Document Detail

Xanthophylls are preferentially taken up compared with beta-carotene by retinal cells via a SRBI-dependent mechanism.
MedLine Citation:
PMID:  18424859     Owner:  NLM     Status:  MEDLINE    
The purpose of this study was to investigate the mechanisms by which carotenoids [xanthophylls vs. beta-carotene(beta-C)] are taken up by retinal pigment epithelial (RPE) cells. The human RPE cell line, ARPE-19, was used. 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 2-fold higher than beta-C (P < 0.05). At 9 weeks, cellular uptakes were 1.6, 2.5, and 3.2%, respectively, for beta-C, LUT, and ZEA. Similar extents were observed when carotenoids were delivered in either Tween 40 or "chylomicrons" produced by Caco-2 cells. Differentiated ARPE-19 cells did not exhibit any detectable beta-C 15,15'-oxygenase activity or convert exogenous beta-C into vitamin A. When using specific antibodies against the lipid transporters cluster determinant 36 (CD36) and scavenger receptor class B type I (SR-BI), cellular uptake of beta-C and ZEA were significantly decreased (40-60%) with anti-SR-BI but not with anti-CD36. Small interfering RNA transfection for SR-BI led to marked knockdown of SR-BI protein expression (approximately 90%), which resulted in decreased beta-C and ZEA uptakes by 51% and 87%, respectively. Thus, the present data show that RPE cells preferentially take up xanthophylls versus the carotene by a process that appears to be entirely SR-BI-dependent for ZEA and partly so for beta-C. This mechanism may explain, in part, the preferential accumulation of xanthophylls in the macula of the retina.
Alexandrine During; Sundari Doraiswamy; Earl H Harrison
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2008-04-19
Journal Detail:
Title:  Journal of lipid research     Volume:  49     ISSN:  0022-2275     ISO Abbreviation:  J. Lipid Res.     Publication Date:  2008 Aug 
Date Detail:
Created Date:  2008-07-14     Completed Date:  2008-09-11     Revised Date:  2013-06-05    
Medline Journal Info:
Nlm Unique ID:  0376606     Medline TA:  J Lipid Res     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1715-24     Citation Subset:  IM    
Phytonutrients Laboratory, US Department of Agriculture-Agricultural Research Service, Beltsville Human Nutrition Research Center, Beltsville, MD 20705, USA.
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MeSH Terms
Biological Transport
Cell Differentiation
Cells, Cultured
Lutein / metabolism
Pigment Epithelium of Eye / cytology,  metabolism*
Scavenger Receptors, Class B / immunology,  physiology*
Xanthophylls / metabolism*
beta Carotene / metabolism*
Grant Support
Reg. No./Substance:
0/SCARB1 protein, human; 0/Scavenger Receptors, Class B; 0/Xanthophylls; 127-40-2/Lutein; 144-68-3/zeaxanthin; 7235-40-7/beta Carotene

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