by immunofluorescence assays. We also did chemotaxis assays to verify whether nucleotides could induce migration. After 1 or 2 hours of incubation, ATP increased migration of eosinophils, as well as ATPγS, a less hydrolysable analogue of ATP, while suramin a P2 blocker abolished migration. In keeping with this idea, we tested whether these receptors are implicated in the migration of eosinophils to an inflammation site in vivo, using a model of rat allergic pleurisy. In fact, migration of eosinophils has increased when ATP or ATPγS were applied in the pleural cavity, and once more suramin blocked this effect. We have demonstrated that rat eosinophils express P2X and P2Y receptors. In addition, the activation of P2 receptors can increase migration of eosinophils in vitro and in vivo, an effect blocked by suramin.

  17. P2X7 Cell Death Receptor Activation and Mitochondrial Impairment in Oxaliplatin-Induced Apoptosis and Neuronal Injury: Cellular Mechanisms and In Vivo Approach.

    Directory of Open Access Journals (Sweden)

    France Massicot

    Full Text Available Limited information is available regarding the cellular mechanisms of oxaliplatin-induced painful neuropathy during exposure of patients to this drug. We therefore determined oxidative stress in cultured cells and evaluated its occurrence in C57BL/6 mice. Using both cultured neuroblastoma (SH-SY5Y and macrophage (RAW 264.7 cell lines and also brain tissues of oxaliplatin-treated mice, we investigated whether oxaliplatin (OXA induces oxidative stress and apoptosis. Cultured cells were treated with 2-200 µM OXA for 24 h. The effects of pharmacological inhibitors of oxidative stress or inflammation (N-acetyl cysteine, ibuprofen, acetaminophen were also tested. Inhibitors were added 30 min before OXA treatment and then in combination with OXA for 24 h. In SH-SY5Y cells, OXA caused a significant dose-dependent decrease in viability, a large increase in ROS and NO production, lipid peroxidation and mitochondrial impairment as assessed by a drop in mitochondrial membrane potential, which are deleterious for the cell. An increase in levels of negatively charged phospholipids such as cardiolipin but also phosphatidylserine and phosphatidylinositol, was also observed. Additionally, OXA caused concentration-dependent P2X7 receptor activation, increased chromatin condensation and caspase-3 activation associated with TNF-α and IL-6 release. The majority of these toxic effects were equally observed in Raw 264.7 which also presented high levels of PGE2. Pretreatment of SH-SY5Y cells with pharmacological inhibitors significantly reduced or blocked all the neurotoxic OXA effects. In OXA-treated mice (28 mg/kg cumulated dose significant cold hyperalgesia and oxidative stress in the tested brain areas were shown. Our study suggests that targeting P2X7 receptor activation and mitochondrial impairment might be a potential therapeutic strategy against OXA-induced neuropathic pain.

  18. Inherent dynamics of head domain correlates with ATP-recognition of P2X4 receptors: insights gained from molecular simulations.

    Directory of Open Access Journals (Sweden)

    Li-Dong Huang

    Full Text Available P2X receptors are ATP-gated ion channels involved in many physiological functions, and determination of ATP-recognition (AR of P2X receptors will promote the development of new therapeutic agents for pain, inflammation, bladder dysfunction and osteoporosis. Recent crystal structures of the zebrafish P2X4 (zfP2X4 receptor reveal a large ATP-binding pocket (ABP located at the subunit interface of zfP2X4 receptors, which is occupied by a conspicuous cluster of basic residues to recognize triphosphate moiety of ATP. Using the engineered affinity labeling and molecular modeling, at least three sites (S1, S2 and S3 within ABP have been identified that are able to recognize the adenine ring of ATP, implying the existence of at least three distinct AR modes in ABP. The open crystal structure of zfP2X4 confirms one of three AR modes (named AR1, in which the adenine ring of ATP is buried into site S1 while the triphosphate moiety interacts with clustered basic residues. Why architecture of ABP favors AR1 not the other two AR modes still remains unexplored. Here, we examine the potential role of inherent dynamics of head domain, a domain involved in ABP formation, in AR determinant of P2X4 receptors. In silico docking and binding free energy calculation revealed comparable characters of three distinct AR modes. Inherent dynamics of head domain, especially the downward motion favors the preference of ABP for AR1 rather than AR2 and AR3. Along with the downward motion of head domain, the closing movement of loop139-146 and loop169-183, and structural rearrangements of K70, K72, R298 and R143 enabled ABP to discriminate AR1 from other AR modes. Our observations suggest the essential role of head domain dynamics in determining AR of P2X4 receptors, allowing evaluation of new strategies aimed at developing specific blockers/allosteric modulators by preventing the dynamics of head domain associated with both AR and channel activation of P2X4 receptors.

  19. P2X7-Regulated Protection from Exacerbations and Loss of Control Is Independent of Asthma Maintenance Therapy

    Science.gov (United States)

    Manthei, David M.; Seibold, Max A.; Ahn, Kwangmi; Bleecker, Eugene; Boushey, Homer A.; Calhoun, William J.; Castro, Mario; Chinchili, Vernon M.; Fahy, John V.; Hawkins, Greg A.; Icitovic, Nicolina; Israel, Elliot; Jarjour, Nizar N.; King, Tonya; Kraft, Monica; Lazarus, Stephen C.; Lehman, Erik; Martin, Richard J.; Meyers, Deborah A.; Peters, Stephen P.; Sheerar, Dagna; Shi, Lei; Sutherland, E. Rand; Szefler, Stanley J.; Wechsler, Michael E.; Sorkness, Christine A.; Lemanske, Robert F.

    2013-01-01

    Rationale: The function of the P2X7 nucleotide receptor protects against exacerbation in people with mild-intermittent asthma during viral illnesses, but the impact of disease severity and maintenance therapy has not been studied. Objectives: To evaluate the association between P2X7, asthma exacerbations, and incomplete symptom control in a more diverse population. Methods: A matched P2RX7 genetic case-control was performed with samples from Asthma Clinical Research Network trial participants enrolled before July 2006, and P2X7 pore activity was determined in whole blood samples as an ancillary study to two trials completed subsequently. Measurements and Main Results: A total of 187 exacerbations were studied in 742 subjects, and the change in asthma symptom burden was studied in an additional 110 subjects during a trial of inhaled corticosteroids (ICS) dose optimization. African American carriers of the minor G allele of the rs2230911 loss-of-function single nucleotide polymorphism were more likely to have a history of prednisone use in the previous 12 months, with adjustment for ICS and long-acting β2-agonists use (odds ratio, 2.7; 95% confidence interval, 1.2–6.2; P = 0.018). Despite medium-dose ICS, attenuated pore function predicted earlier exacerbations in incompletely controlled patients with moderate asthma (hazard ratio, 3.2; confidence interval, 1.1–9.3; P = 0.033). After establishing control with low-dose ICS in patients with mild asthma, those with attenuated pore function had more asthma symptoms, rescue albuterol use, and FEV1 reversal (P < 0.001, 0.03, and 0.03, respectively) during the ICS adjustment phase. Conclusions: P2X7 pore function protects against exacerbations of asthma and loss of control, independent of baseline severity and the maintenance therapy. PMID:23144325

  20. Presynaptic inhibition of spontaneous acetylcholine release mediated by P2Y receptors at the mouse neuromuscular junction.

    Science.gov (United States)

    De Lorenzo, S; Veggetti, M; Muchnik, S; Losavio, A

    2006-09-29

    At the neuromuscular junction, ATP is co-released with the neurotransmitter acetylcholine (ACh) and once in the synaptic space, it is degraded to the presynaptically active metabolite adenosine. Intracellular recordings were performed on diaphragm fibers of CF1 mice to determine the action of extracellular ATP (100 muM) and the slowly hydrolysable ATP analog 5'-adenylylimidodiphosphate lithium (betagamma-imido ATP) (30 muM) on miniature end-plate potential (MEPP) frequency. We found that application of ATP and betagamma-imido ATP decreased spontaneous secretion by 45.3% and 55.9% respectively. 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX), a selective A(1) adenosine receptor antagonist and alpha,beta-methylene ADP sodium salt (alphabeta-MeADP), which is an inhibitor of ecto-5'-nucleotidase, did not prevent the inhibitory effect of ATP, demonstrating that the nucleotide is able to modulate spontaneous ACh release through a mechanism independent of the action of adenosine. Blockade of Ca(2+) channels by both, Cd(2+) or the combined application of nitrendipine and omega-conotoxin GVIA (omega-CgTx) (L-type and N-type Ca(2+) channel antagonists, respectively) prevented the effect of betagamma-imido ATP, indicating that the nucleotide modulates Ca(2+) influx through the voltage-dependent Ca(2+) channels related to spontaneous secretion. betagamma-Imido ATP-induced modulation was antagonized by the non-specific P2 receptor antagonist suramin and the P2Y receptor antagonist 1-amino-4-[[4-[[4-chloro-6-[[3(or4)-sulfophenyl] amino]-1,3,5-triazin-2-yl]amino]-3-sulfophenyl] amino]-9,10-dihydro-9,10-dioxo-2-anthracenesulfonic acid (reactive blue-2), but not by pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid) tetrasodium salt (PPADS), which has a preferential antagonist effect on P2X receptors. Pertussis toxin and N-ethylmaleimide (NEM), which are blockers of G(i/o) proteins, prevented the action of the nucleotide, suggesting that the effect is mediated by P2Y receptors

  1. Multifunctional pH-Responsive Folate Receptor Mediated Polymer Nanoparticles for Drug Delivery.

    Science.gov (United States)

    Cai, Xiaoqing; Yang, Xiaoye; Wang, Fang; Zhang, Chen; Sun, Deqing; Zhai, Guangxi

    2016-07-01

    Multifunctional pH-responsive folate receptor mediated targeted polymer nanoparticles (TPNps) were developed for docetaxel (DTX) delivery based on poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)poly (β-amino ester) (P123-PAE) and poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)-folate (P123-FA) copolymers. The DTX was loaded into the TPNps with a decent drug loading content of 15.02 ± 0.14 wt%. In vitro drug release results showed that the DTX was released from the TPNps at a pH-dependent manner. Tetrazolium dye (MTT) assay revealed that the bland polymer nanoparticles displayed almost nontoxicity at 200 μg/mL concentration. However, the DTX-loaded TPNps showed high anti-tumor activity at low IC50 (0.72 μg/mL) for MCF-7 cells following 48 h incubation. Cellular uptake experiments revealed that the TPNps had higher degree of cellular uptake than nontargeted polymer nanoparticles, indicating that the nanoparticles were internalized into the cells via FA receptor-mediated endocytosis. Moreover, the cellular uptake pathways for the FA grafted polymer were involved in energy-dependent, clathrin-mediated and caveolae-mediated endocytosis. The cell killing effect and cellular uptake of the DTX-TPNps by the MCF-7 cells were all enhanced by about two folds at pH 5.5 when compared with pH 7.4. The TPNps also significantly prolonged the in vivo retention time for the DTX. These results suggest that the biocompatible pH responsive folate-modified polymer nanoparticles present a promising safe nanosystem for intracellular targeted delivery of DTX.

  2. Nicotine impairs cyclooxygenase-2-dependent kinin-receptor-mediated murine airway relaxations

    International Nuclear Information System (INIS)

    Xu, Yuan; Cardell, Lars-Olaf

    2014-01-01

    Introduction: Cigarette smoke induces local inflammation and airway hyperreactivity. In asthmatics, it worsens the symptoms and increases the risk for exacerbation. The present study investigates the effects of nicotine on airway relaxations in isolated murine tracheal segments. Methods: Segments were cultured for 24 h in the presence of vehicle, nicotine (10 μM) and/or dexamethasone (1 μM). Airway relaxations were assessed in myographs after pre-contraction with carbachol (1 μM). Kinin receptors, cyclooxygenase (COX) and inflammatory mediator expressions were assessed by real-time PCR and confocal-microscopy-based immunohistochemistry. Results: The organ culture procedure markedly increased bradykinin- (selective B 2 receptor agonist) and des-Arg 9 -bradykinin- (selective B 1 receptor agonist) induced relaxations, and slightly increased relaxation induced by isoprenaline, but not that induced by PGE 2 . The kinin receptor mediated relaxations were epithelium-, COX-2- and EP2-receptor-dependent and accompanied by drastically enhanced mRNA levels of kinin receptors, as well as inflammatory mediators MCP-1 and iNOS. Increase in COX-2 and mPGES-1 was verified both at mRNA and protein levels. Nicotine selectively suppressed the organ-culture-enhanced relaxations induced by des-Arg 9 -bradykinin and bradykinin, at the same time reducing mPGES-1 mRNA and protein expressions. α7-nicotinic acetylcholine receptor inhibitors α-bungarotoxin and MG624 both blocked the nicotine effects on kinin B 2 receptors, but not those on B 1 . Dexamethasone completely abolished kinin-induced relaxations. Conclusion: It is tempting to conclude that a local inflammatory process per se could have a bronchoprotective component by increasing COX-2 mediated airway relaxations and that nicotine could impede this safety mechanism. Dexamethasone further reduced airway inflammation together with relaxations. This might contribute to the steroid resistance seen in some patients with asthma

  3. Nicotine impairs cyclooxygenase-2-dependent kinin-receptor-mediated murine airway relaxations

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yuan, E-mail: yuan.xu@ki.se; Cardell, Lars-Olaf

    2014-02-15

    Introduction: Cigarette smoke induces local inflammation and airway hyperreactivity. In asthmatics, it worsens the symptoms and increases the risk for exacerbation. The present study investigates the effects of nicotine on airway relaxations in isolated murine tracheal segments. Methods: Segments were cultured for 24 h in the presence of vehicle, nicotine (10 μM) and/or dexamethasone (1 μM). Airway relaxations were assessed in myographs after pre-contraction with carbachol (1 μM). Kinin receptors, cyclooxygenase (COX) and inflammatory mediator expressions were assessed by real-time PCR and confocal-microscopy-based immunohistochemistry. Results: The organ culture procedure markedly increased bradykinin- (selective B{sub 2} receptor agonist) and des-Arg{sup 9}-bradykinin- (selective B{sub 1} receptor agonist) induced relaxations, and slightly increased relaxation induced by isoprenaline, but not that induced by PGE{sub 2}. The kinin receptor mediated relaxations were epithelium-, COX-2- and EP2-receptor-dependent and accompanied by drastically enhanced mRNA levels of kinin receptors, as well as inflammatory mediators MCP-1 and iNOS. Increase in COX-2 and mPGES-1 was verified both at mRNA and protein levels. Nicotine selectively suppressed the organ-culture-enhanced relaxations induced by des-Arg{sup 9}-bradykinin and bradykinin, at the same time reducing mPGES-1 mRNA and protein expressions. α7-nicotinic acetylcholine receptor inhibitors α-bungarotoxin and MG624 both blocked the nicotine effects on kinin B{sub 2} receptors, but not those on B{sub 1}. Dexamethasone completely abolished kinin-induced relaxations. Conclusion: It is tempting to conclude that a local inflammatory process per se could have a bronchoprotective component by increasing COX-2 mediated airway relaxations and that nicotine could impede this safety mechanism. Dexamethasone further reduced airway inflammation together with relaxations. This might contribute to the steroid resistance seen in

  4. [The Relationship Study between Expressions of P2X5 Receptor and Deficiency-cold Syndrome/Deficiency-heat Syndrome at Various Ambient Temperatures].

    Science.gov (United States)

    Yang, Li-ping; Yu, Hong-jie; Huang, Rui; Li, Xin-min; Zhan, Xiang-hong; Hou, Jun-lin

    2015-05-01

    To detect the expression of the peripheral blood P2X5 receptor at various ambient temperatures, and to explore its relationship with deficiency-cold syndrome and deficiency-heat syndrome. Subjects were selected by questionnaire and expert diagnosis, and assigned to the normal control group, the deficiency-cold syndrome group, and the deficiency-heat syndrome group, 20 in each group. 5 mL venous blood was collected at room temperature (25 °C) and cold temperature (-4-5 °C) respectively. Then the expression of P2X5 receptor was relatively quantified by real-time fluorescence quantitative PCR, and compared at room temperature and cold temperature respectively. The expression of P2X5 receptor in deficiency-cold syndrome and deficiency-heat syndrome groups was lower than that in the normal control group at room temperature (P cold temperature in the deficiency-cold syndrome group than in the normal control group (P receptor showed no difference in all groups at two different temperatures (P > 0.05). The expression of P2X5 receptor was different in different syndrome groups at various ambient temperatures. Ambient temperatures had insignificant effect on the expression of P2X5 receptor of the population with the same syndrome.

  5. Impaired P2X signalling pathways in renal microvascular myocytes in genetic hypertension

    KAUST Repository

    Gordienko, Dmitri V.; Povstyan, Oleksandr V.; Sukhanova, Khrystyna Yu; Raphaë l, Maylis; Harhun, Maksym I.; Dyskina, Yulia; Lehen'Kyi, V'Yacheslav; Jama, Abdirahman Mahmoud; Lu, Zhiliang; Skryma, Roman N.; Prevarskaya, Natalia B.

    2014-01-01

    Aims P2X receptors (P2XRs) mediate sympathetic control and autoregulation of renal circulation triggering preglomerular vasoconstriction, which protects glomeruli from elevated pressures. Although previous studies established a casual link between glomerular susceptibility to hypertensive injury and decreased preglomerular vascular reactivity to P2XR activation, the mechanisms of attenuation of the P2XR signalling in hypertension remained unknown. We aimed to analyse molecular mechanisms of the impairment of P2XR signalling in renal vascular smooth muscle cells (RVSMCs) in genetic hypertension. Methods and results We compared the expression of pertinent genes and P2XR-linked Ca2+ entry and Ca2+ release mechanisms in RVSMCs of spontaneously hypertensive rats (SHRs) and their normotensive controls, Wistar Kyoto (WKY) rats. We found that, in SHR RVSMCs, P2XR-linked Ca2+ entry and Ca2+ release from the sarcoplasmic reticulum (SR) are both significantly reduced. The former is due to down-regulation of the P2X1 subunit. The latter is caused by a decrease of the SR Ca2+ load. The SR Ca2+ load reduction is caused by attenuated Ca2+ uptake via down-regulated sarco-/endoplasmic reticulum Ca2+-ATPase 2b and elevated Ca2+ leak from the SR via ryanodine receptors (RyRs) and inositol 1,4,5-trisphosphate receptors. Spontaneous activity of these Ca2+-release channels is augmented due to up-regulation of RyR type 2 and elevated IP3 production by up-regulated phospholipase C-β1. Conclusions Our study unravels the cellular and molecular mechanisms of attenuation of P2XR-mediated preglomerular vasoconstriction that elevates glomerular susceptibility to harmful hypertensive pressures. This provides an important impetus towards understanding of the pathology of hypertensive renal injury.

  6. Impaired P2X signalling pathways in renal microvascular myocytes in genetic hypertension

    KAUST Repository

    Gordienko, Dmitri V.

    2014-12-16

    Aims P2X receptors (P2XRs) mediate sympathetic control and autoregulation of renal circulation triggering preglomerular vasoconstriction, which protects glomeruli from elevated pressures. Although previous studies established a casual link between glomerular susceptibility to hypertensive injury and decreased preglomerular vascular reactivity to P2XR activation, the mechanisms of attenuation of the P2XR signalling in hypertension remained unknown. We aimed to analyse molecular mechanisms of the impairment of P2XR signalling in renal vascular smooth muscle cells (RVSMCs) in genetic hypertension. Methods and results We compared the expression of pertinent genes and P2XR-linked Ca2+ entry and Ca2+ release mechanisms in RVSMCs of spontaneously hypertensive rats (SHRs) and their normotensive controls, Wistar Kyoto (WKY) rats. We found that, in SHR RVSMCs, P2XR-linked Ca2+ entry and Ca2+ release from the sarcoplasmic reticulum (SR) are both significantly reduced. The former is due to down-regulation of the P2X1 subunit. The latter is caused by a decrease of the SR Ca2+ load. The SR Ca2+ load reduction is caused by attenuated Ca2+ uptake via down-regulated sarco-/endoplasmic reticulum Ca2+-ATPase 2b and elevated Ca2+ leak from the SR via ryanodine receptors (RyRs) and inositol 1,4,5-trisphosphate receptors. Spontaneous activity of these Ca2+-release channels is augmented due to up-regulation of RyR type 2 and elevated IP3 production by up-regulated phospholipase C-β1. Conclusions Our study unravels the cellular and molecular mechanisms of attenuation of P2XR-mediated preglomerular vasoconstriction that elevates glomerular susceptibility to harmful hypertensive pressures. This provides an important impetus towards understanding of the pathology of hypertensive renal injury.

  7. Immunocytochemical analysis of P2X2 in rat circumvallate taste buds.

    Science.gov (United States)

    Yang, Ruibiao; Montoya, Alana; Bond, Amanda; Walton, Jenna; Kinnamon, John C

    2012-05-23

    Our laboratory has shown that classical synapses and synaptic proteins are associated with Type III cells. Yet it is generally accepted that Type II cells transduce bitter, sweet and umami stimuli. No classical synapses, however, have been found associated with Type II cells. Recent studies indicate that the ionotropic purinergic receptors P2X2/P2X3 are present in rodent taste buds. Taste nerve processes express the ionotropic purinergic receptors (P2X2/P2X3). P2X2/P2X3(Dbl-/-) mice are not responsive to sweet, umami and bitter stimuli, and it has been proposed that ATP acts as a neurotransmitter in taste buds. The goal of the present study is to learn more about the nature of purinergic contacts in rat circumvallate taste buds by examining immunoreactivity to antisera directed against the purinergic receptor P2X2. P2X2-like immunoreactivity is present in intragemmal nerve processes in rat circumvallate taste buds. Intense immunoreactivity can also be seen in the subgemmal nerve plexuses located below the basal lamina. The P2X2 immunoreactive nerve processes also display syntaxin-1-LIR. The immunoreactive nerves are in close contact with the IP(3)R3-LIR Type II cells and syntaxin-1-LIR and/or 5-HT-LIR Type III cells. Taste cell synapses are observed only from Type III taste cells onto P2X2-LIR nerve processes. Unusually large, "atypical" mitochondria in the Type II taste cells are found only at close appositions with P2X2-LIR nerve processes. P2X2 immunogold particles are concentrated at the membranes of nerve processes at close appositions with taste cells. Based on our immunofluorescence and immunoelectron microscopical studies we believe that both perigemmal and most all intragemmal nerve processes display P2X2-LIR. Moreover, colloidal gold immunoelectron microscopy indicates that P2X2-LIR in nerve processes is concentrated at sites of close apposition with Type II cells. This supports the hypothesis that ATP may be a key neurotransmitter in taste transduction

  8. Ihh enhances differentiation of CFK-2 chondrocytic cells and antagonizes PTHrP-mediated activation of PKA.

    Science.gov (United States)

    Deckelbaum, Ron A; Chan, George; Miao, Dengshun; Goltzman, David; Karaplis, Andrew C

    2002-07-15

    Indian Hedgehog (Ihh), a member of the hedgehog (HH) family of secreted morphogens, and parathyroid hormone-related peptide (PTHrP) are key regulators of cartilage cell (chondrocyte) differentiation. We have investigated, in vitro, the actions of HH signalling and its possible interplay with PTHrP using rat CFK-2 chondrocytic cells. Markers of chondrocyte differentiation [alkaline phosphatase (ALP) activity, and type II (Col2a1) and type X collagen (Col10a1) expression] were enhanced by overexpression of Ihh or its N-terminal domain (N-Ihh), effects mimicked by exogenous administration of recombinant N-terminal HH peptide. Moreover, a missense mutation mapping to the N-terminal domain of Ihh (W160G) reduces the capacity of N-Ihh to induce differentiation. Prolonged exposure of CFK-2 cells to exogenous N-Shh (5x10(-9) M) in the presence of PTHrP (10(-8) M) or forskolin (10(-7) M) resulted in perturbation of HH-mediated differentiation. In addition, overexpression of a constitutively active form of the PTHrP receptor (PTHR1 H223R) inhibited Ihh-mediated differentiation, implicating activation of protein kinase A (PKA) by PTHR1 as a probable mediator of the antagonistic effects of PTHrP. Conversely, overexpression of Ihh/N-Ihh or exogenous treatment with N-Shh led to dampening of PTHrP-mediated activation of PKA. Taken together, our data suggest that Ihh harbors the capacity to induce rather than inhibit chondrogenic differentiation, that PTHrP antagonizes HH-mediated differentiation through a PKA-dependent mechanism and that HH signalling, in turn, modulates PTHrP action through functional inhibition of signalling by PTHR1 to PKA.

  9. Regulation of human cerebro-microvascular endothelial baso-lateral adhesion and barrier function by S1P through dual involvement of S1P1 and S1P2 receptors.

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    Wiltshire, Rachael; Nelson, Vicky; Kho, Dan Ting; Angel, Catherine E; O'Carroll, Simon J; Graham, E Scott

    2016-01-27

    Herein we show that S1P rapidly and acutely reduces the focal adhesion strength and barrier tightness of brain endothelial cells. xCELLigence biosensor technology was used to measure focal adhesion, which was reduced by S1P acutely and this response was mediated through both S1P1 and S1P2 receptors. S1P increased secretion of several pro-inflammatory mediators from brain endothelial cells. However, the magnitude of this response was small in comparison to that mediated by TNFα or IL-1β. Furthermore, S1P did not significantly increase cell-surface expression of any key cell adhesion molecules involved in leukocyte recruitment, included ICAM-1 and VCAM-1. Finally, we reveal that S1P acutely and dynamically regulates microvascular endothelial barrier tightness in a manner consistent with regulated rapid opening followed by closing and strengthening of the barrier. We hypothesise that the role of the S1P receptors in this process is not to cause barrier dysfunction, but is related to controlled opening of the endothelial junctions. This was revealed using real-time measurement of barrier integrity using ECIS ZΘ TEER technology and endothelial viability using xCELLigence technology. Finally, we show that these responses do not occur simply though the pharmacology of a single S1P receptor but involves coordinated action of S1P1 and S1P2 receptors.

  10. Heavy metals modulate the activity of the purinergic P2X4 receptor

    International Nuclear Information System (INIS)

    Coddou, Claudio; Lorca, Ramon A.; Acuna-Castillo, Claudio; Grauso, Marta; Rassendren, Francois; Huidobro-Toro, J.Pablo

    2005-01-01

    To further characterize the nature of the regulatory metal-binding sites of the rat P2X 4 receptor, several transition heavy metals were tested to examine their ability to mimic the facilitator action of zinc or the inhibitory action of copper. cDNA coding for the rat P2X 4 receptor was injected into Xenopus laevis oocytes; the two-electrode voltage-clamp technique was used to measure and quantify the ATP-evoked currents in the absence or presence of the metals. Cadmium facilitated the ATP-gated currents in a reversible and voltage-independent manner; maximal potentiation occurred within less than 1 min. Cadmium displaced leftward, in a concentration-dependent manner, the ATP concentration-response curve. In contrast, mercury reduced the ATP-gated currents in a reversible, time, and concentration manner. Maximal inhibition occurred after about 5 min of metal application. Cobalt also augmented the ATP-evoked currents, but its action was long lasting and did not reverse even after 45 min of metal washout. Other metals such as lead, nickel, manganese, silver, or gallium did not significantly alter the ATP-gated currents. The co-application of cadmium plus zinc or mercury plus copper caused additive effects. Mutation of H140 by alanine (H140A) augmented both the cadmium-induced facilitation and the mercury-induced inhibition. In contrast, the H241A mutant showed characteristics indistinguishable from the wild type. The H286A mutant showed a normal cadmium-induced potentiation, but an increased mercury inhibition. Out of the metals examined, only cadmium mimicked closely the action of zinc, evidencing commonalities. While mercury mimicked the action of copper, both metals apparently interact at distinct metal-binding sites. The present findings allow us to infer that heavy metals modulate the P2X 4 receptor by acting in at least three separate metal-binding sites

  11. Effect of static magnetic field on pain level and expression of P2X3 receptors in the trigeminal ganglion in mice following experimental tooth movement.

    Science.gov (United States)

    Zhu, Yafen; Wang, Shengguo; Long, Hu; Zhu, Jingyi; Jian, Fan; Ye, Niansong; Lai, Wenli

    2017-01-01

    Recent research has demonstrated that static magnetic fields (SMF) can generate an analgesic effect in different conditions. The present study explored effects of SMF on pain levels and expressions of P2X3 receptors in trigeminal ganglion (TG) in mice after experimental tooth movement (tooth movement induced by springs between teeth). Experiments were performed in male mice (body mass: 25-30 g) and divided into SMF + force group, force group, and no force group. Exposure time was over 22 h per day. Mouse Grimace Scale was used for evaluating orofacial pain levels during experimental tooth movement at 4 h and 1, 3, 7, and 14 days. Meanwhile, expression levels of P2X3 receptors in the TG were evaluated by immunohistochemistry and western blotting at same time points. We finally found that during experimental tooth movement, pain levels of mice peaked at 3 days, and then decreased. While pain levels of mice were reduced in the SMF environment at 4 h, 1 and 3 days, there was a significant difference at 1 and 3 days. Meanwhile, under the action of SMF, expression levels of P2X3 receptors in TG were significantly lower at 4 h, 3 and 7 days. These results suggest that SMF can reduce pain levels in mice, and down-regulate P2X3 receptors in TG. Bioelectromagnetics. 38:22-30, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  12. Immunocytochemical analysis of P2X2 in rat circumvallate taste buds

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    Yang Ruibiao

    2012-05-01

    Full Text Available Abstract Background Our laboratory has shown that classical synapses and synaptic proteins are associated with Type III cells. Yet it is generally accepted that Type II cells transduce bitter, sweet and umami stimuli. No classical synapses, however, have been found associated with Type II cells. Recent studies indicate that the ionotropic purinergic receptors P2X2/P2X3 are present in rodent taste buds. Taste nerve processes express the ionotropic purinergic receptors (P2X2/P2X3. P2X2/P2X3Dbl−/− mice are not responsive to sweet, umami and bitter stimuli, and it has been proposed that ATP acts as a neurotransmitter in taste buds. The goal of the present study is to learn more about the nature of purinergic contacts in rat circumvallate taste buds by examining immunoreactivity to antisera directed against the purinergic receptor P2X2. Results P2X2-like immunoreactivity is present in intragemmal nerve processes in rat circumvallate taste buds. Intense immunoreactivity can also be seen in the subgemmal nerve plexuses located below the basal lamina. The P2X2 immunoreactive nerve processes also display syntaxin-1-LIR. The immunoreactive nerves are in close contact with the IP3R3-LIR Type II cells and syntaxin-1-LIR and/or 5-HT-LIR Type III cells. Taste cell synapses are observed only from Type III taste cells onto P2X2-LIR nerve processes. Unusually large, “atypical” mitochondria in the Type II taste cells are found only at close appositions with P2X2-LIR nerve processes. P2X2 immunogold particles are concentrated at the membranes of nerve processes at close appositions with taste cells. Conclusions Based on our immunofluorescence and immunoelectron microscopical studies we believe that both perigemmal and most all intragemmal nerve processes display P2X2-LIR. Moreover, colloidal gold immunoelectron microscopy indicates that P2X2-LIR in nerve processes is concentrated at sites of close apposition with Type II cells. This supports the hypothesis

  13. P2Y6 Receptor Activation Promotes Inflammation and Tissue Remodeling in Pulmonary Fibrosis

    Science.gov (United States)

    Müller, Tobias; Fay, Susanne; Vieira, Rodolfo Paula; Karmouty-Quintana, Harry; Cicko, Sanja; Ayata, Cemil Korcan; Zissel, Gernot; Goldmann, Torsten; Lungarella, Giuseppe; Ferrari, Davide; Di Virgilio, Francesco; Robaye, Bernard; Boeynaems, Jean-Marie; Lazarowski, Eduardo R.; Blackburn, Michael R.; Idzko, Marco

    2017-01-01

    Idiopathic pulmonary fibrosis (IPF) is a disease with a poor prognosis and very few available treatment options. The involvement of the purinergic receptor subtypes P2Y2 and P2X7 in fibrotic lung disease has been demonstrated recently. In this study, we investigated the role of P2Y6 receptors in the pathogenesis of IPF in humans and in the animal model of bleomycin-induced lung injury. P2Y6R expression was upregulated in lung structural cells but not in bronchoalveolar lavage (BAL) cells derived from IPF patients as well as in animals following bleomycin administration. Furthermore, BAL fluid levels of the P2Y6R agonist uridine-5′-diphosphate were elevated in animals with bleomycin-induced pulmonary fibrosis. Inflammation and fibrosis following bleomycin administration were reduced in P2Y6R-deficient compared to wild-type animals confirming the pathophysiological relevance of P2Y6R subtypes for fibrotic lung diseases. Experiments with bone marrow chimeras revealed the importance of P2Y6R expression on lung structural cells for pulmonary inflammation and fibrosis. Similar effects were obtained when animals were treated with the P2Y6R antagonist MRS2578. In vitro studies demonstrated that proliferation and secretion of the pro-inflammatory/pro-fibrotic cytokine IL-6 by lung fibroblasts are P2Y6R-mediated processes. In summary, our results clearly demonstrate the involvement of P2Y6R subtypes in the pathogenesis of pulmonary fibrosis. Thus, blocking pulmonary P2Y6 receptors might be a new target for the treatment of IPF. PMID:28878780

  14. P2Y6 Receptor Activation Promotes Inflammation and Tissue Remodeling in Pulmonary Fibrosis

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    Tobias Müller

    2017-08-01

    Full Text Available Idiopathic pulmonary fibrosis (IPF is a disease with a poor prognosis and very few available treatment options. The involvement of the purinergic receptor subtypes P2Y2 and P2X7 in fibrotic lung disease has been demonstrated recently. In this study, we investigated the role of P2Y6 receptors in the pathogenesis of IPF in humans and in the animal model of bleomycin-induced lung injury. P2Y6R expression was upregulated in lung structural cells but not in bronchoalveolar lavage (BAL cells derived from IPF patients as well as in animals following bleomycin administration. Furthermore, BAL fluid levels of the P2Y6R agonist uridine-5′-diphosphate were elevated in animals with bleomycin-induced pulmonary fibrosis. Inflammation and fibrosis following bleomycin administration were reduced in P2Y6R-deficient compared to wild-type animals confirming the pathophysiological relevance of P2Y6R subtypes for fibrotic lung diseases. Experiments with bone marrow chimeras revealed the importance of P2Y6R expression on lung structural cells for pulmonary inflammation and fibrosis. Similar effects were obtained when animals were treated with the P2Y6R antagonist MRS2578. In vitro studies demonstrated that proliferation and secretion of the pro-inflammatory/pro-fibrotic cytokine IL-6 by lung fibroblasts are P2Y6R-mediated processes. In summary, our results clearly demonstrate the involvement of P2Y6R subtypes in the pathogenesis of pulmonary fibrosis. Thus, blocking pulmonary P2Y6 receptors might be a new target for the treatment of IPF.

  15. Covalent modification of mutant rat P2X2 receptors with a thiol-reactive fluorophore allows channel activation by zinc or acidic pH without ATP.

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    Shlomo S Dellal

    Full Text Available Rat P2X2 receptors open at an undetectably low rate in the absence of ATP. Furthermore, two allosteric modulators, zinc and acidic pH, cannot by themselves open these channels. We describe here the properties of a mutant receptor, K69C, before and after treatment with the thiol-reactive fluorophore Alexa Fluor 546 C(5-maleimide (AM546. Xenopus oocytes expressing unmodified K69C were not activated under basal conditions nor by 1,000 µM ATP. AM546 treatment caused a small increase in the inward holding current which persisted on washout and control experiments demonstrated this current was due to ATP independent opening of the channels. Following AM546 treatment, zinc (100 µM or acidic external solution (pH 6.5 elicited inward currents when applied without any exogenous ATP. In the double mutant K69C/H319K, zinc elicited much larger inward currents, while acidic pH generated outward currents. Suramin, which is an antagonist of wild type receptors, behaved as an agonist at AM546-treated K69C receptors. Several other cysteine-reactive fluorophores tested on K69C did not cause these changes. These modified receptors show promise as a tool for studying the mechanisms of P2X receptor activation.

  16. Characterization of muscarinic and P2X receptors in the urothelium and detrusor muscle of the rat bladder

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    Masaki Ogoda

    2016-05-01

    Full Text Available Muscarinic and purinergic (P2X receptors play critical roles in bladder urothelium under physiological and pathological conditions. Aim of present study was to characterize these receptors in rat bladder urothelium and detrusor muscle using selective radioligands of [N-methyl-3H]scopolamine methyl chloride ([3H]NMS and αβ-methylene ATP [2,8-3H]tetrasodium salt ([3H]αβ-MeATP. Similar binding parameters for each radioligand were observed in urothelium and detrusor muscle. Pretreatment with N-(2-chloroethyl-4-piperidinyl diphenylacetate (4-DAMP mustard mustard revealed co-existence of M2 and M3 receptors, with the number of M2 receptors being larger in the urothelium and detrusor muscle. Intravesical administration of imidafenacin and Dpr-P-4 (N → O (active metabolite of propiverine displayed significant binding of muscarinic receptors in the urothelium and detrusor muscle. The treatment with cyclophosphamide (CYP or resiniferatoxin (RTX resulted in a significant decrease in maximal number of binding sites (Bmax for [3H]NMS and/or [3H]αβ-MeATP in the urothelium and detrusor muscle. These results demonstrated that 1 pharmacological characteristics of muscarinic and P2X receptors in rat bladder urothelium were similar to those in the detrusor muscle, 2 that densities of these receptors were significantly altered by pretreatments with CYP and RTX, and 3 that these receptors may be pharmacologically affected by imidafenacin and Dpr-P-4 (N → O which are excreted in the urine.

  17. Multiple roles of the extracellular vestibule amino acid residues in the function of the rat P2X4 receptor.

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    Milos B Rokic

    Full Text Available The binding of ATP to trimeric P2X receptors (P2XR causes an enlargement of the receptor extracellular vestibule, leading to opening of the cation-selective transmembrane pore, but specific roles of vestibule amino acid residues in receptor activation have not been evaluated systematically. In this study, alanine or cysteine scanning mutagenesis of V47-V61 and F324-N338 sequences of rat P2X4R revealed that V49, Y54, Q55, F324, and G325 mutants were poorly responsive to ATP and trafficking was only affected by the V49 mutation. The Y54F and Y54W mutations, but not the Y54L mutation, rescued receptor function, suggesting that an aromatic residue is important at this position. Furthermore, the Y54A and Y54C receptor function was partially rescued by ivermectin, a positive allosteric modulator of P2X4R, suggesting a rightward shift in the potency of ATP to activate P2X4R. The Q55T, Q55N, Q55E, and Q55K mutations resulted in non-responsive receptors and only the Q55E mutant was ivermectin-sensitive. The F324L, F324Y, and F324W mutations also rescued receptor function partially or completely, ivermectin action on channel gating was preserved in all mutants, and changes in ATP responsiveness correlated with the hydrophobicity and side chain volume of the substituent. The G325P mutant had a normal response to ATP, suggesting that G325 is a flexible hinge. A topological analysis revealed that the G325 and F324 residues disrupt a β-sheet upon ATP binding. These results indicate multiple roles of the extracellular vestibule amino acid residues in the P2X4R function: the V49 residue is important for receptor trafficking to plasma membrane, the Y54 and Q55 residues play a critical role in channel gating and the F324 and G325 residues are critical for vestibule widening.

  18. The purinergic 2X7 receptor participates in renal inflammation and injury induced by high-fat diet: possible role of NLRP3 inflammasome activation.

