title: Noninvasive two-photon imaging reveals retinyl ester storage structures in the eye.
abstract: Visual sensation in vertebrates is triggered when light strikes retinal photoreceptor cells causing photoisomerization of the rhodopsin chromophore 11-cis-retinal to all-trans-retinal. The regeneration of preillumination conditions of the photoreceptor cells requires formation of 11-cis-retinal in the adjacent retinal pigment epithelium (RPE). Using the intrinsic fluorescence of all-trans-retinyl esters, noninvasive two-photon microscopy revealed previously uncharacterized structures (6.9 +/- 1.1 microm in length and 0.8 +/- 0.2 microm in diameter) distinct from other cellular organelles, termed the retinyl ester storage particles (RESTs), or retinosomes. These structures form autonomous all-trans-retinyl ester-rich intracellular compartments distinct from other organelles and colocalize with adipose differentiation-related protein. As demonstrated by in vivo experiments using wild-type mice, the RESTs participate in 11-cis-retinal formation. RESTs accumulate in Rpe65-/- mice incapable of carrying out the enzymatic isomerization, and correspondingly, are absent in the eyes of Lrat-/- mice deficient in retinyl ester synthesis. These results indicate that RESTs located close to the RPE plasma membrane are essential components in 11-cis-retinal production.
authors.affiliation: Department of Ophthalmology, University of Washington, 1959 NE Pacific St., Box 356485, Seattle, WA 98195-6485, USA.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Imanishi
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Batten
authors.forename: David W
authors.initials: DW
authors.lastname: Piston
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Baehr
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Palczewski
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins; D022162:Cytoplasmic Vesicles / Q000737:chemistry* / Q000378:metabolism; D004224:Diterpenes; D004952:Esters / Q000032:analysis*; D005123:Eye / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D005136:Eye Proteins; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence / Q000379:methods; D008958:Models, Molecular; D015394:Molecular Structure; D000070780:Perilipin-2; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000378:metabolism*; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D012172:Retinaldehyde / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism*; D014796:Visual Perception / Q000502:physiology*; D014801:Vitamin A / Q000737:chemistry* / Q000378:metabolism; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase
chemical_list: D000217:Acyltransferases; D002352:Carrier Proteins; D004224:Diterpenes; D004952:Esters; D005136:Eye Proteins; D008565:Membrane Proteins; D000070780:Perilipin-2; D011506:Proteins; D012172:Retinaldehyde; D014801:Vitamin A; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase; C000602983:Plin2 protein, mouse; C031390:9-cis-retinal; C056942:lecithin-retinol acyltransferase