Optimization of a GCaMP Calcium Indicator for Neural Activity Imaging

• DOI: 10.1523/jneurosci.2601-12.2012
• Publication Date: 2012-10-03T20:44:02Z
• Authors: Jasper Akerboom; Tsai-Wen Chen; Trevor J. Wardill; Lin Tian; Jonathan S. Marvin; Sevinç Mutlu; Nicole Carreras C...; Federico Esposti; Bart G. Borghuis; Xiaonan Richard Sun; Andrew Gordus; Michael B. Orger; Ruben Portugues; Florian Engert; John J. Macklin; Alessandro Filosa; Aman Aggarwal; Rex A. Kerr; Ryousuke Takagi; Sebastian Kracun; Eiji Shigetomi; Baljit S. Khakh; Herwig Baier; Leon Lagnado; Samuel S.-H. Wang; Cornelia I. Bargmann; Bruce E. Kimmel; Vivek Jayaraman; Karel Svoboda; Douglas S. Kim; Eric R. Schreiter; Loren L. Looger
• Keywords: Models, Molecular; 570; 0303 health sciences; Lasers; Genetic Vectors; Green Fluorescent Proteins; Crystallography, X-Ray; Hippocampus; Mice; 03 medical and health sciences; Drosophila melanogaster; HEK293 Cells; Astrocytes; Larva; Genes, Synthetic; Mutagenesis, Site-Directed; Animals; Humans; Female; Fluorometry; Calcium Signaling; Caenorhabditis elegans; Fluorescent Dyes

Genetically encoded calcium indicators (GECIs) are powerful tools for systems neuroscience. Recent efforts in protein engineering have significantly increased the performance of GECIs. The state-of-the art single-wavelength GECI, GCaMP3, has been deployed in a number of model organisms and can reliably detect three or more action potentials in short bursts in several systemsin vivo. Through protein structure determination, targeted mutagenesis, high-throughput screening, and a battery ofin vitroassays, we have increased the dynamic range of GCaMP3 by severalfold, creating a family of “GCaMP5” sensors. We tested GCaMP5s in several systems: cultured neurons and astrocytes, mouse retina, andin vivoinCaenorhabditischemosensory neurons,Drosophilalarval neuromuscular junction and adult antennal lobe, zebrafish retina and tectum, and mouse visual cortex. Signal-to-noise ratio was improved by at least 2- to 3-fold. In the visual cortex, two GCaMP5 variants detected twice as many visual stimulus-responsive cells as GCaMP3. By combiningin vivoimaging with electrophysiology we show that GCaMP5 fluorescence provides a more reliable measure of neuronal activity than its predecessor GCaMP3. GCaMP5 allows more sensitive detection of neural activityin vivoand may find widespread applications for cellular imaging in general.