title: Protection of cone photoreceptor M-opsin degradation with 9-cis-β-carotene-rich alga Dunaliella bardawil in Rpe65(-/-) mouse retinal explant culture.
abstract: OBJECTIVE
  RPE65, a retinal pigment epithelium-specific 65-kDa protein, plays a critical role in the visual cycle of the eye. Rpe65(-/-) mice develop vision loss due to a lack of 11-cis-retinal, degradation of M-opsin and mislocalization of S-opsin. Several studies have suggested that 9-cis-β-carotene, a precursor of 9-cis-retinal and all-trans-retinal, could have therapeutic applications in vision loss. We therefore examined whether Dunaliella bardawil, a 9-cis-β-carotene-rich alga, protects against the degradation of M-opsin using Rpe65(-/-) mouse retinal explant cultures.
  
  
  METHODS
  The eyes of three-week-old Rpe65(-/-) and C57BL/6 J mice were enucleated, and the corneas were removed. The eyecups were incubated with culture medium in the absence or presence of D. bardawil for 6 h to 4 days. Localizations of M-opsin proteins in the retina were observed immunohistochemically. Expression levels of M-opsin, S-opsin and rhodopsin proteins were evaluated by Western blot analysis.
  
  
  RESULTS
  In C57BL/6 J mouse retina, no change was observed in localization and expression levels of M-opsin in the explant culture system. In Rpe65(-/-) mouse retina, the amount of M-opsin protein was decreased in the photoreceptor outer segment after 6 h to 4 days of culture. However, the presence of D. bardawil significantly ameliorated this decrease. In contrast, expression levels of S-opsin and rhodopsin were unchanged in the presence of the explant culture.
  
  
  CONCLUSIONS
  These results demonstrate that D. bardawil treatment protects against M-opsin degradation in Rpe65(-/-) mouse retina and suggest that D. bardawil has therapeutic potential for retinal degeneration caused by Rpe65 gene mutation, such as Leber congenital amaurosis and retinitis pigmentosa.
authors.affiliation: Department of Ophthalmology, Hirosaki University Graduate School of Medicine , Hirosaki , Japan and.
authors.forename: Taku
authors.initials: T
authors.lastname: Ozaki
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Nakazawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Kudo
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hirano
authors.forename: Kaori
authors.initials: K
authors.lastname: Suzuki
authors.forename: Sei-ichi
authors.initials: S
authors.lastname: Ishiguro
mesh_terms: D000818:Animals; D015153:Blotting, Western; D000460:Chlorophyta / Q000737:chemistry*; D055358:Cone Opsins / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009924:Organ Culture Techniques; D010936:Plant Extracts / Q000494:pharmacology*; D012160:Retina / Q000378:metabolism*; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism; D012162:Retinal Degeneration / Q000378:metabolism / Q000517:prevention & control*; D012243:Rhodopsin / Q000378:metabolism; D017299:Rod Opsins / Q000378:metabolism*; D019207:beta Carotene / Q000737:chemistry*; D019745:cis-trans-Isomerases / Q000502:physiology*; D000099178:Retinoid Isomerohydrolase
chemical_list: D055358:Cone Opsins; D010936:Plant Extracts; D012243:Rhodopsin; D017299:Rod Opsins; D019207:beta Carotene; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase; C095854:middle-wavelength opsin
keywords: 9-Cis-β-carotene; Dunaliella bardawil; Leber congenital amaurosis; M-opsin; RPE65; cone photoreceptor; retinitis pigmentosa