Interaction of discoidal APOAI lipoprotein complexes with CHO KI cells. Influence of disc size and cholesterol

GONZALEZ, M. C.; TOLEDO, J. D.; TRICERRI, A. Y GARDA, H.

Pinamar, Argentina

Congreso; 41 Congreso Nacional de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB) y 10th Congresss of Panamerican Association for Biochemistry and Molecular Biology (PABMB); 2005

PABMB, SAIB y SAN

  Apolipoprotein AI (apoAI) adopts different conformations in discoidal high density lipoprotein (HDL), depending on disc size and cholesterol (Ch) content. These alternative conformations, in special those of a central domain, seem to be quite important for determining the membrane affinity and Ch exchange rate between discs and lipid bilayers. This central domain is also responsible for triggering the mobilization of intracellular Ch pools toward the cell membrane (Gonzalez et al, SAIB 2004). Thus, its alternative conformations could modulate these cellular responses. In order to test this possibility, we have reconstituted different sized apoAI discoidal complexes (rHDL) containing 1-palmitoyl-2-oleyl-phosphatidylcholine (POPC) or POPC and Ch, and compared their activity in promoting cellular Ch efflux and mobilization of de novo synthesized Ch toward the cell membrane. Although apoAI lipidation decreases its capacity to promote Ch efflux, this effect is independent of disc size and composition. On the contrary, mobilization of de novo synthesized Ch is strongly influenced by these factors, being the biggest Ch-containing particles entirely inactive to trigger this process.