Document Detail

Cell-surface binding sites for high density lipoproteins do not mediate efflux of cholesterol from human fibroblasts in tissue culture.
MedLine Citation:
PMID:  2846734     Owner:  NLM     Status:  MEDLINE    
The present investigation was designed to test the hypothesis that binding sites for high density lipoproteins (HDL3) on cell surfaces of peripheral tissues mediate cholesterol efflux from these cells. This hypothesis had been formulated to explain two observations: 1) HDL3 binding to peripheral cells and HDL3-mediated cholesterol efflux from these cells had both been found to saturate at similar unbound (free) HDL3 concentrations; and 2) both of these processes had been found to be similarly "up-regulated" by loading the cells with cholesterol. In the present study, however, we found that the "specific" binding of HDL3 to cholesterol-loaded human fibroblasts was saturated at a free HDL3 concentration of approximately 20 micrograms protein/ml, whereas efflux of cholesterol from these cells to HDL3 did not "saturate" even at a free HDL3 concentration of 2000 micrograms protein/ml. In addition, we found that the increase in cholesterol efflux caused by loading the fibroblasts with cholesterol was no greater when the acceptor particles were HDL3 than when albumin or phospholipid vesicles served as acceptors, despite a marked increase in HDL3 binding to these cells. Because HDL3 binding to these cells and HDL3-mediated cholesterol efflux from these cells do not saturate at similar free HDL3 concentrations, and because the cholesterol-induced increase in HDL3 binding is not accompanied by a similar increase in cholesterol efflux that is specific for HDL3, we conclude that the described HDL3 binding sites on human fibroblasts do not mediate cholesterol efflux.
C M Mendel; S T Kunitake
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of lipid research     Volume:  29     ISSN:  0022-2275     ISO Abbreviation:  J. Lipid Res.     Publication Date:  1988 Sep 
Date Detail:
Created Date:  1988-12-20     Completed Date:  1988-12-20     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0376606     Medline TA:  J Lipid Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1171-8     Citation Subset:  IM    
Cardiovascular Research Institute, University of California, San Francisco 94143-0130.
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MeSH Terms
Carrier Proteins*
Cells, Cultured
Cholesterol / metabolism*
Fibroblasts / metabolism
Lipoproteins, HDL*
Microscopy, Electron
RNA-Binding Proteins*
Receptors, Cell Surface / physiology*
Receptors, Lipoprotein*
Grant Support
Reg. No./Substance:
0/Carrier Proteins; 0/Lipoproteins, HDL; 0/RNA-Binding Proteins; 0/Receptors, Cell Surface; 0/Receptors, Lipoprotein; 0/high density lipoprotein receptors; 147605-06-9/high density lipoprotein binding protein; 57-88-5/Cholesterol

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