Photochemical control of endogenous ion channels and cellular excitability

• Published in: Nature methods Vol. 5; no. 4; pp. 331 - 338
• Main Authors: Trauner, Dirk, Kristan, William B, Gaudry, Quentin, Borges, Katharine, Otis, Thomas S, Dunn, Timothy W, Karakossian, Movses H, Kramer, Richard H, Fortin, Doris L, Banghart, Matthew R, Wagenaar, Daniel A
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.04.2008; Nature Publishing Group
• Subjects: Action Potentials - radiation effects; Affinity Labels - chemistry; Animals; Azo Compounds - chemistry; Bioinformatics; Biological Microscopy; Biological Techniques; Biomedical and Life Sciences; Biomedical Engineering/Biotechnology; Calcium; Cells; Cells, Cultured; Cerebellum - cytology; Cerebellum - metabolism; Cerebellum - radiation effects; Gene expression; Genes; Hippocampus - cytology; Hippocampus - metabolism; Hippocampus - radiation effects; Hirudinea; Ion Channel Gating - radiation effects; Ion channels; Ions; Isomerization; Leeches; Life Sciences; Methods; Neurons - metabolism; Neurons - radiation effects; Optical properties; Photic Stimulation; Photochemicals; Photochemistry; Physiological aspects; Potassium Channels - metabolism; Proteomics; Quaternary Ammonium Compounds - chemistry; Rats; Wavelengths; United States
• ISSN: 1548-7091; 1548-7105
• DOI: 10.1038/nmeth.1187

Light-activated ion channels provide a precise and noninvasive optical means for controlling action potential firing, but the genes encoding these channels must first be delivered and expressed in target cells. Here we describe a method for bestowing light sensitivity onto endogenous ion channels that does not rely on exogenous gene expression. The method uses a synthetic photoisomerizable small molecule, or photoswitchable affinity label (PAL), that specifically targets K + channels. PALs contain a reactive electrophile, enabling covalent attachment of the photoswitch to naturally occurring nucleophiles in K + channels. Ion flow through PAL-modified channels is turned on or off by photoisomerizing PAL with different wavelengths of light. We showed that PAL treatment confers light sensitivity onto endogenous K + channels in isolated rat neurons and in intact neural structures from rat and leech, allowing rapid optical regulation of excitability without genetic modification.