Zinc pyrithione-mediated activation of voltage-gated KCNQ potassium channels rescues epileptogenic mutants

Abstract

KCNQ potassium channels are activated by changes in transmembrane voltage and play an important role in controlling electrical excitability. Human mutations of KCNQ2 and KCNQ3 potassium channel genes result in reduction or loss of channel activity and cause benign familial neonatal convulsions (BFNCs). Thus, small molecules capable of augmenting KCNQ currents are essential both for understanding the mechanism of channel activity and for developing therapeutics. We performed a high-throughput screen in search for agonistic compounds potentiating KCNQ potassium channels. Here we report identification of a new opener, zinc pyrithione (1), which activates both recombinant and native KCNQ M currents. Interactions with the channel protein cause an increase of single-channel open probability that could fully account for the overall conductance increase. Separate point mutations have been identified that either shift the concentration dependence or affect potentiation efficacy, thereby providing evidence for residues influencing ligand binding and downstream events. Furthermore, zinc pyrithione is capable of rescuing the mutant channels causal to BFNCs.

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Figure 1: ZnPy potentiated potassium currents induced by KCNQ homomultimers.
Figure 2: Combinatorial effects on KCNQ2 current by potassium channel blockers and ZnPy.
Figure 3: Biophysical effects of ZnPy on KCNQ channels.
Figure 4: ZnPy increases the Po of KCNQ2 channel.
Figure 5: Molecular determinants for ZnPy sensitivity.
Figure 6: ZnPy potentiation of native M current.
Figure 7: ZnPy effects on BFNC mutant channels expressed in CHO cells.

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Acknowledgements

We thank T. Jentsch (Zentrum für Molekulare Neurobiologie, Hamburg), D. Makinnon (State University of New York, Stony Brook), M. Sanguinetti (University of Utah), M. Shapiro (University of Texas Health Science Center, San Antonio) and V. Vardanyan (Universität Hamburg) for gifts of cDNAs. We thank M. Fratine, A. Ince, S. Long, M. Spieker and K. Xie for technical assistance. We also thank B. Coblitz for help with structural modeling and our colleagues and members of the Li laboratory for valuable discussions and comments on the manuscript. The N-type calcium channel stable line was a kind gift from D. Lipscombe and D. Yue. This work is supported by a grant from the US National Institutes of Health to M.L. (GM70959).

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Authors

Contributions

Q.X. performed all electrophysiological recordings and analyses. H.S. performed high-throughput compound screens and constructed site-directed mutants. Q.X. and H.S. constructed vectors and established cell lines expressing KCNQ channels. M.L. helped conceive experiments.

Note: Supplementary information and chemical compound information is available on the Nature Chemical Biology website.

Corresponding author

Correspondence to Min Li.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Fig. 1

Zinc pyrithione effects on other potassium channels and N-type calcium channel. (PDF 15 kb)

Supplementary Fig. 2

Complexed form of ZnPy is required for potentiation. (PDF 30 kb)

Supplementary Fig. 3

Other divalent ion effects on KCNQ2 current. (PDF 26 kb)

Supplementary Fig. 4

Synthesis of zinc pyrithione and sodium pyrithione. (PDF 15 kb)

Supplementary Fig. 5

Stoichiometric preference of Zn ion and pyrithione. (PDF 17 kb)

Supplementary Fig. 6

ZnPy effects on KCNQ2 and KCNQ2/3 deactivation. (PDF 102 kb)

Supplementary Fig. 7

Differential modulatory sites on KCNQ channel and retigabine. (PDF 31 kb)

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Xiong, Q., Sun, H. & Li, M. Zinc pyrithione-mediated activation of voltage-gated KCNQ potassium channels rescues epileptogenic mutants. Nat Chem Biol 3, 287–296 (2007). https://doi.org/10.1038/nchembio874

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