Optogenetic control of mitochondrial metabolism & Ca2+ signaling by mitochondria-Targeted opsins

Key mitochondrial functions such as ATP production, Ca2+ uptake
and release, and substrate accumulation depend on the proton
electrochemical gradient (??H+) across the inner membrane. Although
several drugs can modulate ??H+, their effects are hardly
reversible, and lack cellular specificity and spatial resolution. Although
channelrhodopsins are widely used to modulate the
plasma membrane potential of excitable cells, mitochondria have
thus far eluded optogenetic control. Here we describe a toolkit of
optometabolic constructs based on selective targeting of channelrhodopsins
with distinct functional properties to the inner mitochondrial
membrane of intact cells. We show that our strategy
enables a light-dependent control of the mitochondrial membrane
potential (??m) and coupled mitochondrial functions such as ATP
synthesis by oxidative phosphorylation, Ca2+ dynamics, and respiratory
metabolism. By directly modulating ??m, the mitochondriatargeted
opsins were used to control complex physiological processes
such as spontaneous beats in cardiac myocytes and glucose-dependent
ATP increase in pancreatic ?-cells. Furthermore, our optometabolic
tools allow modulation of mitochondrial functions in single cells
and defined cell regions.