title: Optogenetic Vision Restoration Using Rhodopsin for Enhanced Sensitivity.
abstract: Retinal disease is one of the most active areas of gene therapy, with clinical trials ongoing in the United States for five diseases. There are currently no treatments for patients with late-stage disease in which photoreceptors have been lost. Optogenetic gene therapies are in development, but, to date, have suffered from the low light sensitivity of microbial opsins, such as channelrhodopsin and halorhodopsin, and azobenzene-based photoswitches. Several groups have shown that photoreceptive G-protein-coupled receptors (GPCRs) can be expressed heterologously, and photoactivate endogenous Gi/o signaling. We hypothesized such a GPCR could increase sensitivity due to endogenous signal amplification. We targeted vertebrate rhodopsin to retinal ON-bipolar cells of blind rd1 mice and observed restoration of: (i) light responses in retinal explants, (ii) visually-evoked potentials in visual cortex in vivo, and (iii) two forms of visually-guided behavior: innate light avoidance and discrimination of temporal light patterns in the context of fear conditioning. Importantly, both the light responses of the retinal explants and the visually-guided behavior occurred reliably at light levels that were two to three orders of magnitude dimmer than required for channelrhodopsin. Thus, gene therapy with native light-gated GPCRs presents a novel approach to impart light sensitivity for visual restoration in a useful range of illumination.
authors.affiliation: Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California, USA.
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Gaub
authors.affiliation: Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California, USA.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Berry
authors.affiliation: Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California, USA.
authors.forename: Amy E
authors.initials: AE
authors.lastname: Holt
authors.affiliation: Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California, USA.|Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California, USA.|Physical Bioscience Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA.
authors.forename: Ehud Y
authors.initials: EY
authors.lastname: Isacoff
authors.affiliation: Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California, USA.|Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California, USA.|Vision Science, University of California, Berkeley, California, USA.
authors.forename: John G
authors.initials: JG
authors.lastname: Flannery
mesh_terms: D000818:Animals; D000229:Dependovirus / Q000235:genetics; D000066630:Ectopic Gene Expression; D005074:Evoked Potentials, Visual / Q000235:genetics / Q000528:radiation effects; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics; D008027:Light; D051379:Mice; D062308:Optogenetics / Q000379:methods*; D010775:Photic Stimulation; D012160:Retina / Q000166:cytology / Q000378:metabolism; D051245:Retinal Bipolar Cells / Q000378:metabolism; D012165:Retinal Ganglion Cells / Q000378:metabolism; D012243:Rhodopsin / Q000235:genetics*; D014161:Transduction, Genetic; D014785:Vision, Ocular / Q000235:genetics*; D014796:Visual Perception
chemical_list: D012243:Rhodopsin