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Cloning and characterization of a P2X receptor expressed in the central nervous system of Lymnaea stagnalis

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posted on 2013-06-12, 14:58 authored by Selvan Bavan, Volko A. Straub, Tania E. Webb, Steven J. Ennion
P2X receptors are membrane ion channels gated by extracellular ATP. Mammals possess seven distinct P2X subtypes (P2X1-7) that have important functions in a wide array of physiological processes including roles in the central nervous system (CNS) where they have been linked to modulation of neurotransmitter release. We report here the cloning and functional characterization of a P2X receptor from the mollusc Lymnaea stagnalis. This model organism has a relatively simple CNS consisting of large readily identifiable neurones, a feature which together with a well characterized neuronal circuitry for important physiological processes such as feeding and respiration makes it an attractive potential model to examine P2X function. Using CODEHOP PCR we identified a single P2X receptor (LymP2X) in Lymnaea CNS which was subsequently cloned by RT-PCR. When heterologously expressed in Xenopus oocytes, LymP2X exhibited ATP evoked inward currents (EC(50) 6.2 µM) which decayed during the continued presence of agonist. UTP and ADP did not activate the receptor whereas αβmeATP was a weak agonist. BzATP was a partial agonist with an EC(50) of 2.4 µM and a maximal response 33% smaller than that of ATP. The general P2 receptor antagonists PPADS and suramin both inhibited LymP2X currents with IC(50) values of 8.1 and 27.4 µM respectively. LymP2X is inhibited by acidic pH whereas Zn(2+) and Cu(2+) ions exhibited a biphasic effect, potentiating currents up to 100 µM and inhibiting at higher concentrations. Quantitative RT-PCR and in situ hybridization detected expression of LymP2X mRNA in neurones of all CNS ganglia suggesting this ion channel may have widespread roles in Lymnaea CNS function.

Funding

SB was funded by a studentship from the Biotechnology and Biological Sciences Research Council (http://www.bbsrc.ac.uk/home/home.aspx). SJE was funded by project grant WT081601MA from the Wellcome Trust (http://www.wellcome.ac.uk/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

History

Citation

PLoS One, 2012, 7 (11), e50487

Author affiliation

/Organisation/COLLEGE OF MEDICINE, BIOLOGICAL SCIENCES AND PSYCHOLOGY/School of Biological Sciences/Department of Cell Physiology and Pharmacology

Version

  • VoR (Version of Record)

Published in

PLoS One

Publisher

Public Library of Science

issn

1932-6203

eissn

1932-6203

Copyright date

2012

Available date

2013-06-12

Publisher version

http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050487

Language

en