Photochemical control of endogenous ion channels and cellular excitability.
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.
Fortin
Doris L
DL
Department of Molecular and Cell Biology, University of California Berkeley, 121 Life Sciences Addition, Berkeley, California 94720, USA.
Banghart
Matthew R
MR
Dunn
Timothy W
TW
Borges
Katharine
K
Wagenaar
Daniel A
DA
Gaudry
Quentin
Q
Karakossian
Movses H
MH
Otis
Thomas S
TS
Kristan
William B
WB
Trauner
Dirk
D
Kramer
Richard H
RH
D000200:Action Potentials / Q000528:radiation effects*; D000345:Affinity Labels / Q000737:chemistry; D000818:Animals; D001391:Azo Compounds / Q000737:chemistry; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects; D015640:Ion Channel Gating / Q000528:radiation effects*; D007865:Leeches; D009474:Neurons / Q000378:metabolism / Q000528:radiation effects; D010775:Photic Stimulation; D010777:Photochemistry; D015221:Potassium Channels / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D051381:Rats
D000345:Affinity Labels; D001391:Azo Compounds; D015221:Potassium Channels; D000644:Quaternary Ammonium Compounds; C009850:azobenzene