Periprosthetic osteolysis (OL) is a major long-term complication of the total hip arthroplasty (THA), which can result in aseptic loosening and revision surgery. Purinergic receptor P2X, ligand-gated ion channel 7 (P2RX7) is an important regulator of inflammation and bone turnover. We were therefore interested in whether functional variants of the P2RX7 gene may be associated with OL and risk of THA failure. A total of 205 unrelated Czech patients with cementless-type THA were stratified according to the severity of acetabular OL and revision of THA. Four "loss-of-function" P2RX7 single nucleotide polymorphisms (SNPs), namely Glu496Ala, Ile568Asn, Arg307Gln, and null allele (rs35933842), were genotyped by polymerase chain reaction with sequence-specific primers (PCR-SSP). No significant association of P2RX7 variants with severity of OL was observed. The carriers of rare variants P2RX7 568Asn, 307Gln and null allele, all causing complete loss of P2RX7 function, tended to be overrepresented among patients with THA revision (9.6%) by comparison with those with unrevised functional prosthesis (2.1%, p = 0.09). Furthermore, the carriage of the P2RX7 307Gln allele was associated with greater cumulative hazard of THA revision (p = 0.02). In this preliminary study, we could nominate but not clearly demonstrate rare P2RX7 loss-of-function variants being associated with THA failure. Investigation in large THA cohorts is therefore warranted.

• MeSH
• dospělí MeSH
• genetická predispozice k nemoci MeSH
• genotyp MeSH
• jednonukleotidový polymorfismus MeSH
• kyčelní protézy MeSH
• lidé středního věku MeSH
• lidé MeSH
• náhrada kyčelního kloubu MeSH
• osteolýza genetika   MeSH
• polymerázová řetězová reakce MeSH
• pooperační komplikace etiologie   MeSH
• purinergní receptory P2 genetika   MeSH
• purinergní receptory P2X7 MeSH
• reoperace MeSH
• selhání protézy MeSH
• studie případů a kontrol MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The functional relevance of aromatic residues in the upper part of the transmembrane domain-1 of purinergic P2X receptors (P2XRs) was examined. Replacement of the conserved Tyr residue with Ala had a receptor-specific effect: the P2X1R was non-functional, the P2X2R, P2X4R, and P2X3R exhibited enhanced sensitivity to ATP and alphabeta-meATP accompanied by prolonged decay of current after washout of agonists, and the P2X7R sensitivity for agonists was not affected, though decay of current was delayed. The replacement of the P2X4R-Tyr42 with other amino acids revealed the relevance of an aromatic residue at this position. Mutation of the neighboring Phe and ipsilateral Tyr/Trp residues, but not the contralateral Phe residue, also affected the P2X2R, P2X3R, and P2X4R function. Double mutation of ipsilateral Tyr42 and Trp46 P2X4R residues restored receptor function, whereas the corresponding P2X2R double mutant was not functional. In contrast, mutation of the contralateral Phe48 residue in the P2X4R-Y42A mutant had no effect. These results indicate that aromatic residues in the upper part of TM1 play important roles in the three-dimensional structure of the P2XRs and that they are required not only for ion conductivity but also for specificity of agonist binding and/or channel gating.

• MeSH
• adenosintrifosfát analogy a deriváty   farmakologie   MeSH
• aminokyseliny aromatické genetika   metabolismus   MeSH
• biofyzika MeSH
• elektrická stimulace MeSH
• financování organizované MeSH
• konformace proteinů MeSH
• lidé MeSH
• membránové potenciály genetika   účinky léků   MeSH
• metoda terčíkového zámku metody   MeSH
• mutageneze genetika   MeSH
• purinergní receptory P2 genetika   klasifikace   metabolismus   MeSH
• sekvence aminokyselin MeSH
• signální transdukce fyziologie   účinky léků   MeSH
• terciární struktura proteinů genetika   fyziologie   MeSH
• transfekce metody   MeSH
• transformované buněčné linie MeSH
• vazba proteinů fyziologie   genetika   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zelené fluorescenční proteiny MeSH
• Check Tag
• lidé MeSH

Ivermectin (IVM), a large macrocyclic lactone, specifically enhances P2X(4) receptor-channel function by interacting with residues of transmembrane (TM) helices in the open conformation state. In this paper, we used cysteine-scanning mutagenesis of rat P2X(4)-TMs to identify and map residues of potential importance for channel gating and interaction with IVM. The receptor function was unchanged by mutations in 29 different residues, and among them, the IVM effects were altered in Gln(36), Leu(40), Val(43), Val(47), Trp(50), Asn(338), Gly(342), Leu(346), Ala(349), and Ile(356) mutants. The substitution-sensitive Arg(33) and Cys(353) mutants could also be considered as IVM-sensitive hits. The pattern of these 12 residues was consistent with helical topology of both TMs, with every third or fourth amino acid affected by substitution. These predominantly hydrophobic-nonpolar residues are also present in the IVM-sensitive Schistosoma mansoni P2X subunit. They lie on the same side of their helices and could face lipids in the open conformation state and provide the binding pocket for IVM. In contrast, the IVM-independent hits Met(31), Tyr(42), Gly(45), Val(49), Gly(340), Leu(343), Ala(344), Gly(347), Thr(350), Asp(354), and Val(357) map on the opposite side of their helices, probably facing the pore of receptor or protein and playing important roles in gating.

• MeSH
• antiparazitární látky metabolismus   MeSH
• buněčné linie MeSH
• financování organizované MeSH
• gating iontového kanálu MeSH
• ivermektin metabolismus   MeSH
• konformace proteinů MeSH
• krysa rodu rattus MeSH
• lidé MeSH
• metoda terčíkového zámku MeSH
• molekulární modely MeSH
• molekulární sekvence - údaje MeSH
• mutace MeSH
• purinergní receptory P2 genetika   chemie   metabolismus   MeSH
• purinergní receptory P2X4 MeSH
• sekvence aminokyselin MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• lidé MeSH
• zvířata MeSH