Differential Modulation by Copper and Zinc of P2X<sub>2</sub>and P2X<sub>4</sub> Receptor Function

Xiong, Keming; Peoples, Robert W.; Montgomery, Jennifer; Chiang, Yisheng; Stewart, Randall R.; Weight, Forrest F.; Li, Chaoying

doi:10.1152/jn.1999.81.5.2088

Cited by 87 publications

(89 citation statements)

References 45 publications

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“…Zn 2+ potentiated P2X 2 and P2X 4 channels at 1 -100 mM (27). Cu 2+ at 1 -130 m M also enhanced cloned P2X2 channels, but not P2X4 channels (28). In human P2X 4 channels expressed in Xenopus oocytes, low concentrations (1 -10 m M) of Zn 2+ enhanced the current, while it was inhibited by a high concentration (1 mM) (29).…”

Section: Discussionmentioning

confidence: 89%

Inhibitory Effects of Metals on ATP-Induced Current Through P2X7 Receptor in NG108-15 Cells

Watano

Matsuoka

Kimura

2002

Japanese Journal of Pharmacology

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ABSTRACT-We investigated the effects of heavy metal ions on the ATP-induced nonselective cation current through P2X7 receptor (INS·P2X7) in NG108-15 cells using the whole-cell patch-clamp technique. Cu 2+ inhibited the INS·P2X7 most potently among the metal ions investigated. Other metals such as Ni 2+ , Cd 2+ , Zn 2+ and Co 2+ also inhibited the INS·P2X7 in concentration-dependent manners. The order of potency was Cu 2+ >> Ni 2+ > Cd 2+ > Zn 2+ > Co 2+ with IC50 values of 16 nM, 0.79 mM, 1.2 m M, 3.0 mM and 4.6 mM, respectively. Fe 3+ (10 and 100 mM) and Mn 2+ (10 mM) did not affect the I NS · P2X7 . A high concentration of Mn 2+ (100 m M) slightly inhibited the I NS · P2X7 . When the concentration-response curve of ATP was obtained in the presence of 3 and 10 nM Cu 2+ , the maximal response but not the EC 50 value appeared to be reduced, suggesting that the inhibition is not competitive. These results suggest that under physiological and toxicological conditions, metal ions, such as Cu 2+ , Ni 2+ , Cd 2+ , Zn 2+ and Co 2+ , may modulate P2X 7 receptor channels as inhibitors. Keywords: ATP, P2X7 receptor, Nonselective cation current, Metal ion, NG108-15 cellThe P2X7 receptor is one of seven subtypes (P2X1 -7) of P2X receptors, which are ligand-gated nonselective cation channels (1, 2). It has unique properties compared to the other P2X receptors (3, 4). The P2X7 receptor requires concentrations of ATP (>0.3 mM) much higher than the other P2X (P2X 1 -6 ) receptors for activation (5). The effective form of ATP for the P2X7 receptor is the free base (ATP 4-) (6), and benzoylbenzoic ATP (BzATP) is a more potent agonist than ATP (7 -9).NG108-15 cells are hybrids of mouse neuroblastoma N18TG-2 and rat glioma C6Bu-1 cells and possess the mouse P2X 7 receptor originating from N18TG-2 cells (10). The cDNA sequence of P2X 7 receptor in NG108-15 cells was almost identical (ref. 10; I. Matsuoka, unpubished result of the full length sequence) to that of mouse P2X7 receptor first cloned by Chessell et al. (11) in NTW8 mouse microglial cells. A high concentration (>0.3 mM), but not a low concentration, of ATP activates a nonselective cation current, indicating that the only functional P2X receptor is the P2X7 receptor in NG108-15 cells (7,12,13). Rat and human P2X7 receptors transform themselves from channels to large pores by prolonged application of ATP (8,14), but this does not occur in mouse P2X7 receptors in NG108-15 cells (15). Therefore, the P2X7 receptors in NG108-15 cells are different from those in rat and human macrophages and glial cells.Metals such as vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn) and molybdenum (Mo) are essential trace elements utilized as cofactors of various enzymes (16). Metal ions are known to affect various ion channels (17) MATERIALS AND METHODS Cell cultureNG108-15 cells were grown in high-glucose Dulbecco's modified Eagle's medium supplemented with 7% fetal bovine serum, 100 mM hypoxanthine, 0.4 mM aminopterin and 16 mM thymidine...

