July 2018
Volume 59, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2018
A Novel non-Retinoid RPE65 Inhibitor CU239 Prevents Light-Induced Degeneration of the Mouse Retina through Slowing of the Visual Cycle
Author Affiliations & Notes
  • Gennadiy P Moiseyev
    Univ of Oklahoma Hlth Sci Ctr, Edmond, Oklahoma, United States
  • Younghwa Shin
    Univ of Oklahoma Hlth Sci Ctr, Edmond, Oklahoma, United States
  • Yusuke Takahashi
    Univ of Oklahoma Hlth Sci Ctr, Edmond, Oklahoma, United States
  • Konstantin Petrukhin
    Columbia University, New York, New York, United States
  • Jian-Xing (Jay) Ma
    Univ of Oklahoma Hlth Sci Ctr, Edmond, Oklahoma, United States
  • Footnotes
    Commercial Relationships   Gennadiy Moiseyev, None; Younghwa Shin, None; Yusuke Takahashi, None; Konstantin Petrukhin, None; Jian-Xing (Jay) Ma, None
  • Footnotes
    Support  NIH grants EY018659, EY012231, EY019309, GM104934, GM122744, a Juvenile Diabetes Research Foundation (JDRF) grant (2-SRA-2014-147-Q-R),an Oklahoma Center for the Advancement of Science and Technology (OCAST) grant (HR16-041) and Presbyterian Health Foundation bridge grant.
Investigative Ophthalmology & Visual Science July 2018, Vol.59, 5330. doi:
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      Gennadiy P Moiseyev, Younghwa Shin, Yusuke Takahashi, Konstantin Petrukhin, Jian-Xing (Jay) Ma; A Novel non-Retinoid RPE65 Inhibitor CU239 Prevents Light-Induced Degeneration of the Mouse Retina through Slowing of the Visual Cycle. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5330.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : : Slowing the visual cycle by inhibition of the rate-limiting step catalyzed by RPE65 is a promising strategy to decrease the accumulation of A2E and to prevent retina degeneration. Recently, using in vitro retinol isomerase assay, we have identified CU239 as a novel non-retinoid compound capable of specifically inhibiting RPE65. The aim of this study was to investigate if CU239 inhibits visual cycle in vivo and prevents light induced retina degeneration (LIRD) in a mouse model.

Methods : To determine the inhibition mode of the CU239, an adenoviral expression vector was used to express chicken RPE65 in 293A cells, and then RPE65 was used in a liposome-based isomerohydrolase assay. Fluorescence titration method was used to determine dissociation constant of CU239 and RPE65. BALB/c mice were injected intraperitoneally with CU239 or vehicle 1 h before exposure to white fluorescent light at 8000 lux intensity for 3 h. The retinal damage was assessed 5 days following LIRD using histology and ERG. Retinoid profiles recovery was assayed using HPLC.

Results : CU239 inhibited RPE65 in a competitive manner with Ki=9.9±0.8 μM. CU239 quenched intrinsic tryptophan fluorescence of RPE65 in a concentration dependent manner. The apparent dissociation constant calculated from the titration data equals 230±48 nM. Analysis of retinoid profiles demonstrated that mice injected with 52 mg/kg of CU239 exhibited the most substantial decrease in 11-cis-retinal regeneration after bleach (less than 40% of vehicle control). ERG analysis on the mice injected with CU239 prior to LIRD revealed significantly higher visual sensitivity compared to the vehicle group. The retinas of CU239 injected mice showed milder reduction of ONL thickness as compared to the control.

Conclusions : CU239 potently and selectively inhibited conversion of all-trans-retinyl ester to 11-cis-retinol catalyzed by RPE65. The competitive mode of the CU239 inhibition is in agreement with the data of fluorescent titration suggesting direct binding of this inhibitor to RPE65 active site. Mice injected with CU239 exhibited delayed chromophore regeneration after light bleach, and conferred a partial protection of retina against LIRD. Taken together, these results suggest that CU239 may be used to slow down the visual cycle and to prevent accumulation of A2E in Stargardt’s disease and age-related macular degeneration.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

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