Gene Therapy Fully Restores Vision to the All-Cone Nrl(-/-) Gucy2e(-/-) Mouse Model of Leber Congenital Amaurosis-1

Hum Gene Ther. 2015 Sep;26(9):575-92. doi: 10.1089/hum.2015.053. Epub 2015 Aug 6.

Abstract

Mutations in GUCY2D are the cause of Leber congenital amaurosis type 1 (LCA1). GUCY2D encodes retinal guanylate cyclase-1 (retGC1), a protein expressed exclusively in outer segments of photoreceptors and essential for timely recovery from photoexcitation. Recent clinical data show that, despite a high degree of visual disturbance stemming from a loss of cone function, LCA1 patients retain normal photoreceptor architecture, except for foveal cone outer segment abnormalities and, in some patients, foveal cone loss. These results point to the cone-rich central retina as a target for GUCY2D replacement. LCA1 gene replacement studies thus far have been conducted in rod-dominant models (mouse) or with vectors and organisms lacking clinical translatability. Here we investigate gene replacement in the Nrl(-/-) Gucy2e(-/-) mouse, an all-cone model deficient in retGC1. We show that AAV-retGC1 treatment fully restores cone function, cone-mediated visual behavior, and guanylate cyclase activity, and preserves cones in treated Nrl(-/-) Gucy2e(-/-) mice over the long-term. A novel finding was that retinal function could be restored to levels above that in Nrl(-/-) controls, contrasting results in other models of retGC1 deficiency. We attribute this to increased cyclase activity in treated Nrl(-/-) Gucy2e(-/-) mice relative to Nrl(-/-) controls. Thus, Nrl(-/-) Gucy2e(-/-) mice possess an expanded dynamic range in ERG response to gene replacement relative to other models. Lastly, we show that a candidate clinical vector, AAV5-GRK1-GUCY2D, when delivered to adult Nrl(-/-) Gucy2e(-/-) mice, restores retinal function that persists for at least 6 months. Our results provide strong support for clinical application of a gene therapy targeted to the cone-rich, central retina of LCA1 patients.

Publication types

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

MeSH terms

  • Animals
  • Basic-Leucine Zipper Transcription Factors / genetics*
  • Dependovirus / genetics
  • Disease Models, Animal
  • Eye Proteins / genetics*
  • Genetic Therapy
  • Genetic Vectors
  • Guanylate Cyclase / genetics*
  • Guanylate Cyclase / metabolism
  • Injections, Intraocular
  • Leber Congenital Amaurosis / genetics
  • Leber Congenital Amaurosis / pathology
  • Leber Congenital Amaurosis / therapy*
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Opsins / genetics
  • Opsins / metabolism
  • Receptors, Cell Surface / genetics*
  • Receptors, Cell Surface / metabolism
  • Retinal Cone Photoreceptor Cells / pathology
  • Treatment Outcome
  • Vision, Ocular

Substances

  • Basic-Leucine Zipper Transcription Factors
  • Eye Proteins
  • Nrl protein, mouse
  • Opsins
  • Receptors, Cell Surface
  • Guanylate Cyclase
  • Gucy2d protein, mouse
  • Gucy2e protein, mouse

Supplementary concepts

  • Amaurosis congenita of Leber, type 1