Deficiency of acyl CoA cholesterol acyl transferase activity in suncus liver.

We reported previously that apolipoprotein B is not actively secreted from suncus liver. In the present study we have investigated the hepatic cholesterol metabolism, which plays a critical role in the secretion of apo B. We found that the activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase in suncus liver is high and that acyl-coenzyme A: cholesterol acyltransferase (ACAT) activity is almost absent in contrast to rats. As a result, the hepatic content of cholesterol ester, upon which apoprotein B secretion partly depends, is very low in suncus. The deficiency of ACAT activity may cause the defect in active secretion of apoprotein B-containing lipoproteins in suncus.