Disease relevance of P2rx1

• A role of the fast ATP-gated P2X1 cation channel in thrombosis of small arteries in vivo [1].
• The mortality of P2X1-/- mice in a model of systemic thromboembolism was reduced and the size of mural thrombi formed after a laser-induced vessel wall injury was decreased as compared with normal mice, whereas the time for complete thrombus removal was shortened [1].
• We have cloned mouse candidate cell death genes RP-2 and nedd2 and used Northern blot analysis to study their expression in a growth-factor-dependent cell line (FDC-P1) that can be induced to undergo apoptosis by growth factor withdrawal and in a thymoma line (ST4) that undergoes apoptosis when irradiated [2].

High impact information on P2rx1

• In P2X1-receptor-deficient mice, contraction of the vas deferens to sympathetic nerve stimulation is reduced by up to 60% and responses to P2X receptor agonists are abolished [3].
• The P2X1 receptor is a fast ATP-gated cation channel expressed in blood platelets, where its role has been difficult to assess due to its rapid desensitization and the lack of pharmacological tools [1].
• Given that two of the tumor clones, A149 and A166, are remarkably similar in amino acid and DNA sequence to H-2Lq and H-2Dq, respectively, we also examined the 1591 RP2 and GUS loci for evidence of polymorphism [4].
• Deletion analysis and heterologous promoter assay disclosed that the proximal promoter region from -75 to +16 was able to activate chloramphenicol acetyltransferase expression by cAMP, and indicated that the proximal promoter element from -75 to -47 (RP-2 element) overlapping the TATA-like region was able to confer cAMP responsiveness [5].
• In inbred mice (Mus domesticus), the concentrations of mRNAs encoded by RP2 undergo a 10- to 12-fold induction in response to testosterone; in other Mus species (e.g., Mus hortulanus and Mus caroli), induction ranges from none to about two- to fourfold [6].

Biological context of P2rx1

• Structure and chromosome location of the mouse P2X(1) purinoceptor gene (P2rx1) [7].
• Intravenous injection of 10 mg/kg NF449 into mice resulted in selective inhibition of the P2X1 receptor and decreased intravascular platelet aggregation in a model of systemic thromboembolism (35 +/- 4 versus 51 +/- 3%) (P = 0.0061; n = 10) but without prolongation of the bleeding time (106 +/- 16 versus 78 +/- 7 s; n = 10) (N.S.; P = 0.1209) [8].
• Cloning, tissue distribution and functional characterization of the chicken P2X1 receptor [9].
• Selective blockade of the P2X1 receptor with NF449 led to reduced collagen-induced aggregation, confirming a role of this receptor in platelet activation induced by collagen [8].
• The P2X1 receptor is a calcium channel that functions to potentiate agonist-induced platelet shape change, and its inhibition or loss has little if any effect on hemostasis [10].

Anatomical context of P2rx1

• ATP activates P2x-contracting and P2y-relaxing purinoceptors in the smooth muscle of mouse vas deferens [11].
• A study of P2X1 receptor function in murine megakaryocytes and human platelets reveals synergy with P2Y receptors [12].
• With conditions below thresholds for classical electroporation and apoptosis, nsPEF induced calcium release from intracellular stores and subsequent calcium influx through store-operated channels in the plasma membrane that mimicked purinergic receptor-mediated calcium mobilization [13].
• Contractile responses were reduced by > 80% in the ileum from P2x1 receptor-deficient mice. alpha,beta-meATP-evoked contractions were reduced by approximately 35% by TTX (1 microM) and were unaffected by atropine (10 microM) [14].
• Gel shift assay identified RU-1 element-binding factors in both 293 and HeLa cells, whereas 293 cell-dominant factors were shown to bind only to RP-2 element [15].

Associations of P2rx1 with chemical compounds

• A subpopulation of neurons (10-15%) were alpha,beta-methylene ATP (alpha,beta-meATP) sensitive, and in neurons from P2X1 receptor-deficient mice the alpha,beta-meATP response was reduced to 2% of all neurons, demonstrating a direct role for P2X1 subunits [16].
• Control alpha,beta-meATP responses were eliminated by high extracellular Ca(2+) and pH, indicating the presence of heteromeric channels incorporating the properties of P2X1 and P2X2 receptors [16].
• Other nucleotides tested, including beta, gamma-methylene-ATP and 2-methylthio-ATP, which are considered prototypic agonists for P2x and P2y receptors, respectively, were ineffective; in general, modifications in the ribose-triphosphate chain and substitution on the 2-position of the purines reduced the efficacy of nucleotides [17].
• Topical application of suramin (nonspecific ATP receptor antagonist), pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS) (P2X receptor antagonist), and 2',3'-O-(2,4,6-trinitrophenyl)adenosine 5'-triphosphate (TNP-ATP) (P2X1, P2X3, P2X2/3 antagonist) after barrier disruption accelerated the barrier repair [18].
• In platelets, the classical P2T receptor has now been resolved into three P2 receptor subtypes: the P2Y1, P2X1 and P2TAC receptors (the last of these, which is coupled to the inhibition of adenylate cyclase, is yet to be cloned) [19].

Other interactions of P2rx1

• We identified the expression of most of the purinergic receptor subtypes (A1, A2, P2X1, 3-7, P2Y1, 2, 4) mRNAs, analysed by the reverse transcriptase-polymerase chain reaction [20].
• RT-PCR analysis confirmed the mRNA expression of the P2Z/P2X7 receptor and the absence of P2X1 [21].
• The P2Y12 receptor appeared unable to activate the GTPase per se as also observed for the adenosine triphosphate receptor P2X1 [22].

Analytical, diagnostic and therapeutic context of P2rx1

• Immunofluorescence staining of the vas deferens with antibodies against P2X1 receptor showed a diffuse, grainy distribution over the entire membrane of each smooth muscle cell [23].
• Electrophoretic mobility shift assay and DNase I footprinting analysis demonstrated that novel nuclear factors in 293 cells interacted with the RP-2 element, and that cAMP increased the binding activity of these nuclear factors to the RP-2 element [5].
• With rat LH-RP-2 (rLH) used as the standard diluted in assay buffer, the LH ELISA had a sensitivity of 102 pg/ml and a 50% displacement point of 531 pg/ml [24].
• Modification of the mouse interstitial cell testosterone assay by the addition of 1.5 microM forskolin to the incubation medium has improved the sensitivity of this luteinizing hormone bioassay from approximately 100 to 3 pg/tube of NIH rLH RP-2 [25].

References