Optogenetic restoration of high-sensitivity vision using ChRmine- and ChroME-based channelrhodopsins

Victoria C Fong; Beatrice M Le; Antonia Stefanov; Vivian Lee; Seohyun Park; Adithya Sivakumar; Sabrina Spatny; Meike Visel; W Rowland Taylor; Stephen G Brohawn; John G Flannery

doi:10.1038/s41598-025-04286-9

Optogenetic restoration of high-sensitivity vision using ChRmine- and ChroME-based channelrhodopsins

Sci Rep. 2025 Jul 1;15(1):21204. doi: 10.1038/s41598-025-04286-9.

Authors

Victoria C Fong^#¹, Beatrice M Le^#¹, Antonia Stefanov², Vivian Lee^{3

4}, Seohyun Park⁵, Adithya Sivakumar⁶, Sabrina Spatny^{4

6}, Meike Visel², W Rowland Taylor^{1

2}, Stephen G Brohawn^{2

6

7}, John G Flannery^{8

9

10}

Affiliations

¹ Herbert Wertheim School of Optometry and Vision Science, The University of California, Berkeley, CA, USA.
² Helen Wills Neuroscience Institute, The University of California, Berkeley, CA, USA.
³ Department of Molecular Environmental Biology, The University of California, Berkeley, CA, USA.
⁴ School of Public Health, The University of California, Berkeley, CA, USA.
⁵ Department of Bioengineering, The University of California, Berkeley, CA, USA.
⁶ Department of Molecular and Cell Biology, The University of California, Berkeley, CA, USA.
⁷ Department of Neuroscience, The University of California, Berkeley, CA, USA.
⁸ Herbert Wertheim School of Optometry and Vision Science, The University of California, Berkeley, CA, USA. flannery@berkeley.edu.
⁹ Helen Wills Neuroscience Institute, The University of California, Berkeley, CA, USA. flannery@berkeley.edu.
¹⁰ Department of Molecular and Cell Biology, The University of California, Berkeley, CA, USA. flannery@berkeley.edu.

^# Contributed equally.

Abstract

Optogenetic gene therapy is a promising mutation-independent treatment that aims to restore visual perception in patients blinded by retinal diseases that cause photoreceptor degeneration. Still, low sensitivity or slow kinetics of currently utilized optogenetic proteins limit the efficacy of such approaches. Here, we evaluated the therapeutic potential of three channelrhodopsin variants: ChRmine, from the algae Rhodomonas lens, ChRmine-T119A, a faster-closing ChRmine variant, and ChroME2s, a second-generation Chronos-based opsin.We expressed these opsins in retinal ganglion cells of rd1 mice, a model of severe retinal degeneration. Single cell electrophysiology demonstrates opsin's large sensitivity to a range of light intensities as well as opsin-expressing retinal ganglion cells generated action potentials in response to light stimulation. Behavioral tests showed ChRmine-T119A's efficacy at 360 lux compared to unmodified ChRmine and ChroME2s. ChRmine and ChroME2s did restore light perception at higher light intensities. Additionally, our dose-response study with ChRmine-T119A revealed that lower viral titers were more effective at restoring light sensitivity. Our study demonstrates that these ChRmine- and ChroME-based opsins can enhance vision in late-stage blinding diseases.

Keywords: Channelrhodopsin; Electrophysiology; Gene therapy; Mouse behavior; Optogenetics; Retinal disease; Vision restoration.

MeSH terms

Animals
Channelrhodopsins* / genetics
Channelrhodopsins* / metabolism
Disease Models, Animal
Genetic Therapy / methods
Light
Mice
Optogenetics* / methods
Retinal Degeneration* / genetics
Retinal Degeneration* / therapy
Retinal Ganglion Cells / metabolism
Vision, Ocular*

Substances

Channelrhodopsins