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Sluyter R, Sophocleous RA, Stokes L. P2X receptors: Insights from the study of the domestic dog. Neuropharmacology 2023; 224:109358. [PMID: 36464207 DOI: 10.1016/j.neuropharm.2022.109358] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 11/23/2022] [Accepted: 11/28/2022] [Indexed: 12/03/2022]
Abstract
Fifty years ago, the late Geoffrey Burnstock described the concept of purinergic nerves and transmission bringing into existence the broader concepts of purinergic signaling including P2X receptors. These receptors are trimeric ligand-gated cation channels activated by extracellular adenosine 5'-triphosphate (ATP). P2X receptors have important roles in health and disease and continue to gain interest as potential therapeutic targets in inflammatory, neurological, cardiovascular and many other disorders including cancer. Current understanding of P2X receptors has largely arisen from the study of these receptors in humans and rodents, but additional insights have been obtained from the study of P2X receptors in the domestic dog, Canis familiaris. This review article will briefly introduce purinergic signaling and P2X receptors, before detailing the pharmacological profiles of the two recombinant canine P2X receptors studied to date, P2X7 and P2X4. The article will then describe the current state of knowledge concerning the distribution and function of the P2X receptor family in dogs. The article will also discuss the characterization of single nucleotide polymorphisms in the canine P2RX7 gene, and contrast this variation to the canine P2RX4 gene, which is largely conserved between dogs. Finally, this article will outline published examples of the use of dogs to study the pharmacokinetics of P2X7 and P2X3 antagonists, and how they have contributed to the preclinical testing of antagonists to human P2X7, CE-224,535, and human P2X3, Gefapixant (AF-219, MK-7264) and Eliapixant (BAY, 1817080), with Gefapixant gaining recent approval for use in the treatment of refractory chronic cough in humans. This article is part of the Special Issue on 'Purinergic Signaling: 50 years'.
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Affiliation(s)
- Ronald Sluyter
- Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia; Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia.
| | - Reece A Sophocleous
- Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia; Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Leanne Stokes
- School of Pharmacy, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK
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Papadopoulos C, Anagnostopoulos K, Tsiptsios D, Karatzetzou S, Liaptsi E, Lazaridou IZ, Kokkotis C, Makri E, Ioannidou M, Aggelousis N, Vadikolias K. Unexplored Roles of Erythrocytes in Atherothrombotic Stroke. Neurol Int 2023; 15:124-139. [PMID: 36810466 PMCID: PMC9944955 DOI: 10.3390/neurolint15010011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 01/16/2023] [Accepted: 01/19/2023] [Indexed: 01/25/2023] Open
Abstract
Stroke constitutes the second highest cause of morbidity and mortality worldwide while also impacting the world economy, triggering substantial financial burden in national health systems. High levels of blood glucose, homocysteine, and cholesterol are causative factors for atherothrombosis. These molecules induce erythrocyte dysfunction, which can culminate in atherosclerosis, thrombosis, thrombus stabilization, and post-stroke hypoxia. Glucose, toxic lipids, and homocysteine result in erythrocyte oxidative stress. This leads to phosphatidylserine exposure, promoting phagocytosis. Phagocytosis by endothelial cells, intraplaque macrophages, and vascular smooth muscle cells contribute to the expansion of the atherosclerotic plaque. In addition, oxidative stress-induced erythrocytes and endothelial cell arginase upregulation limit the pool for nitric oxide synthesis, leading to endothelial activation. Increased arginase activity may also lead to the formation of polyamines, which limit the deformability of red blood cells, hence facilitating erythrophagocytosis. Erythrocytes can also participate in the activation of platelets through the release of ADP and ATP and the activation of death receptors and pro-thrombin. Damaged erythrocytes can also associate with neutrophil extracellular traps and subsequently activate T lymphocytes. In addition, reduced levels of CD47 protein in the surface of red blood cells can also lead to erythrophagocytosis and a reduced association with fibrinogen. In the ischemic tissue, impaired erythrocyte 2,3 biphosphoglycerate, because of obesity or aging, can also favor hypoxic brain inflammation, while the release of damage molecules can lead to further erythrocyte dysfunction and death.
