A New Promoter Allows Optogenetic Vision Restoration with Enhanced Sensitivity in Macaque Retina

Mol Ther. 2017 Nov 1;25(11):2546-2560. doi: 10.1016/j.ymthe.2017.07.011. Epub 2017 Jul 20.


The majority of inherited retinal degenerations converge on the phenotype of photoreceptor cell death. Second- and third-order neurons are spared in these diseases, making it possible to restore retinal light responses using optogenetics. Viral expression of channelrhodopsin in the third-order neurons under ubiquitous promoters was previously shown to restore visual function, albeit at light intensities above illumination safety thresholds. Here, we report (to our knowledge, for the first time) activation of macaque retinas, up to 6 months post-injection, using channelrhodopsin-Ca2+-permeable channelrhodopsin (CatCh) at safe light intensities. High-level CatCh expression was achieved due to a new promoter based on the regulatory region of the gamma-synuclein gene (SNCG) allowing strong expression in ganglion cells across species. Our promoter, in combination with clinically proven adeno-associated virus 2 (AAV2), provides CatCh expression in peri-foveolar ganglion cells responding robustly to light under the illumination safety thresholds for the human eye. On the contrary, the threshold of activation and the proportion of unresponsive cells were much higher when a ubiquitous promoter (cytomegalovirus [CMV]) was used to express CatCh. The results of our study suggest that the inclusion of optimized promoters is key in the path to clinical translation of optogenetics.

Keywords: AAV; optogenetics; retinal gene therapy; retinitis pigmentosa; visual restoration.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Channelrhodopsins / genetics*
  • Channelrhodopsins / metabolism
  • Dependovirus / genetics
  • Dependovirus / metabolism
  • Disease Models, Animal
  • Gene Expression
  • Genetic Therapy / methods
  • Genetic Vectors / administration & dosage*
  • Genetic Vectors / chemistry
  • Genetic Vectors / metabolism
  • Intravitreal Injections
  • Light
  • Macaca fascicularis
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Optogenetics
  • Photoreceptor Cells, Vertebrate / metabolism
  • Photoreceptor Cells, Vertebrate / pathology
  • Promoter Regions, Genetic*
  • Recovery of Function*
  • Retinal Degeneration / genetics
  • Retinal Degeneration / metabolism
  • Retinal Degeneration / pathology
  • Retinal Degeneration / therapy*
  • Retinal Ganglion Cells / metabolism
  • Retinal Ganglion Cells / pathology
  • Transduction, Genetic
  • Transgenes
  • Vision, Ocular / physiology


  • Channelrhodopsins