Abstract
Mutations in members of the KCNQ channel family underlie multiple diseases affecting the nervous and cardiovascular systems. Despite their clinical relevance, research into these channels is limited by the lack of subtype-selective inhibitors, making it difficult to differentiate the physiological function of each family member in vivo. We have proposed that KCNQ channels might partially underlie the calcium-activated slow afterhyperpolarization (sAHP), a neuronal conductance whose molecular components are uncertain. Here, we investigated whether 3-(triphenylmethylaminomethyl)pyridine (UCL2077), identified previously as an inhibitor of the sAHP in neurons, acts on members of the KCNQ family expressed in heterologous cells. We found that 3 μM UCL2077 strongly inhibits KCNQ1 and KCNQ2 channels and weakly blocks KCNQ4 channels in a voltage-independent manner. In contrast, UCL2077 potentiates KCNQ5 channels at more positive membrane potentials, with little effect at negative membrane potentials. We found that the effect of UCL2077 on KCNQ3 is bimodal: currents are enhanced at negative membrane potentials and inhibited at positive potentials. We found that UCL2077 facilitates KCNQ3 currents by inducing a leftward shift in the KCNQ3 voltage-dependence, a shift dependent on tryptophan 265. Finally, we show that UCL2077 has intermediate effects on KCNQ2/3 heteromeric channels compared with KCNQ2 and KCNQ3 homomers. Together, our data demonstrate that UCL2077 acts on KCNQ channels in a subtype-selective manner. This feature should make UCL2077 a useful tool for distinguishing KCNQ1 and KCNQ2 from less-sensitive KCNQ family members in neurons and cardiac cells in future studies.
Footnotes
↵
The online version of this article (available at http://molpharm.aspetjournals.org) contains supplemental material.
This research was supported by the National Institutes of Health National Institute of Neurological Disorders and Stroke [Grant NS060890].
Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.
doi:10.1124/mol.110.066100.
-
ABBREVIATIONS:
- sAHP
- slow afterhyperpolization
- EGFP
- enhanced green fluorescence protein
- HEK
- human embryonic kidney
- UCL2077
- 3-(triphenylmethylaminomethyl)pyridine
- XE-991
- 10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone
- G-V
- conductance-to-voltage.
- Received May 5, 2010.
- Accepted September 14, 2010.
- Copyright © 2010 The American Society for Pharmacology and Experimental Therapeutics
MolPharm articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|