    Science.gov (United States)

    Solini, Anna; Menini, Stefano; Rossi, Chiara; Ricci, Carlo; Santini, Eleonora; Blasetti Fantauzzi, Claudia; Iacobini, Carla; Pugliese, Giuseppe

    2013-11-01

    Renal disease associated with type 2 diabetes and the metabolic syndrome is characterized by a distinct inflammatory phenotype. The purinergic 2X7 receptor (P2X7 R) and the nucleotide-binding and oligomerization domain-like receptor containing a pyrin domain 3 (NLRP3) inflammasome have been separately shown to play a role in two models of non-metabolic chronic kidney disease. Moreover, the NLRP3 inflammasome has been implicated in chronic low-grade sterile inflammation characterizing metabolic disorders, though the mechanism(s) involved in inflammasome activation under these conditions are still unknown. We investigated the role of P2X7 R (through activation of the NLRP3 inflammasome) in renal inflammation and injury induced by a high-fat diet, an established model of the metabolic syndrome. On a high-fat diet, mice lacking P2X7 R developed attenuated renal functional and structural alterations as well as reduced inflammation, fibrosis, and oxidative/carbonyl stress, as compared with wild-type animals, in the absence of significant differences in metabolic parameters. This was associated with blunted up-regulation of the NLRP3 inflammasome components NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), pro-caspase 1, pro-interleukin (IL)-1β, and pro-IL-18, as well as reduced inflammasome activation, as evidenced by decreased formation of mature caspase 1, whereas mature IL-1β and IL-18 were not detected. Up-regulated expression of NLRP3 and pro-caspase 1, post-translational processing of pro-caspase-1, and release of IL-18 in response to lipopolysaccharide + 2'(3')-O-(4-benzoylbenzoyl)ATP were attenuated by P2X7 R silencing in cultured mouse podocytes. Protein and mRNA expression of P2X7 R, NLRP3, and ASC were also increased in kidneys from subjects with type 2 diabetes and the metabolic syndrome, showing histologically documented renal disease. These data provide evidence of a major role for the purinergic system, at

  19. Nucleotide transmitters ATP and ADP mediate intercellular calcium wave communication via P2Y12/13 receptors among BV-2 microglia.

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    Pengchong Jiang

    Full Text Available Nerve injury is accompanied by a liberation of diverse nucleotides, some of which act as 'find/eat-me' signals in mediating neuron-glial interplay. Intercellular Ca2+ wave (ICW communication is the main approach by which glial cells interact and coordinate with each other to execute immune defense. However, the detailed mechanisms on how these nucleotides participate in ICW communication remain largely unclear. In the present work, we employed a mechanical stimulus to an individual BV-2 microglia to simulate localized injury. Remarkable ICW propagation was observed no matter whether calcium was in the environment or not. Apyrase (ATP/ADP-hydrolyzing enzyme, suramin (broad-spectrum P2 receptor antagonist, 2-APB (IP3 receptor blocker and thapsigargin (endoplasmic reticulum calcium pump inhibitor potently inhibited these ICWs, respectively, indicating the dependence of nucleotide signals and P2Y receptors. Then, we detected the involvement of five naturally occurring nucleotides (ATP, ADP, UTP, UDP and UDP-glucose by desensitizing receptors. Results showed that desensitization with ATP and ADP could block ICW propagation in a dose-dependent manner, whereas other nucleotides had little effect. Meanwhile, the expression of P2Y receptors in BV-2 microglia was identified and their contributions were analyzed, from which we suggested P2Y12/13 receptors activation mostly contributed to ICWs. Besides, we estimated that extracellular ATP and ADP concentration sensed by BV-2 microglia was about 0.3 μM during ICWs by analyzing calcium dynamic characteristics. Taken together, these results demonstrated that the nucleotides ATP and ADP were predominant signal transmitters in mechanical stimulation-induced ICW communication through acting on P2Y12/13 receptors in BV-2 microglia.

  20. P2Y2 Receptor and EGFR Cooperate to Promote Prostate Cancer Cell Invasion via ERK1/2 Pathway.

    Science.gov (United States)

    Li, Wei-Hua; Qiu, Ying; Zhang, Hong-Quan; Tian, Xin-Xia; Fang, Wei-Gang

    2015-01-01

    As one member of G protein-coupled P2Y receptors, P2Y2 receptor can be equally activated by extracellular ATP and UTP. Our previous studies have proved that activation of P2Y2 receptor by extracellular ATP could promote prostate cancer cell invasion and metastasis in vitro and in vivo via regulating the expressions of some epithelial-mesenchymal transition/invasion-related genes (including IL-8, E-cadherin, Snail and Claudin-1), and the most significant change in expression of IL-8 was observed after P2Y2 receptor activation. However, the signaling pathway downstream of P2Y2 receptor and the role of IL-8 in P2Y2-mediated prostate cancer cell invasion remain unclear. Here, we found that extracellular ATP/UTP induced activation of EGFR and ERK1/2. After knockdown of P2Y2 receptor, the ATP -stimulated phosphorylation of EGFR and ERK1/2 was significantly suppressed. Further experiments showed that inactivation of EGFR and ERK1/2 attenuated ATP-induced invasion and migration, and suppressed ATP-mediated IL-8 production. In addition, knockdown of IL-8 inhibited ATP-mediated invasion and migration of prostate cancer cells. These findings suggest that P2Y2 receptor and EGFR cooperate to upregulate IL-8 production via ERK1/2 pathway, thereby promoting prostate cancer cell invasion and migration. Thus blocking of the P2Y2-EGFR-ERK1/2 pathway may provide effective therapeutic interventions for prostate cancer.

  1. Bradykinin Contributes to Sympathetic and Pressor Responses Evoked by Activation of Skeletal Muscle Afferents P2X in Heart Failure

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    Jihong Xing

    2016-11-01

    Full Text Available Background/Aims: Published data suggest that purinergic P2X receptors of muscle afferent nerves contribute to the enhanced sympathetic nervous activity (SNA and blood pressure (BP responses during static exercise in heart failure (HF. In this study, we examined engagement of bradykinin (BK in regulating responses of SNA and BP evoked by P2X stimulation in rats with HF. We further examined cellular mechanisms responsible for BK. We hypothesized that BK potentiates P2X currents of muscle dorsal root ganglion (DRG neurons, and this effect is greater in HF due to upregulation of BK kinin B2 and P2X3 receptor. As a result, BK amplifies muscle afferents P2X-mediated SNA and BP responses. Methods: Renal SNA and BP responses were recorded in control rats and rats with HF. Western Blot analysis and patch-clamp methods were employed to examine the receptor expression and function of DRG neurons involved in the effects of BK. Results: BK injected into the arterial blood supply of the hindlimb muscles heightened the reflex SNA and BP responses induced by P2X activation with α,β-methylene ATP to a greater degree in HF rats. In addition, HF upregulated the protein expression of kinin B2 and P2X3 in DRG and the prior application of BK increased the magnitude of α,β-methylene ATP-induced currents in muscle DRG neurons from HF rats. Conclusion: BK plays a facilitating role in modulating muscle afferent P2X-engaged reflex sympathetic and pressor responses. In HF, P2X responsivness is augmented due to increases in expression of kinin B2 and P2X3 receptors and P2X current activity.

  2. Possible role of pannexin 1/P2x7 purinoceptor in neuroprotective mechanism of ischemic postconditioning in mice.

    Science.gov (United States)

    Mahi, Namarta; Kumar, Amit; Jaggi, Amteshwar S; Singh, Nirmal; Dhawan, Ravi

    2015-06-01

    Previous studies have suggested a significant role of pannexin 1 (Panx1)/P2X7 receptor complex in cardioprotective mechanism of ischemic preconditioning and postconditioning (IPC). The present study has been undertaken to investigate whether Panx1/P2X7 purinoceptors are also involved in the neuroprotective mechanism of IPC in mice. Bilateral carotid artery occlusion (BCAO) for 12 min followed by reperfusion for 24 h was used to produce ischemia-reperfusion-induced cerebral injury in Swiss albino mice. For IPC immediately after BCAO of 12 min, three cycles of 10-s ischemia and reperfusion each were given and then prolonged reperfusion of 24 h was used. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was evaluated using a Morris water maze test. Rotarod test, inclined beam walking test, and neurologic severity score (NSS) were used to assess motor dysfunction. Acetylcholine esterase levels, brain thiobarbituric acid reactive species, and glutathione level were also estimated. BCAO followed by reperfusion produced a significant increase in cerebral infarct size, NSS along with impairment of memory and motor dysfunction. It also increased brain acetylcholine esterase, thiobarbituric acid reactive species levels, and decreased the glutathione level. IPC produced a significant decrease in the cerebral infarct size and NSS along with reversal of ischemia-reperfusion-induced impairment of memory, motor dysfunction, and altered biochemical levels in the brain. IPC-induced neuroprotective effects were significantly abolished by pretreatment of mefloquine (15.0 mg/kg orally; 30.0 mg/kg orally), blocker of Panx1/P2X7 purinoceptor. Therefore, activation of Panx1/P2X7 purinoceptors appears to play a significant role in the neuroprotective mechanism of IPC. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. P2X7 Receptor Antagonism Attenuates the Intermittent Hypoxia-induced Spatial Deficits in a Murine Model of Sleep Apnea Via Inhibiting Neuroinflammation and Oxidative Stress

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    Yan Deng

    2015-01-01

    Conclusions: The P2X7R antagonism attenuates the CIH-induced neuroinflammation, oxidative stress, and spatial deficits, demonstrating that the P2X7R is an important therapeutic target in the cognition deficits accompanied OSAS.

  4. Combined, but not individual, blockade of ASIC3, P2X, and EP4 receptors attenuates the exercise pressor reflex in rats with freely perfused hindlimb muscles.

    Science.gov (United States)

    Stone, Audrey J; Copp, Steven W; Kim, Joyce S; Kaufman, Marc P

    2015-12-01

    In healthy humans, tests of the hypothesis that lactic acid, PGE2, or ATP plays a role in evoking the exercise pressor reflex proved controversial. The findings in humans resembled ours in decerebrate rats that individual blockade of the receptors to lactic acid, PGE2, and ATP had only small effects on the exercise pressor reflex provided that the muscles were freely perfused. This similarity between humans and rats prompted us to test the hypothesis that in rats with freely perfused muscles combined receptor blockade is required to attenuate the exercise pressor reflex. We first compared the reflex before and after injecting either PPADS (10 mg/kg), a P2X receptor antagonist, APETx2 (100 μg/kg), an activating acid-sensing ion channel 3 (ASIC) channel antagonist, or L161982 (2 μg/kg), an EP4 receptor antagonist, into the arterial supply of the hindlimb of decerebrated rats. We then examined the effects of combined blockade of P2X receptors, ASIC3 channels, and EP4 receptors on the exercise pressor reflex using the same doses, intra-arterial route, and time course of antagonist injections as those used for individual blockade. We found that neither PPADS (n = 5), APETx2 (n = 6), nor L161982 (n = 6) attenuated the reflex. In contrast, combined blockade of these receptors (n = 7) attenuated the peak (↓27%, P reflex. Combined blockade injected intravenously had no effect on the reflex. We conclude that combined blockade of P2X receptors, ASIC3 channels, and EP4 receptors on the endings of thin fiber muscle afferents is required to attenuate the exercise pressor reflex in rats with freely perfused hindlimbs. Copyright © 2015 the American Physiological Society.

  5. Crystallization and preliminary X-ray diffraction analysis of two extracytoplasmic solute receptors of the DctP family from Bordetella pertussis

    International Nuclear Information System (INIS)

    Rucktooa, Prakash; Huvent, Isabelle; Antoine, Rudy; Lecher, Sophie; Jacob-Dubuisson, Françoise; Villeret, Vincent; Bompard, Coralie

    2006-01-01

    Sample preparation, crystallization and preliminary X-ray analysis are reported for two B. pertussis extracytoplasmic solute receptors. DctP6 and DctP7 are two Bordetella pertussis proteins which belong to the extracytoplasmic solute receptors (ESR) superfamily. ESRs are involved in the transport of substrates from the periplasm to the cytosol of Gram-negative bacteria. DctP6 and DctP7 have been crystallized and diffraction data were collected using a synchrotron-radiation source. DctP6 crystallized in space group P4 1 2 1 2, with unit-cell parameters a = 108.39, b = 108.39, c = 63.09 Å, while selenomethionyl-derivatized DctP7 crystallized in space group P2 1 2 1 2 1 , with unit-cell parameters a = 64.87, b = 149.83, c = 170.65 Å. The three-dimensional structure of DctP7 will be determined by single-wavelength anomalous diffraction, while the DctP6 structure will be solved by molecular-replacement methods

  6. Transmission to interneurons is via slow excitatory synaptic potentials mediated by P2Y(1 receptors during descending inhibition in guinea-pig ileum.

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    Peter D J Thornton

    Full Text Available BACKGROUND: The nature of synaptic transmission at functionally distinct synapses in intestinal reflex pathways has not been fully identified. In this study, we investigated whether transmission between interneurons in the descending inhibitory pathway is mediated by a purine acting at P2Y receptors to produce slow excitatory synaptic potentials (EPSPs. METHODOLOGY/PRINCIPAL FINDINGS: Myenteric neurons from guinea-pig ileum in vitro were impaled with intracellular microelectrodes. Responses to distension 15 mm oral to the recording site, in a separately perfused stimulation chamber and to electrical stimulation of local nerve trunks were recorded. A subset of neurons, previously identified as nitric oxide synthase immunoreactive descending interneurons, responded to both stimuli with slow EPSPs that were reversibly abolished by a high concentration of PPADS (30 μM, P2 receptor antagonist. When added to the central chamber of a three chambered organ bath, PPADS concentration-dependently depressed transmission through that chamber of descending inhibitory reflexes, measured as inhibitory junction potentials in the circular muscle of the anal chamber. Reflexes evoked by distension in the central chamber were unaffected. A similar depression of transmission was seen when the specific P2Y(1 receptor antagonist MRS 2179 (10 μM was in the central chamber. Blocking either nicotinic receptors (hexamethonium 200 μM or 5-HT(3 receptors (granisetron 1 μM together with P2 receptors had no greater effect than blocking P2 receptors alone. CONCLUSIONS/SIGNIFICANCE: Slow EPSPs mediated by P2Y(1 receptors, play a primary role in transmission between descending interneurons of the inhibitory reflexes in the guinea-pig ileum. This is the first demonstration for a primary role of excitatory metabotropic receptors in physiological transmission at a functionally identified synapse.

  7. Electroacupuncture ameliorating post-stroke cognitive impairments via inhibition of peri-infarct astroglial and microglial/macrophage P2 purinoceptors-mediated neuroinflammation and hyperplasia.

    Science.gov (United States)

    Huang, Jia; You, Xiaofang; Liu, Weilin; Song, Changming; Lin, Xiaomin; Zhang, Xiufeng; Tao, Jing; Chen, Lidian

    2017-10-10

    During ischemic stroke (IS), adenosine 5'-triphosphate (ATP) is released from damaged nerve cells of the infract core region to the extracellular space, invoking peri-infarct glial cellular P2 purinoceptors singling, and causing pro-inflammatory cytokine secretion, which is likely to initiate or aggravate motor and cognitive impairment. It has been proved that electroacupuncture (EA) is an effective and safe strategy used in anti-inflammation. However, EA for the role of purine receptors in the central nervous system has not yet been reported. Ischemia-reperfusion injured rat model was induced by middle cerebral artery occlusion and reperfusion (MCAO/R). EA treatment at the DU 20 and DU 24 acupoints treatment were conducted to rats from the 12 h after MCAO/R injury for consecutive 7 days. The neurological outcomes, infarction volumes and the level of astroglial and microglial/macrophage hyperplasia, inflammatory cytokine and P2X7R and P2Y1R expression in the peri-infarct hippocampal CA1and sensorimotor cortex were investigated after IS to evaluate the MCAO/R model and therapeutic mechanism of EA treatment. EA effectively reduced the level of pro-inflammatory cytokine interleukin-1β (IL-1β) as evidenced by reduction in astroglial and microglial/macrophage hyperplasia and the levels of P2X7R and ED1, P2X7R and GFAP, P2Y1R and ED1, P2Y1R and GFAP co-expression in peri-infarct hippocampal CA1 and sensorimotor cortex compared with that of MCAO/R model and Non-EA treatment, accompanied by the improved neurological deficit and the motor and memory impairment outcomes. Therefore, our data support the hypothesis that EA could exert its anti-inflammatory effect via inhibiting the astroglial and microglial/macrophage P2 purinoceptors (P2X7R and P2Y1R)-mediated neuroinflammation after MCAO/R injury. Astroglial and microglial/macrophage P2 purinoceptors-mediated neuroinflammation and hyperplasia in peri-infarct hippocampal CA1 and sensorimotor cortex were attenuated by EA

  8. Low-Level Laser Therapy Reduces Lung Inflammation in an Experimental Model of Chronic Obstructive Pulmonary Disease Involving P2X7 Receptor

    Directory of Open Access Journals (Sweden)

    Gabriel da Cunha Moraes

    2018-01-01

    Full Text Available Chronic obstructive pulmonary disease (COPD is a progressive disease characterized by irreversible airflow limitation, airway inflammation and remodeling, and enlargement of alveolar spaces. COPD is in the top five leading causes of deaths worldwide and presents a high economic cost. However, there are some preventive measures to lower the risk of developing COPD. Low-level laser therapy (LLLT is a new effective therapy, with very low cost and no side effects. So, our objective was to investigate if LLLT reduces pulmonary alterations in an experimental model of COPD. C57BL/6 mice were submitted to cigarette smoke for 75 days (2x/day. After 60 days to smoke exposure, the treated group was submitted to LLLT (diode laser, 660 nm, 30 mW, and 3 J/cm2 for 15 days and euthanized for morphologic and functional analysis of the lungs. Our results showed that LLLT significantly reduced the number of inflammatory cells and the proinflammatory cytokine secretion such as IL-1β, IL-6, and TNF-α in bronchoalveolar lavage fluid (BALF. We also observed that LLLT decreased collagen deposition as well as the expression of purinergic P2X7 receptor. On the other hand, LLLT increased the IL-10 release. Thus, LLLT can be pointed as a promising therapeutic approach for lung inflammatory diseases as COPD.

  9. Dorsal root ganglion neurons innervating skeletal muscle respond to physiological combinations of protons, ATP, and lactate mediated by ASIC, P2X, and TRPV1.

    Science.gov (United States)

    Light, Alan R; Hughen, Ronald W; Zhang, Jie; Rainier, Jon; Liu, Zhuqing; Lee, Jeewoo

    2008-09-01

    The adequate stimuli and molecular receptors for muscle metaboreceptors and nociceptors are still under investigation. We used calcium imaging of cultured primary sensory dorsal root ganglion (DRG) neurons from C57Bl/6 mice to determine candidates for metabolites that could be the adequate stimuli and receptors that could detect these stimuli. Retrograde DiI labeling determined that some of these neurons innervated skeletal muscle. We found that combinations of protons, ATP, and lactate were much more effective than individually applied compounds for activating rapid calcium increases in muscle-innervating dorsal root ganglion neurons. Antagonists for P2X, ASIC, and TRPV1 receptors suggested that these three receptors act together to detect protons, ATP, and lactate when presented together in physiologically relevant concentrations. Two populations of muscle-innervating DRG neurons were found. One responded to low metabolite levels (likely nonnoxious) and used ASIC3, P2X5, and TRPV1 as molecular receptors to detect these metabolites. The other responded to high levels of metabolites (likely noxious) and used ASIC3, P2X4, and TRPV1 as their molecular receptors. We conclude that a combination of ASIC, P2X5 and/or P2X4, and TRPV1 are the molecular receptors used to detect metabolites by muscle-innervating sensory neurons. We further conclude that the adequate stimuli for muscle metaboreceptors and nociceptors are combinations of protons, ATP, and lactate.

  10. Reciprocal regulation of platelet responses to P2Y and thromboxane receptor activation.

    Science.gov (United States)

    Barton, J F; Hardy, A R; Poole, A W; Mundell, S J

    2008-03-01

    Thromboxane A(2) and ADP are two major platelet agonists that stimulate two sets of G protein-coupled receptors to activate platelets. Although aggregation responses to ADP and thromboxane desensitize, there are no reports currently addressing whether activation by one agonist may heterologously desensitize responses to the other. To demonstrate whether responses to ADP or U46619 may be modulated by prior treatment of platelets with the alternate agonist, revealing a level of cross-desensitization between receptor systems. Here we show that pretreatment of platelets with either agonist substantially desensitizes aggregation responses to the other agonist. Calcium responses to thromboxane receptor activation are desensitized by preactivation of P2Y(1) but not P2Y(12) receptors. This heterologous desensitization is mediated by a protein kinase C (PKC)-independent mechanism. Reciprocally, calcium responses to ADP are desensitized by pretreatment of platelets with the thromboxane analogue, U46619, and P2Y(12)-mediated inhibition of adenylate cyclase is also desensitized by pretreatment with U46619. In this direction, desensitization is comprised of two components, a true heterologous component that is PKC-independent, and a homologous component that is mediated through stimulated release of dense granule ADP. This study reveals cross-desensitization between ADP and thromboxane receptor signaling in human platelets. Cross-desensitization is mediated by protein kinases, involving PKC-dependent and independent pathways, and indicates that alterations in the activation state of one receptor may have effects upon the sensitivity of the other receptor system.

  11. Estrogen receptor α and aryl hydrocarbon receptor cross-talk in a transfected hepatoma cell line (HepG2 exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

    Directory of Open Access Journals (Sweden)

    Manuela Göttel

    2014-01-01

    Full Text Available The prototype dioxin congener 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD is known to exert anti-estrogenic effects via activation of the aryl hydrocarbon receptor (AhR by interfering with the regulation of oestrogen homeostasis and the estrogen receptor α (ERα signalling pathway. The AhR/ER cross-talk is considered to play a crucial role in TCDD- and E2-dependent mechanisms of carcinogenesis, though the concerted mechanism of action in the liver is not yet elucidated. The present study investigated TCDD's impact on the transcriptional cross-talk between AhR and ERα and its modulation by 17β-estradiol (E2 in the human hepatoma cell line HepG2, which is AhR-responsive but ERα-negative. Transient transfection assays with co-transfection of hERα and supplementation of receptor antagonists showed anti-estrogenic action of TCDD via down-regulation of E2-induced ERα signaling. In contrast, enhancement of AhR signaling dependent on ERα was observed providing evidence for increased cytochrome P450 (CYP induction to promote E2 metabolism. However, relative mRNA levels of major E2-metabolizing CYP1A1 and 1B1 and the main E2-detoxifying catechol-O-methyltransferase were not affected by the co-treatments. This study provides new evidence of a TCDD-activated AhR-mediated molecular AhR/ERα cross-talk mechanism at transcriptional level via indirect inhibition of ERα and enhanced transcriptional activity of AhR in HepG2 cells.

  12. Liver Tumor Promotion by 2,3,7,8-Tetrachlorodibenzo-p-dioxin Is Dependent on the Aryl Hydrocarbon Receptor and TNF/IL-1 Receptors

    Science.gov (United States)

    Kennedy, Gregory D.; Nukaya, Manabu; Moran, Susan M.; Glover, Edward; Weinberg, Samuel; Balbo, Silvia; Hecht, Stephen S.; Pitot, Henry C.; Drinkwater, Norman R.; Bradfield, Christopher A.

    2014-01-01

    We set out to better understand the signal transduction pathways that mediate liver tumor promotion by 2,3,7,8-tetrachlorodibenzo-p-dioxn (“dioxin”). To this end, we first employed congenic mice homozygous for either the Ahrb1 or Ahrd alleles (encoding an aryl hydrocarbon receptor (AHR) with high or low binding affinity for dioxin, respectively) and demonstrated that hepatocellular tumor promotion in response to dioxin segregated with the Ahr locus. Once we had genetic evidence for the importance of AHR signaling, we then asked if tumor promotion by dioxin was influenced by “interleukin-1 (IL-1)-like” inflammatory cytokines. The importance of this question arose from our earlier observation that aspects of the acute hepatocellular toxicity of dioxin are dependent upon IL1-like cytokine signaling. To address this issue, we employed a triple knock-out (TKO) mouse model with null alleles at the loci encoding the three relevant receptors for tumor necrosis factors α and β and IL-1α and IL-1β (i.e., null alleles at the Tnfrsf1a, Tnfrsf1b, and Il-1r1 loci). The observation that TKO mice were resistant to the tumor promoting effects of dioxin in liver suggests that inflammatory cytokines play an important step in dioxin mediated liver tumor promotion in the mouse. Collectively, these data support the idea that the mechanism of dioxin acute hepatotoxicity and its activity as a promoter in a mouse two stage liver cancer model may be similar, i.e., tumor promotion by dioxin, like acute hepatotoxicity, are mediated by the linked action of two receptor systems, the AHR and the receptors for the “IL-1-like” cytokines. PMID:24718703

  13. The H2 receptor antagonist nizatidine is a P-glycoprotein substrate: characterization of its intestinal epithelial cell efflux transport.

    Science.gov (United States)

    Dahan, Arik; Sabit, Hairat; Amidon, Gordon L

    2009-06-01

    The aim of this study was to elucidate the intestinal epithelial cell efflux transport processes that are involved in the intestinal transport of the H(2) receptor antagonist nizatidine. The intestinal epithelial efflux transport mechanisms of nizatidine were investigated and characterized across Caco-2 cell monolayers, in the concentration range 0.05-10 mM in both apical-basolateral (AP-BL) and BL-AP directions, and the transport constants of P-glycoprotein (P-gp) efflux activity were calculated. The concentration-dependent effects of various P-gp (verapamil, quinidine, erythromycin, ketoconazole, and cyclosporine A), multidrug resistant-associated protein 2 (MRP2; MK-571, probenecid, indomethacin, and p-aminohipuric acid), and breast cancer resistance protein (BCRP; Fumitremorgin C) inhibitors on nizatidine bidirectional transport were examined. Nizatidine exhibited 7.7-fold higher BL-AP than AP-BL Caco-2 permeability, indicative of net mucosal secretion. All P-gp inhibitors investigated displayed concentration-dependent inhibition on nizatidine secretion in both directions. The IC(50) of verapamil on nizatidine P-gp secretion was 1.2 x 10(-2) mM. In the absence of inhibitors, nizatidine displayed concentration-dependent secretion, with one saturable (J(max) = 5.7 x 10(-3) nmol cm(-2) s(-1) and K(m) = 2.2 mM) and one nonsaturable component (K(d) = 7 x 10(-4) microL cm(-2) s(-1)). Under complete P-gp inhibition, nizatidine exhibited linear secretory flux, with a slope similar to the nonsaturable component. V(max) and K(m) estimated for nizatidine P-gp-mediated secretion were 4 x 10(-3) nmol cm(-2) s(-1) and 1.2 mM, respectively. No effect was obtained with the MRP2 or the BCRP inhibitors. Being a drug commonly used in pediatrics, adults, and elderly, nizatidine susceptibility to efflux transport by P-gp revealed in this paper may be of significance in its absorption, distribution, and clearance, as well as possible drug-drug interactions.

  14. Distribution of the P2X2 receptor and chemical coding in ileal enteric neurons of obese male mice (ob/ob)

    Science.gov (United States)

    Mizuno, Márcia Sanae; Crisma, Amanda Rabello; Borelli, Primavera; Schäfer, Bárbara Tavares; Silveira, Mariana Póvoa; Castelucci, Patricia

    2014-01-01

    AIM: To investigate the colocalization, density and profile of neuronal areas of enteric neurons in the ileum of male obese mice. METHODS: The small intestinal samples of male mice in an obese group (OG) (C57BL/6J ob/ob) and a control group (CG) (+/+) were used. The tissues were analyzed using a double immunostaining technique for immunoreactivity (ir) of the P2X2 receptor, nitric oxide synthase (NOS), choline acetyl transferase (ChAT) and calretinin (Calr). Also, we investigated the density and profile of neuronal areas of the NOS-, ChAT- and Calr-ir neurons in the myenteric plexus. Myenteric neurons were labeled using an NADH-diaphorase histochemical staining method. RESULTS: The analysis demonstrated that the P2X2 receptor was expressed in the cytoplasm and in the nuclear and cytoplasmic membranes only in the CG. Neuronal density values (neuron/cm2) decreased 31% (CG: 6579 ± 837; OG: 4556 ± 407) and 16.5% (CG: 7796 ± 528; OG: 6513 ± 610) in the NOS-ir and calretinin-ir neurons in the OG, respectively (P < 0.05). Density of ChAT-ir (CG: 6200 ± 310; OG: 8125 ± 749) neurons significantly increased 31% in the OG (P < 0.05). Neuron size studies demonstrated that NOS, ChAT, and Calr-ir neurons did not differ significantly between the CG and OG groups. The examination of NADH-diaphorase-positive myenteric neurons revealed an overall similarity between the OG and CG. CONCLUSION: Obesity may exert its effects by promoting a decrease in P2X2 receptor expression and modifications in the density of the NOS-ir, ChAT-ir and CalR-ir myenteric neurons. PMID:25320527

  15. Purine receptor P2Y_6 mediates cellular response to γ-ray-induced DNA damage

    International Nuclear Information System (INIS)

    Ide, Shunta; Nishimaki, Naoko; Tsukimoto, Mitsutoshi; Kojima, Shuji

    2014-01-01

    We previously showed that nucleotide P2 receptor agonists such as ATP and UTP amplify γ-ray-induced focus formation of phosphorylated histone H2A variant H2AX (γH2AX), which is considered to be an indicator of DNA damage so far, by activating purine P2Y_6 and P2Y_1_2 receptors. Therefore, we hypothesized that these P2 receptors play a role in inducing the repair response to γ-ray-induced DNA damage. In the present study, we tested this idea by using human lung cancer A549 cells. First, reverse-transcription polymerase chain reaction (RT-PCR) showed that P2Y_6 receptor is highly expressed in A549 cells, but P2Y_1_2 receptor is only weakly expressed. Next, colony formation assay revealed that P2Y_6 receptor antagonist MRS2578 markedly reduced the survival rate of γ-ray-exposed A549 cells. The survival rate was also significantly reduced in P2Y_6-knock-down cells, compared with scramble siRNA-transfected cells. Since it has reported that phosphorylation of ERK1/2 after activation of EGFR via P2Y_6 and P2Y_1_2 receptors is involved in the repair response to γ-ray-induced DNA damage, we next examined whether γ-ray-induced phosphorylation of ERK1/2 was also inhibited by MRS2578 in A549 cells. We found that it was. Taken together, these findings indicate that purinergic signaling through P2Y_6 receptor, followed by ERK1/2 activation, promotes the cellular repair response to γ-ray-induced DNA damage. (author)

  16. Crystallization and preliminary X-ray diffraction analysis of two extracytoplasmic solute receptors of the DctP family from Bordetella pertussis

    Energy Technology Data Exchange (ETDEWEB)

    Rucktooa, Prakash; Huvent, Isabelle [UMR8161 CNRS Institut de Biologie de Lille, Laboratoire de Cristallographie Macromoléculaire, 1 Rue du Professeur Calmette, BP 447, 59021 Lille CEDEX (France); IFR 142, Institut Pasteur de Lille, 1 Rue du Professeur Calmette, BP 245, 59021 Lille CEDEX (France); Antoine, Rudy; Lecher, Sophie; Jacob-Dubuisson, Françoise, E-mail: francoise.jacob@ibl.fr [IFR 142, Institut Pasteur de Lille, 1 Rue du Professeur Calmette, BP 245, 59021 Lille CEDEX (France); INSERM-U629, Lille (France); Institut Pasteur de Lille, 1 Rue du Professeur Calmette, BP 245, 59021 Lille CEDEX (France); Villeret, Vincent, E-mail: francoise.jacob@ibl.fr; Bompard, Coralie [UMR8161 CNRS Institut de Biologie de Lille, Laboratoire de Cristallographie Macromoléculaire, 1 Rue du Professeur Calmette, BP 447, 59021 Lille CEDEX (France); IFR 142, Institut Pasteur de Lille, 1 Rue du Professeur Calmette, BP 245, 59021 Lille CEDEX (France)

    2006-10-01

    Sample preparation, crystallization and preliminary X-ray analysis are reported for two B. pertussis extracytoplasmic solute receptors. DctP6 and DctP7 are two Bordetella pertussis proteins which belong to the extracytoplasmic solute receptors (ESR) superfamily. ESRs are involved in the transport of substrates from the periplasm to the cytosol of Gram-negative bacteria. DctP6 and DctP7 have been crystallized and diffraction data were collected using a synchrotron-radiation source. DctP6 crystallized in space group P4{sub 1}2{sub 1}2, with unit-cell parameters a = 108.39, b = 108.39, c = 63.09 Å, while selenomethionyl-derivatized DctP7 crystallized in space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 64.87, b = 149.83, c = 170.65 Å. The three-dimensional structure of DctP7 will be determined by single-wavelength anomalous diffraction, while the DctP6 structure will be solved by molecular-replacement methods.

  17. Liver X receptor alpha mediated genistein induction of human dehydroepiandrosterone sulfotransferase (hSULT2A1) in Hep G2 cells

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yue; Zhang, Shunfen [Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078 (United States); Zhou, Tianyan [Department of Pharmaceutics, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100083 (China); Huang, Chaoqun; McLaughlin, Alicia [Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078 (United States); Chen, Guangping, E-mail: guangping.chen@okstate.edu [Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078 (United States)

    2013-04-15

    Cytosolic sulfotransferases are one of the major families of phase II drug metabolizing enzymes. Sulfotransferase-catalyzed sulfonation regulates hormone activities, metabolizes drugs, detoxifies xenobiotics, and bioactivates carcinogens. Human dehydroepiandrosterone sulfotransferase (hSULT2A1) plays important biological roles by sulfating endogenous hydroxysteroids and exogenous xenobiotics. Genistein, mainly existing in soy food products, is a naturally occurring phytoestrogen with both chemopreventive and chemotherapeutic potential. Our previous studies have shown that genistein significantly induces hSULT2A1 in Hep G2 and Caco-2 cells. In this study, we investigated the roles of liver X receptor (LXRα) in the genistein induction of hSULT2A1. LXRs have been shown to induce expression of mouse Sult2a9 and hSULT2A1 gene. Our results demonstrate that LXRα mediates the genistein induction of hSULT2A1, supported by Western blot analysis results, hSULT2A1 promoter driven luciferase reporter gene assay results, and mRNA interference results. Chromatin immunoprecipitation (ChIP) assay results demonstrate that genistein increase the recruitment of hLXRα binding to the hSULT2A1 promoter. These results suggest that hLXRα plays an important role in the hSULT2A1 gene regulation. The biological functions of phytoestrogens may partially relate to their induction activity toward hydroxysteroid SULT. - Highlights: ► Liver X receptor α mediated genistein induction of hSULT2A1 in Hep G2 cells. ► LXRα and RXRα dimerization further activated this induction. ► Western blot results agreed well with luciferase reporter gene assay results. ► LXRs gene silencing significantly decreased hSULT2A1 expression. ► ChIP analysis suggested that genistein enhances hLXRα binding to the hSULT2A1 promoter.

  18. P2X7 signaling promotes microsphere embolism-triggered microglia activation by maintaining elevation of Fas ligand

    Directory of Open Access Journals (Sweden)

    Lu Ying-mei

    2012-07-01

    Full Text Available Abstract Background The cerebral microvascular occlusion elicits microvascular injury which mimics the different degrees of stroke severity observed in patients, but the mechanisms underlying these embolic injuries are far from understood. The Fas ligand (FasL-Fas system has been implicated in a number of pathogenic states. Here, we examined the contribution of microglia-derived FasL to brain inflammatory injury, with a focus on the potential to suppress the FasL increase by inhibition of the P2X7-FasL signaling with pharmacological or genetic approaches during ischemia. Methods The cerebral microvascular occlusion was induced by microsphere injection in experimental animals. Morphological changes in microglial cells were studied immunohistochemically. The biochemical analyses were used to examine the intracellular changes of P2X7/FasL signaling. The BV-2 cells and primary microglia from mice genetically deficient in P2X7 were used to further establish a linkage between microglia activation and FasL overproduction. Results The FasL expression was continuously elevated and was spatiotemporally related to microglia activation following microsphere embolism. Notably, P2X7 expression concomitantly increased in microglia and presented a distribution pattern that was similar to that of FasL in ED1-positive cells at pathological process of microsphere embolism. Interestingly, FasL generation in cultured microglia cells subjected to oxygen-glucose deprivation-treated neuron-conditioned medium was prevented by the silencing of P2X7. Furthermore, FasL induced the migration of BV-2 microglia, whereas the neutralization of FasL with a blocking antibody was highly effective in inhibiting ischemia-induced microglial mobility. Similar results were observed in primary microglia from wild-type mice or mice genetically deficient in P2X7. Finally, the degrees of FasL overproduction and neuronal death were consistently reduced in P2X7−/− mice compared with wild

  19. Mas-related G protein coupled receptor-X2: A potential new target for modulating mast cell-mediated allergic and inflammatory diseases.

    Science.gov (United States)

    Ali, Hydar

    2016-12-01

    Mast cells (MCs) are tissue resident immune cells that are best known for their roles in allergic and inflammatory diseases. In addition to the high affinity IgE receptor (FcεRI), MCs express numerous G protein coupled receptors (GPCRs), which are the most common targets of drug therapy. Neurokinin 1 receptor (NK-1R) is expressed on MCs and contributes to IgE and non-IgE-mediated responses in mice. Although NK-1R antagonists are highly effective in modulating experimental allergic and inflammatory responses in mice they lack efficacy in humans. This article reviews recent findings that demonstrate that while neuropeptides (NPs) activate murine MCs via NK-1R and Mas related G protein coupled receptor B2 (MrgprB2), they activate human MCs via Mas-related G protein coupled receptor X2 (MRGPRX2). Interestingly, conventional NK-1R antagonists have off-target activity against mouse MrgprB2 but not human MRGPRX2. These findings suggest that the failure to translate studies with NK-1R antagonists from in vivo mouse studies to the clinic likely reflects their lack of effect on human MRGPRX2. A unique feature of MRGPRX2 that distinguishes it from other GPCRs is that it is activated by a diverse group of ligands that include; neuropeptides, cysteine proteases, antimicrobial peptides and cationic proteins released from activated eosinophils. Thus, the development of small molecule MRGPRX2-specific antagonists or neutralizing antibodies may provide new targets for the treatment of MC-mediated allergic and inflammatory diseases.

  20. The orphan receptor ALK7 and the Activin receptor ALK4 mediate signaling by Nodal proteins during vertebrate development

    Science.gov (United States)

    Reissmann, Eva; Jörnvall, Henrik; Blokzijl, Andries; Andersson, Olov; Chang, Chenbei; Minchiotti, Gabriella; Persico, M. Graziella; Ibáñez, Carlos F.; Brivanlou, Ali H.

    2001-01-01

    Nodal proteins have crucial roles in mesendoderm formation and left–right patterning during vertebrate development. The molecular mechanisms of signal transduction by Nodal and related ligands, however, are not fully understood. In this paper, we present biochemical and functional evidence that the orphan type I serine/threonine kinase receptor ALK7 acts as a receptor for mouse Nodal and Xenopus Nodal-related 1 (Xnr1). Receptor reconstitution experiments indicate that ALK7 collaborates with ActRIIB to confer responsiveness to Xnr1 and Nodal. Both receptors can independently bind Xnr1. In addition, Cripto, an extracellular protein genetically implicated in Nodal signaling, can independently interact with both Xnr1 and ALK7, and its expression greatly enhances the ability of ALK7 and ActRIIB to respond to Nodal ligands. The Activin receptor ALK4 is also able to mediate Nodal signaling but only in the presence of Cripto, with which it can also interact directly. A constitutively activated form of ALK7 mimics the mesendoderm-inducing activity of Xnr1 in Xenopus embryos, whereas a dominant-negative ALK7 specifically blocks the activities of Nodal and Xnr1 but has little effect on other related ligands. In contrast, a dominant-negative ALK4 blocks all mesoderm-inducing ligands tested, including Nodal, Xnr1, Xnr2, Xnr4, and Activin. In agreement with a role in Nodal signaling, ALK7 mRNA is localized to the ectodermal and organizer regions of Xenopus gastrula embryos and is expressed during early stages of mouse embryonic development. Therefore, our results indicate that both ALK4 and ALK7 can mediate signal transduction by Nodal proteins, although ALK7 appears to be a receptor more specifically dedicated to Nodal signaling. PMID:11485994

  1. Crystallization and preliminary X-ray diffraction of human interleukin-7 bound to unglycosylated and glycosylated forms of its α-receptor

    Energy Technology Data Exchange (ETDEWEB)

    Wickham, Joseph Jr; Walsh, Scott T. R., E-mail: walsh.220@osu.edu [Department of Molecular and Cellular Biochemistry, Comprehensive Cancer Center, Ohio State University, 467 Hamilton Hall, 1645 Neil Avenue, Columbus, OH 43210 (United States)

    2007-10-01

    Bacterial and insect cell expression systems have been developed to produce unglycosylated and glycosylated forms of human interleukin-7 (IL-7) and the extracellular domain of its α receptor, IL-7Rα. We report the crystallization and X-ray diffraction of IL-7 complexes to both unglycosylated and glycosylated forms of the IL-7Rα to 2.7 and 3.0 Å, respectively. The interleukin-7 (IL-7) signaling pathway plays an essential role in the development, proliferation and homeostasis of T and B cells in cell-mediated immunity. Understimulation and overstimulation of the IL-7 signaling pathway leads to severe combined immunodeficiency, autoimmune reactions, heart disease and cancers. Stimulation of the IL-7 pathway begins with IL-7 binding to its α-receptor, IL-7Rα. Protein crystals of unglycosylated and glycosylated complexes of human IL-7–IL-7Rα extracellular domain (ECD) obtained using a surface entropy-reduction approach diffract to 2.7 and 3.0 Å, respectively. Anomalous dispersion methods will be used to solve the unglycosylated IL-7–IL-7Rα ECD complex structure and this unglycosylated structure will then serve as a model in molecular-replacement attempts to solve the structure of the glycosylated IL-7–α-receptor complex.

