Regulation of activity of P2X7 receptor by its splice variants in cultured mouse astrocytes

Kido, Yuuka; Kawahara, Chiyo; Terai, Yasuko; Ohishi, Akihiro; Kobayashi, Satoshi; Hayakawa, Miki; Kamatsuka, Yosuke; Nishida, Kazuhiro

doi:10.1002/glia.22615

Cited by 21 publications

(15 citation statements)

References 31 publications

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“…13) In contrast to the case of astrocytes, neurons in acute slices were not constitutively activated under non-stimulated resting conditions, and this was the same with their primary cultures. 5,13) Although detail mechanism underlying this is unclear, this difference is considered to be due to the difference in cell types, implying different roles of P2X7Rs in astrocytes and neurons. SJL mice are known to exhibit extreme aggression, 29) differing from ddY ones.…”

Section: Discussionmentioning

confidence: 81%

“…The finding that P2X7Rs in in vivo tissue astrocytes, but not neurons, exhibit constitutive activation, is identical to that in in vitro cell culture systems of astrocytes and neurons. 5,12,13) Therefore, it is suggested that under in vivo non-stimulated resting conditions, astrocytic P2X7Rs play roles in the maintenance of brain homeostasis.…”

Section: Discussionmentioning

confidence: 99%

“…13) To determine whether or not this difference is also observed in acute slice preparations, we compared the PI uptake by the two types of astrocytes. As shown in Fig.…”

Section: Functionalities Of P2x7rs In Astrocytes and Neuronsmentioning

confidence: 99%

“…Previously, we demonstrated that in primary cultured mouse astrocytes, P2X7Rs were activated without any exogenous ligands, and that this constitutive activation was due, at least in part, to autocrine/paracrine stimulation by ATP released from astrocytes themselves into restricted intercellular space, 12) regulated by P2X7R splice variants, 13) and involved in regulation of astrocytic engulfing activity. 14) These findings suggest that under non-stimulated resting conditions, P2X7Rs expressed by astrocytes play roles in the maintenance of brain neuronal homeostasis.…”

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confidence: 98%

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Astrocytes, but Not Neurons, Exhibit Constitutive Activation of P2X7 Receptors in Mouse Acute Cortical Slices under Non-stimulated Resting Conditions

Kamatsuka

Fukagawa

Furuta

et al. 2014

Biological & Pharmaceutical Bulletin

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We previously demonstrated that the P2X7 receptor (P2X7R), a purinergic receptor, expressed by mouse cultured cortical astrocytes is constitutively activated without any exogenous stimulus, differing from the case of neurons. It is well known that astrocytic morphology differs between in vitro and in vivo situations, implying different functionalities. Brain acute slices are widely accepted as an in vitro experimental system that reflects in vivo cell conditions better than in vitro cell culture ones. We examined whether astrocytic P2X7Rs exhibited constitutive activation in mouse cortical slices. In acute cortical slices, P2X7R-immunoreactivity was detected in both glial fibrillary acidic protein-immunopositive astrocytes and microtubuleassociated protein 2-immunopositive neurons. Astrocytic, but not neuronal, spontaneous uptake of propidium iodide, an indicator of P2X7R channel/pore activity, was inhibited by representative antagonists of P2X7R, but they had no effect on the uptake by astrocytes in membrane-permeabilized fixed slices. These findings indicate that astrocytes, but not neurons, in acute cortical slices exhibit constitutive activation of P2X7Rs under non-stimulated resting conditions as in the case of cell culture systems.Key words P2X7 receptor; astrocyte; mouse cortical slice; neuron Among purine receptors, in particular, P2X7 receptors (P2X7Rs) have unique characteristics, and are activated by high concentrations (ca. mM) of ATP, resulting in the formation of a non-selective cationic channel/pore, through which large molecules of up to 900 Da can pass. Through activation of P2X7Rs in neurons, cell death is induced via calcium influx, followed by related cellular events, while activation of P2X7Rs expressed by microglia, brain-resident immune cells, causes generation and/or release of reactive oxygen species (ROS) and pro-inflammatory cytokines. These responses help keep the brain environment clean, while under severe pathological conditions, neuronal injury is exacerbated.

