Apolipoprotein A-V associates with intrahepatic lipid droplets and influences triglyceride accumulation

Apolipoprotein A-V (apoA-V), secreted solely by the liver, is a low abundance protein that strongly influences plasma triglyceride (TG) levels. In vitro, in transfected hepatoma cell lines apoA-V is largely retained within the cell in association with cytosolic lipid droplets (LD). To evaluate if this is true in vivo, in the present study the amount of apoA-V in the plasma compartment versus liver tissue was determined in APOAS transgenic (Tg) mice. The majority of total apoA-V (similar to 80%) was in the plasma compartment. Injection of AP0A5 Tg mice with heparin increased plasma apoA-V protein levels by similar to 25% indicating the existence of a heparin-releasable pool. Intrahepatic apoA-V was associated with LD isolated from livers of wild type (WT) and AP0A5 Tg mice. Furthermore, livers from AP0A5 Tg mice contained significantly higher amounts of TG than livers from WT or apoa5 knockout mice suggesting that apoA-V influences intrahepatic TG levels. (C) 2010 Elsevier B.V. All rights reserved.