  2. Crystallization and preliminary X-ray diffraction of human interleukin-7 bound to unglycosylated and glycosylated forms of its α-receptor

    International Nuclear Information System (INIS)

    Wickham, Joseph Jr; Walsh, Scott T. R.

    2007-01-01

    Bacterial and insect cell expression systems have been developed to produce unglycosylated and glycosylated forms of human interleukin-7 (IL-7) and the extracellular domain of its α receptor, IL-7Rα. We report the crystallization and X-ray diffraction of IL-7 complexes to both unglycosylated and glycosylated forms of the IL-7Rα to 2.7 and 3.0 Å, respectively. The interleukin-7 (IL-7) signaling pathway plays an essential role in the development, proliferation and homeostasis of T and B cells in cell-mediated immunity. Understimulation and overstimulation of the IL-7 signaling pathway leads to severe combined immunodeficiency, autoimmune reactions, heart disease and cancers. Stimulation of the IL-7 pathway begins with IL-7 binding to its α-receptor, IL-7Rα. Protein crystals of unglycosylated and glycosylated complexes of human IL-7–IL-7Rα extracellular domain (ECD) obtained using a surface entropy-reduction approach diffract to 2.7 and 3.0 Å, respectively. Anomalous dispersion methods will be used to solve the unglycosylated IL-7–IL-7Rα ECD complex structure and this unglycosylated structure will then serve as a model in molecular-replacement attempts to solve the structure of the glycosylated IL-7–α-receptor complex

  3. Important roles of P2Y receptors in the inflammation and cancer of digestive system

    OpenAIRE

    Wan, Han-Xing; Hu, Jian-Hong; Xie, Rei; Yang, Shi-Ming; Dong, Hui

    2016-01-01

    Purinergic signaling is important for many biological processes in humans. Purinoceptors P2Y are widely distributed in human digestive system and different subtypes of P2Y receptors mediate different physiological functions from metabolism, proliferation, differentiation to apoptosis etc. The P2Y receptors are essential in many gastrointestinal functions and also involve in the occurrence of some digestive diseases. Since different subtypes of P2Y receptors are present on the same cell of dig...

  4. Understanding the role of P2X7 in affective disorders – are glial cells the major players?

    Directory of Open Access Journals (Sweden)

    Leanne eStokes

    2015-07-01

    Full Text Available The pathophysiology of several psychiatric disorders has been linked to biomarkers of inflammation generating a theory of major depressive disorder as an inflammatory disease and infection and autoimmunity as major risk factors for schizophrenia. The idea of pro-inflammatory cytokines altering behavior is now well accepted however many questions remain. Microglia can produce a plethora of inflammatory cytokines and these cells appear to be critical in the link between inflammatory changes and depressive disorders. Microglia play a known role in sickness behavior which has many components of depressive-like behavior such as social withdrawal, sleep alterations, and anorexia. Numerous candidate genes have been identified for psychiatric disorders in the last decade. Single nucleotide polymorphisms in the human P2X7 gene have been linked to bipolar disorder, depression, and to the severity of depressive symptoms. P2X7 is a ligand-gated cation channel expressed on microglia with lower levels found on astrocytes and on some neuronal populations. In microglia P2X7 is a major regulator of pro-inflammatory cytokines of the interleukin-1 family. Genetic deletion of P2X7 in mice is protective for depressive behavior in addition to inflammatory responses. P2X7-/- mice have been shown to demonstrate anti-depressive-like behavior in forced swim and tail suspension behavioral tests and stressor-induced behavioral responses were blunted. Both neurochemical (norepinephrine, serotonin, dopamine and inflammatory changes have been observed in the brains of P2X7-/- mice. This review will discuss the recent evidence for involvement of P2X7 in the pathophysiology of depressive disorders and propose mechanisms by which altered signaling through this ion channel may affect the inflammatory state of the brain.

  5. Influence of ER leak on resting cytoplasmic Ca2+ and receptor-mediated Ca2+ signalling in human macrophage.

    Science.gov (United States)

    Layhadi, Janice A; Fountain, Samuel J

    2017-06-03

    Mechanisms controlling endoplasmic reticulum (ER) Ca 2+ homeostasis are important regulators of resting cytoplasmic Ca 2+ concentration ([Ca 2+ ] cyto ) and receptor-mediated Ca 2+ signalling. Here we investigate channels responsible for ER Ca 2+ leak in THP-1 macrophage and human primary macrophage. In the absence of extracellular Ca 2+ we employ ionomycin action at the plasma membrane to stimulate ER Ca 2+ leak. Under these conditions ionomycin elevates [Ca 2+ ] cyto revealing a Ca 2+ leak response which is abolished by thapsigargin. IP 3 receptors (Xestospongin C, 2-APB), ryanodine receptors (dantrolene), and translocon (anisomycin) inhibition facilitated ER Ca 2+ leak in model macrophage, with translocon inhibition also reducing resting [Ca 2+ ] cyto . In primary macrophage, translocon inhibition blocks Ca 2+ leak but does not influence resting [Ca 2+ ] cyto . We identify a role for translocon-mediated ER Ca 2+ leak in receptor-mediated Ca 2+ signalling in both model and primary human macrophage, whereby the Ca 2+ response to ADP (P2Y receptor agonist) is augmented following anisomycin treatment. In conclusion, we demonstrate a role of ER Ca 2+ leak via the translocon in controlling resting cytoplasmic Ca 2+ in model macrophage and receptor-mediated Ca 2+ signalling in model macrophage and primary macrophage. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Functional expression of ionotropic purinergic receptors on mouse taste bud cells.

    Science.gov (United States)

    Hayato, Ryotaro; Ohtubo, Yoshitaka; Yoshii, Kiyonori

    2007-10-15

    Neurotransmitter receptors on taste bud cells (TBCs) and taste nerve fibres are likely to contribute to taste transduction by mediating the interaction among TBCs and that between TBCs and taste nerve fibres. We investigated the functional expression of P2 receptor subtypes on TBCs of mouse fungiform papillae. Electrophysiological studies showed that 100 microm ATP applied to their basolateral membranes either depolarized or hyperpolarized a few cells per taste bud. Ca(2+) imaging showed that similarly applied 1 mum ATP, 30 microm BzATP (a P2X(7) agonist), or 1 microm 2MeSATP (a P2Y(1) and P2Y(11) agonist) increased intracellular Ca(2+) concentration, but 100 microm UTP (a P2Y(2) and P2Y(4) agonist) and alpha,beta-meATP (a P2X agonist except for P2X(2), P2X(4) and P2X(7)) did not. RT-PCR suggested the expression of P2X(2), P2X(4), P2X(7), P2Y(1), P2Y(13) and P2Y(14) among the seven P2X subtypes and seven P2Y subtypes examined. Immunohistostaining confirmed the expression of P2X(2). The exposure of the basolateral membranes to 3 mm ATP for 30 min caused the uptake of Lucifer Yellow CH in a few TBCs per taste bud. This was antagonized by 100 microm PPADS (a non-selective P2 blocker) and 1 microm KN-62 (a P2X(7) blocker). These results showed for the first time the functional expression of P2X(2) and P2X(7) on TBCs. The roles of P2 receptor subtypes in the taste transduction, and the renewal of TBCs, are discussed.

  7. P2Y6 receptor potentiates pro-inflammatory responses in macrophages and exhibits differential roles in atherosclerotic lesion development.

    Directory of Open Access Journals (Sweden)

    Ricardo A Garcia

    Full Text Available BACKGROUND: P2Y(6, a purinergic receptor for UDP, is enriched in atherosclerotic lesions and is implicated in pro-inflammatory responses of key vascular cell types and macrophages. Evidence for its involvement in atherogenesis, however, has been lacking. Here we use cell-based studies and three murine models of atherogenesis to evaluate the impact of P2Y(6 deficiency on atherosclerosis. METHODOLOGY/PRINCIPAL FINDINGS: Cell-based studies in 1321N1 astrocytoma cells, which lack functional P2Y(6 receptors, showed that exogenous expression of P2Y(6 induces a robust, receptor- and agonist-dependent secretion of inflammatory mediators IL-8, IL-6, MCP-1 and GRO1. P2Y(6-mediated inflammatory responses were also observed, albeit to a lesser extent, in macrophages endogenously expressing P2Y(6 and in acute peritonitis models of inflammation. To evaluate the role of P2Y(6 in atherosclerotic lesion development, we used P2Y(6-deficient mice in three mouse models of atherosclerosis. A 43% reduction in aortic arch plaque was observed in high fat-fed LDLR knockout mice lacking P2Y(6 receptors in bone marrow-derived cells. In contrast, no effect on lesion development was observed in fat-fed whole body P2Y(6xLDLR double knockout mice. Interestingly, in a model of enhanced vascular inflammation using angiotensin II, P2Y(6 deficiency enhanced formation of aneurysms and exhibited a trend towards increased atherosclerosis in the aorta of LDLR knockout mice. CONCLUSIONS: P2Y(6 receptor augments pro-inflammatory responses in macrophages and exhibits a pro-atherogenic role in hematopoietic cells. However, the overall impact of whole body P2Y(6 deficiency on atherosclerosis appears to be modest and could reflect additional roles of P2Y(6 in vascular disease pathophysiologies, such as aneurysm formation.

  8. Concomitant alteration in number and affinity of P2X and muscarinic receptors are associated with bladder dysfunction in early stage of diabetic rats.

    Science.gov (United States)

    Yoshizawa, Tsuyoshi; Hayashi, Yukio; Yoshida, Akira; Yoshida, Shohei; Ito, Yoshihiko; Yamaguchi, Kenya; Yamada, Shizuo; Takahashi, Satoru

    2018-03-01

    To investigate time course of bladder dysfunction and concurrent changes in number and affinity of the muscarinic and P 2 X receptor in the early stage of streptozotocin (STZ)-induced diabetic rats. Diabetic rats were prepared by the intraperitoneal injection of 50 mg/kg of STZ to 7-week-old female Wistar rats. We performed recording of 24-h voiding behavior and cystometry at 1, 4, 8, and 12 weeks after the induction of diabetes. A muscle strip experiments with electrical field stimulation (EFS), carbachol, and α,β-methylene adenosine 5'-triphosphate (α,β-MeATP) were also performed at the same time-points. Additionally, concurrent changes in number and affinity of bladder muscarinic and P 2 X receptor were measured by a radioreceptor assay using [N-methyl- 3 H] scopolamine methyl chloride ([ 3 H]NMS) and α,β-methylene-ATP (2,8- 3 H) tetrasodium salt ([ 3 H]α,β-MeATP). In STZ-induced diabetic rats, polydipsic polyuric pollakiuria were noted on recording of 24-h voiding behavior from early stage. Also, the residual urine volume markedly increased in diabetic rats on cystometry. In the muscle strip experiment, the detrusor contractions induced by EFS, carbachol, and α,β-MeATP were enhanced in STZ-induced diabetic rats. Based on the radioreceptor assay, the maximum number of sites (Bmax) for the specific binding of [ 3 H]NMS and [ 3 H]α,β-MeATP was concurrently increased in the bladder from diabetic rats. Increased bladder contractility is found in early stage of diabetic rats. Then, bladder dysfunction is associated with increased number of muscarinic and P 2 X receptors in STZ-induced diabetic rats.

  9. Endocrine disruptors induce cytochrome P450 by affecting transcriptional regulation via pregnane X receptor

    International Nuclear Information System (INIS)

    Mikamo, Eriko; Harada, Shingo; Nishikawa, Jun-ichi; Nishihara, Tsutomu

    2003-01-01

    Pregnane X receptor (PXR) is a nuclear receptor that regulates the expression of genes for cytochrome P450 3A (CYP3A), multidrug resistance 1 (MDR1), and organic anion-transporting peptide 2 (OATP2). These genes control the metabolism (CYP3A subfamily) and aspects of the pharmacokinetics (MDR1 and OATP2) of both endogenous and xenobiotic compounds. Since PXR is important in understanding the actions of endocrine disruptors (EDs), we determined the ability of suspected EDs to interact with PXR. In our study, 7 of 54 xenobiotics compounds interacted with PXR, including methoxychlor and benzophenone. All of the chemicals activated PXR in vitro and induced CYP3A mRNA in the male rat liver. In addition, CYP2C11 was also induced by some PXR agonists and converted methoxychlor into xenoestrogen. These findings suggest that some EDs affect sex hormone receptor indirectly by induction of metabolic enzyme via PXR, to produce rapidly higher concentrations of effective metabolites, leading to disturbance of the endocrine system

  10. Controlled phase stability of highly Na-active triclinic structure in nanoscale high-voltage Na2-2xCo1+xP2O7 cathode for Na-ion batteries

    Science.gov (United States)

    Song, Hee Jo; Kim, Jae-Chan; Dar, Mushtaq Ahmad; Kim, Dong-Wan

    2018-02-01

    With the increasing demand for high energy density in energy-storage systems, a high-voltage cathode is essential in rechargeable Li-ion and Na-ion batteries. The operating voltage of a triclinic-polymorph Na2CoP2O7, also known as the rose form, is above 4.0 V (vs. Na/Na+), which is relatively high compared to that of other cathode materials. Thus, it can be employed as a potential high-voltage cathode material in Na-ion batteries. However, it is difficult to synthesize a pure rose phase because of its low phase stability, thus limiting its use in high-voltage applications. Herein, compositional-engineered, rose-phase Na2-2xCo1+xP2O7/C (x = 0, 0.1 and 0.2) nanopowder are prepared using a wet-chemical method. The Na2-2xCo1+xP2O7/C cathode shows high electrochemical reactivity with Na ions at 4.0 V, delivering high capacity and high energy density.

  11. The aryl hydrocarbon receptor and estrogen receptor alpha differentially modulate nuclear factor erythroid-2-related factor 2 transactivation in MCF-7 breast cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Lo, Raymond; Matthews, Jason, E-mail: jason.matthews@utoronto.ca

    2013-07-15

    Nuclear factor erythroid-2-related factor 2 (NRF2; NFE2L2) plays an important role in mediating cellular protection against reactive oxygen species. NRF2 signaling is positively modulated by the aryl hydrocarbon receptor (AHR) but inhibited by estrogen receptor alpha (ERα). In this study we investigated the crosstalk among NRF2, AHR and ERα in MCF-7 breast cancer cells treated with the NRF2 activator sulforaphane (SFN), a dual AHR and ERα activator, 3,3′-diindolylmethane (DIM), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or 17β-estradiol (E2). SFN-dependent increases in NADPH-dependent oxidoreductase 1 (NQO1) and heme oxygenase I (HMOX1) mRNA levels were significantly reduced after co-treatment with E2. E2-dependent repression of NQO1 and HMOX1 was associated with increased ERα but reduced p300 recruitment and reduced histone H3 acetylation at both genes. In contrast, DIM + SFN or TCDD + SFN induced NQO1 and HMOX1 mRNA expression to levels higher than SFN alone, which was prevented by RNAi-mediated knockdown of AHR. DIM + SFN but not TCDD + SFN also induced recruitment of ERα to NQO1 and HMOX1. However, the presence of AHR at NQO1 and HMOX1 restored p300 recruitment and histone H3 acetylation, thereby reversing the ERα-dependent repression of NRF2. Taken together, our study provides further evidence of functional interplay among NRF2, AHR and ERα signaling pathways through altered p300 recruitment to NRF2-regulated target genes. - Highlights: • We examined crosstalk among ERα, AHR, and NRF2 in MCF-7 breast cancer cells. • AHR enhanced the mRNA expression levels of two NRF2 target genes – HMOX1 and NQO1. • ERα repressed HMOX1 and NQO1 expression via decreased histone acetylation. • AHR prevented ERα-dependent repression of HMOX1 and NQO1.

  12. The aryl hydrocarbon receptor and estrogen receptor alpha differentially modulate nuclear factor erythroid-2-related factor 2 transactivation in MCF-7 breast cancer cells

    International Nuclear Information System (INIS)

    Lo, Raymond; Matthews, Jason

    2013-01-01

    Nuclear factor erythroid-2-related factor 2 (NRF2; NFE2L2) plays an important role in mediating cellular protection against reactive oxygen species. NRF2 signaling is positively modulated by the aryl hydrocarbon receptor (AHR) but inhibited by estrogen receptor alpha (ERα). In this study we investigated the crosstalk among NRF2, AHR and ERα in MCF-7 breast cancer cells treated with the NRF2 activator sulforaphane (SFN), a dual AHR and ERα activator, 3,3′-diindolylmethane (DIM), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or 17β-estradiol (E2). SFN-dependent increases in NADPH-dependent oxidoreductase 1 (NQO1) and heme oxygenase I (HMOX1) mRNA levels were significantly reduced after co-treatment with E2. E2-dependent repression of NQO1 and HMOX1 was associated with increased ERα but reduced p300 recruitment and reduced histone H3 acetylation at both genes. In contrast, DIM + SFN or TCDD + SFN induced NQO1 and HMOX1 mRNA expression to levels higher than SFN alone, which was prevented by RNAi-mediated knockdown of AHR. DIM + SFN but not TCDD + SFN also induced recruitment of ERα to NQO1 and HMOX1. However, the presence of AHR at NQO1 and HMOX1 restored p300 recruitment and histone H3 acetylation, thereby reversing the ERα-dependent repression of NRF2. Taken together, our study provides further evidence of functional interplay among NRF2, AHR and ERα signaling pathways through altered p300 recruitment to NRF2-regulated target genes. - Highlights: • We examined crosstalk among ERα, AHR, and NRF2 in MCF-7 breast cancer cells. • AHR enhanced the mRNA expression levels of two NRF2 target genes – HMOX1 and NQO1. • ERα repressed HMOX1 and NQO1 expression via decreased histone acetylation. • AHR prevented ERα-dependent repression of HMOX1 and NQO1.

  13. Sphingosine-1-phosphate (S1P) displays sustained S1P1 receptor agonism and signaling through S1P lyase-dependent receptor recycling.

    Science.gov (United States)

    Gatfield, John; Monnier, Lucile; Studer, Rolf; Bolli, Martin H; Steiner, Beat; Nayler, Oliver

    2014-07-01

    The sphingosine-1-phosphate (S1P) type 1 receptor (S1P1R) is a novel therapeutic target in lymphocyte-mediated autoimmune diseases. S1P1 receptor desensitization caused by synthetic S1P1 receptor agonists prevents T-lymphocyte egress from secondary lymphoid organs into the circulation. The selective S1P1 receptor agonist ponesimod, which is in development for the treatment of autoimmune diseases, efficiently reduces peripheral lymphocyte counts and displays efficacy in animal models of autoimmune disease. Using ponesimod and the natural ligand S1P, we investigated the molecular mechanisms leading to different signaling, desensitization and trafficking behavior of S1P1 receptors. In recombinant S1P1 receptor-expressing cells, ponesimod and S1P triggered Gαi protein-mediated signaling and β-arrestin recruitment with comparable potency and efficiency, but only ponesimod efficiently induced intracellular receptor accumulation. In human umbilical vein endothelial cells (HUVEC), ponesimod and S1P triggered translocation of the endogenous S1P1 receptor to the Golgi compartment. However, only ponesimod treatment caused efficient surface receptor depletion, receptor accumulation in the Golgi and degradation. Impedance measurements in HUVEC showed that ponesimod induced only short-lived Gαi protein-mediated signaling followed by resistance to further stimulation, whereas S1P induced sustained Gαi protein-mediated signaling without desensitization. Inhibition of S1P lyase activity in HUVEC rendered S1P an efficient S1P1 receptor internalizing compound and abrogated S1P-mediated sustained signaling. This suggests that S1P lyase - by facilitating S1P1 receptor recycling - is essential for S1P-mediated sustained signaling, and that synthetic agonists are functional antagonists because they are not S1P lyase substrates. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. The brain cytoplasmic RNA BC1 regulates dopamine D2 receptor-mediated transmission in the striatum.

    Science.gov (United States)

    Centonze, Diego; Rossi, Silvia; Napoli, Ilaria; Mercaldo, Valentina; Lacoux, Caroline; Ferrari, Francesca; Ciotti, Maria Teresa; De Chiara, Valentina; Prosperetti, Chiara; Maccarrone, Mauro; Fezza, Filomena; Calabresi, Paolo; Bernardi, Giorgio; Bagni, Claudia

    2007-08-15

    Dopamine D(2) receptor (D(2)DR)-mediated transmission in the striatum is remarkably flexible, and changes in its efficacy have been heavily implicated in a variety of physiological and pathological conditions. Although receptor-associated proteins are clearly involved in specific forms of synaptic plasticity, the molecular mechanisms regulating the sensitivity of D(2) receptors in this brain area are essentially obscure. We have studied the physiological responses of the D(2)DR stimulations in mice lacking the brain cytoplasmic RNA BC1, a small noncoding dendritically localized RNA that is supposed to play a role in mRNA translation. We show that the efficiency of D(2)-mediated transmission regulating striatal GABA synapses is under the control of BC1 RNA, through a negative influence on D(2) receptor protein level affecting the functional pool of receptors. Ablation of the BC1 gene did not result in widespread dysregulation of synaptic transmission, because the sensitivity of cannabinoid CB(1) receptors was intact in the striatum of BC1 knock-out (KO) mice despite D(2) and CB(1) receptors mediated similar electrophysiological actions. Interestingly, the fragile X mental retardation protein FMRP, one of the multiple BC1 partners, is not involved in the BC1 effects on the D(2)-mediated transmission. Because D(2)DR mRNA is apparently equally translated in the BC1-KO and wild-type mice, whereas the protein level is higher in BC1-KO mice, we suggest that BC1 RNA controls D(2)DR indirectly, probably regulating translation of molecules involved in D(2)DR turnover and/or stability.

  15. Sp1/3 and NF-1 mediate basal transcription of the human P2X1 gene in megakaryoblastic MEG-01 cells

    Directory of Open Access Journals (Sweden)

    Ennion Steven J

    2006-03-01

    Full Text Available Abstract Background P2X1 receptors play an important role in platelet function as they can induce shape change, granule centralization and are also involved in thrombus formation. As platelets have no nuclei, the level of P2X1 expression depends on transcriptional regulation in megakaryocytes, the platelet precursor cell. Since nothing is known about the molecular mechanisms regulating megakaryocytic P2X1 expression, this study aimed to identify and functionally characterize the P2X1 core promoter utilized in the human megakaryoblastic cell line MEG-01. Results In order to identify cis-acting elements involved in the transcriptional regulation of P2X1 expression, the ability of 4.7 kb P2X1 upstream sequence to drive luciferase reporter gene expression was tested. Low promoter activity was detected in proliferating MEG-01 cells. This activity increased 20-fold after phorbol-12-myristate-13-acetate (PMA induced differentiation. A transcription start site was detected 365 bp upstream of the start codon by primer extension. Deletion analysis of reporter constructs indicated a core promoter located within the region -68 to +149 bp that contained two Sp1 sites (named Sp1a and Sp1b and an NF-1 site. Individual mutations of Sp1b or NF-1 binding sites severely reduced promoter activity whereas triple mutation of Sp1a, Sp1b and NF-1 sites completely abolished promoter activity in both untreated and PMA treated cells. Sp1/3 and NF-1 proteins were shown to bind their respective sites by EMSA and interaction of Sp1/3, NF-1 and TFIIB with the endogenous P2X1 core promoter in MEG-01 cells was demonstrated by chromatin immunoprecipitation. Alignment of P2X1 genes from human, chimp, rat, mouse and dog revealed consensus Sp1a, Sp1b and NF-1 binding sites in equivalent positions thereby demonstrating evolutionary conservation of these functionally important sites. Conclusion This study has identified and characterized the P2X1 promoter utilized in MEG-01 cells and

  16. Correlation between Urothelial Differentiation and Sensory Proteins P2X3, P2X5, TRPV1, and TRPV4 in Normal Urothelium and Papillary Carcinoma of Human Bladder

    Directory of Open Access Journals (Sweden)

    Igor Sterle

    2014-01-01

    Full Text Available Terminal differentiation of urothelium is a prerequisite for blood-urine barrier formation and enables normal sensory function of the urinary bladder. In this study, urothelial differentiation of normal human urothelium and of low and high grade papillary urothelial carcinomas was correlated with the expression and localization of purinergic receptors (P2X3, and P2X5 and transient receptor potential vanilloid channels (TRPV1, and TRPV4. Western blotting and immunofluorescence of uroplakins together with scanning electron microscopy of urothelial apical surface demonstrated terminal differentiation of normal urothelium, partial differentiation of low grade carcinoma, and poor differentiation of high grade carcinoma. P2X3 was expressed in normal urothelium as well as in low grade carcinoma and in both cases immunolabeling was stronger in the superficial cells. P2X3 expression decreased in high grade carcinoma. P2X5 expression was detected in normal urothelium and in high grade carcinoma, while in low grade carcinoma its expression was diminished. The expression of TRPV1 decreased in low grade and even more in high grade carcinoma when compared with normal urothelium, while TRPV4 expression was unchanged in all samples. Our results suggest that sensory proteins P2X3 and TRPV1 are in correlation with urothelial differentiation, while P2X5 and TRPV4 have unique expression patterns.

  17. P2Y purinoceptor and nucleotide receptor-induced relaxation of precontracted bovine aortic collateral artery rings: differential sensitivity to suramin and indomethacin.

    Science.gov (United States)

    Wilkinson, G F; McKechnie, K; Dainty, I A; Boarder, M R

    1994-02-01

    We have examined a series of adenine nucleotides and UTP for their ability to cause relaxation of precontracted bovine aortic collateral artery rings. The overall rank order of agonist potency for relaxation was 2-methylthioadenosine 5'-triphosphate (2MeSATP) > adenosine 5'-O-(3-thiotriphosphate) (ATP gamma S) > UTP > ADP > ATP. These responses were endothelium-dependent. Interaction studies showed that responses to the selective P2Y purinoceptor agonist 2MeSATP, and to ADP, were mediated by different receptors from those mediating responses to UTP. Suramin, a P2 purinoceptor antagonist that binds to diverse sites for ATP, produced a concentration-dependent shift in the agonist concentration-effect curve to 2MeSATP, with a pKB of 5.45 +/- 0.15 and a slope of 0.94 +/- 0.09. Suramin produced a small, nonsignificant shift in the UTP response curve and had little effect on responses to ATP. Indomethacin (2.8 x 10(-6) M) had no effect on concentration-effect curves to UTP but almost abolished the relaxations produced by 2MeSATP and ADP. The concentration-effect curves to ATP and ATP gamma S showed a significant (P effects of indomethacin show that these receptors differentially modulate the release of cyclooxygenase-derived mediators of relaxation.

  18. X-ray absorption spectroscopy of single-crystalline (VO)2P2O7: Electronic structure and possible exchange paths

    International Nuclear Information System (INIS)

    Gerhold, S.; Nu''cker, N.; Kuntscher, C. A.; Schuppler, S.; Stadler, S.; Idzerda, Y. U.; Prokofiev, A. V.; Bu''llesfeld, F.; Assmus, W.

    2001-01-01

    Using polarization-dependent V2p and O1s near-edge x-ray absorption spectroscopy, we studied the unoccupied electronic structure of single-crystalline (VO) 2 P 2 O 7 . It is highly anisotropic, and shows similarities to vanadium oxides like VO 2 and V 2 O 5 at the V2p edge and at the O1s threshold. The contributions from V-O and P-O orbitals could be identified. The results rule out the spin ladder model for the magnetic behavior of (VO) 2 P 2 O 7 , but are consistent with the alternating chain scenario

  19. Neuroprotection of rat retinal ganglion cells mediated through alpha7 nicotinic acetylcholine receptors.

    Science.gov (United States)

    Iwamoto, K; Mata, D; Linn, D M; Linn, C L

    2013-05-01

    Glutamate-induced excitotoxicity is thought to play an important role in several neurodegenerative diseases in the central nervous system (CNS). In this study, neuroprotection against glutamate-induced excitotoxicity was analyzed using acetylcholine (ACh), nicotine and the α7 specific nicotinic acetylcholine receptor7 nAChR) agonist, N-[(3R)-1-azabicyclo[2.2.2]oct-3-yl]-4-chlorobenzamide hydrochloride (PNU-282987), in cultured adult rat retinal neurons. Adult Long Evans rat retinas were dissociated and retinal ganglion cells (RGCs) were isolated from all other retinal tissue using a two-step panning technique. Once isolated, RGCs were cultured under various pharmacological conditions to demonstrate excitotoxicity and neuroprotection against excitotoxicity. After 3 days, RGCs were immunostained with antibodies against the glycoprotein, Thy 1.1, counted and cell survival was assessed relative to control untreated conditions. 500 μM glutamate induced excitotoxicity in large and small RGCs in an adult rat dissociated culture. After 3 days in culture with glutamate, the cell survival of large RGCs decreased by an average of 48.16% while the cell survival of small RGCs decreased by an average of 42.03%. Using specific glutamate receptor agonists and antagonists, we provide evidence that the excitotoxic response was mediated through α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainic acid (KA) and N-methyl-d-aspartate (NMDA) glutamate receptors through an apoptotic mechanism. However, the excitotoxic effect of glutamate on all RGCs was eliminated if cells were cultured for an hour with 10 μM ACh, 100 μM nicotine or 100 nM of the α7 nAChR agonist, PNU-282987, before the glutamate insult. Inhibition studies using 10nM methyllycaconitine (MLA) or α-bungarotoxin (α-Bgt) supported the hypothesis that neuroprotection against glutamate-induced excitotoxicity on rat RGCs was mediated through α7 nAChRs. In immunocytochemical studies, double

  20. The nuclear localization of low risk HPV11 E7 protein mediated by its zinc binding domain is independent of nuclear import receptors

    International Nuclear Information System (INIS)

    Piccioli, Zachary; McKee, Courtney H.; Leszczynski, Anna; Onder, Zeynep; Hannah, Erin C.; Mamoor, Shahan; Crosby, Lauren; Moroianu, Junona

    2010-01-01

    We investigated the nuclear import of low risk HPV11 E7 protein using 1) transfection assays in HeLa cells with EGFP fusion plasmids containing 11E7 and its domains and 2) nuclear import assays in digitonin-permeabilized HeLa cells with GST fusion proteins containing 11E7 and its domains. The EGFP-11E7 and EGFP-11cE7 39-98 localized mostly to the nucleus. The GST-11E7 and GST-11cE7 39-98 were imported into the nuclei in the presence of either Ran-GDP or RanG19V-GTP mutant and in the absence of nuclear import receptors. This suggests that 11E7 enters the nucleus via a Ran-dependent pathway, independent of nuclear import receptors, mediated by a nuclear localization signal located in its C-terminal domain (cNLS). This cNLS contains the zinc binding domain consisting of two copies of Cys-X-X-Cys motif. Mutagenesis of Cys residues in these motifs changed the localization of the EGFP-11cE7/-11E7 mutants to cytoplasmic, suggesting that the zinc binding domain is essential for nuclear localization of 11E7.

  1. ATP mediates NADPH oxidase/ROS generation and COX-2/PGE2 expression in A549 cells: role of P2 receptor-dependent STAT3 activation.

    Directory of Open Access Journals (Sweden)

    Shin-Ei Cheng

    Full Text Available BACKGROUND: Up-regulation of cyclooxygenase (COX-2 and its metabolite prostaglandin E(2 (PGE(2 are frequently implicated in lung inflammation. Extracellular nucleotides, such as ATP have been shown to act via activation of P2 purinoceptors, leading to COX-2 expression in various inflammatory diseases, such as lung inflammation. However, the mechanisms underlying ATP-induced COX-2 expression and PGE(2 release remain unclear. PRINCIPAL FINDINGS: Here, we showed that ATPγS induced COX-2 expression in A549 cells revealed by western blot and real-time PCR. Pretreatment with the inhibitors of P2 receptor (PPADS and suramin, PKC (Gö6983, Gö6976, Ro318220, and Rottlerin, ROS (Edaravone, NADPH oxidase [diphenyleneiodonium chloride (DPI and apocynin], Jak2 (AG490, and STAT3 [cucurbitacin E (CBE] and transfection with siRNAs of PKCα, PKCι, PKCμ, p47(phox, Jak2, STAT3, and cPLA(2 markedly reduced ATPγS-induced COX-2 expression and PGE(2 production. In addition, pretreatment with the inhibitors of P2 receptor attenuated PKCs translocation from the cytosol to the membrane in response to ATPγS. Moreover, ATPγS-induced ROS generation and p47(phox translocation was also reduced by pretreatment with the inhibitors of P2 receptor, PKC, and NADPH oxidase. On the other hand, ATPγS stimulated Jak2 and STAT3 activation which were inhibited by pretreatment with PPADS, suramin, Gö6983, Gö6976, Ro318220, GF109203X, Rottlerin, Edaravone, DPI, and apocynin in A549 cells. SIGNIFICANCE: Taken together, these results showed that ATPγS induced COX-2 expression and PGE(2 production via a P2 receptor/PKC/NADPH oxidase/ROS/Jak2/STAT3/cPLA(2 signaling pathway in A549 cells. Increased understanding of signal transduction mechanisms underlying COX-2 gene regulation will create opportunities for the development of anti-inflammation therapeutic strategies.

  2. Selectivity and specificity of sphingosine-1-phosphate receptor ligands: caveats and critical thinking in characterizing receptor-mediated effects.

    Science.gov (United States)

    Salomone, Salvatore; Waeber, Christian

    2011-01-01

    Receptors for sphingosine-1-phosphate (S1P) have been identified only recently. Their medicinal chemistry is therefore still in its infancy, and few selective agonists or antagonists are available. Furthermore, the selectivity of S1P receptor agonists or antagonists is not well established. JTE-013 and BML-241 (also known as CAY10444), used extensively as specific S1P(2) and S1P(3) receptors antagonists respectively, are cases in point. When analyzing S1P-induced vasoconstriction in mouse basilar artery, we observed that JTE-013 inhibited not only the effect of S1P, but also the effect of U46619, endothelin-1 or high KCl; JTE-013 strongly inhibited responses to S1P in S1P(2) receptor knockout mice. Similarly, BML-241 has been shown to inhibit increases in intracellular Ca(2+) concentration via P(2) receptor or α(1A)-adrenoceptor stimulation and α(1A)-adrenoceptor-mediated contraction of rat mesenteric artery, while it did not affect S1P(3)-mediated decrease of forskolin-induced cyclic AMP accumulation. Another putative S1P(1/3) receptor antagonist, VPC23019, does not inhibit S1P(3)-mediated vasoconstriction. With these examples in mind, we discuss caveats about relying on available pharmacological tools to characterize receptor subtypes.

  3. Selectivity and specificity of sphingosine-1-phosphate receptor ligands: caveats and critical thinking in characterizing receptor-mediated effects

    Directory of Open Access Journals (Sweden)

    Christian eWaeber

    2011-02-01

    Full Text Available Receptors for sphingosine-1-phosphate (S1P have been identified only recently. Their medicinal chemistry is therefore still in its infancy, and few selective agonists or antagonists are available. Furthermore, the selectivity of S1P receptor agonists or antagonists is not well established. JTE-013 and BML-241 (also known as CAY10444, used extensively as specific S1P2 and S1P3 receptors antagonists respectively, are cases in point. When analyzing S1P-induced vasoconstriction in mouse basilar artery, we observed that JTE-013 inhibited not only the effect of S1P, but also the effect of U46619, endothelin-1 or high KCl; JTE-013 strongly inhibited responses to S1P in S1P2 receptor knockout mice. Similarly, BML-241 has been shown to inhibit increases in intracellular Ca2+ concentration via P2 receptor or α1A-adrenoceptor stimulation and α1A-adrenoceptor-mediated contraction of rat mesenteric artery, while it did not affect S1P3-mediated decrease of forskolin-induced cyclic AMP accumulation. Another putative S1P1/3 receptor antagonist, VPC23019, does not inhibit S1P3-mediated vasoconstriction. With these examples in mind, we discuss caveats about relying on available pharmacological tools to characterize receptor subtypes.

  4. Important roles of P2Y receptors in the inflammation and cancer of digestive system.

    Science.gov (United States)

    Wan, Han-Xing; Hu, Jian-Hong; Xie, Rei; Yang, Shi-Ming; Dong, Hui

    2016-05-10

    Purinergic signaling is important for many biological processes in humans. Purinoceptors P2Y are widely distributed in human digestive system and different subtypes of P2Y receptors mediate different physiological functions from metabolism, proliferation, differentiation to apoptosis etc. The P2Y receptors are essential in many gastrointestinal functions and also involve in the occurrence of some digestive diseases. Since different subtypes of P2Y receptors are present on the same cell of digestive organs, varying subtypes of P2Y receptors may have opposite or synergetic functions on the same cell. Recently, growing lines of evidence strongly suggest the involvement of P2Y receptors in the pathogenesis of several digestive diseases. In this review, we will focus on their important roles in the development of digestive inflammation and cancer. We anticipate that as the special subtypes of P2Y receptors are studied in depth, specific modulators for them will have good potentials to become promising new drugs to treat human digestive diseases in the near future.

  5. Activation of lysosomal P2X4 by ATP transported into lysosomes via VNUT/SLC17A9 using V‐ATPase generated voltage gradient as the driving force

    Science.gov (United States)

    Zhong, Xi Zoë; Cao, Qi; Sun, Xue

    2016-01-01

    Key points SLC17A9 proteins function as a lysosomal ATP transporter responsible for lysosomal ATP accumulation.P2X4 receptors act as lysosomal ion channels activated by luminal ATP.SLC17A9‐mediated ATP transport across the lysosomal membrane is suppressed by Bafilomycin A1, the V‐ATPase inhibitor.SLC17A9 mainly uses voltage gradient but not pH gradient generated by the V‐ATPase as the driving force to transport ATP into the lysosome to activate P2X4. Abstract The lysosome contains abundant ATP which plays important roles in lysosome functions and in cell signalling. Recently, solute carrier family 17 member 9 (SLC17A9, also known as VNUT for vesicular nucleotide transporter) proteins were suggested to function as a lysosomal ATP transporter responsible for lysosomal ATP accumulation, and P2X4 receptors were suggested to be lysosomal ion channels that are activated by luminal ATP. However, the molecular mechanism of SLC17A9 transporting ATP and the regulatory mechanism of lysosomal P2X4 are largely unknown. In this study, we report that SLC17A9‐mediated ATP transport across lysosomal membranes is suppressed by Bafilomycin A1, the V‐ATPase inhibitor. By measuring P2X4 activity, which is indicative of ATP transport across lysosomal membranes, we further demonstrated that SLC17A9 mainly uses voltage gradient but not pH gradient as the driving force to transport ATP into lysosomes. This study provides a molecular mechanism for lysosomal ATP transport mediated by SLC17A9. It also suggests a regulatory mechanism of lysosomal P2X4 by SLC17A9. PMID:27477609

  6. Deficiency of the Purinergic Receptor 2X7 Attenuates Nonalcoholic Steatohepatitis Induced by High-Fat Diet: Possible Role of the NLRP3 Inflammasome

    Directory of Open Access Journals (Sweden)

    Claudia Blasetti Fantauzzi

    2017-01-01

    Full Text Available Molecular mechanisms driving transition from simple steatosis to nonalcoholic steatohepatitis (NASH, a critical step in the progression of nonalcoholic fatty liver disease (NAFLD to cirrhosis, are poorly defined. This study aimed at investigating the role of the purinergic receptor 2X7 (PR2X7, through the NLRP3 inflammasome, in the development of NASH. To this end, mice knockout for the Pr2x7 gene (Pr2x7−/− and coeval wild-type (WT mice were fed a high-fat diet (HFD or normal-fat diet for 16 weeks. NAFLD grade and stage were lower in Pr2x7−/− than WT mice, and only 1/7 Pr2x7−/− animals showed evidence of NASH, as compared with 4/7 WT mice. Molecular markers of inflammation, oxidative stress, and fibrosis were markedly increased in WT-HFD mice, whereas no or significantly reduced increments were detected in Pr2x7−/− animals, which showed also decreased modulation of genes of lipid metabolism. Deletion of Pr2x7 gene was associated with blunted or abolished activation of NLRP3 inflammasome and expression of its components, which were induced in liver sinusoidal endothelial cells challenged with appropriate stimuli. These data show that Pr2x7 gene deletion protects mice from HFD-induced NASH, possibly through blunted activation of NLRP3 inflammasome, suggesting that PR2X7 and NLRP3 may represent novel therapeutic targets.