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Affiliation(s)
- Charalampos Papadopoulos
- Laboratory of Biochemistry, Department of Medicine, Democritus University of Thrace, 68100 Alexandroupolis, Greece
| | - Konstantinos Anagnostopoulos
- Laboratory of Biochemistry, Department of Medicine, Democritus University of Thrace, 68100 Alexandroupolis, Greece
| | - Dimitrios Tsiptsios
- Department of Neurology, Democritus University of Thrace, 68100 Alexandroupolis, Greece
- Correspondence:
| | - Stella Karatzetzou
- Department of Neurology, Democritus University of Thrace, 68100 Alexandroupolis, Greece
| | - Eirini Liaptsi
- Department of Neurology, Democritus University of Thrace, 68100 Alexandroupolis, Greece
| | | | - Christos Kokkotis
- Department of Physical Education and Sport Science, Democritus University of Thrace, 69100 Komotini, Greece
| | - Evangelia Makri
- Department of Physical Education and Sport Science, Democritus University of Thrace, 69100 Komotini, Greece
| | - Maria Ioannidou
- Department of Physical Education and Sport Science, Democritus University of Thrace, 69100 Komotini, Greece
| | - Nikolaos Aggelousis
- Department of Physical Education and Sport Science, Democritus University of Thrace, 69100 Komotini, Greece
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Sophocleous RA, Sluyter V, Curtis BL, Curtis SJ, Jurak LM, Faulks M, Spildrejorde M, Gates S, Proctor EJ, Seavers A, Watson D, Kuit T, Dowton M, Stokes L, Sluyter R. Association of a P2RX7 gene missense variant with brachycephalic dog breeds. Anim Genet 2019; 51:127-131. [PMID: 31774195 DOI: 10.1111/age.12884] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2019] [Indexed: 12/16/2022]
Abstract
Missense variants are associated with various phenotypic traits and disorders in dogs. The canine P2RX7 gene, coding the ATP-gated P2X7 receptor ion channel, contains four known missense variants. The current study aimed to examine the presence of these variants in a random sample of pedigree and mixed-pedigree dogs. Exons 3, 8, 11 and 13 of the P2RX7 gene, encoding these four respective variants, in 65 dogs were assessed by Sanger sequencing and combined with existing sequencing data from another 69 dogs. The distribution of these variants was then evaluated in all 134 dogs combined and separately within individual breeds including 35 different pure breeds. The rs23314713 (p.Phe103Leu) and rs23315462 (p.Pro452Ser) variants were present in 47 and 40% of all dogs studied respectively, with the rs23314713 variant associated with brachycephalic breeds. Among pedigree dogs, the rs23314713 and rs23315462 variants were associated with brachycephalic and non-brachycephalic breeds respectively. The rs851148233 (p.Arg270Cys) and rs850760787 (p.Arg365Gln) variants were present only in dogs of Cocker Spaniel and Labrador Retriever pedigrees respectively. No other missense variants were found in exons 3, 8, 11 and 13 of the P2RX7 gene within the dogs. In conclusion, the rs23314713 and rs23315462 missense variants of the P2RX7 gene are present in a large proportion of dogs, with the rs23314713 variant associated with a number of brachycephalic breeds. However, the association of this variant with dogs of bulldog ancestry, not brachycephaly per se, cannot be excluded.
