Using a bistable animal opsin for switchable and scalable optogenetic inhibition of neurons

Abstract

There is no consensus on the best optogenetic tool for neuronal inhibition. Lamprey parapinopsin ('Lamplight') is a Gi/o-coupled bistable animal opsin that can be activated and deactivated by short and long wavelength light, respectively. Since native mechanisms of neuronal inhibition frequently employ Gi/o signalling, we asked here whether Lamplight could be used for optogenetic silencing. We show that short (405nm) and long (525nm) wavelength pulses repeatedly switch Lamplight between stable signalling active and inactive states, and that combining these wavelengths can be used to achieve intermediate levels of activity. We demonstrate that these properties can be applied to produce switchable and scalable neuronal hyperpolarisation, and suppression of spontaneous spike firing in the mouse hypothalamic suprachiasmatic nucleus. We show that expressing Lamplight in (predominantly) ON bipolar cells can photosensitise retinas following advanced photoreceptor degeneration, and that 405 and 525nm stimuli can produce responses of opposite sign in output neurons of the retina. Lamplight-driven responses to both activating (405nm) and deactivating (525nm) light can occur within 500ms and be elicited by intensities at least 10x below threshold for available inhibitory optogenetic tools. We conclude that Lamplight can co-opt endogenous signalling mechanisms to allow optogenetic inhibition that is scalable, sustained and rapidly reversible.

Bipolar cell targeted optogenetic gene therapy restores parallel retinal signaling and high-level vision in the degenerated retina

“…Screening of opsin constructs in HEK293-GIRK cells. GPCR opsins previously used in OBC-targeted gene therapies include the Opto-mGluR6 chimera 6 , rhodopsin 3 , medium-wave cone opsin (OPN1MW) 5,8 and lamprey parapinopsin 17 . Our aim was to examine the maximum potential of this therapeutic approach.…”

High-performance GPCR optogenetics based on molecular properties of animal opsins, MosOpn3 and LamPP

“…In manipulating GPCR signaling, chemical manipulation, namely chemogenetics using chemoreceptors such as DREADD (designer receptor exclusively activated by designer drugs) have been widely used [62][63][64] , which is in contrast to the situation of optogenetics with animal opsins, mainly bleaching opsins. The low popularity of optical manipulation of GPCR signaling was mainly due to the absence of effective and robust tools but the situation has been recently changing with bistable opsins, especially MosOpn3 and LamPP 28,[36][37][38] , and advantages of them and their derivatives were systematically demonstrated based on their molecular properties in this paper. The main advantage of chemogenetics is that stimuli (chemicals) can be reliably delivered deep inside the body.…”

“…The same is true for the signal transduction level. The G protein activation by parapinopsin were up-and down-regulated by UV and green light illumination, respectively in vitro and in vivo [33][34][35][36][37][38] , demonstrating its optogenetic potential for color-dependent on and off of GPCR signaling.…”

Bipolar Cell Targeted Optogenetic Gene Therapy Restores Parallel Retinal Signaling And High-Level Vision In The Degenerated Retina

“…GPCR opsins previously used in OBC-targeted gene therapies include the Opto-mGluR6 chimera 5 , rhodopsin 2 , medium-wave cone opsin (OPN1MW) 4,7 and lamprey parapinopsin 14 . Our aim was to examine the maximum potential of this therapeutic approach.…”