Dihydropyridines Potentiate ATP-Induced Currents Mediated by the Full-Length Human P2X5 Receptor

Abstract

The P2X5 receptor, an ATP-gated cation channel, is believed to be involved in tumor development, inflammatory bone loss and inflammasome activation after bacterial infection. Therefore, it is a worthwhile pharmacological target to treat the corresponding diseases, especially in minority populations that have a gene variant coding for functional homotrimeric P2X5 channels. Here, we investigated the effects of dihydropyridines on the human full-length P2X5 receptor (hP2X5FL) heterologously expressed in Xenopus oocytes using the two-microelectrode voltage clamp method. Agonist dependency, kinetics and permeation behavior, including Cl- permeability, were similar to hP2X5FL expressed in HEK293 or 1321N1 cells. Additionally, 1,4-dihydropyridines have been shown to interact with various other purinergic receptors, and we have examined them as potential hP2X5 modulators. Of seven commercially available and four newly synthesized dihydropyridines tested at hP2X5FL, only amlodipine exerted an inhibitory effect, but only at a high concentration of 300 µM. Isradipine and—even more—nimodipine stimulated ATP-induced currents in the low micromolar range. We conclude that common dihydropyridines or four new derivatives of amlodipine are not suitable as hP2X5 antagonists, but amlodipine might serve as a lead for future synthesis to increase its affinity. Furthermore, a side effect of nimodipine therapy could be a stimulatory effect on inflammatory processes.

Unveiling the Structure–Activity Relationships at the Orthosteric Binding Site of P2X Ion Channels: The Route to Selectivity

“…We are highly interested in human homotrimeric P2X1, P2X2, P2X3, P2X4, P2X7, and the heterotrimeric P2X2/3 receptors and the present SAR study focuses on these targets. The P2X5 and P2X6 receptors exist predominantly in the heterotrimeric form and are difficult to establish in a stable cell − and are therefore excluded from the current SAR study. The prepared and commercially available nucleotides were screened in Ca 2+ flux assays at P2X1, P2X2, P2X2/3, P2X3, P2X4, and P2X7 receptors.…”

“…Therefore, due to the rapid acyl transfer between the two vicinal alcohols, the regioisomeric mixtures of 2′-and 3′ esters were not separated and tested as mixtures. Four commercially available nucleotides with either differing stereochemistry at the 2′-O position (30) or introduction of substituents at the 2′-O position (27−29) were applied in the SAR evaluation as well (Table 4). The second set focused on commercially available ATP derivatives with modifications at the nucleobase at 2-, 8-, and N 6 -positions that enrich or reduce the electron density of the purine ring system.…”

1,4-Dihydropyridine: synthetic advances, medicinal and insecticidal properties

“…A stimulatory effect on inammatory processes may also be a side effect of nimodipine therapy (Scheme 6). 23 Using alkyne 1,4-DHPs 6a and substituted azides 6b for the synthesis of functionalized triazoles, Bijani et al (2022) described a copper-catalyzed azide-alkyne cyclization (CuAAC) reaction for the synthesis of a library of 1,4-DHP-based 1,2,3triazole derivatives 6 and assessed their cytotoxic potential on colorectal adenocarcinoma. The ndings suggested that the majority of these drugs exhibit substantial antiproliferative action, with IC 50 values ranging from 0.63 AE 0.05 to 5.68 AE 0.14 mM.…”

Rehabilitation of the P2X5 receptor: a re-evaluation of structure and function

“…Soon afterwards, the human exon 10 sequence was confirmed by a second research group when probing human genomic DNA with the exon 10 cDNA sequence for rP2X5 [14]. A full-length construct of human P2X5 was prepared for expression studies and the resultant full-length protein (444 aa subunit) assembled into a functional hP2X5 receptor [14, and then see [15][16][17][18]. However, the primary sequence of the full-length human P2X5 protein (hP2X5-fl) has never been listed in popular databases (such as Ensembl and Uni-portKB).…”

“…Of these cohorts, black Americans (7 of 10 subjects) express the full-length P2X5 protein whereas the other cohorts (white American, 46 of 46; middle Eastern ethnicity, 10 of 10; Chinese ethnicity, 10 of 10 subjects) express the truncated P2X5 protein (hP2X5A, hP2X5Δ 328−349 ). It has been argued that a single-nucleotide polymorphism (SNP) can occur at the 3′-splice site of exon 10 of the human P2X5 gene, replacing a critical thymidine (T) with a guanine (G) nucleobase [13][14][15][16]18]. The G-allele results in splice-skipping of exon 10, leading to truncated P2X5 subunits in those human cDNA samples tested so far (69 of 76 subjects; 91%) [15,16].…”