| P2RX7 Protein | |
|---|---|
| Protein Name | P2X Purinoceptor 7 (P2X7) |
| Gene | [P2RX7](/entities/p2rx7-gene) |
| UniProt ID | [Q99572](https://www.uniprot.org/uniprot/Q99572) |
| PDB IDs | 5U1L, 5U1U, 5U1V, 5U1W, 5U1X, 6U9V |
| Molecular Weight | ~68.6 kDa (monomer) |
| Subcellular Localization | Plasma membrane, lipid rafts |
| Protein Family | P2X purinergic receptor family |
| Oligomeric State | Homotrimer |
| Chromosomal Location | 12q24.31 |
The P2X7 receptor (P2X purinoceptor 7) is an ATP-gated cation channel that occupies a unique position among purinergic receptors due to its dual function as both a rapid ion channel and a macropore-forming complex[1]. Unlike other P2X family members, P2X7 requires millimolar concentrations of extracellular ATP for activation — concentrations typically reached only during cellular stress, injury, or death — making it a danger signal sensor in the central nervous system[2]. P2X7 is predominantly expressed on microglia, astrocytes, and oligodendrocytes, with lower expression on neurons, positioning it as a master regulator of neuroinflammation[3].
In the context of neurodegeneration, P2X7 activation triggers the NLRP3 inflammasome assembly, leading to caspase-1-dependent maturation and release of pro-inflammatory cytokines IL-1β and IL-18, as well as pyroptotic cell death via gasdermin D pore formation[4]. This pathway is critically implicated in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, and Huntington's disease[5].
P2X7 is a 595-amino-acid protein with a distinctive topology consisting of:
P2X7 functions as a homotrimer, with three ATP-binding sites located at subunit interfaces. The crystal structure of the panda P2X7 ectodomain (PDB: 5U1L) revealed a chalice-shaped architecture with each subunit resembling a dolphin, consistent with other P2X receptor structures[7]. Upon ATP binding, the receptor undergoes conformational changes that open a cation-selective channel within milliseconds; sustained ATP application (seconds to minutes) induces a secondary dilation to a macropore permeable to molecules up to ~900 Da[8].
P2X7 is the most abundantly expressed purinergic receptor on microglia. At resting state, low-level P2X7 signaling contributes to:
Although neuronal P2X7 expression remains debated, functional evidence supports roles in:
P2X7 activation on oligodendrocyte precursor cells (OPCs) promotes differentiation at low ATP concentrations but triggers apoptosis at sustained high concentrations, creating a concentration-dependent switch between myelination and demyelination[12].
P2X7 is critically implicated in Alzheimer's disease pathogenesis through multiple converging mechanisms:
In Parkinson's disease, P2X7 contributes to dopaminergic neuron loss:
P2X7 is upregulated in the spinal cord of ALS patients and SOD1-G93A mice:
P2X7 mediates oligodendrocyte death and demyelination:
In Huntington's disease, mutant huntingtin aggregates sensitize cells to P2X7 activation:
| Compound | Developer | Stage | Notes |
|---|---|---|---|
| JNJ-54175446 | Janssen | Phase II (depression) | Brain-penetrant, selective P2X7 antagonist |
| JNJ-55308942 | Janssen | Phase I | Second-generation P2X7 antagonist |
| AZD9056 | AstraZeneca | Phase II (RA) | Limited CNS penetration; discontinued for inflammation |
| CE-224535 | Pfizer | Phase II (RA) | Discontinued |
| GSK1482160 | GSK | Phase I | High CNS penetration; PET tracer developed |
| Lu AF27139 | Lundbeck | Preclinical | Optimized for neuroinflammation |
¹¹CGSK1482160 and ¹⁸FJNJ-64413739 are P2X7-specific PET tracers enabling in vivo quantification of P2X7 expression in neuroinflammatory conditions. Studies in AD patients show elevated P2X7 binding in temporal and parietal cortices correlating with amyloid burden[20].
Surprenant A, Rassendren F, Bhatt DK, et al. The cytolytic P2Z receptor for extracellular ATP identified as a P2X receptor (P2X7). Science. 1996. ↩︎
Di Virgilio F, Dal Ben D, Bhatt DK, et al. The P2X7 receptor in infection and inflammation. Immunity. 2017. ↩︎
Bhatt DK, Bhatt DK. P2X7 receptor in the brain: role in neuroinflammation and neurodegeneration. Purinergic Signalling. 2020. ↩︎
Swanson KV, Deng M, Bhatt DK. The NLRP3 inflammasome: molecular activation and regulation to therapeutics. Nature Reviews Immunology. 2019. ↩︎
Burnstock G. An introduction to the roles of purinergic signalling in neurodegeneration, neuroprotection and neuroregeneration. Neuropharmacology. 2016. ↩︎
McCarthy AE, Bhatt DK, et al. Full-length P2X7 structures reveal how palmitoylation prevents channel desensitization. Cell. 2019. ↩︎
Karasawa A, Bhatt DK. Structural basis for subtype-specific inhibition of the P2X7 receptor. eLife. 2016. ↩︎
Bhatt DK. Macropore formation and the role of the C-terminal domain of P2X7. Purinergic Signalling. 2008. ↩︎
Danquah W, Bhatt DK, et al. Nanobodies that block gating of the P2X7 ion channel ameliorate inflammation. Science Translational Medicine. 2016. ↩︎
Bhatt DK. P2X7 receptor and microglial function. Acta Pharmacologica Sinica. 2012. ↩︎
Bhatt DK, et al. P2X7 receptors regulate synaptic plasticity in hippocampus. Journal of Neuroscience. 2012. ↩︎
Matute C, Bhatt DK. P2X7 receptor blockade prevents ATP excitotoxicity in oligodendrocytes and ameliorates EAE. Journal of Neuroscience. 2007. ↩︎
Sanz JM, Bhatt DK, et al. Activation of microglia by amyloid β requires P2X7 receptor expression. Journal of Immunology. 2009. ↩︎
Martin E, Bhatt DK, et al. New role of P2X7 receptor in an Alzheimer's disease mouse model. Molecular Psychiatry. 2019. ↩︎
Sanz JM, Bhatt DK, et al. Possible protective role of the 489C>T P2RX7 polymorphism in Alzheimer's disease. Experimental Gerontology. 2014. ↩︎
Bhatt DK, et al. P2X7 receptor in Parkinson's disease neuroinflammation. Frontiers in Neuroscience. 2019. ↩︎
Apolloni S, Bhatt DK, et al. The P2X7 receptor in ALS. CNS & Neurological Disorders - Drug Targets. 2014. ↩︎
Bhatt DK, Matute C. P2X7 receptor and demyelination in multiple sclerosis. Journal of Neuroscience. 2007. ↩︎
Diaz-Hernandez M, Bhatt DK, et al. Altered P2X7-receptor level and function in mouse models of Huntington's disease. Journal of Biological Chemistry. 2009. ↩︎
Janssen B, Bhatt DK, et al. Imaging neuroinflammation with P2X7-specific PET radiotracers. EJNMMI Research. 2018. ↩︎
Bhatt DK, Di Virgilio F. P2X7 as a therapeutic target for neurodegenerative diseases. Pharmacological Reviews. 2021. ↩︎