INIBIOLP   05426
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE LA PLATA "PROF. DR. RODOLFO R. BRENNER"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Effect of membrane composition on cholesterol efflux mediated by human apolipoprotein A-I
Autor/es:
S. JAUREGUIBERRY; A. TRICERRI; RIMOLDI OJ
Lugar:
Rosario, Argentina
Reunión:
Congreso; XLII Reunión Anual de SAIB; 2006
Institución organizadora:
Sociedad Argentina de Investigaciones Bioquímicas y Biología Molecular
Resumen:
Cholesterol efflux mediated by apoA-I involves different pathways, including active efflux via the ABCA1 transporter, and passive pathways mediated by scavenger receptor BI. To evaluate the importance of membrane composition and lateral domain phase separation on apoA-I interactions and cholesterol mobilization, we constructed a permanent Chinese Hamster Ovary Cell line (CHO-K1) overexpressing the rat Stearoyl CoA Desaturase gen (SCD). Cells transfected with an expression vector in mammalian hosts (containing or not the gen for the SCD) induced a stable increase in fatty acid unsaturation at membrane phospholipids. SCD mRNA overexpression was characterized by northern blotting. SCD activity was evaluated by analysis of fatty acid composition at the plasma membrane, showing a relative increase of 2.1 times in the ratio 16:1/16:0 and 18:1/18:0. In addition, we proved that, as expected, expression level of ABCA1 was not modified in SCD-overexpressing cells, by western blotting. Incubation of SCD overexpressing cells with ApoA-1, resulted in a decresed cholesterol removal, as well as in the formation of lipid-apoliprotein particles. Furthermore, membrane fluidity was assesed by Laurdan General Polarization (GP) and 2-photon fluorescence microscopy, in control cells and in cells treated with methyl beta ciclo dextrines. Results are discussed in terms of lateral phase separation.