Two P2X1 receptor transcripts able to form functional channels are present in most human monocytes.
To characterize the presence and general properties of P2X1 receptors in single human monocytes we used RT-PCR, flow cytometry, and the patch-clamp and the two-electrode voltage-clamp techniques. Most human monocytes expressed the canonical P2X1 (90%) and its splicing variant P2X1del (88%) mRNAs. P2X1 receptor immunoreactivity was also observed in 70% of these cells. Currents mediated by P2X1 (EC50=1.9±0.8µm) and P2X1del (EC50>1000µm) channels, expressed in Xenopus leavis oocytes, have different ATP sensitivity and kinetics. Both currents mediated by P2X1 and P2X1del channels kept increasing during the continuous presence of high ATP concentrations. Currents mediated by the native P2X1 receptors in human monocytes showed an EC50=6.3±0.2µm. Currents have kinetics that resemble those observed for P2X1 and P2X1del receptors in oocytes. Our study is the first to demonstrate the expression of P2X1 transcript and its splicing variant P2X1del in most human monocytes. We also, for the first time, described functional homomeric P2X1del channels and demonstrated that currents mediated by P2X1 or P2X1del receptors, during heterologous expression, increased in amplitude when activated with high ATP concentrations in a similar fashion to those channels that increase their conductance under similar conditions, such as P2X7, P2X2, and P2X4 channels.
Instituto Potosino Investigación Científica y Tecnológica, Camino a la Presa San José 2055, Col. Lomas 4ª Sección, CP 78216, San Luis Potosí, México.
Cintya
C
López-López
Instituto Potosino Investigación Científica y Tecnológica, Camino a la Presa San José 2055, Col. Lomas 4ª Sección, CP 78216, San Luis Potosí, México.
Josue
J
Jaramillo-Polanco
Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, SLP, México.
Diana P
DP
Portales-Pérez
Instituto Potosino Investigación Científica y Tecnológica, Camino a la Presa San José 2055, Col. Lomas 4ª Sección, CP 78216, San Luis Potosí, México.
Karen S
KS
Gómez-Coronado
Instituto Potosino Investigación Científica y Tecnológica, Camino a la Presa San José 2055, Col. Lomas 4ª Sección, CP 78216, San Luis Potosí, México.
Jessica G
JG
Rodríguez-Meléndez
Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, SLP, México.
Juan D
JD
Cortés-García
Instituto Potosino Investigación Científica y Tecnológica, Camino a la Presa San José 2055, Col. Lomas 4ª Sección, CP 78216, San Luis Potosí, México.
Rosa
R
Espinosa-Luna
Departamento de Farmacología, Facultad de Medicina, Universidad Nacional Autónoma de México, México DF, México.
Luis M
LM
Montaño
Instituto Potosino Investigación Científica y Tecnológica, Camino a la Presa San José 2055, Col. Lomas 4ª Sección, CP 78216, San Luis Potosí, México. Electronic address: cbarajas@ipicyt.edu.mx.
Carlos
C
Barajas-López
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D055724:Electrophysiological Phenomena / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D058474:Receptors, Purinergic P2X1 / Q000235:genetics* / Q000378:metabolism*; D014982:Xenopus laevis
D020033:Protein Isoforms; D012333:RNA, Messenger; D058474:Receptors, Purinergic P2X1; D000255:Adenosine Triphosphate
Blood cells; Heterologous expression; P2X receptors; P2X1del receptors; Patch clamp