Efect of apoA-I lipidation state on colesterol and phospholipids mobilization and efflux from cells.

GONZALEZ, M. C.; CABALEIRO, L. V.; TOLEDO, J. D.; GARDA, H. A.

Carlos Paz, Córdoba, Rca. Argentina.

Congreso; 44th Reunión anual. Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2008

Sociedad Argentina de Bioquímica y Biología Molecular.

Apolipoprotein AI (apoAI) conformational flexibility permit to adopt different conformations in discoidal high density lipoprotein (HDL), depending on cholesterol (Co) content and discs size.These alternative conformations, specially those concerning to central domain, seem to be important factors determining the membrane affinity and the Co exchange between discs and lipid bilayers.In order to know if alternative protein conformations result in different cellular responses, we have prepared reconstituted high density lipoproteins (rHDL) of different size and Co-content.They were used to compare cellular Co and phospholipids remotion and mobilization of intracellular Co pools, as the one available to be esterified by acyl CoA cholesterol acyl transferase (ACAT). We have observed that all sized rHDL promote significatively cellular Co removing, when they are tested at 3 and 12 hs of treatment.This ability is independent of Co content. When we studied intracellular movilization of Co pools, we observed that only apoAI, and Co-free rHDL particles of 96Å and 120Å generate Co movilization from ACAT specific pools. Phospholipid remotion was only promoted by apoAI and rHDL without Co of 78 A, after 12 hs incubation.The more Co content in particles the less activity to trigger this process. In CHO cells phospholipid remotion is a late process respect to Co remotion.