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Controlling epithelial sodium channels with light using photoswitchable amilorides

Nature Chemistry volume 6, pages 712–719 (2014)Cite this article

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Abstract

Amiloride is a widely used diuretic that blocks epithelial sodium channels (ENaCs). These heterotrimeric transmembrane proteins, assembled from β, γ and α or δ subunits, effectively control water transport across epithelia and sodium influx into non-epithelial cells. The functional role of δβγENaC in various organs, including the human brain, is still poorly understood and no pharmacological tools are available for the functional differentiation between α- and δ-containing ENaCs. Here we report several photoswitchable versions of amiloride. One compound, termed PA1, enables the optical control of ENaC channels, in particular the δβγ isoform, by switching between blue and green light, or by turning on and off blue light. PA1 was used to modify functionally δβγENaC in amphibian and mammalian cells. We also show that PA1 can be used to differentiate between δβγENaC and αβγENaC in a model for the human lung epithelium.

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Figure 1: ENaCs and their blockers.
Figure 2: PA synthesis and characterization.
Figure 3: PA1 photoswitching in Xenopus oocytes.
Figure 4: Switching δβγENaC in HEK cells using 10 μM PA1.
Figure 5: Photocontrol of transepithelial potential in H441 monolayers.

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Acknowledgements

We thank the European Research Commission for an ERC Advanced Grant (Grant No. 268795 to D.T.). M.A. is supported by grants from the German Research Foundation (AL1453/1-1 and AL1453/1-2), M.F. and W.C. acknowledge a grant provided by the Federal State of Hesse (LOEWE Research Focus, Non-neuronal cholinergic systems). M.S. was supported by a grant from the German Study Foundation and the International Max Planck Research School (IMPRS-LS). We acknowledge the support of K. Hüll (chemical synthesis) and L. de la Osa de la Rosa (cell-culture work), and we thank D. Barber for helpful comments. We also thank D. Alvarez de la Rosa for providing constructs of all ENaC subunits in pcDNA3.1.

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Authors and Affiliations

  1. Department of Chemistry and Center for Integrated Protein Science, Ludwig Maximilians-Universität München, Butenandtstraße 5–13 (F4.086), Munich, 81377, Germany

    Matthias Schönberger & Dirk Trauner

  2. Institute of Animal Physiology, Justus Liebig University Giessen, Heinrich-Buff-Ring 26, Giessen, 35392, Germany

    Mike Althaus, Martin Fronius & Wolfgang Clauss

  3. Department of Physiology, University of Otago, PO Box 913, Dunedin, 9054, New Zealand

    Martin Fronius

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  1. Matthias Schönberger
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Contributions

D.T., M.A., M.S. and M.F. conceived the study and designed the experiments. M.S. performed the chemical synthesis and UV/vis characterization. M.S. and M.A. performed the electrophysiological characterization. D.T. and W.C. supervised the study and wrote the paper, together with M.S., M.F. and M.A.

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Correspondence to Dirk Trauner.

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Schönberger, M., Althaus, M., Fronius, M. et al. Controlling epithelial sodium channels with light using photoswitchable amilorides. Nature Chem 6, 712–719 (2014). https://doi.org/10.1038/nchem.2004

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