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Preferential uptake of xanthophylls by human retinal pigment epithelial cells is mediated by scavenger receptor B1
Author(s) -
Harrison Earl Howard,
During Alexandrine
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.313.5
Subject(s) - xanthophyll , zeaxanthin , cd36 , lutein , chemistry , retinal , retinal pigment epithelium , transfection , biochemistry , microbiology and biotechnology , receptor , carotenoid , biology , gene
The purpose of this study was to investigate mechanisms by which carotenoids are taken up by human retinal pigment epithelial cells (ARPE‐19). When ARPE‐19 cells were fully differentiated (7–9 weeks), the xanthophylls lutein (LUT) and zeaxanthin (ZEA) were taken up by cells to an extent about two‐fold higher than beta‐carotene (b‐C) (P < 0.05). At 9 weeks of differentiation, the extents of uptake were 1.6% for b‐C, 2.5% for LUT and 3.2% for ZEA under identical incubation conditions. Differentiated ARPE‐19 cells did not exhibit any detectable beta‐carotene oxygenase 1 enzyme activity or convert exogenous b‐C into vitamin A. In experiments using specific antibodies against the lipid transporters CD36 and SR‐B1 cellular uptake of b‐C and ZEA were significantly decreased (40–60%) by treatment with anti‐SR‐B1, but not with anti‐CD36. Transfection of siRNA for SR‐B1 led to marked inhibition of SR‐B1 protein expression (∼90% knock‐down), which resulted in a decrease of cellular uptake of b‐C and ZEA by 51% and 87%, respectively. Thus, RPE cells preferentially take up xanthophylls versus the carotene b‐C by a process that appears to be entirely SR‐B1‐dependent for zeaxanthin and partly so for beta‐carotene. This mechanism may explain, in part, the preferential accumulation of xanthophylls in the macula of the retina. Supported by NIH Grant R01 HL049879.