Purinoceptor‐operated cationic channels in human B lymphocytes.

Markwardt, Fritz; Löhn, Matthias; Böhm, Thomas; Klapperstück, Manuela

doi:10.1113/jphysiol.1997.sp021847

Cited by 66 publications

(60 citation statements)

References 25 publications

(23 reference statements)

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“…Cloned P2X 7 R's form large pores in HEK cells (Surprenant et al, 1996;Virginio et al, 1999a), but none at all in Xenopus oocytes (Klapperstuck et al, 2000). Human B cells also possess pores of limited permeability that take up YO-PRO-1, but not PI (Markwardt et al, 1997;Gu et al, 2000;Lohn et al, 2001). The data for resting human astrocytes are consistent with this functional profile of the P2X 7 R, and suggest that IL-1β induces a change in the cellular localization of the P2X 7 R, as well as an increase of receptor activity.…”

Section: Discussionmentioning

confidence: 99%

The cytokine IL‐1β transiently enhances P2X₇ receptor expression and function in human astrocytes

Narcisse

Scemes

Zhao

et al. 2004

Glia

176

147

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Extracellular nucleotide di-and triphosphates such as ATP and ADP mediate their effects through purinergic P2 receptors belonging to either the metabotropic P2Y or the ionotropic P2X receptor family. The P2X 7 R is a unique member of the P2X family, which forms a pore in response to ligand stimulation, regulating cell permeability, cytokine release, and/or apoptosis. This receptor is also unique in that its affinity for the ligand benzoyl-benzoyl ATP (BzATP) is at least 10-fold greater than that of ATP. Primary human fetal astrocytes in culture express low-levels of P2X 7 R mRNA and protein, and BzATP induces only a slight influx in intracellular calcium [Ca 2+ ] i , with little demonstrable effect on gene expression or pore formation in these cells. We now show that, following treatment with the proinflammatory cytokine IL-1β, BzATP induces a robust rise in [Ca 2+ ] i with agonist and antagonist profiles indicative of the P2X 7 R. IL-1β also induced the formation of membrane pores as evidenced by the uptake of YO-PRO-1 (375 Da). Quantitative real-time PCR demonstrated transient upregulation of P2X 7 R mRNA in IL-1β-treated cells, while FACS analysis indicated a similar upregulation of P2X 7 R protein at the cell membrane. In multiple sclerosis lesions, immunoreactivity for the P2X 7 R was demonstrated on reactive astrocytes in autopsy brain tissues. In turn, P2X 7 R stimulation increased the production of IL-1-induced nitric oxide synthase activity by astrocytes in culture. These studies suggest that signaling via the P2X 7 R may modulate the astrocytic response to inflammation in the human central nervous system.

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Section: Discussionmentioning

confidence: 99%

The cytokine IL‐1β transiently enhances P2X₇ receptor expression and function in human astrocytes

Narcisse

Scemes

Zhao

et al. 2004

Glia

176

147

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“…For example, activation of cloned P2X 7 receptors expressed in HEK cells results in formation of a pore permeable to cations of up to 900 Da (4 -6) although expression in oocytes apparently does not (26). Similarly, P2X 7 receptors in monocytes and mast cells couple to a dye-permeable pore formation (6, 7) but P2X 7 receptors in B-lymphocytes may or may not depending on the experimental conditions or activation state of the B cells (8,18,27,28). Cultured microglial cells or microglial cell lines also form these large pores upon P2X 7 activation (29, 30), but it is not known whether this occurs in situ in brain slices.…”

Section: Discussionmentioning

confidence: 99%

Differential Assembly of Rat Purinergic P2X7 Receptor in Immune Cells of the Brain and Periphery

