Gq-coupled receptors regulate numerous physiological processes by activating enzymes and inducing intracellular Ca2+ signals. There is a strong need for an optogenetic tool that enables powerful experimental control over Gq signaling. Here, we present chicken opsin 5 (cOpn5) as the long sought-after, single-component optogenetic tool that mediates ultra-sensitive optical control of intracellular Gq signaling with high temporal and spatial resolution. Expressing cOpn5 in HEK 293T cells and primary mouse astrocytes enables blue light-triggered, Gq-dependent Ca2+ release from intracellular stores and protein kinase C activation. Strong Ca2+ transients were evoked by brief light pulses of merely 10 ms duration and at 3 orders lower light intensity of that for common optogenetic tools. Photostimulation of cOpn5-expressing cells at the subcellular and single-cell levels generated fast intracellular Ca2+ transition, thus demonstrating the high spatial precision of cOpn5 optogenetics. The cOpn5-mediated optogenetics could also be applied to activate neurons and control animal behavior in a circuit-dependent manner. cOpn5 optogenetics may find broad applications in studying the mechanisms and functional relevance of Gq signaling in both non-excitable cells and excitable cells in all major organ systems.
Keywords: Ca2+ imaging; IP3; astrocytes; chicken opsin 5; neural circuit; photostimulation; protein kinase C.
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