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Light-induced oxidation of photoreceptor outer segment phospholipids generates ligands for CD36-mediated phagocytosis by retinal pigment epithelium: a potential mechanism for modulating outer segment phagocytosis under oxidant stress conditions. J Biol Chem 2006 Feb 17;281(7):4222-30

Date

12/16/2005

Pubmed ID

16354659

Pubmed Central ID

PMC3627732

DOI

10.1074/jbc.M509769200

Scopus ID

2-s2.0-33645228802 (requires institutional sign-in at Scopus site)   133 Citations

Abstract

Clearance by the retinal pigment epithelium (RPE) of shed photoreceptor outer segments (OSs), a tissue with one of the highest turnover rates in the body, is critical to the maintenance and normal function of the retina. We hypothesized that there is a potential role for photo-oxidation in OS uptake by RPE via scavenger receptor-mediated recognition of structurally defined lipid peroxidation products. We now demonstrate that specific structurally defined oxidized species derived from arachidonyl, linoleoyl, and docosahexanoyl phosphatidylcholine may serve as endogenous ligands on OSs for uptake by RPE via the scavenger receptor CD36. Mass spectrometry studies of retinal lipids recovered from dark-adapted rats following physiological light exposure demonstrate in vivo formation of specific oxidized phosphatidylcholine molecular species possessing a CD36 recognition motif, an oxidatively truncated sn-2 acyl group with a terminal gamma-hydroxy(or oxo)-alpha,beta-unsaturated carbonyl. Cellular studies using RPE isolated from wild-type versus CD36 null mice suggest that CD36 plays a role in engulfment, but not initial binding, of OSs via these oxidized phospholipids. Parallel increases in OS protein-bound nitrotyrosine, a post-translational modification by nitric oxide (NO)-derived oxidants, were also observed, suggesting a possible role for light-induced generation of NO-derived oxidants in the initiation of OS lipid peroxidation. Collectively, these studies suggest that intense light exposure promotes "oxidative tagging" of photoreceptor outer segments with structurally defined choline glycerophospholipids that may serve as a physiological signal for CD36-mediated phagocytosis under oxidant stress conditions.

Author List

Sun M, Finnemann SC, Febbraio M, Shan L, Annangudi SP, Podrez EA, Hoppe G, Darrow R, Organisciak DT, Salomon RG, Silverstein RL, Hazen SL

Author

Roy L. Silverstein MD Professor in the Medicine department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Animals
CD36 Antigens
Ligands
Light
Male
Nitric Oxide
Oxidation-Reduction
Phagocytosis
Phosphatidylcholines
Pigment Epithelium of Eye
Rats
Rats, Sprague-Dawley
Rod Cell Outer Segment