Biophysical Society Thematic Meeting | Bucharest 2026

Biophysics of Membrane Reactions in Brian

Poster Abstracts

6-POS Board 6 ESTABLISHMENT OF FUNCTIONAL ASSAY SYSTEMS FOR RHODOPSIN-BASED OPTOGENETIC VISION RESTORATION Moe Kikuchi 1 ; Shoko Hososhima 1 ; Mitsumasa Koyanagi 2 ; Akihisa Terakita 2 ; Hideki Kandori 1 ; Satoshi Tsunoda 1 ; 1 Nagoya Institute of Technology, Department of Life Science and Applied Chemistry, Nagoya, Japan 2 Osaka Metropolitan University, Department of Biology, Graduate School of Science, Osaka, Japan Retinitis pigmentosa is an inherited retinal degenerative disease characterized by progressive photoreceptor loss, ultimately leading to blindness. Although more than 60 causative genes and over 3,000 of pathogenic mutations have been identified, gene-specific therapies remain challenging due to genetic heterogeneity. Optogenetic vision restoration has emerged as a promising gene-independent therapy, in which light-sensitive opsins are ectopically expressed in surviving retinal neurons such as bipolar or ganglion cells to restore photosensitivity. To advance this approach, we aim to establish quantitative and reproducible assay systems for evaluating rhodopsin function from a biophysical perspective, with direct relevance to optogenetic vision restoration. In this study, we focused on a non-visual opsin that exhibits molecular properties distinct from conventional opsins. To test its signaling function as an optogenetic tool, this opsin was heterologously expressed together with an inwardly rectifying potassium channel, GIRK, in mammalian ND7/23 cells. Light-induced GIRK channel activity was monitored using whole-cell patch-clamp electrophysiology as a direct electrical readout of G protein activation. While cells expressing GIRK1 or GIRK2 alone showed no light-responsive currents, robust GIRK currents were reproducibly observed upon light stimulation in cells co-expressing the non-visual opsin, GIRK1, and GIRK2, demonstrating effective coupling of the opsin to endogenous G protein signaling pathways. Furthermore, repeated light stimulation revealed that the non-visual opsin could support reproducible GIRK activation, an essential property for potential visual signal transmission. Together, these results establish a versatile electrophysiological assay framework for characterizing opsin-mediated G protein signaling, providing a biophysical foundation for the development and optimization of animal opsin-based optogenetic strategies for vision restoration.

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