Disease relevance of P2rx4

• Short-term hyperthyroidism modulates the fat-cell adenylate cyclase system at the receptor level (beta-receptor number increased, R-site purinergic-receptor number decreased) and the catalytic subunit of adenylate cyclase [1].
• Here we report an immunohistochemical analysis of P2X4 receptor (P2X4R), an ATP-gated ion channel, expression in rat C6 glioma model [2].
• Its effect on phospholipase C seems to be mediated by a purinergic receptor coupled to the intracellular effector via a pertussis toxin-sensitive G protein [3].
• Lesional accumulation of P2X4 receptor+ monocytes following experimental traumatic brain injury [4].
• Simultaneously with glia activation, hyperalgesia was observed, but the expression of P2X4 receptor, which is considered to be closely associated with hyperalgesia, on microglia was not detected [5].

High impact information on P2rx4

• We also found RNA for (P2X1)(ref. 7), (P2X2)(ref. 8) and P2X4 (ref. 9) in sensory neurons; channels expressed from individual cDNAs did not reproduce those of sensory ganglia [6].
• P2X4 RNA is found by in situ hybridization in the brain, peripheral ganglia and epithelia including serosal cells of salivary glands [7].
• In situ hybridization reveals the expression of P2X4 mRNA in central nervous system neurons [8].
• Northern blot and reverse transcription-PCR (RT-PCR) analysis demonstrate a wide distribution of P2X4 transcripts in various tissues, including blood vessels and leukocytes [8].
• This suggests that the P2X4 receptor might mediate not only ATP-dependent synaptic transmission in the central nervous system but also a wide repertoire of biological responses in diverse tissues [8].

Biological context of P2rx4

• To identify regions that undergo rearrangement during gating and to probe their secondary structure, we performed tryptophan scanning mutagenesis on the two putative TMs of the rat P2X4 receptor channel [9].
• Northern analysis confirmed upregulation of three of these genes, PAI-1, P2X4, and P15INK4B [10].
• In contrast to these effects on P2X4 receptors, cibacron blue inhibited the ATP-induced response in both single cells and rafts of HEK293 cells expressing the P2X2 receptor (IC50 approximately 600-800 nM) [11].
• In particular, P2X2 and P2X4 proteins became significantly up-regulated, although to different extent and in different cellular phenotypes [12].
• It is speculated that P2X7 receptors may be involved in programmed cell death during embryogenesis and that P2X4, P2X(5) and P2X6 receptors might be involved in postnatal neurogenesis [13].

Anatomical context of P2rx4

• Spinal cord injury induces early and persistent lesional P2X4 receptor expression [14].
• Recently, glial P2X4 receptor (P2X4R) has been identified as a major contributor to the development of neuropathic pain after peripheral nerve injury [14].
• In cholangiocyte lysates, P2X4 protein was readily detected, and immunohistochemical staining of intact rat liver revealed P2X4 protein concentrated in intrahepatic bile ducts [15].
• P2X4 receptors induced in spinal microglia gate tactile allodynia after nerve injury [16].
• By antibody-labeling of surface receptors in living neurons, we showed that P2X4 receptors undergo rapid constitutive internalization and subsequent reinsertion into the plasma membrane, whereas P2X2 receptors were not regulated in such a way [17].

Associations of P2rx4 with chemical compounds

• Histidine 140 plays a key role in the inhibitory modulation of the P2X4 nucleotide receptor by copper but not zinc [18].
• P2X receptors acted presynaptically to enhance the release of glutamate, suggesting that the regulated cycling of P2X4-containing receptors might provide a mechanism for modulation of synaptic transmission [17].
• P2X6 receptors, like P2X4, receptors, are not blocked by the antagonists suramin and pyridoxal-5-phosphate-6-azophenyl-2',4'-disulfonic acid [19].
• The in vitro studies of organotypic cultures from hippocampus evidenced that P2X2 and P2X4 were up-regulated by glucose/oxygen deprivation [12].
• The order of their potencies was ATP >> 2-MeSATP > or = ADP > adenosine > AMP, corresponding to a P2 purinergic receptor [20].

Other interactions of P2rx4

• Due to lack of any known antagonist for P2X4 it is unlikely that native P2X4 has previously been recognized as a P2X purinoceptor [21].
• P2X4, P2Y2 and 4 receptor mRNA colocalisation studies combining in situ hybridisation and immunohistochemistry were also carried out [22].
• Almost all the microglial cells that were positive for the marker ED1, expressed P2X1 and P2X4 receptors, whereas only about 30% of the cells with ED1-immunoreactivity were found to express the P2X7 receptor [23].
• 3. In situ hybridization histochemistry for P2X3 and P2X4 receptor mRNAs showed that both mRNAs were expressed throughout the SON and in the paraventricular nucleus (PVN) [24].
• Granular and microglial cells were labeled for P2X5 (weakly) and P2X4 receptors, respectively [25].

Analytical, diagnostic and therapeutic context of P2rx4

• Immunocytochemistry showed strong P2X4 receptor expression partly associated with the membrane, weak P2X7 staining that was not associated with the cell membrane, and no P2X1 receptor immunoreactivity [26].
• Intense P2X4 immunofluorescence was localized to microglia cells [12].
• METHODS: The effects of ethanol (25-200 mM +/- ATP) on rat recombinant homomeric P2X2 and P2X4 receptors expressed in Xenopus oocytes were tested by using two-electrode voltage clamp techniques [27].
• The protein was identified by Western blotting in membrane extracts of these tissues, and the ectodomain antibody immunoprecipitated a protein that was recognised with a P2X4 receptor C terminus antibody [28].

References