Intraretinal lipid transport is dependent on high densitylipoprotein-like particles and class B scavenger receptors

[摘要] Purpose: In our companion paper we demonstrated that circulatinglipoproteins enter the retina via the retinal pigment epithelium (RPE)and possibly Müller cells. In order to understand how these lipids aretransported within the retina, expression and localization of the mainproteins known to be involved in systemic lipid transport wasdetermined.Methods: Expression of ABCA1, apoA1 (the major HDL protein), SR-BI,SR-BII, CD36, lecithin:cholesterol acyltransferase (LCAT), andcholesteryl ester transfer protein (CETP) was determined by reversetranscriptase polymerase chain reaction (RT-PCR) and immunoblots.Localization was determined by immunohistochemistry using fresh monkeyvibrotome sections and imaged by confocal microscopy.Results: ABCA1 and apoA1 were localized to the ganglion cell layer,retinal pigment epithelium (RPE), and rod photoreceptor inner segments.ApoA1 was also observed associated with rod photoreceptor outersegments, presumably localized to the interphotoreceptor matrix (IPM).The scavenger receptors SR-BI and SR-BII localized mainly to theganglion cell layer and photoreceptor outer segments; in the latter theyappear to be associated with microtubules. LCAT and CETP localizedmainly to the IPM.Conclusions: The presence and specific localization of thesewell-known lipid transport proteins suggest that the retina employs aninternal lipid transport mechanism that involves processing andmaturation of HDL-like particles.

[学科分类] 生物化学/生物物理