  7. Role of the Ectodomain Serine 275 in Shaping the Binding Pocket of the ATP-Gated P2X3 Receptor

    Czech Academy of Sciences Publication Activity Database

    Petrenko, N.; Khafizov, K.; Tvrdoňová, Vendula; Skorinkin, A.; Giniatullin, R.

    2011-01-01

    Roč. 50, č. 39 (2011), s. 8427-8436 ISSN 0006-2960 Grant - others:Univerzita Karlova(CZ) 3446/2011 Institutional research plan: CEZ:AV0Z50110509 Keywords : P2X3 * purinergic * ATP * ATP-binding pocket * receptor Subject RIV: ED - Physiology Impact factor: 3.422, year: 2011

  8. ATP is stored in lamellar bodies to activate vesicular P2X4 in an autocrine fashion upon exocytosis.

    Science.gov (United States)

    Fois, Giorgio; Winkelmann, Veronika Eva; Bareis, Lara; Staudenmaier, Laura; Hecht, Elena; Ziller, Charlotte; Ehinger, Konstantin; Schymeinsky, Jürgen; Kranz, Christine; Frick, Manfred

    2018-02-05

    Vesicular P2X 4 receptors are known to facilitate secretion and activation of pulmonary surfactant in the alveoli of the lungs. P2X 4 receptors are expressed in the membrane of lamellar bodies (LBs), large secretory lysosomes that store lung surfactant in alveolar type II epithelial cells, and become inserted into the plasma membrane after exocytosis. Subsequent activation of P2X 4 receptors by adenosine triphosphate (ATP) results in local fusion-activated cation entry (FACE), facilitating fusion pore dilation, surfactant secretion, and surfactant activation. Despite the importance of ATP in the alveoli, and hence lung function, the origin of ATP in the alveoli is still elusive. In this study, we demonstrate that ATP is stored within LBs themselves at a concentration of ∼1.9 mM. ATP is loaded into LBs by the vesicular nucleotide transporter but does not activate P2X 4 receptors because of the low intraluminal pH (5.5). However, the rise in intravesicular pH after opening of the exocytic fusion pore results in immediate activation of vesicular P2X 4 by vesicular ATP. Our data suggest a new model in which agonist (ATP) and receptor (P2X 4 ) are located in the same intracellular compartment (LB), protected from premature degradation (ATP) and activation (P2X 4 ), and ideally placed to ensure coordinated and timely receptor activation as soon as fusion occurs to facilitate surfactant secretion. © 2018 Fois et al.

  9. PPADS: an antagonist at endothelial P2Y-purinoceptors but not P2U-purinoceptors.

    Science.gov (United States)

    Brown, C; Tanna, B; Boarder, M R

    1995-11-01

    1. Bovine aortic endothelial (BAE) cells contain two co-existing receptors for extracellular ATP, the P2Y and P2U-purinoceptors. Here we have determined whether the proposed P2X-purinoceptor antagonist, pyridoxalphosphate-6-azophenyl-2', 4'-disulphonic acid (PPADS) could distinguish between these two receptor subtypes. 2. Cells labelled with myo-[2-3H]-inositol were stimulated with increasing concentrations of either the P2Y-agonist, 2MeSATP, or the P2U-agonist, UTP in the absence or presence of 30 microM PPADS. The accumulation of total [3H]-inositol (poly)phosphates mediated by 2MeSATP was markedly attenuated by PPADS, whereas the response to UTP was not significantly affected. 3. Stimulation of BAE cells with increasing concentrations of ATP showed a reduced response in the presence of 10 microM PPADS, but this effect of the antagonist was not significant. By contrast, inhibition of the response to ADP was profound and highly significant. 4. These observations show that PPADS is not a selective P2X-purinoceptor antagonist, but is able to distinguish between P2Y- and P2YU-purinoceptors in BAE cells, and indicate that this compound may provide a useful tool in the study of multiple subtypes of P2-purinoceptors. Furthermore the results are consistent with the hypothesis that ATP interacts with both receptor subtypes, but that the action of ADP is primarily at the P2Y-purinoceptor in these endothelial cells.

  10. Communication between corneal epithelial cells and trigeminal neurons is facilitated by purinergic (P2) and glutamatergic receptors.

    Science.gov (United States)

    Oswald, Duane J; Lee, Albert; Trinidad, Monique; Chi, Cheryl; Ren, Ruiyi; Rich, Celeste B; Trinkaus-Randall, Vickery

    2012-01-01

    Previously, we demonstrated that nucleotides released upon mechanical injury to corneal epithelium activate purinergic (P2) receptors resulting in mobilization of a Ca(2+) wave. However, the tissue is extensively innervated and communication between epithelium and neurons is critical and not well understood. Therefore, we developed a co-culture of primary trigeminal neurons and human corneal limbal epithelial cells. We demonstrated that trigeminal neurons expressed a repertoire of P2Yand P2X receptor transcripts and responded to P2 agonists in a concentration-dependent manner. Mechanical injuries to epithelia in the co-cultures elicited a Ca(2+) wave that mobilized to neurons and was attenuated by Apyrase, an ectonucleotidase. To elucidate the role of factors released from each cell type, epithelial and neuronal cells were cultured, injured, and the wound media from one cell type was collected and added to the other cell type. Epithelial wound media generated a rapid Ca(2+) mobilization in neuronal cells that was abrogated in the presence of Apyrase, while neuronal wound media elicited a complex response in epithelial cells. The rapid Ca(2+) mobilization was detected, which was abrogated with Apyrase, but it was followed by Ca(2+) waves that occurred in cell clusters. When neuronal wound media was preincubated with a cocktail of N-methyl-D-aspartate (NMDA) receptor inhibitors, the secondary response in epithelia was diminished. Glutamate was detected in the neuronal wound media and epithelial expression of NMDA receptor subunit transcripts was demonstrated. Our results indicate that corneal epithelia and neurons communicate via purinergic and NMDA receptors that mediate the wound response in a highly orchestrated manner.

  11. Communication between corneal epithelial cells and trigeminal neurons is facilitated by purinergic (P2 and glutamatergic receptors.

    Directory of Open Access Journals (Sweden)

    Duane J Oswald

    Full Text Available Previously, we demonstrated that nucleotides released upon mechanical injury to corneal epithelium activate purinergic (P2 receptors resulting in mobilization of a Ca(2+ wave. However, the tissue is extensively innervated and communication between epithelium and neurons is critical and not well understood. Therefore, we developed a co-culture of primary trigeminal neurons and human corneal limbal epithelial cells. We demonstrated that trigeminal neurons expressed a repertoire of P2Yand P2X receptor transcripts and responded to P2 agonists in a concentration-dependent manner. Mechanical injuries to epithelia in the co-cultures elicited a Ca(2+ wave that mobilized to neurons and was attenuated by Apyrase, an ectonucleotidase. To elucidate the role of factors released from each cell type, epithelial and neuronal cells were cultured, injured, and the wound media from one cell type was collected and added to the other cell type. Epithelial wound media generated a rapid Ca(2+ mobilization in neuronal cells that was abrogated in the presence of Apyrase, while neuronal wound media elicited a complex response in epithelial cells. The rapid Ca(2+ mobilization was detected, which was abrogated with Apyrase, but it was followed by Ca(2+ waves that occurred in cell clusters. When neuronal wound media was preincubated with a cocktail of N-methyl-D-aspartate (NMDA receptor inhibitors, the secondary response in epithelia was diminished. Glutamate was detected in the neuronal wound media and epithelial expression of NMDA receptor subunit transcripts was demonstrated. Our results indicate that corneal epithelia and neurons communicate via purinergic and NMDA receptors that mediate the wound response in a highly orchestrated manner.

  12. Depression of NMDA receptor-mediated synaptic transmission by four α2 adrenoceptor agonists on the in vitro rat spinal cord preparation

    Science.gov (United States)

    Faber, E S L; Chambers, J P; Evans, R H

    1998-01-01

    α2-Adrenoceptor agonists have a spinal site of analgesic action. In the current study the synaptic depressant actions of xylazine, detomidine, romifidine and dexmedetomidine have been compared on segmental reflexes containing NMDA receptor-mediated components in the neonatal rat hemisected spinal cord preparation in vitro.Reflexes were evoked in the ventral root following either supramaximal electrical stimulation of the corresponding ipsilateral lumbar dorsal root to evoke the high intensity excitatory postsynaptic potential (e.p.s.p.) involving all primary afferent fibres, or low intensity stimulation to evoke the solely A fibre-mediated low intensity e.p.s.p. The high intensity e.p.s.p. contains a greater NMDA receptor-mediated component.Xylazine, romifidine, detomidine and dexmedetomidine all depressed both the high intensity e.p.s.p. and the low intensity e.p.s.p. giving respective EC50 values of 0.91±0.2 μM (n=12), 23.4±3 nM (n=12), 37.7±7 nM (n=8) and 0.84±0.1 nM (n=4) for depression of the high intensity e.p.s.p. and 0.76±0.1 μM (n=12), 22.0±3 nM (n=12), 24.9±6 nM (n=4) and 2.7±0.6 nM (n=4) for depression of the low intensity e.p.s.p., respectively. Unlike the other three drugs, the two values for dexmedetomidine, showing a greater selectivity for the high intensity e.p.s.p., are significantly different.Each of these depressant actions was reversed by the selective α2-adrenoceptor antagonist atipamezole (1 μM).In contrast to previous reports of the actions of α2-adrenoceptor agonists on the in vitro spinal cord preparation, at concentrations ten fold higher than the above EC50 values xylazine, romifidine, detomidine and dexmedetomidine depressed the initial population spike of motoneurons (MSR). This depression was not reversed by atipamezole.Comparison of the rank order of the present EC50 values for depression of the high intensity e.p.s.p. with potency ratios from in vivo analgesic tests in previous studies show a close

  13. CDK11p58 represses vitamin D receptor-mediated transcriptional activation through promoting its ubiquitin-proteasome degradation

    International Nuclear Information System (INIS)

    Chi, Yayun; Hong, Yi; Zong, Hongliang; Wang, Yanlin; Zou, Weiying; Yang, Junwu; Kong, Xiangfei; Yun, Xiaojing; Gu, Jianxin

    2009-01-01

    Vitamin D receptor (VDR) is a member of the nuclear receptor superfamily and regulates transcription of target genes. In this study, we identified CDK11 p58 as a novel protein involved in the regulation of VDR. CDK11 p58 , a member of the large family of p34cdc2-related kinases, is associated with cell cycle progression, tumorigenesis, and apoptotic signaling. Our study demonstrated that CDK11 p58 interacted with VDR and repressed VDR-dependent transcriptional activation. Furthermore, overexpression of CDK11 p58 decreased the stability of VDR through promoting its ubiquitin-proteasome-mediated degradation. Taken together, these results suggest that CDK11 p58 is involved in the negative regulation of VDR.

  14. Deciphering the regulation of P2X4 receptor channel gating by ivermectin using Markov models

    Czech Academy of Sciences Publication Activity Database

    Mackay, L.; Zemková, Hana; Stojilkovic, S. S.; Sherman, A.; Khadra, A.

    2017-01-01

    Roč. 13, č. 7 (2017), č. článku e1005643. ISSN 1553-734X R&D Projects: GA ČR(CZ) GBP304/12/G069 Institutional support: RVO:67985823 Keywords : Markov models * ion channel gating * sensory receptors * cation s Subject RIV: ED - Physiology OBOR OECD: Physiology (including cytology) Impact factor: 4.542, year: 2016

  15. Cerebellar Kainate Receptor-Mediated Facilitation of Glutamate Release Requires Ca2+-Calmodulin and PKA

    Directory of Open Access Journals (Sweden)

    Rafael Falcón-Moya

    2018-06-01

    Full Text Available We elucidated the mechanisms underlying the kainate receptor (KAR-mediated facilitatory modulation of synaptic transmission in the cerebellum. In cerebellar slices, KA (3 μM increased the amplitude of evoked excitatory postsynaptic currents (eEPSCs at synapses between axon terminals of parallel fibers (PF and Purkinje neurons. KA-mediated facilitation was antagonized by NBQX under condition where AMPA receptors were previously antagonized. Inhibition of protein kinase A (PKA suppressed the effect of KA on glutamate release, which was also obviated by the prior stimulation of adenylyl cyclase (AC. KAR-mediated facilitation of synaptic transmission was prevented by blocking Ca2+ permeant KARs using philanthotoxin. Furthermore, depletion of intracellular Ca2+ stores by thapsigargin, or inhibition of Ca2+-induced Ca2+-release by ryanodine, abrogated the synaptic facilitation by KA. Thus, the KA-mediated modulation was conditional on extracellular Ca2+ entry through Ca2+-permeable KARs, as well as and mobilization of Ca2+ from intracellular stores. Finally, KAR-mediated facilitation was sensitive to calmodulin inhibitors, W-7 and calmidazolium, indicating that the increased cytosolic [Ca2+] sustaining KAR-mediated facilitation of synaptic transmission operates through a downstream Ca2+/calmodulin coupling. We conclude that, at cerebellar parallel fiber-Purkinje cell synapses, presynaptic KARs mediate glutamate release facilitation, and thereby enhance synaptic transmission through Ca2+-calmodulin dependent activation of adenylyl cyclase/cAMP/protein kinase A signaling.

  16. The p38 mitogen activated protein kinase regulates β-amyloid protein internalization through the α7 nicotinic acetylcholine receptor in mouse brain.

    Science.gov (United States)

    Ma, Kai-Ge; Lv, Jia; Yang, Wei-Na; Chang, Ke-Wei; Hu, Xiao-Dan; Shi, Li-Li; Zhai, Wan-Ying; Zong, Hang-Fan; Qian, Yi-Hua

    2018-03-01

    Alzheimer's disease (AD) is one of the most devastating neurodegenerative disorders. Intracellular β-amyloid protein (Aβ) is an early event in AD. It induces the formation of amyloid plaques and neuron damage. The α7 nicotinic acetylcholine receptor7nAChR) has been suggested to play an important role in Aβ caused cognition. It has high affinity with Aβ and could mediate Aβ internalization in vitro. However, whether in mouse brain the p38 MAPK signaling pathway is involved in the regulation of the α7nAChR mediated Aβ internalization and their role in mitochondria remains little known. Therefore, in this study, we revealed that Aβ is internalized by cholinergic and GABAergic neurons. The internalized Aβ were found deposits in lysosomes/endosomes and mitochondria. Aβ could form Aβ-α7nAChR complex with α7nAChR, activates the p38 mitogen activated protein kinase (MAPK). And the increasing of α7nAChR could in return mediate Aβ internalization in the cortex and hippocampus. In addition, by using the α7nAChR agonist PNU282987, the p38 phosphorylation level decreases, rescues the biochemical changes which are tightly associated with Aβ-induced apoptosis, such as Bcl2/Bax level, cytochrome c (Cyt c) release. Collectively, the p38 MAPK signaling pathway could regulate the α7nAChR-mediated internalization of Aβ. The activation of α7nAChR or the inhibition of p38 MAPK signaling pathway may be a beneficial therapy to AD. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Functional expression of P2 purinoceptors in a primary neuroglial cell culture of the rat arcuate nucleus.

    Science.gov (United States)

    Pollatzek, Eric; Hitzel, Norma; Ott, Daniela; Raisl, Katrin; Reuter, Bärbel; Gerstberger, Rüdiger

    2016-07-07

    The arcuate nucleus (ARC) plays an important role in the hypothalamic control of energy homeostasis. Expression of various purinoceptor subtypes in the rat ARC and physiological studies suggest a modulatory function of P2 receptors within the neuroglial ARC circuitry. A differentiated mixed neuronal and glial microculture was therefore established from postnatal rat ARC, revealing neuronal expression of ARC-specific transmitters involved in food intake regulation (neuropeptide Y (NPY), proopiomelanocortin (POMC), tyrosine hydroxylase (TH)). Some NPYergic neurons cosynthesized TH, while POMC and TH expression proved to be mutually exclusive. Stimulation with the general purinoceptor agonists 2-methylthioadenosine-5'triphosphate (2-MeSATP) and ATP but not the P2X1/P2X3 receptor subtype agonist α,β-methyleneadenosine-5'triphosphate (α,β-meATP) induced intracellular calcium signals in ARC neurons and astrocytes. Some 5-10% each of 2-MeSATP responsive neurons expressed POMC, NYP or TH. Supporting the calcium imaging data, radioligand binding studies to hypothalamic membranes showed high affinity for 2-MeSATP, ATP but not α,β-meATP to displace [α-(35)S]deoxyadenosine-5'thiotriphosphate ([(35)S]dATPαS) from P2 receptors. Repetitive superfusion with equimolar 2-MeSATP allowed categorization of ARC cells into groups with a high or low (LDD) degree of purinoceptor desensitization, the latter allowing further receptor characterization. Calcium imaging experiments performed at 37°C vs. room temperature showed further reduction of desensitization. Agonist-mediated intracellular calcium signals were suppressed in all LDD neurons but only 25% of astrocytes in the absence of extracellular calcium, suggestive of metabotropic P2Y receptor expression in the majority of ARC astrocytes. The highly P2Y1-selective receptor agonists MRS2365 and 2-methylthioadenosine-5'diphosphate (2-MeSADP) activated 75-85% of all 2-MeSATP-responsive ARC astrocytes. Taking into consideration the

  18. Selective coupling of the S1P3 receptor subtype to S1P-mediated RhoA activation and cardioprotection.

    Science.gov (United States)

    Yung, Bryan S; Brand, Cameron S; Xiang, Sunny Y; Gray, Charles B B; Means, Christopher K; Rosen, Hugh; Chun, Jerold; Purcell, Nicole H; Brown, Joan Heller; Miyamoto, Shigeki

    2017-02-01

    Sphingosine-1-phosphate (S1P), a bioactive lysophospholipid, is generated and released at sites of tissue injury in the heart and can act on S1P 1 , S1P 2 , and S1P 3 receptor subtypes to affect cardiovascular responses. We established that S1P causes little phosphoinositide hydrolysis and does not induce hypertrophy indicating that it does not cause receptor coupling to G q . We previously demonstrated that S1P confers cardioprotection against ischemia/reperfusion by activating RhoA and its downstream effector PKD. The S1P receptor subtypes and G proteins that regulate RhoA activation and downstream responses in the heart have not been determined. Using siRNA or pertussis toxin to inhibit different G proteins in NRVMs we established that S1P regulates RhoA activation through Gα 13 but not Gα 12 , Gα q , or Gα i . Knockdown of the three major S1P receptors using siRNA demonstrated a requirement for S1P 3 in RhoA activation and subsequent phosphorylation of PKD, and this was confirmed in studies using isolated hearts from S1P 3 knockout (KO) mice. S1P treatment reduced infarct size induced by ischemia/reperfusion in Langendorff perfused wild-type (WT) hearts and this protection was abolished in the S1P 3 KO mouse heart. CYM-51736, an S1P 3 -specific agonist, also decreased infarct size after ischemia/reperfusion to a degree similar to that achieved by S1P. The finding that S1P 3 receptor- and Gα 13 -mediated RhoA activation is responsible for protection against ischemia/reperfusion suggests that selective targeting of S1P 3 receptors could provide therapeutic benefits in ischemic heart disease. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Transformation of Astrocytes to a Neuroprotective Phenotype by Microglia via P2Y1 Receptor Downregulation

    Directory of Open Access Journals (Sweden)

    Youichi Shinozaki

    2017-05-01

    Full Text Available Microglia and astrocytes become reactive following traumatic brain injury (TBI. However, the coordination of this reactivity and its relation to pathophysiology are unclear. Here, we show that microglia transform astrocytes into a neuroprotective phenotype via downregulation of the P2Y1 purinergic receptor. TBI initially caused microglial activation in the injury core, followed by reactive astrogliosis in the peri-injured region and formation of a neuroprotective astrocyte scar. Equivalent changes to astrocytes were observed in vitro after injury. This change in astrocyte phenotype resulted from P2Y1 receptor downregulation, mediated by microglia-derived cytokines. In mice, astrocyte-specific P2Y1 receptor overexpression (Astro-P2Y1OE counteracted scar formation, while astrocyte-specific P2Y1 receptor knockdown (Astro-P2Y1KD facilitated scar formation, suggesting critical roles of P2Y1 receptors in the transformation. Astro-P2Y1OE and Astro-P2Y1KD mice showed increased and reduced neuronal damage, respectively. Altogether, our findings indicate that microglia-astrocyte interaction, involving a purinergic signal, is essential for the formation of neuroprotective astrocytes.

  20. Inhibition of Toll-like receptor 2-mediated interleukin-8 production in Cystic Fibrosis airway epithelial cells via the alpha7-nicotinic acetylcholine receptor.

    LENUS (Irish Health Repository)

    Greene, Catherine M

    2010-01-01

    Cystic Fibrosis (CF) is an inherited disorder characterised by chronic inflammation of the airways. The lung manifestations of CF include colonization with Pseudomonas aeruginosa and Staphylococcus aureus leading to neutrophil-dominated airway inflammation and tissue damage. Inflammation in the CF lung is initiated by microbial components which activate the innate immune response via Toll-like receptors (TLRs), increasing airway epithelial cell production of proinflammatory mediators such as the neutrophil chemokine interleukin-8 (IL-8). Thus modulation of TLR function represents a therapeutic approach for CF. Nicotine is a naturally occurring plant alkaloid. Although it is negatively associated with cigarette smoking and cardiovascular damage, nicotine also has anti-inflammatory properties. Here we investigate the inhibitory capacity of nicotine against TLR2- and TLR4-induced IL-8 production by CFTE29o- airway epithelial cells, determine the role of alpha7-nAChR (nicotinic acetylcholine receptor) in these events, and provide data to support the potential use of safe nicotine analogues as anti-inflammatories for CF.

  1. The ACE-2/Ang1-7/Mas cascade enhances bone structure and metabolism following angiotensin-II type 1 receptor blockade.

    Science.gov (United States)

    Abuohashish, Hatem M; Ahmed, Mohammed M; Sabry, Dina; Khattab, Mahmoud M; Al-Rejaie, Salim S

    2017-07-15

    The renin angiotensin system (RAS) regulates numerous systemic functions and is expressed locally in skeletal tissues. Angiotensin1-7 (Ang1-7) is a beneficial member of the RAS, and the therapeutic effects of a large number of angiotensin receptors blockers (ARBs) are mediated by an Ang1-7-dependent cascade. This study examines whether the reported osteo-preservative effects of losartan are mediated through the angiotensin converting enzyme2 (ACE-2)/Ang1-7/Mas pathway in ovariectomized (OVX) rats. Sham and OVX animals received losartan (10mg/kg/d p.o.) for 6 weeks. A specific Mas receptor blocker (A-779) was delivered via mini-osmotic pumps during the losartan treatment period. Serum and urine bone metabolism biomarker levels were measured. Bone trabecular and cortical morphometry were quantified in distal femurs, whereas mineral contents were estimated in ashed bones, serum and urine. Finally, the expression of RAS components, the receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) was determined. Losartan significantly improved the elevated bone metabolism marker levels and altered trabecular and cortical structures in OVX animals, and restored normal urinary and skeletal mineral levels. Mas receptor inhibition significantly abolished all osteo-protective effects of losartan and enhanced the deleterious effects of OVX. Losartan enhanced OVX-induced up-regulation of ACE-1, AngII, angiotensin type 1 (AT 1 ) receptor and RANKL expression, and increased ACE-2, Ang1-7, Mas and OPG expression in OVX animals. However, A-779 significantly eradicated the effects of losartan on RAS components and RANKL/OPG expression. Thus, Ang1-7 are involved in the osteo-preservative effects of losartan via Mas receptor, which may add therapeutic value to this well-known antihypertensive agent. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Effects of X-rays on CC-chemokine receptor 7 expression in human lung cancer A549 cells

    International Nuclear Information System (INIS)

    Wang Cuilan; Jiang Qisheng; Zou Yue; Li Fengsheng; Li Wei; Song Xiujun; He Rui; Wang Lu

    2011-01-01

    Objective: To study the effects of X-ray radiation on CC-chemokine receptor 7 (CCR7) expression in human non-small cell lung cancer (NSCLC) cells. Methods: Human adenocarcinoma cells of the line A549 were cultured and irradiated by X-ray at the absorbed doses of 2, 4, 6, and 8 Gy respectively by linear accelerator (with the source skin distance of 100 cm and dose rate of 442.89 cGy/min). The relative levels of CCR7 mRNA and protein expression in the A549 cells were respectively detected by real time-PCR and Western blotting 4, 12, 24, 48, and 72 h after radiation.Untreated A549 cells were used as control group. Results: The expression levels of CCR7 mRNA and protein in the A549 cells began to increase since 4 h after radiation and then decreased gradually after they reached the peak. The CCR7 mRNA expression levels 72 h after radiation of the 6 and 8 Gy groups were still significantly higher than those of the control group (t=6.75-7.26, both P<0.01), and the CCR7 protein expression levels of the 2 and 6 Gy group were still significantly higher than those of the control group (t=11.13-14.17, both P<0.01). Then the CCR7 protein expression levels of the 4 and 8 Gy groups decreased to the control group level 48 and 72 h after radiation respectively. Conclusions: The CCR7 mRNA and protein expression levels in the NSCLC cells increase after X-ray irradiation,which may be correlated with the promotion of proliferation and metastasis of NSCLC cells by X-ray irradiation at a certain dose. (authors)

  3. Berberine reduces fibronectin expression by suppressing the S1P-S1P2 receptor pathway in experimental diabetic nephropathy models.

    Directory of Open Access Journals (Sweden)

    Kaipeng Huang

    Full Text Available The accumulation of glomerular extracellular matrix (ECM is one of the critical pathological characteristics of diabetic renal fibrosis. Fibronectin (FN is an important constituent of ECM. Our previous studies indicate that the activation of the sphingosine kinase 1 (SphK1-sphingosine 1- phosphate (S1P signaling pathway plays a key regulatory role in FN production in glomerular mesangial cells (GMCs under diabetic condition. Among the five S1P receptors, the activation of S1P2 receptor is the most abundant. Berberine (BBR treatment also effectively inhibits SphK1 activity and S1P production in the kidneys of diabetic models, thus improving renal injury. Based on these data, we further explored whether BBR could prevent FN production in GMCs under diabetic condition via the S1P2 receptor. Here, we showed that BBR significantly down-regulated the expression of S1P2 receptor in diabetic rat kidneys and GMCs exposed to high glucose (HG and simultaneously inhibited S1P2 receptor-mediated FN overproduction. Further, BBR also obviously suppressed the activation of NF-κB induced by HG, which was accompanied by reduced S1P2 receptor and FN expression. Taken together, our findings suggest that BBR reduces FN expression by acting on the S1P2 receptor in the mesangium under diabetic condition. The role of BBR in S1P2 receptor expression regulation could closely associate with its inhibitory effect on NF-κB activation.

  4. Preparation and structural properties of nonlinear optical borates K{sub 2(1-x)}Rb{sub 2x}Al{sub 2}B{sub 2}O{sub 7}, 0 < x < 0.75

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, V.V., E-mail: atuchin@thermo.isp.nsc.ru [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Bazarov, B.G. [Laboratory of Oxide Systems, Baikal Institute of Nature Management, SB RAS, Ulan-Ude 47, 670047 (Russian Federation); Gavrilova, T.A. [Laboratory of Nanodiagnostics and Nanolithography, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation); Grossman, V.G. [Laboratory of Oxide Systems, Baikal Institute of Nature Management, SB RAS, Ulan-Ude 47, 670047 (Russian Federation); Molokeev, M.S. [Laboratory of Crystal Physics, Institute of Physics, SB RAS, Krasnoyarsk 660036 (Russian Federation); Bazarova, Zh.G. [Laboratory of Oxide Systems, Baikal Institute of Nature Management, SB RAS, Ulan-Ude 47, 670047 (Russian Federation)

    2012-02-25

    Highlights: Black-Right-Pointing-Pointer Solid solutions K{sub 2(1-x)}Rb{sub 2x}Al{sub 2}B{sub 2}O{sub 7} are synthesized over wide composition range up to x {approx} 0.83. Black-Right-Pointing-Pointer Crystal structure of K{sub 2(1-x)}Rb{sub 2x}Al{sub 2}B{sub 2}O{sub 7} solutions is determined in space group P321. Black-Right-Pointing-Pointer Second harmonic generation is observed in KRbAl{sub 2}B{sub 2}O{sub 7}. Black-Right-Pointing-Pointer Drastic variation of cell parameters is found over KABO-type crystal family. - Abstract: The structures of K{sub 2(1-x)}Rb{sub 2x}Al{sub 2}B{sub 2}O{sub 7}, x = 0.25, 0.5, 0.75, have been determined in space group P321 through Rietveld analysis of X-ray powder diffraction data. The solubility limit in K{sub 2(1-x)}Rb{sub 2x}Al{sub 2}B{sub 2}O{sub 7} crystals has been estimated as x {approx} 0.83-0.9. Nonlinear optical properties of KRbAl{sub 2}B{sub 2}O{sub 7} have been verified by powder Kurtz-Perry method. Mechanisms of structural parameter variation in K{sub 2}Al{sub 2}B{sub 2}O{sub 7} crystal family have been discussed.

  5. Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on estrogenic responses

    Energy Technology Data Exchange (ETDEWEB)

    Romkes, M.

    1988-01-01

    The competitive receptor binding affinities of thirteen 2-substituted-3,7,8-trichlorodibenzo-p-dioxins to hepatic cytosol from rat, mouse, guinea pig and hamster were determined using ({sup 3}H)-2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) as the radio-ligand. Significant species-dependent structural differences in the Ah receptor ligand binding site were observed and support the heterologous nature of the receptor protein. The interactions of 2,3,7,8-TCDD and estrogenic responses in the female rat and human breast cancer cells were also investigated. Cotreatment of 25-day-old female Long Evans rats with 20 or 80 ug/kg of 2,3,7,8-TCDD resulted in a dose-dependent decrease in both uterine and hepatic estrogen receptor (ER) levels. Moreover, these levels are decreased for at least ten days and appear to be related to the tissue persistence of 2,3,7,8-TCDD. In contrast, estradiol elevated uterine and hepatic ER levels and increased uterine wet weights. Cotreatment of the rats with 2,3,7,8-TCDD and estradiol resulted in hepatic and uterine ER levels which were comparable to those observed in the control rats; in addition, 2,3,7,8-TCDD also antagonized the effects of estradiol-induced uterine wet weights.

  6. Stimulatory Effects of Melatonin on Porcine In Vitro Maturation Are Mediated by MT2 Receptor

    Directory of Open Access Journals (Sweden)

    Sanghoon Lee

    2018-05-01

    Full Text Available Melatonin is a multifunctional molecule with numerous biological activities. The fact that melatonin modulates the functions of porcine granulosa cells via the MT2 receptor suggests the possibility of MT2 receptor-mediation for melatonin to promote cumulus expansion of porcine cumulus-oocyte complexes (COCs. Therefore, we investigated the presence of MT2 in porcine COCs, and the effects of melatonin with or without selective MT2 antagonists (luzindole and 4-P-PDOT on this process; COCs underwent in vitro maturation culturing with six different conditions (control, melatonin, luzindole, 4-P-PDOT, melatonin + luzindole or melatonin + 4-P-PDOT. Cumulus expansion, oocyte nuclear maturation, and subsequent embryo development after parthenogenetic activation (PA were evaluated. In experiment 1, MT2 was expressed in both oocytes and cumulus cells. In experiment 2, melatonin significantly increased the proportion of complete cumulus expansion (degree 4, which was inhibited by simultaneous addition of either luzindole or 4-P-PDOT. A similar pattern was observed in the expression of genes related to cumulus expansion, apoptosis, and MT2. In experiment 3, no significant difference was observed in immature, degenerate, and MII oocyte rates among the groups. In experiment 4, melatonin significantly increased blastocyst formation rates and total blastocyst cell numbers after PA, but these effects were abolished when either luzindole or 4-P-PDOT was added concomitantly. In conclusion, our results indicate that the MT2 receptor mediated the stimulatory effects of melatonin on porcine cumulus expansion and subsequent embryo development.

  7. {delta}-Opioid receptor-stimulated Akt signaling in neuroblastoma x glioma (NG108-15) hybrid cells involves receptor tyrosine kinase-mediated PI3K activation

    Energy Technology Data Exchange (ETDEWEB)

    Heiss, Anika; Ammer, Hermann [Institute of Pharmacology, Toxicology and Pharmacy Ludwig-Maximilians-University of Munich Koeniginstrasse 16 80539 Muenchen Federal Republic of Germany (Germany); Eisinger, Daniela A., E-mail: eisinger@pharmtox.vetmed.uni-muenchen.de [Institute of Pharmacology, Toxicology and Pharmacy Ludwig-Maximilians-University of Munich Koeniginstrasse 16 80539 Muenchen Federal Republic of Germany (Germany)

    2009-07-15

    {delta}-Opioid receptor (DOR) agonists possess cytoprotective properties, an effect associated with activation of the 'pro-survival' kinase Akt. Here we delineate the signal transduction pathway by which opioids induce Akt activation in neuroblastoma x glioma (NG108-15) hybrid cells. Exposure of the cells to both [D-Pen{sup 2,5}]enkephalin and etorphine resulted in a time- and dose-dependent increase in Akt activity, as measured by means of an activation-specific antibody recognizing phosphoserine-473. DOR-mediated Akt signaling is blocked by the opioid antagonist naloxone and involves inhibitory G{sub i/o} proteins, because pre-treatment with pertussis toxin, but not over-expression of the G{sub q/11} scavengers EBP50 and GRK2-K220R, prevented this effect. Further studies with Wortmannin and LY294002 revealed that phophoinositol-3-kinase (PI3K) plays a central role in opioid-induced Akt activation. Opioids stimulate Akt activity through transactivation of receptor tyrosine kinases (RTK), because pre-treatment of the cells with inhibitors for neurotrophin receptor tyrosine kinases (AG879) and the insulin-like growth factor receptor IGF-1 (AG1024), but not over-expression of the G{beta}{gamma} scavenger phosducin, abolished this effect. Activated Akt translocates to the nuclear membrane, where it promotes GSK3 phosphorylation and prevents caspase-3 cleavage, two key events mediating inhibition of cell apoptosis and enhancement of cell survival. Taken together, these results demonstrate that in NG108-15 hybrid cells DOR agonists possess cytoprotective properties mediated by activation of the RTK/PI3K/Akt signaling pathway.

  8. δ-Opioid receptor-stimulated Akt signaling in neuroblastoma x glioma (NG108-15) hybrid cells involves receptor tyrosine kinase-mediated PI3K activation

    International Nuclear Information System (INIS)

    Heiss, Anika; Ammer, Hermann; Eisinger, Daniela A.

    2009-01-01

    δ-Opioid receptor (DOR) agonists possess cytoprotective properties, an effect associated with activation of the 'pro-survival' kinase Akt. Here we delineate the signal transduction pathway by which opioids induce Akt activation in neuroblastoma x glioma (NG108-15) hybrid cells. Exposure of the cells to both [D-Pen 2,5 ]enkephalin and etorphine resulted in a time- and dose-dependent increase in Akt activity, as measured by means of an activation-specific antibody recognizing phosphoserine-473. DOR-mediated Akt signaling is blocked by the opioid antagonist naloxone and involves inhibitory G i/o proteins, because pre-treatment with pertussis toxin, but not over-expression of the G q/11 scavengers EBP50 and GRK2-K220R, prevented this effect. Further studies with Wortmannin and LY294002 revealed that phophoinositol-3-kinase (PI3K) plays a central role in opioid-induced Akt activation. Opioids stimulate Akt activity through transactivation of receptor tyrosine kinases (RTK), because pre-treatment of the cells with inhibitors for neurotrophin receptor tyrosine kinases (AG879) and the insulin-like growth factor receptor IGF-1 (AG1024), but not over-expression of the Gβγ scavenger phosducin, abolished this effect. Activated Akt translocates to the nuclear membrane, where it promotes GSK3 phosphorylation and prevents caspase-3 cleavage, two key events mediating inhibition of cell apoptosis and enhancement of cell survival. Taken together, these results demonstrate that in NG108-15 hybrid cells DOR agonists possess cytoprotective properties mediated by activation of the RTK/PI3K/Akt signaling pathway.

  9. Multiple Roles of the Extracellular Vestibule Amino Acid Residues in the Function of the Rat P2X4 Receptor

    Czech Academy of Sciences Publication Activity Database

    Rokic, Milos Boro; Stojilkovic, S. S.; Vávra, Vojtěch; Kuzyk, Pavlo; Tvrdoňová, Vendula; Zemková, Hana

    2013-01-01

    Roč. 8, č. 3 (2013), e59411 E-ISSN 1932-6203 R&D Projects: GA AV ČR(CZ) IAA500110910; GA ČR(CZ) GBP304/12/G069 Institutional research plan: CEZ:AV0Z50110509 Institutional support: RVO:67985823 Keywords : ATP * purinergic P2X receptor channels * transmembrane domain * extracellular vestibule * gating * ivermectin Subject RIV: ED - Physiology Impact factor: 3.534, year: 2013

  10. Mutated CaV2.1 channels dysregulate CASK/P2X3 signaling in mouse trigeminal sensory neurons of R192Q Cacna1a knock-in mice.

    Science.gov (United States)

    Gnanasekaran, Aswini; Bele, Tanja; Hullugundi, Swathi; Simonetti, Manuela; Ferrari, Michael D; van den Maagdenberg, Arn M J M; Nistri, Andrea; Fabbretti, Elsa

    2013-12-02

    ATP-gated P2X3 receptors of sensory ganglion neurons are important transducers of pain as they adapt their expression and function in response to acute and chronic nociceptive signals. The present study investigated the role of calcium/calmodulin-dependent serine protein kinase (CASK) in controlling P2X3 receptor expression and function in trigeminal ganglia from Cacna1a R192Q-mutated knock-in (KI) mice, a genetic model for familial hemiplegic migraine type-1. KI ganglion neurons showed more abundant CASK/P2X3 receptor complex at membrane level, a result that likely originated from gain-of-function effects of R192Q-mutated CaV2.1 channels and downstream enhanced CaMKII activity. The selective CaV2.1 channel blocker ω-Agatoxin IVA and the CaMKII inhibitor KN-93 were sufficient to return CASK/P2X3 co-expression to WT levels. After CASK silencing, P2X3 receptor expression was decreased in both WT and KI ganglia, supporting the role of CASK in P2X3 receptor stabilization. This process was functionally observed as reduced P2X3 receptor currents. We propose that, in trigeminal sensory neurons, the CASK/P2X3 complex has a dynamic nature depending on intracellular calcium and related signaling, that are enhanced in a transgenic mouse model of genetic hemiplegic migraine.

  11. Regulation of rat hepatocyte function by P2Y receptors: focus on control of glycogen phosphorylase and cyclic AMP by 2-methylthioadenosine 5'-diphosphate.

    Science.gov (United States)

    Dixon, C Jane; Hall, John F; Webb, Tania E; Boarder, Michael R

    2004-10-01

    Hepatocyte function is regulated by several P2Y receptor subtypes. Here we report that 2-methylthioadenosine 5'-diphosphate (2-MeSADP), an agonist at P2Y(1), P2Y(12), and P2Y(13) receptors, potently (threshold 30 nM) stimulates glycogen phosphorylase in freshly isolated rat hepatocytes. Antagonism by N(6)-methyl 2'-deoxyadenosine 3',5'-bisphosphate (MRS 2179) confirms that this response is mediated by P2Y(1) receptors. In addition, in these cells, both 2-MeSADP and UTP inhibited glucagon-stimulated cyclic AMP accumulation. This inhibitory effect of 2-MeSADP was not reversed by the P2Y(1) antagonists, adenosine-3'-phosphate-5'-phosphate (A3P5P) or MRS 2179, both in the range 1 to 300 microM, indicating that it was not mediated by P2Y(1) receptors. This contrasts with the increase in cytosolic free Ca(2+) concentration ([Ca(2+)](c)) induced by 2-MeSADP, which has shown to be inhibited by A3P5P. Pertussis toxin abolished the inhibitory effect of both UTP and 2-MeSADP. After culture of cells for 48 h, the ability of 2-MeSADP to inhibit cyclic AMP accumulation was greatly diminished. Reverse transcriptase-polymerase chain reaction analysis revealed that during this culture period, there was a decline in the ability to detect transcripts for P2Y(12) and P2Y(13) receptors, both of which are activated by 2-MeSADP and negatively coupled to adenylyl cyclase. However, in freshly isolated cells, the P2Y(12) and P2Y(13) receptor antagonist, 2-propylthio-beta,gamma-dichloromethylene-d-ATP (AR-C67085) (10 nM to 300 microM) did not alter the ability of 2-MeSADP to inhibit glucagon-stimulated cyclic AMP accumulation. We conclude that 2-MeSADP regulates rat hepatocyte glycogen phosphorylase by acting on P2Y(1) receptors coupled to raised [Ca(2+)](c), and by inhibiting cyclic AMP levels by an unknown G(i)-coupled receptor subtype, distinct from P2Y(1), P2Y(12), or P2Y(13) receptors.

