Binding of reconstituted discoidal high density lipoproteins to two different cell lines. Influence of size and cholesterol content

CABALEIRO LV; TOLEDO JD; GARDA HA; GONZALEZ MC

San Miguel de Tucumán

Congreso; 45th Reunión anual. Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2009

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

Discoidal high density lipoproteins (dHDL) of apolipoprotein A-I (apoAI) are very important intermediates in the antiatherogenic reverse cholesterol transport mechanism and the genesis of mature HDL in circulation. We have previously shown with reconstituted dHDL that the conformation of apoAI in these lipoprotein complexes is highly dependent on their size and cholesterol content, and also that the ability to interact and exchange cholesterol with artificial membranes decreases as the size and cholesterol content of dHDL increase. More recent results from our lab showing that cholesterol efflux from CHOK1 cells is also inversely correlated with dHDL size and cholesterol content. We have used here an enzyme-linked immunoassay directly on adsorbed cells (ELISA test) to measure the ability of dHDL for binding to murine RAW 264.7 macrophages and CHOK1 epithelial cells in comparison with lipid-free apoAI. In RAW cells small sized dHDL (78 Å diameter) binds to these cells with the same efficiency as lipid-free apoAI. For cholesterol-free dHDL, binding efficiency is higher for larger complexes (96 and 120 Å). The presence of cholesterol in dHDL has no influence on the binding efficiency of the small 78 Å complexes, but it was decreased in the large complexes. In CHOK1 cells binding efficiency was found to be higher than that in lipid-free apoAI.