Functional differences between ATP‐gated human and rat P2X3 receptors are caused by critical residues of the intracellular C‐terminal domain

Abstract

J. Neurochem. (2012) 122, 557–567. Abstract ATP‐activated P2X3 receptors of sensory ganglion neurons contribute to pain transduction and are involved in chronic pain signaling. Although highly homologous (97%) in rat and human species, it is unclear whether P2X3 receptors have identical function. Studying human and rat P2X3 receptors expressed in patch‐clamped human embryonic kidney (HEK) cells, we investigated the role of non‐conserved tyrosine residues in the C‐terminal domain (rat tyrosine‐393 and human tyrosine‐376) as key determinants of receptor function. In comparison with rat P2X3 receptors, human P2X3 receptors were more expressed and produced larger responses with slower desensitization and faster recovery. In general, desensitization was closely related to peak current amplitude for rat and human receptors. Downsizing human receptor expression to the same level of the rat one still yielded larger responses retaining slower desensitization and faster recovery. Mutating phenylalanine‐376 into tyrosine in the rat receptor did not change current amplitude; yet, it retarded desensitization onset, demonstrating how this residue was important to functionally link these two receptor states. Conversely, removing tyrosine from position 376 strongly down‐regulated human receptor function. The different topology of tyrosine residues in the C‐terminal domain has contrasting functional consequences and is sufficient to account for species‐specific properties of this pain‐transducing channel.

P2X3 receptors and sensitization of autonomic reflexes

“…The homology of human and rat P2X3 receptors is high (97% similarity and 93% identity); it is the C-terminal region that possesses differences in the topology of tyrosine residues. Human P2X3 receptors produce relatively large responses with less desensitization compared to rat (Sundukova et al, 2012). Finally, a cross-species cellular expression of P2X2 and P2X3 receptor mRNA in dorsal root ganglia neurons in rat, monkey, and human revealed that P2X3 but not P2X2 was expressed in the primates (Serrano et al, 2012) supporting the notion that P2X3 receptors have a more dominant sensory role than P2X2 in humans.…”

B-Type Natriuretic Peptide-Induced Delayed Modulation of TRPV1 and P2X3 Receptors of Mouse Trigeminal Sensory Neurons

“…For biotinylation experiments, cells were incubated with 1 mg/ml EZ-Sulfo-NHS-LC-biotin (Pierce, Rockford, IL, USA) as previously described [39,60]. Pull-down of biotinylated proteins was obtained with Streptavidin agarose resin (Pierce) for 2 h at 4°C according to the manufacturer’s instructions.…”

2′,3′-O-Substituted ATP derivatives as potent antagonists of purinergic P2X3 receptors and potential analgesic agents

“…Currents were recorded from small/medium size mouse TG neurons (nociceptors that strongly express native P2X3 receptors [70]) as previously described [70,82] in whole cell voltage clamp configuration, at a holding potential of −65 mV after correction for liquid junction potential. Cells were continuously superfused at room temperature with control solution containing (in mM): 152 NaCl, 5 KCl, 1 MgCl 2 , 2 CaCl 2 , 10 glucose, 10 HEPES; pH 7.4 adjusted with NaOH.…”