  12. Quantification of mutation-derived bias for alternate mating functionalities of the Saccharomyces cerevisiae Ste2p pheromone receptor.

    Science.gov (United States)

    Choudhary, Pooja; Loewen, Michele C

    2016-01-01

    Although well documented for mammalian G-protein-coupled receptors, alternate functionalities and associated alternate signalling remain to be unequivocally established for the Saccharomyces cerevisiae pheromone Ste2p receptor. Here, evidence supporting alternate functionalities for Ste2p is re-evaluated, extended and quantified. In particular, strong mating and constitutive signalling mutations, focusing on residues S254, P258 and S259 in TM6 of Ste2p, are stacked and investigated in terms of their effects on classical G-protein-mediated signal transduction associated with cell cycle arrest, and alternatively, their impact on downstream mating projection and zygote formation events. In relative dose response experiments, accounting for systemic and observational bias, mutational-derived functional differences were observed, validating the S254L-derived bias for downstream mating responses and highlighting complex relationships between TM6-mutation derived constitutive signalling and ligand-induced functionalities. Mechanistically, localization studies suggest that alterations to receptor trafficking may contribute to mutational bias, in addition to expected receptor conformational stabilization effects. Overall, these results extend previous observations and quantify the contributions of Ste2p variants to mediating cell cycle arrest versus downstream mating functionalities. © Crown copyright 2015.

  13. Ionotropic NMDA and P2X1/5 receptors mediate synaptically induced Ca2+ signalling in cortical astrocytes

    Czech Academy of Sciences Publication Activity Database

    Palygin, O.; Lalo, U.; Verkhratsky, Alexei; Pankratov, Y.

    2010-01-01

    Roč. 48, č. 4 (2010), s. 225-231 ISSN 0143-4160 R&D Projects: GA ČR GA305/08/1384 Institutional research plan: CEZ:AV0Z50390703 Keywords : Astroglia * Ca2+ signalling * NMDA receptors Subject RIV: FH - Neurology Impact factor: 3.553, year: 2010

  14. NK cell cytotoxicity mediated by 2B4 and NTB-A is dependent on SAP acting downstream of receptor phosphorylation

    Directory of Open Access Journals (Sweden)

    Stephan eMeinke

    2013-01-01

    Full Text Available 2B4 (CD244 and NK-T-B-antigen (NTB-A, CD352 are activating receptors on human NK cells and belong to the family of SLAM-related receptors. Engagement of these receptors leads to phosphorylation of their cytoplasmic tails and recruitment of the adapter proteins SAP and EAT-2. X-linked lymphoproliferative syndrome (XLP is a severe immunodeficiency that results from mutations in the SAP gene. 2B4 and NTB-A-mediated cytotoxicity are abrogated in XLP NK cells. To elucidate the molecular basis for this defect we analyzed early signaling events in SAP knockdown cells. Similar to XLP NK cells, knockdown of SAP in primary human NK cells leads to a reduction of 2B4 and NTB-A-mediated cytotoxicity. We found that early signaling events such as raft recruitment and receptor phosphorylation are not affected by the absence of SAP, indicating the defect in the absence of SAP is downstream of these events. In addition, knockdown of EAT-2 does not impair 2B4 or NTB-A-mediated cytotoxicity. Surprisingly, EAT-2 recruitment to both receptors is abrogated in the absence of SAP, revealing a novel cooperativity between these adapters.

  15. Characterization of P2Y receptors mediating ATP induced relaxation in guinea pig airway smooth muscle: involvement of prostaglandins and K+ channels.

    Science.gov (United States)

    Montaño, Luis M; Cruz-Valderrama, José E; Figueroa, Alejandra; Flores-Soto, Edgar; García-Hernández, Luz M; Carbajal, Verónica; Segura, Patricia; Méndez, Carmen; Díaz, Verónica; Barajas-López, Carlos

    2011-10-01

    In airway smooth muscle (ASM), adenosine 5'-triphosphate (ATP) induces a relaxation associated with prostaglandin production. We explored the role of K(+) currents (I (K)) in this relaxation. ATP relaxed the ASM, and this effect was abolished by indomethacin. Removal of airway epithelium slightly diminished the ATP-induced relaxation at lower concentration without modifying the responses to ATP at higher concentrations. ATPγS and UTP induced a concentration-dependent relaxation similar to ATP; α,β-methylene-ATP was inactive from 1 to 100 μM. Suramin or reactive blue 2 (RB2), P2Y receptor antagonists, did not modify the relaxation, but their combination significantly reduced this effect of ATP. The relaxation was also inhibited by N-ethylmaleimide (NEM; which uncouples G proteins). In myocytes, the ATP-induced I (K) increment was not modified by suramin or RB2 but the combination of both drugs abolished it. This increment in the I (K) was also completely nullified by NEM and SQ 22,536. 4-Amynopyridine or iberiotoxin diminished the ATP-induced I (K) increment, and the combination of both substances diminished ATP-induced relaxation. The presence of P2Y(2) and P2Y(4) receptors in smooth muscle was corroborated by Western blot and confocal images. In conclusion, ATP: (1) produces relaxation by inducing the production of bronchodilator prostaglandins in airway smooth muscle, most likely by acting on P2Y(4) and P2Y(2) receptors; (2) induces I (K) increment through activation of the delayed rectifier K(+) channels and the high-conductance Ca(2+)-dependent K(+) channels, therefore both channels are implicated in the ATP-induced relaxation; and (3) this I (K) increment is mediated by prostaglandin production which in turns increase cAMP signaling pathway.

  16. CDK11{sup p58} represses vitamin D receptor-mediated transcriptional activation through promoting its ubiquitin-proteasome degradation

    Energy Technology Data Exchange (ETDEWEB)

    Chi, Yayun; Hong, Yi; Zong, Hongliang; Wang, Yanlin; Zou, Weiying; Yang, Junwu; Kong, Xiangfei; Yun, Xiaojing [Gene Research Center, Shanghai Medical College and Institutes of Biomedical, Shanghai 200032 (China); Gu, Jianxin, E-mail: jxgu@shmu.edu.cn [Gene Research Center, Shanghai Medical College and Institutes of Biomedical, Shanghai 200032 (China)

    2009-08-28

    Vitamin D receptor (VDR) is a member of the nuclear receptor superfamily and regulates transcription of target genes. In this study, we identified CDK11{sup p58} as a novel protein involved in the regulation of VDR. CDK11{sup p58}, a member of the large family of p34cdc2-related kinases, is associated with cell cycle progression, tumorigenesis, and apoptotic signaling. Our study demonstrated that CDK11{sup p58} interacted with VDR and repressed VDR-dependent transcriptional activation. Furthermore, overexpression of CDK11{sup p58} decreased the stability of VDR through promoting its ubiquitin-proteasome-mediated degradation. Taken together, these results suggest that CDK11{sup p58} is involved in the negative regulation of VDR.

  17. PKCɛ mediates substance P inhibition of GABAA receptors-mediated current in rat dorsal root ganglion.

    Science.gov (United States)

    Li, Li; Zhao, Lei; Wang, Yang; Ma, Ke-tao; Shi, Wen-yan; Wang, Ying-zi; Si, Jun-qiang

    2015-02-01

    The mechanism underlying the modulatory effect of substance P (SP) on GABA-activated response in rat dorsal root ganglion (DRG) neurons was investigated. In freshly dissociated rat DRG neurons, whole-cell patch-clamp technique was used to record GABA-activated current and sharp electrode intracellular recording technique was used to record GABA-induced membrane depolarization. Application of GABA (1-1000 μmol/L) induced an inward current in a concentration-dependent manner in 114 out of 127 DRG neurons (89.8 %) examined with whole-cell patch-clamp recordings. Bath application of GABA (1-1000 μmol/L) evoked a depolarizing response in 236 out of 257 (91.8%) DRG neurons examined with intracellular recordings. Application of SP (0.001-1 μmol/L) suppressed the GABA-activated inward current and membrane depolarization. The inhibitory effects were concentration-dependent and could be blocked by the selective neurokinin 1 (NK1) receptors antagonist spantide but not by L659187 and SR142801 (1 μmol/L, n=7), selective antagonists of NK2 and NK3. The inhibitory effect of SP was significantly reduced by the calcium chelator BAPTA-AM, phospholipase C (PLC) inhibitor U73122, and PKC inhibitor chelerythrine, respectively. The PKA inhibitor H-89 did not affect the SP effect. Remarkably, the inhibitory effect of SP on GABA-activated current was nearly completely removed by a selective PKCε inhibitor epilon-V1-2 but not by safingol and LY333531, selective inhibitors of PKCα and PKCβ. Our results suggest that NK1 receptor mediates SP-induced inhibition of GABA-activated current and membrane depolarization by activating intracellular PLC-Ca²⁺-PKCε cascade. SP might regulate the excitability of peripheral nociceptors through inhibition of the "pre-synaptic inhibition" evoked by GABA, which may explain its role in pain and neurogenic inflammation.

  18. P2X7 receptor-mediated analgesia in cancer-induced bone pain

    DEFF Research Database (Denmark)

    Falk, Sarah; D. Schwab, Samantha; Frøsig-Jørgensen, Majbrit

    2015-01-01

    Pain is a common and debilitating complication for cancer patients significantly compromising their quality of life. Cancer-induced bone pain involves a complex interplay of molecular events, including mechanisms observed in inflammatory and neuropathic pain states, but also changes unique for ca...

  19. The retinoid X receptor agonist, 9-cis UAB30, inhibits cutaneous T-cell lymphoma proliferation through the SKP2-p27kip1 axis.

    Science.gov (United States)

    Chou, Chu-Fang; Hsieh, Yu-Hua; Grubbs, Clinton J; Atigadda, Venkatram R; Mobley, James A; Dummer, Reinhard; Muccio, Donald D; Eto, Isao; Elmets, Craig A; Garvey, W Timothy; Chang, Pi-Ling

    2018-06-01

    Bexarotene (Targretin ® ) is currently the only FDA approved retinoid X receptor (RXR) -selective agonist for the treatment of cutaneous T-cell lymphomas (CTCLs). The main side effects of bexarotene are hypothyroidism and elevation of serum triglycerides (TGs). The novel RXR ligand, 9-cis UAB30 (UAB30) does not elevate serum TGs or induce hypothyroidism in normal subjects. To assess preclinical efficacy and mechanism of action of UAB30 in the treatment of CTCLs and compare its action with bexarotene. With patient-derived CTCL cell lines, we evaluated UAB30 function in regulating growth, apoptosis, cell cycle check points, and cell cycle-related markers. Compared to bexarotene, UAB30 had lower half maximal inhibitory concentration (IC 50 ) values and was more effective in inhibiting the G1 cell cycle checkpoint. Both rexinoids increased the stability of the cell cycle inhibitor, p27kip1 protein, in part, through targeting components involved in the ubiquitination-proteasome system: 1) decreasing SKP2, a F-box protein that binds and targets p27kip1 for degradation by 26S proteasome and 2) suppressing 20S proteasome activity (cell line-dependent) through downregulation of PSMA7, a component of the 20S proteolytic complex in 26S proteasome. UAB30 and bexarotene induce both early cell apoptosis and suppress cell proliferation. Inhibition of the G1 to S cell cycle transition by rexinoids is mediated, in part, through downregulation of SKP2 and/or 20S proteasome activity, leading to increased p27kip1 protein stability. Because UAB30 has minimal effect in elevating serum TGs and inducing hypothyroidism, it is potentially a better alternative to bexarotene for the treatment of CTCLs. Copyright © 2018 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.

  20. Transmembrane α-Helix 2 and 7 Are Important for Small Molecule-Mediated Activation of the GLP-1 Receptor

    DEFF Research Database (Denmark)

    Underwood, Christina Rye; Møller Knudsen, Sanne; Schjellerup Wulff, Birgitte

    2011-01-01

    Glucagon-like peptide-1 (GLP-1) activates the GLP-1 receptor (GLP-1R), which belongs to family B of the G-protein-coupled receptors. We previously identified a selective small molecule ligand, compound 2, that acted as a full agonist and allosteric modulator of GLP-1R. In this study, the structur......Glucagon-like peptide-1 (GLP-1) activates the GLP-1 receptor (GLP-1R), which belongs to family B of the G-protein-coupled receptors. We previously identified a selective small molecule ligand, compound 2, that acted as a full agonist and allosteric modulator of GLP-1R. In this study......, the structurally related small molecule, compound 3, stimulated cAMP production from GLP-1R, but not from the homologous glucagon receptor (GluR). The receptor selectivity encouraged a chimeric receptor approach to identify domains important for compound 3-mediated activation of GLP-1R. A subsegment of the GLP-1R...... transmembrane domain containing TM2 to TM5 was sufficient to transfer compound 3 responsiveness to GluR. Therefore, divergent residues in this subsegment of GLP-1R and GluR are responsible for the receptor selectivity of compound 3. Functional analyses of other chimeric receptors suggested that the existence...

  1. Interference by 2,3,7,8-tetrachlorodibenzo-p-dioxin with cultured mouse submandibular gland branching morphogenesis involves reduced epidermal growth factor receptor signaling

    International Nuclear Information System (INIS)

    Kiukkonen, Anu; Sahlberg, Carin; Partanen, Anna-Maija; Alaluusua, Satu; Pohjanvirta, Raimo; Tuomisto, Jouko; Lukinmaa, Pirjo-Liisa

    2006-01-01

    Toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to mouse embryonic teeth, sharing features of early development with salivary glands in common, involves enhanced apoptosis and depends on the expression of epidermal growth factor (EGF) receptor. EGF receptor signaling, on the other hand, is essential for salivary gland branching morphogenesis. To see if TCDD impairs salivary gland morphogenesis and if the impairment is associated with EGF receptor signaling, we cultured mouse (NMRI) E13 submandibular glands with TCDD or TCDD in combination with EGF or fibronectin (FN), both previously found to enhance branching morphogenesis. Explants were examined stereomicroscopically and processed to paraffin sections. TCDD exposure impaired epithelial branching and cleft formation, resulting in enlarged buds. The glands were smaller than normal. EGF and FN alone concentration-dependently stimulated or inhibited branching morphogenesis but when co-administered with TCDD, failed to compensate for its effect. TCDD induced cytochrome P4501A1 expression in the glandular epithelium, indicating activation of the aryl hydrocarbon receptor. TCDD somewhat increased epithelial apoptosis as observed by terminal deoxynucleotidyl transferase (TdT)-mediated nick end-labeling method but the increase could not be correlated with morphological changes. The frequency of proliferating cells was not altered. Corresponding to the reduced cleft sites in TCDD-exposed explants, FN immunoreactivity in the epithelium was reduced. The results show that TCDD, comparably with EGF and FN at morphogenesis-inhibiting concentrations, impaired salivary gland branching morphogenesis in vitro. Together with the failure of EGF and FN at morphogenesis-stimulating concentrations to compensate for the effect of TCDD this implies that TCDD toxicity to developing salivary gland involves reduced EGF receptor signaling

  2. Pannexin channels mediate the acquisition of myogenic commitment in C2C12 reserve cells promoted by P2 receptor activation

    Science.gov (United States)

    Riquelme, Manuel A.; Cea, Luis A.; Vega, José L.; Puebla, Carlos; Vargas, Aníbal A.; Shoji, Kenji F.; Subiabre, Mario; Sáez, Juan C.

    2015-01-01

    The acquisition of myoblast commitment to the myogenic linage requires rises in intracellular free Ca2+ concentration ([Ca2+]i). Putative cell membrane pathways involved in these [Ca2+]i increments are P2 receptors (P2Rs) as well as connexin (Cx) and/or pannexin (Panx) hemichannels and channels (Cx HChs and Panx Chs), respectively, which are known to permeate Ca2+. Reserve cells (RCs) are uncommitted myoblasts obtained from differentiated C2C12 cell cultures, which acquire commitment upon replating. Regarding these cells, we found that extracellular ATP increases the [Ca2+]i via P2Rs. Moreover, ATP increases the plasma membrane permeability to small molecules and a non-selective membrane current, both of which were inhibited by Cx HCh/Panx1Ch blockers. However, RCs exposed to divalent cation-free saline solution, which is known to activate Cx HChs (but not Panx Chs), did not enhance membrane permeability, thus ruling out the possible involvement of Cx HChs. Moreover, ATP-induced membrane permeability was inhibited with blockers of P2Rs that activate Panx Chs. In addition, exogenous ATP induced the expression of myogenic commitment and increased MyoD levels, which was prevented by the inhibition of P2Rs or knockdown of Panx1 Chs. Similarly, increases in MyoD levels induced by ATP released by RCs were inhibited by Panx Ch/Cx HCh blockers. Myogenic commitment acquisition thus requires a feed-forward mechanism mediated by extracellular ATP, P2Rs, and Panx Chs. PMID:26000275

  3. Clathrin-dependent internalization of the angiotensin II AT₁A receptor links receptor internalization to COX-2 protein expression in rat aortic vascular smooth muscle cells.

    Science.gov (United States)

    Morinelli, Thomas A; Walker, Linda P; Velez, Juan Carlos Q; Ullian, Michael E

    2015-02-05

    The major effects of Angiotensin II (AngII) in vascular tissue are mediated by AngII AT1A receptor activation. Certain effects initiated by AT1A receptor activation require receptor internalization. In rat aortic vascular smooth muscle cells (RASMC), AngII stimulates cyclooxygenase 2 protein expression. We have previously shown this is mediated by β-arrestin-dependent receptor internalization and NF-κB activation. In this study, a specific inhibitor of clathrin-mediated endocytosis (CME), pitstop-2, was used to test the hypothesis that clathrin-dependent internalization of activated AT1A receptor mediates NF-κB activation and subsequent cyclooxygenase 2 expression. Radioligand binding assays, real time qt-PCR and immunoblotting were used to document the effects of pitstop-2 on AngII binding and signaling in RASMC. Laser scanning confocal microscopy (LSCM) was used to image pitstop-2׳s effects on AT1 receptor/GFP internalization in HEK-293 cells and p65 NF-κB nuclear localization in RASMC. Pitstop-2 significantly inhibited internalization of AT1A receptor (44.7% ± 3.1% Control vs. 13.2% ± 8.3% Pitstop-2; n=3) as determined by radioligand binding studies in RASMC. Studies utilizing AT1A receptor/GFP expressed in HEK 293 cells and LSCM confirmed these findings. Pitstop-2 significantly inhibited AngII-induced p65 NF-κB phosphorylation and nuclear localization, COX-2 message and protein expression in RASMC without altering activation of p42/44 ERK or TNFα signaling. Pitstop-2, a specific inhibitor of clathrin-mediated endocytosis, confirms that internalization of activated AT1A receptor mediates AngII activation of cyclooxygenase 2 expression in RASMC. These data provide support for additional intracellular signaling pathways activated through β-arrestin mediated internalization of G protein-coupled receptors, such as AT1A receptors. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. N-isopropyl-p-iodoamphetamine receptors in normal and cancerous tissue of the human lung

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Eiko; Mishima, Michiaki; Kawakami, Kenzo; Sakai, Naoki; Sugiura, Naoharu; Kuno, Kenshi [Kyoto Univ. (Japan). Dept. of Clinical Physiology; Taniguchi, Takashi [Kyoto Pharmaceutical Univ. (Japan). Dept. of Neurobiology

    1993-04-01

    N-Isopropyl-p-iodoamphetamine (IMP) receptors in normal human lung tissue were characterized using a radioligand binding assay with iodine-125 IMP as the ligand. Saturation binding studies revealed the presence of two binding sites with dissociation constant (K[sub d]) values of 53[+-]2 and 4687[+-]124 nM and maximum binding capacity (Bmax) values of 7[+-]1 and 133[+-]27 pmol/mg protein (n=5) respectively. The IC[sub 50] values of various amines were as follows: IMP, 9x10[sup -5] M; propranolol, 5x10[sup -4] M; haloperidol, 6x10[sup -4] M; ketamine, 9x10[sup -3] M; dopamine, 1x10[sup -2] M. The IMP receptors of cancerous tissue obtained from human lung also had two binding sites with K[sub d] values of 54[+-]2 and 5277[+-]652 nM and Bmax values of 7[+-]1 and 103[+-]21 pmol/mg protein (n=3) respectively. There was no significant difference in binding parameters between normal and cancerous lung tissue. These results demonstrate the existence of IMP receptors and suggest that cancer does not affect the nature of IMP receptors in human lung tissue. (orig.).

  5. ARF6-dependent regulation of P2Y receptor traffic and function in human platelets.

    Science.gov (United States)

    Kanamarlapudi, Venkateswarlu; Owens, Sian E; Saha, Keya; Pope, Robert J; Mundell, Stuart J

    2012-01-01

    Adenosine diphosphate (ADP) is a critical regulator of platelet activation, mediating its actions through two G protein-coupled receptors, the P2Y(1) and P2Y(12) purinoceptors. Recently, we demonstrated that P2Y(1) and P2Y(12) purinoceptor activities are rapidly and reversibly modulated in human platelets, revealing that the underlying mechanism requires receptor internalization and subsequent trafficking as an essential part of this process. In this study we investigated the role of the small GTP-binding protein ADP ribosylation factor 6 (ARF6) in the internalization and function of P2Y(1) and P2Y(12) purinoceptors in human platelets. ARF6 has been implicated in the internalization of a number of GPCRs, although its precise molecular mechanism in this process remains unclear. In this study we show that activation of either P2Y(1) or P2Y(12) purinoceptors can stimulate ARF6 activity. Further blockade of ARF6 function either in cell lines or human platelets blocks P2Y purinoceptor internalization. This blockade of receptor internalization attenuates receptor resensitization. Furthermore, we demonstrate that Nm23-H1, a nucleoside diphosphate (NDP) kinase regulated by ARF6 which facilitates dynamin-dependent fission of coated vesicles during endocytosis, is also required for P2Y purinoceptor internalization. These data describe a novel function of ARF6 in the internalization of P2Y purinoceptors and demonstrate the integral importance of this small GTPase upon platelet ADP receptor function.

  6. ARF6-dependent regulation of P2Y receptor traffic and function in human platelets.

    Directory of Open Access Journals (Sweden)

    Venkateswarlu Kanamarlapudi

    Full Text Available Adenosine diphosphate (ADP is a critical regulator of platelet activation, mediating its actions through two G protein-coupled receptors, the P2Y(1 and P2Y(12 purinoceptors. Recently, we demonstrated that P2Y(1 and P2Y(12 purinoceptor activities are rapidly and reversibly modulated in human platelets, revealing that the underlying mechanism requires receptor internalization and subsequent trafficking as an essential part of this process. In this study we investigated the role of the small GTP-binding protein ADP ribosylation factor 6 (ARF6 in the internalization and function of P2Y(1 and P2Y(12 purinoceptors in human platelets. ARF6 has been implicated in the internalization of a number of GPCRs, although its precise molecular mechanism in this process remains unclear. In this study we show that activation of either P2Y(1 or P2Y(12 purinoceptors can stimulate ARF6 activity. Further blockade of ARF6 function either in cell lines or human platelets blocks P2Y purinoceptor internalization. This blockade of receptor internalization attenuates receptor resensitization. Furthermore, we demonstrate that Nm23-H1, a nucleoside diphosphate (NDP kinase regulated by ARF6 which facilitates dynamin-dependent fission of coated vesicles during endocytosis, is also required for P2Y purinoceptor internalization. These data describe a novel function of ARF6 in the internalization of P2Y purinoceptors and demonstrate the integral importance of this small GTPase upon platelet ADP receptor function.

  7. Expression of the P2X2 receptor in different classes of ileum myenteric neurons in the female obese ob/ob mouse

    Science.gov (United States)

    Mizuno, Márcia Sanae; Crisma, Amanda Rabello; Borelli, Primavera; Castelucci, Patricia

    2012-01-01

    AIM: To examine whether the ob/ob mouse model of obesity is accompanied by enteric nervous system abnormalities such as altered motility. METHODS: The study examined the distribution of the P2X2 receptor (P2X2R) in myenteric neurons of female ob/ob mice. Specifically, we used immunohistochemistry to analyze the co-expression of the P2X2R with neuronal nitric oxide synthase (nNOS), choline acetyltransferase (ChAT), and calretinin (CalR) in neurons of the small intestine myenteric plexus in ob/ob and control female mice. In these sections, we used scanning confocal microscopy to analyze the co-localization of these markers as well as the neuronal density (cm2) and area profile (μm²) of P2X2R-positive neurons. In addition, enteric neurons were labeled using the nicotinamide adenine dinucleotide (NADH) diaphorase method and analyzed with light microscopy as an alternate means by which to analyze neuronal density and area. RESULTS: In the present study, we observed a 29.6% increase in the body weight of the ob/ob animals (OG) compared to the control group (CG). In addition, the average small intestine area was increased by approximately 29.6% in the OG compared to the CG. Immunoreactivity (IR) for the P2X2R, nNOS, ChAT and CalR was detectable in the myenteric plexus, as well as in the smooth muscle, in both groups. This IR appeared to be mainly cytoplasmic and was also associated with the cell membrane of the myenteric plexus neurons, where it outlined the neuronal cell bodies and their processes. P2X2R-IR was observed to co-localize 100% with that for nNOS, ChAT and CalR in neurons of both groups. In the ob/ob group, however, we observed that the neuronal density (neuron/cm2) of P2X2R-IR cells was increased by 62% compared to CG, while that of NOS-IR and ChAT-IR neurons was reduced by 49% and 57%, respectively, compared to control mice. The neuronal density of CalR-IR neurons was not different between the groups. Morphometric studies further demonstrated that the

  8. Rationally designed chimeric peptide of met-enkephalin and FMRFa-[D-Ala2,p-Cl-Phe4]YFa induce multiple opioid receptors mediated antinociception and up-regulate their expression.

    Science.gov (United States)

    Vats, Ishwar Dutt; Chaudhary, Snehlata; Sharma, Ahuti; Nath, Mahendra; Pasha, Santosh

    2010-07-25

    The physiological role of NPFF/FMRFa family of peptides appears to be complex and exact mechanism of action of these peptides is not yet completely understood. In same line of scrutiny, another analog of YGGFMKKKFMRFamide (YFa), a chimeric peptide of met-enkephalin and FMRFamide, was rationally designed and synthesized which contain D-alanine and p-Cl-phenylalanine residues at 2nd and 4th positions, respectively i.e., Y-(D-Ala)-G-(p-Cl-Phe)-MKKKFMRFamide ([D-Ala(2), p-Cl-Phe(4)]YFa) in order to achieve improved bioavailability and blood brain barrier penetration. Therefore, present study investigates the possible antinociceptive effect of [D-Ala(2), p-Cl-Phe(4)]YFa on intra-peritoneal (i.p.) administration using tail-flick test in rats followed by its opioid receptor(s) specificity using mu, delta and kappa receptor antagonists. Further, its antinociceptive effect was examined during 6 days of chronic i.p. treatment and assessed effect of this treatment on differential expression of opioid receptors. [D-Ala(2), p-Cl-Phe(4)]YFa in comparison to parent peptide YFa, induce significantly higher dose dependent antinociception in rats which was mediated by all three opioid receptors (mu, delta and kappa). Importantly, it induced comparable antinociception in rats throughout the chronic i.p. treatment and significantly up-regulated the overall expression (mRNA and protein) of mu, delta and kappa opioid receptors. Therefore, pharmacological and molecular behavior of [D-Ala(2), p-Cl-Phe(4)]YFa demonstrate that incorporation of D-alanine and p-Cl-phenylalanine residues at appropriate positions in chimeric peptide leads to altered opioid receptor selectivity and enhanced antinociceptive potency, relative to parent peptide. (c) 2010 Elsevier B.V. All rights reserved.

  9. Transcriptional down-regulation of thromboxane A(2) receptor expression via activation of MAPK ERK1/2, p38/NF-kappaB pathways

    DEFF Research Database (Denmark)

    Zhang, Wei; Zhang, Yaping; Edvinsson, Lars

    2009-01-01

    culture of the arteries, VSMC TP receptors were studied by using myography, real-time PCR and immunohistochemistry. We observed that organ culture for 24 and 48 h resulted in depressed TP receptor-mediated contraction in the VSMC, in parallel with decreased TP receptor mRNA and protein expressions....... Phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2), p38 and nuclear factor-kappaB (NF-kappaB) was seen by Western blot within 1-3 h after organ culture. Inhibition of ERK1/2, p38 or NF-kappaB reversed depressed contraction as well as decreased receptor mRNA expression. Actinomycin D...

  10. Transcriptional Down-Regulation of Thromboxane A(2) Receptor Expression via Activation of MAPK ERK1/2, p38/NF-kappaB Pathways

    DEFF Research Database (Denmark)

    Zhang, Wei; Zhang, Yaping; Edvinsson, Lars

    2008-01-01

    culture of the arteries, VSMC TP receptors were studied by using myography, real-time PCR and immunohistochemistry. We observed that organ culture for 24 and 48 h resulted in depressed TP receptor-mediated contraction in the VSMC, in parallel with decreased TP receptor mRNA and protein expressions....... Phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2), p38 and nuclear factor-kappaB (NF-kappaB) was seen by Western blot within 1-3 h after organ culture. Inhibition of ERK1/2, p38 or NF-kappaB reversed depressed contraction as well as decreased receptor mRNA expression. Actinomycin D...

  11. Genetic Association for P2X7R rs3751142 and CARD8 rs2043211 Polymorphisms for Susceptibility of Gout in Korean Men: Multi-Center Study.

    Science.gov (United States)

    Lee, Sung Won; Lee, Shin Seok; Oh, Dong Ho; Park, Dong Jin; Kim, Hyun Sook; Choi, Jung Ran; Chae, Soo Cheon; Yun, Ki Jung; Chung, Won Tae; Choe, Jung Yoon; Kim, Seong Kyu

    2016-10-01

    The aim of this study was to determine the association between P2X7R rs3751142 and CARD8 rs2043211 polymorphisms and gout susceptibility in male Korean subjects. This study enrolled a total of 242 male patients with gout and 280 healthy controls. The polymorphisms of two individual genes including rs3751142(C>A) in the P2X7R gene and rs2043211(A>T) in the CARD8 gene were assessed using Taq-Man analysis. Statistical analyses were performed using the Chi-square test, Kruskal-Wallis test, and logistic regression analyses. A difference in genotypic frequency of the P2X7R rs3751142 and CARD8 rs2043211 genes was not detected between gout and control patients. Clinical parameters including age, onset age, disease duration, body mass index, and serum uric acid levels were not different among the three genotypes for either P2X7R or CARD8 (P > 0.05 for all). A pair-wise comparison of P2X7R rs3751142 and CARD8 rs2043211 genotype combinations revealed that subjects with the CA P2X7R rs3751142 genotype and the TT CARD8 rs2043211 genotype had a trend toward a higher risk of gout compared to the CC/AA combination (P = 0.056, OR = 2.618, 95% CI 0.975 - 7.031). In conclusion, this study revealed that genetic variability of the P2X7R rs3751142 and CARD8 rs2043211 genes might, in part, be associated with susceptibility for gout.

  12. Na3Co2(As0.52P0.48)O4(As0.95P0.05)2O7.

    Science.gov (United States)

    Ben Smida, Youssef; Guesmi, Abderrahmen; Zid, Mohamed Faouzi; Driss, Ahmed

    2013-11-30

    The title compound, trisodium dicobalt(II) (arsenate/phosphate) (diarsenate/diphosphate), was prepared by a solid-state reaction. It is isostructural with Na3Co2AsO4As2O7. The framework shows the presence of CoX22O12 (X2 is statistically disordered with As0.95P0.05) units formed by sharing corners between Co1O6 octa-hedra and X22O7 groups. These units form layers perpendicular to [010]. Co2O6 octa-hedra and X1O4 (X1 = As0.54P0.46) tetra-hedra form Co2X1O8 chains parallel to [001]. Cohesion between layers and chains is ensured by the X22O7 groups, giving rise to a three-dimensional framework with broad tunnels, running along the a- and c-axis directions, in which the Na(+) ions reside. The two Co(2+) cations, the X1 site and three of the seven O atoms lie on special positions, with site symmetries 2 and m for the Co, m for the X1, and 2 and m (× 2) for the O sites. One of two Na atoms is disordered over three special positions [occupancy ratios 0.877 (10):0.110 (13):0.066 (9)] and the other is in a general position with full occupancy. A comparison between structures such as K2CdP2O7, α-NaTiP2O7 and K2MoO2P2O7 is made. The proposed structural model is supported by charge-distribution (CHARDI) analysis and bond-valence-sum (BVS) calculations. The distortion of the coordination polyhedra is analyzed by means of the effective coordination number.

  13. Neurotrophin receptor p75NTR mediates Huntington’s disease–associated synaptic and memory dysfunction

    Science.gov (United States)

    Brito, Verónica; Giralt, Albert; Enriquez-Barreto, Lilian; Puigdellívol, Mar; Suelves, Nuria; Zamora-Moratalla, Alfonsa; Ballesteros, Jesús J.; Martín, Eduardo D.; Dominguez-Iturza, Nuria; Morales, Miguel; Alberch, Jordi; Ginés, Sílvia

    2014-01-01

    Learning and memory deficits are early clinical manifestations of Huntington’s disease (HD). These cognitive impairments have been mainly associated with frontostriatal HD pathology; however, compelling evidence provided by several HD murine models suggests that the hippocampus may contribute to synaptic deficits and memory dysfunction in HD. The neurotrophin receptor p75NTR negatively regulates spine density, which is associated with learning and memory; therefore, we explored whether disturbed p75NTR function in the hippocampus could contribute to synaptic dysfunction and memory deficits in HD. Here, we determined that levels of p75NTR are markedly increased in the hippocampus of 2 distinct mouse models of HD and in HD patients. Normalization of p75NTR levels in HD mutant mice heterozygous for p75NTR prevented memory and synaptic plasticity deficits and ameliorated dendritic spine abnormalities, likely through normalization of the activity of the GTPase RhoA. Moreover, viral-mediated overexpression of p75NTR in the hippocampus of WT mice reproduced HD learning and memory deficits, while knockdown of p75NTR in the hippocampus of HD mice prevented cognitive decline. Together, these findings provide evidence of hippocampus-associated memory deficits in HD and demonstrate that p75NTR mediates synaptic, learning, and memory dysfunction in HD. PMID:25180603

  14. P2Y2 receptor knock-out mice display normal NaCl absorption in medullary thick ascending limb

    Directory of Open Access Journals (Sweden)

    Rita Delgado Marques

    2013-10-01

    Full Text Available Local purinergic signals modulate renal tubular transport. Acute activation of renal epithelial P2 receptors causes inhibition of epithelial transport and thus, should favor increased water and salt excretion by the kidney. So far only a few studies have addressed the effects of extracellular nucleotides on ion transport in the thick ascending limb. In the medullary thick ascending limb (mTAL, basolateral P2X receptors markedly (~25% inhibit NaCl absorption. Although this segment does express both apical and basolateral P2Y2 receptors, acute activation of the basolateral P2Y2 receptors had no apparent effect on transepithelial ion transport. Here we studied, if the absence of the P2Y2 receptor causes chronic alterations in mTAL NaCl absorption by comparing basal and AVP-stimulated transepithelial transport rates. We used perfused mouse mTALs to electrically measure NaCl absorption in juvenile (35 days male mice. Using microelectrodes, we determined the transepithelial voltage (Vte and the transepithelial resistance (Rte and thus, transepithelial NaCl absorption (equivalent short circuit current, I’sc.We find that mTALs from adult wild type (WT mice have significantly lower NaCl absorption rates when compared to mTALs from juvenile WT mice. This could be attributed to significantly higher Rte values in mTALs from adult WT mice. This pattern was not observed in mTALs from P2Y2 receptor knockout (KO mice. In addition, adult P2Y2 receptor KO mTALs have significantly lower Vte values compared to the juvenile. No difference in absolute I´sc was observed when comparing mTALs from WT and KO mice. AVP stimulated the mTALs to similar increases of NaCl absorption irrespective of the absence of the P2Y2 receptor. No difference was observed in the medullary expression level of NKCC2 in between the genotypes.These data indicate that the lack of P2Y2 receptors does not cause substantial differences in resting and AVP-stimulated NaCl absorption in

  15. Pharmacological significance of the interplay between angiotensin receptors: MAS receptors as putative final mediators of the effects elicited by angiotensin AT1 receptors antagonists.

    Science.gov (United States)

    Pernomian, Larissa; Pernomian, Laena; Gomes, Mayara S; da Silva, Carlos H T P

    2015-12-15

    The interplay between angiotensin AT1 receptors and MAS receptors relies on several inward regulatory mechanisms from renin-angiotensin system (RAS) including the functional crosstalk between angiotensin II and angiotensin-(1-7), the competitive AT1 antagonism exhibited by angiotensin-(1-7), the antagonist feature assigned to AT1/MAS heterodimerization on AT1 signaling and the AT1-mediated downregulation of angiotensin-converting enzyme 2 (ACE2). Recently, such interplay has acquired an important significance to RAS Pharmacology since a few studies have supporting strong evidences that MAS receptors mediate the effects elicited by AT1 antagonists. The present Perspective provides an overview of the regulatory mechanisms involving AT1 and MAS receptors, their significance to RAS Pharmacology and the future directions on the interplay between angiotensin receptors. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Mediator-dependent Nuclear Receptor Functions

    Science.gov (United States)

    Chen, Wei; Roeder, Robert

    2011-01-01

    As gene-specific transcription factors, nuclear hormone receptors are broadly involved in many important biological processes. Their function on target genes requires the stepwise assembly of different coactivator complexes that facilitate chromatin remodeling and subsequent preinitiation complex (PIC) formation and function. Mediator has proved to be a crucial, and general, nuclear receptor-interacting coactivator, with demonstrated functions in transcription steps ranging from chromatin remodeling to subsequent PIC formation and function. Here we discuss (i) our current understanding of pathways that nuclear receptors and other interacting cofactors employ to recruit Mediator to target gene enhancers and promoters, including conditional requirements for the strong NR-Mediator interactions mediated by the NR AF2 domain and the MED1 LXXLLL motifs and (ii) mechanisms by which Mediator acts to transmit signals from enhancer-bound nuclear receptors to the general transcription machinery at core promoters to effect PIC formation and function. PMID:21854863

  17. Targeting B7x and B7-H3 as New Immunotherapies for Prostate Cancer

    Science.gov (United States)

    2017-11-01

    prostate   cancer  and  other   cancers .   15. SUBJECT TERMS B7x, B7-H3, HHLA2, TMIGD2, Receptors , Immune Checkpoint, Prostate Cancer , Monoclonal...H3,  HHLA2,  TMIGD2,   Receptors ,  Immune  Checkpoint,   Prostate   Cancer ,   Monoclonal  Antibodies,  Crystal  Structure,  Immunotherapy,  T  Cells... prostate   cancer  immunotherapy.       Unlike  B7x  and  B7-­H3  whose   receptors  have  not  been  found  yet,  we  have   quickly  discovered  two

  18. Effects of LHRH and ANG II on prolactin stimulation are mediated by hypophysial AT1 receptor subtype.

    Science.gov (United States)

    Becú-Villalobos, D; Lacau-Mengido, I M; Thyssen, S M; Díaz-Torga, G S; Libertun, C

    1994-02-01

    We have used the nonpeptide angiotensin II (ANG II) receptor antagonists losartan (receptor subtype AT1) and PD-123319 (AT2) to determine the participation of ANG II receptor subtypes in luteinizing hormone-releasing hormone (LHRH)-induced prolactin release in a perifusion study using intact pituitaries in vitro. LHRH (1.85 x 10(-7) M) released prolactin consistently, whereas losartan (10(-5) M) abolished prolactin response without modifying basal prolactin or luteinizing hormone (LH) and follicle-stimulating hormone (FSH) release. PD-123319 (10(-5) M) had no effect on basal or LHRH-induced prolactin, LH, or FSH release. We also determined that the effect of ANG II on prolactin release was mediated by the same receptor subtype. In adenohypophysial cells dispersed in vitro ANG II (10(-8) M) released prolactin. Losartan (10(-7) and 10(-6) M), but not PD-123319, inhibited this effect. We conclude that in intact hypophyses of 15-day-old female rats the effect of LHRH on prolactin release is readily demonstrated. LHRH-induced prolactin release appears to be mediated by ANG II acting in a paracrine manner on AT1 receptors located on lactotrophs.

