Mislocalization and degradation of human P23H-rhodopsin-GFP in a knockin mouse model of retinitis pigmentosa

Invest Ophthalmol Vis Sci. 2011 Dec 28;52(13):9728-36. doi: 10.1167/iovs.11-8654.


Purpose: To engineer a knockin mouse model that can be used to monitor the effects of treatments on degradation and mislocalization of proline-to-histidine change at codon 23 (P23H) rhodopsin, a common cause of autosomal dominant retinitis pigmentosa (ADRP). The goal was to introduce a gene that expressed rhodopsin at low levels to avoid rapid retinal degeneration, and with a readily visible tag to make it easy to distinguish from wild type rhodopsin.

Methods: One copy of the endogenous mouse rhodopsin gene was replaced with a mutant human rhodopsin gene that encodes P23H-rhodopsin fused to enhanced green fluorescent protein (GFP) at its C terminus. The gene includes a LoxP site in the sequence corresponding to the 5'-untranslated region, which greatly reduces translation efficiency. Characterized are the resulting heterozygous and homozygous P23H-hRho-GFP mouse lines for mRNA and protein expression, P23H-rhodopsin localization in rod cells, effects on visual function, and retinal degeneration.

Results: The retinas of heterozygous P23H-hRho-GFP mice are morphologically and functionally very similar to those of wild type mice, and they display little cell death over time. P23H-hRho-GFP mice transcribe the knockin gene as efficiently as the endogenous mouse allele, but they contain much less of the protein product than do knockin mice expressing nonmutant hRho-GFP, indicating that substantial degradation of P23H-rRho-GFP occurs in mouse rod cells. The remaining P23H-hRho-GFP mislocalizes to the inner segment and outer nuclear layer, with only approximately 20% in rod outer segments.

Conclusions: P23H-hRho-GFP mice provide a valuable tool for evaluating the efficacy of potential therapies for ADRP that influence the levels or localization of P23H-rhodopsin.

Publication types

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

MeSH terms

  • Animals
  • Blotting, Northern
  • Codon
  • Disease Models, Animal*
  • Electroretinography
  • Gene Expression Regulation / physiology
  • Gene Knock-In Techniques
  • Genotyping Techniques
  • Green Fluorescent Proteins / genetics*
  • Histidine / genetics
  • Mice
  • Mice, Inbred C57BL
  • Microscopy, Confocal
  • Mutagenesis, Site-Directed
  • Mutation
  • Proline / genetics
  • Recombinant Fusion Proteins / genetics*
  • Retinal Photoreceptor Cell Inner Segment / metabolism
  • Retinal Photoreceptor Cell Outer Segment / metabolism
  • Retinitis Pigmentosa / genetics*
  • Retinitis Pigmentosa / metabolism
  • Retinitis Pigmentosa / pathology
  • Rhodopsin / genetics*


  • Codon
  • Recombinant Fusion Proteins
  • enhanced green fluorescent protein
  • Green Fluorescent Proteins
  • Histidine
  • Rhodopsin
  • Proline