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Section: Discussionmentioning

confidence: 89%

Inhibitory Effects of Metals on ATP-Induced Current Through P2X7 Receptor in NG108-15 Cells

Watano

Matsuoka

Kimura

2002

Japanese Journal of Pharmacology

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“…Copper and zinc also modulate other members of the P2X family of receptors, but their effects depend on the receptor subtype. For example, both zinc and copper facilitate the ATP-evoked responses on the P2X 2 receptor (14,15) whereas in the P2X 7 receptor, copper inhibits the ATP-gated currents, whereas zinc is virtually without effect (13). These findings further support the notion that the P2X purinoceptors may have separate metal-binding sites to modulate the channel activity.…”

mentioning

confidence: 72%

“…modulation but not for its potentiating effect (23). The P2X 2 receptor, another member of the P2X receptor family, is potentiated by zinc (14,15); two histidines have been proposed to coordinate zinc in its extracellular domain (29). Because copper also positively modulates the P2X 2 receptor, it is not unlikely that the P2X 2 receptor possesses only a non-selective facilitator trace metal-binding site or a very low affinity inhibitory metal binding-site.…”

Section: Discussionmentioning

confidence: 99%

Histidine 140 Plays a Key Role in the Inhibitory Modulation of the P2X4 Nucleotide Receptor by Copper but Not Zinc

Coddou

Morales

González

et al. 2003

Journal of Biological Chemistry

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To elucidate the role of extracellular histidines in the modulation of the rat P2X 4 receptor by trace metals, we generated single, double, and triple histidine mutants for residues 140, 241, and 286, replacing them with alanines. cDNAs for the wild-type and receptor mutants were expressed in Xenopus laevis oocytes and in human embryonic kidney 293 cells and examined by the two electrode and patch clamp techniques, respectively. Whereas copper inhibited concentration-dependently the ATP-gated currents in the wild-type and in the single or double H241A and H286A receptor mutants, all receptors containing H140A were insensitive to copper in both cell systems. The characteristic bell-shaped concentration-response curve of zinc observed in the wildtype receptor became sigmoid in both oocytes and human embryonic kidney cells expressing the H140A mutant; in these mutants, the zinc potentiation was 2.5-4-fold larger than in the wild-type. Results with the H140T and H140R mutants further support the importance of a histidine residue at this position. We conclude that His-140 is critical for the action of copper, indicating that this histidine residue, but not His-241 or His-286, forms part of the inhibitory allosteric metal-binding site of the P2X 4 receptor, which is distinct from the putative zinc facilitator binding site.The notion that trace metals such as zinc or copper are atypical brain messengers has attracted much attention in view of their emerging role in the modulation of brain excitability (1). The importance of trace metals in synaptic activity is highlighted by the description that both copper and zinc are stored in synaptic vesicles from where they are released by electrical depolarization, reaching a high micromolar concentration at the synaptic cleft (2-4). Trace metals are known to modulate a wide variety of brain ionotropic receptors such as glycine, N-methyl-D-aspartate, ␥-aminobutyric acid, nicotinic, and the novel nucleotide receptors (P2X) family (5-9). The P2X purinoceptors are homomeric or heteromeric membrane channels gated by extracellular ATP and related synthetic nucleotides; North (10) recently reviewed the principles of the molecular physiology of this family of receptors. Within the P2X receptor family, the P2X 4 is the most widely distributed in the central nervous system, including the cerebellum and the CA1 region of the hippocampus, where it has been proposed to play a role in glutamatergic synapses (11).The P2X 4 receptor is an interesting model of an ionic channel differentially modulated by trace metals. Acuñ a-Castillo et al. (12) and Coddou et al. (13) reported that zinc potentiates the ATP-evoked currents whereas copper has an inhibitory effect on the activity of this receptor. Based on these findings, Acuñ aCastillo et al. (12) proposed that trace metals modulate the activity of the P2X 4 receptor via two separate metal-binding sites. One of these sites has a preferential selectivity for copper and is characterized by a non-competitive inhibition of the ATP-gated channel acti...

