Table 2.
Characteristics of key opsins used in optogenetic therapeutic studies.
| Opsin | Origin | Type | Peak activation wavelength | Reference | Key preclinical or clinical studies |
|---|---|---|---|---|---|
| Channelrhodopsin 2 (ChR2) | Green alga Chlamydomonas reinhardtii | Microbial light-gated cation channel (depolarising) | 460 nm | Nagel et al. (2003) | rd1 mice (Bi et al., 2006; Zhang et al., 2009; Gaub et al., 2015; Macé et al., 2015) |
|
rd1, rd10, and rd16 mice (Doroudchi et al., 2011) Royal College of Surgeons (RCS) rats (Tomita et al., 2010) | |||||
| NCT02556736 | |||||
| Calcium translocating channelrhodopsin (ChR–CatCh) | L132C mutant of ChR2 with enhanced Ca2+ permeability | 474 nm | Kleinlogel et al. (2011) | Human retinal organoid (Garita-Hernandez et al., 2018) | |
| rd1 mice (Cronin et al., 2014) | |||||
| Non-human primate (Chaffiol et al., 2017) | |||||
| Red-light activated depolarising channelrhodopsin (ReaChR) | Engineered red-shifted ChR variant from Green alga Volvox carteri | 590 nm | Lin et al. (2013) | Human retinal organoid (Garita-Hernandez et al., 2018) | |
| rd1 mice (Sengupta et al., 2016) | |||||
| ChrimsonR | Green alga Chlamydomonas noctigama | 600 nm | Klapoetke et al. (2014) | Human retinal organoid (Garita-Hernandez et al., 2018) | |
| Non-human primates (McGregor et al., 2020; Gauvain et al., 2021) | |||||
| NCT03326336 (ref Sahel et al., 2021) | |||||
| Chronos | Green alga Stigeoclonium helveticum | 500 nm | NCT04278131 | ||
| Enhanced halorhodopsins (eNpHR, eNpHR 2.0 and 3.0) | Engineered variants from archaebacterium Natronomonas pharaonis | Microbial light-gated chloride pump (hyperpolarising) | 590 nm | Gradinaru et al. (2008) | Human retinal organoid (Garita-Hernandez et al., 2018) |
| Gradinaru et al. (2010) | rd1 mice (Busskamp et al., 2010) | ||||
| Cpfl1/Rho−/− mice (Garita-Hernandez et al., 2019) | |||||
| Jaws | Engineered crux-halorhodopsin from Halobacterium salinarum (strain Shark) | 600 nm | Chuong et al. (2014) | Human retinal organoid (Garita-Hernandez et al., 2018) | |
| rd1 mice Chuong et al. (2014) | |||||
| Cpfl1/Rho-/- and rd1 mice (Garita-Hernandez et al., 2019) | |||||
| Non-human primates (Khabou et al., 2018) | |||||
| Rhodopsin (RHO) | Human | Vertebrate G-protein-coupled receptor | 496 nm | – | rd1 mice (Cehajic-Kapetanovic et al., 2015; Eleftheriou et al., 2017; Gaub et al., 2015; McClements et al., 2021) |
| Melanopsin (OPN4) | Human | 480 nm | – | rd1 mice (Lin et al., 2008; Liu et al., 2016; de Silva et al., 2017) | |
| Medium wavelength cone opsin (MWC) | Human | 531 nm | – | rd1 mice (Berry et al., 2019; McClements et al., 2021) | |
| Multicharacteristic opsin (MCO) | (Proprietary) | (Proprietary) | 500 nm; ambient white light used | Wright et al. (2017) | rd10 mice (Wright et al., 2017; Batabyal et al., 2021) |
| NCT04919473 | |||||
| NCT04945772 | |||||
| NCT05417126 |