Mutation-independent rescue of a novel mouse model of Retinitis Pigmentosa

Gene Ther. 2013 Apr;20(4):425-34. doi: 10.1038/gt.2012.53. Epub 2012 Jul 19.

Abstract

Retinitis Pigmentosa (RP) is the leading cause of inherited blindness in the developed world, affecting approximately 1 in 3000 individuals. Although there is currently no cure for RP, the genetic pathology has been well established. In this study, we developed a novel mouse model of RP (huRhoP347S) expressing a pathogenic human rhodopsin gene with a Pro347Ser (P347S) mutation on a rhodopsin knockout background. These mice undergo severe retinal degeneration at 1 month of age. In contrast to prior studies, this model was administered a gene therapy treatment at 19 days postnata. We evaluated several self-complementary adeno-associated virus (AAV) serotypes for photoreceptor tropism, including scAAV2/2, scAAV2/5, scAAV2/6.2 and scAAV2/9, and found that scAAV2/9 transduced photoreceptors with greater efficiency and expression than other vectors. We engineered an scAAV2/9 vector to contain a microRNA sequence specifically targeting the human rhodopsin gene and demonstrated its ability to silence rhodopsin by 60.2±8.2% in vitro. In addition, we constructed an scAAV2/9 vector to contain a replacement 'codon-modified' rhodopsin transgene (RhoR2) that was resistant to degradation by the microRNA. We found that delivery of the RhoR2 by scAAV2/9 is capable of restoring vision to rhodopsin knockout mice, and rescuing our novel transgenic huRhoP347S mouse model of dominant RP. Average a-wave responses of RhoR2-injected eyes were 1.8-fold higher than those of control-injected eyes. We found that delivery of the microRNA and replacement rhodopsin in a 1:2 ratio produced an average electroretinography (ERG) a-wave response of 17.4±2.9 compared to 6.5±2.8 μV for eyes injected with negative control virus.

Publication types

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

MeSH terms

  • Animals
  • Dependovirus / genetics
  • Disease Models, Animal*
  • Gene Silencing
  • Genetic Therapy*
  • Mice / genetics*
  • MicroRNAs / metabolism
  • Mutation, Missense
  • Photoreceptor Cells, Vertebrate / metabolism
  • Retinitis Pigmentosa / genetics
  • Retinitis Pigmentosa / pathology
  • Retinitis Pigmentosa / therapy*
  • Rhodopsin / genetics
  • Rhodopsin / metabolism
  • Transgenes

Substances

  • MicroRNAs
  • Rhodopsin