  19. 5-HT7 receptor activation: procognitive and antiamnesic effects.

    Science.gov (United States)

    Meneses, A; Perez-Garcia, G; Liy-Salmeron, G; Ponce-López, T; Lacivita, E; Leopoldo, M

    2015-02-01

    The serotonin (5-hydroxytryptamine (5-HT)) 5-HT7 receptor is localized in brain areas mediating memory; however, the role of this receptor on memory remains little explored. First, demonstrating the associative nature of Pavlovian/instrumental autoshaping (P/I-A) task, rats were exposed (three sessions) to CS-US (Pavlovian autoshaping), truly random control, free operant, and presentations of US or CS, and they were compared with rats trained-tested for one session to the P/I-A procedure. Also, effects of the 5-HT7 receptor agonist LP-211 administered intraperitoneally after training was determined on short- (1.5 h) and long-term memory 24 and 48 h) and on scopolamine-induced memory impairment and cAMP production. Autoshaping and its behavioral controls were studied. Other animals were subjected to an autoshaping training session and immediately afterwards were given (intraperitoneal) vehicle or LP-211 (0.1-10 mg/kg) and/or scopolamine (0.2 mg/kg) and tested for short-term memory (STM) and long-term memory (LTM); their brains were extracted for the cAMP ELISA immunoassay. P/I-A group produced the higher %CR. LP-211 did not affect STM; nonetheless, at 0.5 and 1.0 mg/kg, it improved LTM. The 5-HT7 receptor antagonist SB-269970 (SB; 10.0 mg/kg) alone had no effect; nevertheless, the LP-211 (1.0 mg/kg) LTM facilitation was reversed by SB. The scopolamine (0.2 mg/kg) induced-decrement in CR was accompanied by significant increased cAMP production. The scopolamine-induced decrement in CR and increments in cAMP were significantly attenuated by LP-211. Autoshaping is a reliable associative learning task whose consolidation is facilitated by the 5-HT7 receptor agonist LP-211.

  20. Proneoplastic effects of PGE2 mediated by EP4 receptor in colorectal cancer.

    LENUS (Irish Health Repository)

    Doherty, Glen A

    2009-01-01

    BACKGROUND: Prostaglandin E2 (PGE2) is the major product of Cyclooxygenase-2 (COX-2) in colorectal cancer (CRC). We aimed to assess PGE2 cell surface receptors (EP 1-4) to examine the mechanisms by which PGE2 regulates tumour progression. METHODS: Gene expression studies were performed by quantitative RT-PCR. Cell cycle was analysed by flow cytometry with cell proliferation quantified by BrdU incorporation measured by enzyme immunoassay. Immunohistochemistry was employed for expression studies on formalin fixed paraffin embedded tumour tissue. RESULTS: EP4 was the most abundant subtype of PGE2 receptor in HT-29 and HCA7 cells (which show COX-2 dependent PGE2 generation) and was consistently the most abundant transcript in human colorectal tumours (n = 8) by qRT-PCR (ANOVA, p = 0.01). G0\\/G1 cell cycle arrest was observed in HT-29 cells treated with SC-236 5 microM (selective COX-2 inhibitor) for 24 hours (p = 0.02), an effect abrogated by co-incubation with PGE2 (1 microM). G0\\/G1 arrest was also seen with a specific EP4 receptor antagonist (EP4A, L-161982) (p = 0.01). Treatment of HT-29 cells with either SC-236 or EP4A caused reduction in intracellular cAMP (ANOVA, p = 0.01). Early induction in p21WAF1\\/CIP1 expression (by qRT-PCR) was seen with EP4A treatment (mean fold increase 4.4, p = 0.04) while other genes remained unchanged. Similar induction in p21WAF1\\/CIP1 was also seen with PD153025 (1 microM), an EGFR tyrosine kinase inhibitor, suggesting EGFR transactivation by EP4 as a potential mechanism. Additive inhibition of HCA7 proliferation was observed with the combination of SC-236 and neutralising antibody to amphiregulin (AR), a soluble EGFR ligand. Concordance in COX-2 and AR localisation in human colorectal tumours was noted. CONCLUSION: COX-2 regulates cell cycle transition via EP4 receptor and altered p21WAF1\\/CIP1 expression. EGFR pathways appear important. Specific targeting of the EP4 receptor or downstream targets may offer a safer alternative

  1. Association of P2X7 gene common polymorphisms with pulmonary tuberculosis in Lur population of Iran

    Directory of Open Access Journals (Sweden)

    Ali Amiri

    2018-07-01

    Full Text Available Background: Different genetic and environmental factors are associated with susceptibility to pulmonary tuberculosis (TB in different individuals of different populations. Based on previous studies role of P2X7 gene common polymorphisms in susceptibility to pulmonary TB was associated with ethnicities. Aim: We intend to perform this study on genetic reservoir (gene pool of Lur population of western Iran. Methods: For the present case-control study, 100 unrelated pulmonary TB patients and 100 unrelated controls were enrolled through convenient sampling. TB confirmation was through smear and culture of sputum. Polymerase chain reaction with restriction fragment length polymorphism (PCR-RFLP was used for molecular assay. This study has been approved in the ethic committee of Lorestan University of Medical Sciences with registration number LUMS.REC.1396.253. Results: Among the genotypes of polymorphism 1513A/C, AA genotype was associated with susceptibility to pulmonary TB (P = .0001; OR = 4.750 whereas AC genotype was a protecting factor (P = .0001; OR = 0.192. Higher genetic reservoir of A allele was associated with more susceptibility to pulmonary TB (P = .0001; OR = 2.879 whereas C allele was a protecting factor (P = .0001; OR = 0.347. No significant result was found for −762T/C polymorphism. Conclusion: In Lur population of Iran, 1513A/C polymorphism of P2X7 is associated with susceptibility to pulmonary TB. It is suggested that bio-information banks should be established and developed in countries. Keywords: Pulmonary tuberculosis, Immunogenetics, P2X7, Population genetics

  2. Luminescence of Ce3+ at two different sites in ?-Sr2P2O7 under vacuum ultraviolet-UV and x-ray excitation

    NARCIS (Netherlands)

    Hou, D.; Han, B.; Chen, W.; Liang, H.; Su, Q.; Dorenbos, P.; Huang, Y.; Gao, Z.; Tao, Y.

    2010-01-01

    A series of Ce3+ doped ?-Sr2?2xCexNaxP2O7 phosphor compounds has been prepared using a high-temperature solid-state reaction technique. The luminescence properties under vacuum ultraviolet-UV and x-ray excitation were studied. Luminescence spectra reveal three UV-emitting peaks at about 310, 330,

  3. A tryptophan-rich motif in the human parainfluenza virus type 2 V protein is critical for the blockade of toll-like receptor 7 (TLR7)- and TLR9-dependent signaling.

    Science.gov (United States)

    Kitagawa, Yoshinori; Yamaguchi, Mayu; Zhou, Min; Komatsu, Takayuki; Nishio, Machiko; Sugiyama, Tsuyoshi; Takeuchi, Kenji; Itoh, Masae; Gotoh, Bin

    2011-05-01

    Plasmacytoid dendritic cells (pDCs) do not produce alpha interferon (IFN-α) unless viruses cause a systemic infection or overcome the first-line defense provided by conventional DCs and macrophages. We show here that even paramyxoviruses, whose infections are restricted to the respiratory tract, have a V protein able to prevent Toll-like receptor 7 (TLR7)- and TLR9-dependent IFN-α induction specific to pDCs. Mutational analysis of human parainfluenza virus type 2 demonstrates that the second Trp residue of the Trp-rich motif (Trp-X(3)-Trp-X(9)-Trp) in the C-terminal domain unique to V, a determinant for IRF7 binding, is critical for the blockade of TLR7/9-dependent signaling.

  4. Crystallization-mediated amorphous Cu_xO (x = 1, 2)/crystalline CuI p–p type heterojunctions with visible light enhanced and ultraviolet light restrained photocatalytic dye degradation performance

    International Nuclear Information System (INIS)

    Wang, Hongli; Cai, Yun; Zhou, Jian; Fang, Jun; Yang, Yang

    2017-01-01

    Highlights: • Cu_xO(x = 1, 2)/CuI p–p type heterojunctions were facilely constructed via crystallization-mediated approaches. • Cu_xO/CuI heterojunctions exhibit effective visible-light-driven photocatalytic activity for dye degradation. • The Cu_xO/CuI interface can enhance the spatial separation of the photogenerated electron–hole pairs. • This work represents a critical step for mass production of functional semiconductor heterojunctions in a mild manner. - Abstract: We report simple and cost-effective fabrication of amorphous Cu_xO (x = 1, 2)/crystalline CuI p–p type heterojunctions based on crystallization-mediated approaches including antisolvent crystallization and crystal reconstruction. Starting from CuI acetonitrile solution, large crystals in commercial CuI can be easily converted to aggregates consisting of small particles by the crystallization processes while the spontaneous oxidation of CuI by atmospheric/dissolved oxygen can induce the formation of trace Cu_xO on CuI surface. As a proof of concept, the as-fabricated Cu_xO/CuI heterojunctions exhibit effective photocatalytic activity towards the degradation of methyl blue and other organic pollutants under visible light irradiation, although the wide band-gap semiconductor CuI is insensible to visible light. Unexpectedly, the Cu_xO/CuI heterojunctions exhibit restrained photocatalytic activity when ultraviolet light is applied in addition to the visible. It is suggested that the Cu_xO/CuI interface can enhance the spatial separation of the electron–hole pairs with the excitation of Cu_xO under visible light and prolong the lifetime of photogenerated charges with high redox ability. The present work represents a critically important step in advancing the crystallization technique for potential mass production of semiconductor heterojunctions in a mild manner.

  5. NADE, a p75NTR-associated cell death executor, is involved in signal transduction mediated by the common neurotrophin receptor p75NTR.

    Science.gov (United States)

    Mukai, J; Hachiya, T; Shoji-Hoshino, S; Kimura, M T; Nadano, D; Suvanto, P; Hanaoka, T; Li, Y; Irie, S; Greene, L A; Sato, T A

    2000-06-09

    The low affinity neurotrophin receptor p75NTR can mediate cell survival as well as cell death of neural cells by NGF and other neurotrophins. To elucidate p75NTR-mediated signal transduction, we screened p75NTR-associated proteins by a yeast two-hybrid system. We identified one positive clone and named NADE (p75NTR-associated cell death executor). Mouse NADE has marked homology to the human HGR74 protein. NADE specifically binds to the cell-death domain of p75NTR. Co-expression of NADE and p75NTR induced caspase-2 and caspase-3 activities and the fragmentation of nuclear DNA in 293T cells. However, in the absence of p75NTR, NADE failed to induce apoptosis, suggesting that NADE expression is necessary but insufficient for p75NTR-mediated apoptosis. Furthermore, p75NTR/NADE-induced cell death was dependent on NGF but not BDNF, NT-3, or NT-4/5, and the recruitment of NADE to p75NTR (intracellular domain) was dose-dependent. We obtained similar results from PC12 cells, nnr5 cells, and oligodendrocytes. Taken together, NADE is the first signaling adaptor molecule identified in the involvement of p75NTR-mediated apoptosis induced by NGF, and it may play an important role in the pathogenesis of neurogenetic diseases.

  6. The overexpressed human 46-kDa mannose 6-phosphate receptor mediates endocytosis and sorting of β-glucuronidase

    International Nuclear Information System (INIS)

    Watanabe, H.; Grubb, J.H.; Sly, W.S.

    1990-01-01

    The authors studied the function of the human small (46-kDa) mannose 6-phosphate receptor (SMPR) in transfected mouse L cells that do not express the larger insulin-like growth factor II/mannose 6-phosphate receptor. Cells overexpressing human SMPR were studied for enzyme binding to cell surface receptors, for binding to intracellular receptors in permeabilized cells, and for receptor-mediated endocytosis of recombinant human β-glucuronidase. Specific binding to human SMPR in permeabilized cells showed a pH optimum between pH 6.0 and pH 6.5. Binding was significant in the present of EDTA but was enhanced by added divalent cations. Up to 2.3% of the total functional receptor could be detected on the cell surface by enzyme binding. They present experiments showing that at very high levels of overexpression, and at pH 6.5, human SMPR mediated the endocytosis of β-glucuronidase. At pH 7.5, the rate of endocytosis was only 14% the rate seen at pH 6.5. Cells overexpressing human SMPR also showed reduced secretion of newly synthesized β-glucuronidase when compared to cells transfected with vector only, suggesting that overexpressed human SMPR can participate in sorting of newly synthesized β-glucuronidase and partially correct the sorting defect in mouse L cells that do not express the insulin-like growth factor II/mannose 6-phosphate receptor

  7. Adenosine A2A receptor-dependent proliferation of pulmonary endothelial cells is mediated through calcium mobilization, PI3-kinase and ERK1/2 pathways

    International Nuclear Information System (INIS)

    Ahmad, Aftab; Schaack, Jerome B.; White, Carl W.; Ahmad, Shama

    2013-01-01

    Highlights: •A 2A receptor-induced pulmonary endothelial growth is mediated by PI3K and ERK1/2. •Cytosolic calcium mobilization is also critical for pulmonary endothelial growth. •Effectors of A 2A receptor, like tyrosine kinases and cAMP increase PI3K/Akt signaling. •Activation of A 2A receptor can contribute to vascular remodeling. -- Abstract: Hypoxia and HIF-2α-dependent A 2A receptor expression and activation increase proliferation of human lung microvascular endothelial cells (HLMVECs). This study was undertaken to investigate the signaling mechanisms that mediate the proliferative effects of A 2A receptor. A 2A receptor-mediated proliferation of HLMVECs was inhibited by intracellular calcium chelation, and by specific inhibitors of ERK1/2 and PI3-kinase (PI3K). The adenosine A 2A receptor agonist CGS21680 caused intracellular calcium mobilization in controls and, to a greater extent, in A 2A receptor-overexpressing HLMVECs. Adenoviral-mediated A 2A receptor overexpression as well as receptor activation by CGS21680 caused increased PI3K activity and Akt phosphorylation. Cells overexpressing A 2A receptor also manifested enhanced ERK1/2 phosphorylation upon CGS21680 treatment. A 2A receptor activation also caused enhanced cAMP production. Likewise, treatment with 8Br-cAMP increased PI3K activity. Hence A 2A receptor-mediated cAMP production and PI3K and Akt phosphorylation are potential mediators of the A 2A -mediated proliferative response of HLMVECs. Cytosolic calcium mobilization and ERK1/2 phosphorylation are other critical effectors of HLMVEC proliferation and growth. These studies underscore the importance of adenosine A 2A receptor in activation of survival and proliferative pathways in pulmonary endothelial cells that are mediated through PI3K/Akt and ERK1/2 pathways

  8. Structural Basis of Competitive Recognition of p53 and MDM2 by HAUSP/USP7: Implications for the Regulation of the p53-MDM2 Pathway.

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available Herpesvirus-associated ubiquitin-specific protease (HAUSP, also known as USP7, a deubiquitylating enzyme of the ubiquitin-specific processing protease family, specifically deubiquitylates both p53 and MDM2, hence playing an important yet enigmatic role in the p53-MDM2 pathway. Here we demonstrate that both p53 and MDM2 specifically recognize the N-terminal tumor necrosis factor-receptor associated factor (TRAF-like domain of HAUSP in a mutually exclusive manner. HAUSP preferentially forms a stable HAUSP-MDM2 complex even in the presence of excess p53. The HAUSP-binding elements were mapped to a peptide fragment in the carboxy-terminus of p53 and to a short-peptide region preceding the acidic domain of MDM2. The crystal structures of the HAUSP TRAF-like domain in complex with p53 and MDM2 peptides, determined at 2.3-A and 1.7-A resolutions, respectively, reveal that the MDM2 peptide recognizes the same surface groove in HAUSP as that recognized by p53 but mediates more extensive interactions. Structural comparison led to the identification of a consensus peptide-recognition sequence by HAUSP. These results, together with the structure of a combined substrate-binding-and-deubiquitylation domain of HAUSP, provide important insights into regulation of the p53-MDM2 pathway by HAUSP.

  9. Hyperoxia-induced p47phox activation and ROS generation is mediated through S1P transporter Spns2, and S1P/S1P1&2 signaling axis in lung endothelium.

    Science.gov (United States)

    Harijith, Anantha; Pendyala, Srikanth; Ebenezer, David L; Ha, Alison W; Fu, Panfeng; Wang, Yue-Ting; Ma, Ke; Toth, Peter T; Berdyshev, Evgeny V; Kanteti, Prasad; Natarajan, Viswanathan

    2016-08-01

    Hyperoxia-induced lung injury adversely affects ICU patients and neonates on ventilator assisted breathing. The underlying culprit appears to be reactive oxygen species (ROS)-induced lung damage. The major contributor of hyperoxia-induced ROS is activation of the multiprotein enzyme complex NADPH oxidase. Sphingosine-1-phosphate (S1P) signaling is known to be involved in hyperoxia-mediated ROS generation; however, the mechanism(s) of S1P-induced NADPH oxidase activation is unclear. Here, we investigated various steps in the S1P signaling pathway mediating ROS production in response to hyperoxia in lung endothelium. Of the two closely related sphingosine kinases (SphKs)1 and 2, which synthesize S1P from sphingosine, only Sphk1(-/-) mice conferred protection against hyperoxia-induced lung injury. S1P is metabolized predominantly by S1P lyase and partial deletion of Sgpl1 (Sgpl1(+/-)) in mice accentuated lung injury. Hyperoxia stimulated S1P accumulation in human lung microvascular endothelial cells (HLMVECs), and downregulation of S1P transporter spinster homolog 2 (Spns2) or S1P receptors S1P1&2, but not S1P3, using specific siRNA attenuated hyperoxia-induced p47(phox) translocation to cell periphery and ROS generation in HLMVECs. These results suggest a role for Spns2 and S1P1&2 in hyperoxia-mediated ROS generation. In addition, p47(phox) (phox:phagocyte oxidase) activation and ROS generation was also reduced by PF543, a specific SphK1 inhibitor in HLMVECs. Our data indicate a novel role for Spns2 and S1P1&2 in the activation of p47(phox) and production of ROS involved in hyperoxia-mediated lung injury in neonatal and adult mice. Copyright © 2016 the American Physiological Society.

  10. MBL, P2X7, and SLC11A1 gene polymorphisms in patients with oropharyngeal tularemia.

    Science.gov (United States)

    Somuk, Battal Tahsin; Koc, Sema; Ates, Omer; Göktas, Göksel; Soyalic, Harun; Uysal, Ismail Onder; Gurbuzler, Levent; Sapmaz, Emrah; Sezer, Saime; Eyibilen, Ahmet

    2016-11-01

    A significant association was found of oropharyngeal tularemia with SLC11A1 allele polymorphism (INT4 G/C) and MBL2 C + 4T (P/Q). These results indicate C allele and Q allele might be a risk factor for the development of oropharyngeal tularemia. This study aimed to investigate the relationship of SLC11A1, MBL, and P2X 7 gene polymorphism with oropharyngeal tularemia. The study included totally 120 patients who were diagnosed with oropharyngeal tularemia. Frequencies of polymorphisms in the following genes were analyzed both in the patient and control groups in the study: SLC11A1 (5'(GT) n Allele 2/3, Int4 G/C, 3' UTR, D543N G/A), MBL (MBL2 C + 4T (P/Q), and P2X 7 (-762 C/T and 1513 A/C). Among all polymorphisms that were investigated in this study, SLC11A1 gene showed a significance in the distriburtion of polymorphism allelle frequency at the INT4 region. Frequency of C allele was 54 (28%) in patients with oropharyngeal tularemia, and 31 (13%) in the control group (p = 0.006 and OR = 1.96 (1.21-3.20)). An association was detected between MBL2 C + 4T (P/Q) gene polymorphism and oropharyngeal tularemia (p tularemia in this study (p > 0.05).

  11. Molecular mechanisms of platelet P2Y(12) receptor regulation.

    Science.gov (United States)

    Cunningham, Margaret R; Nisar, Shaista P; Mundell, Stuart J

    2013-02-01

    Platelets are critical for haemostasis, however inappropriate activation can lead to the development of arterial thrombosis, which can result in heart attack and stroke. ADP is a key platelet agonist that exerts its actions via stimulation of two surface GPCRs (G-protein-coupled receptors), P2Y(1) and P2Y(12). Similar to most GPCRs, P2Y receptor activity is tightly regulated by a number of complex mechanisms including receptor desensitization, internalization and recycling. In the present article, we review the molecular mechanisms that underlie P2Y(1) and P2Y(12) receptor regulation, with particular emphasis on the structural motifs within the P2Y(12) receptor, which are required to maintain regulatory protein interaction. The implications of these findings for platelet responsiveness are also discussed.

  12. In vitro binding and receptor-mediated activity of terlipressin at vasopressin receptors V1 and V2.

    Science.gov (United States)

    Jamil, Khurram; Pappas, Stephen Chris; Devarakonda, Krishna R

    2018-01-01

    Terlipressin, a synthetic, systemic vasoconstrictor with selective activity at vasopressin-1 (V 1 ) receptors, is a pro-drug for the endogenous/natural porcine hormone [Lys 8 ]-vasopressin (LVP). We investigated binding and receptor-mediated cellular activities of terlipressin, LVP, and endogenous human hormone [Arg 8 ]-vasopressin (AVP) at V 1 and vasopressin-2 (V 2 ) receptors. Cell membrane homogenates of Chinese hamster ovary cells expressing human V 1 and V 2 receptors were used in competitive binding assays to measure receptor-binding activity. These cells were used in functional assays to measure receptor-mediated cellular activity of terlipressin, LVP, and AVP. Binding was measured by [ 3 H]AVP counts, and the activity was measured by fluorometric detection of intracellular calcium mobilization (V 1 ) and cyclic adenosine monophosphate (V 2 ). Binding potency at V 1 and V 2 was AVP>LVP>terlipressin. LVP and terlipressin had approximately sixfold higher affinity for V 1 than for V 2 . Cellular activity potency was also AVP>LVP>terlipressin. Terlipressin was a partial agonist at V 1 and a full agonist at V 2 ; LVP was a full agonist at both V 1 and V 2 . The in vivo response to terlipressin is likely due to the partial V 1 agonist activity of terlipressin and full V 1 agonist activity of its metabolite, LVP. These results provide supportive evidence for previous findings and further establish terlipressin pharmacology for vasopressin receptors.

  13. The inhibition effect of 2,3,7,8-tetrachlorinated dibenzo-p-dioxin-induced aryl hydrocarbon receptor activation in human hepatoma cells with the treatment of cadmium chloride

    International Nuclear Information System (INIS)

    Chao, How-Ran; Tsou, Tsui-Chun; Chen, Hung-Ta; Chang, Eddy Essen; Tsai, Feng-Yuan; Lin, Ding-Yan; Chen, Fu-An; Wang, Ya-Fen

    2009-01-01

    Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), considered as endocrine disruptors, tend to accumulate in fatty tissues. Dioxin-responsive element chemical activated luciferase gene expression assay (DRE-luciferase assay) has been recognized as a semi-quantitative method for screening dioxins for its fast and low-cost as compared with HRGC/HRMS. However, some problems with the bioassay, including specificity, detection variation resulted from different cleanup strategies, and uncertainty of false-negative or false-positive results, remain to be overcome. Cadmium is a prevalent environmental contaminant around the world. This study was aimed to examine the effects of cadmium on the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced activation of aryl hydrocarbon receptor (AhR)-mediated gene expression in human hepatoma cells (Huh7-DRE-Luc cells and Huh7 cells). Ethoxyresorufin-O-deethylase (EROD) and DRE-luciferase assay were employed to determine the enzyme activity of cytochrome P450 1A1 (CYP1A1) and activation of AhR, respectively. The results showed that Cd 2+ levels significantly inhibited the induction of TCDD-induced CYP1A1 and DRE luciferase activation in hepatoma cells. The 50% inhibited concentrations (IC 50 ) of CdCl 2 were 0.414 μM (95% confidence interval (C.I.): 0.230-0.602 μM) in Huh7-DRE-Luc cells and 23.2 μM (95% C.I.: 21.7-25.4 μM) in Huh7 cells. Accordingly, prevention of interference with non-dioxin-like compounds in a DRE-luciferase assay is of great importance in an extensive cleanup procedure.

  14. Mediator and p300/CBP-Steroid Receptor Coactivator Complexes Have Distinct Roles, but Function Synergistically, during Estrogen Receptor α-Dependent Transcription with Chromatin Templates

    OpenAIRE

    Acevedo, Mari Luz; Kraus, W. Lee

    2003-01-01

    Ligand-dependent transcriptional activation by nuclear receptors involves the recruitment of various coactivators to the promoters of hormone-regulated genes assembled into chromatin. Nuclear receptor coactivators include histone acetyltransferase complexes, such as p300/CBP-steroid receptor coactivator (SRC), as well as the multisubunit mediator complexes (“Mediator”), which may help recruit RNA polymerase II to the promoter. We have used a biochemical approach, including an in vitro chromat...

  15. Posttraumatic Propofol Neurotoxicity Is Mediated via the Pro-Brain-Derived Neurotrophic Factor-p75 Neurotrophin Receptor Pathway in Adult Mice.

    Science.gov (United States)

    Sebastiani, Anne; Granold, Matthias; Ditter, Anja; Sebastiani, Philipp; Gölz, Christina; Pöttker, Bruno; Luh, Clara; Schaible, Eva-Verena; Radyushkin, Konstantin; Timaru-Kast, Ralph; Werner, Christian; Schäfer, Michael K; Engelhard, Kristin; Moosmann, Bernd; Thal, Serge C

    2016-02-01

    The gamma-aminobutyric acid modulator propofol induces neuronal cell death in healthy immature brains by unbalancing neurotrophin homeostasis via p75 neurotrophin receptor signaling. In adulthood, p75 neurotrophin receptor becomes down-regulated and propofol loses its neurotoxic effect. However, acute brain lesions, such as traumatic brain injury, reactivate developmental-like programs and increase p75 neurotrophin receptor expression, probably to foster reparative processes, which in turn could render the brain sensitive to propofol-mediated neurotoxicity. This study investigates the influence of delayed single-bolus propofol applications at the peak of p75 neurotrophin receptor expression after experimental traumatic brain injury in adult mice. Randomized laboratory animal study. University research laboratory. Adult C57BL/6N and nerve growth factor receptor-deficient mice. Sedation by IV propofol bolus application delayed after controlled cortical impact injury. Propofol sedation at 24 hours after traumatic brain injury increased lesion volume, enhanced calpain-induced αII-spectrin cleavage, and increased cell death in perilesional tissue. Thirty-day postinjury motor function determined by CatWalk (Noldus Information Technology, Wageningen, The Netherlands) gait analysis was significantly impaired in propofol-sedated animals. Propofol enhanced pro-brain-derived neurotrophic factor/brain-derived neurotrophic factor ratio, which aggravates p75 neurotrophin receptor-mediated cell death. Propofol toxicity was abolished both by pharmacologic inhibition of the cell death domain of the p75 neurotrophin receptor (TAT-Pep5) and in mice lacking the extracellular neurotrophin binding site of p75 neurotrophin receptor. This study provides first evidence that propofol sedation after acute brain lesions can have a deleterious impact and implicates a role for the pro-brain-derived neurotrophic factor-p75 neurotrophin receptor pathway. This observation is important as sedation

  16. Phosphorylated hepatocyte growth factor receptor/c-Met is associated with tumor growth and prognosis in patients with bladder cancer: correlation with matrix metalloproteinase-2 and -7 and E-cadherin.

    Science.gov (United States)

    Miyata, Yasuyoshi; Sagara, Yuji; Kanda, Shigeru; Hayashi, Tomayoshi; Kanetake, Hiroshi

    2009-04-01

    Hepatocyte growth factor receptor/c-Met is associated with malignant aggressiveness and survival in various cancers including bladder cancer. Although phosphorylation of hepatocyte growth factor receptor/c-Met is essential for its function, the pathologic significance of phosphorylated hepatocyte growth factor receptor/c-Met in bladder cancer remains elusive. We investigated the clinical significance of its expression, and its correlation with cancer cell progression-related molecules. The expression levels of 2 tyrosine residues of hepatocyte growth factor receptor/c-Met (pY1234/1235 and pY1349) were examined immunohistochemically in 133 specimens with nonmetastatic bladder cancer. We also investigated their correlation with matrix metalloproteinase-1, -2, -7, and -14; urokinase-type plasminogen activator; E-cadherin; CD44 standard, variant 3, and variant 6; and vascular endothelial growth factor. Expression of phosphorylated hepatocyte growth factor receptor/c-Met was detected in cancer cells, but was rare in normal urothelial cells. Although hepatocyte growth factor receptor/c-Met, pY1234/1235 hepatocyte growth factor receptor/c-Met, and pY1349 hepatocyte growth factor receptor/c-Met were associated with pT stage, multivariate analysis identified pY1349 hepatocyte growth factor receptor/c-met expression only as a significant factor for high pT stage. Expression of pY1349 hepatocyte growth factor receptor/c-Met was a marker of metastasis and (P = .001) and cause-specific survival (P = .003). Expressions of matrix metalloproteinase-2, matrix metalloproteinase-7, and E-cadherin correlated with pY1349 hepatocyte growth factor receptor/c-Met expression. Our results demonstrated that pY1349 hepatocyte growth factor receptor/c-Met plays an important role in tumor development, and its expression is a significant predictor of metastasis and survival of patients with bladder cancer. The results suggest that these activities are mediated, at least in part, by matrix

  17. Equivalent molecular mass of cytosolic and nuclear forms of Ah receptor from Hepa-1 cells determined by photoaffinity labeling with 2,3,7,8-[3H]tetrachlorodibenzo-p-dioxin

    International Nuclear Information System (INIS)

    Prokipcak, R.D.; Okey, A.B.

    1990-01-01

    The structure of the Ah receptor previously has been extensively characterized by reversible binding of the high affinity ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin. We report the use of [ 3 H]2,3,7,8-tetrachlorodibenzo-p-dioxin as a photoaffinity ligand for Ah receptor from the mouse hepatoma cell line Hepa-1c1c9. Both cytosolic and nuclear forms of Ah receptor could be specifically photoaffinity-labeled, which allowed determination of molecular mass for the two forms under denaturing conditions. After analysis by fluorography of polyacrylamide gels run in the presence of sodium dodecyl sulfate, molecular mass for the cytosolic form of Ah receptor was estimated at 92,000 +/- 4,300 and that for the nuclear form was estimated at 93,500 +/- 3,400. Receptor in mixture of cytosol and nuclear extract (each labeled separately with [ 3 H]2,3,7,8-tetrachlorodibenzo-p-dioxin) migrated as a single band. These results are consistent with the presence of a common ligand-binding subunit of identical molecular mass in both cytosolic and nuclear complexes

  18. Crystallization-mediated amorphous Cu{sub x}O (x = 1, 2)/crystalline CuI p–p type heterojunctions with visible light enhanced and ultraviolet light restrained photocatalytic dye degradation performance

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hongli; Cai, Yun; Zhou, Jian; Fang, Jun, E-mail: fangjun@njtech.edu.cn; Yang, Yang, E-mail: yangy@njtech.edu.cn

    2017-04-30

    Highlights: • Cu{sub x}O(x = 1, 2)/CuI p–p type heterojunctions were facilely constructed via crystallization-mediated approaches. • Cu{sub x}O/CuI heterojunctions exhibit effective visible-light-driven photocatalytic activity for dye degradation. • The Cu{sub x}O/CuI interface can enhance the spatial separation of the photogenerated electron–hole pairs. • This work represents a critical step for mass production of functional semiconductor heterojunctions in a mild manner. - Abstract: We report simple and cost-effective fabrication of amorphous Cu{sub x}O (x = 1, 2)/crystalline CuI p–p type heterojunctions based on crystallization-mediated approaches including antisolvent crystallization and crystal reconstruction. Starting from CuI acetonitrile solution, large crystals in commercial CuI can be easily converted to aggregates consisting of small particles by the crystallization processes while the spontaneous oxidation of CuI by atmospheric/dissolved oxygen can induce the formation of trace Cu{sub x}O on CuI surface. As a proof of concept, the as-fabricated Cu{sub x}O/CuI heterojunctions exhibit effective photocatalytic activity towards the degradation of methyl blue and other organic pollutants under visible light irradiation, although the wide band-gap semiconductor CuI is insensible to visible light. Unexpectedly, the Cu{sub x}O/CuI heterojunctions exhibit restrained photocatalytic activity when ultraviolet light is applied in addition to the visible. It is suggested that the Cu{sub x}O/CuI interface can enhance the spatial separation of the electron–hole pairs with the excitation of Cu{sub x}O under visible light and prolong the lifetime of photogenerated charges with high redox ability. The present work represents a critically important step in advancing the crystallization technique for potential mass production of semiconductor heterojunctions in a mild manner.

  19. Sphingosine 1-phosphate receptor activation enhances BMP-2-induced osteoblast differentiation

    International Nuclear Information System (INIS)

    Sato, Chieri; Iwasaki, Tsuyoshi; Kitano, Sachie; Tsunemi, Sachi; Sano, Hajime

    2012-01-01

    Highlights: ► We investigated the role of S1P signaling for osteoblast differentiation. ► Both S1P and FTY enhanced BMP-2-stimulated osteoblast differentiation by C2C12 cells. ► S1P signaling enhanced BMP-2-stimulated Smad and ERK phosphorylation by C2C12 cells. ► MEK/ERK signaling is a pathway underlying S1P signaling for osteoblast differentiation. -- Abstract: We previously demonstrated that sphingosine 1-phosphate (S1P) receptor-mediated signaling induced proliferation and prostaglandin productions by synovial cells from rheumatoid arthritis (RA) patients. In the present study we investigated the role of S1P receptor-mediated signaling for osteoblast differentiation. We investigated osteoblast differentiation using C2C12 myoblasts, a cell line derived from murine satellite cells. Osteoblast differentiation was induced by the treatment of bone morphogenic protein (BMP)-2 in the presence or absence of either S1P or FTY720 (FTY), a high-affinity agonist of S1P receptors. Osteoblast differentiation was determined by osteoblast-specific transcription factor, Runx2 mRNA expression, alkaline phosphatase (ALP) activity and osteocalcin production by the cells. Smad1/5/8 and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation was examined by Western blotting. Osteocalcin production by C2C12 cells were determined by ELISA. Runx2 expression and ALP activity by BMP-2-stimulated C2C12 cells were enhanced by addition of either S1P or FTY. Both S1P and FTY enhanced BMP-2-induced ERK1/2 and Smad1/5/8 phosphorylation. The effect of FTY was stronger than that of S1P. S1P receptor-mediated signaling on osteoblast differentiation was inhibited by addition of mitogen-activated protein kinase/ERK kinase (MEK) 1/2 inhibitor, indicating that the S1P receptor-mediated MEK1/2-ERK1/2 signaling pathway enhanced BMP-2-Smad signaling. These results indicate that S1P receptor-mediated signaling plays a crucial role for osteoblast differentiation.

  20. Dynamics of receptor-operated Ca2+ Currents Through TRPC Channels Controlled via the PI(4,5P2-PLC Signaling Pathway

    Directory of Open Access Journals (Sweden)

    Masayuki X Mori

    2015-02-01

    Full Text Available Transient receptor potential canonical (TRPC channels are Ca2+-permeable, nonselective cation channels that carry receptor-operated Ca2+ currents (ROCs triggered by receptor-induced, phospholipase C (PLC-catalyzed hydrolysis of phosphatidylinositol 4,5-bisphosphate (PI(4,5P2. Within the vasculature, TRPC channel ROCs contribute to smooth muscle cell depolarization, vasoconstriction and vascular remodeling. However, TRPC channel ROCs exhibit a variable response to receptor-stimulation, and the regulatory mechanisms governing TRPC channel activity remain obscure. The variability of ROCs may be explained by their complex regulation by PI(4,5P2 and its metabolites, which differentially affect TRPC channel activity. To resolve the complex regulation of ROCs, the use of voltage-sensing phosphoinositide phosphatases and model simulation have helped to reveal the time-dependent contribution of PI(4,5P2 and the possible role of PI(4,5P2 in the regulation of ROCs. These approaches may provide unprecedented insight into the dynamics of PI(4,5P2 regulation of TRPC channels and the fundamental mechanisms underlying transmembrane ion flow. Within that context, we summarize the regulation of TRPC channels and their coupling to receptor-mediated signaling, as well as the application of voltage-sensing phosphoinositide phosphatases to this research. We also discuss the controversial bidirectional effects of PI(4,5P2 using a model simulation that could explain the complicated effects of PI(4,5P2 on different ROCs.

  1. Dynamics of receptor-operated Ca(2+) currents through TRPC channels controlled via the PI(4,5)P2-PLC signaling pathway.

    Science.gov (United States)

    Mori, Masayuki X; Itsuki, Kyohei; Hase, Hideharu; Sawamura, Seishiro; Kurokawa, Tatsuki; Mori, Yasuo; Inoue, Ryuji

    2015-01-01

    Transient receptor potential canonical (TRPC) channels are Ca(2+)-permeable, nonselective cation channels that carry receptor-operated Ca(2+) currents (ROCs) triggered by receptor-induced, phospholipase C (PLC)-catalyzed hydrolysis of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. Within the vasculature, TRPC channel ROCs contribute to smooth muscle cell depolarization, vasoconstriction, and vascular remodeling. However, TRPC channel ROCs exhibit a variable response to receptor-stimulation, and the regulatory mechanisms governing TRPC channel activity remain obscure. The variability of ROCs may be explained by their complex regulation by PI(4,5)P2 and its metabolites, which differentially affect TRPC channel activity. To resolve the complex regulation of ROCs, the use of voltage-sensing phosphoinositide phosphatases and model simulation have helped to reveal the time-dependent contribution of PI(4,5)P2 and the possible role of PI(4,5)P2 in the regulation of ROCs. These approaches may provide unprecedented insight into the dynamics of PI(4,5)P2 regulation of TRPC channels and the fundamental mechanisms underlying transmembrane ion flow. Within that context, we summarize the regulation of TRPC channels and their coupling to receptor-mediated signaling, as well as the application of voltage-sensing phosphoinositide phosphatases to this research. We also discuss the controversial bidirectional effects of PI(4,5)P2 using a model simulation that could explain the complicated effects of PI(4,5)P2 on different ROCs.

  2. Magnetic-entropy change in Mn1.1Fe0.9P0.7As0.3-xGe x

    International Nuclear Information System (INIS)

    Tegus, O.; Fuquan, B.; Dagula, W.; Zhang, L.; Brueck, E.; Si, P.Z.; Boer, F.R. de; Buschow, K.H.J.

    2005-01-01

    We have studied the magnetic properties and magnetic-entropy changes of Mn 1.1 Fe 0.9 P 0.7 As 0.3-x Ge x compounds with x = 0, 0.05, 0.1, 0.15 and 0.3. X-ray diffraction (XRD) study shows all the compounds crystallize in the Fe 2 P-type structure. Magnetic measurements show that the Curie temperature increases from 150 K for Mn 1.1 Fe 0.9 P 0.7 As 0.3 to 380 K for Mn 1.1 Fe 0.9 P 0.7 Ge 0.3 . A field-induced first-order magnetic phase transition is observed above the Curie temperature for the compounds with x up to 0.15. There exists an optimal composition in which the first-order phase transition is the sharpest. The optimal composition for this system is x = 0.1. The maximal magnetic-entropy change derived from the magnetization data is about 40 J/(kg K) for a field change from 0 to 3 T

  3. Neurotrophin Receptor p75NTR Regulates Immune Function of Plasmacytoid Dendritic Cells.

    Science.gov (United States)

    Bandoła, Joanna; Richter, Cornelia; Ryser, Martin; Jamal, Arshad; Ashton, Michelle P; von Bonin, Malte; Kuhn, Matthias; Dorschner, Benjamin; Alexopoulou, Dimitra; Navratiel, Katrin; Roeder, Ingo; Dahl, Andreas; Hedrich, Christian M; Bonifacio, Ezio; Brenner, Sebastian; Thieme, Sebastian

    2017-01-01

    Plasmacytoid dendritic cells (pDCs) regulate innate and adaptive immunity. Neurotrophins and their receptors control the function of neuronal tissue. In addition, they have been demonstrated to be part of the immune response but little is known about the effector immune cells involved. We report, for the first time, the expression and immune-regulatory function of the low affinity neurotrophin receptor p75 neurotrophin receptor (p75NTR) by the antigen-presenting pDCs, mediated by toll-like receptor (TLR) 9 activation and differential phosphorylation of interferon regulatory factor 3 and 7. The modulation of p75NTR on pDCs significantly influences disease progression of asthma in an ovalbumin-induced mouse model mediated by the TLR9 signaling pathway. p75NTR activation of pDCs from patients with asthma increased allergen-specific T cell proliferation and cytokine secretion in nerve growth factor concentration-dependent manner. Further, p75NTR activation of pDCs delayed the onset of autoimmune diabetes in RIP-CD80GP mice and aggravated graft-versus-host disease in a xenotransplantation model. Thus, p75NTR signaling on pDCs constitutes a new and critical mechanism connecting neurotrophin signaling and immune response regulation with great therapeutic potential for a variety of immune disorders.