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Affiliation(s)
- R A Sophocleous
- Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.,Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - V Sluyter
- Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.,Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - B L Curtis
- Albion Park Veterinary Hospital, Albion Park, NSW, 2527, Australia
| | - S J Curtis
- Albion Park Veterinary Hospital, Albion Park, NSW, 2527, Australia
| | - L M Jurak
- Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.,Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - M Faulks
- Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.,Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - M Spildrejorde
- Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.,Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - S Gates
- Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.,Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - E-J Proctor
- Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.,Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - A Seavers
- Oak Flats Veterinary Clinic, Oak Flats, NSW, 2529, Australia
| | - D Watson
- Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.,Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - T Kuit
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - M Dowton
- Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.,Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - L Stokes
- School of Pharmacy, University of East Anglia, Norwich, NR4 7TJ, UK
| | - R Sluyter
- Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.,Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
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Bartlett R, Stokes L, Curtis SJ, Curtis BL, Sluyter R. Probenecid directly impairs activation of the canine P2X7 receptor. Nucleosides Nucleotides Nucleic Acids 2017; 36:736-744. [PMID: 29200326 DOI: 10.1080/15257770.2017.1391395] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The current study aimed to determine if probenecid could directly impair the canine P2X7 receptor, a ligand-gated cation channel activated by extracellular adenosine 5'-triphosphate (ATP). Patch clamp measurements demonstrated that probenecid impairs ATP-induced inward currents in HEK-293 cells expressing canine P2X7. Flow cytometric measurements of ethidium+ uptake into HEK-293 cells expressing canine P2X7 showed that probenecid impairs ATP-induced pore formation in a concentration-dependent manner, with a half maximal inhibitory concentration of 158 µM. Finally, ELISA measurements revealed that probenecid impairs ATP-induced interleukin-1β release in dog blood. In conclusion, this study reveals that probenecid can directly impair canine P2X7 activation.
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Affiliation(s)
- Rachael Bartlett
- a School of Biological Sciences, University of Wollongong , Wollongong , NSW , Australia.,b Centre for Medical and Molecular Bioscience, University of Wollongong , Wollongong , NSW , Australia.,c Illawarra Health and Medical Research Institute , Wollongong , NSW , Australia
| | - Leanne Stokes
- d School of Pharmacy, University of East Anglia , Norwich , United Kingdom
| | - Stephen J Curtis
- e Albion Park Veterinary Hospital , Albion Park , NSW , Australia
| | - Belinda L Curtis
- e Albion Park Veterinary Hospital , Albion Park , NSW , Australia
| | - Ronald Sluyter
- a School of Biological Sciences, University of Wollongong , Wollongong , NSW , Australia.,b Centre for Medical and Molecular Bioscience, University of Wollongong , Wollongong , NSW , Australia.,c Illawarra Health and Medical Research Institute , Wollongong , NSW , Australia
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Abstract
The P2X7 receptor is a trimeric ion channel gated by extracellular adenosine 5'-triphosphate. The receptor is present on an increasing number of different cells types including stem, blood, glial, neural, ocular, bone, dental, exocrine, endothelial, muscle, renal and skin cells. The P2X7 receptor induces various downstream events in a cell-specific manner, including inflammatory molecule release, cell proliferation and death, metabolic events, and phagocytosis. As such this receptor plays important roles in heath and disease. Increasing knowledge about the P2X7 receptor has been gained from studies of, but not limited to, protein chemistry including cloning, site-directed mutagenesis, crystal structures and atomic modeling, as well as from studies of primary tissues and transgenic mice. This chapter focuses on the P2X7 receptor itself. This includes the P2RX7 gene and its products including splice and polymorphic variants. This chapter also reviews modulators of P2X7 receptor activation and inhibition, as well as the transcriptional regulation of the P2RX7 gene via its promoter and enhancer regions, and by microRNA and long-coding RNA. Furthermore, this chapter discusses the post-translational modification of the P2X7 receptor by N-linked glycosylation, adenosine 5'-diphosphate ribosylation and palmitoylation. Finally, this chapter reviews interaction partners of the P2X7 receptor, and its cellular localisation and trafficking within cells.
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Affiliation(s)
- Ronald Sluyter
- School of Biological Sciences, University of Wollongong, Wollongong, NSW, 2522, Australia. .,Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia. .,Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.
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