Cargando…

Bile acids inhibit human purinergic receptor P2X4 in a heterologous expression system

We recently demonstrated that bile acids, especially tauro-deoxycholic acid (t-DCA), modify the function of the acid-sensing ion channel ASIC1a and other members of the epithelial sodium channel (ENaC)/degenerin (DEG) ion channel family. Surprisingly, ASIC1 shares a high degree of structural similar...

Descripción completa

Detalles Bibliográficos
Autores principales: Ilyaskin, Alexandr V., Sure, Florian, Nesterov, Viatcheslav, Haerteis, Silke, Korbmacher, Christoph
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Rockefeller University Press 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6572003/
https://www.ncbi.nlm.nih.gov/pubmed/30988062
http://dx.doi.org/10.1085/jgp.201812291
_version_ 1783427540548845568
author Ilyaskin, Alexandr V.
Sure, Florian
Nesterov, Viatcheslav
Haerteis, Silke
Korbmacher, Christoph
author_facet Ilyaskin, Alexandr V.
Sure, Florian
Nesterov, Viatcheslav
Haerteis, Silke
Korbmacher, Christoph
author_sort Ilyaskin, Alexandr V.
collection PubMed
description We recently demonstrated that bile acids, especially tauro-deoxycholic acid (t-DCA), modify the function of the acid-sensing ion channel ASIC1a and other members of the epithelial sodium channel (ENaC)/degenerin (DEG) ion channel family. Surprisingly, ASIC1 shares a high degree of structural similarity with the purinergic receptor P2X4, a nonselective cation channel transiently activated by ATP. P2X4 is abundantly expressed in the apical membrane of bile duct epithelial cells and is therefore exposed to bile acids under physiological conditions. Here, we hypothesize that P2X4 may also be modulated by bile acids and investigate whether t-DCA and other common bile acids affect human P2X4 heterologously expressed in Xenopus laevis oocytes. We find that application of either t-DCA or unconjugated deoxycholic acid (DCA; 250 µM) causes a strong reduction (∼70%) of ATP-activated P2X4-mediated whole-cell currents. The inhibitory effect of 250 µM tauro-chenodeoxycholic acid is less pronounced (∼30%), and 250 µM chenodeoxycholic acid, cholic acid, or tauro-cholic acid did not significantly alter P2X4-mediated currents. t-DCA inhibits P2X4 in a concentration-dependent manner by reducing the efficacy of ATP without significantly changing its affinity. Single-channel patch-clamp recordings provide evidence that t-DCA inhibits P2X4 by stabilizing the channel’s closed state. Using site-directed mutagenesis, we identifiy several amino acid residues within the transmembrane domains of P2X4 that are critically involved in mediating the inhibitory effect of t-DCA on P2X4. Importantly, a W46A mutation converts the inhibitory effect of t-DCA into a stimulatory effect. We conclude that t-DCA directly interacts with P2X4 and decreases ATP-activated P2X4 currents by stabilizing the closed conformation of the channel.
format Online
Article
Text
id pubmed-6572003
institution National Center for Biotechnology Information
language English
publishDate 2019
publisher Rockefeller University Press
record_format MEDLINE/PubMed
spelling pubmed-65720032019-12-04 Bile acids inhibit human purinergic receptor P2X4 in a heterologous expression system Ilyaskin, Alexandr V. Sure, Florian Nesterov, Viatcheslav Haerteis, Silke Korbmacher, Christoph J Gen Physiol Research Articles We recently demonstrated that bile acids, especially tauro-deoxycholic acid (t-DCA), modify the function of the acid-sensing ion channel ASIC1a and other members of the epithelial sodium channel (ENaC)/degenerin (DEG) ion channel family. Surprisingly, ASIC1 shares a high degree of structural similarity with the purinergic receptor P2X4, a nonselective cation channel transiently activated by ATP. P2X4 is abundantly expressed in the apical membrane of bile duct epithelial cells and is therefore exposed to bile acids under physiological conditions. Here, we hypothesize that P2X4 may also be modulated by bile acids and investigate whether t-DCA and other common bile acids affect human P2X4 heterologously expressed in Xenopus laevis oocytes. We find that application of either t-DCA or unconjugated deoxycholic acid (DCA; 250 µM) causes a strong reduction (∼70%) of ATP-activated P2X4-mediated whole-cell currents. The inhibitory effect of 250 µM tauro-chenodeoxycholic acid is less pronounced (∼30%), and 250 µM chenodeoxycholic acid, cholic acid, or tauro-cholic acid did not significantly alter P2X4-mediated currents. t-DCA inhibits P2X4 in a concentration-dependent manner by reducing the efficacy of ATP without significantly changing its affinity. Single-channel patch-clamp recordings provide evidence that t-DCA inhibits P2X4 by stabilizing the channel’s closed state. Using site-directed mutagenesis, we identifiy several amino acid residues within the transmembrane domains of P2X4 that are critically involved in mediating the inhibitory effect of t-DCA on P2X4. Importantly, a W46A mutation converts the inhibitory effect of t-DCA into a stimulatory effect. We conclude that t-DCA directly interacts with P2X4 and decreases ATP-activated P2X4 currents by stabilizing the closed conformation of the channel. Rockefeller University Press 2019-06-03 2019-04-15 /pmc/articles/PMC6572003/ /pubmed/30988062 http://dx.doi.org/10.1085/jgp.201812291 Text en © 2019 Ilyaskin et al. http://www.rupress.org/terms/https://creativecommons.org/licenses/by-nc-sa/4.0/This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms/). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 International license, as described at https://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Research Articles
Ilyaskin, Alexandr V.
Sure, Florian
Nesterov, Viatcheslav
Haerteis, Silke
Korbmacher, Christoph
Bile acids inhibit human purinergic receptor P2X4 in a heterologous expression system
title Bile acids inhibit human purinergic receptor P2X4 in a heterologous expression system
title_full Bile acids inhibit human purinergic receptor P2X4 in a heterologous expression system
title_fullStr Bile acids inhibit human purinergic receptor P2X4 in a heterologous expression system
title_full_unstemmed Bile acids inhibit human purinergic receptor P2X4 in a heterologous expression system
title_short Bile acids inhibit human purinergic receptor P2X4 in a heterologous expression system
title_sort bile acids inhibit human purinergic receptor p2x4 in a heterologous expression system
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6572003/
https://www.ncbi.nlm.nih.gov/pubmed/30988062
http://dx.doi.org/10.1085/jgp.201812291
work_keys_str_mv AT ilyaskinalexandrv bileacidsinhibithumanpurinergicreceptorp2x4inaheterologousexpressionsystem
AT sureflorian bileacidsinhibithumanpurinergicreceptorp2x4inaheterologousexpressionsystem
AT nesterovviatcheslav bileacidsinhibithumanpurinergicreceptorp2x4inaheterologousexpressionsystem
AT haerteissilke bileacidsinhibithumanpurinergicreceptorp2x4inaheterologousexpressionsystem
AT korbmacherchristoph bileacidsinhibithumanpurinergicreceptorp2x4inaheterologousexpressionsystem