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“…12). Cu 2ϩ , an allosteric modulator of P2X 2 Rs (Xiong et al, 1999), also evoked a significant increase in frequency at all three concentrations. Frequency increased 1.63 Ϯ 0.12-fold [from 13.8 Ϯ 0.8 to a maximum of 22.5 Ϯ 2.1 cycles/min at 25 M Cu 2ϩ (CuCl 2 )] and recovered to control levels after washout (n ϭ 7) (Fig.…”

Section: Involvement Of Endogenously Released Atpmentioning

confidence: 83%

“…Another possibility is that endogenous purinergic modulation of rhythmic activity may not be limited to a direct, P2Y 1 R-mediated preBötC effect, but an indirect action via P2XRs outside the preBötC. Some support for this is that Cu 2ϩ , which potentiates P2X 2 R currents (Xiong et al, 1999), reversibly increased baseline frequency. Additionally, bath-applied suramin did not alter the frequency effects of ATP in the preBötC, but significantly reduced baseline rhythm.…”

Section: Physiological Role For P2r Signaling In Respiratory Controlmentioning

confidence: 99%

P2Y₁Receptor Modulation of the Pre-Bötzinger Complex Inspiratory Rhythm Generating NetworkIn Vitro

Lorier¹,

Huxtable²,

Robinson³

et al. 2007

J. Neurosci.

154

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ATP is released during hypoxia from the ventrolateral medulla (VLM) and activates purinergic P2 receptors (P2Rs) at unknown loci to offset the secondary hypoxic depression of breathing. In this study, we used rhythmically active medullary slices from neonatal rat to map, in relation to anatomical and molecular markers of the pre-Bötzinger complex (preBötC) (a proposed site of rhythm generation), the effects of ATP on respiratory rhythm and identify the P2R subtypes responsible for these actions. Unilateral microinjections of ATP in a three-dimensional grid within the VLM revealed a "hotspot" where ATP (

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Differential Modulation by Copper and Zinc of P2X₂and P2X₄ Receptor Function

Cited by 87 publications

References 45 publications

Inhibitory Effects of Metals on ATP-Induced Current Through P2X7 Receptor in NG108-15 Cells

Inhibitory Effects of Metals on ATP-Induced Current Through P2X7 Receptor in NG108-15 Cells

Histidine 140 Plays a Key Role in the Inhibitory Modulation of the P2X4 Nucleotide Receptor by Copper but Not Zinc

P2Y₁Receptor Modulation of the Pre-Bötzinger Complex Inspiratory Rhythm Generating NetworkIn Vitro

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Differential Modulation by Copper and Zinc of P2X2and P2X4 Receptor Function

Cited by 87 publications

References 45 publications

Inhibitory Effects of Metals on ATP-Induced Current Through P2X7 Receptor in NG108-15 Cells

Inhibitory Effects of Metals on ATP-Induced Current Through P2X7 Receptor in NG108-15 Cells

Histidine 140 Plays a Key Role in the Inhibitory Modulation of the P2X4 Nucleotide Receptor by Copper but Not Zinc

P2Y1Receptor Modulation of the Pre-Bötzinger Complex Inspiratory Rhythm Generating NetworkIn Vitro

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Differential Modulation by Copper and Zinc of P2X₂and P2X₄ Receptor Function

P2Y₁Receptor Modulation of the Pre-Bötzinger Complex Inspiratory Rhythm Generating NetworkIn Vitro