  4. Neurotrophin Receptor p75NTR Regulates Immune Function of Plasmacytoid Dendritic Cells

    Directory of Open Access Journals (Sweden)

    Joanna Bandoła

    2017-08-01

    Full Text Available Plasmacytoid dendritic cells (pDCs regulate innate and adaptive immunity. Neurotrophins and their receptors control the function of neuronal tissue. In addition, they have been demonstrated to be part of the immune response but little is known about the effector immune cells involved. We report, for the first time, the expression and immune-regulatory function of the low affinity neurotrophin receptor p75 neurotrophin receptor (p75NTR by the antigen-presenting pDCs, mediated by toll-like receptor (TLR 9 activation and differential phosphorylation of interferon regulatory factor 3 and 7. The modulation of p75NTR on pDCs significantly influences disease progression of asthma in an ovalbumin-induced mouse model mediated by the TLR9 signaling pathway. p75NTR activation of pDCs from patients with asthma increased allergen-specific T cell proliferation and cytokine secretion in nerve growth factor concentration-dependent manner. Further, p75NTR activation of pDCs delayed the onset of autoimmune diabetes in RIP-CD80GP mice and aggravated graft-versus-host disease in a xenotransplantation model. Thus, p75NTR signaling on pDCs constitutes a new and critical mechanism connecting neurotrophin signaling and immune response regulation with great therapeutic potential for a variety of immune disorders.

  5. Arrestin scaffolds NHERF1 to the P2Y12 receptor to regulate receptor internalization.

    Science.gov (United States)

    Nisar, Shaista P; Cunningham, Margaret; Saxena, Kunal; Pope, Robert J; Kelly, Eamonn; Mundell, Stuart J

    2012-07-13

    We have recently shown in a patient with mild bleeding that the PDZ-binding motif of the platelet G protein-coupled P2Y(12) receptor (P2Y(12)R) is required for effective receptor traffic in human platelets. In this study we show for the first time that the PDZ motif-binding protein NHERF1 exerts a major role in potentiating G protein-coupled receptor (GPCR) internalization. NHERF1 interacts with the C-tail of the P2Y(12)R and unlike many other GPCRs, NHERF1 interaction is required for effective P2Y(12)R internalization. In vitro and prior to agonist stimulation P2Y(12)R/NHERF1 interaction requires the intact PDZ binding motif of this receptor. Interestingly on receptor stimulation NHERF1 no longer interacts directly with the receptor but instead binds to the receptor via the endocytic scaffolding protein arrestin. These findings suggest a novel model by which arrestin can serve as an adaptor to promote NHERF1 interaction with a GPCR to facilitate effective NHERF1-dependent receptor internalization.

  6. Haemolysis induced by α-toxin from Staphylococcus aureus requires P2X receptor activation

    DEFF Research Database (Denmark)

    Skals, Marianne Gerberg; Leipziger, Jens Georg; Prætorius, Helle

    2011-01-01

    Recently, it was documented that α-haemolysin (HlyA) from Escherichia coli uses erythrocyte P2 receptors cause lysis. This finding was surprising as it appeared firmly established that HlyA-dependent pore formation per se is sufficient for full cell lysis. We discovered that HlyA induced a sequen...

  7. Differential modulation of expression of nuclear receptor mediated genes by tris(2-butoxyethyl) phosphate (TBOEP) on early life stages of zebrafish (Danio rerio)

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Zhiyuan, E-mail: zhiyuan_nju@163.com [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China); Yu, Yijun, E-mail: yjun.yu@gmail.com [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China); Tang, Song [School of Environment and Sustainability, University of Saskatchewan, Saskatoon, SK S7N 5B3 (Canada); Liu, Hongling, E-mail: hlliu@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China); Su, Guanyong; Xie, Yuwei [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China); Giesy, John P. [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China); Toxicology Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3 (Canada); Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, SK S7N 5B3 (Canada); Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region (Hong Kong); Hecker, Markus [School of Environment and Sustainability, University of Saskatchewan, Saskatoon, SK S7N 5B3 (Canada); Toxicology Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3 (Canada); Yu, Hongxia [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China)

    2015-12-15

    Highlights: • Effects of TBOEP on expression of genes of several nuclear hormone receptors and their relationship with adverse effect pathways in zebrafish. • TBOEP was neither an agonist nor antagonist of AR or AhR as determined by use of in vitro mammalian cell-based receptor transactivation assays. • Modulation of ER- and MR-dependent pathways allowed for development of feasible receptor-mediated, critical mechanisms of toxic action. - Abstract: As one substitute for phased-out brominated flame retardants (BFRs), tris(2-butoxyethyl) phosphate (TBOEP) is frequently detected in aquatic organisms. However, knowledge about endocrine disrupting mechanisms associated with nuclear receptors caused by TBOEP remained restricted to results from in vitro studies with mammalian cells. In the study, results of which are presented here, embryos/larvae of zebrafish (Danio rerio) were exposed to 0.02, 0.1 or 0.5 μM TBOEP to investigate expression of genes under control of several nuclear hormone receptors (estrogen receptors (ERs), androgen receptor (AR), thyroid hormone receptor alpha (TRα), mineralocorticoid receptor (MR), glucocorticoid receptor (GR), aryl hydrocarbon (AhR), peroxisome proliferator-activated receptor alpha (PPARα), and pregnane × receptor (P × R)) pathways at 120 hpf. Exposure to 0.5 μM TBOEP significantly (p < 0.05, one-way analysis of variance) up-regulated expression of estrogen receptors (ERs, er1, er2a, and er2b) genes and ER-associated genes (vtg4, vtg5, pgr, ncor, and ncoa3), indicating TBOEP modulates the ER pathway. In contrast, expression of most genes (mr, 11βhsd, ube2i,and adrb2b) associated with the mineralocorticoid receptor (MR) pathway were significantly down-regulated. Furthermore, in vitro mammalian cell-based (MDA-kb2 and H4IIE-luc) receptor transactivation assays, were also conducted to investigate possible agonistic or antagonistic effects on AR- and AhR-mediated pathways. In mammalian cells, none of these pathways were

  8. The interaction of diadenosine polyphosphates with P2x-receptors in the guinea-pig isolated vas deferens.

    Science.gov (United States)

    Westfall, T D; McIntyre, C A; Obeid, S; Bowes, J; Kennedy, C; Sneddon, P

    1997-05-01

    1. The site(s) at which diadenosine 5',5"'-P1,P4-tetraphosphate (AP4A) and diadenosine 5', 5"'-P1,P5-pentaphosphate (AP5A) act to evoke contraction of the guinea-pig isolated vas deferens was studied by use of a series of P2-receptor antagonists and the ecto-ATPase inhibitor 6-N,N-diethyl-D-beta,gamma-dibromomethyleneATP (ARL 67156). 2. Pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) (300 nM - 30 microM), suramin (3-100 microM) and pyridoxal-5'-phosphate (P-5-P) (3-1000 microM) inhibited contractions evoked by equi-effective concentrations of AP5A (3 microM), AP4A (30 microM) and alpha,beta-methyleneATP (alpha,beta-meATP) (1 microM), in a concentration-dependent manner and abolished them at the highest concentrations used. 3. PPADS was more potent than suramin, which in turn was more potent than P-5-P. PPADS inhibited AP5A, AP4A and alpha,beta-meATP with similar IC50 values. No significant difference was found between IC50 values for suramin against alpha,beta-meATP and AP5A or alpha,beta-meATP and AP4A, but suramin was more than 2.5 times more potent against AP4A than AP5A. P-5-P showed the same pattern of antagonism. 4. Desensitization of the P2xi-receptor by alpha,beta-meATP abolished contractions evoked by AP5A (3 microM) and AP4A (30 microM), but had no effect on those elicited by noradrenaline (100 microM). 5. ARL 67156 (100 microM) reversibly potentiated contractions evoked by AP4A (30 microM) by 61%, but caused a small, significant decrease in the mean response to AP5A (3 microM). 6. It is concluded that AP4A and AP5A act at the P2xi-receptor, or a site similar to the P2xi-receptor, to evoke contraction of the guinea-pig isolated vas deferens. Furthermore, the potency of AP4A, but not AP5A, appears to be inhibited by an ecto-enzyme which is sensitive to ARL 67156.

  9. DMPD: Modulation of Toll-interleukin 1 receptor mediated signaling. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 15662540 Modulation of Toll-interleukin 1 receptor mediated signaling. Li X, Qin J.... J Mol Med. 2005 Apr;83(4):258-66. Epub 2005 Jan 21. (.png) (.svg) (.html) (.csml) Show Modulation of Toll-i...nterleukin 1 receptor mediated signaling. PubmedID 15662540 Title Modulation of Toll-interleukin 1 receptor

  10. P2Y2 and P2Y4 receptors regulate pancreatic Ca²+-activated K+ channels differently

    DEFF Research Database (Denmark)

    Klærke, Susanne Edeling Hede; Amstrup, Jan; Klærke, Dan Arne

    2005-01-01

    Extracellular ATP is an important regulator of transepithelial transport in a number of tissues. In pancreatic ducts, we have shown that ATP modulates epithelial K+ channels via purinergic receptors, most likely the P2Y2 and P2Y4 receptors, but the identity of the involved K+ channels was not cle...

  11. 2,3,7,8-tetrachlorodibenzo-p-dioxin decrease expression of aryl hydrocarbon receptor in peripheral lymphocyte of β-thalassemia major patients.

    Science.gov (United States)

    Ghatrehsamani, Mahdi; Soleimani, Masoud; Esfahani, Behjat Al-Sadat Moayedi; Hakemi, Mazdak Ganjalikhani; Shirzad, Hedayatollah; Eskandari, Nahid; Adib, Minoo

    2015-01-01

    β-thalassemia major is a hereditary disease with inefficient erythropoiesis. Level of inflammatory cytokine is elevated in these patients. In this study, we investigate the effect of aryl hydrocarbon receptor (AhR) ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), on the expression of inflammatory mediators in β-thalassemia major patient's lymphocytes. Peripheral blood mononuclear cells of patients and healthy participants was isolated and cultured in favor of lymphocytes increment. Based on the treatment, we divided the cell into four groups. The orders of group's treatments were no treatment, tumor necrosis factor-α (TNF-α) treatment, TNF-α and TCDD treatment, TCDD treatment in Group 1-4, respectively. After cell culture, we extracted the cells RNA and converted them to cDNA. Real-time polymerase chain reaction was performed to assessment relative expression of caspase-1, NLRP3, and AhR. We compared all patient groups with equal healthy (control) groups. Results showed that expression of caspase-1 in patients (Groups 1 and 2) was significantly lower than healthy individuals (P 0.05). Expression of AhR in other groups of patients (3 and 4) was significantly lower than control groups (P < 0.05). Expression of caspase-1 in Group 4 was significantly larger than the control group (P < 0.001). We show here that chronic inflammation decrease caspase-1 expression and exposure of human lymphocytes to TCDD promote caspase-1 expression. Furthermore, activation of AhR with TCDD decreases AhR expression in lymphocytes of β-thalassemia major disease.

  12. Purinergic receptors in the endocrine and exocrine pancreas.

    Science.gov (United States)

    Novak, I

    2008-09-01

    The pancreas is a complex gland performing both endocrine and exocrine functions. In recent years there has been increasing evidence that both endocrine and exocrine cells possess purinergic receptors, which influence processes such as insulin secretion and epithelial ion transport. Most commonly, these processes have been viewed separately. In beta cells, stimulation of P2Y(1) receptors amplifies secretion of insulin in the presence of glucose. Nucleotides released from secretory granules could also contribute to autocrine/paracrine regulation in pancreatic islets. In addition to P2Y(1) receptors, there is also evidence for other P2 and adenosine receptors in beta cells (P2Y(2), P2Y(4), P2Y(6), P2X subtypes and A(1) receptors) and in glucagon-secreting alpha cells (P2X(7), A(2) receptors). In the exocrine pancreas, acini release ATP and ATP-hydrolysing and ATP-generating enzymes. P2 receptors are prominent in pancreatic ducts, and several studies indicate that P2Y(2), P2Y(4), P2Y(11), P2X(4) and P2X(7) receptors could regulate secretion, primarily by affecting Cl(-) and K(+) channels and intracellular Ca(2+) signalling. In order to understand the physiology of the whole organ, it is necessary to consider the full complement of purinergic receptors on different cells as well as the structural and functional relation between various cells within the whole organ. In addition to the possible physiological function of purinergic receptors, this review analyses whether the receptors could be potential therapeutic targets for drug design aimed at treatment of pancreatic diseases.

  13. C-X-C Chemokine Receptor Type 4 Plays a Crucial Role in Mediating Oxidative Stress-Induced Podocyte Injury.

    Science.gov (United States)

    Mo, Hongyan; Wu, Qinyu; Miao, Jinhua; Luo, Congwei; Hong, Xue; Wang, Yongping; Tang, Lan; Hou, Fan Fan; Liu, Youhua; Zhou, Lili

    2017-08-20

    Oxidative stress plays a role in mediating podocyte injury and proteinuria. However, the underlying mechanism remains poorly understood. In this study, we investigated the potential role of C-X-C chemokine receptor type 4 (CXCR4), the receptor for stromal cell-derived factor 1α (SDF-1α), in mediating oxidative stress-induced podocyte injury. In mouse model of adriamycin nephropathy (ADR), CXCR4 expression was significantly induced in podocytes as early as 3 days. This was accompanied by an increased upregulation of oxidative stress in podocyte, as demonstrated by malondialdehyde assay, nitrotyrosine staining and secretion of 8-hydroxy-2'-deoxyguanosine in urine, and induction of NOX2 and NOX4, major subunits of NADPH oxidase. CXCR4 was also induced in human kidney biopsies with proteinuric kidney diseases and colocalized with advanced oxidation protein products (AOPPs), an established oxidative stress trigger. Using cultured podocytes and mouse model, we found that AOPPs induced significant loss of podocyte marker Wilms tumor 1 (WT1), nephrin, and podocalyxin, accompanied by upregulation of desmin both in vitro and in vivo. Furthermore, AOPPs worsened proteinuria and aggravated glomerulosclerosis in ADR. These effects were associated with marked activation of SDF-1α/CXCR4 axis in podocytes. Administration of AMD3100, a specific inhibitor of CXCR4, reduced proteinuria and ameliorated podocyte dysfunction and renal fibrosis triggered by AOPPs in mice. In glomerular miniorgan culture, AOPPs also induced CXCR4 expression and downregulated nephrin and WT1. Innovation and Conclusion: These results suggest that chemokine receptor CXCR4 plays a crucial role in mediating oxidative stress-induced podocyte injury, proteinuria, and renal fibrosis. CXCR4 could be a new target for mitigating podocyte injury, proteinuria, and glomerular sclerosis in proteinuric chronic kidney disease. Antioxid. Redox Signal. 27, 345-362.

  14. Aryl hydrocarbon receptor activation by 2,3,7,8-tetrachlorodibenzo-p-dioxin impairs human B lymphopoiesis

    International Nuclear Information System (INIS)

    Li, Jinpeng; Phadnis-Moghe, Ashwini S.; Crawford, Robert B.; Kaminski, Norbert E.

    2017-01-01

    The homeostasis of peripheral B cell compartment requires lifelong B lymphopoiesis from hematopoietic stem cells (HSC). As a result, the B cell repertoire is susceptible to disruptions of hematopoiesis. Increasing evidence, primarily from rodent models, shows that the aryl hydrocarbon receptor (AHR) regulates hematopoiesis. To study the effects of persistent AHR activation on human B cell development, a potent AHR agonist and known environmental contaminant, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was utilized. An in vitro B cell development model system was established by co-culturing human cord blood-derived HSCs with irradiated human primary bone marrow stromal cells. Using this in vitro model, we found that TCDD significantly suppressed the total number of hematopoietic stem and progenitor cells (HSPC) in a concentration-dependent manner. Cell death analysis demonstrated that the decrease in cell number was not due to cytotoxicity by TCDD. In addition, TCDD markedly decreased CD34 expression on HSPCs. Structure-activity relationship studies using dioxin congeners demonstrated a correlation between the relative AHR binding affinity and the magnitude of decrease in the number of HSPCs and CD34 expression, suggesting that AHR mediates the observed TCDD-elicited changes in HSPCs. Moreover, a significant reduction in lineage committed B cell-derived from HSCs was observed in the presence of TCDD, indicating impairment of human B cell development. Similar effects of TCDD were observed regardless of the use of stromal cells in cultures indicating a direct effect of TCDD on HSCs. Collectively, we demonstrate that AHR activation by TCDD on human HSCs impairs early stages of human B lymphopoiesis.

  15. Pregnane X receptor-dependent induction of the CYP3A4 gene by o,p'-1,1,1,-trichloro-2,2-bis (p-chlorophenyl)ethane.

    Science.gov (United States)

    Medina-Díaz, Irma M; Arteaga-Illán, Georgina; de León, Mario Bermudez; Cisneros, Bulmaro; Sierra-Santoyo, Adolfo; Vega, Libia; Gonzalez, Frank J; Elizondo, Guillermo

    2007-01-01

    CYP3A4, the predominant cytochrome P450 (P450) expressed in human liver and intestine, contributes to the metabolism of approximately half the drugs in clinical use today. CYP3A4 catalyzes the 6beta-hydroxylation of a number of steroid hormones and is involved in the bioactivation of environmental procarcinogens. The expression of CYP3A4 is affected by several stimuli, including environmental factors such as insecticides and pesticides. The o,p'-1,1,1,-trichloro-2,2-bis (p-chlorophenyl)ethane (DDT) isomer of DDT comprises approximately 20% of technical grade DDT, which is an organochloride pesticide. We have recently shown that o,p'-DDT exposure increases CYP3A4 mRNA levels in HepG2 cells. To determine the mechanism by which o,p'-DDT induces CYP3A4 expression, transactivation and electrophoretic mobility shift assays were carried out, revealing that o,p'-DDT activates the CYP3A4 gene promoter through the pregnane X receptor (PXR). CYP3A4 gene promoter activation resulted in both an increase in CYP3A4 mRNA levels and an increase in the total CYP3A4 activity in HepG2 cells. We also observed induction of CYP3A4 and mouse Cyp3a11 mRNA in the intestine of CYP3A4-transgenic mice after exposure to 1 mg/kg o,p'-DDT. At higher doses, a decrease of CYP3A4 inducibility was observed together with an increase in levels of interleukin 6 mRNA, a proinflammatory cytokine that strongly represses CYP3A4 transcription. The present study indicates that regulation of other genes under PXR control may be altered by o,p'-DDT exposure.

  16. Organometallic chemical vapor deposition and characterization of ZnGe(1-x)Si(x)P2-Ge alloys on GaP substrates

    Science.gov (United States)

    Xing, G. C.; Bachmann, Klaus J.; Posthill, J. B.; Timmons, M. L.

    1993-01-01

    The epitaxial growth of ZnGe(1-x)Si(x)P2-Ge alloys on GaP substrates by open tube organometallic chemical vapor deposition (OMCVD) is reported. The chemical composition of the alloys characterized by energy dispersive X-ray spectroscopy shows that alloys with x up to 0.13 can be deposited on (001) GaP. Epitaxial growth with mirror smooth surface morphology was achieved for x less than or equal to 0.05. Transmission electron microscopy (TEM) micrographs of these alloys show specular epitaxy and the absence of microstructural defects indicating a defect density of less than 10(exp 7) cm(sup -2). Selected area electron diffraction pattern of the alloy shows that the epitaxial layer crystallizes in the chalcopyrite structure with relatively weak superlattice reflections indicating certain degree of randomness in the cation sublattice. Hall measurements show that the alloys are p-type, like the unalloyed films; the carrier concentration, however, dropped about 10 times from 2 x 10(exp 18) to 2 x 10(exp 17) cm(sup -3). Absorption measurements indicate that the band tailing in the absorption spectra of the alloy was shifted about 0.04 eV towards shorter wavelength as compared to the unalloyed material. Diodes fabricated from the n(+)-GaP/p-ZnSiP2-ZnGeP2-Ge heterostructure at x = 0.05 have a reverse break-down voltage of -10.8 V and a reverse saturation current density of approximately 6 x 10(exp -8) A/sq cm.

  17. Sphingosine 1-phosphate receptor activation enhances BMP-2-induced osteoblast differentiation

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Chieri [Division of Rheumatology, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501 (Japan); Iwasaki, Tsuyoshi, E-mail: tsuyo-i@huhs.ac.jp [Division of Pharmacotherapy, Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, 1-3-6 Minatojima, Chuo-ku, Kobe 650-8530 (Japan); Kitano, Sachie; Tsunemi, Sachi; Sano, Hajime [Division of Rheumatology, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501 (Japan)

    2012-06-22

    Highlights: Black-Right-Pointing-Pointer We investigated the role of S1P signaling for osteoblast differentiation. Black-Right-Pointing-Pointer Both S1P and FTY enhanced BMP-2-stimulated osteoblast differentiation by C2C12 cells. Black-Right-Pointing-Pointer S1P signaling enhanced BMP-2-stimulated Smad and ERK phosphorylation by C2C12 cells. Black-Right-Pointing-Pointer MEK/ERK signaling is a pathway underlying S1P signaling for osteoblast differentiation. -- Abstract: We previously demonstrated that sphingosine 1-phosphate (S1P) receptor-mediated signaling induced proliferation and prostaglandin productions by synovial cells from rheumatoid arthritis (RA) patients. In the present study we investigated the role of S1P receptor-mediated signaling for osteoblast differentiation. We investigated osteoblast differentiation using C2C12 myoblasts, a cell line derived from murine satellite cells. Osteoblast differentiation was induced by the treatment of bone morphogenic protein (BMP)-2 in the presence or absence of either S1P or FTY720 (FTY), a high-affinity agonist of S1P receptors. Osteoblast differentiation was determined by osteoblast-specific transcription factor, Runx2 mRNA expression, alkaline phosphatase (ALP) activity and osteocalcin production by the cells. Smad1/5/8 and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation was examined by Western blotting. Osteocalcin production by C2C12 cells were determined by ELISA. Runx2 expression and ALP activity by BMP-2-stimulated C2C12 cells were enhanced by addition of either S1P or FTY. Both S1P and FTY enhanced BMP-2-induced ERK1/2 and Smad1/5/8 phosphorylation. The effect of FTY was stronger than that of S1P. S1P receptor-mediated signaling on osteoblast differentiation was inhibited by addition of mitogen-activated protein kinase/ERK kinase (MEK) 1/2 inhibitor, indicating that the S1P receptor-mediated MEK1/2-ERK1/2 signaling pathway enhanced BMP-2-Smad signaling. These results indicate that S1P

  18. Purinergic receptors in the endocrine and exocrine pancreas

    DEFF Research Database (Denmark)

    Novak, I

    2008-01-01

    The pancreas is a complex gland performing both endocrine and exocrine functions. In recent years there has been increasing evidence that both endocrine and exocrine cells possess purinergic receptors, which influence processes such as insulin secretion and epithelial ion transport. Most commonly......, there is also evidence for other P2 and adenosine receptors in beta cells (P2Y(2), P2Y(4), P2Y(6), P2X subtypes and A(1) receptors) and in glucagon-secreting alpha cells (P2X(7), A(2) receptors). In the exocrine pancreas, acini release ATP and ATP-hydrolysing and ATP-generating enzymes. P2 receptors...

  19. p75 Neurotrophin Receptor Cleavage by α- and γ-Secretases Is Required for Neurotrophin-mediated Proliferation of Brain Tumor-initiating Cells*

    Science.gov (United States)

    Forsyth, Peter A.; Krishna, Niveditha; Lawn, Samuel; Valadez, J. Gerardo; Qu, Xiaotao; Fenstermacher, David A.; Fournier, Michelle; Potthast, Lisa; Chinnaiyan, Prakash; Gibney, Geoffrey T.; Zeinieh, Michele; Barker, Philip A.; Carter, Bruce D.; Cooper, Michael K.; Kenchappa, Rajappa S.

    2014-01-01

    Malignant gliomas are highly invasive, proliferative, and resistant to treatment. Previously, we have shown that p75 neurotrophin receptor (p75NTR) is a novel mediator of invasion of human glioma cells. However, the role of p75NTR in glioma proliferation is unknown. Here we used brain tumor-initiating cells (BTICs) and show that BTICs express neurotrophin receptors (p75NTR, TrkA, TrkB, and TrkC) and their ligands (NGF, brain-derived neurotrophic factor, and neurotrophin 3) and secrete NGF. Down-regulation of p75NTR significantly decreased proliferation of BTICs. Conversely, exogenouous NGF stimulated BTIC proliferation through α- and γ-secretase-mediated p75NTR cleavage and release of its intracellular domain (ICD). In contrast, overexpression of the p75NTR ICD induced proliferation. Interestingly, inhibition of Trk signaling blocked NGF-stimulated BTIC proliferation and p75NTR cleavage, indicating a role of Trk in p75NTR signaling. Further, blocking p75NTR cleavage attenuated Akt activation in BTICs, suggesting role of Akt in p75NTR-mediated proliferation. We also found that p75NTR, α-secretases, and the four subunits of the γ-secretase enzyme were elevated in glioblastoma multiformes patients. Importantly, the ICD of p75NTR was commonly found in malignant glioma patient specimens, suggesting that the receptor is activated and cleaved in patient tumors. These results suggest that p75NTR proteolysis is required for BTIC proliferation and is a novel potential clinical target. PMID:24519935

  20. p75 neurotrophin receptor cleavage by α- and γ-secretases is required for neurotrophin-mediated proliferation of brain tumor-initiating cells.

    Science.gov (United States)

    Forsyth, Peter A; Krishna, Niveditha; Lawn, Samuel; Valadez, J Gerardo; Qu, Xiaotao; Fenstermacher, David A; Fournier, Michelle; Potthast, Lisa; Chinnaiyan, Prakash; Gibney, Geoffrey T; Zeinieh, Michele; Barker, Philip A; Carter, Bruce D; Cooper, Michael K; Kenchappa, Rajappa S

    2014-03-21

    Malignant gliomas are highly invasive, proliferative, and resistant to treatment. Previously, we have shown that p75 neurotrophin receptor (p75NTR) is a novel mediator of invasion of human glioma cells. However, the role of p75NTR in glioma proliferation is unknown. Here we used brain tumor-initiating cells (BTICs) and show that BTICs express neurotrophin receptors (p75NTR, TrkA, TrkB, and TrkC) and their ligands (NGF, brain-derived neurotrophic factor, and neurotrophin 3) and secrete NGF. Down-regulation of p75NTR significantly decreased proliferation of BTICs. Conversely, exogenouous NGF stimulated BTIC proliferation through α- and γ-secretase-mediated p75NTR cleavage and release of its intracellular domain (ICD). In contrast, overexpression of the p75NTR ICD induced proliferation. Interestingly, inhibition of Trk signaling blocked NGF-stimulated BTIC proliferation and p75NTR cleavage, indicating a role of Trk in p75NTR signaling. Further, blocking p75NTR cleavage attenuated Akt activation in BTICs, suggesting role of Akt in p75NTR-mediated proliferation. We also found that p75NTR, α-secretases, and the four subunits of the γ-secretase enzyme were elevated in glioblastoma multiformes patients. Importantly, the ICD of p75NTR was commonly found in malignant glioma patient specimens, suggesting that the receptor is activated and cleaved in patient tumors. These results suggest that p75NTR proteolysis is required for BTIC proliferation and is a novel potential clinical target.

  1. Estrogen-Related Receptor Alpha Confers Methotrexate Resistance via Attenuation of Reactive Oxygen Species Production and P53 Mediated Apoptosis in Osteosarcoma Cells

    Directory of Open Access Journals (Sweden)

    Peng Chen

    2014-01-01

    Full Text Available Osteosarcoma (OS is a malignant tumor mainly occurring in children and adolescents. Methotrexate (MTX, a chemotherapy agent, is widely used in treating OS. However, treatment failures are common due to acquired chemoresistance, for which the underlying molecular mechanisms are still unclear. In this study, we report that overexpression of estrogen-related receptor alpha (ERRα, an orphan nuclear receptor, promoted cell survival and blocked MTX-induced cell death in U2OS cells. We showed that MTX induced ROS production in MTX-sensitive U2OS cells while ERRα effectively blocked the ROS production and ROS associated cell apoptosis. Our further studies demonstrated that ERRα suppressed ROS induction of tumor suppressor P53 and its target genes NOXA and XAF1 which are mediators of P53-dependent apoptosis. In conclusion, this study demonstrated that ERRα plays an important role in the development of MTX resistance through blocking MTX-induced ROS production and attenuating the activation of p53 mediated apoptosis signaling pathway, and points to ERRα as a novel target for improving osteosarcoma therapy.

  2. Ku proteins function as corepressors to regulate farnesoid X receptor-mediated gene expression

    International Nuclear Information System (INIS)

    Ohno, Masae; Kunimoto, Masaaki; Nishizuka, Makoto; Osada, Shigehiro; Imagawa, Masayoshi

    2009-01-01

    The farnesoid X receptor (FXR; NR1H4) is a member of the nuclear receptor superfamily and regulates the expression of genes involved in enterohepatic circulation and the metabolism of bile acids. Based on functional analyses, nuclear receptors are divided into regions A-F. To explore the cofactors interacting with FXR, we performed a pull-down assay using GST-fused to the N-terminal A/B region and the C region, which are required for the ligand-independent transactivation and DNA-binding, respectively, of FXR, and nuclear extracts from HeLa cells. We identified DNA-dependent protein kinase catalytic subunit (DNA-PKcs), Ku80, and Ku70 as FXR associated factors. These proteins are known to have an important role in DNA repair, recombination, and transcription. DNA-PKcs mainly interacted with the A/B region of FXR, whereas the Ku proteins interacted with the C region and with the D region (hinge region). Chromatin immunoprecipitation assays revealed that the Ku proteins associated with FXR on the bile salt export pump (BSEP) promoter. Furthermore, we demonstrated that ectopic expression of the Ku proteins decreased the promoter activity and expression of BSEP gene mediated by FXR. These results suggest that the Ku proteins function as corepressors for FXR.

  3. Role of the hinge region of glucocorticoid receptor for HEXIM1-mediated transcriptional repression

    International Nuclear Information System (INIS)

    Yoshikawa, Noritada; Shimizu, Noriaki; Sano, Motoaki; Ohnuma, Kei; Iwata, Satoshi; Hosono, Osamu; Fukuda, Keiichi; Morimoto, Chikao

    2008-01-01

    We previously reported that HEXIM1 (hexamethylene bisacetamide-inducible protein 1), which suppresses transcription elongation via sequestration of positive transcription elongation factor b (P-TEFb) using 7SK RNA as a scaffold, directly associates with glucocorticoid receptor (GR) to suppress glucocorticoid-inducible gene activation. Here, we revealed that the hinge region of GR is essential for its interaction with HEXIM1, and that oxosteroid receptors including GR show sequence homology in their hinge region and interact with HEXIM1, whereas the other members of nuclear receptors do not. We also showed that HEXIM1 suppresses GR-mediated transcription in two ways: sequestration of P-TEFb by HEXIM1 and direct interaction between GR and HEXIM1. In contrast, peroxisome proliferator-activated receptor γ-dependent gene expression is negatively modulated by HEXIM1 solely via sequestration of P-TEFb. We, therefore, conclude that HEXIM1 may act as a gene-selective transcriptional regulator via direct interaction with certain transcriptional regulators including GR and contribute to fine-tuning of, for example, glucocorticoid-mediated biological responses

  4. Study of TiO2(1 1 0)-p(1x1), p(1x2) and p(1x3) surface structures by impact collision ion scattering spectroscopy (ICISS)

    International Nuclear Information System (INIS)

    Asari, E.; Souda, R.

    2000-01-01

    The surface structure of TiO 2 (1 1 0)-p(1x1), p(1x2) and p(1x3) were studied using impact collision ion scattering spectroscopy (ICISS). We found that (i) the height of bridging oxygen for the p(1x1) is comparative to that of bulk structure, (ii) the p(1x2) surface has the added Ti 2 O 3 unit rows proposed by Onishi et al. and also the oxygen atoms rows between Ti 2 O 3 unit rows and (iii) the p(1x3) surface is constructed with the same added Ti 2 O 3 unit rows as that in the p(1x2) surface, but the bridging oxygen rows exist between the Ti 2 O 3 unit rows

  5. Combined genetic and pharmacological inhibition of TRPV1 and P2X3 attenuates colorectal hypersensitivity and afferent sensitization

    OpenAIRE

    Kiyatkin, Michael E.; Feng, Bin; Schwartz, Erica S.; Gebhart, G. F.

    2013-01-01

    The ligand-gated channels transient receptor potential vanilloid 1 (TRPV1) and P2X3 have been reported to facilitate colorectal afferent neuron sensitization, thus contributing to organ hypersensitivity and pain. In the present study, we hypothesized that TRPV1 and P2X3 cooperate to modulate colorectal nociception and afferent sensitivity. To test this hypothesis, we employed TRPV1-P2X3 double knockout (TPDKO) mice and channel-selective pharmacological antagonists and evaluated combined chann...

  6. The roles of P2Y2 purinergic receptors in osteoblasts and mechanotransduction.

    Directory of Open Access Journals (Sweden)

    Yanghui Xing

    Full Text Available We previously demonstrated, using osteoblastic MC3T3-E1 cells, that P2Y2 purinergic receptors are involved in osteoblast mechanotransduction. In this study, our objective was to further investigate, using a knockout mouse model, the roles of P2Y2 receptors in bone mechanobiology. We first examined bone structure with micro-CT and measured bone mechanical properties with three point bending experiments in both wild type mice and P2Y2 knockout mice. We found that bones from P2Y2 knockout mice have significantly decreased bone volume, bone thickness, bone stiffness and bone ultimate breaking force at 17 week old age. In order to elucidate the mechanisms by which P2Y2 receptors contribute to bone biology, we examined differentiation and mineralization of bone marrow cells from wild type and P2Y2 knockout mice. We found that P2Y2 receptor deficiency reduces the differentiation and mineralization of bone marrow cells. Next, we compared the response of primary osteoblasts, from both wild type and P2Y2 knockout mice, to ATP and mechanical stimulation (oscillatory fluid flow, and found that osteoblasts from wild type mice have a stronger response, in terms of ERK1/2 phosphorylation, to both ATP and fluid flow, relative to P2Y2 knockout mice. However, we did not detect any difference in ATP release in response to fluid flow between wild type and P2Y2 knock out osteoblasts. Our findings suggest that P2Y2 receptors play important roles in bone marrow cell differentiation and mineralization as well as in bone cell mechanotransduction, leading to an osteopenic phenotype in P2Y2 knockout mice.

  7. Novel 2-aminotetralin and 3-aminochroman derivatives as selective serotonin 5-HT7 receptor agonists and antagonists.

    Science.gov (United States)

    Holmberg, Pär; Sohn, Daniel; Leideborg, Robert; Caldirola, Patrizia; Zlatoidsky, Pavel; Hanson, Sverker; Mohell, Nina; Rosqvist, Susanne; Nordvall, Gunnar; Johansson, Anette M; Johansson, Rolf

    2004-07-29

    The understanding of the physiological role of the G-protein coupled serotonin 5-HT(7) receptor is largely rudimentary. Therefore, selective and potent pharmacological tools will add to the understanding of serotonergic effects mediated through this receptor. In this report, we describe two compound classes, chromans and tetralins, encompassing compounds with nanomolar affinity for the 5-HT(7) receptor and with good selectivity. Within theses classes, we have discovered both agonists and antagonists that can be used for further understanding of the pharmacology of the 5-HT(7) receptor.

  8. Oxidative stress augments toll-like receptor 8 mediated neutrophilic responses in healthy subjects

    Directory of Open Access Journals (Sweden)

    Matsunaga Kazuto

    2009-06-01

    Full Text Available Abstract Background Excessive oxidative stress has been reported to be generated in inflamed tissues and contribute to the pathogenesis of inflammatory lung diseases, exacerbations of which induced by viral infections are associated with toll-like receptor (TLR activation. Among these receptors, TLR8 has been reported as a key receptor that recognizes single-strand RNA virus. However, it remains unknown whether TLR8 signaling is potentiated by oxidative stress. The aim of this study is to examine whether oxidative stress modulates TLR8 signaling in vitro. Methods Human peripheral blood neutrophils were obtained from healthy non-smokers and stimulated with TLR 7/8 agonist imidazoquinoline resiquimod (R848 in the presence or absence of hydrogen peroxide (H2O2. Neutrophilic responses including cytokine release, superoxide production and chemotaxis were examined, and the signal transduction was also analyzed. Results Activation of TLR8, but not TLR7, augmented IL-8 release. The R848-augmented IL-8 release was significantly potentiated by pretreatment with H2O2 (p L-cysteine reversed this potentiation. The combination of H2O2 and R848 significantly potentiated NF-kB phosphorylation and IkBα degradation. The H2O2-potentiated IL-8 release was suppressed by MG-132, a proteosome inhibitor, and by dexamethasone. The expressions of TLR8, myeloid differentiation primary response gene 88 (MyD88, and tumor necrosis factor receptor-associated factor 6 (TRAF6 were not affected by H2O2. Conclusion TLR8-mediated neutrophilic responses were markedly potentiated by oxidative stress, and the potentiation was mediated by enhanced NF-kB activation. These results suggest that oxidative stress might potentiate the neutrophilic inflammation during viral infection.

  9. An Aryl Hydrocarbon Receptor from the Salamander Ambystoma mexicanum Exhibits Low Sensitivity to 2,3,7,8-Tetrachlorodibenzo-p-dioxin.

    Science.gov (United States)

    Shoots, Jenny; Fraccalvieri, Domenico; Franks, Diana G; Denison, Michael S; Hahn, Mark E; Bonati, Laura; Powell, Wade H

    2015-06-02

    Structural features of the aryl hydrocarbon receptor (AHR) can underlie species- and population-specific differences in its affinity for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). These differences often explain variations in TCDD toxicity. Frogs are relatively insensitive to dioxin, and Xenopus AHRs bind TCDD with low affinity. Weak TCDD binding results from the combination of three residues in the ligand-binding domain: A354 and A370, and N325. Here we sought to determine whether this mechanism of weak TCDD binding is shared by other amphibian AHRs. We isolated an AHR cDNA from the Mexican axolotl (Ambystoma mexicanum). The encoded polypeptide contains identical residues at positions that confer low TCDD affinity to X. laevis AHRs (A364, A380, and N335), and homology modeling predicts they protrude into the binding cavity. Axolotl AHR bound one-tenth the TCDD of mouse AHR in velocity sedimentation analysis, and in transactivation assays, the EC50 for TCDD was 23 nM, similar to X. laevis AHR1β (27 nM) and greater than AHR containing the mouse ligand-binding domain (0.08 nM). Sequence, modeled structure, and function indicate that axolotl AHR binds TCDD weakly, predicting that A. mexicanum lacks sensitivity toTCDD toxicity. We hypothesize that this characteristic of axolotl and Xenopus AHRs arose in a common ancestor of the Caudata and Anura.

  10. Stimulation of accumbal GABAA receptors inhibits delta2-, but not delta1-, opioid receptor-mediated dopamine efflux in the nucleus accumbens of freely moving rats.

