Document Detail


Opposite effect of caveolin-1 in the metabolism of high-density and low-density lipoproteins.
MedLine Citation:
PMID:  16443388     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Receptors of the scavenger class B family were reported to be localized in caveolae, the cell surface microdomains rich in free cholesterol and glycosphyngolipids, which are characterized by the presence of caveolin-1. Parenchymal hepatic and hepatoma HepG2 cells express very low levels of caveolin-1. In the present study, stable transformants of HepG2 cells expressing caveolin-1 were generated to address the effect of caveolin-1 on receptor activity. Compared to normal cells, these cells show higher (125)I-bovine serum albumin (BSA) uptake and cholesterol efflux, two indicators of functional caveolae. By immunoprecipitation, cell fractionation and confocal analyses, we found that caveolin-1 is well colocalized with the cluster of differentiation-36 (CD36) and the low-density lipoprotein (LDL) receptor (LDLr) but to a lesser extent with the scavenger receptor class B type I (SR-BI) in HepG2 cells expressing caveolin-1. However, caveolin-1 expression favors the dimerization of SR-BI. Two clones of cells expressing caveolin-1 were investigated for their lipoprotein metabolism activity. Compared to normal cells, these cells show a 71-144% increase in (125)I-LDL degradation. The analysis of the cholesteryl esters (CE)-selective uptake (CE association minus protein association) revealed that the expression of caveolin-1 in HepG2 cells decreases by 59%-73% LDL-CE selective uptake and increases high-density lipoprotein (HDL)-CE selective uptake by 44%-66%. We conclude that the expression of caveolin-1 in HepG2 cells moves the balance of LDL degradation/CE selective uptake towards degradation and favors HDL-CE selective uptake. Thus, in the normal hepatic parenchymal situation where caveolin-1 is poorly expressed, LDL-CE selective uptake is the preferred pathway.
Authors:
To Quyen Truong; Dominique Aubin; Philippe Bourgeois; Louise Falstrault; Louise Brissette
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-01-18
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  1761     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  2006 Jan 
Date Detail:
Created Date:  2006-03-13     Completed Date:  2006-05-16     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  24-36     Citation Subset:  IM    
Affiliation:
Département des Sciences Biologiques, Université du Québec à Montréal, C.P. 8888, Succursale Centre-ville, Montréal, Québec, Canada H3C 3P8. truong.to_quyen@courrier.uqam.ca
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MeSH Terms
Descriptor/Qualifier:
Biological Transport
Caveolin 1 / genetics,  physiology*
Cell Line
Cell Line, Tumor
Humans
Kinetics
Lipoproteins, HDL / metabolism*
Lipoproteins, LDL / metabolism*
Liver
Liver Neoplasms
RNA, Messenger / genetics
Recombinant Proteins / pharmacology
Reverse Transcriptase Polymerase Chain Reaction
Serum Albumin, Bovine / metabolism
Transfection
Chemical
Reg. No./Substance:
0/Caveolin 1; 0/Lipoproteins, HDL; 0/Lipoproteins, LDL; 0/RNA, Messenger; 0/Recombinant Proteins; 0/Serum Albumin, Bovine

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