Heterologous Expression and Patch-Clamp Recording of P2X Receptors in HEK293 Cells

P2 purinergic receptors at the heart of pathological left ventricular remodeling following acute myocardial infarction

Pathological left ventricular remodeling is a complex process following an acute myocardial infarction, leading to architectural disorganization of the cardiac tissue. This phenomenon is characterized by sterile inflammation and the exaggerated development of fibrotic tissue, which is noncontractile and poorly conductive, responsible for organ dysfunction and heart failure. At present, specific therapies are lacking for both prevention and treatment of this condition, and no biomarkers are currently validated to identify at-risk patients. Physiopathological understanding of this process is limited, probably due to the combination of the multicellular responses involved that are initially necessary for tissue healing but may be detrimental in the longer term. Current research focuses on understanding and modulating the inflammatory response, a key aspect of the tissue healing process. Inflammation is triggered by the release of inflammatory mediators from cardiomyocytes undergoing cell death in the context of ischemia-reperfusion injury. Among them, extracellular ATP is a strong mediator of inflammation through the activation of P2 purinergic receptors, regulating the behavior of all the cellular actors of the postmyocardial infarction response and impacting organ function and recovery. Rather than considering each cellular protagonist independently, this review provides an integrated overview of the inflammatory and tissue response to myocardial infarction by members of the P2 receptor family. Finally, it explores the possibility of reducing pathological left ventricular remodeling through the modulation of these receptors and their associated signaling pathways.

Role of purinoreceptors in the release of extracellular vesicles and consequences on immune response and cancer progression

Cell-to-cell communication is a major process for accommodating cell functioning to changes in the environments and to preserve tissue and organism homeostasis. It is achieved by different mechanisms characterized by the origin of the message, the molecular nature of the messenger, its speed of action and its reach. Purinergic signalling is a powerful mechanism initiated by extracellular nucleotides, such as ATP, acting on plasma membrane purinoreceptors. Purinergic signalling is tightly controlled in time and space by the action of ectonucleotidases. Recent studies have highlighted the critical role of purinergic signalling in controlling the generation, release and fate of extracellular vesicles and, in this way, mediating long-distance responses. Most of these discoveries have been made in immune and cancer cells. This review is aimed at establishing the current knowledge on the way which purinoreceptors control extracellular vesicle-mediated communications and consequences for recipient cells.

Pharmacological and genetic characterisation of the canine P2X4 receptor

BACKGROUND AND PURPOSE

P2X4 receptors are emerging therapeutic targets for treating chronic pain and cardiovascular disease. Dogs are well-recognised natural models of human disease, but information regarding P2X4 receptors in dogs is lacking. To aid the development and validation of P2X4 receptor ligands, we have characterised and compared canine and human P2X4 receptors.

EXPERIMENTAL APPROACH

Genomic DNA was extracted from whole blood samples from 101 randomly selected dogs and sequenced across the P2RX4 gene to identify potential missense variants. Recombinant canine and human P2X4 receptors tagged with Emerald GFP were expressed in 1321N1 and HEK293 cells and analysed by immunoblotting and confocal microscopy. In these cells, receptor pharmacology was characterised using nucleotide-induced Fura-2 AM measurements of intracellular Ca²⁺ and known P2X4 receptor antagonists. P2X4 receptor-mediated inward currents in HEK293 cells were assessed by automated patch clamp.

KEY RESULTS

No P2RX4 missense variants were identified in any canine samples. Canine and human P2X4 receptors were localised primarily to lysosomal compartments. ATP was the primary agonist of canine P2X4 receptors with near identical efficacy and potency at human receptors. 2'(3')-O-(4-benzoylbenzoyl)-ATP, but not ADP, was a partial agonist with reduced potency for canine P2X4 receptors compared to the human orthologues. Five antagonists inhibited canine P2X4 receptors, with 1-(2,6-dibromo-4-isopropyl-phenyl)-3-(3-pyridyl)urea displaying reduced sensitivity and potency at canine P2X4 receptors.

CONCLUSION AND IMPLICATIONS

P2X4 receptors are highly conserved across dog pedigrees and display expression patterns and pharmacological profiles similar to human receptors, supporting validation and use of therapeutic agents for P2X4 receptor-related disease onset and management in dogs and humans.