    Science.gov (United States)

    Aono, Yuri; Kiguchi, Yuri; Watanabe, Yuriko; Waddington, John L; Saigusa, Tadashi

    2017-11-15

    The nucleus accumbens contains delta-opioid receptors that may reduce inhibitory neurotransmission. Reduction in GABA A receptor-mediated inhibition of accumbal dopamine release due to delta-opioid receptor activation should be suppressed by stimulating accumbal GABA A receptors. As delta-opioid receptors are divided into delta2- and delta1-opioid receptors, we analysed the effects of the GABA A receptor agonist muscimol on delta2- and delta1-opioid receptor-mediated accumbal dopamine efflux in freely moving rats using in vivo microdialysis. Drugs were administered intracerebrally through the dialysis probe. Doses of compounds indicate total amount administered (mol) during 25-50min infusions. The delta2-opioid receptor agonist deltorphin II (25.0nmol)- and delta1-opioid receptor agonist DPDPE (5.0nmol)-induced increases in dopamine efflux were inhibited by the delta2-opioid receptor antagonist naltriben (1.5nmol) and the delta1-opioid receptor antagonist BNTX (150.0pmol), respectively. Muscimol (250.0pmol) inhibited deltorphin II (25.0nmol)-induced dopamine efflux. The GABA A receptor antagonist bicuculline (50.0pmol), which failed to affect deltorphin II (25.0nmol)-induced dopamine efflux, counteracted the inhibitory effect of muscimol on deltorphin II-induced dopamine efflux. Neither muscimol (250.0pmol) nor bicuculline (50.0 and 500.0pmol) altered DPDPE (5.0nmol)-induced dopamine efflux. The present results show that reduction in accumbal GABA A receptor-mediated inhibition of dopaminergic activity is necessary to produce delta2-opioid receptor-induced increase in accumbal dopamine efflux. This study indicates that activation of delta2- but not delta1-opioid receptors on the cell bodies and/or terminals of accumbal GABAergic interneurons inhibits GABA release and, accordingly, decreases GABA A receptor-mediated inhibition of dopaminergic terminals, resulting in enhanced accumbal dopamine efflux. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. A bioluminescence resonance energy transfer 2 (BRET2) assay for monitoring seven transmembrane receptor and insulin receptor crosstalk

    DEFF Research Database (Denmark)

    Sanni, Samra Joke; Kulahin, Nikolaj; Jorgensen, Rasmus

    2017-01-01

    The angiotensin AT1 receptor is a seven transmembrane (7TM) receptor, which mediates the regulation of blood pressure. Activation of angiotensin AT1 receptor may lead to impaired insulin signaling indicating crosstalk between angiotensin AT1 receptor and insulin receptor signaling pathways....... To elucidate the molecular mechanisms behind this crosstalk, we applied the BRET2 technique to monitor the effect of angiotensin II on the interaction between Rluc8 tagged insulin receptor and GFP2 tagged insulin receptor substrates 1, 4, 5 (IRS1, IRS4, IRS5) and Src homology 2 domain-containing protein (Shc......). We demonstrate that angiotensin II reduces the interaction between insulin receptor and IRS1 and IRS4, respectively, while the interaction with Shc is unaffected, and this effect is dependent on Gαq activation. Activation of other Gαq-coupled 7TM receptors led to a similar reduction in insulin...

  12. D1 receptors in the nucleus accumbens-shell, but not the core, are involved in mediating ethanol-seeking behavior of alcohol-preferring (P) rats.

    Science.gov (United States)

    Hauser, S R; Deehan, G A; Dhaher, R; Knight, C P; Wilden, J A; McBride, W J; Rodd, Z A

    2015-06-04

    Clinical and preclinical research suggest that activation of the mesolimbic dopamine (DA) system is involved in mediating the rewarding actions of drugs of abuse, as well as promoting drug-seeking behavior. Inhibition of DA D1 receptors in the nucleus accumbens (Acb) can reduce ethanol (EtOH)-seeking behavior of non-selective rats triggered by environmental context. However, to date, there has been no research on the effects of D1 receptor agents on EtOH- seeking behavior of high alcohol-preferring (P) rats following prolonged abstinence. The objective of the present study was to examine the effects of microinjecting the D1 antagonist SCH 23390 or the D1 agonist A-77636 into the Acb shell or Acb core on spontaneous recovery of EtOH-seeking behavior. After 10 weeks of concurrent access to EtOH and water, P rats underwent seven extinction sessions (EtOH and water withheld), followed by 2 weeks in their home cages without access to EtOH or operant sessions. In the 2nd week of the home cage phase, rats were bilaterally implanted with guide cannula aimed at the Acb shell or Acb core; rats were allowed 7d ays to recover before EtOH-seeking was assessed by the Pavlovian Spontaneous Recovery (PSR) model. Administration of SCH23390 (1μg/side) into the Acb shell inhibited responding on the EtOH lever, whereas administration of A-77636 (0.125μg/side) increased responding on the EtOH lever. Microinfusion of D1 receptor agents into the Acb core did not alter responding on the EtOH lever. Responses on the water lever were not altered by any of the treatments. The results suggest that activation of D1 receptors within the Acb shell, but not Acb core, are involved in mediating PSR of EtOH-seeking behavior of P rats. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  13. Purinergic 2X receptors play a role in evoking the exercise pressor reflex in rats with peripheral artery insufficiency.

    Science.gov (United States)

    Stone, Audrey J; Yamauchi, Katsuya; Kaufman, Marc P

    2014-02-01

    Purinergic 2X (P2X) receptors on the endings of thin fiber afferents have been shown to play a role in evoking the exercise pressor reflex in cats. In this study, we attempted to extend this finding to decerebrated, unanesthetized rats whose femoral arteries were either freely perfused or were ligated 72 h before the start of the experiment. We first established that our dose of pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS; 10 mg/kg), a P2X receptor antagonist, attenuated the pressor response to α,β-methylene ATP (10 μg/kg), a P2X receptor agonist. We then compared the exercise pressor reflex before and after infusing PPADS into the arterial supply of the hindlimb muscles that were statically contracted. In rats with freely perfused femoral arteries, the peak pressor responses to contraction were not significantly attenuated by PPADS (before PPADS: 19 ± 2 mmHg, 13 min after PPADS: 17 ± 2 mmHg, and 25 min after PPADS: 17 ± 3 mmHg). Likewise, the cardioaccelerator and renal sympathetic nerve responses were not significantly attenuated. In contrast, we found that in rats whose femoral arteries were ligated PPADS significantly attenuated the peak pressor responses to contraction (before PPADS: 37 ± 5 mmHg, 13 min after PPADS: 27 ± 6 mmHg, and 25 min after PPADS: 25 ± 5 mmHg; P reflex in rats whose femoral arteries were ligated but play only a minimal role in evoking the reflex in rats whose femoral arteries were freely perfused.

  14. Toll-like receptor 7-mediated enhancement of contextual fear memory in mice.

    Science.gov (United States)

    Kubo, Yasunori; Yanagawa, Yoshiki; Matsumoto, Machiko; Hiraide, Sachiko; Kobayashi, Masanobu; Togashi, Hiroko

    2012-10-01

    Toll-like receptor (TLR) 7 recognizes viral single-stranded RNA and triggers production of the type I interferons (IFNs) IFN-α and IFN-β. Imiquimod, a synthetic TLR7 ligand, induces production of type I IFNs and is used clinically as an antiviral and antitumor drug. In the present study, we examined the effect of imiquimod on conditioned and innate fear behaviors in mice. Imiquimod was administered 2, 4, or 15 h before contextual fear conditioning. Imiquimod treatment 4 or 15 h before fear conditioning significantly enhanced context-dependent freezing behavior. This imiquimod-induced enhancement of fear-related behaviors was observed 120 h after fear conditioning. In contrast, imiquimod failed to enhance context-dependent freezing behavior in TLR7 knockout mice. Imiquimod had no significant effect on pain threshold or on innate fear-related behavior, as measured by the elevated plus-maze. The levels of type I IFN mRNA in the brain were significantly increased at 2 h after imiquimod treatment. Imiquimod also increased interleukin (IL)-1β mRNA expression in the brain at 4 h following administration, while mRNA expression of F4/80, a macrophage marker, was unaffected by imiquimod treatment. Our findings suggest that TLR7-mediated signaling enhances contextual fear memory in mice, possibly by inducing the expression of type I IFNs and IL-1β in the brain. Copyright © 2012 Elsevier Inc. All rights reserved.

  15. Estrogen-mediated inactivation of FOXO3a by the G protein-coupled estrogen receptor GPER

    International Nuclear Information System (INIS)

    Zekas, Erin; Prossnitz, Eric R.

    2015-01-01

    Estrogen (17β-estradiol) promotes the survival and proliferation of breast cancer cells and its receptors represent important therapeutic targets. The cellular actions of estrogen are mediated by the nuclear estrogen receptors ERα and ERβ as well as the 7-transmembrane spanning G protein-coupled estrogen receptor (GPER). We previously reported that estrogen activates the phosphoinositide 3-kinase (PI3Kinase) pathway via GPER, resulting in phosphatidylinositol (3,4,5)-trisphosphate (PIP3) production within the nucleus of breast cancer cells; however, the mechanisms and consequences of this activity remained unclear. MCF7 breast cancer cells were transfected with GFP-fused Forkhead box O3 (FOXO3) as a reporter to assess localization in response to estrogen stimulation. Inhibitors of PI3Kinases and EGFR were employed to determine the mechanisms of estrogen-mediated FOXO3a inactivation. Receptor knockdown with siRNA and the selective GPER agonist G-1 elucidated the estrogen receptor(s) responsible for estrogen-mediated FOXO3a inactivation. The effects of selective estrogen receptor modulators and downregulators (SERMs and SERDs) on FOXO3a in MCF7 cells were also determined. Cell survival (inhibition of apoptosis) was assessed by caspase activation. In the estrogen-responsive breast cancer cell line MCF7, FOXO3a inactivation occurs on a rapid time scale as a result of GPER, but not ERα, stimulation by estrogen, established by the GPER-selective agonist G-1 and knockdown of GPER and ERα. GPER-mediated inactivation of FOXO3a is effected by the p110α catalytic subunit of PI3Kinase as a result of transactivation of the EGFR. The SERMs tamoxifen and raloxifene, as well as the SERD ICI182,780, were active in mediating FOXO3a inactivation in a GPER-dependent manner. Additionally, estrogen-and G-1-mediated stimulation of MCF7 cells results in a decrease in caspase activation under proapoptotic conditions. Our results suggest that non-genomic signaling by GPER contributes

  16. Regulation of brain capillary endothelial cells by P2Y receptors coupled to Ca2+, phospholipase C and mitogen-activated protein kinase.

    Science.gov (United States)

    Albert, J L; Boyle, J P; Roberts, J A; Challiss, R A; Gubby, S E; Boarder, M R

    1997-11-01

    1. The blood-brain barrier is formed by capillary endothelial cells and is regulated by cell-surface receptors, such as the G protein-coupled P2Y receptors for nucleotides. Here we investigated some of the characteristics of control of brain endothelial cells by these receptors, characterizing the phospholipase C and Ca2+ response and investigating the possible involvement of mitogen-activated protein kinases (MAPK). 2. Using an unpassaged primary culture of rat brain capillary endothelial cells we showed that ATP, UTP and 2-methylthio ATP (2MeSATP) give similar and substantial increases in cytosolic Ca2+, with a rapid rise to peak followed by a slower decline towards basal or to a sustained plateau. Removal of extracellular Ca2+ had little effect on the peak Ca2+-response, but resulted in a more rapid decline to basal. There was no response to alpha,beta-MethylATP (alpha,beta MeATP) in these unpassaged cells, but a response to this P2X agonist was seen after a single passage. 3. ATP (log EC50 -5.1+/-0.2) also caused an increase in the total [3H]-inositol (poly)phosphates ([3H]-InsPx) in the presence of lithium with a rank order of agonist potency of ATP=UTP=UDP>ADP, with 2MeSATP and alpha,beta MeATP giving no detectable response. 4. Stimulating the cells with ATP or UTP gave a rapid rise in the level of inositol 1,4,5-trisphosphate (Ins(1,4,5)P3), with a peak at 10 s followed by a decline to a sustained plateau phase. 2MeSATP gave no detectable increase in the level of Ins(1,4,5)P3. 5. None of the nucleotides tested affected basal cyclic AMP, while ATP and ATPgammaS, but not 2MeSATP, stimulated cyclic AMP levels in the presence of 5 microM forskolin. 6. Both UTP and ATP stimulated tyrosine phosphorylation of p42 and p44 mitogen-activated protein kinase (MAPK), while 2MeSATP gave a smaller increase in this index of MAPK activation. By use of a peptide kinase assay, UTP gave a substantial increase in MAPK activity with a concentration-dependency consistent with

  17. Pyrid-2-yl and 2-CyanoPhenyl fused heterocyclic compounds as human P2X3 inhibitors: a combined approach based on homology modelling, docking and QSAR analysis.

    Science.gov (United States)

    Janardhan, Sridhara; Seth, Subhendu; Viswanadhan, Vellarkad N

    2014-02-01

    P2X receptors are hetero-oligomeric proteins that function as membrane ion channels and are gated by extracellular ATP. The hP2X[Formula: see text] subunit is a constituent of the channels on a subset of sensory neurons involved in pain signaling, where ATP released by damaged and inflamed tissue can initiate action potentials. Hence, the inhibition of ATP-activated P2X3 receptor is an exciting approach for the treatment of inflammatory and neuropathic pain. Recently, the crystal structures of zebrafish P2X4 (zP2X4) were obtained in closed, apo state (PDB ID: 3I5D) and ATP-bound, open state (PDB ID: 4DW1). These structures were used to develop a homology model of human P2X3 (hP2X3 in order to identify through docking studies, the binding modes of known P2X3 inhibitors and their key active site interactions, along with a pharmacophore-based 3D-QSAR model for a series of 136 Pyrid-2-yl and 2-CyanoPhenyl fused heterocyclic compounds. These 3D-QSAR models have been developed with different combinations of training and test set divisions obtained by random separation, Jarvis-Patrick clustering, K-means clustering and sphere exclusion methods. The best predictive 3D-QSAR model resulted in training set R2 of 0.75, internal test set Q2 of 0.74, Pearson-R value of 0.87 and root mean square error of 0.37. The information generated by the pharmacophore model and docking analyses using the homology model provides valuable clues to design novel potent hP2X3 inhibitors.

  18. p38 mediates mechanical allodynia in a mouse model of type 2 diabetes

    Directory of Open Access Journals (Sweden)

    Hong Yu

    2010-05-01

    Full Text Available Abstract Background Painful Diabetic Neuropathy (PDN affects more than 25% of patients with type 2 diabetes; however, the pathogenesis remains unclear due to lack of knowledge of the molecular mechanisms leading to PDN. In our current study, we use an animal model of type 2 diabetes in order to understand the roles of p38 in PDN. Previously, we have demonstrated that the C57BLK db/db (db/db mouse, a model of type 2 diabetes that carries the loss-of-function leptin receptor mutant, develops mechanical allodynia in the hind paws during the early stage (6-12 wk of age of diabetes. Using this timeline of PDN, we can investigate the signaling mechanisms underlying mechanical allodynia in the db/db mouse. Results We studied the role of p38 in lumbar dorsal root ganglia (LDRG during the development of mechanical allodynia in db/db mice. p38 phosphorylation was detected by immunoblots at the early stage of mechanical allodynia in LDRG of diabetic mice. Phosphorylated p38 (pp38 immunoreactivity was detected mostly in the small- to medium-sized LDRG neurons during the time period of mechanical allodynia. Treatment with an antibody against nerve growth factor (NGF significantly inhibited p38 phosphorylation in LDRG of diabetic mice. In addition, we detected higher levels of inflammatory mediators, including cyclooxygenase (COX 2, inducible nitric oxide synthases (iNOS, and tumor necrosis factor (TNF-α in LDRG neurons of db/db mice compared to non-diabetic db+ mice. Intrathecal delivery of SB203580, a p38 inhibitor, significantly inhibited the development of mechanical allodynia and the upregulation of COX2, iNOS and TNF-α. Conclusions Our findings suggest that NGF activated-p38 phosphorylation mediates mechanical allodynia in the db/db mouse by upregulation of multiple inflammatory mediators in LDRG.

  19. Genetic deletion of the P2Y2 receptor offers significant resistance to development of lithium-induced polyuria accompanied by alterations in PGE2 signaling.

    Science.gov (United States)

    Zhang, Yue; Pop, Ioana L; Carlson, Noel G; Kishore, Bellamkonda K

    2012-01-01

    Lithium (Li)-induced polyuria is due to resistance of the medullary collecting duct (mCD) to the action of arginine vasopressin (AVP), apparently mediated by increased production of PGE(2). We previously reported that the P2Y(2) receptor (P2Y(2)-R) antagonizes the action of AVP on the mCD and may play a role in Li-induced polyuria by enhancing the production of PGE(2) in mCD. Hence, we hypothesized that genetic deletion of P2Y(2)-R should ameliorate Li-induced polyuria. Wild-type (WT) or P2Y(2)-R knockout (KO) mice were fed normal or Li-added diets for 14 days and euthanized. Li-induced polyuria, and decreases in urine osmolality and AQP2 protein abundance in the renal medulla, were significantly less compared with WT mice despite the lack of differences in Li intake or terminal serum or inner medullary tissue Li levels. Li-induced increased urinary excretion of PGE(2) was not affected in KO mice. However, prostanoid EP(3) receptor (EP3-R) protein abundance in the renal medulla of KO mice was markedly lower vs. WT mice, irrespective of the dietary regimen. The protein abundances of other EP-Rs were not altered across the groups irrespective of the dietary regimen. Ex vivo stimulation of mCD with PGE(2) generated significantly more cAMP in Li-fed KO mice (130%) vs. Li-fed WT mice (100%). Taken together, these data suggest 1) genetic deletion of P2Y(2)-R offers significant resistance to the development of Li-induced polyuria; and 2) this resistance is apparently due to altered PGE(2) signaling mediated by a marked decrease in EP3-R protein abundance in the medulla, thus attenuating the EP3-mediated decrease in cAMP levels in mCD.

  20. The α7-nicotinic acetylcholine receptor mediates the sensitivity of gastric cancer cells to taxanes.

    Science.gov (United States)

    Tu, Chao-Chiang; Huang, Chien-Yu; Cheng, Wan-Li; Hung, Chin-Sheng; Uyanga, Batzorig; Wei, Po-Li; Chang, Yu-Jia

    2016-04-01

    Gastric cancer is difficult to cure because most patients are diagnosed at an advanced disease stage. Systemic chemotherapy remains an important therapy for gastric cancer, but both progression-free survival and disease-free survival associated with various combination regimens are limited because of refractoriness and chemoresistance. Accumulating evidence has revealed that the homomeric α7-nicotinic acetylcholine receptor (A7-nAChR) promotes human gastric cancer by driving cancer cell proliferation, migration, and metastasis. Therefore, A7-nAChR may serve as a potential therapeutic target for gastric cancer. However, the role of A7-nAChR in taxane therapy for gastric cancer was unclear. Cells were subjected to A7-nAChR knockdown (A7-nAChR KD) using short interfering RNA (siRNA). The anti-proliferative effects of taxane were assessed via 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT), terminal deoxynucleotidyl transferase-mediated nick-end labeling (TUNEL), and cell cycle distribution assays. A7-nAChR-KD cells exhibited low resistance to docetaxel and paclitaxel treatment, as measured by the MTT assay. Following paclitaxel treatment, the proportion of apoptotic cells was higher among A7-nAChR-KD cells than among scrambled control cells, as measured by cell cycle distribution and TUNEL assays. Further molecular analyses showed a reduction in the pAKT levels and a dramatic increase in the Bad levels in paclitaxel-treated A7-nAChR-KD cells but not in scrambled control cells. Following paclitaxel treatment, the level of Bax was slightly increased in both cell populations, whereas Poly (ADP-ribose) polymerase (PARP) cleavage was increased only in A7-nAChR-KD cells. These findings indicate that A7-nAChR-KD cells are more sensitive to paclitaxel treatment. We conclude that A7-nAChR may be a key biomarker for assessing the chemosensitivity of gastric cancer cells to taxane.

  1. Decrement of GABAA receptor-mediated inhibitory postsynaptic currents in dentate granule cells in epileptic hippocampus.

    Science.gov (United States)

    Isokawa, M

    1996-05-01

    1. Inhibitory postsynaptic currents (IPSCs) were studied in hippocampal dentate granule cells (DGCs) in the pilocarpine model and human temporal lobe epilepsy, with the use of the whole cell patch-clamp recording technique in slice preparations. 2. In the pilocarpine model, hippocampal slices were prepared from rats that were allowed to experience spontaneous seizures for 2 mo. Human hippocampal specimens were obtained from epileptic patients who underwent surgical treatment for medically intractable seizures. 3. IPSCs were generated by single perforant path stimulation and recorded at a membrane potential (Vm) of 0 mV near the reversal potential of glutamate excitatory postsynaptic currents in the voltage-clamp recording. IPSCs were pharmacologically identified as gamma-aminobutyric acid-A (GABAA) IPSCs by 10 microM bicuculline methiodide. 4. During low-frequency stimulation, IPSCs were not different in amplitude among non-seizure-experienced rat hippocampi, human nonsclerotic hippocampi, seizure-experienced rat hippocampi, and human sclerotic hippocampi. In the last two groups of DGCs, current-clamp recordings indicated the presence of prolonged excitatory postsynaptic potentials (EPSPs) mediated by the N-methyl-D-aspartate (NMDA) receptor. 5. High-frequency stimulation, administered at Vm = -30 mV to activate NMDA currents, reduced GABAA IPSC amplitude specifically in seizure-experienced rat hippocampi (t = 2.5, P < 0.03) and human sclerotic hippocampi (t = 7.7, P < 0.01). This reduction was blocked by an NMDA receptor antagonist, 2-amino-5-phosphonovaleric acid (APV) (50 microM). The time for GABAA IPSCs to recover to their original amplitude was also shortened by the application of APV. 6. I conclude that, when intensively activated, NMDA receptor-mediated excitatory transmission may interact with GABAergic synaptic inhibition in DGCs in seizure-experienced hippocampus to transiently reduce GABA(A) receptor-channel function. Such interactions may contribute to

  2. Platelet alpha-2 adrenergic receptor-mediated phosphoinositide responses in endogenous depression

    International Nuclear Information System (INIS)

    Mori, Hideki; Koyama, Tsukasa; Yamashita, Itaru

    1991-01-01

    We have previously indicated that epinephrine stimulates phosphoinositide (PI) hydrolysis by activating alpha-2 adrenergic receptors in human platelets. This method involves the measurement of the accumulation of [ 3 H]-inositol-1-phosphate (IP-1) as an index of Pl hydrolysis; lithium is added to inhibit the metabolism of IP-1, thus giving an enhanced signal. In the present study, we assessed the platelet alpha-2 adrenergic receptor-mediated PI responses in samples from 15 unmedicated patients with endogenous depression and 15 age- and sex-matched control subjects. The responses to epinephrine in the depressed patients were significantly higher than those of the controls, whereas the basal values did not differ significantly. These results support the hypothesis that platelet alpha-2 adrenergic receptors may be supersensitive in patients with endogenous depression

  3. Monkey liver cytochrome P450 2C19 is involved in R- and S-warfarin 7-hydroxylation.

    Science.gov (United States)

    Hosoi, Yoshio; Uno, Yasuhiro; Murayama, Norie; Fujino, Hideki; Shukuya, Mitsunori; Iwasaki, Kazuhide; Shimizu, Makiko; Utoh, Masahiro; Yamazaki, Hiroshi

    2012-12-15

    Cynomolgus monkeys are widely used as primate models in preclinical studies. However, some differences are occasionally seen between monkeys and humans in the activities of cytochrome P450 enzymes. R- and S-warfarin are model substrates for stereoselective oxidation in humans. In this current research, the activities of monkey liver microsomes and 14 recombinantly expressed monkey cytochrome P450 enzymes were analyzed with respect to R- and S-warfarin 6- and 7-hydroxylation. Monkey liver microsomes efficiently mediated both R- and S-warfarin 7-hydroxylation, in contrast to human liver microsomes, which preferentially catalyzed S-warfarin 7-hydroxylation. R-Warfarin 7-hydroxylation activities in monkey liver microsomes were not inhibited by α-naphthoflavone or ketoconazole, and were roughly correlated with P450 2C19 levels and flurbiprofen 4-hydroxylation activities in microsomes from 20 monkey livers. In contrast, S-warfarin 7-hydroxylation activities were not correlated with the four marker drug oxidation activities used. Among the 14 recombinantly expressed monkey P450 enzymes tested, P450 2C19 had the highest activities for R- and S-warfarin 7-hydroxylations. Monkey P450 3A4 and 3A5 slowly mediated R- and S-warfarin 6-hydroxylations. Kinetic analysis revealed that monkey P450 2C19 had high V(max) and low K(m) values for R-warfarin 7-hydroxylation, comparable to those for monkey liver microsomes. Monkey P450 2C19 also mediated S-warfarin 7-hydroxylation with V(max) and V(max)/K(m) values comparable to those for recombinant human P450 2C9. R-warfarin could dock favorably into monkey P450 2C19 modeled. These results collectively suggest high activities for monkey liver P450 2C19 toward R- and S-warfarin 6- and 7-hydroxylation in contrast to the saturation kinetics of human P450 2C9-mediated S-warfarin 7-hydroxylation. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. Synergistic effect of pacritinib with erlotinib on JAK2-mediated resistance in epidermal gowth factor receptor mutation-positive non-small cell lung Cancer.

    Science.gov (United States)

    Ochi, Nobuaki; Isozaki, Hideko; Takeyama, Masami; Singer, Jack W; Yamane, Hiromichi; Honda, Yoshihiro; Kiura, Katsuyuki; Takigawa, Nagio

    2016-06-10

    The combination effect of pacritinib, a novel JAK2/FLT3 inhibitor, with erlotinib, the epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), on non-small cell lung cancer cells with EGFR activating mutations was investigated. The combination showed synergistic effects on JAK2-mediated EGFR TKI-resistant PC-9/ER3 cells in some cases. The combination markedly suppressed pAKT and pERK although pSTAT3 expression was similar regardless of treatment with the pacritinib, pacritinib + erlotinib, or control in PC-9/ER3 cells. Receptor tyrosine kinase array profiling demonstrated that pacritinib suppressed MET in the PC-9/ER3 cells. The combined treatment of pacritinib and erlotinib in PC-9/ER3 xenografts showed more tumor shrinkage compared with each drug as monotherapy. Western blotting revealed that pMET in tumor samples was inhibited. These results suggest MET suppression by pacritinib may play a role in overcoming the EGFR-TKI resistance mediated by JAK2 in the PC-9/ER3 cells. In conclusion, pacritinib combined with EGFR-TKI might be a potent strategy against JAK2-mediated EGFR-TKI resistance. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Identification of Functionally Important Residues of the Rat P2X4 Receptor by Alanine Scanning Mutagenesis of the Dorsal Fin and Left Flipper Domains

    Czech Academy of Sciences Publication Activity Database

    Tvrdoňová, Vendula; Rokic, Milos Boro; Stojilkovic, S. S.; Zemková, Hana

    2014-01-01

    Roč. 9, č. 11 (2014), e112902 E-ISSN 1932-6203 R&D Projects: GA ČR(CZ) GBP304/12/G069; GA MŠk(CZ) ED1.1.00/02.0109; GA MŠk(CZ) EE2.3.30.0025 Grant - others:Univerzita Karlova(CZ) 3446/11 Institutional support: RVO:67985823 Keywords : purinergic receptor * P2X * ATP * binding pocket * gating * signal transmission * partial agonists Subject RIV: ED - Physiology Impact factor: 3.234, year: 2014

  6. Caffeine Inhibits the Activation of Hepatic Stellate Cells Induced by Acetaldehyde via Adenosine A2A Receptor Mediated by the cAMP/PKA/SRC/ERK1/2/P38 MAPK Signal Pathway

    Science.gov (United States)

    Yang, Wanzhi; Wang, Qi; Zhao, Han; Yang, Feng; Lv, Xiongwen; Li, Jun

    2014-01-01

    Hepatic stellate cell (HSC) activation is an essential event during alcoholic liver fibrosis. Evidence suggests that adenosine aggravates liver fibrosis via the adenosine A2A receptor (A2AR). Caffeine, which is being widely consumed during daily life, inhibits the action of adenosine. In this study, we attempted to validate the hypothesis that caffeine influences acetaldehyde-induced HSC activation by acting on A2AR. Acetaldehyde at 50, 100, 200, and 400 μM significantly increased HSC-T6 cells proliferation, and cell proliferation reached a maximum at 48 h after exposure to 200 μM acetaldehyde. Caffeine and the A2AR antagonist ZM241385 decreased the cell viability and inhibited the expression of procollagen type I and type III in acetaldehyde-induced HSC-T6 cells. In addition, the inhibitory effect of caffeine on the expression of procollagen type I was regulated by A2AR-mediated signal pathway involving cAMP, PKA, SRC, and ERK1/2. Interestingly, caffeine’s inhibitory effect on the expression of procollagen type III may depend upon the A2AR-mediated P38 MAPK-dependent pathway. Conclusions: Caffeine significantly inhibited acetaldehyde-induced HSC-T6 cells activation by distinct A2AR mediated signal pathway via inhibition of cAMP-PKA-SRC-ERK1/2 for procollagen type I and via P38 MAPK for procollagen type III. PMID:24682220

  7. Menthol binding and inhibition of α7-nicotinic acetylcholine receptors.

    Directory of Open Access Journals (Sweden)

    Abrar Ashoor

    Full Text Available Menthol is a common compound in pharmaceutical and commercial products and a popular additive to cigarettes. The molecular targets of menthol remain poorly defined. In this study we show an effect of menthol on the α7 subunit of the nicotinic acetylcholine (nACh receptor function. Using a two-electrode voltage-clamp technique, menthol was found to reversibly inhibit α7-nACh receptors heterologously expressed in Xenopus oocytes. Inhibition by menthol was not dependent on the membrane potential and did not involve endogenous Ca(2+-dependent Cl(- channels, since menthol inhibition remained unchanged by intracellular injection of the Ca(2+ chelator BAPTA and perfusion with Ca(2+-free bathing solution containing Ba(2+. Furthermore, increasing ACh concentrations did not reverse menthol inhibition and the specific binding of [(125I] α-bungarotoxin was not attenuated by menthol. Studies of α7- nACh receptors endogenously expressed in neural cells demonstrate that menthol attenuates α7 mediated Ca(2+ transients in the cell body and neurite. In conclusion, our results suggest that menthol inhibits α7-nACh receptors in a noncompetitive manner.

  8. Identification of aryl hydrocarbon receptor binding targets in mouse hepatic tissue treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin

    International Nuclear Information System (INIS)

    Lo, Raymond; Celius, Trine; Forgacs, Agnes L.; Dere, Edward; MacPherson, Laura; Harper, Patricia; Zacharewski, Timothy; Matthews, Jason

    2011-01-01

    Genome-wide, promoter-focused ChIP-chip analysis of hepatic aryl hydrocarbon receptor (AHR) binding sites was conducted in 8-week old female C57BL/6 treated with 30 μg/kg/body weight 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for 2 h and 24 h. These studies identified 1642 and 508 AHR-bound regions at 2 h and 24 h, respectively. A total of 430 AHR-bound regions were common between the two time points, corresponding to 403 unique genes. Comparison with previous AHR ChIP-chip studies in mouse hepatoma cells revealed that only 62 of the putative target genes overlapped with the 2 h AHR-bound regions in vivo. Transcription factor binding site analysis revealed an over-representation of aryl hydrocarbon response elements (AHREs) in AHR-bound regions with 53% (2 h) and 68% (24 h) of them containing at least one AHRE. In addition to AHREs, E2f-Myc activator motifs previously implicated in AHR function, as well as a number of other motifs, including Sp1, nuclear receptor subfamily 2 factor, and early growth response factor motifs were also identified. Expression microarray studies identified 133 unique genes differentially regulated after 4 h treatment with TCDD. Of which, 39 were identified as AHR-bound genes at 2 h. Ingenuity Pathway Analysis on the 39 AHR-bound TCDD responsive genes identified potential perturbation in biological processes such as lipid metabolism, drug metabolism, and endocrine system development as a result of TCDD-mediated AHR activation. Our findings identify direct AHR target genes in vivo, highlight in vitro and in vivo differences in AHR signaling and show that AHR recruitment does not necessarily result in changes in target gene expression. -- Highlights: ► ChIP-chip analysis of hepatic AHR binding after 2 h and 24 h of TCDD. ► We identified 1642 and 508 AHR-bound regions at 2 h and 24 h. ► 430 regions were common to both time points and highly enriched with AHREs. ► Only 62 putative target regions overlapped AHR-bound regions in

  9. Identification of aryl hydrocarbon receptor binding targets in mouse hepatic tissue treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin

    Energy Technology Data Exchange (ETDEWEB)

    Lo, Raymond; Celius, Trine [Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario (Canada); Forgacs, Agnes L. [Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI (United States); Center for Integrative Toxicology, Michigan State University, East Lansing, MI (United States); Dere, Edward [Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI (United States); MacPherson, Laura [Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario (Canada); Harper, Patricia [Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario (Canada); Research Institute, The Hospital for Sick Children, Toronto, Ontario (Canada); Zacharewski, Timothy [Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI (United States); Center for Integrative Toxicology, Michigan State University, East Lansing, MI (United States); Matthews, Jason, E-mail: jason.matthews@utoronto.ca [Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario (Canada)

    2011-11-15

    Genome-wide, promoter-focused ChIP-chip analysis of hepatic aryl hydrocarbon receptor (AHR) binding sites was conducted in 8-week old female C57BL/6 treated with 30 {mu}g/kg/body weight 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for 2 h and 24 h. These studies identified 1642 and 508 AHR-bound regions at 2 h and 24 h, respectively. A total of 430 AHR-bound regions were common between the two time points, corresponding to 403 unique genes. Comparison with previous AHR ChIP-chip studies in mouse hepatoma cells revealed that only 62 of the putative target genes overlapped with the 2 h AHR-bound regions in vivo. Transcription factor binding site analysis revealed an over-representation of aryl hydrocarbon response elements (AHREs) in AHR-bound regions with 53% (2 h) and 68% (24 h) of them containing at least one AHRE. In addition to AHREs, E2f-Myc activator motifs previously implicated in AHR function, as well as a number of other motifs, including Sp1, nuclear receptor subfamily 2 factor, and early growth response factor motifs were also identified. Expression microarray studies identified 133 unique genes differentially regulated after 4 h treatment with TCDD. Of which, 39 were identified as AHR-bound genes at 2 h. Ingenuity Pathway Analysis on the 39 AHR-bound TCDD responsive genes identified potential perturbation in biological processes such as lipid metabolism, drug metabolism, and endocrine system development as a result of TCDD-mediated AHR activation. Our findings identify direct AHR target genes in vivo, highlight in vitro and in vivo differences in AHR signaling and show that AHR recruitment does not necessarily result in changes in target gene expression. -- Highlights: Black-Right-Pointing-Pointer ChIP-chip analysis of hepatic AHR binding after 2 h and 24 h of TCDD. Black-Right-Pointing-Pointer We identified 1642 and 508 AHR-bound regions at 2 h and 24 h. Black-Right-Pointing-Pointer 430 regions were common to both time points and highly enriched with

  10. Identification of endogenous surrogate ligands for human P2Y12 receptors by in silico and in vitro methods

    International Nuclear Information System (INIS)

    Nonaka, Yosuke; Hiramoto, Takeshi; Fujita, Norihisa

    2005-01-01

    Endogenous ligands acting on a human P2Y 12 receptor, one of the G-protein coupled receptors, were searched by in silico screening against our own database, which contains more than 500 animal metabolites. The in silico screening using the docking software AutoDock resulted in selection of cysteinylleukotrienes (CysLTs) and 5-phosphoribosyl 1-pyrophosphate (PRPP), with high free energy changes, in addition to the known P2Y 12 ligands such as 2MeSADP and ADP. These candidates were subjected to an in vitro Ca 2+ assay using the CHO cells stably expressing P2Y 12 -G 16 α fusion proteins. We found that CysLTE4 and PRPP acted on the P2Y 12 receptor as agonists with the EC 50 values of 1.3 and 7.8 nM, respectively. Furthermore, we analyzed the phylogenetic relationship of the P2Y, P2Y-like, and CysLT receptors based on sequence alignment followed by evolutionary analyses. The analyses showed that the P2Y 12 , P2Y 13 , P2Y 14 , GPR87, CysLT-1, and CysLT-2 receptors formed a P2Y-related receptor subfamily with common sequence motifs in the transmembrane regions

  11. Acetylation of pregnane X receptor protein determines selective function independent of ligand activation

    International Nuclear Information System (INIS)

    Biswas, Arunima; Pasquel, Danielle; Tyagi, Rakesh Kumar; Mani, Sridhar

    2011-01-01

    Research highlights: → Pregnane X receptor (PXR), a major regulatory protein, is modified by acetylation. → PXR undergoes dynamic deacetylation upon ligand-mediated activation. → SIRT1 partially mediates PXR deacetylation. → PXR deacetylation per se induces lipogenesis mimicking ligand-mediated activation. -- Abstract: Pregnane X receptor (PXR), like other members of its class of nuclear receptors, undergoes post-translational modification [PTM] (e.g., phosphorylation). However, it is unknown if acetylation (a major and common form of protein PTM) is observed on PXR and, if it is, whether it is of functional consequence. PXR has recently emerged as an important regulatory protein with multiple ligand-dependent functions. In the present work we show that PXR is indeed acetylated in vivo. SIRT1 (Sirtuin 1), a NAD-dependent class III histone deacetylase and a member of the sirtuin family of proteins, partially mediates deacetylation of PXR. Most importantly, the acetylation status of PXR regulates its selective function independent of ligand activation.

  12. P2Y12 receptor-mediated activation of spinal microglia and p38MAPK pathway contribute to cancer-induced bone pain

    Directory of Open Access Journals (Sweden)

    Liu MJ

    2017-02-01

    Full Text Available Mingjuan Liu,1 Ming Yao,1,2 Hanqi Wang,1 Longsheng Xu,1 Ying Zheng,1 Bing Huang,1 Huadong Ni,1 Shijie Xu,1 Xuyan Zhou,1 Qingquan Lian2 1Department of Anesthesiology and Pain Medicine, The First Hospital of Jiaxing, The First Affiliated Hospital of Jiaxing University, Jiaxing, 2Department of Anesthesiology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, People’s Republic of China Background: Cancer-induced bone pain (CIBP is one of the most challenging clinical problems due to a lack of understanding the mechanisms. Recent evidence has demonstrated that activation of microglial G-protein-coupled P2Y12 receptor (P2Y12R and proinflammatory cytokine production play an important role in neuropathic pain generation and maintenance. However, whether P2Y12R is involved in CIBP remains unknown.Methods: The purpose of this study was to investigate the role of P2Y12R in CIBP and its molecular mechanisms. Using the bone cancer model inoculated with Walker 256 tumor cells into the left tibia of Sprague Dawley rat, we blocked spinal P2Y12R through intrathecal administration of its selective antagonist MRS2395 (400 pmol/µL, 15 µL.Results: We found that not only the ionized calcium-binding adapter molecule 1 (Iba-1-positive microglia in the ipsilateral spinal cord but also mechanical allodynia was significantly inhibited. Furthermore, it decreased the phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK and the production of proinflammatory cytokines interleukin-1β (IL-1β and interleukin-6 (IL-6, whereas it increased tumor necrosis factor-α (TNF-α.Conclusion: Taken together, our present results suggest that microglial P2Y12R in the spinal cord may contribute to CIBP by the activation of spinal microglia and p38MAPK pathway, thus identifying a potential therapeutic target for the treatment of CIBP. Keywords: P2Y12 receptor, cancer-induced bone pain, p38MAPK pathway, cytokines

  13. Pathophysiological consequences of receptor mistraffic: Tales from the platelet P2Y12 receptor.

    Science.gov (United States)

    Cunningham, Margaret R; Aungraheeta, Riyaad; Mundell, Stuart J

    2017-07-05

    Genetic variations in G protein-coupled receptor (GPCR) genes can disrupt receptor function in a wide variety of human genetic diseases, including platelet bleeding disorders. Platelets are critical for haemostasis with inappropriate platelet activation leading to the development of arterial thrombosis, which can result in heart attack and stroke whilst decreased platelet activity is associated with an increased risk of bleeding. GPCRs expressed on the surface of platelets play key roles in regulating platelet activity and therefore function. Receptors include purinergic receptors (P2Y 1 and P2Y 12 ), proteinase-activated receptor (PAR1 and PAR4) and thromboxane recep