TY - JOUR
T1 - Lubiprostone activates CFTR, but not ClC-2, via the prostaglandin receptor (EP4)
AU - Norimatsu, Yohei
AU - Moran, Aurelia R.
AU - MacDonald, Kelvin D.
N1 - Funding Information:
The authors gratefully acknowledge David C. Dawson and William R. Skach for their mentorship. Supported by Parker B. Frances Pulmonary Fellowship (KDM), OHSU Child Health Research Center ( K12 HD057588 ), National Institute for Diabetes, Digestive and Kidney Diseases ( DK45880 ), and the Cystic Fibrosis Foundation ( DAWSON08G0 ).
PY - 2012/9/28
Y1 - 2012/9/28
N2 - The goal of this study was to determine the mechanism of lubiprostone activation of epithelial chloride transport. Lubiprostone is a bicyclic fatty acid approved for the treatment of constipation [1]. There is uncertainty, however, as to how lubiprostone increases epithelial chloride transport. Direct stimulation of ClC-2 and CFTR chloride channels as well as stimulation of these channels via the EP4 receptor has been described [2-5]. To better define this mechanism, two-electrode voltage clamp was used to assay Xenopus oocytes expressing ClC-2, with or without co-expression of the EP4 receptor or β adrenergic receptor (βAR), for changes in conductance elicited by lubiprostone. Oocytes co-expressing CFTR and either βAR or the EP4 receptor were also studied. In oocytes co-expressing ClC-2 and βAR conductance was stimulated by hyperpolarization and acidic pH (pH=6), but there was no response to the β adrenergic agonist, isoproterenol. Oocytes expressing ClC-2 only or co-expressing ClC-2 and EP4 did not respond to the presence of 0.1, 1, or 10μM lubiprostone in the superperfusate. Oocytes co-expressing CFTR and βAR did not respond to hyperpolarization, acidic pH, or 1μM lubiprostone. However, conductance was elevated by isoproterenol and inhibited by CFTRinh172. Co-expression of CFTR and EP4 resulted in lubiprostone-stimulated conductance, which was also sensitive to CFTRinh172. The EC50 for lubiprostone mediated CFTR activation was ∼10nM. These results demonstrate no direct action of lubiprostone on either ClC-2 or CFTR channels expressed in oocytes. However, the results confirm that CFTR can be activated by lubiprostone via the EP4 receptor in oocytes.
AB - The goal of this study was to determine the mechanism of lubiprostone activation of epithelial chloride transport. Lubiprostone is a bicyclic fatty acid approved for the treatment of constipation [1]. There is uncertainty, however, as to how lubiprostone increases epithelial chloride transport. Direct stimulation of ClC-2 and CFTR chloride channels as well as stimulation of these channels via the EP4 receptor has been described [2-5]. To better define this mechanism, two-electrode voltage clamp was used to assay Xenopus oocytes expressing ClC-2, with or without co-expression of the EP4 receptor or β adrenergic receptor (βAR), for changes in conductance elicited by lubiprostone. Oocytes co-expressing CFTR and either βAR or the EP4 receptor were also studied. In oocytes co-expressing ClC-2 and βAR conductance was stimulated by hyperpolarization and acidic pH (pH=6), but there was no response to the β adrenergic agonist, isoproterenol. Oocytes expressing ClC-2 only or co-expressing ClC-2 and EP4 did not respond to the presence of 0.1, 1, or 10μM lubiprostone in the superperfusate. Oocytes co-expressing CFTR and βAR did not respond to hyperpolarization, acidic pH, or 1μM lubiprostone. However, conductance was elevated by isoproterenol and inhibited by CFTRinh172. Co-expression of CFTR and EP4 resulted in lubiprostone-stimulated conductance, which was also sensitive to CFTRinh172. The EC50 for lubiprostone mediated CFTR activation was ∼10nM. These results demonstrate no direct action of lubiprostone on either ClC-2 or CFTR channels expressed in oocytes. However, the results confirm that CFTR can be activated by lubiprostone via the EP4 receptor in oocytes.
KW - CFTR
KW - Chloride channel
KW - ClC-2
KW - Lubiprostone
KW - Prostaglandin
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U2 - 10.1016/j.bbrc.2012.08.097
DO - 10.1016/j.bbrc.2012.08.097
M3 - Article
C2 - 22960173
AN - SCOPUS:84866905969
SN - 0006-291X
VL - 426
SP - 374
EP - 379
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 3
ER -