September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Substitution of Rod for Cone Opsin Increases the Resistance of M-Cones to Chromophore Deficiency-Induced Degeneration
Author Affiliations & Notes
  • Alexander V Kolesnikov
    Ophthalmology and Visual Sciences, Washington University in Saint Louis, Saint Louis, Missouri, United States
  • Chloe Potter
    Ophthalmology and Visual Sciences, Washington University in Saint Louis, Saint Louis, Missouri, United States
  • David Razafsky
    Ophthalmology and Visual Sciences, Washington University in Saint Louis, Saint Louis, Missouri, United States
  • Andrew Hughes
    Pathology and Immunology, Washington University in Saint Louis, Saint Louis, Missouri, United States
  • Joseph C Corbo
    Pathology and Immunology, Washington University in Saint Louis, Saint Louis, Missouri, United States
  • Didier Hodzic
    Ophthalmology and Visual Sciences, Washington University in Saint Louis, Saint Louis, Missouri, United States
  • Vladimir J Kefalov
    Ophthalmology and Visual Sciences, Washington University in Saint Louis, Saint Louis, Missouri, United States
  • Footnotes
    Commercial Relationships   Alexander Kolesnikov, None; Chloe Potter, None; David Razafsky, None; Andrew Hughes, None; Joseph Corbo, None; Didier Hodzic, None; Vladimir Kefalov, None
  • Footnotes
    Support  NIH Grants EY019312 and EY021126 (VJK), EY022632 (DH), EY024958 and EY025196 (JCC), RPB (VJK and JCC).
Investigative Ophthalmology & Visual Science September 2016, Vol.57, No Pagination Specified. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to Subscribers Only
      Sign In or Create an Account ×
    • Get Citation

      Alexander V Kolesnikov, Chloe Potter, David Razafsky, Andrew Hughes, Joseph C Corbo, Didier Hodzic, Vladimir J Kefalov; Substitution of Rod for Cone Opsin Increases the Resistance of M-Cones to Chromophore Deficiency-Induced Degeneration. Invest. Ophthalmol. Vis. Sci. 201657(12):.

      Download citation file:


      © 2017 Association for Research in Vision and Ophthalmology.

      ×
  • Supplements
Abstract

Purpose : Leber Congenital Amaurosis (LCA) is a severe retinal dystrophy causing child blindness. Mutations in retinoid isomerase RPE65 account for up to 16% of LCA cases and lead to early loss of cones. The mechanisms of this disease are poorly understood. Cone pigments are generally less stable and rely on the supply of visual chromophore. We tested the hypothesis that the low stability of cone opsin makes mammalian cones susceptible to degeneration under conditions of sustained chromophore deprivation in the absence of RPE65.

Methods : We generated a novel knockin mouse model expressing rod pigment in cones instead of their native M-opsin (RhoKI). Cone expression of rhodopsin was confirmed in RhoKI-Rho-/- animals by IHC and further quantified by qPCR. To induce chromophore deficiency, we generated RhoKI-Rpe65-/-Gnat1-/- mice and their Rpe65-/-Gnat1-/- controls lacking rod signaling. We then compared their cone numbers and M-cone transretinal ERG responses (with exogenously added 9-cis-retinal) at the ages of 1 or 5 months.

Results : The total level of rhodopsin mRNA in RhoKI-Rho-/- retinas was 15-fold lower than that of native M-cone pigment in control (Rho-/-) mice. This caused corresponding desensitization of M-cones in RhoKI animals. However, their maximal cone response amplitude and their amount of cone transducin were normal. Rpe65-/-Gnat1-/- mice had rapidly progressing degeneration of nearly all ventral and most dorsal cones. Notably, there was a substantial preservation of central-dorsal cones in 5-month-old RhoKI-Rpe65-/-Gnat1-/- animals. Furthermore, RPE65-deficient cones expressing rhodopsin had a 2-fold higher maximal response and 10-fold higher sensitivity than age-matched controls. Following a chromophore treatment, the overall physiological function of RhoKI-Rpe65-/-Gnat1-/- cones was only 2–2.5-fold lower than in RhoKI-Gnat1-/- animals with normal chromophore supply. This is in stark contrast to Rpe65-/-Gnat1-/- cones whose sensitivity was several orders of magnitude lower than that in Gnat1-/- mice.

Conclusions : Cones expressing rhodopsin are viable and have robust phototransduction. The substitution of cone M-opsin with even small amount of more stable rhodopsin increases the survival of cones under conditions of severe chromophore deficiency. This opens the potential for respective gene-therapy based approach for treating LCA and related retinal pathologies.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×