Pharmacology and Therapeutics - Research Publications
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ItemEditorial: Neuronal Co-transmission(FRONTIERS MEDIA SA, 2019-03-26)
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ItemUnlocking the Potential of Purinergic Signaling in Transplantation(WILEY, 2016-10)Purinergic signaling has been recognized as playing an important role in inflammation, angiogenesis, malignancy, diabetes and neural transmission. Activation of signaling pathways downstream from purinergic receptors may also be implicated in transplantation and related vascular injury. Following transplantation, the proinflammatory "danger signal" adenosine triphosphate (ATP) is released from damaged cells and promotes proliferation and activation of a variety of immune cells. Targeting purinergic signaling pathways may promote immunosuppression and ameliorate inflammation. Under pathophysiological conditions, nucleotide-scavenging ectonucleotidases CD39 and CD73 hydrolyze ATP, ultimately, to the anti-inflammatory mediator adenosine. Adenosine suppresses proinflammatory cytokine production and is associated with improved graft survival and decreased severity of graft-versus-host disease. Furthermore, purinergic signaling is involved both directly and indirectly in the mechanism of action of several existing immunosuppressive drugs, such as calcineurin inhibitors and mammalian target of rapamycin inhibitors. Targeting of purinergic receptor pathways, particularly in the setting of combination therapies, could become a valuable immunosuppressive strategy in transplantation. This review focuses on the role of the purinergic signaling pathway in transplantation and immunosuppression and explores possible future applications in clinical practice.
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ItemTHE CONCISE GUIDE TO PHARMACOLOGY 2017/18: Overview.(Wiley, 2017-12)The Concise Guide to PHARMACOLOGY 2017/18 is the third in this series of biennial publications. This version provides concise overviews of the key properties of nearly 1800 human drug targets with an emphasis on selective pharmacology (where available), plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. Although the Concise Guide represents approximately 400 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.13882/full. In addition to this overview, in which are identified 'Other protein targets' which fall outside of the subsequent categorisation, there are eight areas of focus: G protein-coupled receptors, ligand-gated ion channels, voltage-gated ion channels, other ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2017, and supersedes data presented in the 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature Committee of the Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.
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ItemThe potential of P2X7 receptors as a therapeutic target, including inflammation and tumour progression(SPRINGER, 2018-03)Seven P2X ion channel nucleotide receptor subtypes have been cloned and characterised. P2X7 receptors (P2X7R) are unusual in that there are extra amino acids in the intracellular C terminus. Low concentrations of ATP open cation channels sometimes leading to cell proliferation, whereas high concentrations of ATP open large pores that release inflammatory cytokines and can lead to apoptotic cell death. Since many diseases involve inflammation and immune responses, and the P2X7R regulates inflammation, there has been recent interest in the pathophysiological roles of P2X7R and the potential of P2X7R antagonists to treat a variety of diseases. These include neurodegenerative diseases, psychiatric disorders, epilepsy and a number of diseases of peripheral organs, including the cardiovascular, airways, kidney, liver, bladder, skin and musculoskeletal. The potential of P2X7R drugs to treat tumour progression is discussed.
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ItemPurinergic signalling and diabetes(SPRINGER, 2013-09)The pancreas is an organ with a central role in nutrient breakdown, nutrient sensing and release of hormones regulating whole body nutrient homeostasis. In diabetes mellitus, the balance is broken-cells can be starving in the midst of plenty. There are indications that the incidence of diabetes type 1 and 2, and possibly pancreatogenic diabetes, is rising globally. Events leading to insulin secretion and action are complex, but there is emerging evidence that intracellular nucleotides and nucleotides are not only important as intracellular energy molecules but also as extracellular signalling molecules in purinergic signalling cascades. This signalling takes place at the level of the pancreas, where the close apposition of various cells-endocrine, exocrine, stromal and immune cells-contributes to the integrated function. Following an introduction to diabetes, the pancreas and purinergic signalling, we will focus on the role of purinergic signalling and its changes associated with diabetes in the pancreas and selected tissues/organ systems affected by hyperglycaemia and other stress molecules of diabetes. Since this is the first review of this kind, a comprehensive historical angle is taken, and common and divergent roles of receptors for nucleotides and nucleosides in different organ systems will be given. This integrated picture will aid our understanding of the challenges of the potential and currently used drugs targeted to specific organ/cells or disorders associated with diabetes.