Kim

Spelta

Sim

et al. 2001

Journal of Biological Chemistry

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ATP-gated P2X 7 purinoceptors are found in most immune cells of the periphery and the brain where their activation leads to multiple downstream events such as cell permeabilization, apoptosis, and/or cytokine release. P2X 7 receptors do not form heteromeric receptors with any of the other six P2X subunits, and it is not known what type of homomeric assemblies the P2X 7 subunit makes. We constructed and purified an ectodomain protein of the rat P2X 7 receptor (amino acids 60 -323) and used this to generate a monoclonal antibody (Ab) with which to probe P2X 7 receptors in central and peripheral immune cells. In HEK cells expressing rat P2X 7 receptors, the Ab increased the maximum current evoked by BzATP by 3-8-fold with a 5-fold leftward shift in EC 50 concentration. This Ab recognized only a nondenatured, multimeric form of the receptor on blue native-PAGE but did not recognize the denatured form on SDS-PAGE. A C-terminal polyclonal P2X 7 Ab recognized both monomeric subunits on SDS-PAGE and a multimeric complex on blue native-PAGE in this heterologous expression system. With Western blotting using these two Abs, native P2X 7 receptors in peritoneal macrophage and bone marrow cells are shown to exist as a strongly bound multimeric complex, whereas P2X 7 receptors in brain glia and/or astrocytes appear to form only as monomeric subunits.Like most neurotransmitters, extracellular ATP activates both metabotropic (G protein-coupled) receptors, the P2Y receptor family, and ionotropic (ligand-gated) receptors, the P2X receptor family (1). When compared with other ionotropic receptors (e.g. nicotinic), which are primarily or solely expressed in nerve and muscle, P2X receptors are unusual in their wide spread expression in both excitable and non-excitable cells (1-3). There are seven P2X receptors, six of which (P2X 1-6 ) are found in brain and peripheral neurons; additionally, mRNA for P2X 1 , P2X 4 , and the non-neuronal P2X 7 receptor are prominent in many immune cells, particularly monocytes, macrophage, bone marrow, and brain microglia (1-3).The P2X 7 receptor shows 40 -45% amino acid identity with any one of the other P2X receptors; it shares the overall membrane topology of two transmembrane domains, intracellular N and C termini, and the large ectodomain with conservation of the 10 extracellular cysteine residues, although its C-terminal is some 200 amino acids longer than other P2X receptors (1-3). However, the functional sequelae of P2X 7 receptor activation differ strikingly from other P2X receptors. Activation of P2X 7 receptors expressed in mammalian cells, such as HEK 1 or CHO cells, opens both a small cationic channel and a large (up to 900 Da) dye-permeable pore, followed within seconds by extensive membrane blebbing (4, 5); similar events occur upon activation of native P2X 7 receptors in some but not all immune cells expressing this receptor (6 -8). The mechanism(s) underlying formation of the permeabilizing pore and other downstream events such as membrane blebbing are not known but the intracellular ...

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“…Tonsillar B cells as well as human B lymphocytes immortalized by Epstein-Barr virus have been studied by patch-clamp recordings (41,298,299). In both cases, BzATP (EC 50 ϳ15 M) or ATP (EC 50 ϳ100 M) elicited opening of a 9-pS channel that was permeable to small cations, including calcium, but not to choline.…”

Section: Lymphocytesmentioning

confidence: 99%

Molecular Physiology of P2X Receptors

North

2002

Physiological Reviews

2,673

128

3,397

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P2X receptors are membrane ion channels that open in response to the binding of extracellular ATP. Seven genes in vertebrates encode P2X receptor subunits, which are 40–50% identical in amino acid sequence. Each subunit has two transmembrane domains, separated by an extracellular domain (∼280 amino acids). Channels form as multimers of several subunits. Homomeric P2X1, P2X2, P2X3, P2X4, P2X5, and P2X7 channels and heteromeric P2X2/3 and P2X1/5 channels have been most fully characterized following heterologous expression. Some agonists (e.g., αβ-methylene ATP) and antagonists [e.g., 2′,3′- O-(2,4,6-trinitrophenyl)-ATP] are strongly selective for receptors containing P2X1 and P2X3subunits. All P2X receptors are permeable to small monovalent cations; some have significant calcium or anion permeability. In many cells, activation of homomeric P2X7 receptors induces a permeability increase to larger organic cations including some fluorescent dyes and also signals to the cytoskeleton; these changes probably involve additional interacting proteins. P2X receptors are abundantly distributed, and functional responses are seen in neurons, glia, epithelia, endothelia, bone, muscle, and hemopoietic tissues. The molecular composition of native receptors is becoming understood, and some cells express more than one type of P2X receptor. On smooth muscles, P2X receptors respond to ATP released from sympathetic motor nerves (e.g., in ejaculation). On sensory nerves, they are involved in the initiation of afferent signals in several viscera (e.g., bladder, intestine) and play a key role in sensing tissue-damaging and inflammatory stimuli. Paracrine roles for ATP signaling through P2X receptors are likely in neurohypophysis, ducted glands, airway epithelia, kidney, bone, and hemopoietic tissues. In the last case, P2X7 receptor activation stimulates cytokine release by engaging intracellular signaling pathways.

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Purinoceptor‐operated cationic channels in human B lymphocytes.

Cited by 66 publications

References 25 publications

The cytokine IL‐1β transiently enhances P2X₇ receptor expression and function in human astrocytes

The cytokine IL‐1β transiently enhances P2X₇ receptor expression and function in human astrocytes

Differential Assembly of Rat Purinergic P2X7 Receptor in Immune Cells of the Brain and Periphery

Molecular Physiology of P2X Receptors

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Purinoceptor‐operated cationic channels in human B lymphocytes.

Cited by 66 publications

References 25 publications

The cytokine IL‐1β transiently enhances P2X7 receptor expression and function in human astrocytes

The cytokine IL‐1β transiently enhances P2X7 receptor expression and function in human astrocytes

Differential Assembly of Rat Purinergic P2X7 Receptor in Immune Cells of the Brain and Periphery

Molecular Physiology of P2X Receptors

Contact Info

Product

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The cytokine IL‐1β transiently enhances P2X₇ receptor expression and function in human astrocytes

The cytokine IL‐1β transiently enhances P2X₇ receptor expression and function in human astrocytes