PT  - JOURNAL ARTICLE
AU  - Jonathan S. Marvin
AU  - Yoshiteru Shimoda
AU  - Vincent Malgoire
AU  - Marco Leite
AU  - Takashi Kawashima
AU  - Thomas P. Jensen
AU  - Erika L. Knott
AU  - Ondrej Novak
AU  - Kaspar Podgorski
AU  - Nancy J. Leidenheimer
AU  - Dmitri A. Rusakov
AU  - Misha B. Ahrens
AU  - Dimitri M. Kullmann
AU  - Loren L. Looger
TI  - A genetically encoded fluorescent sensor for <em>in vivo</em> imaging of GABA
AID  - 10.1101/322578
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 322578
4099  - http://biorxiv.org/content/early/2018/05/14/322578.short
4100  - http://biorxiv.org/content/early/2018/05/14/322578.full
AB  - Current techniques for monitoring GABA, the primary inhibitory neurotransmitter in vertebrates, cannot follow ephemeral transients in intact neural circuits. We applied the design principles used to create iGluSnFR, a fluorescent reporter of synaptic glutamate, to develop a GABA sensor using a protein derived from a previously unsequenced Pseudomonas fluorescens strain. Structure-guided mutagenesis and library screening led to a usable iGABASnFR (ΔF/Fmax ~ 2.5, Kd ~ 9 μM, good specificity, adequate kinetics). iGABASnFR is genetically encoded, detects single action potential-evoked GABA release events in culture, and produces readily detectable fluorescence increases in vivo in mice and zebrafish. iGABASnFR enabled tracking of: (1) mitochondrial GABA content and its modulation by an anticonvulsant; (2) swimming-evoked GABAergic transmission in zebrafish cerebellum; (3) GABA release events during inter-ictal spikes and seizures in awake mice; and (4) GABAergic tone decreases during isoflurane anesthesia. iGABASnFR will permit high spatiotemporal resolution of GABA signaling in intact preparations.