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ItemNo Preview AvailablePurinergic receptors are part of a signalling system for proliferation and differentiation in distinct cell lineages in human anagen hair follicles(SPRINGER, 2008-12)We investigated the expression of P2X(5), P2X(7), P2Y(1) and P2Y(2) receptor subtypes in adult human anagen hair follicles and in relation to markers of proliferation [proliferating cell nuclear antigen (PCNA) and Ki-67], keratinocyte differentiation (involucrin) and apoptosis (anticaspase-3). Using immunohistochemistry, we showed that P2X(5), P2Y(1) and P2Y(2) receptors were expressed in spatially distinct zones of the anagen hair follicle: P2Y(1) receptors in the outer root sheath and bulb, P2X(5) receptors in the inner and outer root sheaths and medulla and P2Y(2) receptors in living cells at the edge of the cortex/medulla. P2X(7) receptors were not expressed. Colocalisation experiments suggested different functional roles for these receptors: P2Y(1) receptors were associated with bulb and outer root sheath keratinocyte proliferation, P2X(5) receptors were associated with differentiation of cells of the medulla and inner root sheaths and P2Y(2) receptors were associated with early differentiated cells in the cortex/medulla that contribute to the formation of the hair shaft. The therapeutic potential of purinergic agonists and antagonists for controlling hair growth is discussed.
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ItemNo Preview AvailableATP signalling in epilepsy(SPRINGER, 2008-12)This paper focuses on a role for ATP neurotransmission and gliotransmission in the pathophysiology of epileptic seizures. ATP along with gap junctions propagates the glial calcium wave, which is an extraneuronal signalling pathway in the central nervous system. Recently astrocyte intercellular calcium waves have been shown to underlie seizures, and conventional antiepileptic drugs have been shown to attenuate these calcium waves. Blocking ATP-mediated gliotransmission, therefore, represents a potential target for antiepileptic drugs. Furthermore, while knowledge of an antiepileptic role for adenosine is not new, a recent study showed that adenosine accumulates from the hydrolysis of accumulated ATP released by astrocytes and is believed to inhibit distant synapses by acting on adenosine receptors. Such a mechanism is consistent with a surround-inhibitory mechanism whose failure would predispose to seizures. Other potential roles for ATP signalling in the initiation and spread of epileptiform discharges may involve synaptic plasticity and coordination of synaptic networks. We conclude by making speculations about future developments.
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ItemNo Preview AvailableATP release from the human ureter on distension and P2X3 receptor expression on suburothelial sensory nerves(SPRINGER, 2008-12)It is not clear how the increase in intraluminal pressure behind an obstructing ureteric calculus causes an increase in action potential frequency in ureteric sensory nerves so the pain messages are transmitted to the brain. It has been proposed that ureteric distension causes urothelial release of ATP, which activates purinoceptors on suburothelial nociceptive sensory nerves. The purpose of this study was to determine whether distension of the human ureter results in the release of ATP and whether the nociceptive P2 receptor, P2X(3), is expressed on suburothelial sensory nerves in the human ureter. Human ureter segments were perfused with Krebs solution and intermittently distended to a range of pressures. Samples of perfusate were collected throughout and the ATP concentration ([ATP]) was determined using a luciferin-luciferase assay. Sections of ureter were stained using antibodies against P2X(3) and capsaicin receptors (TRPV1). [ATP] rose to more than 10 times baseline levels after distension beyond a threshold of 25-30 cmH(2)O. Immunofluorescence studies on consecutive frozen sections showed that suburothelial nerves stained positively for P2X(3) and capsaicin receptors, with no staining in controls. These findings are consistent with the hypothesis that purinergic signalling is involved in human ureteric mechanosensory transduction, leading to nociception.
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ItemNo Preview AvailableErratum to: P2X(5) and P2X (7) receptors in human warts and CIN 612 organotypic raft cultures of human papillomavirus infected keratinocytes.(Springer Science and Business Media LLC, 2006-11)
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ItemNo Preview AvailableP2X(5) and P2X(7) receptors in human warts and CIN-612 organotypic raft cultures of human papillomavirus infected keratinocytes.(Springer Science and Business Media LLC, 2006-09)Purinergic receptors, which bind adenosine 5'-triphosphate (ATP), are expressed on human cutaneous keratinocytes and in squamous cell carcinomas. Studies on normal human epidermis and primary keratinocyte cultures have suggested that P2X(5) receptors are likely to be involved in keratinocyte differentiation and P2X(7) receptors are likely to be part of the machinery of end stage terminal differentiation/apoptosis of keratinocytes. P2X(7) receptor agonists can significantly reduce primary keratinocyte cell numbers in culture. Human papillomaviruses are increasingly recognised as important human carcinogens in the development of non-melanoma skin cancers. In our study, immunohistochemical analysis for P2X(5) and P2X(7) receptors was performed on paraffin sections of normal human skin, warts, raft cultures of normal human keratinocytes and raft cultures of CIN 612 cells, a model of keratinocytes infected with human papillomavirus type 31. In warts there was up-regulation of the expression of P2X(5) receptors. A similar pattern was seen in the CIN 612 raft cultures. Both P2X(5) and P2X(7) receptors were found in the nuclei of koilocytes, abnormal keratinocytes characteristic of human papillomavirus infection. P2X(5) and P2X(7) receptors may provide a new focus for therapeutic research into treatments for warts because these receptors can induce cell differentiation and cell death.