Opposite effect of caveolin-1 in the metabolism of high-density and low-density lipoproteins
| Autor: | Louise Brissette, To Quyen Truong, Philippe Bourgeois, Dominique Aubin, Louise Falstrault |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
Caveolin 1
Cell High density Transfection Cell Line Cell Line Tumor Caveolae Parenchyma Low density medicine Humans RNA Messenger Receptor Molecular Biology Reverse Transcriptase Polymerase Chain Reaction Chemistry Liver Neoplasms Biological Transport Serum Albumin Bovine Cell Biology Metabolism Recombinant Proteins Cell biology Lipoproteins LDL Kinetics medicine.anatomical_structure Liver Biochemistry Lipoproteins HDL |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids. 1761:24-36 |
| ISSN: | 1388-1981 |
| DOI: | 10.1016/j.bbalip.2005.12.004 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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