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Section: Discussionmentioning

confidence: 81%

Section: Discussionmentioning

confidence: 99%

“…13) To determine whether or not this difference is also observed in acute slice preparations, we compared the PI uptake by the two types of astrocytes. As shown in Fig.…”

Section: Functionalities Of P2x7rs In Astrocytes and Neuronsmentioning

confidence: 99%

mentioning

confidence: 98%

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Astrocytes, but Not Neurons, Exhibit Constitutive Activation of P2X7 Receptors in Mouse Acute Cortical Slices under Non-stimulated Resting Conditions

Kamatsuka

Fukagawa

Furuta

et al. 2014

Biological & Pharmaceutical Bulletin

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“…Two hypothetical mechanisms, namely the gating model and the Pannexin-1 model, have been proposed [3] . In the gating model, pore dilation resulted from longterm ATP action, which leads to additional conformational change [118][119][120][121][122][123][124] . While in the Pannexin-1 model, the conformational changes of the P2X receptor resulted in allosterism of an auxiliary protein coupled with the P2X receptor, such as Pannexin-1, permitting molecules to enter cells through those proteins [125,126] .…”

Section: Questions To Be Answeredmentioning

confidence: 99%

Insights into the channel gating of P2X receptors from structures, dynamics and small molecules

Wang

2016

Acta Pharmacol Sin

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P2X receptors, as ATP-gated non-selective trimeric ion channels, are permeable to Na + , K + and Ca 2+ . Comparing with other ligand-gated ion channel families, P2X receptors are distinct in their unique gating properties and pathophysiological roles, and have attracted attention as promising drug targets for a variety of diseases, such as neuropathic pain, multiple sclerosis, rheumatoid arthritis and thrombus. Several small molecule inhibitors for distinct P2X subtypes have entered into clinical trials. However, many questions regarding the gating mechanism of P2X remain unsolved. The structural determinations of P2X receptors at the resting and ATPbound open states revealed that P2X receptor gating is a cooperative allosteric process involving multiple domains, which marks the beginning of the post-structure era of P2X research at atomic level. Here, we review the current knowledge on the structure-function relationship of P2X receptors, depict the whole picture of allosteric changes during the channel gating, and summarize the active sites that may contribute to new strategies for developing novel allosteric drugs targeting P2X receptors.

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Mechanisms underlying sensitization of P2X7 receptors in astrocytes for induction of ischemic tolerance

Hirayama

Anzai

Koizumi

2021

Glia

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We previously showed that noninvasive mild ischemia (preconditioning; PC) induced ischemic tolerance by upregulation of P2X7 receptors in astrocytes via a hypoxia inducible factor‐1α (HIF‐1α)‐dependent mechanism. The P2X7 receptor is known as a low‐sensitivity P2 receptor that requires a high extracellular ATP (eATP) concentration for activation. PC increased the eATP level but was not sufficient to activate P2X7 receptors. Here, we show that astrocytes possess an elaborate mechanism for activation of P2X7 receptors, thus contributing to ischemic tolerance. Nicotinamide adenine dinucleotide (NAD+) was shown to increase the sensitivity of P2X7 receptors to eATP via ecto‐ADP‐ribosyltransferase 2 (ARTC2)‐catalyzed ADP‐ribosylation in peripheral immune cells. Although ARTC2‐positive signals were mostly absent in the naïve brain, they were selectively increased in astrocytes by PC. The spatiotemporal pattern of PC‐evoked ARTC2 was well associated with that of P2X7 receptors. In the in vitro experiments, NAD+ increased the sensitivity of P2X7 receptors to ATP, and at higher concentrations, NAD+ itself activated P2X7 receptors without eATP in cultured astrocytes. In the in vivo experiments using middle cerebral artery occlusion model mice, the PC‐evoked increase in HIF‐1α in astrocytes was abolished by the ARTC2 inhibitor S + 16a. S + 16a also abolished PC‐evoked ischemic tolerance. Taken together, the results suggested that P2X7 receptors can be sensitized to ATP by NAD+/ARTC2‐catalyzed ADP‐ribosylation, which allows astrocytes to drive P2X7 receptor‐mediated ischemic tolerance even though PC only slightly increases the amount of eATP.

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Regulation of activity of P2X7 receptor by its splice variants in cultured mouse astrocytes

Cited by 21 publications

References 31 publications

Astrocytes, but Not Neurons, Exhibit Constitutive Activation of P2X7 Receptors in Mouse Acute Cortical Slices under Non-stimulated Resting Conditions

Astrocytes, but Not Neurons, Exhibit Constitutive Activation of P2X7 Receptors in Mouse Acute Cortical Slices under Non-stimulated Resting Conditions

Insights into the channel gating of P2X receptors from structures, dynamics and small molecules

Mechanisms underlying sensitization of P2X7 receptors in astrocytes for induction of ischemic tolerance

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