Non-invasive optical control of endogenous $Ca^{2+}$ channels in awake mice

Abstract

Modulating proteins activities via light-activated photoreceptors offered unexpected advance in the field ofscience. Especially universal downstream signaling molecule, $Ca^{2+}$, may provide insights on the dynamic natureof cellular behaviors and result in the comprehension of higher order outcomes due to extensive usages tointerconnect disparate cellular networks. Previously we designed $Ca^{2+}$-selective optogenetic tool by activatingendogenous CRAC channel has been applied to manipulate $Ca^{2+}$ activities in many cellular systems and even invivo system. Blue-light driven oligomerization of cryptochrome2 (CRY2) enable to form active STIM1conformation and subsequently promote activation of endogenous CRAC channels, in turn, elevating $[$Ca^{2+}$]_i$.However, the low penetration property of blue light-responsive photoreceptors is considered inadequate to use invivo without inserting optic fiber insertion. Here, we present an ultra-light sensitive optogenetic $Ca^{2+}$ modulator,named “monSTIM1” developed by engineering cryptochrome2 to control $Ca^{2+}$ signaling in the brain of awakemice through non-invasive light delivery. Through expressing monSTIM1 in mice brain, we are able to induce $Ca^{2+}$-dependent immediate early gene, c-Fos expression without any alteration of intact mice brain. Furthermore, $Ca^{2+}$ relative behavior of mice can be affected through non-invasive activation of monSTIM1 demonstrating itsability to control $Ca^{2+}$ signaling in the brain of awake mice through non-invasive light delivery.